DUAL CURE SOFT TOUCH COATINGS

Abstract

Coatings having a favorable combination of soft touch characteristics and durability are obtained by dual curing compositions containing free radical-curable ethylenically unsaturated compound(s), polyol(s) and polyisocyanate(s).

Claims

1. A coating composition comprised of at least one free radical-curable ethylenically unsaturated compound, at least one polyol and at least one polyisocyanate.

2. The coating composition of claim 1, wherein the at least one free radical-curable ethylenically unsaturated compound includes at least one compound having one or more functional groups selected from the group consisting of vinyl groups, acrylate groups, methacrylate groups and combinations thereof.

3. The coating composition of claim 1, wherein the at least one free radical-curable ethylenically unsaturated compound includes at least one isocyanurate tri(meth)acrylate or derivative thereof.

4. The coating composition of claim 1, wherein the at least one free radical-curable ethylenically unsaturated compound includes at least one urethane diacrylate.

5. The coating composition of claim 1, wherein the at least one free radical-curable ethylenically unsaturated compound includes at least one isocyanurate tri(meth)acrylate or derivative thereof and at least one urethane diacrylate.

6. The coating composition of claim 1, wherein the at least one ethylenically unsaturated compound includes at least one isocyanate functionality-containing urethane acrylate.

7. The coating composition of claim 1, wherein the at least one free radical-curable ethylenically unsaturated compound includes at least one isocyanate-reactive functionality-containing (meth)acrylate.

8. The coating composition of claim 1, further comprising at least one photoinitiator.

9. The coating composition of claim 1, further comprising at least one free radical initiator that decomposes when heated or in the presence of an accelerator.

10. The coating composition of claim 1, further comprising at least one matting agent.

11. The coating composition of claim 1, further comprising at least one non-reactive solvent.

12. The coating composition of claim 1, wherein the coating composition is free of non-reactive solvent.

13. The coating composition of claim 1, wherein the coating composition is water-borne.

14. The coating composition of claim 1, wherein the at least one polyol includes one or more polyols selected from the group consisting of polyester polyols, polyether polyols, polycarbonate polyols, polycarbonate polyester polyols, polyacrylic polyols, polyurethane polyols, polycaprolactone polyols, polyolefin polyols and combinations thereof.

15. The coating composition of claim 1, wherein the at least one polyisocyanate includes one or more polyisocyanates selected from the group consisting of aromatic polyisocyanates, aliphatic polyisocyanates and cycloaliphatic polyisocyanates.

16. The coating composition of claim 1, wherein the weight ratio of (polyol+polyisocyanate):free radical-curable ethylenically unsaturated compound is from 1:1 to 10:1.

17. The coating composition of claim 1, wherein the coating composition is comprised of at least one polyol, at least one polyisocyanate, at least one non-reactive solvent, at least one urethane diacrylate, at least one isocyanurate tri(meth)acrylate, at least one matting agent and at least one photoinitiator.

18. The coating composition of claim 1, wherein the coating composition is comprised of at least one polyol, at least one polyisocyanate, at least one non-reactive solvent, at least one isocyanate functionality-containing urethane acrylate, at least one matting agent and at least one photoinitiator.

19. The coating composition of claim 1, wherein the said coating composition is packaged in the form of two separate parts as follows: a-1) a Part A-1 comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyisocyanate; and b-1) a Part B-1 comprised of at least one polyol; or a-2) a Part A-2 comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyol; and b-2) a Part B-2 comprised of at least one polyisocyanate.

20. A method of forming a coating on a surface of a substrate, comprising the steps of applying at least one layer of the coating composition of claim 1, to the surface of the substrate, exposing the coating composition to an amount of radiation and/or of heat effective to initiate cure of the at least one free radical-curable ethylenically unsaturated compound and reacting the at least one polyol and the at least one polyisocyanate.

21. The method of claim 20, wherein the coating composition is prepared by mixing a first part comprised of the at least one free radical-curable ethylenically unsaturated compound and the at least one polyol with a second part comprised of the at least one polyisocyanate or by mixing a first part comprised of the at least one polyol and a second part comprised of the at least one polyisocyanate and the at least one free radical-curable ethylenically unsaturated compound.

22. The method of claim 20, wherein the coating composition is heated after being applied to the surface of the substrate.

23. The method of claim 20, wherein the coating composition is heated after exposing the coating composition to the amount of radiation effective to initiate cure of the at least one free-radical curable ethylenically unsaturated compound.

24. The method of claim 20, wherein the coating composition is exposed to the amount of radiation effective to initiate cure of the at least one free-radical curable ethylenically unsaturated compound, after heating the coating composition.

