Cohesive strength development

Reactive Latexes

Film Formation and Properties

Short Course from NPTL, 5 OCT 2000, Yonsei Univ. Korea

박 영 준

HANWHA CHEMICAL R&D CENTER

HANWHA CHEMICAL RESEARCH & DEVELOPMENT CENTER

• Polymer Resins

• Chemical Processes

• Fine Chemicals

• Environments

HANWHA CHEMICAL CO.

1 Janggyo-dong, Chung-ku, Seoul, KOREA tel : +82-2-729-1236 fax : +82-2-729-1450 E-mail: jtcho@hanwha.co.kr

For the Ink and Coating Industry

Hanwha SOLURYL Solid & Emulsion Resins

http://rne.hanwha.co.kr

For detailed information, please visit our site.

SOLID RESINS

•Alkali soluble styrene-acrylic resin

• Pigment dispersing agent

• Water-based inks and overprint varnishes

EMULSION RESINS

• Styrene-acrylic emulsion

• Letdown and overprint

• Newtonian flow behavior

• Excellent gloss & color development

SOLURYL R-20, SOLURYL R-90, SOLURYL E-80 SOLURYL-50, SOLURYL-70, SOLURYL-120

CONTENTS

• Introduction : Reactive Latex

• Thermal Crosslinking System

• Ambient Crosslinking System

• Prospects

INTRODUCTION

• Crosslinking : Enhancement of the integrity of polymer films

 Impact strength, tensile strength, peel strength

 Water, alkali & chemical resistance

• Homogenously crosslinked film : crosslinking agent (DVB)

 Lack of crosslinking at the particle-particle interface

 Hinderance of the strength development process of polymer chain interdiffusion

 Loosely fused film of individually x-linked polymer particle

• Crosslinkable polymer latexes : Latent crosslinking

Reactive Latexes : Latent Crosslinking

• Latent crosslinking : After the polymerization step

- Incorporation of various functional groups capable of undergoing crosslinking reaction

- Crosslinking reaction after particle coalescence stage : No hinderance to polymer chain interdiffusion

 Improvement of mechanical properties

Type of Crosslinking

Deformation Evaporation /

Interdiffusion

Interdiffusion / Interfacial x-linking

Homogeneous x-linking

Interstitial x-linking

Cohesive strength development

E.S. Daniels and A. Klein, Prog. in Org. Coatings, 19, 359 (1991)

Interfacial x-linking

Homogeneous Crosslinking

• X-linking reaction within the particle and at the particle surface - Incorporation of functional groups capable of

self-condensation or auto-oxidation

• Self-condensation : N-methylol methacrylamide, hydroxy-methylate diiacetone-acrylamide, trialkoxysilylpropyl(meth)acylates - Premature x-linking due to hydrolysis

• Auto-oxidation : cyclohexenyl acrylate, ally acrylate

Interfacial Crosslinking

• X-linking reaction at the particle boundaries between adjacent particles during particle coalescence and film formation

• Carboxy-functional latexes : (meth)acrylic, maleic, etc. acid

- x-linking with metal ions, melamines, urea-formalehyde, epoxy-containing curing agent

• Hydroxy-functional latexes : hydroxyethyl (meth)acrylaye

- x-linking with melamines, urea-formalehyde, isocyanates, epoxy, etc

• Epoxy-functional latexes : glycidyl methacrylate

- x-linking with amines and carboxyl acids, etc

Crosslinking Mechanism

C O OH

O

CH₂ CH CH₂

O O

C

O O

C C

O O CH₂ CH

CH₂ OH

C

O O CH₂ CH

CH₂

O O

C OH C

O CH₂ CH CH₂ O

C

O O CH₂ CH CH₂

O O

C O C

O O CH₂ CH OH

CH₂

• Reaction of epoxy and carboxyl groups

• Celation with zirconium compounds

• Incorporation of methyol functional groups

V. I. Yeliseeva, Br. Polym. J., 7, 33 (1975)

Y. Inaba, E. S. Daniels, and M. S. El-Aasser, J of Coating Tech., 66 (833), 63 (1994)

S. Yoo, L. Harelle, E. S. Daniels, M. S. El-Aasser, and A. Klein, J. of Appl. Polym. Sci., 58. 367 (1995)

Case Study I : Thermal X-linking

♣ Objectives

- Effects of surface functional groups of reactive latexes on

1. Interdiffusion and crosslinking reaction during film formation and annealing process : Dynamic mechanical analysis

2. Deformation and fracture behavior

♣ Model Systems : Reactive latexes -

Preparation of model latex • Variable concentration of functional groups

• Batch polymerization

• Shot growth polymerization

Compression molding / Annealing

• 140 or 170 ^oC for 12 min at 3000 psi

• Annealing time : 0 - 1000 min.

