METHOD FOR FORMING SOFT TOUCH COATINGS

Abstract

Soft feel coatings having improved haptic qualities are obtained by curing a coating composition containing at least one radiation-curable compound, at least one photoinitiator, at least one surface conditioner additive selected from the group consisting of particulate surface modification agents slip additives using a multistage curing procedure, involving exposing the coating composition to a long wavelength ultraviolet radiation source and then a short wavelength ultraviolet radiation source.

Claims

1. A method for forming a soft touch coating on a surface of a substrate, comprising in succession the steps of: a) applying a layer of a coating composition, comprised of at least one radiation-curable compound, at least one surface conditioner additive selected from the group consisting of slip additives and particulate surface modification agents and at least one photoinitiator, to at least a portion of the surface of the substrate; b) exposing the layer of the coating composition to long wavelength ultraviolet radiation; and c) exposing the layer of the coating composition to short wavelength ultraviolet radiation.

2. The method of claim 1, wherein the at least one surface conditioner additive comprises at least one slip additive selected from the group consisting of polysiloxanes, natural and synthetic waxes and fluoropolymers, wherein the slip additive may optionally comprise at least one radiation-curable double bond.

3. The method of claim 1, wherein the at least one surface conditioner additive comprises at least one polysiloxane selected from the group consisting of silicone polyether copolymers and silicone acrylates.

4. The method of claim 1, wherein the coating composition is comprised of from 0.2 to 20 percent by weight slip additive.

5. The method of any of claim 1, wherein the at least one radiation-curable compound comprises at least one (meth)acrylate-functionalized monomer or oligomer selected from the group consisting of (meth)acrylate esters of aliphatic mono-alcohols, (meth)acrylate esters of alkoxylated aliphatic mono-alcohols, (meth)acrylate esters of aliphatic polyols, (meth)acrylate esters of alkoxylated aliphatic polyols, (meth)acrylate esters of aromatic alcohols, (meth)acrylate esters of alkoxylated aromatic alcohols, epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates and amine- and sulfide-modified derivatives thereof and combinations thereof.

6. The method of claim 1, wherein the coating composition is comprised of 50 to 99 percent by weight in total of radiation-curable compound.

7. The method of claim 1, wherein the at least one surface conditioner additive comprises at least one particulate surface modification agent selected from the group consisting of silicas, polymer beads and wax particles.

8. The method of claim 1, wherein the coating composition is comprised of from 0.2 to 30 percent by weight particulate surface modification agent.

9. The method of claim 1, wherein the coating composition comprises at least one slip additive and at least one particulate surface modification agent.

10. The method of claim 1, wherein the coating composition comprises at least one slip additive and at least one silica as a particulate surface modification agent.

11. The method of claim 1, wherein the coating composition comprises at least one polysiloxane as a slip additive and at least one silica as a particulate surface modification agent.

12. The method of claim 1, wherein the at least one photoinitiator comprises at least one photoinitiator selected from the group consisting of alpha-hydroxy ketones, phenylglyoxylates, benzyldimethylketals, alpha-aminoketones, mono-acyl phosphines, bis-acyl phosphines, metallocenes, phosphine oxides, benzoin ethers and benzophenones and combinations thereof.

13. The method of claim 1, wherein the coating composition comprises a single photoinitiator which is capable of absorption of both short wavelength ultraviolet radiation and long wavelength ultraviolet radiation.

14. The method of claim 13, wherein the single photoinitiator is selected from the group consisting of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzyl dimethyl ketal and 1-hydroxycyclohexylphenyl ketone.

15. The method of claim 1, wherein the coating composition is comprised of from 0.1 to 10 percent by weight photoinitiator.

16. The method of claim 1, wherein the coating composition is comprised of a first photoinitiator which is capable of absorption of short wavelength ultraviolet radiation and a second photoinitiator which is capable of absorption of long wavelength ultraviolet radiation.

17. The method of claim 1, wherein the coating composition is comprised of not more than 1% by weight in total of non-reactive solvent and water.

