SUNLIGHT CURABLE COATING COMPOSITIONS

• US 20150284589A1
• Filed: 04/08/2014
• Published: 10/08/2015
• Est. Priority Date: 04/08/2014
• Status: Active Grant

• Current Assignee: Dymax Corporation (Becton, Dickinson & Co)
• Original Assignee: Dymax Corporation (Becton, Dickinson & Co)
• Inventors: Cayer, Christopher Alan, Nebioglu, Ahmet, Aerykssen, James
• Granted Patent: US 9,340,704 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61P 31/12 Antivirals
• CPC Class Codes: B05D 3/067 Curing or cross-linking the coating
• CPC Class Codes: C08G 18/3206 aliphatic
• CPC Class Codes: C08G 18/3228 acyclic
• CPC Class Codes: C08G 18/40 High-molecular-weight compounds C08G18/2805 takes precedence
• CPC Class Codes: C08G 18/672 Esters of acrylic or alkyl acrylic acid having only one group containing active hydrogen
• CPC Class Codes: C08G 18/673 containing two or more acrylate or alkylacrylate ester groups
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds

Abstract

A coating composition capable of curing to a high hardness by exposure to sunlight. More particularly, the coating composition comprises a high molecular weight polyurethane (meth)acrylate or methacrylate dissolved in one or more non-alcohol solvent, a visible light photoinitiator, and an alcohol solubilizer.

Claims

1. A liquid, curable coating composition comprising in admixture:

(a) one or more polyurethane film-forming polymers having the formula

C-(D-[-(R-D)_n-(P-D)_m-]_xE)_k-C

wherein;

i) D is a diisocyanate group,

ii) R is one or more diol or triol groups having a molecular weight less than or equal to 500 Daltons;

iii) P is one or more oligomeric diol groups having a molecular weight of from about 500 Daltons to about 3000 Daltons;

iv) E is a urea group having a molecular weight less than or equal to 500 Daltons;

v) C is a monohydroxyl functional acrylate group or methacrylate group;

wherein the equivalent ratio of equivalent ratio of (i) to (ii) is less than 1.5;

1; and

the equivalent ratio of (i) to (iii) is greater than 15;

1;

n=20 to 450, m=0 to 5, x=1 to 10, and k=1 to 10;

b) an alcohol solubilizer;

c) a non-alcohol solvent;

(d) a photoinitiator in an amount sufficient to polymerize the polyurethane film-forming polymers when exposed to light energy having a wavelength of 395 nm or above at an energy level of about 1 J/cm² or more.

2. The coating composition according to claim 1 wherein the amount of polyurethane film-forming polymer is from about 15% to about 50% based on the weight of the coating composition.

3. The coating composition according to claim 1 wherein the diisocyanate comprises a residue of one or more of hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, bis(4-isocyanatocyclohexyl)methane, isophorone diisoycanate, tetramethylxylene diisocyanate, trimethylhexamethylene diisocyanate, toluene diisocyanate, and isophorone diisoycanate.

4. The coating composition according to claim 1 wherein the diol or triol has a molecular weight of about 500 g/mole or less.

5. The coating composition according to claim 1 wherein the oligomeric diol has a molecular weight of from about 1000 Daltons to about 2000 Daltons.

6. The coating composition according to claim 1 wherein the urea group is formed by reaction of ethylenediamine or water with the diisocyanate group (D).

7. The coating composition according to claim 1 wherein the urea group is present in an amount of less than about 0.8% based on the weight of the polyurethane film-forming polymer.

8. The coating composition according to claim 1 wherein the acrylate group or methacrylate group comprises a residue of one or more of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate. N-(2-Hydroxypropyl)methacrylamide and pentaerythritol triacrylate.

9. The coating composition according to claim 1 wherein the polyurethane polymers have a molecular weight of about 100,000 Daltons or less.

10. The coating composition according to claim 1 wherein the polyurethane polymers have a Tg of about 0°

C. or greater.

11. The coating composition according to claim 1 wherein the polyurethane polymers have a melting point of about 50°

C. or greater.

12. The coating composition according to claim 1 wherein the non-alcohol solvent is organic and has a flash point lower than about 80°

C.

13. The coating composition according to claim 1 wherein the non-alcohol solvent is present in an amount of about 20% or more based on the weight of the coating composition.

14. The coating composition according to claim 1 wherein the alcohol solubilizer as a molecular weight of about 500 g/mole or less.

15. The coating composition according to claim 1 wherein the photoinitiator comprises one or more of methanone, 1,1′

-(phenylphosphinylidene)bis[1-(2,4,6-trimethylphenyl)-, methanone, (diphenylphosphinyl)(2,4,6-trimethylphenyl)-, phosphinic acid, P-phenyl-P-(2,4,6-trimethylbenzoyl)-, ethyl ester, and bicyclo[2.2.1]heptane-2,3-dione, 1,7,7-trimethyl-, and camphorquinone.

16. The coating composition according to claim 1 wherein the photoinitiator is present in an amount of from about 0.1% to about 10% by weight based on the weight of the coating composition.

17. The coating composition according to claim 1 additionally comprising one or more components selected from the group consisting of film forming polymers, defoamers, pigments and adhesion promoters.

18. A method of forming a substantially tack-free coating which comprises:

I) forming a liquid, curable coating composition comprising in admixture;

(a) one or more polyurethane film-forming polymers having the formula

C-(D-[-(R-D)_n-(P-D)_m-]_xE)_k-C

wherein;

i) D is a diisocyanate group,

ii) R is one or more diol or triol groups having a molecular weight less than or equal to 500 Daltons;

iii) P is one or more oligomeric diol groups having a molecular weight of from about 500 Daltons to about 3000 Daltons;

iv) E is a urea group having a molecular weight less than or equal to 500 Daltons;

v) C is a monohydroxyl functional acrylate group or methacrylate group;

wherein the equivalent ratio of equivalent ratio of (i) to (ii) is less than 1.5;

1; and

the equivalent ratio of (i) to (iii) is greater than 15;

1;

n=20 to 450, m=0 to 5, x=1 to 10, and k=1 to 10;

b) an alcohol solubilizer;

c) a non-alcohol solvent;

(d) a photoinitiator in an amount sufficient to polymerize the polyurethane film-forming polymers when exposed to light energy having a wavelength of 395 nm or above at an energy level of about 1 J/cm² or more;

II) applying the coating composition onto a substrate following by evaporating the non-alcohol solvent and alcohol solubilizer to form substantially tack-free coating;

III) exposing the composition resulting from step II) to light energy having a wavelength of 395 nm or above at an energy level of about 1 J/cm² or more.

19. The method according to claim 18 wherein the substantially tack-free coating formed after evaporation of non-alcohol solvent and alcohol solubilizer has a pencil hardness of about 2 B or less as measured according to ASTM D3363.

20. The method according to claim 18 wherein the coating resulting from step III) has a pencil hardness of about 2H or more as measured according to ASTM D3363.