Emulsion blending or

Heterocoagulation / Drying

• Blending of P(MMA/GMA) & P(MMA/MAA)

• 60 ^oC, 24 hrs

J. H. Kim, M. Chainey, M. S. El-Aasser, & J. W. Vanderhoff, J. Polym. Sci. : Part A. Polym. Chem., 27 (1989) 3187

Measurement • DSC, DMTA, SEM

• Instron, Impact strength

EXPERIMENTAL

Cohesive Strength Development : DMA Analysis

•Effect of surface functional group concentration & location

•Effect of annealing time on degree of chain interdiffusion

d

Tensile Strength

d

Time (min)

0 100 200 1000

Tensile Strength (MPa)

0 10 20 30 40 50 60 70 80 90 100

H

Homopolymer

cm^-1

700 800

900 1000

1100

Absorption

0 1 2

(A) Epoxy group

: before heat treatment

(B) After heat teatment

• FT-IR spectra • Tensile strength development

Cohesive Strength Development

Num ber density of surface epoxy group (/nm²)

0.0 .1 .2 .3 .4 .5 .6

Tensile Strength (MPa)

0 10 20 30 40 50 60 70 80 90 100

Blend samples Copolymer samples

(B) After 1,000 min

(A) Initial stage

Number density of surface epoxy group (/nm²)

0.0 .1 .2 .3 .4 .5 .6

Tensile Strength (MPa)

0 10 20 30 40 50 60 70 80 90 100

Blend samples Copolymer samples

Emulsion blend vs. Copolymer : Surface functionality

•J.D. Ferry, Viscoelastic Properties of Polymers, 3^rded., J. Wiley & Sons, New York (1980).

•J. Richards and K. Wong, J. of Polym. Sci., Part B, Polym. Phys., 33, 1395 (1995).

DMA analysis of molecular interdiffusion Analysis of molecular interdiffusion

- Direct non-radio fluorescence energy transfer (DET) - Aattenuated total reflectance FT-IR

- Small angle neutron scattering (SANS)

- Freezes fracture transmission electron microscopy (TEM)

•J.D. Kim, L.H, Sperling, and A. Klein, Macromolecules, 27, 6841 (1994).

• D. Juhue, and J. Lang, Macromolecules, 27, 695 (1994).

• K. Hahn, G. Ley, H. Schuller, and R. Oberthur, Colloid and Polym. Sci., 264, 1092 (1986).

• Y.K. Wang, A. Kats, D. Juhue, and M.A. Winnik, Langmuir, 8, 1435 (1992).

Analysis of molecular interdiffusion

Log a_Tω

-4 -3 -2 -1 0 1

Log J', Log J"

-3.0 -2.5 -2.0 -1.5 -1.0 -.5

Log a_Tω

-4 -3 -2 -1 0 1

Log J', Log J"

-3.0 -2.5 -2.0 -1.5 -1.0 -.5

Homopolymer

2.3910^-16 cm²/sec X-linked Copolymer

1.3110^-17 cm²/sec

Diffusion Coefficient :

dp (nm)

0 10 20 30 40 50

Tensile Strength (MPa)

0 20 40 60 80 100

Homopolymer film Crosslinked film

Interdiffusion effect on the tensile strength development

f_{S = −} R r g_D r dr

∞

1 1

4 3 4

3

2

( / ) 0 ( )

π π

g r erf R r

Dt erf R r

Dt

r Dt R r

Dt

R r Dt

D

diff diff

diff

diff diff

( ) . [ ( ) ( )]

/ {exp( ( )

) exp( ( )

)}

= + + −

+ − + − − −

0 5 2 2

1

4 4

2 2

Π

d r g r t r dr g r t r dr

P R

i Ro D

Ro D

= −

∞

∞





2 2

2

4 4 ( , ) ( , )

π π

• Y. Wang and M.A. Winnik, J. Phys. Chem., 97, 2507 (1993).

• J.P.S. Farinha, J.M.G. Martinho, S. Kawaguchi, and M.A. Winnik, J. Phys. Chem., 100, 12552 (1996).

