Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Effects of Painting on
Mechanical Properties of
Injection Molded Plastics
David E. Palmer, P.E.
BRP – Marine Propulsion Sy...
Materials and coatings
QUESTION: Why apply a coating to a material?
2
Appearance
Abrasion/wear
Friction coefficient
Therma...
Materials and coatings
3
QUESTION: Why apply a coating to a material?
ANSWER:
To change the material’s
properties and/or b...
Materials and coatings
4
… is it reasonable to assume
that all other aspects will
remain unchanged?
QUESTION: If we change...
Materials and coatings
5
Effect of nickel plating on fatigue life of steel
Source:
J.O. Almen, "Fatigue, loss
and gain by
...
Materials and coatings
6
Effect of zinc-plated nut on glass-filled nylon-6,6
EDS of corrosion product
on surface of nut
7
Paint and
plastics
Paint and plastics
8
QUESTION: Why paint plastics?
Mass customization
Color/effect not available in resin
Resin lacks UV r...
Paint and plastics
9
QUESTION: What are the effects of painting on
the mechanical properties of plastics?
•Mechanical inte...
Mechanical interactions
• Elastic mismatch
• Interfacial strength
• Film thickness
10
Source:
M.S. Hu and A.G. Evans,
"The...
Chemical interactions
11
• Swelling
• Dissolution
• Environmental stress cracking
Thermal effects
12
• Accelerated solvent diffusion into substrate
• Relief of molded-in stresses
• Shrinkage of paint (ind...
Experimental
13
Experimental design
• For four (4) different substrates, measure
mechanical properties in each of these six (6)
conditions...
Substrates
15
• General purpose ABS
• High impact ABS
• Weather-resistant ASA
• 10% mineral filled polyethylene
ionomer/PA...
Coatings
16
• High-solids black acrylic topcoat
• Clear adhesion promoter (40%
aromatic hydrocarbons)
• Black adhesion pro...
Sample preparation
• Black topcoat:
45 µm dry film build
Cure at 93°C for 20 minutes
• Clear adhesion promoter:
5 µm dry f...
Testing
18
• Notched Izod impact
ASTM D256-10 Method A
• Tension testing
ASTM D638-10
Polyethylene ionomer/PA-6 blend: 50 ...
19
Results
Notched Izod impact
20
Tensile modulus
21
Tensile strength
22
Strain at yield
23
Strain at break
24
Supression of necking
25
High impact ABS
Black adhesion
promoter and
topcoat
High impact ABS
Uncoated
This effect was obse...
Film cracking
26
This effect was
observed in all of
the ABS and ASA
specimens with
topcoat (regardless
of whether or not
t...
Loss of adhesion
27
This effect was observed
the PE ionomer/PA-6
specimens with topcoat
(regardless of whether or
not they...
Film adhesion
28
For the PE ionomer/PA-6 specimens with either
adhesion promoter (without topcoat), no loss of
adhesion wa...
29
Conclusions
Conclusions
30
Rank ordering of effects:
Strain at break
Impact strength
Tensile modulus
Tensile strength
Strain at yield
...
Conclusions
31
Coating effect on substrates:
For ABS and ASA substrates, strain at break
and impact strength decreased wit...
Conclusions
32
Effects of adhesion promoters/topcoat:
The effects of the topcoat and the two adhesion
promoters were diffe...
Conclusion
33
Matching a paint system to a plastic substrate
should be done with great care.
Published data is scarce.
Tes...
Acknowledgements
34
PolyOne – Richard Baril
SABIC – Dennis Yon
LTL Color Compounders – Don Hone
PPG Industries – Ron Kalsk...
Upcoming SlideShare
Loading in …5
×

Effect of Painting on the Mechanical Properties of Injection-Molded Plastics

Paint can have significant effects on the mechanical properties of plastic substrates. The selection of a paint system that is not properly matched to a given plastic substrate can lead to premature failure. While anecdotal accounts are plentiful, quantitative data regarding effects of coating on plastics is relatively scarce. This paper describes the effect of a high-solids acrylic topcoat paint, with either of two different adhesion promoters or no adhesion promoter, on the mechanical properties of four different plastic substrates: general-purpose acrylonitrile-butadiene-styrene (ABS), high-impact ABS, weather-resistant acrylonitrile-styrene-acrylate (ASA), and mineral-filled polyethylene ionomer/polyamide-6 blend.

