Dual Cure UV Sealer Review


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Dual Cure UV Sealer Review

  1. 1. Dual Cure UV Sealer Review
  2. 2. DynaSeal ™ Sealer What is it? <ul><li>UV / Thermal Sealer for SMC </li></ul><ul><li>UV portion of cure seals SMC surface before it is exposed to elevated temperatures </li></ul><ul><li>Seals SMC surface to reduce paintability problems </li></ul><ul><ul><li>Porosity </li></ul></ul><ul><ul><li>Outgassing </li></ul></ul><ul><ul><li>Popping </li></ul></ul><ul><li>Improves first-run output at both part manufacturer and auto manufacturer </li></ul>
  3. 3. UV / Thermal Sealer for SMC <ul><li>Prevents porosity-induced defects </li></ul><ul><li>Thermal cure follows UV irradiation for final properties </li></ul><ul><li>Conductive & Non-conductive formulations </li></ul><ul><li>Positive Enhancements </li></ul><ul><ul><li>Compliant VOC </li></ul></ul><ul><ul><li>One coat coverage </li></ul></ul><ul><ul><li>Excellent surface appearance </li></ul></ul><ul><ul><li>Increased first run capability </li></ul></ul>
  4. 4. DynaSeal ™ Sealer for SMC <ul><li>Two-component system </li></ul><ul><li>Solution to porosity on SMC </li></ul><ul><ul><li>Initial sealing properties provided by the low temperature UV film formation </li></ul></ul><ul><ul><li>Ultimate performance provided by the final thermal cure </li></ul></ul><ul><ul><li>Without UV cure parts would still pass all automotive specifications </li></ul></ul>
  5. 5. DynaSeal ™ Sealer Dual Cure Process Unconverted Liquid Film Radiant UV Energy Activated Complexes Initiate Free radical Polymerization Polymerization Produces an Interim Cured Film Thermal Process Produces a Final Cured Film and Ultimate Performance Heat
  6. 6. Advantages of UV / Thermal Approach <ul><li>No need to mask or shield areas that get overspray </li></ul><ul><li>Over spray will cure with a hybrid system </li></ul><ul><li>Field Performance is still achieved without UV Cure </li></ul><ul><li>Coating will accept other coating layers after cure </li></ul><ul><li>UV light to seal porosity can be directed at critical areas only </li></ul>
  7. 7. Composite Materials <ul><li>Recent advancements in SMC & Sealers make usage more attractive. </li></ul><ul><li>Upgraded materials make SMC more cost effective. </li></ul><ul><li>Improved First Run Capabilities justify material & equipment expenses. </li></ul><ul><li>UV Sealers with improved SMC can exploit full potential of SMC usage on cars and trucks. </li></ul><ul><li>New Flexible DynaSeal (UV Sealer) further enhances performance. </li></ul>
  8. 8. Hybrid UV Sealer Process
  9. 9. Performance Comparison DynaSeal™ Sealer vs. In-Mold Coating P225 Panel Comparison
  10. 10. DynaSeal ™ Sealer UV / Thermal Sealer for SMC History & Future <ul><li>Status: </li></ul><ul><ul><li>ITW Ransburg trials Toledo Ohio summer and fall of 2000 </li></ul></ul><ul><ul><li>First customer: Meridian (Kansas City) </li></ul></ul><ul><ul><li>First production trials at Ford KC February 2001 </li></ul></ul><ul><ul><li>Ford KC plant launch September 2001 - P225 box side outers supplied to Ford plant with UV sealer (over 1100 trucks per day – 2200 parts per day) </li></ul></ul><ul><ul><ul><li>Over 400,000 Ford F150 pickup truck on the road with DynaSeal™ </li></ul></ul></ul><ul><ul><ul><li>Over 40,000 Ford Lincoln Aviator (80,000) Fenders for Ford St. Louis </li></ul></ul></ul><ul><ul><ul><li>Successful trials with other automotive parts </li></ul></ul></ul><ul><ul><li>Approvals at other customers complete </li></ul></ul>