 Effect of interfacial chain structure

on toughening behavior in PMMA / core/shell particle

Impact Strength Development : K

Analysis

Interfacial zone formation in reactive particle system

Preparation of reactive core/shell particles by Heterocoagulation

Heterocoagulation technique

LP

Large particle (LP) Small particle (SP) Matrix particle (MP)

LP

LP • Heterocoagulated Composite Particles

Shell : COOH group Core : -O- group

Factor

+ Matrix Particles

H-SP-A

Heterocoagulated particle

ID. of SP

Compression molding

LP LP

•

•rubber modified PMMA composite with different interfacial chain structure

Preparation of rubber modified PMMA composite

Amount of COOH on Particle Surface (m C/cm2 )

0 5 10 15 20 25

Critical stress intensity factor (KIC)

2.5 2.6 2.7 2.8 2.9 3.0 3.1

COOH COOH

COOH OC

HO

A

COOH COOH

COOH OC

HO

B COOH

CO OH O C H O

COOH OH CO

O

O O

O O

C

O

O O

O O

C

D

D

Fracture Toughness of Composites

Schematic diagram of formation of chemical linkage between small particles and large particles

1. Attenuated Total Reflectance FTIR (AIR-FTIR) Study of the Latex Film Formation and Crosslinking Reaction of Complementary Reactive Latex Blends

2. Effect of Ambient Crosslinking on the Mechanical

Properties and Film Morphology of Composite Latexes

Case Study II : Ambient X-linking

Film Formation

IR Beam Detector

Latex Dispersion

ATR-FTIR

IR Beam Detector

Film

ATR-FTIR

A schematic illustration for attenuated total reflection FTIR for the in situ study of latex film formation

in Situ Monitoring of Crosslinking Reaction of

Reactive Latexes During Film Formation

AAEMA _O ^O

O

O O

NCO

TMI

O C CH₂ O

C O

CH₃ O C N RT

Acetoacetoxy - Isocyanate

O CH₃ C O

CH C

O NH

O C

♣Objective

- Quantification of interfacial crosslinking reaction between acetoacetoxy / acetoacetamido and isocyanate groups at ambient condition using ATR-FTIR

Acetoacetoxy vs. Acetoacetamido

Amadeus

NH O

O

O O

System : Interfacial X-linking vs. Internal X-linking

O

O O

NCO-

N

O O

( or )

+

(1) Interfacial X-linking

Emulsion Blending

Film Formation

(2) Interfacial X-linking and Internal X-linking

O -NCO

O O

-NCO

Film Formation

O

O O

Monitoring of Crosslinking Reaction

in situ ATR-FTIR

Monitoring of Crosslinking Reaction

1000 1500 2000 2500 3000 3500 4000

0.0 0.5 1.0 1.5

cm^-1

Abs

Figure. ATR-FTIR measurments for reactive latex blend system;

poly(EHMA-co-TMI) - Blend - poly(EHMA-co-Amadeus)

Time (min)

0 200 400 600 800 1000 1200 1400

Abs for -NCO

0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28

2nd stage of crosslinking reaction 1st stage of crosslinking reaction

Film formation and crosslinking reaction stage Water evaporation stage

Kinetics of X-linking Reaction During Film Formation

Monitoring of Crosslinking Reaction O C CH₂

O

C O

CH₃ O C N

O CH₃ C O

CH C

O NH

O C

Time (min)

0 200 400 600 800 1000

Abs for -NCO

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Kinetics of X-linking Reaction During Film Formation

AAEMA + TMI

Time (min)

0 200 400 600 800 1000

Abs for -NCO

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Amadeus+ TMI

Monitoring of Crosslinking Reaction

Blend

Copolymer

Blend

Copolymer

Effective Diffusion Coefficients

Monitoring of Crosslinking Reaction

r_c C T

R

•Diffusion model of complementary cross-linking system

• T: TMI content

• C: Concentration of the AAEMA(or Amadeus)

• R: Particle radius

• r_c:Shrinking radius of the unreacted core (TMI)

J.Xu et al., J. Appl. Polym. Sci., 69, 985 (1998)

De =[R²ρ / (3M C_T )](dT dt/ )[(To T/ )^{1 3/} −1]

•Effective diffusion coefficient

time (min)

0 200 400 600 800 1000

dT/dt (1/sec)

-3.5e-3 -3.0e-3 -2.5e-3 -2.0e-3 -1.5e-3 -1.0e-3 -5.0e-4 0.0e+0

De(cm2 /sec)*E-13

0.0 0.5 1.0 1.5

dT/dt D_e

Effective Diffusion Coefficients

Monitoring of Crosslinking Reaction time (min)

0 200 400 600 800 1000

dT/dt (1/sec)

-1.4e-3 -1.2e-3 -1.0e-3 -8.0e-4 -6.0e-4 -4.0e-4 -2.0e-4 0.0e+0

De(cm2 /sec)*E-13

0.0 0.5 1.0 1.5

dT/dt D_e

AAEMA + TMI Amadeus+ TMI

Tensile Properties

strain (mm/mm)