  • Login to see the comments

Effect of Painting on the Mechanical Properties of Injection-Molded Plastics

  1. 1. Effects of Painting on Mechanical Properties of Injection Molded Plastics David E. Palmer, P.E. BRP – Marine Propulsion Systems Division, Sturtevant, WI
  2. 2. Materials and coatings QUESTION: Why apply a coating to a material? 2 Appearance Abrasion/wear Friction coefficient Thermal barrier Electrical conductivity Corrosion resistance Chemical resistance UV resistance Static dissipation Optical reflectivity
  3. 3. Materials and coatings 3 QUESTION: Why apply a coating to a material? ANSWER: To change the material’s properties and/or behavior
  4. 4. Materials and coatings 4 … is it reasonable to assume that all other aspects will remain unchanged? QUESTION: If we change one aspect of a materials’ properties or behavior…
  5. 5. Materials and coatings 5 Effect of nickel plating on fatigue life of steel Source: J.O. Almen, "Fatigue, loss and gain by electroplating," Product Engineering 22:109-116, June 1951.
  6. 6. Materials and coatings 6 Effect of zinc-plated nut on glass-filled nylon-6,6 EDS of corrosion product on surface of nut
  7. 7. 7 Paint and plastics
  8. 8. Paint and plastics 8 QUESTION: Why paint plastics? Mass customization Color/effect not available in resin Resin lacks UV resistance Aftermarket refinishing Touchup/repair
  9. 9. Paint and plastics 9 QUESTION: What are the effects of painting on the mechanical properties of plastics? •Mechanical interactions •Chemical interactions •Thermal effects
  10. 10. Mechanical interactions • Elastic mismatch • Interfacial strength • Film thickness 10 Source: M.S. Hu and A.G. Evans, "The cracking and decohesion of thin films on ductile substrates," Acta Metallurgica 37:917-925, 1989.
  11. 11. Chemical interactions 11 • Swelling • Dissolution • Environmental stress cracking
  12. 12. Thermal effects 12 • Accelerated solvent diffusion into substrate • Relief of molded-in stresses • Shrinkage of paint (induces residual stresses) • Thermal degradation of substrate
  13. 13. Experimental 13
  14. 14. Experimental design • For four (4) different substrates, measure mechanical properties in each of these six (6) conditions: 14 No coating Adhesion promoter 1 only Adhesion promoter 2 only Topcoat only Adhesion promoter 1 with topcoat Adhesion promoter 2 with topcoat
  15. 15. Substrates 15 • General purpose ABS • High impact ABS • Weather-resistant ASA • 10% mineral filled polyethylene ionomer/PA-6 blend
  16. 16. Coatings 16 • High-solids black acrylic topcoat • Clear adhesion promoter (40% aromatic hydrocarbons) • Black adhesion promoter (<2% aromatic hydrocarbons)
  17. 17. Sample preparation • Black topcoat: 45 µm dry film build Cure at 93°C for 20 minutes • Clear adhesion promoter: 5 µm dry film build Cure at 77°C for 20 minutes • Black adhesion promoter: 20 µm dry film build Cure at 71°C for 20 minutes 17
  18. 18. Testing 18 • Notched Izod impact ASTM D256-10 Method A • Tension testing ASTM D638-10 Polyethylene ionomer/PA-6 blend: 50 mm/min All other substrates: 5 mm/min
  19. 19. 19 Results
  20. 20. Notched Izod impact 20
  21. 21. Tensile modulus 21
  22. 22. Tensile strength 22
  23. 23. Strain at yield 23
  24. 24. Strain at break 24
  25. 25. Supression of necking 25 High impact ABS Black adhesion promoter and topcoat High impact ABS Uncoated This effect was observed in all of the coated ABS and ASA specimens.
  26. 26. Film cracking 26 This effect was observed in all of the ABS and ASA specimens with topcoat (regardless of whether or not they had adhesion promoter).
  27. 27. Loss of adhesion 27 This effect was observed the PE ionomer/PA-6 specimens with topcoat (regardless of whether or not they had adhesion promoter).
  28. 28. Film adhesion 28 For the PE ionomer/PA-6 specimens with either adhesion promoter (without topcoat), no loss of adhesion was observed. The specimen above experienced 165% elongation at break.
  29. 29. 29 Conclusions
  30. 30. Conclusions 30 Rank ordering of effects: Strain at break Impact strength Tensile modulus Tensile strength Strain at yield Largest effects Little/no effect
  31. 31. Conclusions 31 Coating effect on substrates: For ABS and ASA substrates, strain at break and impact strength decreased with coating. For mineral-filled PE ionomer/PA-6 blend, strain at break and impact strength increased with coating.
  32. 32. Conclusions 32 Effects of adhesion promoters/topcoat: The effects of the topcoat and the two adhesion promoters were different on different substrates. When the adhesion promoters were used together with the topcoat, the effects were not additive.
  33. 33. Conclusion 33 Matching a paint system to a plastic substrate should be done with great care. Published data is scarce. Testing is the best way to ensure a successful match.
  34. 34. Acknowledgements 34 PolyOne – Richard Baril SABIC – Dennis Yon LTL Color Compounders – Don Hone PPG Industries – Ron Kalski, Dave Nale, Cari Stein Polymer Diagnostics – Keith Mathews, Jill Moran, Katlyn Hoffman BRP US, Inc. – Bill Barth, Rich Smock, Mike Davenport, Ben Jones, Matt Coyne

×