Surface energetics of lithographic printing plate and

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Theses and Dissertations

1-1-1983

Surface energetics of lithographic printing plate andprinting inks.Yonezo Kato

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SURFACE ENERGETICS OF LITHOGRAPHIC

PRINTING PLATE AND PRINTING INKS

by

Yonezo Kato

A Thesis

Presented to the Graduate Committee

of Lehigh University

in Candidacy for the Degree of

Master of Science

in

Polymer Science and Engineering /^' 1

Lehigh University

October 1980

ProQuest Number: EP76618

All rights reserved

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CERTIFICATE OF APPROVAL

This thesis is accepted and approved in partial ful-

fillment of the requirements for the degree of Master of

Science.

: J-l /?&> (date)

John W. Vanderhoff Professor in Charge

Jfcmn A. I in A. Manson Chairman of Polymer Program Committee

Leonard At. Wenzel Chairman of Chemical Engineering Department

11

ACKNOWLEDGEMENTS

Thanks are expressed to Professor J. W. Vanderhoff

for his interest and helpful suggestions throughout the

author's graduate studies- Special thanks are accorded to

Professor F. M. Powkes for his helpful discussions regard-

ing this research. Sincere thanks are also extended to

faculties, staffs, and colleagues at Lehigh University who

contributed in many ways to the completion of this work.

Financial support from the National Printing Ink

Research Institute and Oji Paper Company Ltd. is also

gratefully acknowledged. In addition, the author wishes

to express his appreciation to the following companies for

providing materials during the work:

Lehigh Litho Inc.

Meer Corporation x

111

TABLE OF CONTENTS

V

Page

LIST OF TABLES vii

LIST OF FIGURES X

ABSTRACT 1

Chapter

1. INTRODUCTION 4

2. THEORY 6

2-1. Dispersion Force , 6

2-2. Intermolecular Interaction 9

2-3. Acid Base Interaction 11

2-4. Kaelble Theory 13

3. SAMPLE PREPARATION 15

3-1. Samples ♦ . . . . 15

3-1-1. Image Area and Non-Image Area of Lithographic Plates 15

3-1-2. Photo-Oxodized Polystyrene Films . . 15

3-1-3. Dry Offset Ink Films 16

3-1-4. Fountain Solutions . . 16

3-1-5. Surfactant Solutions . 17

3-1-6. Gum Arabic Solutions 17

3-2. Surface Tension of the Solutions . , . . 18

3-3. Interfacial Tension. . . , 20

iv

Page

3-3-1, Method ..,.,,,.,..,..» 20

3-3-2, Density of the Solutions 21

3-3-3. Calibration of the Traube Stalagmometer. , 21

3-3-4, Result 23

4. SAMPLE CHARACTERIZATION 26

4-1, Dispersion Component and Non-Dispersion Component of Solids, , , . , 26

4-1-1. Method 26

4-1-2, Image Area and Non-Image Area of Lithographic Plates. ,,.,,,,, 27

4-1-3, Photo-Oxidized Polystyrene Films , . 30

4-1-4, Dry Offset Ink Film. ,.,,,.,. 31

4-2. Dispersion Component of Liquids 33

4-2-1. Characterization of Paraffin Wax and Polyethylene ..... 33

4-2-2. Dispersion Component of the Fountain Solutions , , . , 34

5. CONTACT ANGLE MEASUREMENT 38

5-1. With Water 41

5-2. With Fountain Solution , 46

5-2-1. In Air ,,..,.,.. 46

5-2-2. In Octane. , . 48

5-2-3. In Fountain Solution ... 54

5-3. With Surfactant Solution .,,.,,,. 61

5-3-1. Cationic Surfactant. ,..,,,,. 61

5-3-2. Nonionic Surfactant. . „ 67

v

Page

V 5-4. With Gum Arabic Solution 69

6. DISCUSSION , 74

6-1. Spreading Coefficient 74

6-1-1. Original Method 74

6-1-2. Kaelble Method 83

6-2. Work of Adhesion . , 89

6-2-1. Initial Inking Process 89

6-2-2. During Printing 93

6-3. Work of Adhesion in Octane or in the Fountain Solutions ..... 95

6-4. Tinting and Scumming 98

7. CONCLUSIONS 103

REFERENCES 108

VI

LIST OF TABLES

Table Title Page

3.1 Surface tension and pH of the diluted fountain solution 18

3.2 Surface tension and pH of cationic surfactant solution (hexadecyltrimethylammonium bromide) . 19

3.3 Surface tension and pH of the nonionic surfactant solution (Triton X-100) 19

3.4 Surface tension and pH of the gum arabic solution 19

3.5 Density of the fountain solutions 21

3.6 Experimental interfacial tension between octane and the fountain solutions ....... 24

4.1 Dispersion component and non-dispersion interaction energy of Image and Non-Image Areas. . . 29

4.2 Surface energetic characterization of photo- oxidized polystyrene films 30

4.3 Surface energetic characterization of dry ink film 33

4.4 Dispersion component and non-dispersion interaction energy of paraffin wax and polyethylene. 34

4.5 YT of tne fountain solutions (Lot NO. 1) from

paraffin wax 35

4.6 YT of tne fountain solutions (Lot NO. 2) from

polyethylene. 35

/ 4.7 Non-dispersion interaction energy, I „ calculated by using average Y^C • • • * 37

5.1 Non-dispersion interaction energy of the photo- oxidized polystyrene films with water measured in octane and octane in water 42

vn

Table Title Page

5.2 Non-dispersion interaction energy of Image and Non-Image Areas in octane and in water. . . 45

5.3 Non-dispersion interaction energy and work of adhesion of Image and Non-Image Areas in octane with the fountain solutions 49

5.4 Non-dispersion interaction energy and work of adhesion of the photo-oxidized polystyrene films in octane with the fountain solutions 50

5.5 Non-dispersion interaction energy and work of adhesion of Image or Non-Image Area in the fountain solutions with octane after one minute immersion 55

5.6.1-3 I_w and WA of the photo-oxidized polystyrene films in the fountain solutions with octane drop after one and five minutes immersion ... 56

6.1 Spreading coefficient S2« .' 77

6.2 Spreading coefficient S, . . . . . 81

6.3 Square root of dispersion component and polar component for Image Area and Non-Image Area ... 84

6.4 Comparison of the non-dispersion interaction energy obtained from experimental results and Kaelble method. (Image Area) 88

6.5 Non-dispersion interaction Energy of Non- Image Area with the fountain solutions obtained from experiment and Kaelble method 88

6.6 Works of adhesion between the solids and the fountain solutions or the solids and ink. ... 91

6.7 Works of adhesion of ink and ink or the fountain solutions 94

6.8 Works of adhesion of the fountain solution and fountain solution or ink 94

Vlll

Table Title Page

6.9 Works of adhesion of solids with octane in the fountain solution media 96

6.10 Works of adhesion of solids with fountain solutions in octane medium. , . . 97

xx

LIST OF FIGURES

Figure Title Page

*2.1 Diagram of two monolayers at liquid-liquid interface in which tension resides 8

3.1 The Traube stalagmometer 22

4.1 Non-dispersion component from contact angle of water on photo-oxidized polystyrene films in air 32

4.2 Dispersion force component of fountain solution from contact angle on Paraffin and Polyethylene 36

5.1 Schematic diagram of contact angle measurement in both water and octane phases 39

5.2 Non-dispersion interaction-from contact angle of water on solids in octane and of octane in water s . 43

5.3 Contact angle of fountain solution on solids in air 47

5.4 Contact angle of fountain solution on solids in octane 51

5.5 Work of adhesion and non-dispersion interaction energy of fountain solution on solids in octane 53

5.6 Contact angle! of octane on solids in fountain solution after 1 minute immersion 59

5.7 Contact angle of octane on solids in fountain solution after 5 minutes immersion 60

5.8 Work of adhesion and non-dispersion interaction energy of octane on solids in fountain solution 62

5.9 Contact angle of cationic surfactant solution on solids in air 63

x

Figure Title Page

5.10 Contact angle of cationic surfactant solution (Hexadecyltrimethylammonium bromide) on solids in octane 65

5.11 Contact angle of octane on solids in cationic surfactant solution (Hexadecyltrimethyl- ammonium bromide) 66

5.12 Contact angle of nonionic surfactant solution (Triton X-100) on solids in octane .... 68

5.13 Contact angle of octane in nonionic surfactant solution (Triton X-100) ..... 70

5.14 Contact angle of gum arabic solution on solids in octane 72

5.15 Contact angle of octane on solids in gum arabic solution after 1 and 5 minutes immersion , 73

6.1 Spreading coefficient S~ as a function of surface tension of fountain solution ....... 78

6.2 Spreading coefficient S-i as a function of surface tension of fountain solution . t 82

6.3 Griffith's surface energy for fracture, and graphical determination of the tolerance range for the surface properties of the fountain solution (Kaelble method) 86

XI

ABSTRACT

The surface energetic interaction of lithographic

printing plates, printing inks, and fountain solutions were

defined to determine the mechanism of lithographic printing.

Kodak Polymatic Plates were exposed and prepared as

directed to give a practical hydrophobic image area and a

hydrophilic non-image area. To cover the range between the

low-surface energy image area and the high-surface energy

s£ non-image area, polystyrene films were photooxidized to

varying degrees by exposure to ultraviolet light. A typi-

cal lithographic printing ink was used as the practical

component and n-octane as a model component. A typical

aqueous-based fountain solution was used as the practical

component, and pure water, water-surfactant, and water-gum

arabic mixtures as the model components.

The surface energy of a substrate can be divided into

dispersion and non-dispersion components. The dispersion

component was determined by measuring the contact angle of

methylene iodide or a-bromonaphthalene on the substrate.

However, the non-dispersion interaction energy was deter-

mined instead of non-dispersion component by measuring the

contact angle of water.

Contact angles of fountain solutions on solids in air

or in octane were measured. Similarly, the contact angle

-1-

of octane on solids in fountain solutions were measured.

Then, the following results were found:

1. Cationic surfactants cannot be used as one of

the ingredients of a fountain solution since

the adsorption of a cationic surfactant on

surfaces makes them hydrophobic.

2. Nonionic surfactants can be used. However,

the surface tension of the solution should

not be lower than a critical point (about

32 mN/m) at which emulsification of ink may

be severe and cause tinting.

3. Gum arabic adsorption on non-image areas at

low pH can help repell ink adhesion on non-

image areas. One to two percent glim" arabic

solution may be needed for this purpose.

4. Spreading coefficients S, and S2 of fountain

solution and octane, respectively, never be-

come positive.

5. It is found that non-dispersion interaction

energies are overestimated when using Kaelble

method. These spreading values do not give a

solution for the mechanism of lithographic

printing.

6. After the initial inking process, W (ink-ink)

> Wn (ink-FS) for image areas and W (FS-FS) >

W. (FS-ink) for non-image areas should be

-2-

satisfied provided that non-image areas

are wetted by the fountain solution.

7. The surface tension of fountain solution

should be chosen according to the nature of

image part and non-image part. The more-'''

hydrophobic the image part and the more

hydrophilic the non-image part, the wider

is the latitude for the surface tension of

the fountain solution.

8. The minimum surface tension can be decided

upon consideration of the contact angle of

fountain solutions on the ink film, and

adjusted by nonionic surfactants and iso-

propylalcohol to avoid tinting and scumming.

-3-

1. INTRODUCTION

In the lithographic process, the printing plate com-

prises a hydrophobic image area and a hydrophilic non-image

area; hydrophilic fountain solution is applied to the plate,

followed by hydrophobic ink, so that the non-image area is

covered with a thin film of fountain solution and the image

area, with a thin film of ink; this composite film is trans-

fered to a rubber blanket and then to the paper substrate.

Many studies have been reported on the mechanism of

this printing process, but only a few on its surface

energetics. The mechanism of lithographic printing has

been explained by various ways.

Tollenaar [1] and K. Schlapfer [2] explained it by

wetting phenomena or wettability phenomena such as critical

surface tension.

Padday [3] tried to explain the mechanism by the work

of adhesion and work of cohesion between image area, non-

image area, ink, fountain solution, blanket and paper, and

obtained approximate values of the surface energy of the

image area, non-image area, ink and water.

Badescu [4] calculated the work of mechanical adhesion

and interfacial tension in the presence of water at various

pH values for copper-chromium bimetal plates. He reported

that the work of mechanical adhesion decreased with an

-4-

increase of pH from 5.6 to 7, and offset printing should be

done in neutral media. The printing mechanism is dependent

on the pH value of the fountain solution.

Recently, Kaelble [5] combined surface energetics and

fracture theory and explained the mechanism by the value of

the spreading coefficient. This theory has been accepted

as the first theory which depends upon measurable surface

properties of the ink and dampening solution.

This paper presents the results of a quantitative

surface energetics analysis of lithographic printing

plates, printing inks, and fountain solutions. Tinting

and scumming phenomena are related to the characteristics

of fountain solution, considering the mechanical movement

of the printing press.

-5-

2. THEORY

2-1. Dispersion Force

The intermolecular forces which are the cause of sur-

face tension depend on a variety of well-known intermolecular

forces. Most of these forces, such as the metallic bond or

the hydrogen bond, are a function of specific chemical

nature. On the other hand, London dispersion forces exist

in all types of matter and always give an attractive force

between adjacent atoms or molecules no matter how dissimilar

their chemical natures may be.

