Latex comprising water and a styrenic block copolymer and a process for preparing articles therefrom

Patent metadata

Field	Value
Publication number	US-9321932-B2
Application number	US-201214238242-A
Country	US
Kind code	B2
Filing date	Aug 9, 2012
Priority date	Aug 12, 2011
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

Articles with enhanced tensile strength and comfort are prepared from a latex comprising water and a styrenic block copolymer, wherein the styrenic block copolymer has 2 or more poly(vinyl aromatic) blocks and at least one block of polymerized conjugated diene, wherein the styrenic block copolymer has a weight average molecular weight of 150,000 to 250,000, the poly(vinyl aromatic) blocks have a weight average molecular weight ranging from 9,000 to 15,000, and the content of poly(vinylaromatic) blocks in the styrenic block copolymer ranges from 8 to 15% wt, based on the total styrenic block copolymer, by a process which comprises coating a surface with the latex to obtain a film, wherein the latex comprises a vulcanizing agent. The invention also provides a latex comprising such a styrenic block copolymer and a vulcanizing agent, as well as a styrenic block copolymer that is particularly suitable for use in such a latex.

First claim

The invention claimed is:

1. A latex comprising water and a styrenic block copolymer, wherein the styrenic block copolymer has 2 or more poly(vinyl aromatic) blocks, said poly(vinyl aromatic) blocks are a polystyrene block, containing less than 5 wt % of copolymerizable monomer, based on the weight of poly(vinyl aromatic) block and at least one block of polymerized conjugated diene, said conjugated diene is a polyisoprene block, containing less than 5 wt % of copolymerizable monomer, based on the weight of block polymerized conjugated diene, wherein the styrenic block copolymer has a weight average molecular weight of 170,000 to 220,000, the poly(vinyl aromatic) blocks have a weight average molecular weight ranging from 9,000 to 14,000, and the content of poly(vinylaromatic) blocks in the styrenic block copolymer ranges from 9 to 14% wt, based on the total styrenic block copolymer, and a vulcanising agent.

2. A latex according to claim 1 , wherein the vulcanising agent comprises a sulphur compound and, optionally, one or more accelerators.

3. A latex according to claim 2 , wherein one or more accelerators are used and are selected from the group consisting of sulphenamide compounds, thiazole compounds, thiuram compounds, dithiocarbamates, xanthates and guanidines.

4. A latex according to claim 2 , wherein the sulphur compound has been selected from the group consisting of sulphur, thiuram sulphides, dithiodimorpholine, caprolactam disulphide, dialkylthiophosphoryl disulphide, diisopropylxanthogen polysulphide, and mixtures thereof.

5. A latex according claim 2 , wherein the amount of the sulphur compound ranges from 0.2 to 4 parts by weight per hundred parts by weight of the combination of water and styrenic block copolymer.

6. A latex according to claim 1 , wherein the styrenic block copolymer is of the general formula A-B-A, wherein each block A independently is a poly(vinyl aromatic) block, and wherein block B is a block of polymerized conjugated diene, wherein each block independently is a homopolymer block or a copolymer block, and optionally a block B is partly hydrogenated.

7. A latex according to claim 1 , wherein the styrenic block copolymer has been prepared by sequential polymerization of
(i) a vinyl aromatic monomer or a mixture (a) composed for at least 95 wt % of a vinyl aromatic monomer and at most 5 wt % of a copolymerizable monomer, based on the weight of the mixture (a),
(ii) a conjugated diene or a mixture (b) composed for at least 95 wt % of a conjugated diene, and at most 5 wt % of a copolymerizable monomer based on the weight of the mixture (b), and
(iii) a vinyl aromatic monomer or a mixture (c) composed for at least 95 wt % of a vinyl aromatic monomer and at most 5 wt % of a copolymerizable monomer based on the weight of the mixture (c).

8. The latex according to claim 1 , wherein the latex comprises from 20 to 80% by weight of styrenic block copolymer, based on the weight of the combination of water and styrenic block copolymer.

9. A process for preparing articles from a latex according to claim 1 , which process comprises coating a surface with the latex to obtain a film.

10. An article prepared from the latex of claim 1 , in the form of a glove, catheter or condom.

11. Cured, vulcanized latex comprising a styrenic block copolymer comprising 2 or more poly(vinyl aromatic) blocks and at least one block of polymerized conjugated diene, wherein the styrenic block copolymer has a weight average molecular weight of 170,000 to 220,000, the poly(vinyl aromatic) blocks have a weight average molecular weight ranging from 9,000 to 14,000, and the content of poly(vinylaromatic) blocks in the styrenic block copolymer ranges from 9 to 14% wt, based on the total styrenic block copolymer, said cured, vulcanized latex has a tensile strength ≧23.9 but ≦33.9 MPa, and said latex has a 10% Young's Modulus ≧0.22 but ≦0.25 MPa, according to ASTM D412 and ASTM D3577.

Assignees

• De Jong Wouter
• Kraton Polymers Us Llc

Inventors

• De Jong Wouter

Classifications

• C09D153/025

  modified · CPC title

• A61L29/041

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C08J5/02

  Direct processing of dispersions, e.g. latex, to articles · CPC title

• C08J2353/02

  of vinyl aromatic monomers and conjugated dienes · CPC title

• A61L31/10

  Macromolecular materials · CPC title