radiation-cured components & their use in hard, scratch resistant coating applications
TRANSCRIPT
Radiation-Curable Components and Their Use in Hard, Scratch-Resistant Coating Applications
Presentation Topics of Discussion
! Current and potential hard coat applications.
! Description of products tested and their attributes.
! Taber haze and Taber abrasion resistance ● Surface scratch resistance ● Abrasion resistance (bulk properties)
! Weathering resistance as a function product type and film thickness.
! Barrier properties (substrate protection) of a typical hard coat formulation. ● Influence that the addition of HALS and absorbers have on
weathering resistance and barrier property performance. ! Polyurethane Dispersion Products (PUDs) ● Overall performance properties ● Abrasion resistance study
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Typical Abrasion Resistant Applications
! Automotive & Architectural Window Film
! Interior and Exterior Automotive Parts
! Sporting Goods Including Skis, Snow Boards, Surf Boards & Golf Balls
! Helmets Visors and Goggles
! Ophthalmic Lens
! Cell Phones
! CD & DVDs
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Highly Functional Urethane Acrylate Oligomers for Hard Coats
Attributes & Test Results
4
Weathering Resistant Urethane Acrylate Structure
OHNO
HN
OO
HN O
O
HNO
O
PolyolR
OR
O
Di-isocyanate Di-isocyanate Acrylating GroupAcrylating Group
l Aliphatic Di-isocyanate
l Polyester Polyol
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Hard Coat Oligomers, Attributes & Hardness Test Results
Oligomer Acrylate Groups
Attribute Tg C by
DMA
Pencil Hardnes
s
Konig Pendulum Hardness
0000 Steel Wool Resistance, 50 Cycles, 1.0 Kg
Weight
CN9006 6 Fast curing with proven weathering performance.
77.25 8H 116 Pass
CN9026 6 More flexible with improved resiliency.
74.41 7H 98 Pass
CN9025 6 Higher Mw with lower toxicity.
80.0 7H 103 Pass
CN9013 9 Very fast curing with enhanced stain resistance.
135.0 7H 128 Fail
CN120 2 Lower cost with good chemical resistance
138.0 9H 138 Fail
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Taber Testing of Urethane Acrylate Oligomers
! Tabered Haze Testing
! Surface Scratch Resistance
! CS-10F wheel under 500g load for 10 cycles
! Taber Abrasion Testing
! Wear Through Resistance Properties
! CS-17 Abrasion Wheel
! Weight loss every 500 cycles to 2,000 cycles
! 1,000g load on each Taber wheel
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Tabered Haze Testing
Application & Cure Conditions
! Neat Oligomer Tested ● Cut in 50% Acetone
! Film Thickness: 3-6 microns (after flash off)
● #5 wire bar used ● Acetone flashed off prior to cure
! 50 fpm under (2) 300 w/in “H” lamps
! CS-10F wheel under 500g load for 10 cycles
Delta Haze Results
1.5
2.8 3.1 3.2
8.9
0
2
4
6
8
10
12
CN9006 CN9026 CN9025 CN9013 CN120
InitialTaberedDelta Haze
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Taber Abrasion Testing
0
25
40
55
70
85
0
2128
3645
60
0
2333
4455
70
0
30
50
75
92101
0
40
70
96
120
140
0
20
40
60
80
100
120
140
160
0 100 Cycles 200 Cycles 300 Cycles 400 Cycles 500 Cycles
Weight Loss
CN9006CN9026CN9025CN9013CN120
CS17, 500g Load Mg of Weight Loss per 100 Cycles
(Base Formulation Tested: 75% Oligomer, 20% Monofunctional Diluent, 5% Alpha Hydroxy Ketone)
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Scratch & Abrasion Resistance Conclusions/Observations
! Aliphatic urethanes with high acrylate functionality result in cured films having excellent abrasion resistant properties.
! High functionality results relate to a high crosslink density. This may result in micro-cracking of the cured film when coating thickness exceeds 5 microns.