The London dispersion forces arise from the inter-

action of fluctuating electronic dipoles with induced di-

poles in neighboring atoms or molecules. These forces

depend on electrical properties of the volume elements in-

volved and the distance between them, and are independent

of temperature. Fowkes [6] proposed that, in a liquid

such as mercury, there are two main interatomic forces—

the metallic bond and the London dispersion forces. Con-

sequently, the surface tension of mercury can be divided

into two parts—the part due to dispersion forces and the

part due to metallic bonds:

d , m /o -i \ VJ = YHg + YHg (2'1)

A similar equation may be written for the surface tension

-6-

of water or any other polar liquid

Y = yd + YP + y

h + Ym + (2.2)

Figure 2.1 [7] shows a model of the interface between

a liquid hydrocarbon and mercury. The interface is com-

posed of the two adjacent interfacial regions, and the

interfacial tensions, therefore, must be the sum of the

tensions in each of these regions. In the interfacial

region of the hydrocarbon, the molecules are attracted to-

ward the bulk hydrocarbon by intermolecular forces which

tend to produce a tension equal to the surface tension of

the hydrocarbon (Y-.) . However, at the interface there is

also an attraction by the London dispersion forces of the

mercury for those hydrocarbon molecules in the interfacial

region. These molecules are in a different force field

than those at the surface of the hydrocarbon because of

this interaction and, therefore, the tension in this layer

is a function of the difference between surface tension

of the hydrocarbon and the attractive force exerted by

the London dispersion force interaction between hydro-

carbon and mercury.

The effect of interfacial attraction on the tension

in the interface can be predicted by the geometric mean of

the dispersion force components of the surface tension of

the hydrocarbon and of the mercury (vy, Y2 ) [8]. Thus,

-7-

Liquid 1

Liquid 2

-> /"~d d

Fig. 2.1. Diagram of two monolayers at liquid-liquid interface in which tension resides. (Fowkes, P.M., "Fundamental Phenomena in the Materials Sciences" vol. 2, 1966)

-8-

the tension in the interfacial region of the hydrocarbon

^ Y-, Y, • Similarly, in the interfacial

region of mercury, the attractive force of bulk mercury is

partially balanced by the attractive force of the hydro-

carbon, and the tension in this layer is equal to

Y2 ~A"i Y? • Since the interfacial tension Y-i 2 ^s tne sum

of the tensions in these two layers:

Y12 = Yl + Y2 " 2^\^2 (2'3)

2-2. Intermolecular Interaction

Since intermolecular attractions result from several

fairly independent phenomena (such as dispersion forces (d),

dipole interactions (p) hydrogen-bond (h), etc.), it is

reasonable to separate out such terms in the work of

adhesion:

W* = W.d + WAP + WA

h + (2.4) A A A A

This principle leads to the widely used equation:

with which interfacial tensions, contact angles, free

energies of adsorption, and Hamaker constants have been

successfully calculated. There is also some reason to

treat dipole-dipole interactions separately with the

geometric mean expression:

-9-

WA = 2^'1PY2

P (2.6)

The interaction energy between two dipoles is

2 ? 6 -2y, y? /3kTY,?, so if the distance between dipoles Y12

is the geometric mean of Y-.-, and Y-, « of the pure materials,

then Eq. (2.6) is correct.

The extension of Equations (2.4)(2.5) and (2.6) to

try to predict hydrogen-bonding with a geometric mean ex-

pression is quite incorrect, for hydrogen-bond acceptors

such as ethers, esters, or aromatics cannot themselves form

hydrogen-bonds and, therefore, y is zero for such materials,

even though these materials have a large W with hydrogen-

donors. Similarly, some hydrogen-donors such as chloroform

have zero values of y /but large values of W .

In solution studies, the separation of heats of mix-

ing into several terms soon followed. Blanks and Prausnitz

[9] used only two terms (polar and non-polar) while Gardon

[10] and Meyer and Wagner [11,12] included terms for dipole-

dipole and for dipole-induced dipole interaction. Although

hydrogen-bonding had been recognized much earlier [13-16],

it was Hansen [17] who brought forth the widely used three-

dimensional solubility parameter:

d p h AHM = AHR„ + AHM + AHM + (2.7) M M M M

and

S2 = 62 + 62 + 6? (2.8) a p h

-10-

_3 J

The dispersion force term (AH ), or more properly (AU ),

can be correctly evaluated by means of the geometric mean;

iHM » A0M " Vl*2(4+S2-2>/^f) (2-9)

and perhaps a dipole-dipole term (AU*j could also be esti-

mated from:

AUM = Vl*2(6l+62-2/^f> (2*10)

but for the reasons described before, there is no way that ■L. TTT—cr

AUM can be predicted with a term 2/6,62 and, consequently,

any two sets of correlations are in serious disagreement.

2-3. Acid Base Interaction

*■ Recently, Drago [18] has treated the hydrogen-bond as

an acid-base interaction (AH ) :

"iHMb = CACB + EAEB (2-11)

where

CA and CR = the susceptibility of the acid and base, respectively, to form covalent bonds.

EA and E = the susceptibility of the acid and base, respectively, to under- go electrostatic interaction

ab Drago measured AH„ in CC1. as a neutral solvent and deter- M 4

mined C, and E for each acid and C_ and E for each base.

He assumed that AH and AH*? were negligibly small for the

-11-

ab acids and bases, and in his correlation all predicted AH. M

values (up to 80 KJoules/mole) agreed with measured values

within about 5% or less.

Drago's correlation (treating interactions as due only

to dispersion forces and acid-base interactions) is much

more successful than Kaelble's [5] and Hansen's [17] corre-

lations (treating interactions as due only to dispersion

forces and polar interactions predictable from geometric

mean equations). It is of especial interest that in Drago's

correlation the neglect of dipole-dipole interactions gave

no problems, suggesting that dipole-dipole interactions are

negligibly small compared to acid-base and dispersion force

interactions.

Fowkes [19] proposes that the heat of mixing (AH ) be

given by:

AHM = PAVM + Vl*2(4-62)2-Xp(CACB+EAEB) + AU12 (2-12)

where X is the mole fraction of acid-base pairs per mole

of components present. Similarly, the work of adhesion

is:

WA = 2/fi*.- f(CACB+W * -noles °^cia-base pair

-' > W^ (2.13)

in which the constant f (near unity) converts enthalpy per

unit area into surface free energy, and the last term is

usually small.

-12-

These concepts combined with contact angle measure-

ments of liquids on the surface of solids lead to the work

of adhesion expressed as:

WA = YL(1 + COS 6) + 7re = WA + WAb + WA + "•• (2-14)

where Tre is any reduction of the surface energy of the solid

resulting from adsorption of the vapor of the test liquid.

Although Adamson [20,21] reported that a large contact

angle, in other words, a low surface-energy-solid, does

not necessarily imply a low fre; in general, ire is expected

to be negligibly small for high-energy liquids on low-

energy solids.

2-4. Kaelble Theory

As described before, Kaelble [5] proposed that inter-

facial tension between two phases can be expressed in the

following relation:

*12 = (a:Ta2>2 + <B1-B2)2 +712 (2-15»

= Yl + Y2 " 2/7T^ + 712 (2-16)

where a.. , $_ = square root of the respective (London)

dispersion Y,f and (Keesom) polar Y? parts of Y-,. Inter-

faces dominated by London dispersion interactions are

termed regular interfaces and the value of the excess term

A 2 of Eq. (2.15) can be considered negligible.

-13-

Kaelble's main concept is that the intermolecular

interaction can be expressed by two terms, dispersion com-

ponent and polar component, and both of them are expressed

with the geometric mean.

Surface tensions (y-j and y_) of phase 1 and 2 are:

y1 = a* + Bj2 (2.17)

y2 = a2

2 + B22 (2.18)

The work of adhesion (W ) between a liquid (L) and a solid

(S) is expressed as:

WA = 2(aLaS + BL3S) = YL(1 + COS 9) (2.20)

-14-

J

3. SAMPLE PREPARATION

3-1. Samples

3-1-1. Image Area and Non-Image Area of Lithographic Plates

For an image area, a commercial lithographic printing

plate, Kodak Polymatic Plate, was exposed by passing it three

times (net exposure time is 1.0 sec) under a Hanovia 200

watt/inch UV lamp. The exposed plate was cut into smaller

2 plates (3.3x2 cm ) and soaked in a soap solution for ten

minutes.u These plates were cleaned by the ultrasonic wave

cleaner (SONIFIER W-350 Bramson Sonic Co.), then rinsed

vigorously in the distilled deionized water by the ultra-

sonic wave cleaner again. These cleaned plates were dried

in a vacuum dryer for two and one half hours at room tempera-

ture, then kept in a desiccator.

For a non-image area, the photosensitive polymer

layer of the unexposed Kodak Polymatic Plate was removed

by Kodak Polymatic LN developer; then the plate was cut 2

into smaller samples (3.3x2 cm ) and rinsed vigorously with

the distilled deionized water by the ultrasonic wave cleaner

as well. These cleaned plates were dried and kept in a

desiccator in the same way as the image plate.

3-1-2. Photo-Oxidized Polystyrene Films

The 4.5 wt % of polystyrene (MW=35,000) solution was

-15-

prepared using methylene chloride as a solvent. This solu-

tion was applied on aluminum plates by a #18 wire-wound rod

applicator. These coated plates were kept in a vacuum

dryer for two and one half hours at room temperature. To

get various degrees of photo-oxidation of the polystyrene

films, the plates were exposed by passing under the Hanovia

UV lamp as many times as required to obtain the desired sur-

face energies, taking care that the temperature of a plate

would not rise above the thermal decomposition temperature

of polystyrene. The different degrees of photo-oxidized

polystyrene film were obtained by exposing as many times as

0, 30, 50, 100, 150, and 200. These plates were cut into

smaller samples (3.3x2 cm2) and kept in a dark box.

3-1-3. Dry Offset Ink Film

A commercial offset ink (SYN-DRY quick set black ink)

was applied, to an aluminum plate (3.3x2 cm2) using the Quick

Peek roller. The amount of ink on the Quick Peek plate

(20.2x5.5 cm ) was about 0.6g. These ink-coated plates

were dried for two and one half hours in an oven at 85°C.

3-1-4. Fountain Solutions

A commercial fountain solution (WESTERN TRI-FOUNTAIN

ETCH) was diluted with distilled deionized water to differ-

ent concentrations (0.2, 0.5, 2, 8, 20, 50 vol %) so as to

get a series of different surface tensions. However, the

-16- A

diluted fountain solutions had to be used within 24 hours

since they were unstable. Some sedimentation took place at

the bottom of the solution if the solution was kept for more

than 48 hours at room temperature.

3-1-5. Surfactant Solutions

Since anionic surfactants are unstable at low pHf a

cationic and a nonionic surfactant were examined.

(A) Cationic Surfactant

Hexadecyltrimethylammonium bromide (C,gH33N(CH3) Br~;

-4 C.M.C. = 9.2x10 M) was used as a cationic surfactant.

Three different concentrations of cationic surfactant solu-

-4 -4 -3 tion (1.57x10 M, 5.49x10 M and 1.10x10 M) were prepared.

The pH value of the solutions were adjusted to 3.0 by

phosphoric acid.

(B) Nonionic Surfactant

Isooctylphenoxy polyethoxyethanol (TRITON X-100; _3

C.M.C. = 1.25x10 M) was used as a nonionic surfactant.

Three different concentrations of nonionic surfactant

solutions (3.30xlO~6M, 3.30xlO""5M and 1.24xl0~"3M) were

prepared. The pH value of the solutions were also ad-

justed to 3.0 by phosphoric acid.

3-1-6. Gum Arabic Solutions

As one of the modified fountain solutions, three

-17-

different concentrations of gum arabic solutions (0.2 g/%,

1 g/% and 2 g/%) were prepared by dissolving 2 g of gum

arabic (Meer Gum Arabic Type G-150) in one liter of dis-

tilled deionized water at 60°C for three hours. The pH

was also adjusted to 3.0 by phosphoric acid.

3~2. Surface Tension of the Solutions

The surface tensions of the solutions were measured

by the Du Noiiy Ring method. The temperature of the solu-

tions was 23 ±0.5°C. These results are tabulated in Tables

3.1-3.4. The pH values of the solutions are also indicated,

Table 3.1. Surface tension and pH of the diluted fountain solution.

Concentration Surface Tension pH Vol % Wt % mN/m

0 0 72.3 5.9

0.2 0.05 66.5 3.48

0.5 0.14 58.5 3.20

2 0.55 53.0 2.92

8 2.2 42.7 2.64

20 5.5 38.0 2.46

50 13.7 34.2 2.23

100 27.3 34.2 2.07

-18-

Table 3.2. Surface tension and pH of the cationic surfactant solution,

(hexadecyltrimethylammonium bromide)

Concentration g/£ mole/£

Surface Tension mN/m

PH

0.057 1.57X10-4 59.4 3±0.1

0.2 5.49X10"4 44.5 3±0.1

0.4 l.lOxlO"3 38.5 3±0.1

Table 3.3. Surface tension and pH of the nonionic surfactant solution.

(Triton X-100)

Concentration q/l mole/Z

Surface Tension mN/m

PH

2.3xl0~3 3.30xl0~6 51.5 3±0.1

2.13xl0~2 3.30xl0~5 35.7 3±0.1

8.0X10"1 1.24xl0~3 31.7 3±0.1

Table 3.4. Surface tension and pH of the gum arabic solution.

Concentration Surface Tension mN/m

PH

0.2 64.5 3±0.1

1.0 62.0 3±0.1

2.0 61.0 3±0.1

-19-

3-3. Interfacial Tension

3-3-1. Method

The interfacial tensions of octane and the fountain

solutions were measured by the drop weight method [22J,

There are several methods [23] to measure interfacial

tensions; however, the drop weight method was applied since

this method is the most accurate and relatively simple of

the available methods.