25. A precursor composition useful for forming a coating composition as defined in claim 1, when said precursor composition is combined with at least one polyol, wherein the precursor composition is comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyisocyanate, the said precursor composition being free of any polyol.

26. A precursor composition useful for forming a coating composition as defined in claim 1, when said precursor composition is combined with at least one polyisocyanate, wherein the precursor composition is comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyol, said precursor composition being free of any polyisocyanate.

27. A two part system useful for forming a coating composition as defined according to claim 1, comprising as separately packaged components, either: a-1) a Part A-1 comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyisocyanate; and b-1) a Part B-1 comprised of at least one polyol; or a-2) a Part A-2 comprised of at least one free radical-curable ethylenically unsaturated compound and at least one polyol; and b-2) a Part B-2 comprised of at least one polyisocyanate.

28. A method of making a coating, comprising combining Part A-1 and Part B-1 of claim 27 or combining Part A-2 and Part B-2 of claim 27 to form a coating composition, applying the coating composition to a surface of a substrate and curing the applied coating composition.

29. A coating comprised of at least one layer of a coating composition in accordance with claim 1, wherein the coating composition is cured.

30. An article of manufacture comprised of a substrate, wherein a surface of the substrate is at least partially coated with a coating composition in accordance with claim 1.

31. The article of manufacture of claim 30, wherein the surface of the substrate is comprised of at least one material selected from the group consisting of thermosets, thermoplastics, metals, wood, leather, glass, paper, cardboard and combinations thereof.

32. (canceled)

Description

EXAMPLES

[0119] The Examples using the dual curable compositions described herein report properties related to feel, hardness, adhesion, abrasion resistance and stain resistance. The properties reported for the Examples were determined using a number of known techniques. Pencil hardness (mar resistance) was determined in accordance with ASTM D3363-05. Adhesion was determined in accordance with ASTM D3359-09. Abrasion resistance was determined in accordance with ASTM F2357-10. MEK (solvent) resistance was determined in accordance with ASTM D5402-06. Stain resistance was determined in accordance with ANSI/KCMA A161.1 chemical resistance test with E measurements. Stain resistance was also determined in accordance with General Motors sunscreen and insect repellant resistance test procedures, e.g., GMW14445. With the exception of GMW14445 (performed at 80 C.), the aforementioned tests were performed at room temperature and ambient humidity.

[0120] For each of the Examples, the compositions were applied on substrates with a target thickness of 36 m. The type of substrate used depended upon the particular test(s) being run. ABS panels were used for evaluation of adhesion and feel, glass was used to evaluate abrasion and pencil hardness, metal leneta was used to evaluate stain resistance, and aluminum was used to evaluate MEK resistance. The applied compositions were dual cured using a combination of the two part (polyol+polyisocyanate) urethane reaction and free radical cure. The coated panels were thermally cured, i.e., baked, to accelerate the urethane reaction, while the free radical cure was completed using UV-light. The thermal cure was achieved by heating the samples at 70 C. for 60 minutes. The UV cure was administered using one 600 W/in H-bulb lamp at 50 feet per minute for two passes. The coated ABS panels, after curing, exhibited a soft feel characterized as velvety or rubbery, good adhesion on ABS (66 crosshatch) and good mar and solvent resistance. The coatings of the Examples were compared to commercially available two-part urethane soft feel coatings without free radical-curable (meth)acrylate and were rated by experienced observers with respect to type of feel (rubbery, velvety, silky) and softness (1=no soft feel, 5=best soft feel).

[0121] The compositions of Examples 1-3 are listed below in Table 1, whereby ingredients and respective masses added are provided. Additionally, the weight percentages on total formulation weight for Examples 1-3 are given in Table 2 which includes the solvent incorporated in the two part urethane. Initial testing included the formulations of Examples 1 and 2. Formulation 1 was subsequently altered to produce Example 3 at reduced added free radical-curable (meth)acrylate content. Formulation 2 had reduced two part urethane hardener content, allowing residual hydroxyl content of the two part urethane polyol resin to react with the isocyanate-containing urethane acrylate.

