Adhesive compositions comprising mixtures of block copolymers
View Patent ↗The present invention relates to adhesive compositions that comprise: i. at least one block copolymer (i)(a) of the formula A-I-A (1) or (A-I) n X (2) and at least one block copolymer (i)(b) of the formula A-(I-B)-A (3) or [A-(I/B)] n -X (4), wherein each A independently is a polymer block of an aromatic vinyl compound, I is a poly(isoprene) polymer block, (I/B) is a mixed random polymer block of isoprene and butadiene in a weight ratio I:B of from about 20:80 to about 80:20, n is an integer equal to or greater than 2 and X is the residue of a coupling agent, and wherein the weight ratio between said block copolymers (i)(a) and (i)(b) is such that the overall butadiene content in component (i) is less than 20 wt %, ii. a tackifying resin, and iii. optionally one or more plasticizers. Tapes, labels or bandages that are obtained by applying the adhesive compositions of the present invention to a carrier are also provided.
1. An adhesive composition comprising,
i. at least one block copolymer (i)(a) of the formula A-I-A (1) or (A-I) n X (2), and at least one block copolymer (i)(b) of the formula A-(I/B)-A (3) or [A-(I/B)] n -X (4), wherein each A is independently a polymer block of an aromatic vinyl compound, each I is a poly(isoprene) polymer block, each (I/B) is a mixed random polymer block of isoprene and butadiene in a weight ratio of I:B of from 20:80 to 80:20, n is an integer equal to or greater than 2 and X is the residue of a coupling agent, and wherein the weight ratio between said block copolymers (i)(a) and (i)(b) is such that the overall butadiene content in component (i) is less than 20 wt %,
ii. a single tackifying resin selected from modified aliphatic hydrocarbon resins that are not aromatic modified, and iii. one or more plasticizers.
2. The adhesive composition of claim 1 , wherein the block copolymers (i)(a) and (i)(b) each have a poly(vinyl aromatic) content in the range of from 15 to 35 wt %.
3. The adhesive composition of claim 1 , wherein the (I/B) weight ratio in the block copolymer (i)(b) is in the range of from 30:70 to 70:30.
4. The adhesive composition of claim 2 , wherein the (I/B) weight ratio in the block copolymer (i)(b) is in the range of from 30:70 to 70:30.
5. The adhesive composition of claim 1 , wherein the (I/B) weight ratio in the block copolymer (i)(b) is in the range of from 40:60 to 60:40.
6. The adhesive composition of claim 2 , wherein the (I/B) weight ratio in the block copolymer (i)(b) is in the range of from 40:60 to 80:20.
7. The adhesive composition of claim 1 , wherein the block copolymers (i)(a) and (i)(b) each have a weight average molecular weight in the range of from 100,000 to 500,000.
8. The adhesive composition of claim 6 , wherein the block copolymers (i)(a) and (i)(b) each have a weight average molecular weight in the range of from 150,000 to 250,000.
9. The adhesive composition of claim 1 , wherein the block copolymer (i)(a) comprises a multiblock copolymer according to formula (1) to (2) and a diblock copolymer A-I in a weight ratio in the range of from 100:0 to 30:70.
10. The adhesive composition of claim 9 , wherein the block copolymer (i)(b) comprises a multiblock copolymer according to formula (2) to (4) and a diblock copolymer A-(I/B) in a weight ratio in the range of from 100:0 to 30:70.
11. The adhesive composition of claim 1 , wherein the block copolymer (i)(b) comprises a multiblock copolymer according to formula (2) to (4) and a diblock copolymer A-(I/B) in a weight ratio in the range of from 100:0 to 30:70.
12. The adhesive composition of claim 1 , wherein the tackifying resin shows a differential scanning calorimeter (DSC) glass transition temperature between 30 and 60° C.
13. The adhesive composition of claim 1 , wherein the tackifying resin shows a softening point between 80 and 110° C.
14. The adhesive composition of claim 1 , wherein the tackifying resin is a C5 hydrocarbon resin, showing a Ring and Ball softening point between 85 and 97° C.
15. The adhesive composition of claim 1 , comprising from 50 to 300 parts by weight of resin per 100 parts by weight of block copolymer component (i).
16. The adhesive composition of claim 15 , wherein the one or more plasticizers are present in an amount of from 10 to 85 parts by weight of plasticizer per 100 parts by weight of block copolymer component (i).
17. Tapes, labels or bandages that are obtained by applying an adhesive composition comprising,
i. at least one block copolymer (i)(a) of the formula A-I-A (1) or (A-I) n X (2), and at least one block copolymer (i)(b) of the formula A-(I/B)-A (3) or [A-(I/B)] n -X (4), wherein each A is independently a polymer block of an aromatic vinyl compound, each I is a poly(isoprene) polymer block, each (I/B) is a mixed random polymer block of isoprene and butadiene in a weight ratio of 1:B of from 20:80 to 80:20, n is an integer equal to or greater than 2 and X is the residue of a coupling agent, and wherein the weight ratio between said block copolymers (i)(a) and (i)(b) is such that the overall butadiene content in component (i) is less than 20 wt %,
ii. a single tackifying resin selected from modified aliphatic hydrocarbon resins that are not aromatic modified, and
iii. one or more plasticizers, to a carrier.
18. The adhesive composition of claim 17 , wherein the tackifying resin is a C5 hydrocarbon resin.
19. An adhesive composition comprising,
i. at least one block copolymer (i)(a) of the formula A-I-A (1) or (A-I) n X (2), and at least one block copolymer (i)(b) of the formula A-(I/B)-A (3) or [A-(I/B)] n -X (4), wherein each A is independently a polymer block of an aromatic vinyl compound, each I is a poly(isoprene) polymer block, each (I/B) is a mixed random polymer block of isoprene and butadiene in a weight ratio of I:B of from 20:80 to 80:20, n is an integer equal to or greater than 2 and X is the residue of a coupling agent, and wherein the weight ratio between said block copolymers (i)(a) and (i)(b) is such that the overall butadiene content in component (i) is less than 20 wt %,
ii. a tackifying resin, iii. one or more plasticizers;
and wherein said composition excludes aromatic tackifying resins.
20. The adhesive composition of claim 17 , wherein the tackifying resin is a C5 hydrocarbon resin.