Sunlight curable coating compositions

• US 9,340,704 B2
• Filed: 04/08/2014
• Issued: 05/17/2016
• 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, Aerykssen, James, Nebioglu, Ahmet
• Primary Examiner(s): Leonard, Michael L
• Application Number:
  US14/248,280
• Publication Number:
  US 20150284589A1
• Time in Patent Office: 770 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 residue of a diisocyanate group,

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

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

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

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

wherein the 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=θ

1 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 residue of the diisocyanate group 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 residue of the diol or triol group has a molecular weight of about 500 g/mole or less.

5. The coating composition according to claim 1, wherein the residue of 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 residue of 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 residue of 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 residue of 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 residue of a diisocyanate group,

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

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

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

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

wherein the 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=θ

1 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 2B 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.