Randy A. Johnson, Ph.D.Technology ManagerAshland Performance Materials

New Fast Curing Aliphatic Laminating Adhesives Reduce Waste

and Energy Consumption

2008 AIMCAL Fall Technical Conference

October 19-22, 2008Myrtle Beach, SC

© 2008 Ashland

Composite PolymersWhy Flexible Packaging Adhesives?Flexible packaging adhesives are used to protect graphics and add utility to a package by bonding two or more films together

0.7 mil clear OPP

Printing Ink

Adhesive

1 mil white OPP

• Laminated packages can haveexplosive graphics and unique mixes of aggressive ingredient resistance

• Laminated labels are scuff and scratch resistant and very glossy

Example lamination for packaging

Composite PolymersHow Do They Work?

Tested by pulling apart one inch strips of laminated films

Tested by folding a one inch strip of laminate, heat sealing the inner film surface to itself, and then pull apart

Tested by dragging a weighted piece of film across another piece of film and measuring the resulting force

Tested by making & filling small pouches with product. Accelerated aging done in ovens. Inspect and test for deteriorated appearance or bonds.

Bond Strength Heat Resistance

Coefficient Of Friction(COF) Aggressive Ingredients

Composite PolymersFlexible Packaging Converting Process

Film, foil and / orpaper substrate Substrate is printed

Web substrates are laminated together

Wide web laminated rolls are slit

Rolls converted to bags or pouches and filled

Finished product

10 Color Central Impression Printing Press

Horizontal Form, Fill, Seal Equipment

Solventless Laminator1 2 3

4 5 6

Composite PolymersHistorical Background for Solventless Laminating Adhesives in Flexible Packaging

• R&D: 1960s

• Final developments in 1970s

• Market introduction in late 1970s

• First 5 roller coating unit in early 1980s

• Market success:

• Europe in mid-1980s

• North America mid-1990s

Composite PolymersSolventless Laminator

Photo courtesy of Nordmeccanica® Solventless Laminators

Composite Polymers

Typical Properties of the Adhesive– Two components:

1. Polyisocyanate (usually MDI-based)2. Curative (polyol)

– Low initial mixed viscosity (1,000 – 3,000 cps); reaction begins immediately after mixing the two components.

– Slightly over-indexed with isocyanate– Low-to-zero green bond off-line; requires high

tension control coater. – Cure rate is typically 1-3 days.

Solventless / Solvent-free Urethane Laminating Adhesives

Composite PolymersAdvantages in Solventless Laminating

• Smaller capital investment (i.e., lower cost laminator, no ovens, no incinerator)

• Less energy (no ovens or incinerator)

• Lower coat weight

• Higher production speed

• No solvent costs or VOCs

• Smaller floor space requirement

• Aromatic solventless adhesives are typically less expensive on a dry pound compared to solvent-based adhesives

Composite PolymersDisadvantages of Solventless Adhesives

• Low-to-zero green bond; unable to laminate and slit films in-line

• Poor balance of long pot-life and fast full cure; especially for aliphatic urethane adhesives

• 3 – 10 days to cure is typical

• Hot rooms typically used to force cure adhesive in shorter time. Hot room can cause heat sensitive films to curl in laminate

Composite PolymersPot Life of Typical Aliphatic Laminating Adhesives

Pot-life too short;Full cure acceptable

Pot-life good;Full cure slow.

0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6 7 8

Time (Hours)

Visc

osity

(cps

)

Control 1 - CatalyzedControl 2 - Uncatalyzed

Composite PolymersDSC Cure Rate of Typical Aliphatic Laminating Adhesives

0102030405060708090

100

0 1 2 3 4

Time (days)

% c

onve

rsio

n Control 1(4 days)

Control 2(> 4 days)

Composite PolymersProject Goal

Develop aliphatic urethane adhesive technology that provides flexible packaging converters an adhesive with good balance of long pot-life with faster full cure.

Composite PolymersBackground:Trigger Cure Aliphatic Urethane Coatings

US Patent 4,788,083 Dammann, L.; Carlson, G.; 1988.

excessR”-SH

aliphatic isocyanatemonomer / prepolymerin solvent

curative polyolwith blocked catalystin solvent

mix extendedpot-life

NR3

Δaliphatic polyurethane coating+

active catalyst blocked

catalyst

Composite PolymersInitial Attempt at Implementing Blocked Catalyst into Solventless Laminating Adhesives

aliphatic isocyanatemonomer / prepolymer

curative polyolwith blocked catalyst(30 : 1)

+ mix unacceptable pot-life (< 2hrs)

Viscosity Cure profile @ 35 C

0

20

40

60

80

100

120

0 20 40 60 80 100

Time (minutes)

Visc

osity

(poi

se)

short pot-life Shift longer

Composite PolymersVariables Effecting Blocked Catalyst Reactivity

1. Ratio of catalyst to blocking agent

2. Type of catalyst and blocking agent

3. Time

4. Temperature

5. Formulation

Composite Polymers1. Effect of Ratio of Catalyst to Blocking Agent

Viscosity Cure Profile @ 35oC

0

20

40

60

80

100

120

140

0 50 100 150 200

Time (minutes)

Visc

osity

(Poi

se.