The relationship for calculating interfacial tensions

in terms of drop weight may be expressed as;

where

W = 2TrrByf (r/V173) (3,1)

W(mg) : the weight of a drop

r : the tip radius a

f (r/V1/'3) : the correction factor

so, the interfacial tension Y: »

Y = {v|P;L-p2|g/rB}-F (3.2)

where

V : the volume of a drop

p, : the density of a phase 1

p2: the density of a phase 2

F : the correction value related to r/V '

The correction factor, F, is in Table VI-B (Matijevic,

Surface Colloid Science Vol. 1) [22].

-20-

3-3-2. Density of the Solutions

The density of the solutions was measured by weighing

a known volume (50 mi) of the solution at 23°C. The results

are tabulated in Table 3.5.

Table 3.5. Density of the fountain solutions,

\ Density g/cm

Water 0.9978

0.2 Vol % 0.9978

0.5 0.9983

2 1.0001

8 1,0092

20 1.0274

50 1.0694

3-3-3. Calibration of the Traube Stalagmometer

The Traube Stalagmometer (HELLIGE INCORPORATED) is

essentially a pipette with a broad flattened tip which per-

mits large drops of reproducible size to form slowly and

finally drop. The stalagmometer tube 1211-B was used for

these experiments.

In order to calibrate the apparatus, the volume V

and V, was determined by weighing the volume of water, V_,

V_ and V_ (Fig. 3.1). The result is:

-21-

>

o

PQ

LFf

u •P

§

rH

•P CO

a)

m

•H En

-22-

Therefore,

VA = 4.2513 g/p (water)

VB = 4.4085 g/p (water)

Vc = 4.6987 g/p (water)

VQ = 4.1009 g/p (water)

V, = 0.03779 g/p (water)

3-3-4. Result

As for the interfacial tension of octane and fountain

solution, the time-dependence after contacting two liquids

was found by pre-experiment. Octane is insoluble in water;

however, octane dissolves some surfactant in the fountain

solution. Then, if this octane is used for a different

concentration of fountain solution, a different value of

interfacial tension will be obtained, compared with the value

by using fresh octane since this used octane contains a Urn

certain amount of surfactant depending on the concentration

of the previous fountain solution contacted. The volumes

of the phase 1 (fountain solution) and the phase 2 (octane)

were about 200 m£ and 75 mi, respectively. The measurement

of the interfacial tension of octane and water was done

first. This octane was used for the next measurement for

0.2% fountain solution. Then, this octane was used for

0.5% fountain solution and then up to 50% fountain solution.

These results are tabulated in Table 3.6 and compared with

theoretical values.

\ ■

-23-

C cd •P O O

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^ CN

CN g 00 C\ m CN CO r4 CO rH

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w 0 U fe

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-24-

The theoretical values of the interfacial tension were

calculated as follows:

*12 = Yl + Y2 - 2/yf Y2d (3.3)

There is only a dispersion force working between two liquids

where one of them is octane, as mentioned in Chapter 2-1.

However, it is provided that the dispersion component of

the fountain solutions is the same value as 21,8 mN/m

value for water. Some discussion on this problem will be

given in Chapter 4-2-2.

-25-

4. SAMPLE CHARACTERIZATION

In order to characterize solids in terms of surface

energetics, Zisman [24,25] and others [26-29] did intensive

work on the critical surface tension. However, to deal with

the critical surface tension is quite empirical, but not

theoretical. Several others [30-36] tried to determine the

surface tensions of solids and liquids which comprise the

dispersion component and non-dispersion component, and to

correlate experimental results with theory.

4-1. Dispersion Component and Non-Dispersion Component of Solids

4-1-1. Method

According to the theory of Fowkes, the work of ad-

hesion can be described as follows:

WA = WA + WAb + WA + C4-1)

when methylene iodide is used as the standard for deter-

mining the y values:

*CH2I2 = *CH2I2 "

50-8 mJ/m2 <4-2)

Since the work of adhesion of solids and methyleneiodide

comes only from the dispersion force, the values of Ys

have been established as follows from contact angle

-26-

measurements of CR^l? on s°U-ds<

WA " WA " YCH,I, <* + COS 9) " 2/YCH,I 4 <4'3)

2. 2. Z S

■ {T

CH2I2U

+ cos ft>}2/4T! Y

S = rcH,i,<i + c°s s->r/4YcH2i2 <4-4»

a-bromonaphthalene, which is also considered to have only

d 9 a dispersion component (y =44.6 mJ/m^) , was used to Li J

determine the values of y .

By contact angle measurements of water on solids, the

value of W^ + W^ - TT (this term is called the non-dis- A A e

persion interaction energy, IqWf in the case of water) can

be defined. From Equation (2.13):

wai> + WP-TT =1 =Y(1 + cos 6) - W (4.5) A A e SW i/ ; A l*. 3/

= YL(1 + cos 9) - 2AgY^ (4.6)

4-1-2. Image Area and Non-Image Area of Lithographic Plates

A sample was placed in a cell (rame-hart, inc), which

is made of metal and has two glass windows so that light

can penetrate through the cell. Sessile drops of a liquid

on the Image Area were formed with a pipette, and the cell

was sealed by the lid; the contact angle measurements were

made of both sides of each drop with a goniometer. The

size of the drops was more than 3 mm diameter to avoid

the effect [37] of the nonuniformity of the solid surface.

-27-

In the case of water drops, a small amount of water was

placed in the cell beforehand in order to avoid the evapo-

ration of water from water drops and ensure that the water

vapor pressure reached equilibrium as quickly as possible

after sealing. The average value was calculated by the

measurements of at least six drops,

For Non-Image Area, the same procedure was used. The

results are tabulated in Table 4.1.

Sharpies [38] reported that the plastics whose surface

free energies are larger than 38 mJ/m2, adhere to the ink

well. The surface free energy of the Image Area is also

o d larger than 38 mJ/mz. The experimental value of Y_ of the

Non-Image Area, AI2O3, seems small compared with those of

other metal oxides determined from gas adsorption [39] . \

Kaelble [5] reported that the value of YC of News-paper

plate (pre-sensitized 3M Type "S") was 25.5 mJ/m''. This

value is much smaller than the value obtained in this study.

The contact angle of methylene iodide and a-bromonaphthalene

on the Non-Image Area was also measured in water; the dis-

persion energy was 47.0 mJ/m2 and the non-dispersion inter- 2

action energy with water was 109,0 mJ/m , Judging from

these results, the value of y^ of anodized Al203 may be

about 50 mJ/m2. The wetting properties of the Non-Image

Area with respect to the contact angle and dye adsorption

capacity have been dealt with by Severn [40]. However, he

did not explain it in terms of surface energetics.

-28-

r-

,_^ CN

g CT> <Ti to o <T*

K/S ^ • • • • »

S «2 rH ■<* O H 1 ro £ (Tl 00 00 O 1 ■^

rH rH

CJ o CN •H ^ e r^ r^ +J to \ I 1 • • O H »"D | 1 o 1 1 r^ fd £ C\) 1 1 i^ U

C (d •H 0 . .

U <X3 CO CN G < J- 6 O O \ • 1 r I -H (D > h> iH 1 i 1 to tr> < g, •<* Vt <d <D g CUH W 1

•H G ^^ 'd o <N

1 ^ e V© ^ CO c TJ CO \ • • • r 1 o fd >- *s rH o o i t C G £ •^ ■># in

(d 13

<d en a fd rH

+> e tn fi H C <D •< CJ *H O ro in o o 0 0 -P o • • • • • a O — «JD IT) n CO o 00 e >i rd CO CN CO O tn -P O H G

<D o fi C u 0 <u

•H (0 <D <D fc a C Q) 0) <D & rH rH 10 cd (d

■H si A Q •P

a, -p

ft V • rd (d rH G C • o o vf 6 e

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EH o a & O 3 5

<D CP

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o 53

-29-

4-1-3. Photo-Oxidized Polystyrene Films

The same procedure was used for the surface energetic

characterization of the photo-oxidized polystyrene films.

The values of yq were determined by only methylene iodide.

The results are summarized in Table 4.2.

Table 4.2. Surface energetic characterization of photo-oxidized polystyrene films.

Sample d YS •W WA

mJ/m2 mJ/m mJ/m

0-3 48.3 9.0 73.9

30-3 45.5 16.4 79.4

50-3 47.5 23.7 88.1

100-3 45.0 40.6 103.2

150-3 44.6 69.1 131.4 ,

200-3 43.8 71.4 133.2

0-4 47.0 12.1 76.1

30-4 47.0 20.9 84.9

50-4 46.9 28.3 92.3

100-4 46.6 47.6 111.4

150-4 44.2 66.6 128.7

200-4 43.9 71.8 133.7

The first number of the sample stands for the number of

passes under the UV lamp and the second for the lot number

-30-

of the sample.

The results indicate that the dispersion component of

polystyrene decreases only slightly as the exposure time

increases. The non-dispersion interaction, on the other

hand, increases greatly owing to the photo-oxidation. After

irradiation by UV light, carboxylic acid groups were found

on the surface of the polystyrene film [41] . Therefore,

the photo-oxidized polystyrene film becomes more hydro-

philic with increasing exposure times.

Figure 4.1 shows the linear relationship between Ig

and WA, indicating that the non-dispersion interaction

energy increases with increase in degree of photo-oxidation

without changing the value of y„.

4-1-4. Dry Offset Ink Film

When ot-bromonaphthalene was dropped on the dry ink

film, the contact angle of the drop changed with time,

becoming smaller and smaller. After four minutes, the con-

tact angle became constant. However, on the surface of the

drop, an oil film which may have been extracted or dissolved

by ot-bromonaphthalene from the ink film was observed.

Therefore, the true value of Yc should be calculated from

the data with methylene iodide. The results are tabulated

in Table 4.3.

-31-

C\J

E ™

CD

X o _o "o sz o. cz o

CD

<T3

O

CD cz CO

< o ro cz cz

o c o o

CD E o

< M— o

cz

o ro

E .E o o t/»

"to _.

CD C Q_ CD

cz >* o o

( uj/rw > ^ V

+ v

quM

-32-

;

Table 4.3. Surface energetic characterization of dry ink film.

Contact Angle d

YS ■""SW WA

e,° mJ/m2 mJ/m2 mJ/m2

CH2I2 58.1 29.7 — 77.6

a-bromo 8.0 44.2 — 88.8

Water 105.6 — 2.0 52.9

4-2. Dispersion Component of Liquids

In order to define the values of the dispersion compo-

nent of the fountain solutions, two standard solids were

chosen, paraffin wax and polyethylene, which have mainly

the dispersion component.

4-2-1. Characterization of Paraffin Wax and Polyethylene

The dispersion component and the non-dispersion inter-

action energy of these two solids were deterjaiaesL iy the" 'V

same method described in Chapter 4-1-1.

Paraffin wax films were prepared by dipping a cleaned

aluminum plate into the hot melted paraffin wax and cooling

it at room temperature. For the polyethylene film, poly-

ethylene was dissolved in toluene at 85°C in 8% concentra-

tion. Cleaned aluminum plates (3.3x2 cm2) were dipped into

the solution and dried in a vacuum dryer for two and one

-33-

half hours at room temperature. After drying, the plates

were kept in a dark box.

The results are tabulated in Table 4.4.

Table 4.4. Dispersion component and non-dispersion interaction energy of paraffin wax

and polyethylene.

CH2I2

e,°

Water yt mJ/m2

Jsw mJ/m2

WA

mJ/m2

Paraffin Wax

Polyethylene

66.9

62.4

109.3

107.5

24.6

27.2

2.1

1.9

48.4

50.6

Although the non-dispersion interaction energies, ICrTf be- t>W

tween the solids and water are quite small, they exist.

4-2-2. Dispersion Component of the Fountain Solutions

The dispersion component of the fountain solutions

(Lot NO. 1) was determined by using paraffin wax as a model

solid. For the fountain solution (Lot NO. 2), polyethylene

was used for this experiment. The results are summarized

in Tables 4.5 and 4.6. The values of yT were calculated

assuming that there is no non-dispersion interaction be-

tween the solids and the fountain solutions. The average

values of yT were determined from Fig. 4.2.

Judging from these results, it seems that the dis-

persion component of the fountain solutions increases with

increasing concentration. However, negative values of the

. -34-

Table 4.5.* yT of the fountain solutions

(Lot N0.1) from paraffin wax.

0.2 Vol % 0.5 2 *

8 20 50 100

YL (mN/m) 68.7 63.5 58.7 48.0 43.1 37.0 34.5

Contact Angle 0,° 109 92.3 96.0 85.0 74,9 60 50.4

3 / -r / 2X YL (mj/m ) 21.0 36.4 27.1 26.7 28.9 30.2 31.3

AV YL (mJ/m2) 22.7 24.0 25.3 28.0 29.2 30.6 31.2

Table 4.6. YT °f tne fountain solutions

Li

(Lot NO. 2) froir i polyethylene.

0.2 Vol % 0.5 2 8 20 50 100

YL (mN/m) 66.5 58.5 53.0 42.7 38.0 34.2 34.2

Contact Angle 8,° 105.2 95.9 87.3 74.2 56.8 49.2 49.3

Y£ (mj/m2) 22.1 25.3 28.4 27.1 31.8 29.4 29.4

AV YL (mJ/m2) 23.3 25.8 26.6 29.3 30.5 31.4 31.4

non-dispersion interaction energy between Kodak Image Area

and the higher concentration of the fountain solution were

obtained when using the values of YT which were calculated Li

from this experiment. It is impossible that the dispersion

interaction energy is larger than the total interaction

energy between two substances.