! This can be controlled by modification of the backbone structure to impart better flexibility or addition of lower functionality acrylates to the formulation.
! These modifications and additions can improve the ductile properties of the film, making it malleable.
! This results in cured film with abrasion resistant qualities, while improving the overall scratch resistance.
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Weathering Resistance as it Relates to Oligomer Structure & Cured Film Thickness
Test Methods & Results
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QUV Equipment & Conditions
! 8 hours of UV radiation @ 60 C
! Followed by 4 hours dark condensation @ 40 C
! The lamps were replaced every 400 hours to ensure constant UV intensity.
! The bulb used was a UVA 340 from Q-Panel. The output is from 300 - 400 nanometers centered at 340 nm.
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Gloss Retention & Yellowing Resistance
Gloss: ASTM D523-89 @ 60°
Yellowness Index: ASTM E 313-98
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Gloss Retention Rating Scale
! Good = 0‒7 points of gloss loss
! Slight = 8-15 points of gloss loss
! Severe = >15 points of gloss loss
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Degree of Micro-Cracking as it Relates to Oligomer, Film Thickness & QUV Exposure
Oligomer& Film
Thickness
0 QUV
100 Hours
300 Hours
500 Hours
700 Hours
1000 Hours
1500 Hours
2000 Hours
3000 Hours
4000 Hours
5000 Hours
CN9006 5 micron
Good Good Good Slight Slight Slight Slight Severe Severe Severe Severe
10 micron Good Good Good Slight Slight Slight Severe Severe Severe Severe Severe
15 micron Good Good Slight Slight Severe Severe Severe Severe Severe Severe Severe
CN9025 5 micron
Good Good Good Good Good Good Good Good Good Good Slight
10 micron Good Good Good Good Good Good Slight Severe Severe Severe Severe
15 micron Good Good Good Good Good Slight Severe Severe Severe Severe Severe
CN9026 5 micron
Good Good Good Good Good Good Good Good Good Good Good
10 micron Good Good Good Good Good Good Good Good Good Good Good
15 micron Good Good Good Good Good Good Good Good Good Good Good
CN9013 5 micron
Good Good Good Good Good Slight Severe Severe Severe Severe Severe
10 micron Good Good Good Good Good Slight Slight Severe Severe Severe Severe
15 micron Good Good Slight Severe Severe Severe Severe Severe Severe Severe Severe
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Urethane Acrylate Hard Coat Summary
! Aliphatic urethanes with high acrylate functionality result in cured films having excellent abrasion resistance properties.
! Higher functionality yields a higher crosslink density, which, in general, is desirable. However, the downside of increased crosslink density can be a decrease in abrasion resistance and an increase in micro-cracking of the cured film during weathering exposure, particularly when coating thickness exceeds 5 microns.
! These limitations can be controlled by modification of the backbone structure to impart increased flexibility or by the addition of lower functionality acrylates to the formulation to reduce crosslink density.
! These adjustments improve the ductile properties of the film making it more malleable, resulting in cured film with better abrasion resistance and a lower propensity for micro-cracking during weathering.
