Styrene-based block copolymer latex
A latex of a styrene-based block copolymer includes a styrene-based block copolymer and water. The styrene-based block copolymer includes a toluene insoluble content of 30 to 95 wt %. The latex of the styrene-based block copolymer is superior in the processability and can provide a molded film such as a dip-molded product having the high tear strength, the high stress retention and the soft texture.
1. A latex of a styrene-based block copolymer comprising a styrene-based block copolymer and water, the styrene-based block copolymer comprising a toluene insoluble content of 30 to 95 wt %, wherein the viscosity at 25° C. is 10 to 300 cps when a solid content concentration is set to 55 wt %.
2. The latex of the styrene-based block copolymer according to claim 1 , wherein the styrene-based block copolymer is a styrene-based block copolymer represented by the following general formula (1),
A-B—Y—(B-A) n (1)
in the general formula (1), each of A is independently a polymer block containing 90 wt % or more of a unit derived from an alkenyl aromatic hydrocarbon; Y is a single bond or a residue of a coupling agent having functionality; each of B is independently a polymer block containing 90 wt % or more of a unit derived from a conjugated diene; and “n” is 0 to 5.
3. The latex of the styrene-based block copolymer according to claim 1 , wherein the styrene-based block copolymer is a styrene-isoprene block copolymer.
4. A molded film comprising the latex of the styrene-based block copolymer according to claim 1 .
5. A packaging structure capable of accommodating an object between a first sheet substrate and a second sheet substrate, wherein at least a part of the first sheet substrate and at least a part of the second sheet substrate are bonded and laminated by a film comprising the latex of the styrene-based block copolymer according to claim 1 .
6. A substrate with an adhesive layer, the adhesive layer being formed on a surface of the substrate, the adhesive layer comprising the latex of the styrene-based block copolymer according to claim 1 .
7. A method for producing the latex of the styrene-based block copolymer according to claim 1 , comprising:
adding a radical polymerization initiator to a latex of a styrene-based block copolymer prior to cross-linking as a raw material; and
cross-linking the styrene-based block copolymer prior to cross-linking as a raw material in the form of the latex to form a toluene insoluble component.
8. The method for producing the latex of the styrene-based block copolymer according to claim 7 , wherein the radical polymerization initiator is a peroxide polymerization initiator.
9. The method for producing the latex of the styrene-based block copolymer according to claim 7 , comprising:
adding an activator in addition to the radical polymerization initiator to proceed the cross-linking reaction.
10. A method for producing a dip-molded product, comprising:
obtaining the latex of the styrene-based block copolymer by the method according to claim 7 ; and
dip-molding the obtained latex of a styrene-based block copolymer.