-35-

80 CVI

- 60 CD c o £ o o >-, en i_ CD

CD O CO

M— S—

40

20

0

Total Surface Energy,

Non-dispersion Surface E

Dispersion Surfa Energy

0 20 40 60

Surface Tension ( ml\l/m )

Fig.4.2 Dispersion force component of fountain solution from contact angle on Paraffin and Polyethylene Paraffin ; o Polyethylene ; A

80

-36-

Table 4,7 shows the calculated values of I0 __ from b.ilb

the contact angle measurement of the fountain solution (Lot

NO. 1) on Kodak Image Area in air. The values of average

YT were used for this calculation.

Table 4.7. Non-dispersion interaction energy, Ic „c,

calculated by using average Yps»

0.2 Vol % 0.5 20 50 100

JS.FS (mJ/m2) 18.8 21.8 22.1 9.6 3.7 -4.0 -6.7

These negative values obtained are probably the result,

not only of disregarding the non-dispersion component of

paraffin wax or polyethylene, but also the adsorption of

surfactants or gum arabic in the fountain solution on the

solids. Therefore, the values of y„c calculated from these

experiments are apparent values. Since the fountain solu-

tion consists of several chemicals, the dispersion component

of the fountain solution cannot be defined by measuring

contact angle of the fountain solution on paraffin wax or

polyethylene. However, the value of the dispersion compo-

nent of the fountain solutions may be defined as the same

value as that of water, 21.8 mJ/m . This value may not be

far from the true value. Therefore, this value, 21.8 mJ/m2,

was used as the dispersion component of the fountain

solutions for surface energetic calculations.

-37-

5. - CONTACT ANGLE MEASUREMENT

Two methods of contact angle measurement besides in

air were carried out to determine the interaction energy

between solids and liquids. One method is to measure the

contact angles of liquids such as water and the fountain

solutions in octane medium. The other method is to measure

the contact angle of octane in a liquid media such as water

or the fountain solutions. In the latter case, an octane

drop was applied, on the solid using a syringe with a

hooked needle.

The schematic diagram of these measurement methods is

shown in Figure 5.1. The interaction energy from these

experiments can be calculated as follows. For the contact

angle of liquids on solids in octane medium:

Y0.L COs9= YS.0 " YS.L (5-1)

»,«•■ * -= Yo + Y~ ~ 2/YCY_ - IT S'O

- <VYL-2^-*f-Wj) (5.2)

Y0 ~ 2/ySY0 " YL + VWL

+ (W^b + wP - 7re) (5.3)

-38-

octane

A aqueous liquid

777/7777777- solid Y S.L Y S.O

<LF solid

octane

th aqueous media

O.L

Fig. 5.1 Schematic diagram of contact angle measurement in both water and octane phases.

-39-

\

Ô-2-^- *L + 2l/V^+IS.L (5"4>

where

Y0 L = the interfacial energy between octane and the liquid

Y_ n = the interfacial energy between octane b,u and the solid

Yq j = the interfacial energy between the solid and the liquid

I_ L = the non-dispersion interaction energy between the solid and the liquid

7T = the film pressure due to the adsorption of water vapor in air

TX should be considered when the solid has a high surface

energy. The effect of water vapor adsorption in air con-

tributes to the non-dispersion interaction energy even if

the solid is immersed in octane. The work of adhesion can

also be calculated as follows:

WA = Y0.L + ^S.O " YS.L (5'5)

= Y0 L (1 + cos 6) + ire (5.6)

For the contact angle of octane on solids in liquid media:

y0Jj cos 6 = YS.L - YS.0 (5.7)

. 0 /d d r-rS't) TTP = YS + YL-2/YsYL - WA -WP

o /d~d - <Ys+Y0-2/YsY0 " V (5.8)

-40-

0 /d~~d , 0 /d~d YL ~ 2/VL " Yo + 2/¥o

- (W^b + WP - TTe) (5.9)

/d~d ^ 0 /d; d /Y^Y, - Y~ + 2/Y " ^L-^VLÔ^VO-^L (5'10)

WA = YS.L + YO.L " YS.O (5-i:L)

= Y^ T (1 + cos 9) + TT (5.12) 'O.L e

5-1. With Water

Water was used as the liquid and the photo-oxidized

polystyrene films were used as the solids. The value of

the contact angle 9, the work of adhesion W , and the non-

dispersion interaction energy between water and solids are

tabulated in Table 5.1

In Figure 5.2, these results are superimposed on

Figure 4.1, which shows the relationship between the work

of adhesion in air and I of the photo-oxidized poly-

styrene film. The values of l_, measured in octane media Sw

have values close to those measured in air, whereas the

Values of I measured in water media have much larger

values than those measured in air, except the non-photo-

oxidized polystyrene film. The values of Igw measured in

octane by water drop are smaller than the values measured

in air for the low degree of photo-oxidized polystyrene

-41-

Q) C Q) U >i -P • 01 *H >i Q) M -p O (0 P4 S

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to C (0 O a)

■H e ■P O u (d a) JH •P <D « -P £ c -HX:

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-43-

films; however, Igw increases and becomes larger than the

values in air for higher degrees of photo-oxidation of the

polystyrene films. The difference between these two values

of I for the latter case may be explained by the IT

effect. The values of I_ from the octane drop on the poly-

styrene film in water media increase strongly from almost

the same value as in air up to 90 mj/m • Since these values

are calculated from advancing contact angles of octane, i.e.,

receding angles of water, the values are larger than those

obtained in air in most cases. This phenomenon indicates

that the octane drop behaves on the polystyrene films as if

the polystyrene films had large values of Iq„ compared with

those measured in air or octane media. Therefore, as

Hamilton [42,43] suggested that the hydrophilicity of a

solid can be characterized by this method, the value of

Iq is quite sensitive to hydrophilicity of the solid,

especially in the region where the solid has a small value

of the non-dispersion component.

The same procedure was used for Imaê Area and Non-

Image Area. The results are tabulated in Table 5.2 and

compared with the values obtained in air.

In the case of Image Area, the value of Ig in octane

media was almost equal to the value in air. On the other

hand, the value of I__7 in octane for the Non-Image Area

is much larger than that in air. These values are also

shown in Figure 5.2. This difference in I_w of the

r- -44-

ti G (d

cu n Di CU id •p e (d H £ in G o •H

s^d tr> G ^ td o G cu 0 G

td G -P o o

-H O •p o G td •H U o CO -P id G cu

•H u <

G O o •H Cn 0) td M £ CD H ft l 10 G

•H 0 13 3

1 G o z

• CM

• in

<D iH A td EH

Non-Image

in air

•

cu tn td e H

1 G O

32.3

93.2

93.2

175 0.19

100.8

Image in

air

« o CM

0)

td e 1

23.9

22.3

22.3

105.8

36.7

64.3

^ CM CM g

a s O —'

•* r< CO CD & H

^-s CM CM g

a & IS

- < CO CD ^ M

Water drop

in

Octane

Octane drop

in

Water

-45-

Non-Image Area can be explained by the change in the u

value. In the case of the octane media, the value of IT is e

relatively small since the sample was immediately immersed

in octane after removal from the desiccator. On the other

hand, the value of TT in air is relatively large since the

cell was sealed after making a sessile drop on it. By

exposing water vapor in the sealed cell for more than ten

minutes before the sessile drops of water were formed on

the Non-Image Area in octane media, the value of I_ up to

54.6 mJ/mz (AV 0 = 73.8°; water drops in octane media) was

observed. Therefore, the increase in the IT value due to e

water vapor exposure is 38.6 mj/m compared with the value

without water vapor exposure provided that the value of y

of the sample exposed by water vapor had not been changed.

5-2. With Fountain Solution

5-2-1. In Air /

The sessile drop of the fountain solution was formed

on solids (the photo-oxidized polystyrene films, Image

Area, Non-Image Area, and dry offset ink film) in air.

The results are shown in Figure 5.3. An interesting

observation can be seen. When a solid is highly hydro-

phobic, the contact angle decreases as the surface tension

of the fountain solution decreases. However, if a solid

has a relatively large non-dispersion component except the

Non-Image Area, the contact angle tends to increase to a

-46-

Q^

CD

CD c

o

o O

30 40 50 60 70 80

Surface Tension ( mN/m )

Fig.5.3 Contact angle of fountain solution on solids in air

-47-

maximum and decrease again. In the case of the Non-Image

Area, the contact angle tends to decrease moderately with a

decrease in the surface tension. As the surface tension of

the fountain solution decreases, the contact angles tend to

converge regardless of degree of hydrophilicity of solids.

5-2-2. In Octane

The average contact angle 8, I_ „_ and the work of'

adhesion for the Image Area and Non-Image Area are tabulated

in Table 5.3 and for the photo-oxidized polystyrene films in

Table 5.4. For Tables 5.3 and 5.4 the calculated inter-

facial tensions between octane and the fountain solutions

from the theoretical equation were used.

Figure 5.4 shows the change in contact angle as a

function of the surface tension of the fountain solution.

For the photo-oxidized polystyrene film composed mainly of

the dispersion component, the contact angle was almost con-

stant or slightly increased as the surface tension decreased.

For solids with a high non-dispersion component except the

Non-Image Area, the contact angle increased first and then

decreased. This trend is similar to that obtained in air

with the fountain solution for the highly photo-oxidized

polystyrene film. For the Non-Image Area, the contact

angle constantly decreased as the surface tension of the

fountain solution decreased. The behavior of the Non-Image

Area and the highly photq-oxidized polystyrene films for

-48-

<D t^ (d e • H 05

c »H O O -H

+> C 3 O H

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o in rH rH CO CO CO 00 in in in ■** ** r~ en en CM o o CN m

rH rH CM rH

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00 rH CN CM ■■# "* •*J« 00 00 00 r- en en m CO 00 r^ r^ r-» in ■sr CM Cn rH rH r^ CM CM r- CM CM rH rH rH

O Ch <S\ CT> r- r- r- •^ ^* 00 CO CO ^j» in in vo o o

CM in CN CM •<* in m rH o o co CO co CO t^ r- en r^ r^ in -* CO rH rH o CM CM r- co co m •* rr rH rH rH rH

rH CN CM O VD VO O 00 00 in r^ r» m co CO 00 CM CM in

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rH rH CO rH

rH rH <T> co co VO in in in in in

<x>

rH CX> rH rH CO r- r- 00 CT» en VO en en co in in CO r^ r» o > 00 CO CO CM en en rH rH rH VO o o in in in o in m

in "tf CM CM CM en •** "tf VO VO VO in r*» r- CM rH rH rH

O

u O r- r- O r-» r^ VO CO CO *& CO co ■<* r» r^ in in in CD

■P in •«* "^ CN o o 00 VO VO rH en en rH ■^p ^r CO o o rd in •>* rH rH rH CN CM en •«*• ^r VO t^ r- in 00 00 & rH rH rH

• i *—* ^—* ^^ ^^H «—* CM CM CM CM CM CM

g g 6 g e g "V, .-» ^ *—* ■^ «*^ *—* ^s «M^ \ ^■^

fO CM io CM h> CM h> CM ^ CM ^ CM g g g g g g g 6 g g g g

o •^

o w O w hi

o h)

o w o

•» w g ^ w g «h w g *» CO g ^ CO g ^ CO g © En — © |X4 *"■"' © Jx, **"' © fc >~' CD fe-- © h'-'

• « « • * 1

> CO < > CO ► •< J> M ^ > CO < > CO < > CO <

< H & < H & "U H & < H & < H & < H &

CO CO CO co CO CO 1 1 1 1 1 1 o O

CO O in

o o rH

O in rH

o o CM

-50-r

180

160

140

120

<c> 100

CD

cn c: <

o CO

o o

40-

20 Non-Image

Ohtf-* 30 40 50 60 70

YF. S. ( mN/m )

Fig. 5.4 Contact angle of fountain solution on solids in Octane

-51-

this experiment is quite different even though they are

both hydrophilic. The reason for this is unknown; however, v

it may be the difference in their nature, the Non-Image

Area (AlÔo) being basic, and the photo-oxidized polystyrene

film being acidic. Therefore, the acid-base interaction

between the acidic fountain solution and the basic Non-Image

Area is greater than that between the acidic fountain solu-

tion and the acidic photo-oxidized polystyrene film. The

fact that the photo-oxidized polystyrene films and the Image

Area are acidic has been proven by dyeing with Nile plue or

Methyl Violet. The color of the polystyrene films and Image

Area which were dyed by Nile Blue was reddish-blue and the

density of color of the films increased with the degree of

photo-oxidation. However, Tetrabromophenolphthalein Ethyl

Ester for basic sites could not dye the Image Area or poly-

styrene films. This indicates that only acidic sites exist

in the photo-oxidized polystyrene films and the Image Area.

Figure 5.5 shows the work of adhesion and I_ pg as

a function of the surface tension. In this case, the work

of adhesion has the same value as I„ „„. The work of ad- fa . £ o

hesion as well as I0 _„ decreased constantly as the surface

tension decreased. However, this decrease is mainly due

to the decrease in the interfacial tension between octane

and the fountain solution.

-52-

CV!

40 50 60

YF.S. ( mN/m )

Fig. 5.5 Work of adhesion and non-dispersion interaction energy of fountain solution on solids in Octane

-53-

5-2-3. In Fountain Solution

A sample was immersed in the fountain solution, and an

octane drop was released from a syringe with a hooked needle

to deposit on the inverted sample surface, one minute and

five minutes after immersion.