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Barrier Properties of a Hard Coat Formulation
Test Methods & Results
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Weathering Resistance of a Coating on Polyester Film ∆E and Gloss Loss as it Relates to QUV Exposure
Base Formulation Cure & Application Parameters
1) Two 400 W/in “H” Lamps @ Line Speed 50 F/M
2) Power Puck UVA,1.8 J/CM2
3) Film thickness: 5-7 microns, Applied using a # 4 wire bar
4) Viscosity @25C, 820 cps
Component Weight%
CN9026 75.0
Flexible Monofunctional Acrylate
12.0
Low Surface Tension Monofunctional Acrylate
10.0
Irgacure 184 3.0
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Test Method Employed, ∆E Measurements
! BYK Color-Guide Sphere ● CIE Lab ● YE313-98 ● D65/10
! Readings taken on coated 5 mil thick PET placed over a white background for measurement
! ∆E is measure of overall color change
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∆E Test Results as They Relate to QUV Exposure & Stabilizer Package Used
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
100 300 500 700 900 1100 1300 1500 1700 1900
Delta
E
Hours of QUV Exposure
PET
FormulaBon on PET
1.5% UR-‐210
3.0% UR-‐210
1.0% 292 ; 1.0% 400
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Gloss Retention @ 60 as it Relates to QUV Exposure & Stabilizer Package Used
5
25
45
65
85
105
125
145
165
185
205
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Gloss
Hours of QUV Exposure
PET FormulaBon on PET 1.5% UR-‐210 3.0% UR-‐210 1.0% 292 ; 1.0% 400
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UV/VIS Percent Transmittance After 2000 Hours QUV Exposure
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
Nanometers
Perc
ent T
rans
mitt
anc
e
PET Only
Coated PET
Coating w/ HALS on PET
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Barrier Property Performance Observations
! Certain grades of PET will degrade when exposed to heat, light and moisture for extended periods.
! A properly formulated coating can lessen the degradation and protect the PET.
! The addition of HALS and light absorbers can further enhance protection.
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Polyurethane Dispersion Product Study
Overall Properties &
Abrasion Resistance Study
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Liquid Property Overview of UV-Curable Waterborne Oligomers, Polyurethane Dispersions (PUD)
Product Designation
Percent Solids Viscosity @ 25 C, cps
pH
Mean Particle Size (nm)
NTX12784 39-41 10-12 7.3 ‒ 8.0 125
CN9500 40-42 8 - 15 7.3 ‒ 7.9 120
CN9501 39-41 10-12 7.2 ‒ 7.9 140
Control 35 20 8.0 <150
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Waterborne Oligomer Testing, Formulating and Processing
! Formulation: UV-PUD diluted to 35% solids plus standard additives and photoinitiators
! Film Thickness: 6.0 mils wet/2.0 mils dry
! Substrates: Glass (hardness and tensile), Leneta charts (KCMA stain), aluminum panels (MEK resistance and Taber abrasion)
! Drying Conditions: 30 min @ 72oF/50% RH, 30 min @ 60oC
! Cure Conditions: 2 x 400 W/in. Hg lamps @ 50 ft/min
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PUD Test Results
Relative Performance Ranking5 = Best
0 1 2 3 4 5
Hardness
Solvent Resistance
Water Resistance
Stain Resistance
Abrasion Resistance
QUV Yellowing
Flexibility
Control Aquamer 9501 Aquamer 9500 NTX12784
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Waterborne Oligomer Testing
Surface Scratch Testing
! Affix white abrasive pad to a mounting fixture having an area of 1 sq. in.
! Place 100g weight on top of mounting fixture.
! Slide weighted pad back and forth over the surface 50 times at each weight load.
! A back and forth motion constitutes one cycle.
! Measure gloss before and after abrading.
! Report gloss readings.
Gloss Retention
6065707580859095
100 200 300 400 500
Double Rub Cycles
Gloss @
60
Control PUD
CN9501
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Taber Abrasion Resistance, CS 17, 1000g Load
0
13
24
33
42
49
0
915
2529
32
0
9
18
29
36
45
0
10
20
30
40
50
60
0 200 400 600 800 1000
Taber Cycles
Weight Loss, milligrams
NTX12784
CN9500
CN9501
Control
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Waterborne Oligomer Observations
! The family of UV-PUD materials examined offers a higher reactive solid content at a lower viscosity when compared to typical UV-PUDs on the market.
! These features provide greater formulating latitude for industrial coatings.
! When compared to the control UV-PUD, enhanced surface scratch resistance, flexibility, yellowing upon QUV exposure, and abrasion resistance are noted for the UV-PUDs studied.
! The UV-PUD oligomers show excellent water resistance. For example, no whitening of any of the cured films was noted after surface exposure to hot water.
! The QUV accelerated weathering results for the UV-PUD oligomers are excellent. These materials have comparable weathering resistance to those of an aliphatic urethane.
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