TMPTMP / T-12 (30 : 1)

TMPTMP / T-12 (45 : 1)

TMPTMP / T-12 (60 : 1)

Composite Polymers2. Effect of Type of Blocking Agent

Viscosity Cure Profile @ 35oC

0

20

40

60

80

100

120

0 20 40 60 80 100

Time (minutes)

Visc

osity

(Poi

se)

mercapto-silane / T-12 (30:1)

TMPTMP / T-12 (30:1)

Composite Polymers3. Effect of Time

Sample 11 - TMPTMP / T-12 Ratio 60 : 1 curative stored at @ 40oC

020406080

100120140160

0 100 200 300 400

Time (minutes)

Visc

osity

(Poi

se)

Initial1 week2 weeks3 weeks4 weeks5 weeks6 weeks

Composite Polymers4. Temperature

Viscosity Cure Profile Heat Treated Curative with

mercapto-silane / T-12 (30 : 1)

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120 140

Time (minutes)

Visc

osity

(Poi

se) . Initial

75C for 1hr100C for 5hr125C for 3hr

Composite Polymers5. Formulation Effect

• Sample 1 – tested immediately (time zero)

• Sample 2 – curative from Sample 1 stored at 60C for 4 weeks before testing –pot-life increased substantially

• Sample 3 – same curative, but only blocked catalyst mixture stored at 60C for 4 weeks – formulated into curative and ran immediately – no change in reactivity

Viscosity Cure ProfileCuratives with mercapto-silane / T-12 (30 : 1)

020406080

100120140160

0 50 100 150 200 250 300

Time (minutes)

Visc

osity

(Poi

se)

Sample 1Sample 2Sample 3

Composite PolymersHow is the Catalyst / Blocking Agent Working?

Proposed blocked structure

excessR”-SH

blocked catalyst

active catalyst

Composite Polymers117Sn NMR Analysis of Catalyst DerivativesT-12

T-12 in polyol mixture

Blocked T-12

FC-13.5 b

FC-14 wk5

-200-150-100-50200 150 100 50 0 ppm

Expt. Time (hour)

0.5

0.5

5.5

18

62

Apodization: 20 Hz line broadening

Curative - initial

Blocked T-12

T-12 in Curative polyol mixture

Curative – stored at 60C for 5 weeks

T-12

Tin signal becomes severely attenuated and / or dispersed with aging and heat. The electronic environment around the tin has changed significantly.

Composite Polymers117Sn NMR Analysis of 10% Loaded Blocked Catalyst

- Temperature and Time Effect

Even at 10% blocked catalyst loading, the signal is severely attenuated / dispersed with elevated temperature and time.

-250-200-150-100-50200 150 100 50 0 ppm

9564B: after 48 h at 125 C

9564A: after 15 h at 60 C

9564 (no heat treatment)

Composite PolymersResults

Viscosity Cure Profile with TimeComparing Improved Cure Adhesives vs Industry Standards

0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6 7 8 9 10

Time (Hours)

Visc

osity

(cps

)

Improved Cure 1Improved Cure 2Control 1 - poor potlifeControl 2 - slow full cure

Composite PolymersTemperature Effect on Final Cure Times (DSC)- Improved Cure Formulation 2

0102030405060708090

100

0 10 20 30 40 50

Time (hrs)

% C

onve

rsio

n

25C cure

35C cure

Composite PolymersDoes It Stick?

Bond strengths (gli)

0

1000

PET/PE -(tear)

MET/PE - (adh)

Besela*/Cast prop - (tear)

Besela*/Nylon - (tear)

PLA/PLA -(adh)

PET(PVDC coated)/PE-(tear)

Besela*/PE - (tear)

Celplast**/PE - (adh)

Nylon/cast prop - (tear)

OPP/PE (bonds)-(tear)

Improved Cure 2Control 2

*Besela is a registered trademark of Kureha Corporation**Celplast is a trademark of Celplast Limited

Composite Polymers

OPP/PE PET/PE PE/PEDog food + + +

Vinegar + + +

Tomato sauce + + + OPP DISCOLORATIONSweet-sour sauce + + +

French dressing + + + SLIGHT DISCOLORATIONGround cinnamon + + +

BBQ sauce + +WB +

Ketchup + + +

Iodine swab + + + DISCOLORATION ON ALLVegetable oil + + +

Coffee + + +

Hazelnut coffee + + +

Mineral oil + + +

Chocolate syrup + + +

chewy candies + + +

IPA + + +

Rice + + +

Chlorine granules + WB + WB +

Herbicide + + WB +

Turfbuilder + + WB +

Baby wipes + + +

Fruit punch + + +

Kiwi straw. Juice + + +

Apple juice + + +

+ Indicates film PASSED ingredient test- Indicates film FAILED ingredient testWB = Weak bonds after ingredient testing

LaminationsCommon Characteristics

Aggressive Ingredient Testing at 60oC for 100 Hours- Improved Cure Formulation 2

Composite PolymersSummary

• Developed long pot-life with fast full cure for solventless aliphatic urethane technology• Blocked catalyst mechanism not well understood

• Variables influencing blocking / deblocking are well understood and controllable

• New technology has been incorporated into solventless aliphatic urethane adhesives and provides converters the benefit of long pot-life and fast full cure for both food and industrial laminates

• Patent application pending

Composite PolymersAcknowledgements

Project Team• Dr. Sridevi Narayan-Sarathy• Dr. Greg Booth• Keith King• Jim Emrick• Jim DiThomas• Bill Smart

Ashland Performance Materials

Thank YouPRESENTED BY

Dr. Randy A. JohnsonTechnology ManagerAshland Performance Materialsrajohnson@ashland.com