For the Image Area and Non-Image Area, the results

after one minute immersion are tabulated in Table 5.5. For

the photo-oxidized polystyrene films, the results after one

minute and five minutes immersion are tabulated in Table

5.6.1-3.

In Figure 5.6, the contact angles after one minute

immersion are plotted as a function of the surface tension

of the fountain solution. The contact angles for solids

which have mainly the dispersion component remained con-

stant or decreased slightly; on the other hand, the contact

angle for the highly photo-oxidized polystyrene increased

with increasing concentration of the fountain solution as

expected. Figure 5.7 shows the change in contact angle

after five minutes immersion.

In general, the contact angles are shifted to higher

values after five minutes immersion. Generally, the con-

tact angle increased and leveled off at about 50 mN/m

(corresponding to 2 vol %) surface tension. So, a fountain

solution at more than 2 vol % concentration would be useful

in terms of adsorption of water-soluble polymer such as

gum arabic contained in this commercial fountain solution.

-54-

/I*. ;

MH ox:

-P c -H o s

•H w w (U c x: o <d -H (0 +>

3 • <H rH C o o O

tn -H x W u C H O-H <D £ rt g

+) g •a c •H c a (0 o a)

m -P >i P Cn <D G MX5 -H (D -P g C <D C (D

•H C G O O (0 •H (D ?H •P M a) O f0 -P (0 m u o rd <D tn •P td <u C g C •H H rd

1 ■P c c o o o O •H -S (0 H V4 <u o & to a)

-H CP T3 rd

i g C H o !3

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in

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oo O CO CO rH o • • • • • m CM CO ■H in •^r o

as rH rH CM

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as iH rH rH

CO

o r- rH r- r-t • • • • •

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co CM CM CO T-i • • • • •

CM r- in r^ in CM o en CO CM

rH VD

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-56-

rH o CO in r-> rH •"* ro in 00 00 o o r- 00 VO in r- r> rH ro rH VO CO rH in rH

rH rH rH

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Q>

cr> C <

o CO

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180

160

140

120

100

80

A 150-3 *

Non-Image 200-3

A £ -

100-3 •

50-3

Image

o

30-3

40

20

Ohtf- 30 40 50 60

YF.S. < mN/m )

-O O

70

Fig. 5. 6 Contact angle of Octane on solids in fountain solution after 1 minute immersion

-59-

CE>

CD

en C <

o CO

c o O

30 40 50 6fi 70

YV.s. ( mN/m )

Fig. 5. 7 Contact aTigle of Octane on solids in fountain solution after 5 minutes immersion

-60-

It was reported [44] that a contact angle of 165-170° is

needed to repel printing ink from non-image area. There-

fore, the highly photo-oxidized polystyrene film, for ex-

ample 200-3, may be used as a non-image area when 2 vol %

fountain solution is used.

The contact angle for the Non-Image Area is constant

and quite high independent of the surface tension of the

fountain solution. In this case, the octane drop can

hardly be in contact with the plate since the interaction

energy is very small. An octane drop slides away on the

plate if the plate is slightly slanted. From this experi-

ment, it was not determined whether gum arabic adsorbed

on Non-Image Area because the contact angle is so large,

even for pure water.

Figure 5.8 shows the work of adhesion and the non-

dispersion interaction energy as a function of the surface

tension of the fountain solution. The work of adhesion,

as well as the non-dispersion interaction energy, decreased

with the decreasing interfacial tension since the contact

angle is relatively constant.

5-3. With Surfactant Solution

5-3-1. Cationic Surfactant

Sessile drops were formed on the solids in air, and

their contact angles were measured. The results are shown

in Figure 5.9. The same trend as observed for the

-61-

>-

«v i/rui ) 'S'd s

CD c CO

"o O

>-* en i_ CL> c

c JO

"o CO I— CD

c o v_ a>

ô •—

O o C bo

■a c

CO ro

.— o cr> *•—

CO ^

o

oo

( uj/ruj) M

-62-

C£>

ct> en d

o to d o o

50 60

rL l mN/m )

Fig. 5.9 Contact angle of cationic surfactant solution on solids in air ( Hexadecyltrimethylammonium bromide )

-63-

r

commercial fountain solution in air was observed except for

the Non-Image Area. For the Non-Image Area, the contact

angle increased to a maximum and then decreased again.

In octane media, sessile drops of cationic surfactant

solution were formed on the solids (Fig. 5.10). In this

case, the contact angle increased strongly with increasing

surfactant concentration without exception as compared with

the case of the fountain solution. Even for Non-Image Area,

there was no change in contact angle down to a surface

tension of about 45 mN/m; however, the contact angle abruptly

increased for lower surface tensions.

As it is said that cationic surfactants make everything

hydrophobic, the apparent hydrophobicity of a solid increases

with an increase in the concentration of cationic surfactant

solution.

There is also an interesting trend in the contact angle

of octane on the solids in cationic surfactant solution (Fig.

5.11). The contact angle decreased with increasing concen-

tration to a minimum and then increased, except for the

Non-Image Area where contact angle did not change at all.

The more hydrophilic the solid is, the faster the con-

tact angle increases and reaches to the constant valueôf

about 170°. Therefore, the octane drop behaves as if the

solid were more hydrophobic up to a certain concentration

of cationic surfactant and then became more hydrophilic

for a higher concentration. This trend may be explained

-64-

<£>

CD

o

cz o o

YL ( mN/m )

Fig. 5.10 Contact angle of cationic surfactant solution ( Hexadecyl trimethylammonium bromide ) solids in Octane

-65-

180

CD

CD

CD C

o to

o O

160

140

120

100

/**J ns

40

20

0 h*P

Image

40 50 60

YL ( mN/m )

70

Fig. 5.11 Contact angle of Octane on solids in cationic surfactant solution ( Hexadecyl trimethyl ammonium bromide )

-66-

by considering the number of adsorption sites on the sur-

face of a solid and the cationic surfactant concentration.

The highly, photo-oxidized polystyrene film has a large j

number of adsorption sites, whereas a highly hydrophobic

solid such as non-photo-oxidized polystyrene film has only

a few adsorption sites. The adsorbed cationic surfactant

makes an adsorbed film which is a barrier that prevents the

actual contact of the octane drop and the solid. For

sample 200-4, the barrier formation is easier than for the

sample 0-4, which has an adsorbed cationic surfactant film

not thick enough to prevent contact of the octane drop with

the true surface, even at a concentration of 1.10x10

mol/Jl.

(

5-3-2. Nonionic Surfactant

The contact angles of the nonionic surfactant solution

on the solids in octane and of octane on the solids in the

nonionic surfactant solution were measured.

In the case of the octane medium, the contact angle

of the nonionic surfactant was almost constant or increased

slightly with decreasing surface tension. However, at a

low surface tension of about 32 mN/m, the contact angle

decreased abruptly (Fig. 5.12). Except for this abrupt

decrease in contact angle at low surface tension, this

trend is the same as that observed from the experiment

with the commercial fountain solution. For the Non-Image

-67-

180

Fig. 5.12

30 40 50 60 70

YLOf Nonionic Surfactant Solution ( mN/m )

Contact angle of nonionic surfactant solution { Triton X-100 ) on solids in Octane

-68-

Area, the contact angle at surface tension 32 itiN/m is as

low as 4°, indicating that the nonionic surfactant solution

spreads on it and can repel octane from the surface. How-

ever/ at this condition the contact angle on the Image

Area also decreased from about 125° to about 55°, which

indicates this concentration of nonionic surfactant solu-

tion makes Image Area hydrophilic. Therefore, the nonionic

surfactant solution at this high concentration cannot be

used as a dampening solution.

In the case of the octane drop on the solids in the

nonionic surfactant solution, the contact angle of octane

remained constant or decreased slightly with increasing

.nonionic surfactant concentration (Fig. 5.13). However, ©

at a low surface tension of about 32 mN/m (close to the

C.M.C.), the contact angle increased suddenly up to 170°,

except for sample 0-5. This abrupt increase in contact

angle is the same trend observed in the system of cationic

surfactant at surface tension of 38.5 mN/m. This phenomena

may be also explained by the adsorption of nonionic surfac-

tant on the surface of the solid, creating a barrier to

prevent the contact of the octane drop with the solid.

5-4. With Gum Arabic Solution

The same type of experiments were carried out for

the gum arabic solutions.

In octane medium, the contact angle of the gum arabic

-69-

Q>

CD

180

160

140

120

100 <.

"o 80 CO

»»!■/

£= o O 60

40

20

0

Non-Image

SJ-

30-5

30 40 50 60 70 Y"L of Nonionic Surfactant Solution

( mN/m )

Fig. 5.13 Contact angle of Octane in nonionic surfactant solution ( Triton X-100 )

-70-

solution remained constant as the concentration increased,

even though the gum arabic has a slight surface activity

(Fig. 5.14). Therefore, gum arabic has nothing to do with

spreading of the fountain solution on solids in octane

medium.

The contact angles of octane on solids in the gum

arabic solution were measured (Fig. 5.15). The octane drop

was released one minute and five minutes after the solid

was immersed in the gum arabic solution. Almost the same

trend as in the case of the commercial founta'in solution

was observed. However, with this gum arabic solution, even

for the lightly photo-oxidized polystyrene film, sample

30-5, the contact angle increased with increasing gum arabic

concentration, which indicates this solution is more active

than the commercial fountain solution. One reason for this

may be due to the pH [45], which was adjusted by phosphoric

acid. Almost all metal ions of gum arabic are dissociated

at low pH, and the H form of the gum arabic molecule

easily adsorbs, even on solids which are highly hydro-

phobic. Studies of contact angle measurements [46,47] or

adsorption studies of powders [48-51] on the non-image

areas have been reported. The adsorption of gum arabic

is effective for anti-scumming.

-71-

CD

0 0.2 1.0 Concentration of Gum Arabic Solution ( Wt%)

2.0

Fig.5.14 Contact angle of gum arabic solution on solids in Octane

-72-

o oo

CD NO

CD CD

CD CO

CD vO

CD CD CVJ

ITS

TO c CO

to

cz o

o in

.— !Q CO 1_ co

E ZJ en

to ■o

&

<X>

CO

O 52 «•_ to o l_

CD -°> E cf.§ CO

to

o -2 _2 =3

o — Q E

•—i

0 8|BUV PSJUOO

-73-

6. DISCUSSION

6-1. Spreading Coefficient

The interaction energies between solids and liquids,

as well as between liquids and liquids, have been studied

so far. However, when the conditions of the lithographic

printing process are considered, the adsorption theory of

bonding and debonding is important. The spreading coef-

ficient may be used to explain the phenomena of bonding

and debonding.

The spreading coefficients for phases 1, 2, and 3,

respectively, are described by balances of interfacial

tensions as follows:

51 = Y23 " -Y12 " Yi3 . (6*r)

52 = ^13 - ^23 " ^12 (6'2)

* S3 = Y13 " Y13 - Y23 (6*3)

Phases 1, 2, and 3 are defined as the ink, fountain solu-

tion, and plate, respectively.

6-1-1. Original Method

(A) Spreading Coefficient S2

The spreading coefficient S2 is defined in Equation

(6.2), and each interfacial tension can be written as

-74-

-.' vV*-*^-.

follows

Y12 = Yl + Y2 " 2/¥^ " J12 (6-4)

Y23 = Y2 + Y3 ~ 2v^2Yf " I23 (6.5)

Y13 = Yl + Y3 " 2y^M " 13 (6'6)

Therefore, the spreading coefficient for the fountain solu-

tion, S„, can be written as follows:

S2 Y13 Y23 ~ Y12 (6.7)

TT Q " Ypc c " YT TPC (6-8) I.S 'FS.S 'I.FS

/d d :/Y- YI + Ys " 2/YIYS - II>S - YFS " YS

+ 2/YFS

YS

+ ^.FS " YI " YFS v y%

+ 2^TY~c + IT ^ (6.9) d d 'lYFS " Î.FS

2/YFSYS + 2/YIYFS ~ 2*Vs " 2YFS

" V.S + ^S.FS + Î.FS (6'10)

However, when octane is used as the ink, the non-dispersion

interaction energies, I_ _„ and I , become zero since

octane has only a dispersion component. Therefore,

-75-

_ /a d" _,_ 0 /d~d ■ /d~~d S2 = 2*FSYS + 2/VFS " 2/Vs " 2YFS

+ ^.FS (6'11)

Since Yps = 21.8 mN/m, YQ = YQ = 21.8 mN/m,

S2 = 2^1.8xYg + 2/21.8x21.8 - 2/£l.8xYg

- 2YFS + ^.FS (6'12)

= 43.6 - 2YFS + ls>ps (6.13)

Therefore, the value of S~ is independent of the value of

Yd

The values of S2 calculated by making use of Equation

(6.13) are tabulated in Table 6.1. For the calculation,

the values of I_ _„ obtained from the contact angle measure- b.rb

menb of the fountain solution in octane medium were used.

These values are plotted in Figure 6.1. The values of S,

for the Non-Image Area were larger than any of the other

spreading coefficients, varying from -7.8\mJ/m to -0.1 V_.

mJ/m . The value of S2 approached zero as the surface

tension of the fountain solution decreased, indicating that

the fountain solutions tend to spread on the Non-Image

Area. However, since the value of S, for the Non-Image

Area does not become positive, the spontaneous separation

of octane from Non-Image Area by the fountain solution

does not take place.