TABLE-US-00003 TABLE 1 Composition by weight for dual curable formulations Product Example 1 Example 2 Example 3 Two part urethane polyol resin 25 g 25 g 25 g (polyester diol) Two part urethane isocyanate 6.30 g 3.15 g 6.3 g hardener (hexamethylene diisocyanate polymer) Urethane diacrylate (CN9782, 4.49 g 0 g 2.60 g product of Sartomer USA, LLC) Triisocyanurate derivative (SR368, 2.99 g 0 g 1.74 g product of Sartomer USA, LLC) Isocyanate functionality containing 0 g 5.31 g 0 g urethane acrylate (CN9302, product of Sartomer USA, LLC) Matting agent (Acematt 3300 0.64 g 0.45 g 0.64 g treated silica) Photoinitiator (1-hydroxy- 0.374 g 0.265 g 0.217 g cyclohexylphenyl-ketone)

TABLE-US-00004 TABLE 2 Composition by weight percent for dual curable formulations Product Example 1 Example 2 Example 3 Two part urethane polyol resin 35.7% 41.5% 38.9% solids (polyester diol) Two part urethane isocyanate 8.0% 4.7% 8.8% hardener solids (hexamethylene diisocyanate polymer) Two part urethane incorporated 34.9% 36.2% 38.1% solvent (mixture of solvents) Urethane diacrylate (CN9782, 11.3% 0.0% 7.1% product of Sartomer USA, LLC) Triisocyanurate derivative (SR368, 7.5% 0.0% 4.8% product of Sartomer USA, LLC) Isocyanate functionality containing 0.0% 15.5% 0.0% urethane acrylate (CN9302, product of Sartomer USA, LLC) Matting agent (Acematt 3300 1.6% 1.3% 1.8% treated silica) Photoinitiator (1-hydroxy- 0.9% 0.8% 0.6% cyclohexylphenyl-ketone)

[0122] A comparative Example is also provided, which is a two-part system comprising multifunctional isocyanate and a difunctional polyol in solvent. The comparative Example employed 87.45 g of ST2010 clear resin (available from The Alsa Corporation) with 22.05 g of ST2010 hardener (also available from The Alsa Corporation). Substrates coated with the two part, curable composition of the comparative Example were prepared in a similar manner to the substrates coated with the dual curable composition of Examples 1-3.

[0123] Table 3 is provided below and includes test results for Examples 1-3 and the comparative Example with respect to certain properties, such as feel, gloss, pencil hardness and adhesion.

TABLE-US-00005 TABLE 3 Film properties of two-part curable formulations and Comparative Example Feel Rank Formulation Feel Type (5 = best) Gloss Pencil Adhesion Comparative Example Velvety 4 2.2 7B 100 Example 1 Rubbery 2 30.9 2B 100 Example 2 Velvety 3 1.6 B 100 Example 3 Velvety 4 1.3 3B 100

[0124] Table 4 is provided below and includes test results for Examples 1-3 and the comparative Example with respect to stain resistance to multiple products and chemical (MEK) resistance.

TABLE-US-00006 TABLE 4 Resistance properties of Examples 1-3 and the Comparative Example Coffee Mustard Ketchup Red Wine MEK Resistance Formulation Stain E Stain E Stain E Stain E (Double Rubs) Comparative 13.80 15.86 8.85 12.80 24 Example Example 1 10.74 14.62 12.18 8.62 79 Example 2 10.74 14.62 12.18 8.62 79 Example 3 5.1 2.64 6.35 23.55 47

[0125] Table 5 is provided below and includes test results for Example 3 and the comparative Example delineating the variation in properties due to the order in which the dual cure is carried out. Additionally, Table 6 demonstrates the cure rating at various points throughout both variations demonstrating less tack with radiation curing first. Cure ratings range from 1-5; 1 signifies an under cured surface that is fully imprinted by cotton tip and lacks mar resistance while 5 signifies a fully cured coating that is not easily imprinted by cotton tip nor easily marred by a wooden scraper.

TABLE-US-00007 TABLE 5 Properties of Example 3 (dual-cured in both possible orders) and the Comparative Example (thermal cure only) Bug Two-Part spray Cure Feel Rank Resis- Formulation Order (5 = best) Persoz Pencil Gloss tance Comparative N/A 4 139 7B 2.2 Fail Example Example 3 UV-Bake 4 74 5B 1.3 Pass Example 3 Bake-UV 4 75 3B 1.3 Pass

TABLE-US-00008 TABLE 6 Cure Rating and Persoz Hardness of Example 3 throughout dual cure process in both UV-bake and bake-UV order Example 3: UV Cure followed Example 3: Bake followed by Bake by UV Cure Cure Step Cure Rating Cure Step Cure Rating UV cure 2 Bake 30 min 1 Bake 15 min 3 Bake 45 min 2 Bake 45 min 3 Bake 1 hr 2 Bake 1 hr 4 UV (2) 5 (final) Persoz: 30 Persoz: 29 Next Day 5 Next Day 5 Persoz: 55 Persoz: 58

[0126] As can be seen from Tables 3-5, the dual curable compositions described herein exhibit increased durability and certain stain resistance properties while retaining the soft feel characteristics of the comparative Example.