  11. 11. Current Production Parts With DynaSeal ™ Aviator F150 Super Crew
  12. 12. DynaSeal ™ FX – New Improved - Flexible <ul><li>SMC popping generated by microscopic porosity plus Pre & Post Stressing of Parts </li></ul><ul><li>DynaSeal Effective for pre-stressing </li></ul><ul><ul><li>Cracks or porosity from molding handling prior to sealer </li></ul></ul><ul><ul><li>Sealer elongation 2-3% </li></ul></ul><ul><li>DynaSeal Flexible Effective for both Pre & Post stressing </li></ul><ul><ul><li>Post stressing occurring from handling after sealer application </li></ul></ul><ul><ul><li>Sealer elongation 20% </li></ul></ul>
  13. 13. DynaSeal ™ Crack in SMC & Post Crack
  14. 14. SMC Crack at Knit line
  15. 15. Porosity of panels stressed prior to Sealer application
  16. 16. Porosity of panels stressed after Sealer application
  17. 17. Elongation Versus Film Build
  18. 18. Rigid vs. Flexible Sealer Rigid Flexible
  19. 19. Following the Photoinitiator Decay
  20. 20. **This matches the published spectra of Lucirin ® TPO-L which makes up 90% of the PI package
  21. 21. Understanding standard curing conditions: Photoinitiator is 100% consumed under standard curing conditions
  22. 23. Understanding the Kinetics of PI Decay
  23. 25. ln[A] = -k(dose) + ln[A] 0 Integrated form for first-order kinetics PI decay is first order
  24. 26. Photoinitiator / Post Cure Conclusions <ul><li>At a nominal cure of 3 J/cm^2, the photoinitiator is 99.7% decomposed. </li></ul><ul><li>There is little or no photoinitiator left after cure to impact UV transmittance or to impart any post reaction. </li></ul><ul><li>Reaction of photoinitiator with UV light is a first order reaction with respect to light energy (number of photons) </li></ul>
  25. 27. Bake/Dosage Window Definition <ul><li>How do Lamp Type, Irradiance Level, and Time impact the cure window? What failure modes would we expect with under or over exposure? </li></ul>
  26. 28. UV Dosage Window Target = 3.0 J/cm 2 ; Range = 2.5 to 6.0 J/cm 2 Dosimeter = EIT Power Puck (UVA + UVB); Bulb = H or D type 10 20 30 40 50 60 70 80 90 Bake Time, minutes 200 225 250 400 275 Part Temperature, °F BAKE LATITUDE 9984805 P35LINE - DynaSeal™ Hybrid UV Sealer 425 Overbake Region Possible Substrate Degradation Optimum Performance Region Sealer Film Build = 1.0 - 1.2 mils 350 300 175 375 325 Underbake Region Possible Performance Loss Target Bake 20 min@260°F Test Criteria: Gravelometer Initial Adhesion Humidity & Adhesion Conductivity Fuel Resistance Porosity Moisture Cold Cycle Florida & WOM
  27. 29. Irradiance Profile for UV Cure
  28. 30. Dosage Variations for Dual Cure Clearcoat
  29. 31. % C=C Cure for Dual Cure Clearcoat versus Dosage
  30. 32. UV Dosage Window <ul><li>With high intensity lights, the cure mechanism depends on total UV dosage (J/cm 2 ) only </li></ul><ul><li>Peak Irradiance level (.5 to 2.8 W/cm 2 ), time/line speed (6 to 50 ft/sec.) and number of passes can be varied without the cure’s dependence on total dosage changing. </li></ul>
  31. 33. Oxygen Inhibition <ul><li>With high intensity lights radical are formed faster than oxygen can scavenge them. </li></ul><ul><li>DynaSeal uses higher molecular weight constituents than a typical 100% UV cure system. </li></ul><ul><li>This combined with the fact that 98% of the solvent has been flashed out means that oxygen diffusion into the film is very slow into the high viscosity (tacky) film that remains. </li></ul>