18. The method of claim 1, wherein the substrate is comprised of a material selected from the group consisting of thermoplastics, thermoset resins, ceramics, cellulosic materials, leather and metals.

19. The method of claim 1, wherein the long wavelength UV light is supplied by one or more lamps selected from the group consisting of D bulb mercury lamps, V bulb mercury lamps and LED lamps.

20. The method of claim 1, wherein the long wavelength UV light has a wavelength of from 300 to 420 nm or 320 to 400 nm.

21. The method of claim 1, wherein the short wavelength UV light is supplied by one or more lamps selected from the group consisting of mercury arc lamps and H bulb lamps.

22. The method of claim 1, wherein the short wavelength UV light has a wavelength of from 220 to 280 nm or 230 to 270 nm.

23. The method of claim 1, wherein the layer of the coating composition has a thickness of from 4 to 200 microns or from 10 to 75 microns.

24. A substrate having a soft touch coating obtained by the method of claim 1.

Description

EXAMPLES

Examples 1, 1B and 2

[0090] Three different coating compositions were prepared, in accordance with the following formulations (Tables 1-3). The silica used in these formulations as a particulate surface modification agent was a polymer-treated thermal silica (also characterized as a polysiloxane-coated fumed silica).

Example 1

[0091]

TABLE-US-00001 TABLE 1 (Example 1) Component Mass (g) Weight % Diacrylate-functionalized 24.00 52.46 Polytetramethylene Ether (M.sub.n = ca. 650 g/mol) Propoxylated Neopentyl 16.00 34.97 Glycol Diacrylate Dispersant (structured acrylic 0.35 0.77 copolymer) Silica 3.40 7.43 2-Hydroxy-2-methyl-1- 2.00 4.37 phenyl-1-propanone Total 45.75 100.00

Example 1B

[0092]

TABLE-US-00002 TABLE 2 (Example 1B) Component Mass (g) Weight % Diacrylate-functionalized 24.00 51.68 Polytetramethylene Ether (M.sub.n = ca. 650 g/mol) Propoxylated Neopentyl 16.00 34.45 Glycol Diacrylate Dispersant (structured acrylic 0.35 0.76 copolymer) Silica 3.40 7.32 2-Hydroxy-2-methyl-1- 2.00 4.31 phenyl-1-propanone Slip Additive (Polyether 0.69 1.48 Siloxane Copolymer) Total 46.44 100.00

Example 2

[0093]

TABLE-US-00003 TABLE 3 (Example 2) Component Mass (g) Weight % Diacrylate-functionalized 39.00 51.22 Polytetramethylene Ether (M.sub.n = ca. 650 g/mol) Propoxylated Neopentyl Glycol 26.00 34.15 Diacrylate Dispersant (structured acrylic 0.57 0.75 copolymer) Silica 5.53 7.26 Diphenyl(2,4,6- 1.95 2.56 trimethylbenzoyl)phosphine oxide 70:30 (w/w) Blend of Oligo[2- 1.95 2.56 hydroxy-2-methyl-1-[4-(1- methylvinyl)phenyl]propanone] and 2-Hydroxy-2-methyl-1- phenyl-1-propanone Slip Additive (Polyether 1.14 1.50 Siloxane Copolymer) Total 76.14 100.00

[0094] The aforementioned formulations were drawn down on substrates as 1 mil thickness coatings and photocured using different conditions, as summarized in the following Table 4. The results obtained for the cured coatings are also described in the table.

TABLE-US-00004 TABLE 4 Formulation Example Cure Conditions Feel Gloss 1 2 Mercury arc Not Soft 31.7 lamps, 400 W/in, 50 fpm 1B 2 Mercury arc Not Soft 33.9 lamps, 400 W/in, 50 fpm 2 V lamp 600 W/in + Velvety 10.4 2 passes under 2 Mercury arc lamps, 50 fpm 2 V lamp 400 W/in + Velvety 8.8 2 passes under 2 Mercury arc lamps, 50 fpm 2 395 nm LED Velvety 8.2 12 W/in + 2 passes under 2 Mercury arc lamps, 50 fpm 2 395 nm LED 6 W/in + Velvety 5.9 2 passes under 2 Mercury arc lamps, 50 fpm

Example 3

[0095] The following formulation (Table 5) was prepared as a coating composition. The silica used in this formulation as a particulate surface modification agent was a polymer-treated thermal silica (also characterized as a polysiloxane-coated fumed silica).