-76-

CN to

-p

o -H O

-■H «R «W

CD o u CP c -K tJ 0) n ft

CO

rH

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CD t-« .Q rd EH

o in o

CN

rH

O 1

co CN

l

rH CN

1

o

en rH

1

en

4 VO

00 1

en

l

o C\J

CN

oo CN

1

CN

O 1

o rH CO

en CN 1

in

VD CN

1

CN

00 rH

1

CO

CO rH

1

en

rH

00

IT)

in co l

CO

o

o

CO 1

CO

CN

CO CO 1

CN

CN CN

1

CO

CO rH

1

O

H 1

CM

o

m m i

en

o 1

in

en in I

VO in

I

o CN in

VO

00 CO

1

en

CN 1

m rH

1

lO

o

CM

CO VD 1

CN

CN 1

CO

o r- I

00

VD vo 1

r-

CN VD

1 CO 1

H

CN CN

1

CN

CO rH 1

t-\ O >

CN • O

in

CO

1

CN

1

CO

VQ 00

1

00

l

VO

vo

in

CO

!

en

CO CN

1-.

CO rH

1

to <D •P

&

H

CN 00

«

00

r- l

CO

VO en 1

CO

o en

l

r-

rH in

I

CO

VO CN

1

in

o CN

l

-'-■

d)

rd e H

0)

fd e H 1 a 0

CO 1 o

CO

o CO

co 1 o m

CO

o o rH

CO 1 o in rH

CO 1 o o CN

CN

s

•P •H C D

-77-

cz o

o

cz CO

cz o

cz a)

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CZ o o

ro CO CO

CVJ CO

"c

o

o o an cz ■c ro cu »_

vO

juaiDijiaoo 6uipe9Jds

-78-

On the other hand, the value of S2 for non-photo-

oxidized polystyrene film, sample 0-3, was smaller than 2

any other spreading coefficients, varying from -96.3 mJ/m

2 to -23.7 mJ/m as the surface tension of the fountain solu-

tion decreased. The value of S2 of sample 0-3 was quite

small compared with that of Non-Image Area, indicating

that the fountain solutions have the least tendency to

spread on the polystyrene film.

The values of S2 for other solids were intermediate

between those"of two solids, the Non-Image Area and sample

0-3, showing the same trend that the value of S2 increases

as the surface tension of the fountain solution decreases.

(B) Spreading Coefficient S^

The spreading coefficient of octane on solids in the

fountain solution media, S, , can be expressed as follows:

Sl = Y23 " Y12 - Y13 (6'14)

= YS.FS - YO.FS " V.S (6-15)

+ 2/^ - T YS YFS ^S^S S.FS Y0 YSF

^&&$&yZU±Z'«*&&i£-i

dd 0TFS T0 TS ' "rT0YS (6.16)

= 2%YF"s + 2^t " 2VYSY>S " 2YO " ^.FS (6-17)

By substituting for v , y__ and yrt the values of 21.8,. 21.8

-79-

and' 21.8 raJ/m2, respectively, S1 can be expressed in a

simple form as follows:

S± = 2/21.8x21,8 + 2/21.8><Yg - 2/21.8*Y^

- 21.8x2 " ISFS (6.18)

" " ^.PS (6-19>

The calculated values of S, are tabulated in Table 6.2.

From Equation (6.19), it is obvious that the spread-

ing coefficient S,, never become positive. If the solid

has only the dispersion component, S, will be zero. How-

ever, since this is a special case, the values of S. for

common solids are usually negative.

Figure 612 shows the spreading coefficient S, as a i ■ \\

function of the surface-tension of the fountain solution.

Contrary to the case of S0, Sn for sample 0-3 was larger

than any of the other spreading coefficient, varying from

-8.4 mJ/m to -0.7 mJ/m2, and S1 for the Non-Image Area is

2 the smallest among them, varying from -100.8 mJ/m to -24.8

mJ/m2, which indicates that octane tends to spread on the

solid, sample 0-3, but not on the Non-Image Area in the

fountain solution.

However, surprisingly, the value of S, for Image Area

is rather small. Sinqe this Image Area is a commercial

2 product, the value of- S,, -55 mJ/m at Y _ = 72.3, is

assumed to be hydrophobic enough to repel fountain solution

-80-

co

•p

0) •H O •H m <4H <D o o tn

•H

<u n

CO

CM

vo

d) rH

o in

o CO rH CM

o

vo

rH rH

o 00 rH

CO

co CM

r-

co CM

rH

CM

o (N

(X)

in

CO

CM CO

CM

rH co rH

O

CM CM

rH

O CO

in

o co

rH

rH CO

00 CM CM

rH

00

rH

co

rH CM

00

00 co

o

CO

O

CM in co

co

CM VO

CM

CM VD CM

in

rH

in o vo

CM

O VO

in • o

vo

CO

CO

CO in CM CO

o 00 vo

vo

o

vo in vo

tfp

rH 0 > CM

•

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CM

a\ CO

1 1

00

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1

in

00 in l

vo

l

00

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l

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00

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r-

rH

1

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00

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vo

ON 00 1

C7> (d e H

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CO 1 o

CO 1 o CO

CO 1 o in

CO

o o rH

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co 1 o o CM

CM

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D

-81-

oo

o

o m

C~) CO.

vO co

to CD 1_ ir\

—*--. O

CD E O

^J- ^"s. -«_* 2: <J

E c:

-— 03 CD • m xn CO

CD

V 1*—

CD CO CXI 0

CD O O

CD cn c:

I—i "■0

CO co l_ 0. to

CD

CSJ

juapijjeoo 6uipB94ds On

82-

"#v

and accept ink. If this value is a standard that the

solid can be wetted by the liquid in a practical sense,

samples 100-3, 150-3, and 200-3 may be used as the non-image

area since their S» values are -51.7, -26.3,. and -20.5 mJ/m^,

respectively.

6-1-2. Kaelble Method

Kaelble introduced a fracture criterion [52] for the

spreading coefficient. A recent extension of Griffith's

theory of fracture incorporates the adsorption^theory state-

ments. The modified Griffith relation for failure by crack

opening under plane normal stress is expressed as follows:

..-/

2EY

where

a = the critical crack propagation stress

G = the length of the crack

E = Young's"modulus

y-„ = Griffith's surface energy for fracture

S0 is the spreading coefficient of phase 2 and can be re-

lated to Griffith's surface energy for fracture:

S2 vG - - -r <6-21'

-83-

Y

R .1

R

G

2 o

2

H

K

T,2 „2 R ri R o

0.25[(ai-a3)2 + (31-&3)

2]

(a2~H)2 + (32-K)2

0.5(ai+a3)

0.5(3^33)

(6.23)

(6.24)

(6.25)

(6.26)

(6.27)

where the phases are defined as phase 1 = ink, phase 3 =

plate, and phase 2 = fountain solution.

The condition Y„ <0 ideally prevails in the non-image

areas, where the dampening solution should debond ink from

the plate, whereas the condition Yr > 0 is required corre-

spondingly in the image areas.

By following the Kaelble method, the values of «3 and

3_ for the Image Area and Non-Image Area were calculated

and are tabulated in Table 6.3.

Table 6.3. Square root of dispersion component and polar component for *Image Area and

Non-Image Area.

Non-Image Area

a.

3-

7,09

5,47

Unit: mJ/m

These values were calculated using the,contact angle of

water on solids in air. Since the octane is a model for /

-84-

J3

the ink, otl = 4.67 (y . =21.8) and 3, = 0. For the i octane l

fountain solution, a. = 4.67 (Ypq = 21.8) and $_ varies from

7.11 (Y£L =50.5 for water) to 3.52 (Y£0 = 12.4 for 50 vol %

FS) .

Figure 6.3 shows Griffith's surface energy for fracture,

and the graphical determination of the.range for the surface

properties of the fountain solution.

For Image Area, since the solid line of the fountain

solution does not intersect the circle, the octane on the

Image Area will never be separated by the fountain solution.

For the Non-Image Area, the solid line crosses the circle,

indicating that, when the surface tension of the fountain

solution is lower than 52.2 mN/m, the octane on the Non-

Image Area can be replaced by the fountain solution

spontaneously. However, in fact, the spreading coefficient,

S^, never becomes positive, and experimentally the octane

on the Non-Image Area is never replaced by the fountain

solution, as described, in Chapter 6-1-1, unless the surface

tension of the fountain solution is lower than 32 mN/m,

Therefore, the Kaelble method does not adequately explain

the experimental results.

The comparison between the values of I„ ps obtained

experimentally and those calculated using the Kaelble

theory was made. To define Yq for the Kaelb/le method, the

experimental data of the non-dispersion interaction energyt

-85-

o

CO

CD cn co

i C o

- vO

\

is)

LLI CD

""' _J"

CD c y co / o / * O /

- «NT

oo vO

( IU/NUI ) £70

0°^

CO

CD Cn CO CD

cn CO

to ^

00

f( UI/NUJ ) *?o

- CNi

CNJ

00

—,M

O]

QQ.

00

vO

CNJ

OO

CD O cz CO i_ CD -—-

o -o ■*-' o

CD -*= JZ CD

■~ E O o

.2 CD lt_> CO

CO s^* c

CD u"_

-w o .CD '-

To o

^ cz

■C O cz *— fO CD

^ JZ CD "*"^

CO CD

«*— o >^ O. cn 1— CD CD C_> CZ ro CD j_ CD Z3

CO

t: «> t/5

2=1 CD v.— cn :t= cz i_ CO

CO

cn

-86-

of water with solids in octane medium were used, For the

Image Area, since the non-^dispersion interaction energy,

Isw = 18.9 mJ/m , Y~ can be calculated as follows:

TSW = 2^¥l : (6-28)

18.9 = 2/^*50.5 * (6.29)

yP = 1.77 mJ/m2 (6.30)

Similarly,& for other fountain solutions I0 TT can be calcu~ b « W

lated by using Equation (6,28) , These valued are tabulated

in Table 6.4. The same procedure was used for Non-Image

Area. The calculated value of Y? was 43,0 mJ/m . The re- >

suits are tabulated in Table 6,5, comparing the experimental

results with those calculated using Kaelble!s method.

From these comparisons, it is clear that the I0 „_ b.rb

obtained by Kaelble method is overestimated, especially for

high concentration of the fountain solution. Therefore,

Kaelble method gives results as if the octane on the Non-n

Image Area were replaced by the fountain solution spontane-*

ously, whereas the spreading coefficient, S2r never becomes

positive, as shown in Chapter 6-^1-1,

Since there are no standard values of the spreading

coefficients S, and S2, which define the tolerance range

for the surface properties of the fountain solution, the

determination of the values of the spreading coefficients

may not be so useful for the surface energetics analysis

-87-

•a — en **. "N . r- CM N CD rd o • • g (U'o o • • g C <D iO ro en ^ ô in ^ VD **^

•H U •O +»X5 CN ^ rO rd < 6 ^ .a a)

g •P ,Q a) -p g • • o o> CN r> -P -H CN 00 ■P

rd o • • •H £ (D o • * • •H

DJH (N •<* o C rH CM CN CN C

rH P rd,Q CO in D (I) rH

• ll /It vu ^ rd

a) • en CN « ir» o T3 00 • • <u 00 • •

G o VO CM Cnnd rH o o .c rH rd C •^ vo

•H -p g fd -p (1) o g

k-l

i +> rd ■*r (T) a c * m CO U 0) CN • • O <D CN • • a) IH r^ •«# s g rH CO -P,Q rH •H VO r^ C rH

0 <D -H Q) rd ft c « IT) CN rH in CN in

o • • • • • • -H TJ O o VO ^ o rH a» W G rH rH <D g r> r- ^ rd C O V O cu u d, (Q to +J C»P c dp

•H rH cd »tf 3 rH •H CD rH

1 w O en 00 •P C 0 CN r- C Q) > • • O -H > • • O V4 in f^ rd rd in r^ C CM rH rH U -P CN 00 00

rH • CD,Q • a) rd O •P 0 O ^ -p

•H CO -P c Q) u en en d u CN CN

«H g o • • C O (0 • • O -H -p CO 00 O-H ■p co CO

S-l rd rH rH -H -P rd CT» en c a) IS CQ 3 & o ft MH

Q) 0 w X •H 0 •O ft CO -0 u O W 0 rd g A ■H C Si ft o -P TJ -H •P 6 u •P a) 1 rd ■P Q) o *U C g C -P C g u a) O C <D

g a) S 3 g (1) \ •H rH 0 •H rH

• r-4 .Q *H J-» A ■** <D H • 0) rH

• &

0) in ft Q) vo rd • X rd

w W vo w « 0)

rH g g a) g g .Q o o rH o O rd M u .Q u H EH iw

CO fa

CO 1 H

CO fa

CO 1 H

rd EH •

CO fa

CO H

CO fa

CO H

-88-

of lithography.

6-2. Work of Adhesion

Since the spreading coefficient gives only an indica-

tion whether a solid £s suitable for an image area or a non-

image area, another energetic, interaction term should be

considered to clarify the mechanism of lithographic printing.

The-work of adhesion may be one of the terms which control

the printing mechanism. The printing process can be divided

into two parts, the initial inking process and during

printing.

6-2-1. Initial Inking Process

A printing plate must be inked before printing. This

initial step is called the inking process. In practice, this

process is not so important. However, if an image area is

not hydrophobic enough, it would take time to build up a

reasonable ink film thickness on the image area or the image

area cannot have a reasonable ink film thickness with the

normal feeding of ink and fountain solution. If a non-image

area is not hydrophilic enough, the ink will deposit on the

non-image area with normal feeding of fountain solution.

For image areas, W (image-ink) > W (image«rFS) , and A A

for non-image areas, W (non-image-FS) > W_ (non-image-ink)

are required to build up a sufficient ink film thickness on

the image area without tinting or scumming.

