Block copolymers having distinct isoprene and butadiene midblocks, method for making same, and uses for such block copolymers
View Patent ↗A block terpolymer for use in photocurable compositions, flexographic printing plates or hot melt adhesives having a molecular structure according to the general formula: A-I-B-I-A (1) or (A-I-B) n -X (2), wherein each A is independently a polymer block of predominantly an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein: (a) the weight ratio of I to B is in a range of 30:70 to 70:30; (b) the aromatic vinyl compound content of the block copolymer is from about 14 to about 45%; (c) the B block has a 1,2-vinyl bond content in the range of from about 20 to about 90 mol %; (d) the A block has an apparent molecular weight in the range of from about 5,000 to about 20,000, and the I and B blocks together have a molecular weight in the range of from about 50,000 to about 200,000; (e) uncoupled triblock, S-I-B in the range of from about 2% to about 60%.
1. An elastomeric block copolymer comprising a molecular structure according to the general formula:
A-I-B-I-A (1)
or
(A-I-B) n -X (2),
wherein each A is independently a polymer block of predominantly an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein:
(i) the weight ratio of I to B is in a range of 30:70 to 70:30;
(ii) the aromatic vinyl compound content of the block copolymer is 14 to 45 wt %;
(iii) the B block has a 1,2-vinyl bond content in the range of from 30 to 60 mol %;
(iv) the A block has an apparent molecular weight in the range of from 5,000 to 20,000, and the I and B blocks together have an apparent molecular weight in the range of from 50,000 to 200,000; and
(v) the coupling efficiency of (A-I-B) n -X ranges from 40% to 98%.
2. The elastomeric block copolymer of claim 1 wherein the aromatic vinyl compound is predominantly polystyrene.
3. The elastomeric block copolymer of claim 2 , wherein the 1,2, vinyl bond content is greater than 40 mol %.
4. The elastomeric block copolymer of claim 2 , wherein the I and B blocks together have an apparent molecular weight in the range of from 75,000 to 200,000.
5. The elastomeric block copolymer of claim 2 , wherein the polystyrene content is from 14 to 25%.
6. A photocurable composition comprising:
(a) an elastomeric block copolymer comprising a molecular structure according to the general formula:
A-I-B-I-A (1)
or
(A-I-B) n -X (2),
wherein each A is independently a polymer block of predominantly an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein:
(i) the weight ratio of I to B is in a range of 30:70 to 70:30;
(ii) the aromatic vinyl compound content of the block copolymer is 14 to 45 wt %;
(iii) the B block has a 1,2-vinyl bond content in the range of from 30 to 60 mol %;
(iv) the A block has an apparent molecular weight in the range of from 5,000 to 20,000, and the I and B blocks together have an apparent molecular weight in the range of from 50,000 to 200,000; and
(v) the coupling efficiency of (A-I-B) n —X ranges from 40% to 98%
(b) from 1 to 60% by weight, based on the weight of components (a) and (b), of one or more ethylenically unsaturated compounds;
(c) from 0.1 to 10% by weight, based on the weight of the total photocurable composition of one or more photoinitiators or photoinitiator systems; and
(d) from 0 to 40% by weight, based on the total photocurable compound, of one or more auxiliaries.
7. The photocurable composition of claim 6 , wherein component (a) is from 20 to 98.9 wt %, based on the total weight of components (a) and (b).
8. The photocurable composition of claim 6 , wherein component (a) is at least 40% by weight, based on the total weight of components (a) and (b).
9. The photocurable composition of claim 6 , wherein the tri-block content occurs in a content of at most 40% based on the weight of components (a) and (b).
10. The photocurable composition of claim 6 , wherein the aromatic vinyl compound of the elastomeric block copolymer is predominantly aromatic vinyl compound.
11. The photocurable composition of claim 6 , wherein the 1,2, vinyl bond content of the elastomeric block copolymer is greater than 40 mol %.
12. The photocurable composition of claim 6 , wherein the I and B blocks of the elastomeric block copolymer together have an apparent molecular weight in the range of from 75,000 to 150,000.
13. The photocurable block copolymer of claim 6 , wherein the aromatic vinyl content of the elastomeric block copolymer is from 14 to 25%.
14. A flexographic printing plate derived from the photocurable composition according to claim 6 .
15. A flexographic printing plate derived from a photocurable composition, said flexographic printing plate comprising a support layer, one or more photocurable layers comprising:
(a) 20 to 98.0% by weight, based on the weight of components (a) and (b), of one or more elastomeric block copolymers comprising a molecular structure according to the general formula:
A-I-B-I-A (1)
or
(A-I-B) n -X (2),
wherein each A is independently a polymer block of an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein:
(i) the weight ratio of I to B is in a range of 30:70 to 70:30;
(ii) the aromatic vinyl compound content of the block copolymer is 14 to 45 wt %;
(iii) the B block has a 1,2-vinyl bond content in the range of from 20 to 90 mol %;
(iv) the A block has an apparent molecular weight in the range of from 5,000 to 20,000, and the I and B blocks together have an apparent molecular weight in the range of from 50,000 to 200,000; and
(v) the coupling efficiency of (A-I-B) n -X ranges from 40% to 98%
(b) from 1 to 60% by weight, based on the weight of components (a) and (b), of one or more ethylenically unsaturated compounds;
(c) from 0.1 to 10% by weight, based on the total weight of the photocurable composition, of one or more photoinitiators or photoinitiator systems;
(d) from 0 to 40% by weight, based on the total photopolymerizable composition of one or more auxiliaries.
16. The flexographic printing plate of claim 15 , wherein component (a) is from 20 to 98.9% of the weight of components (a) and (b).
17. The flexographic printing plate of claim 15 , wherein component (a) is at least 40% based on the weight of components (a) and (b).
18. An adhesive composition comprising a radiation sensitive block copolymer having the general formula:
A-I-B-I-A (1)
or
(A-B) n -X (2),
wherein each A is independently a polymer block of predominantly an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein:
(i) the weight ratio of I to B is in a range of 30:70 to 70:30;
(ii) the aromatic vinyl compound content of the block copolymer is 14 to 45 wt %;
(iii) the B block has a 1,2-vinyl bond content in the range of from 30 to 60 mol %;
(iv) the A block has an apparent molecular weight in the range of from 5,000 to 20,000, and the I and B blocks together have an apparent molecular weight in the range of from 50,000 to 200,000; and
(v) the coupling efficiency of (A-I-B) n -X ranges from 40% to 98%.
19. The adhesive composition of claim 18 wherein the adhesive composition is a hot melt adhesive.
20. The adhesive composition of claim 18 wherein the adhesive composition is a pressure sensitive adhesive.