  32. 34. UV Cure Mechanism <ul><li>Initiation </li></ul><ul><ul><li>PI + UV  PI* </li></ul></ul><ul><ul><li>PI*  R • </li></ul></ul><ul><ul><li>R • + C=C  R-C-C • </li></ul></ul><ul><li>Propagation </li></ul><ul><ul><li>R-C-C • + C=C  R-C-C-C-C • </li></ul></ul><ul><li>Termination </li></ul><ul><ul><li>R• + R•  R-R </li></ul></ul><ul><ul><li>R• + O 2 + P  R-O-O-P </li></ul></ul>
  33. 35. Acrylate Cure at Top of DynaSeal Film
  34. 36. Acrylate Cure at Bottom of DynaSeal Film
  35. 37. Film Properties vs. UV Dosage
  36. 38. Film Properties vs. UV Dosage
  37. 39. UV Cure Window <ul><li>We know that UV from sunlight contributes to the degradation and eventual failure of coatings in the field. Can prolonged exposure to UV lamps during the cure process initiate some of the same type of chemical bond breakages that eventually take place in the field? </li></ul>
  38. 40. Overlay of Sunlight, WOM and H-Bulb Spectra
  39. 41. Photo-oxidation of DynaSeal Primer with UV Cure Dosage
  40. 42. Short Time WOM Exposure of DynaSeal Photo-oxidation
  41. 43. Photo-oxidation of Clearcoats
  42. 44. UV Cure Window <ul><li>Photo-oxidation does occur, but to a very limited extent </li></ul><ul><ul><li>Equivalent to about 2.7 hrs of WOM exposure </li></ul></ul><ul><ul><li>Not enough to cause significant polymer degradation </li></ul></ul><ul><li>There is no observed failures with over exposure of UV up to 12 J/cm^2 </li></ul><ul><li>Porosity will fail at less than 0.5-0.8 J/cm^2. Other Physical properties will pass. </li></ul><ul><li>UV Dosage Target and specification window provides a very robust process with a wide dosage range with no change in chemistry and physical properties. </li></ul><ul><li>The Bake Window chart is applicable to all UV dosages in the specified range </li></ul>
  43. 45. UV Absorbance/Transmittance Questions <ul><li>Does Dynaseal meet durability requirements in the absence of primer/surfacers? </li></ul>
  44. 46. UV Transmission Spectrum of P35AM758
  45. 47. UV Transmission Spectrum of P35AM758
  46. 48. WOM Exposure – SMC with DynaSeal, with and without Primer Surfacer
  47. 49. WOM Exposure – Ecoat, DynaSeal, and Control SMC primer w/out Primer Surfacer
  48. 50. Durability Conclusions <ul><li>Light can be transmitted through sealer film </li></ul><ul><li>Weak Film and Thin film Exposure data show that SMC with Sealer is at least as durable as SMC primer or primer surfacer and considerably better than E-coat </li></ul><ul><li>With other substrates like RIM or carbon fiber there may be issues with exposure with thin or weak film topcoats. </li></ul><ul><li>In general a minimum transmittance specification should be maintained for the topcoats </li></ul>
  49. 51. Summary <ul><li>Dual Cure (UV + Thermal) sealer provides a path to eliminate porosity-induced defects such as paint popping </li></ul><ul><li>Two years production experience on 3D car parts </li></ul><ul><li>Flexible version developed and trialed to eliminate defects from post-sealer stress cracking </li></ul><ul><li>Laboratory data provide a scientific knowledge base for: </li></ul><ul><ul><li>Dosage / Line speed recommendations </li></ul></ul><ul><ul><li>Cure window recommendations </li></ul></ul><ul><ul><li>Equipment choice </li></ul></ul><ul><ul><li>Durability characterization </li></ul></ul>