To calculate the work of adhesion, the Kaelble theory

was used since the equations for this system have not been

-89-

developed. However, since the off-^set printing ink is

composed of mainly the dispersion component, the calculated

error would be small. From Kaelble's equation, the work

of adhesion is described as follows:

WA " 2/K + 2^ (6-31)

For the system: ink = octane; plate = sample 0-2; and

FS = water, the work of adhesion of octane on sample 0-2 is:

W = 2/48x21.8 = 64,9'mJ/m2 (6.32)

The work of adhesion of water on sample 0-2 is:

W = 72.3 (1 + cos 86,4) = 76,8 mJ/m2 (6,33)

Similarly, for the system: ink = ink; plate = sample 0-2;

and FS-= water, the work of adhesion of ink on sample 0-2

is:

r W_ = 2/48x29.7 + 2/0,02x0.50 = 75.7 mJ/m2

« • -i

where

YInk = 29'7' YLk - °-02

*0-2 " 48-°' TfP_2 - 0.50

The work of adhesion of water-^3n sample 0-2 is calculated if

from the contact angle of water on it in air. These works

of adhesion of the hydrophobic solids as well as the hydro-

philic solids with octane, ink, or the fountain solutions

are calculated and tabulated in Table 6.6, The following

-90-

Xi • +> M

C 13 -H C rd T3

C W tO

T3 -H 01 ^T3 O -H W rH

O CD W

+i CD .a

c -P o <D 5 o ■p CD CO

P G -H O +> -H 3 W rH CD O Si W

cd C -H

«w id o +> c CO 3

o o

"vo

. cu iH .Q «d EH

rH o\ r» in <jp • • • » o ^r f\ •«* Cr» in vo vo o

rH VO

<*> o\ o CM m o • • • * CM r* rr O in

vo vo t-i rH

vo

V* .

CO rH CM rH • • • •»

OP 00 in in - VO 00

vo vo r-i vo t-i^

rH 00 m ^ • » • 1

CM 00 H r- rH VO r> CM CO

t-t

dP vo CTl ' in O • • • • *

in o CM CM r-<- o r» CO

r-i cri

_« ^

dP in in CM ** • * 1 [

• n rH 1 I O r-~ 00

u CO in a\ 00 o » •> • •» +J vo o en CM rd r- 00 ^ rH &

* rH rH

^

H

• in

CM

o

00 •

00

CT> •

t^- r* r^- r~

CD C cn 00 CM vo itf m • • »

■P .■^f o\ vo CM O vo in vo vo O

d) ,CP . fd

CD g CN tn H CM

1 cd„ 1 1 • o e c O

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CM

r3 g

•P •H C D

-91-

values were used for these calculations.

Y^ = 50 3 Y'P = 29 9 Non-Image " ' Non-Image

Y100-2 = 45'° ' Yl00-2 = 8a tUnit- roj/m2! >

From the results, since the work of adhesion of octane with

the Image Area is smaller than those with the fountain

solutions, octane is not suitable as an ink for this system.

On the other hand, the work of adhesion of ink with Image

Area is larger than those of the fountain solutions in con-'

centrations greater than 2 vol %. Therefore, to.lower the

surface tension of the fountain solution is preferable for

the initial inking process unless there is emulsification of

ink by the fountain solution. As for hydrophilic solids

such as the Non-Image Area or sample 100-2, the values of the

work of adhesion with octane and ink are calculated in the

absence of the fountain solutions. This is not a practical

case. » In the case of inking process, the fountain solution

wets the non-image areas before inking, so the direct inter*,

action of ink with the non-image areas can be prevented.

However/^1^|^îsJûld. Jhe, recognized that the work of adhesion

of the Non-Image Area with ink is quite large in the absence,

of water. To increase the surface tension of fountain solu-

tion is preferable for the adhesion of fountain solution on

non-image area,, whereas to lower the surface tension is

preferable for the work of adhesion of ink on image area,

- <-92-

6-6-2. During Printing '''■■*

Once the inking is completed, another interaction force

will take over the mechanism of printing. Since the image

area and the non-image area are covered with ink and foun-

tain solution, respectively, the fountain solution inter-

acts with ink on the image area and the ink interacts with

the fountain solution on the non-image area, and do not

interact with image area or non-image area directly any more.

Since it was found that octane cannot be used as an

ink in Chapter 6-2-1, only commercial ink is taken into con-

sideration, in this chapter. For an image area such as sample

0-2 or the Image Area, the work of adhesion of the ink is

equal to the work of cohesion of ink since it is provided

that the image area is covered with ink. Therefore, the

work of cohesion of ink is

W = W s 60 mJ/m2

On the other hand, the work of adhesion of water on ink is

as follows from the experiment:

W = 72.3 (1 + cos 105) =53,6 mJ/m2

This value is smaller than that of the ink, which indicates

that the ink adheres to ink, whereas water is repelled from

the ink film. The works of adhesion of the fountain solu-

tions were calculated from the contact angle measurements

on the dry ink film in air, and tabulated in Table 6,7.

-93-

Table 6,7, Works of adhesion of ink and ink or the fountain solutions.

..... ._

Ink

Ink Water 0.2 0.5 2 8 *2Q 50

60 rrtr

53.6 54.9 52.1 51.5 57.8 56.5 57.7

Unit: mJ/m''

The relation, W (Ink-Ink) > W (FS-Ink), is valid with any

concentration of fountain solution. However*, there seems to

be an optimum point in the range of 0.5 to 2 vol %.

For the non-image areas, the relation W (FS-FS) > '

W (ink-FS)/ should be satisfied. The calculated values are

tabulated in Table 6.8. ' <

Table 6.8. Works of adhesion of the fountain solution ' and fountain solution or ink.

Water 0.2 0.5 2 8 20 50

FS-FS 144.6 13.3 117 106 85.4 76 68.4

Ink-FS 53.6 54,9 52,1 51,5 57 f 8 56.5 57.7

Unit: mJ/m

From the values of works of adhesion in Table 6.8, even

though there is a trend that the higher surface tension of

fountain solution is preferable, any concentration of foun-

tain solution can be used as long as the fountain solution

covers the non-image area. Therefore, for the non-image

areas to be always wet with fountain solution is an

_: -94-

important requirement, Since the works of adhesion of the

ink and the fountain solutions are smaller than the works

of cohesion of the ink as well as the cohesion of the

fountain solution, splitting occurs between the ink film

and the fountain solution. However, as the surface ten-

sion decreases, part of the fountain solution can be taken

away by ink.

This discussion on the work of adhesion shows that the

more hydrophobic the image.area and the more hydrophilic

the non-image area, the wider the effective range of the

fountain solution concentration when the commercial ink is

used for this system.

6-3. Work of Adhesion in Octane or in the Fountain Solutions

In Chapter 6-2, the work of adhesion of solids with

liquids in air was discussed, However, in any conditions,

the work of adhesion of the image arears should satisfy

W (image-ink) > W (image-FS) and, at the same time, A A.

W (non-image-ink) < WA (non-image-FS) for the nonîmage

areas. For-example, in the fountain solution media, the

fountain solution on the fton-Image Area must not be re-

placed by octane, whereas the fountain solution on the

Image Area must be replaced by octane. In Table 6.9, the

values of W of solids with octane JLn the presence of

water, 2% fountain solution and 8% fountain solution are

-95-

tabulated. To lower the surface tension of the fountain

solution is preferable for the non-image area because the

work of adhesion of these solids with octane becomes smaller.

On the other hand, to.lower the surface tension of the

fountain solution is not preferable for an image area such

as sample 0-3 and the Image Area since,the interaction

energy between these hydrophobic image areas and octane

decreases rather abruptly.

Table 6.9. Works of adhesion of solids with octane in the fountain solution media.

Octane drop Water 2% FS 8% FS

0-3 91.9 59.2 40.0

Image 47.0 27.4 19.1

200-3 r 7.7 1.2 . 0.5

Non-Image 0.2 0.1 0.08

Unit: mJ/m

Unfortunately, the same calculation for the commercial off-

set ink cannot be carried out because it is impossible to

carry out the experiment for the system of real dnk^^r-

For the plate immersed in octane medium, a plate for

the image area must have a stronger interaction with octane,

On the other hand, a plate for the non-image area must not

have an interaction with octane. In Table 6.10 the works

of adhesion of plates with the fountain solution in octane

-96-

medium are summarized. ^

Table 6.10. Works of adhesion of solids with the fountain solutions in octane medium.

FS drop Water 2% FS 8% FS

0-3 4.7 2.5 1.8

Image 19.4 8.4 .5.4

200-3 84.3 47.3 26.7 .

Non-Image 93.3 61.5 41.5

Unit: 2 mJ/m

The reverse trend compared with the system in fountain

solution media can be seen for both the image areas and

the non-image areas. To reduce ""the surface tension of the

fountain solution is preferable- for the image area, where-

as to reduce the surface tension is not preferable for the

non-image area in this system. Therefore, there must be

a compromise in terms of the surface tension of the fountain

solution.

As the result that octane cannot be used as an ink

has been discussed in Chapter 6-2, further discussion is

not needed. However, the same trend can be expected when

a commercial ink is used for this experiment instead of

octane.

-97-

6-4. Tinting and Scumming

In this chapter, practical problems such as tinting

and scumming are related to the experimental results and

an explanation for these problems will be given.

From the experimental results, as long as there is

water on the non-image area, scumming will not take place,

since the work of adhesion of oil (octane) on the non-image

area in fountain solution is quite small. Wilkinson et al.

[53-57] proposed that scumming and tinting are regulated

by water leavel, w,hich affects the area of the image and

non-image part on the print, from the study on the spreads,

ing and wetting phenomena- in four-phase configurations.

However, because of the other factors such as blinding,

water mark, emulsification of ink, and picking, a large

amount of water canot be fed to the plate. A reasonable

feed of water should be taken into consideration. There-

fore, the first requirement is that the fountain solution

should wet non-image areas with normal feeding. This re-

quirement can be attained by means of lowering the surface

tension of fountain solution to a certain- extent. The rer>

quired value of the surface tension of fountain solution

varies according to the hydrophilicity of the non-image

area-. When the hydrophilicity of the nonîmage area is

low, the lower surface tension of the fountain solution

should be required. However, some other unfavorable

phenomena would be involved in this system such as

-98-

"~A

?4

enhancement of ink emuls;if i,cationf blindingf and tinting.

Blinding can be easily understood as the result of the

spreading coefficient of the fountain solution on the Image

Area, S2, increasing to the value which is close to the

value for the Non-Image Area as the surface tension of

fountain solution decreases. Thereforef some compromise

must be made to satisfy all these factors/

Besides these factors, the mechanical movement of

the off-set press should be considered. The plate normally

passes through four inking rollers, one after another.

Therefore, even though there is enough water on the nonr*

image areas, these inking rollers squeeze out the water

On the non-image areas as well as some water on the ink

film on image areas, Therefore, the print density does

not change too much within the tolerance limits of the

ink-water balance [58] , And the ink would adhere to the

non-image areas unless there is tightly adsorbed water on

the non-image areas. In this sense, the adsorbed gum

arabic has an important role to avoid scumming, even though

the scumming tendency of modern anodized plates is very

low, for both mechanical and chemical reasons [59] , go,

if the non-imaê areas are not hydrophilic enough to hold

a minimum amount of water, the non^-image areas will be

adhered to by ink with the normal feed of fountain solution,

Banks et al, [60] proposed the mechanism of scumming

as follows. Ink components may shed films onto non-ima,ge

-99-

areas covered with water/t Scumming takes place on rerunning

after stoppage of the press. They show that a practical

way of avoiding this type of scumming is to use nonionic

surfactants or very low volatile alcohols such as 2-ethyl-

1,3-hexanediol in the fountain solutions. However, at

concentrations as high as 2,5% of this alcohol, there was

occasional evidence that ink transfer was reduced to such

levels as to give "weak" prints, Zettlemoyer et al. [61^

63] also studied the adsorption of hydrophobic substance

such as octanoic acid on aluminum plates. Bock 164] point-*

ed out some unique features of alcohols, such as rapid

wetting ability, volatility, lubricant and nonêmulsifying

roles—which explain why tinting does not occur with alco-

hols, although there is a problem of tinting with nonionic

surfactants of low volatility (the surface tension of the

tested solution with nonionic surfactant was 16-27 mN/m).

On the other hand, Alexander [65] states that (1) a foun-

tain solution should have a high surface tension on the

plate, and (2) that a low surface tension is advantageous

only in the dampening system. The results/of this work

lead to the same conclusion as Alexander's, as described

in Chapter 6-2, i.e., the cohesion of water is the largest

value among dampening solutions and much larger than the

work of adhesion of ink and dampening water. However,

this conclusion is correct only if the water can wet the

surface of the non-image areas with the normal feeding.

-100-

As for tinting, several reasons—many of them almost

opposite—have been suggested for it,

1. Excessive emulsification of water in ink

[2,64,66] or ink in water [49,64,66,67],

2. Insufficient water feed [53,64,66,68] and

even excessive water feed [53] and, naturally,

excessive ink feed,

3. Excessive [5] and insufficient [68] surface

tension of the water and interfacial tension

[2,66] between the water and ink. i

It has also been postulated that tinting is the lower limit

of water feed tolerance [68f69].

However, considering all these reasons and our experi-

mental results, a clear picture for the mechanism of scum-?-,

ming and tinting can be obtained. Nonionic surfactant is

effective for preventing scumming in such a way that the

nonionic surfactant can emulsify the oil film transfered

from the ink into the fountain solution, so that the eimilsi*

' fied oil film can be easily removed from the non^-image area

by the dampening water on rerunning, even though the pla.te

is dried due to stoppage. Too much nonionic surfactant

can emulsify even the ink itself, causing tinting or a

weak image [70,71]. Volatile alcohols such as isopropyl i

alcohol are effective for lowering the surface tension

of the dampening solution without emulsifying the ink.