TABLE-US-00005 TABLE 5 (Example 3) Component Mass (g) Weight % Acrylate Oligomer (Isocyanurate 15.76 47.44 Derivative) Lauryl Acrylate 7.88 23.72 Propoxylated Neopentyl Glycol 5.25 15.81 Diacrylate Dispersant (structured acrylic 0.22 0.67 copolymer) Silica 2.17 6.52 Diphenyl(2,4,6- 1.44 4.35 trimethylbenzoyl)phosphine oxide Slip Additive (Polyether Siloxane 0.49 1.48 Copolymer) Total 33.22 100.00

[0096] The coating composition of Example was drawn down to a thickness of 3 mil on a substrate and photocured using the conditions shown in Table 6.

TABLE-US-00006 TABLE 6 Formulation Example Cure Conditions Feel Gloss 3 2 Mercury arc Not Soft 38.2 lamps, 400 W/in, 50 fpm 3 V lamp 600 W/in + Velvety 6.7 H lamp 600 W/in, 50 fpm

Example 4

[0097] A coating composition was prepared based on the following formulation (Table 7). The silica used in this formulation as a particulate surface modification agent was a polymer-treated thermal silica (also characterized as a polysiloxane-coated fumed silica).

TABLE-US-00007 TABLE 7 (Example 4) Component Mass (g) Weight % Diacrylate-functionalized 12.00 50.35 Polytetramethylene Ether (M.sub.n = ca. 650 g/mol) Propoxylated Neopentyl 8.00 33.57 Glycol Diacrylate Dispersant (structured acrylic 0.18 0.74 copolymer) Silica 1.70 7.13 1-Hydroxy-cyclohexyl- 0.90 3.78 phenyl-ketone 2,4,6-Trimethylbenzoyl- 0.30 1.26 diphenyl phosphine oxide Mixture of Benzophenones 0.40 1.68 and Methylbenzophenones Slip Additive (Polyether 0.36 1.50 Siloxane Copolymer) Total 23.83 100.00

Example 5

[0098] A coating composition was prepared based on the following formulation (Table 8). The silica used in this formulation as a particulate surface modification agent was a polymer-treated thermal silica (also characterized as a polysiloxane-coated fumed silica).

TABLE-US-00008 TABLE 8 (Example 5) Component Mass (g) Weight % Diacrylate-functionalized 12.00 51.67 Polytetramethylene Ether (M.sub.n = ca. 650 g/mol) Propoxylated Neopentyl Glycol 8.00 34.45 Diacrylate Dispersant (structured acrylic 0.18 0.76 copolymer) Silica 1.7 7.32 50:50 Blend of 1-Hydroxy- 1 4.31 cyclohexyl-phenyl-ketone and Benzophenone Slip Additive (Polyether 0.35 1.50 Siloxane Copolymer) Total 23.22 100.00

[0099] The coating compositions of Examples 1B, 2 and 4-5 were drawn down to a thickness of 3 mil on a substrate and photocured using the conditions described in the following Table 9.

TABLE-US-00009 TABLE 9 Formulation Example Cure Conditions Feel Gloss 1B V lamp 600 W/in + H Velvety 1.4 lamp 600 W/in, 50 fpm 4 V lamp 600 W/in + H Velvety 3.2 lamp 600 W/in, 50 fpm 2 V lamp 600 W/in + H Velvety/Rubbery 1.4 lamp 600 W/in, 50 fpm 5 V lamp 600 W/in + H Velvety 2.0 lamp 600 W/in, 50 fpm