Elastic, moisture-vapor permeable films, their preparation and their use
View Patent ↗The present disclosure relates to films such as membranes and coatings and to coated articles. The films comprise a combination of at least one elastomeric styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups, and at least one sulfonated block copolymer. Films comprising the optionally functionalized block copolymer(s) and the additional sulfonated block copolymer(s) are elastic and are moisture-vapor permeable, and thus useful as coatings in breathable clothing and footwear, industrial workwear including cleanroom coveralls, in medical applications such as wound dressings and protective clothing, for bed sheets and mattress or seat covers, and other non-apparel applications.
1. A film comprising
a) at least one elastomeric styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups,
b) at least one sulfonated block copolymer having at least one end block A and at least one interior block B wherein each A block contains essentially no sulfonic acid or sulfonate ester functional groups and each B block is a polymer block containing from about 10 to about 100 mol % sulfonic acid or sulfonate ester functional groups based on the number of sulfonation susceptible monomer units of the B block, and
wherein (a) and (b) are present in weight a ratio of from about 0.1:1 to about 10:1.
2. The film of claim 1 , wherein the ratio of (a) to (b) is from about 0.5:1 to about 5:1.
3. The film of claim 1 , wherein the styrenic block copolymer (a) has a general configuration A-B, A-B-A, (A-B) n , (A-B-A) n , (A-B-A) n X, (A-B) n X or a mixture thereof, wherein n is an integer from about 2 to about 30, and X is the residue of a coupling agent, each A block independently is a polymer block of one or more alkenyl arenes having a number average molecular weight of from 3,000 to 60,000; and
each B block independently is a polymer block of one or more conjugated dienes and from 0to about 75%-wt. of one or more alkenyl arenes, which block contains no significant levels of olefinic unsaturation and has a number average molecular weight of from 10,000 to 300,000;
wherein the total amount of alkenyl arenes in the block copolymer (a) is from about 2 to about 75%-wt.
4. The film of claim 3 , wherein the total amount of alkenyl arenes in the styrenic block copolymer (a) is from about 5 to about 65%-wt.
5. The film of claim 1 wherein the styrenic block copolymer component (a) comprises at least one S-E/B-S or S-E/P-S block copolymer which is optionally functionalized.
6. The film of claim 1 wherein the styrenic block copolymer component (a) consists of one or more non-functionalized styrenic block copolymers.
7. The film of claim 1 wherein the styrenic block copolymer component (a) consists of one or more functionalized styrenic block copolymers.
8. The film of claim 1 wherein the styrenic block copolymer component (a) consists of one or more functionalized styrenic block copolymers and one or more non-functionalized styrenic block copolymers.
9. The film of claim 1 , wherein the sulfonated block copolymer (b) has a general configuration A-B-A, A-B-A-B-A, (A-B-A) n X, (A-B) n X, A-D-B-D-A, A-B-D-B-A, (A-D-B) n X, (A-B-D) n X or mixtures thereof, where n is an integer from 2 to about 30, and X is a coupling agent residue and wherein each D block is a polymer block resistant to sulfonation and the plurality of A blocks, B blocks, or D blocks are the same or different.
10. The film of claim 9 , wherein each D block of the sulfonated block copolymer (b) is selected from the group consisting of (i) a polymerized or copolymerized conjugated diene selected from isoprene, 1,3-butadiene having a vinyl content prior to hydrogenation of between 20 and 80 mol percent, (ii) a polymerized acrylate monomer, (iii) a silicon polymer, (iv) polymerized isobutylene and (v) mixtures thereof, wherein any segments containing polymerized 1,3-butadiene or isoprene are subsequently hydrogenated.
11. The film of claim 1 , having no more than 50% set at 50% elongation.
12. The film of claim 1 , having a moisture vapor transmission rate of at least 1,000 g/m 2 /day as measured by the procedure described herein.
13. The film of claim 1 , wherein (a) and (b) are present in weight a ratio of from about 7:3 to 3:7.
14. A coated article comprising a substrate and a coating comprising
a) at least one styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups,
b) at least one sulfonated block copolymer having at least one end block A and at least one interior block B wherein each A block contains essentially no sulfonic acid or sulfonate ester functional groups and each B block is a polymer block containing from about 10 to about 100 mol % sulfonic acid or sulfonate ester functional groups based on the number of sulfonation susceptible monomer units of the B block, and
wherein (a) and (b) are present in weight a ratio of from about 0.1:1 to about 10:1.
15. The coated article of claim 14 , wherein the substrate is a natural or synthetic, woven and non-woven material, or a mixture thereof.
16. The coated article of claim 14 , wherein the substrate is flexible or elastic.
17. The coated article of claim 14 wherein the styrenic block copolymer component (a) consists of one or more non-functionalized styrenic block copolymers.
18. The coated article of claim 14 , wherein (a) and (b) are present in weight a ratio of from about 7:3 to 3:7.
19. An elastic membrane comprising
a) at least one styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups,
b) at least one sulfonated block copolymer having at least one end block A and at least one interior block B wherein each A block contains essentially no sulfonic acid or sulfonate ester functional groups and each B block is a polymer block containing from about 10 to about 100 mol % sulfonic acid or sulfonate ester functional groups based on the number of sulfonation susceptible monomer units of the B block, and
wherein (a) and (b) are present in weight a ratio of from about 0.1:1 to about 10:1, having no more than 50% set at 50% elongation, and having a moisture vapor transmission rate of at least 1,000 g/m 2 /day as measured by the procedure described herein.
20. The elastic membrane of claim 19 wherein the styrenic block copolymer component (a) consists of one or more non-functionalized styrenic block copolymers.
21. The elastic membrane of claim 19 , wherein (a) and (b) are present in weight a ratio of from about 7:3 to 3:7.
22. A coating or film-casting composition comprising a liquid phase and
a) at least one styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups,
b) at least one sulfonated block copolymer having at least one end block A and at least one interior block B wherein each A block contains essentially no sulfonic acid or sulfonate ester functional groups and each B block is a polymer block containing from about 10 to about 100 mol % sulfonic acid or sulfonate ester functional groups based on the number of sulfonation susceptible monomer units of the B block, and
wherein (a) and (b) are present in weight a ratio of from about 0.1:1 to about 10:1.
23. The composition of claim 22 , wherein the liquid phase comprises one or more organic solvents.
24. The composition of claim 23 , wherein the liquid phase comprises one or more aprotic organic solvents.
25. The composition of claim 22 having a solids content of no more than 50%-wt.
26. The composition of claim 25 , which is in form of an aqueous or non-aqueous dispersion.
27. The composition of claim 25 , which is in form of a non-aqueous dispersion or solution.
28. The coating or film-casting composition of claim 22 wherein the styrenic block copolymer component (a) consists of one or more non-functionalized styrenic block copolymers.
29. The coating or film-casting composition of claim 22 , wherein (a) and (b) are present in weight a ratio of from about 7:3 to 3:7.