Thermal Printing Chemistry for Digital Outputdafoster/Papers... · Slip Layer/Heat Resistant Layer ... Neuman, “Titanium Alkoxide Subbing Layer Chemistry,” 10th International

©Eastman Kodak Company, 2005

Thermal Printing Chemistry for Digital Output

David G. FosterEastman Kodak Company

Rochester, NY 14650


Overview of Talk

• A Definition of Thermal Printing• System Review• Media Design

– Dye donor– Receiver

• Image Quality• Applications• Wrap-Up/Questions


Resistive-Head Thermal Dye Transfer Printing

A digital printing method where thermal energy is used to make photographic quality output by the transfer of dyes from a donor ribbon to a receiver that are in intimate contact.– Used for over a decade– Consumer, government, professional, entertainment, commercial,

and home printing– Historically used in low-volume but expanding quickly to high-

volume applications– Both single- and multiple-printhead printers


Some Applications for Thermal Printing

• Kiosk printing from digital cameras • Home printing of images• ID Cards, passport photos• Studio portraits• Diagnostic imaging• Entertainment imaging (i.e., images from theme park

rides)• Color proofing in publishing industry• And the list continues to grow…


The Thermal Printing System

Donor Ribbon

Printer

Image

Firmware&

SoftwareReceiver Sheet


Simple Model of a Thermal Printer

Donor Take-Up Spool

Printhead

Donor Supply Spool

Donor RibbonReceiver Sheet

U.S. Patent 4,621,271


Printing Process Steps

• Electronic image is subjected to color separation and converted into electronic signals

• Yellow, magenta, and cyan electronic signals are transmitted to a thermal printer

• Images are created by printing yellow, magenta, cyan, and over-laminate patches from the donor to a receiver

Yellow first Magenta second

Cyan third Laminate last


Major Attributes ofThermal Dye Transfer Printing

• Reflective prints and transparencies of multiple formats

• Color and black & white• Simple and reliable

equipment

• Dry process• Continuous tone scale• High resolution• Ecologically clean


Media Design


Donor Design Considerations

• Raw stock keeping• Energy to print• Printing artifacts• Interaction with

hardware• Coating

• Dye• Polymeric binder• Dye-to-binder ratio• Dye diffusion• Additives/addenda• Interaction with

receiver


Engraving Pattern

Gravure CoatingIn gravure coating, the rigid coating cylinders have cells, grooves, and patterns of a specific volume engraved into the surface. These cells are filled with fluid and the pattern of the engraving is transferred to the substrate surface.*

* “Liquid Film Coating,” edited by S.F. Kistler and P.M. Schweizer, Chapman & Hall, NY 1997, Chapter 12c.


Multi-Station Gravure Printing Press

SupportPath

Dryer

CoatingStation

Cyan Station Magenta Station Yellow Station


Thermal Donor Basic Structure

Dye Side Coating (~0.4 µm)

AdhesiveLayer

(~0.1 µm)PET

(4.5 and 6 µm thickness)

Slip Layer/Heat Resistant Layer (~0.3 µm)


Thermal Donor Ribbon

YellowPatch

MagentaPatch

CyanPatch

LaminatePatch

YellowPatch

MagentaPatch

CyanPatch

Picture UnitSome Products Have

Registration Bars

A picture unit consists of patches of yellow, magenta, cyan, and laminate that repeat in the donor spool.


Dye Donor LayerPolymeric Binder

U.S. Patent Number 4,700,207

OO

OR

OR

CH2OR

nR = CH3CO, CH3CH2CO

• Dyes with desirable hue• Compatible with the

binder• Good adhesion to the

subbing layer• Non-interactive with the

slip layer• High dye transfer

efficiency• No sticking to the receiver

20 µm

Optical Image of Magenta PatchU.S. Patent Number 5,387,573


Dye Layer Chemistry

NN

N

O

N

O

O

NH

N

N

O

O

NH

N

N

SN

CN

NN

N

O

N

N

C

H

NN

O

N

SN

C

N

NN

NH O

N

Along with dyes:• Polymeric binder• Plasticizer• Spacing beads• Solvent• Other addenda

U.S. Patent Numbers 4,695,287; 4,698,651; 4,839,336; 4,743,582; 4,866,029; 5.340,789; and 5,340,790

O

O

NH

N

N

N N

N

N

O


Donor Film Base• Thickness affects heat

transfer efficiency• Thicker support

– Requires more heat to transfer an amount of dye

– May be more robust to printing

• Thinner supports – Requires less heat to

transfer an amount of dye

– Facilitates the transfer process

O CH2 CH2 O C

O

C

O

n

Support in this system is generally poly(ethylene terephthalate) (PET) ata thickness of either 4.5 or 6 µm.