^101-

This helps wet the non-image areas completely, so that ad-

hesion of ink on the non-image areas can be avoided.

Therefore, a nonionic surfactant should be included

in the dampening water to a sufficient extent to emulsify

the oil film from the ink.' Alcohols can be added to this'

dampening water to lower the surface tension to the level

at which the dampening water can spread on the non-image

areas. However, there are two factors which limit this

value of the surface tension. One is that the gum arabic

should not be precipitated owing to the presence of alco-

hols [72], since gum arabic cannot be dissolved by alcohols.

The other factor is that the dampening water should not wet

the ink film on the image areas, since the inking process

may be hindered and give a weak imaget The contact angle

of the dampening water on the ink film should not be less

than 45-50°'.' According to the experimental- results of the .

dry ink film (Fig, 5.3), the surface tension of the dampen-

ing water should not be lower than 34 mN/m for this ink.

Therefore, the surface tension may be adjusted by nonionic

surfactant and isopropylalcohol. The amount of nonionic

surfactant depends on the composition of the ink used.

*102-

7. CONCLUSIONS

Several experiments have been carried out to determine

the mechanism of lithographic printing. The following find-

ings were obtained from these experiments,

1. The non-dispersion interaction energy of

photo-oxidized polystyrene film increases

greatly, whereas the dispersion component

decreases only a little as the exposure time*

increases. r

2. The non-dispersion interaction energy of

water and solid measured in octane has al*-

most the same value as that in air, whereas

the non-cjispersion interaction energy mea-

sured in water by octane has higher values.

The difference between those measured in air

or in octane, and those measured in water,

comes from measuring the advancing contact

angles of water or receding contact angles of

water, respectively. However, the differ-

ence of non-dispersion interaction values

measured in air and in octane medium may

be explained by the film pressure effect,

TT . The non-dispersion interaction energy

of a solid measured in water media is more

-103-

sensitive to the degree of hydrophilicity

of the solid.

3. The dispersion component of the Non-Image

Area of a Kodak Polymatic lithographic plate

was 50.3 mJ/m by methylene iodide. This

value seems small compared with the dis-

persion component of other metal oxides

determined from gas adsorption. However, by

measuring the contact angle of methylene

iodide and a-bromonaphthalene on the Nonr*

Image Area in water, its dispersion energy

was 47,0 mJ/m and the nonr-dispersion inter-

action energy with water was 109,0 mJ/m2.

4. Cationic surfactants cannot be used as

one of the ingredients of a fountain solu.ry

tion since the adsorption of a cationic sur-

factant on surfaces makes them hydrophobic.

This was demonstrated by measuring the contact

angle of the cationic surfactant solution on

solids in octane,

5. Nonionic surfactants can be used in a foun-

tain solution as-one of the ingredients.

However, the surface tension of the solution

should not be lower than a critical value at

which emulsification of ink may be severe

and cause tinting,

-104-

6. Gum arabic adsorption on the non-dmage areas

at low pH can help repel ink adsorption on

the non-image areas. One to two percent

gum arabic solution may be needed for this

purpose.

7. The spreading coefficients S, and S^ never

become positive. These values do not give

a solution for the mechanism of lithographic

printing, According to the Kaelble method,

at certain concentrations of the fountain

solution, octane should be repelled from

the Non-Image Area by the fountain solution

spontaneously. However, experimentally,

the split did not take place with any con^

centration of the fountain solution; in<-

stead, it gave a finite contact angle. It

. was found that the non-dispersion inter-

action energy was overestimated by' using

the Kaelble method.

2--c.v:'maffl printing process can be divided into

an initial printing and a during printing

stage. For the initial printing process,

W (image-ink) > W (image-FS) should be

satisfied for image areas; otherwise, it

will take too long a time for the image

areas to build up an ink film of sufficient

-105-

thickness^ or the ink film may be very thin.

After the initial inking process, W (ink"

ink) > W (ink-FS) for the image areas, and

W (FS-FS) > WA (FS-ink) for the nonîmage

areas, should be satisfied provided that the

non-image areas are wetted by the fountain

solution. In general, once the image areas .

and non-image areas are covered with ink

and fountain solution, respectively, thiss

requirement will be satisfied,

9. The surface tension of the fountain solu-

tion should be chosen according to the

nature of the image* area and the non-image

area. The more hydrophobic the image area

and the more hydrophilic the non-image area,

the wider the latitude for the surface

tension of the fountain solution,

10, With consideration of the contact angle of

the diluted commercial fountain solution

on the ink film, the minimum surface tension

can be decided and adjusted by nonionic sur-

factants and isopropylalcohol (for this

system y = 34 mN/m), The amount of nonionic

surfactant required depends on the nature of

the ink used. The role of the nonionic

surfactant is to emulsify oil leached from the

-106-

ink, whereas the role of the isopropyl alco^

hoi is to spread on the non^-image areas

easily without emulsifying the ink. This

consideration may avoid tinting and scumming,

J\.

-107T

REFERENCES

1. Tollenaar, D., 12th IARIGAI Conference, Versailles 1973.

2. Schlapfer, K., 13th IARIGAI Conference, Wildhous 1975.

3. Padday, J. F., Printing Technology 1969, 13 (1), 23. » • ' ' ' ■■■■■I "i i ™ ■ i »i . i

4. Badescu, Th.; Papahagi, L., Bui. Inst. Politeh. Bucuresti, 1969, 31, 37.

5. Kaelble, D. H., Dynes, P. J., "Adhesion Science and Technology" Vol. 9B, Plenum Publ., New York, 1975.

6. Fowkes, F. M., Ind. Eng. Chem., 1964,* 56, 40.

7. Fowkes, F. M., "Fundamental Phenomena in the Materials Sciences" Vol. 2, Plenum Press, New York, 1966.

8. Girifalco, L. A.., Good, R. J., J. Phys. dhem., 1957, 61, 904.

9. Blanks, R. F, Prausnitz, J. M., Ind. Eng. Chem., 1964, 3, 1.

10. Gardon, J. L. , Paint Technol., 1966, 38, 43. 1 * ■ ?^. *

11. Meyer, E. F., Wagner, R. E., J. Phys. Chem., 1966, 70, 3162. .~

12. Meyer, E. F., Wagner, R, E.f ibid., 1971, 75, 642.

13. Goody, W., J. Chem. Phys., 1939, 7, 93.

14. Goody, W., ibid., 1949, 8, 170.

15. Goody, W., ibid., 1941, 9, 204.

16. Small, P. A., J. Appl. Chem,, 1953, 3_, 71,

17. Hansen, C. M., J. Paint Technol., 1967, 39^ 104f '505,

18. Drago, R. S., Vogel, G. C, and Needham, T. E,, J. Am. Chem. Soc., 1971, 93, 6014. ^

-108-

19. Fowkes, F. M,, AICHE Meeting, New York, 1977.

20. Tadros, M. E., Hu, P., and Adamson, A. W,, J. Colloid. Interface Sci., 1974, 49 (2), 184.

21. Hu, P., Adamson, A. W., ibid., 1977, 59 (3), 605.

22. Matijevic, E.f "Surface and Colloid Science Vol. 1", Wiley-Interscience, New York, 1969.

23. Andreas, J. M., Hauser, E. A., and Tucker, W. B., J. Phys. Chem., 1938, £2, 1001^

24. Zisman, W. A., Advan. Chem. Ser., 1964, 43, 1.

25. Ellison, A. H\ , Zisman, W. A., J. Phys. Chem., 1954, 58, 260.

26. Lee, L. H., "Adhesion Science and Technology Vol. 9B", Plenum Publ., New York, 1975.

27. Wu, S., CT. Phys. Chem., 1968, 72^ 3332.

28. Dann, J. R., J. Colloid. Interface Sci., 1970, 32 (2), 302., :

29. Dann, J. R., ibid., 1970, 32 (2), 321.

30. Tamai, K., Makuuchi, K., and Suzuki, M., J. Phys. Chem., 1967, 71 (13), 4176.

31. Tamai, K., Matsunaga, T., and Horiuchi, K., J. Colloid. Inteface Sci., 1977, 60 (1), 112. ' \t

32. Panzer, J., ibid., 1973, 44 (1), 142.

33. Wu, S., J. Adhesion, 1973, 5, 39.

34. El-Shimi, A., Goddard, E^y D; r3^^^^^^—- " ^rjjaterf ace Sci., 1974, 48 (2), 242.

35. El-Shimi, A., GOddard, E. D., ibid., ~1974, 43 (2), 249.

36. Good, W. R., ibid., 1973, 44_ (1), 63.

\ 37. Good, R. J., Koo, M. N., ibid., 1979, 71 (2), 283.

38. Sharpies, L. K., Plast. Polym., 1969, 37, 135.

39, Hiemenz, P. C, "Principles of Colloid and Surface Chemistry" Chapter 6.12, Marcel Dekker, New York, 1977.

-109-

«&

40. Severn/ I, D., Burring, S, L,{ "Wetting, Spreading, & Adhesion", Academic Press, London, 1978.

41. Fox, R. B., Price, T. R,, and Cain, D. S., Advan. Chem. Ser., 1968, 87_, 72.

42. Hamilton, W. C, J. Colloid. Interface Sci. , 1972, 40 (2), 219.

43. Bagnall, R. D., Green, G. F., ibid., 1979, 68 (2), 387. "7

44. Coupe, R., "Science of Printing Technology" p. 92, Cassell, 1966.

45. Beatner, G. C, Proceedings Technical Assn. of Graphic Arts, May 1951.

46. Adams, R. A. C., Int. Bull, for the printing and Allied Trades, 1956, NO. 73, 30.

47. Marton, J., Lipovac, S. N., Tappi, 1974, 57 (7), 86.

48. Bassett, D. R., M.S. Thesis, Lehigh University, 1963,

49. Schaeffer, W. D», Kuo, C. Y., Zettlemoyer, A. C, "Ad~ vances in Printing Science and Technology" p, 247, Pentech Press, London, 1962.

50. Labbauf, A., GATF Research Department Report of Progress, p. 225, 1970. .*.

51. Adams, R. A. C, Print, Tech. , 1971 ^'15 (2), 29.

52. Kaelble, D. H., J. Appli. Poly. Sci,, 1974, 18, 1869.

53. Wilkinson, M, C, Aronson, M. P,, Vanderhoff, J, W,, and Zettlemoyer, A. C, "Adhesion Science and Technology" Vol 9B, Plenum Publ., New York, 19751

54. Wilkinson, M, C, Zettlemoyer, A, CM AronsQnp ^t PT, and Vanderhoff, J. W., J. Colloid. Interface Sci., 1979, 68! (3) , 508.

55. Wilkinson, M. C, Ellis, R., Aronson, M. P., Vanderhoff, J. W., and Zettlemoyer, A. C, ibid., 1979, 6£ (3) 545.

56. Wilkinson, M. C, Mattison, I. C, Zettlemoyer, A, C.f Vanderhoff, J. W., and Aronson, M. P., ibid., 1979, 68 (3), 560.

•110-

57. Wilkinson, M, C, f Ardnson, M, P., Zettlemoyer, A. C, and Vanderhoff, J. W,, ibid., 1979, £8 (3), 575.

58. Lehtonem, T., Simomaa, K., 14th IARIGAI Conference, p. 21, Marbella, 1977.

59. Manninen, M., Virtanen, J,, Graphic Arts in Finland, 1975, 4, 9.

60. Banks, W. H., Charlesworth, D, H., Smith, A. H., 10th IARIGAI Conference, Vienna, 1969.

61. Lavelle, J. A,, Schaeffer, W, D., and Zettlemoyer, A. C, Taga, 1967, 127.

62. Lavelle, J. A., Schaeffer, W. D,, and Zettlemoyer, A. C, ibid. , 1967, 277.

63. Schaeffer, W. D., Bassett, D, R., Kuo, C, Y., and Zettlemoyer, A. C, ibid, , 1965, 17.

64. Bock, R. F., 10th IARIGAI Conference, Vienna, 1969.

65. Alexander, M., FOGRA-Forschungsbericht 5, 203, Munich, 1975.

66. Karttunen, S., Manninen, M., 14th IARIGAI Conference, Marbella, 1977.

67. Rostedt, C. 0., Madsen, E. S,, Print. Tech., 1966, 10, 18.

68. Decker, P., Thesis for dissertation, Technical University Munich, 1974/

69. Pyliotis, D., FOGRA Forshungs-Bericht 3.214, Munich ;L974, p. 39.

70. Lindqvist, U,, Graphic Arts in Finland, 1976, 5, 32.

71. Rostedt, C. O., Madsen, E, S., prin. Tech., 1966, 10, 18. "~~

72. Subt, S. S. Y., Praskievicz, R. W,, and Materazzi, A. R., Tappi, 1979, ST, 95.

-Ill-

VITA

Yonezo Kato was born on February 11, 1949,

in Saitama, Japan, the son of Hideo and Kiku Kato.

He attended Kasukabe High School in Saitama and

entered Chiba University in Chiba in April, 1967.

Yonezo graduated with a Master of Science degree

in Image Science and Engineering in March, 1973

and immediately afterwardte accepted a position

as a research chemist for Oji Paper CO., Ltd.

in Tokyo, Japan. While working for Oji Paper CO.,

Ltd. he was selected as a foreign student by his

company and entered the Graduate School at Lehigh

University in August, 1978.

-112-

Documents

Surface energetics of lithographic printing plate and