Radiation Curable Additives Enabling Excellent Paint …...The information contained herein represents Coating Resins' best knowledge thereon without constituting any express or implied

RADTECH North America – April 2013

Paulo Roberto Vieira Jr, PhD

Radiation Curable Additives Enabling Excellent Paint Surfaces

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When and why do we need additives?

• Introduction

• Leveling and Flow

• Foam

• Rheology

MODAFLOW® , CYCAT®, ADDITOL®

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• Introduction


• Foam

• Rheology


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• Defects in the paint film are deviations in evenness and uniform smoothness of the paintsurface and are judged to be an indication of an imperfect coating process.

• Most defects are related to surface tension phenomena, which arise in a liquid because theforces in the air/liquid interface differ from those inside the liquid phase. To prevent orreduce such defects, flow and leveling additives are used.

• Examples of defects: orange peel, brush marks, peaks, craters, fish eyes, and pinholes.



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Surface tension effects drive two different mechanisms of flow:

1. To minimize the surface area of a liquid;

2. To minimize the surface tension differential (or surface tension gradient) to cover areas/liquids of high surface tension with lower ones.

Observation:Besides Surface Tension Differential, flow and leveling are influenced also by the following factors:

‐ Surface Roughness of the Substrate‐Wet Film Thickness‐ Rheological Behavior after Application‐ Drying Time/Flash Off Time and Speed of Solvent Evaporation

Surface Tension


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The concept of the surface energy can be more easily understood when looking to aliquid as an example. Atoms and molecules of the liquid may freely move in order to reachpositions with lower potential energy (thermodynamics law). In other words, a “place” where theforces (attractive and repulsive) acting in all directions are in equilibrium. On the other hand theparticles in the surface of the material experience only forces directed to the center of the liquid.

Due to this, the surfaces are always high energy regions. And precisely this difference between theenergies on the surface and on the interior is called SURFACE TENSION.

Surface Tension – Concept


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• Introduction


• Foam

• Rheology


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Coating

Substrate

Liquid attraction forces (surface tension of the fluid)

Repulsive forces of the solids towards flow (surface tension of the solid)

Ideal ‐ Substrate wetting: Substrate Surface Tension > Coating Surface TensionGood film establishment: Adhesion, Leveling, Flow, Gloss, D.O.I. (Image Definition).

Surface Tension – Substrate Wetting


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Surface Tension in Radiation Curing

A challenge in radiation curing formulations when dealing with SURFACE TENSIONcomes from a often polar profile of the regularly used components, which leads to higher liquidsurface tensions (or energies), impacting the leveling and mainly adhesion on some substrates.

This polarity is essentially determined by the type and number of functional groups.Polar groups, such as hydroxyl or carboxyl groups, increase the surface tension, while nonpolargroups, such as long alkyl chains, siloxanes, or (fluoro)alkyl groups, reduce it.


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Defects What happens in a non-ideal situation?

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Defects What happens in a non-ideal situation?

Example: Cratering


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(Meth-) Acrylic copolymers

Silicones

Fluoro surfactants

Fixing the Defects - Chemistries


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(Meth-) Acrylic Copolymers

No surface tension reduction

R1

C CH2

C O

O

R2 n

R1 = H ( Acrylate )CH3 ( Methacrylate )

R2 = AlkylPolyester/PolyetherSaltHO-functionalCOOH-functional


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Silicones

Modes of action depends on


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Silicones

Polydimethylsiloxanes

CH3

Si O

CH3

Si (CH3)3(CH3)3 Si O

X

2 – 27Levelling

45 - 230Slip

380 - 1500Defoaming

1800 - 2900Special Effects

X =


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Silicones

Modifications

Reduction of surface tension and/or slip improvement

Y Z

CH3

Si O

CH3

Si O Si (CH3)3(CH3)3 Si O

OrganicModific.

AlkylPolyesterPolyetherAlkylReactive:AcrylCOOHOH

mN/mCH3 21CH2CH3 26(CH2)9CH3 32


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Silicones


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Silicones and Interlayer Adhesion

Dosage

Cure Temperature

0,1%0,01% 0,2%

130°C/270°F

150°C/300°F

170°C/340°F

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Fluoro Surfactants


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Example


ADDITOL® VXW 6503 N

Market standard

• Mobile polymer design for optimal dynamic surface tension reduction. Surface tension (< 22 mN/m)

• Low foam stabilization • Strong anti-crater efficiency • No influence on interlayer adhesion

• Comparable efficiency with Fluoro modified polymers.