D.G. Foster & M.L. Gray, “Media and Equipment Advances in Dye Diffusion Thermal Transfer to Facilitate a Multihead Printer System”, IS&T’s NIP 18: 2004 International Conference on Digital Printing Technologies, October 2002


Ti OR

OR

OR

H2OTi

OR

OR

Ti(OR)4 Ti

OR

OR

O Ti OR

OR

OR

H2OTi(OR)4Hydrolysis of Ti(OR)4

Donor Adhesive/Subbing Layer

RORO RO OH

• High adhesion to support & dye layer

• Impermeable to dyes• Low affinity to dyes• Antistatic

OTi

OR

OR OR

Ti OR

OR

OR

1. U.S. Patent Number 4,737,4862. S. Neuman, “Titanium Alkoxide Subbing Layer Chemistry,” 10th International Congress on Advances in Non-Impact Printing, Oct 1994

Ti

OR

OROH2O(RO)n(TiO)y(TiO2)zTi(OR)4


Slipping/Heat Resistant Layer

Rough Surface Cleans Printhead.

• Low & constant friction over entire printing temperature range

• Non-contaminating to print head

• Not abrasive to printhead• Good adhesion to the

subbing layer• Non-interactive with dye

layer when spooled

Slip layers contain lubricants, polymeric binders, solvents, and other addenda to achieve printing.

U.S. Patent Application Publication No. 2005 0009699, Jan 13, 2005U.S. Patent Application Publication No. 2005 0009799, Jan 13, 2005


Laminate – Over Protective Layer

• Thermal dye transfer prints without a protective laminate layer are susceptible to density loss due to – faster light fade of dyes near the surface– attack by ozone, nitrogen dioxide, or sulfur dioxide– other organic chemicals such as those from human fingerprints– dye retransfer to other surfaces in contact especially to materials

like PVC

• A thin protective layer laminated on the final print at the last step of printing has proven to be a very robust method to eliminate or greatly minimize these problems


Two Laminate Options: Glossy and Matte

Dye Receiving Layer

Paper Support

Glossy Surface

Expancel beads are hollow beads that are thermally expanded during the lamination step, interrupting the gloss of the surface.

Matte Surface

Clear Laminate

U.S. Patent Numbers 6,362,132 and 6,184,181


Matte DonorSEM photos of microspheres in donorSEM photos of microspheres in donor

Higher magnification showshow far out of the polymer

layer the microspheres protrude

Rows ofmicrospheres

from gravure coating

J.J. Hastreiter and W.H. Simpson, “Matte Finish on Thermal Prints”, IS&T’s NIP 20: 2004 International Conference on Digital Printing Technologies, October 2004, page 976


Thermal Receivers

• Thermal transfer can take many forms– Label stock– Transparency (loosing ground due to video projectors)– An intermediate receiver that is laminated to a final surface

• For all thermal applications, the receiver must be smooth, because thermal printing is a contact process– The receiver is either a card or has the look and feel of a

photograph. Other kinds of receivers have met with limited success

– Receiver has a big role in thermal management


Thermal ReceiverBasic Structure Schematic

Requirements

U.S. Patent Numbers 6,362,131; 5,853,965; 5,866,282; 5,874,205; 5,888,643; 5,888,681; 5,888,683; and 5,888,714

• High dye uptake• Compatible with dyes• Not easily deformed by heat

and pressure• No sticking to dye donor

during printing• Insensitive to humidity• Good scratch and abrasion

resistant• No stack blocking• Good image stability: light

fade, dark fade, dye retransfer, smear, fingerprint, etc.

• Robust picking & transport

Support Requirements• Smooth surface• No curl at most environmental conditions• Compliant to give good uniformity• Thermal insulating• Antistatic

Paper support

Tie layer

Dye Receiving Layer (~3µm)

Micro-voided film

Tie layer

Anti-curl layer


Thermal Receiver Cross Linking

R NCO + R' OH R N CO

O R'H

isocyanate alcohol urethane


Thermal Receiver Cross Linking

C

CH3

CH3

O C OCH2CH2OCH2CH2O

O

O HCOCH2CH2OCH2CH2O

O

H

n=5 to 6

C

CH3

CH3

O C OCH2CH2OCH2CH2O

O

OCOCH2CH2OCH2CH2O

O

n=5 to 6

N

N

N

O

OO

(CH2)6NN(CH2)6 CC

H H OO

(CH2)6N

H

C

O

N

N

N

O

OO

(CH2)6NCOOCN(CH2)6

(CH2)6NCO

+

LMW Bisphenol A diethyleneglycol polycarbonate

HDI trimer

Crosslinked polyurethane

Advantages: Image density, Tg influenced by plasticizer, Compatibility with Dyes, Light Stability.

