Acrylic adhesive composition from protected photocrosslinking agents

Patent metadata

Field	Value
Publication number	US-10189771-B2
Application number	US-201615550830-A
Country	US
Kind code	B2
Filing date	Jan 28, 2016
Priority date	Feb 18, 2015
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

Protected photocrosslinkers and their use in two-stage photocuring of (meth)acrylate monomers is described.

First claim

What is claimed is:

1. A protected photocrosslinker of the formula:

wherein
R 1 is H or CH 3 ;
each of X 1 and X 2 is —O— or —NR 1 —;
R 2 is a divalent (hetero)hydrocarbyl group;
subscript a is 0 or 1;
Prot is a carbonyl protecting group;
R 3 is selected from:

wherein each R 4 is H or a C 1 to C 6 alkyl group, R 5 is independently a hydroxyl group, a phenyl group, a C 1 to C 6 alkyl group, or a C 1 to C 6 alkoxy group.

2. The protected photocrosslinker of claim 1 wherein Prot is a cyclic or acyclic ketal, dithioketals, O-substituted cyanohydrins, substituted hydrazones, oxazolidines, imidazolidines and thiazolidines protecting groups.

3. The protected photocrosslinker of claim 1 where X 1 —R 2 —X 2 is —NH—C(CH 3 ) 2 —CO—O—(R 10 —O) b —, where R 10 is a linear or branched alkylene, and subscript b is 0 or 1.

4. A polymerizable composition comprising a monomer mixture of at least one (meth)acrylate monomer, a photoinitiator and a protected photocrosslinker of claim 1 .

5. The polymerizable composition of claim 4 wherein the monomer mixture comprises:
a) 50-99 parts by weight of (meth)acrylate ester monomers;
b) 1-50 parts by weight of polar monomers, inclusive of acid-functional monomers;
wherein the sum of the monomers is 100 parts by weight.

6. The polymerizable composition of claim 5 wherein the monomer mixture comprises:
a) 50-99.9 parts by weight of (meth)acrylate ester monomers;
b) 0.1-15 parts by weight of acid-functional monomers;
c) 0 to <50 parts by weight of polar monomers, exclusive of acid-functional monomers,
wherein the sum of the monomers is 100 parts by weight.

7. The polymerizable composition of claim 4 comprising:
a) 0.01 to 1.0 parts by weight of a photoinitiator, and
b) 0.05 to 0.5 parts be weight of a protected photocrosslinker of claim 1 ,
relative to 100 parts by weight of the monomer mixture.

8. A method of preparing a (meth)acrylate (co)polymer comprising the steps of:
a) photopolymerizing a monomer mixture of at least one (meth)acrylate monomer, a photoinitiator and a protected photoinitiator of claim 4 ;
b) deprotecting the protected photocrosslinker, and
c) photocrosslinking the resulting copolymer.

9. The method of claim 8 wherein the monomer mixture of step a) comprises:
50-99 parts by weight of (meth)acrylate ester monomers;
1-50 parts by weight of polar monomers, inclusive of acid-functional monomers;
wherein the sum of the monomers is 100 parts by weight.

10. The method of claim 8 wherein the monomer mixture of step a) comprises:
50-99.9 parts by weight of (meth)acrylate ester monomers;
0.1-15 parts by weight of acid-functional monomers;
0 to <50 parts by weight of polar monomers, exclusive of acid-functional monomers,
wherein the sum of the monomers is 100 parts by weight.

11. The method of claim 8 wherein the monomer mixture of the first photopolymerization step is fully converted to uncrosslinked copolymer.

12. The method of claim 8 wherein the monomer mixture of the first photopolymerization step is converted up to 30% to uncrosslinked copolymer.

13. The method of claim 8 wherein the product of step a) is a (meth)acrylate copolymer having pendent, protected photocrosslinker groups.

14. The method of claim 13 wherein the uncrosslinked copolymer is of the formula:
—(M ester ) b -(M acid ) c -(M polar ) d -(M PX *) c —

where
M ester represents polymerized monomer units derived from (meth)acrylate monomers,
M acid represents polymerized monomer units derived from acid functional monomers,
M polar represents polymerized monomer units derived from non-acid functional polar monomers,
M PX * represents polymerized monomer units derived from the protected photocrosslinker, and
subscripts b, c, d and e represent the parts by weight of each monomer in the copolymer.

15. The method of claim 8 wherein the step of deprotecting provides an uncrosslinked copolymer of the formula:
—(M ester ) b -(M acid ) c -(M polar ) d -(M PX ) e —

M ester represents polymerized monomer units derived from (meth)acrylate monomers,
M acid represents polymerized monomer units derived from acid functional monomers,
M polar represents polymerized monomer units derived from non-acid functional polar monomers,
M PX represents polymerized monomer units derived from the deprotected photocrosslinker, and
subscripts b, c, d and e represent the parts by weight of each monomer in the copolymer.

16. The method of claim 8 wherein the step of further photocrosslinking photolyzes the deprotected photocrosslinker group and crosslinks the (meth)acrylate polymer.

17. The method of claim 8 comprising the steps of:
1) photopolymerizing a monomer mixture to provide a syrup polymer composition comprising a solute copolymer having pendent, protected photocrosslinking groups;
2) thermally polymerizing the syrup polymer composition to produce a copolymer composition wherein the photocrosslinking groups are deprotected;
3) optionally coating the copolymer composition of step 2), and
4) photocrosslinking the copolymer composition by exposure to UV radiation.

18. A copolymer of the formula:
—(M ester ) b -(M acid ) c -(M polar ) d -(M PX *) e —

where
M ester represents polymerized monomer units derived from (meth)acrylate monomers,
M acid represents polymerized monomer units derived from acid functional monomers,
M polar represents polymerized monomer units derived from non-acid functional polar monomers,
M PX * represents polymerized monomer units derived from the protected photocrosslinker of claim 4 , and
subscripts b, c, d and e represent the parts by weight of each monomer in the copolymer.

19. The copolymer of claim 18 comprising:
a) 50-99.9 parts by weight of (meth)acrylate ester monomers;
b) 0.1-15 parts by weight of acid-functional monomers;
c) 0 to <50 parts by weight of polar monomers, exclusive of acid-functional monomers, and
d) 0.05 to 0.5 parts be weight of the protected photocrosslinker;
relative to 100 parts by weight of the monomer mixture.

Assignees

• 3M Innovative Properties Co

Inventors

• Benson Karl E
• Behling Ross E
• Kurian Anish
• Prince Ryan B
• Wurst Joshua R
• Wohl Adam R
• Webb Robert J
• Ozair Sehban

Classifications

• C09J133/08 Primary

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C08F2/48 Primary

  by ultraviolet or visible light · CPC title

• C07C69/54 Primary

  Acrylic acid esters; Methacrylic acid esters · CPC title

• C08F220/18

  with acrylic or methacrylic acids · CPC title

• C08F220/1808

  C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate · CPC title