new fast curing aliphatic laminating adhesives reduce waste … · paper substrate substrate is...
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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 [email protected]