T.M. Kung, D. Bailey, B. Pope & G. Bodem, “Development of a Cross-Linked Imaging Layer for Thermal Dye Transfer Receiver”, IS&T’s NIP 20: 2004 International Conference on Digital Printing Technologies, October 2004, page 988


Dye Receiving Layer Components Goal:Curve Shape and Robust Performance

• Polyols– Molecular weight– Composition– End group (aliphatic alcohol vs. phenol)

• Cross linking agents

• Catalysts

• Solvents

• Other addenda – surfactants, plasticizers, release agents, etc.


Image Quality


Image Quality Depends Upon…

• Resolution • Density Range

High Resolution Low Resolution Low DensityHigh Density



• Tone Scale Continuous Tone

Print Density

Input Signal to PrinterRed – Continuous Tone (Thermal Dye Transfer)Green – Bimodal (Wax Transfer & Inkjet)Blue – Multilevel Inkjet

Half Tone



• Color Gamut• Image stability• Print surface• Print durability• Physical

appearance

SmallLarge


Thermal Printing Media:PVC Retransfer Test (7 days, 50°C/50% RH)

Unlaminated Laminated


Possible Printing Artifacts

• Ribbon folds and “smiles”• Burned pixel or change in resistance → streak• Dirt (on media or printhead) • Dropout (non-printed area) or streak• Thermal smear – buildup of heat in printhead that can

affect the image down the page– Aggravated by fast printing– Can be compensated with algorithms

• Parasitic resistance• Misregistration – in the case of multicolor printing


Customized images have been created/discovered to create artifacts for robustness testing.


Thermal Printer Speed IncreasesKodak 4 x 6 Print

0102030405060708090

100

1999 2000 2001 2002 2003 2004 2005

Year

Prin

t Tim

e in

Sec

onds

4720 printer

4700 printer (90 sec)

6800 printer (11 sec)

6400 printer

6850 (8 sec)


Early Thermal Printers

1989 First page-sized printer• 8 dots/min• 20 msec/line• 8.5 × 11 or 11 × 11 in.

Kodak XLS 8600 PS printer• Introduced in 1994• 4 msec/line• 12 dots/min• Clear protective laminate


Kodak Thermal Printer Portfolio

Kodak Professional 4700 photo printer Kodak Professional 8670 PS thermal printer

– 4 × 6 & 4 × 7 inch – Photo grade &

sticker prints– Cartridge load

donor

– Page size – Prints mono,

RGB & CMYK

Kodak Professional 8660 thermal printer Kodak Professional 8500 digital photo printer– Cartridge load

donor– Multiple

output sizes– Network

connectivity

– First Kodak pageprinter under$1000


Two Roll-Fed PrintersIntroduced in 2002

Kodak Photo Printer 6400thermal printer

Kodak Professional ML-500 digital photo print system

– Roll-fed receiver intended for kiosk application

– 4 × 6 inch print in 26 sec – Lower media cost

– 13 sec per 8 × 10 in. print (270 prints per hr) – 4 Printheads – Variable print length (Up to 500 ft)


Kodak EasyShare Printer Dock Plus(Announced – August 2004)

• Prints in 60 seconds• Exposure correction

built into the printer• Capability of printing

wirelessly (Bluetooth)• Built in memory card

slot


Kodak’s 2005 Thermal Printers and Kiosks

Kodak Photo Printer 6800• Roll fed receiver with a single

printhead, intended for kiosk applications

• 11 second prints, at a price that enables 2 printers/kiosk, for a net of pictures in 5.5 seconds

• Features higher productivity and somewhat lower media cost

Kodak Picture Kiosk G-3 Print Station

• Multiple configurations, with page size and 4 × 6 printers

• Can be equipped with Bluetooth and IR wireless capability for printing from PDAs or cell phone cameras

• Multiple digital inputs


Kodak Picture Maker G3 Print Station

• A bundled system of monitor, processor with CD-ROM, memory card reader, floppy disk, flat-bed scanner & thermal printer(s)

• Makes copies from original prints, CDs, picture cards from digital cameras, FLASHPIX CD & JPEG images on diskettes

• Zoom, crop, red-eye reduction, image restoration & text entry

• Touch-screen controls


People to Thank…Maurice GrayElaine BarrettJake Hastreiter

Teh-Ming KungBill Simpson

George BodemJohn CormanRob Gutierrez

Richard HenzelChuck Christ

Documents

Thermal Printing Chemistry for Digital Outputdafoster/Papers... · Slip Layer/Heat Resistant Layer ... Neuman, “Titanium Alkoxide Subbing Layer Chemistry,” 10th International