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• Introduction


• Foam

• Rheology


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Incorporation of Air and Foam Generation

Production

Pumping and filtration

Manipulation

Application

During lacquer manufacturing

Application (airless/airmix)

Chemical reaction (e.g. NCO/H2O)

Porous substrates

!! Stabilised by the use of surface active substances - Surfactants !!

In some radiation curing formulations, foam can be a critical factor. The viscosity andrheological patterns, as well as the application conditions including the cure speed, can results in amore stabilized foam in the paint. Conventional actions such as viscosity lowering, addition of co‐solvents, and decreasing line speed, does not effectively collapse the foam. In this case, the use ofadditives are a very important part of the formulation.


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Foam Generation – Stabilizing effects

HydrophobicHydrophilic

Air

Liquid

Lamella

Air/Gas

Air/Gas

Gibbs elasticityMarangoni effectElectrostatic effectsHigh surface viscosity


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Foam Generation – Negative Impacts

Blisters Pinholes

Macro Foam MODAFLOW® , CYCAT®, ADDITOL®

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Foam Generation

Negative impacts

Poor pigment grinding

Increase of volume

Blisters

Pin holes

Poor gloss

Reduction in film quality

Foam prevention or destruction by using Defoamer and Air-release

Agents


Formulation

DeaeratorDefoamerOrg. modified silicones

Silica

Waxes

Aliph. / arom. Mineral oils

Silicone oils

Special polymers

Fatty acid derivatives

Org. modified silicones

Aliph. / arom. Mineral oils

Silicone oils

Special polymers

Fatty acid derivatives

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Com

patib

le

Effic

ient

StartMODAFLOW® , CYCAT®, ADDITOL®

ADDITOL® VXL 4951N “Best in class” for

Leveling/Defoaming on UV/EB formulations

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Defoaming and Air Release agents

Interface

Macrofoam

Microfoam

DEFOAMER

AIR-RELEASEAGENTS

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Defoaming mechanism

Air

DEFOAMERLamella

Deaerating mechanism

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Destabilising effect

Apolaric substance


Deaerating mechanism

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Coalescence

Apolaric substance

V ~ r2

η

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• Introduction


• Foam

• Rheology


Rheology

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Rheology is the study of the flow, or movement, of a substance in liquid formor solid under conditions where it exists a flow profile in stationary conditions undershear forces (e.g. agitation, roll application, spray gun pressure). The Rheological profile ofa fluid impacts directly on its applicability, drying, leveling, gloss and substrate wetting.

* OBS.: Radiation curing formulations are 100% solids fluids with a flow profile.

Thickeners

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Inorganic Organic

Associative Thickeners

Water-Phase

Starch derivatesCellulose derivates

Acrylic derivates

Associative cellulose ethersAssociative acrylic thickenersPUR - Thickener

Montmorillonite

Hectocrite

Silica


Associative Thickeners – MechanismADDITOL® VXW 6360 / ADDITOL® VXW 6388

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Conclusions

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• Adjusting rheological profiles, leveling & flow parameters and breaking down the stabilized foam. Important characteristics in radiation curing coatings;

• Fixing defects and resolving deviations from the evenness and uniform smoothness of the paint surface, improving the final performance of the coating and optimizing the quality of the film leading to excellent finishes.

Additives play an important role on:

More info:

Latin America –Paulo Roberto Vieira Jr, PhDEmail: [email protected]

North America –Gary KlineEmail: [email protected]

Europe –Thomas SchoenbacherEmail: [email protected]

Asia –Yogesh DhamalEmail: [email protected]

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Thank you!

Disclaimer: Cytec Surface Specialties SA in its own name and on behalf of its affiliated companies (collectively, "Coating Resins") decline any liability with respect to the use made by anyone of the information contained herein. The information contained herein represents Coating Resins' best knowledge thereon without constituting any express or implied guarantee or warranty of any kind (including, but not limited to, regarding the accuracy, the completeness or relevance of the data set out herein). Nothing contained herein shall be construed as conferring any license or right under any patent or other intellectual property rights of Coating Resins or of any third party. The information relating to the products is given for information purposes only. No guarantee or warranty is provided that the product and/or information is adapted for any specific use, performance or result and that product and/or information do not infringe any Coating Resins and/or third party intellectual property rights. The user should perform its own tests to determine the suitability for a particular purpose. The final choice of use of a product and/or information as well as the investigation of any possible violation of intellectual property rights of Coating Resins and/or third parties remains the sole responsibility of the user.

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© Cytec Surface Specialties SA 2013

In early April 2013, Cytec Coating Resins became an Advent International portfolio

company. Please visit us at www.mycoatingresins.com.

Documents

Radiation Curable Additives Enabling Excellent Paint …...The information contained herein represents Coating Resins' best knowledge thereon without constituting any express or implied