Monovinylarene conjugated diene block copolymer compositions for shrinkable films
View Patent ↗The present invention relates generally to monovinylarene-conjugated diene block copolymers adapted for shrinkable film applications. In one embodiment, a block copolymer is provided wherein an oriented 2 mil film of the block copolymer oriented at 100° C. or less exhibits less than 10% shrinkage at 70° C., and at least 70% shrinkage at 100° C.
1. A block copolymer composition, comprising:
a monovinylarylene-conjugated diene coupled block copolymer comprising:
an initially formed block, wherein the initially formed block is a monovinylarylene block that is 15-30 wt % of the block copolymer;
a random mixed block of monovinylarylene and conjugated diene,
wherein the random mixed block comprises 4-9 times as much monovinylarylene as conjugated diene; and
20-30 wt % conjugated diene.
2. The block copolymer composition of claim 1 , wherein the monovinylarylene is styrene and the conjugated diene is 1,3-butadiene.
3. The block copolymer composition of claim 1 , wherein the conjugated diene is 1,3-butadiene or isoprene, or a mixture thereof.
4. The block copolymer composition of claim 1 , wherein the monovinylarylene is styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-t-butylstyrene, 2,4-dimethylstyrene, 4-cyclohexylstyrene, 4-decylstyrene, 2-ethyl-4-benzylstyrene, 4-(4-phenyl-n-butyl)styrene, 1-vinylnaphthalene, s-vinylnaphthalene, or a mixture thereof.
5. The block copolymer composition of claim 1 , wherein the coupled block copolymer is formed through a charge order: i-A-B-C-CA, wherein
“i” is a polymerization initiator charge;
“A” is a monovinylarylene charge;
“B” is a conjugated diene charge;
“C” is a mixed charge of monovinylarylene and conjugated diene polymerized under polymerization conditions that result in the random mixed block of monovinylarylene and conjugated diene; and
“CA” is a coupling agent,
6. The block copolymer composition of claim 1 , wherein the coupled block copolymer is formed through a charge order: i-A-C-B-CA, wherein
“i” is a polymerization initiator charge;
“A” is a monovinylarylene charge;
“B” is a conjugated diene charge;
“C” is a mixed charge of monovinylarylene and conjugated diene polymerized under polymerization conditions that result in the random mixed block of monovinylarylene and conjugated diene; and
“CA” is a coupling agent.
7. The block copolymer composition of claim 1 , wherein the coupled block copolymer is formed through a charge order: i-A-i-C-B-CA, wherein
“i” is a polymerization initiator charge;
“A” is a monovinylarylene charge;
“B” is a conjugated diene charge;
“C” is a mixed charge of monovinylarylene and conjugated diene polymerized under polymerization conditions that result in the random mixed block of monovinylarylene and conjugated diene; and
“CA” is a coupling agent.
8. A shrinkable film or sheet, comprising:
a monovinylarylene-conjugated diene coupled block copolymer comprising:
an initially formed block, wherein the initially formed block is a monovinylarylene block that is 15-30 wt % of the block copolymer;
a random mixed block of monovinylarylene and conjugated diene,
wherein the random mixed block comprises 4-9 times as much monovinylarylene as conjugated diene; and
20-30 wt % conjugated diene.
9. The shrinkable film or sheet of claim 8 , wherein the coupled block copolymer is formed through a charge order: i-A-B-C-CA, wherein
“i” is a polymerization initiator charge;
“A” is a monovinylarylene charge;
“B” is a conjugated diene charge;
“C” is a mixed charge of monovinylarylene and conjugated diene polymerized under polymerization conditions that result in the random mixed block of monovinylarylene and conjugated diene; and
“CA” is a coupling agent.
10. The shrinkable film or sheet of claim 8 , wherein the coupled block copolymer is formed through a charge order: i-A-C-B-CA, wherein
“i” is a polymerization initiator charge;
“A” is a monovinylarylene charge;
“B” is a conjugated diene charge;
“C” is a mixed charge of monovinylarylene and conjugated diene polymerized under polymerization conditions that result in the random mixed block of monovinylarylene and conjugated diene; and
“CA” is a coupling agent.
11. The shrinkable film or sheet of claim 8 , wherein a 2 mil film of the block copolymer oriented at 100° C. or less that has a haze of no more than 5%.
12. The shrinkable film or sheet of claim 8 , wherein a 2 mil film of the block copolymer oriented at 100° C. or less that has a natural shrinkage of no more than 5%.
13. The shrinkable film or sheet of claim 8 , wherein a 2 mil film of the block copolymer oriented at a temperature of at least 80° C. exhibits the following properties:
less than 17% shrinkage when immersed for 30 seconds in an oil bath at 70° C.;
at least 42% shrinkage when immersed for 30 seconds in an oil bath at 80° C.; and
at least 73% shrinkage when immersed for 30 seconds in an oil bath at 100° C.
14. A method of producing a monovinylarene-conjugated diene block copolymer, comprising:
charging an initiator and a monovinylarylene monomer and allowing polymerization to occur to produce an initially formed monovinylarylene block;
charging a randomizer and a conjugated diene/monovinylarene monomer mixture and allowing polymerization to occur to produce a random mixed block comprising 4-9 times as much monovinylarylene as conjugated diene; and
charging a reaction mixture of the initially formed monovinylarene block and the random mixed block with a coupling agent to form the monovinylarene-conjugated diene block copolymer;
wherein the initially formed monovinylarylene block is 15-30 wt % of the block copolymer; and
wherein the block copolymer comprises 20-30 wt % conjugated diene.
15. The method of claim 14 , wherein the initiator is n-butyI lithium.
16. The method of claim 14 , comprising charging a conjugated diene monomer and allowing polymerization to occur to produce a conjugated diene block.
17. The method of claim 16 , comprising performing the charging through a charge order: i-A-B-C-CA, wherein
“i” comprises charging the initiator;
“A” comprises charging the monovinylarylene monomer;
“B” comprises charging the conjugated diene monomer;
“C” comprises charging the randomizer and the conjugated diene/monovinylarene monomer mixture; and
“CA” comprises charging the reaction mixture with the coupling agent.
18. The method of claim 16 , comprising performing the charging through a charge order: i-A-C-B-CA, wherein
“i” comprises charging the initiator;
“A” comprises charging the monovinylarylene monomer;
“B” comprises charging the conjugated diene monomer;
“C” comprises charging the randomizer and the conjugated diene/monovinylarene monomer mixture; and
“CA” comprises charging the reaction mixture with the coupling agent.