0.0 0.5 1.0 1.5 2.0 2.5

Stress (MPa)

0 1 2 3 4 5 6 7

Figure. 2. Effect of crosslinking method on tensile properties of poly(EHMA-co-Amadeus) [line] and

poly(EHMA-co-AAEMA) [dot] latex film (1) X-linking with diamine

during film formation

(2) X-linking with diamine after film formation

(3) X-linking with NCO-functional latex

(4) Without X-linking

0 2 4 6 8 10

Tensile strength (MPa)

1 2 3 4 5 6 7 8

AAEMA AMADEUS

Amount of functional monomer (wt.%)

•Effect of the amount of functional monomer •Effect of x-linking methods

Effect of Ambient Crosslinking on the Mechanical Properties and Film Morphology of Composite Latexes

Post X-linking PS/P(BA-AAEMA)

Composite Latex - 50/50 wt.%

Spreading

Film formation

& X-linking External X-linker

O C CH₂ O

C CH₃ O

H₂N -R-N H₂

O C CH O

C N H-R-NH-C

CH3 CH3

CH C O

O 2 H₂O

2

Post X-linking

Effect of X-linking of Rubbery Phase

1. No Crosslinking 2. Crosslinking in the Shell Phase

PS Opaque film with crack PS + ^Diamine PS Opaque film

with no crack

Thermal Annealing at 140C

Transparent film with no crack

Before Annealing : AFM

Post X-linking

Without X-linking

With X-linking

Post X-linking

After Annealing : AFM

Without X-linking

With X-linking

SEM : before x-linking - Fracture Surface

140C, 3hrs

ESEM : After x-linking

140C, 3hrs

T e m p e ra tu re (C )

-1 0 0 -5 0 0 5 0 1 0 0 1 5 0 2 0 0

Tand

0 .0 0 .5 1 .0 1 .5

w ith x-lin kin g w ith o u t x-lin kin g

Temperature (C)

-100 -50 0 50 100 150 200

Log (E')

5 6 7 8 9 10

with x-linking without x-linking

Post X-linking

DMTA

PS PS

PS PS PS

PS PS PS

PS PS PS

+^Diamine PS PS

PS PS

PS PS PS PS PS

PS PS

PS PS

PS PS PS

Latex Dispersion Percolation and X-linking during Film Formation

PS

PS PS PS PS

PSPS PS PS PS PS PS PS

PS PS PS PS

PS PS

PS PS PS PS PSPS PS

PS

PS

PS PS

PS PS PS

PS PS

PS PS

PS PS

PS Restriction of PS phase separation due to x- linking structure

Post X-linking

Effect of X-linking of Rubbery Phase

3. Crosslinking in the Shell Phase : Small sized PS core particle (50nm)

PS PS + ^Diamine

Transparent film with no crack

4. Another 3rd layer of PBA homopolymer : thickness - 10nm

PS

PS + ^Diamine Opaque film with crack

P(BA-co-AAEMA)

Swelling of St monomer AIBN

TBHP

5. Inverted Method

Transparent film with no crack

System 3 : Small PS core - before/after X-linking

X-linking

System 4 : Another 3rd layer

X-linking

System 5 : Inverted Method - AIBN

X-linking

System 6 : Inverted Method - TBHP

X-linking

BA content (%)

50 60 70 80 90 100

Strength (MPa)

0 2 4 6 8 10 12

PS/PBA PBA/PS X-PBA/X-PS

Strain (mm/mm)

0.0 0.2 0.4 0.6 0.8 1.0

Stress (MPa)

0 2 4 6 8 10 12

Standard

TBHP

AIBN

Tensile Properties

•Effect of monomer sequence of addition •This Work: PS/PBA + Post X-linking

.M. Narkis, Y. Talmon, M. Silverstein, Polymer, 26, 1359 (1985) .D.I. Lee, T. Ishikawa, J. Polym. Sci., Polym. Chem. Ed., 21, 147 (1983)

.T.I. Min, A. Klein, M.S. El-Aasser, J.W. Vanderhoff, J. Polym. Sci., Polym. Chem.

Ed., 21, 2845 (1983).

•ASR : Process controllable X-linking system (Hybrid)

•Ambient X-linking for composite latex

NH C CH₂ C CH₃

O O

NH₂ NH₂ COOH

+

Water soluble amine copolymer

Emulsion Blending

Film Formation Interdiffusion

/Crosslinking

High Tg Core

• Low Tg Shell with x-linkable

functional groups • External X-linker

RT

•High Tg Core

Low Tg Shell >>1

Significant improvement of physical properties

PROSPECTS