Chloroprene rubber-based polymer latex composition and use thereof
View Patent ↗It is an object of the invention to provide a chloroprene rubber-based polymer latex that has a good balance between initial adhesion and storage stability and is suitable for one-component aqueous adhesive applications. The invention relates to a chloroprene rubber-based polymer latex composition containing a mixture of a chloroprene rubber-based polymer latex and a latex of an acrylic or styrene-acrylic resin-based polymer obtained by copolymerization of a specific carboxyl group-containing unsaturated monomer, in which the specific carboxyl group is neutralized with an alkali.
1. A chloroprene rubber-based polymer latex composition, comprising a mixture of (A) a chloroprene rubber-based polymer latex and (B) an acrylic resin-based polymer latex and/or a styrene-acrylic resin-based polymer latex, wherein the acrylic resin-based polymer latex and/or the styrene-acrylic resin-based polymer latex (B) contains an acrylic resin-based polymer having a unit derived from itaconic acid and/or a styrene-acrylic resin-based polymer having a unit derived from itaconic acid, an alkali is added to the acrylic resin-based polymer latex and/or the styrene-acrylic resin-based polymer latex (B), the chloroprene rubber-based polymer latex (A) contains an anionic surfactant having a carboxyl group, and satisfying formula (1):
[Mathematical Formula 1]
pKa 1 ≧pKa 2+0.6 (1)
wherein pKa1 represents the pKa of the anionic surfactant at 25° C., and pKa2 represents the pKa of itaconic acid at 25° C.
2. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein the anionic surfactant is abietic acid.
3. A one-component aqueous adhesive comprising the chloroprene rubber-based polymer latex composition according to claim 1 .
4. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein pKa2 is at most 4.0.
5. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein the acrylic resin-based polymer latex and/or the styrene-acrylic resin-based polymer latex (B) contains an acrylic resin-based polymer having 0.5 to 2.5 parts by mass of a unit derived from itaconic acid and/or a styrene-acrylic resin-based polymer having 0.5 to 2.5 parts by mass of a unit derived from itaconic acid based on 100 parts by mass of the total amount of monomer units derived from a (meth)acrylic ester and styrene.
6. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein the carboxyl group of a unit derived from itaconic acid is neutralized with an alkali so that a degree of neutralization of 0.7 to 1.3 is attained.
7. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein the mass ratio of the solid in the chloroprene rubber-based polymer latex (A) to the solid in the acrylic resin-based polymer latex and/or the styrene-acrylic resin-based polymer latex (B) is from 60/40 to 95/5.
8. The chloroprene rubber-based polymer latex composition according to claim 1 , wherein the amount of the surfactant used in the chloroprene rubber-based polymer latex (A) is from 1 to 8 parts by mass based on 100 parts by mass of the solid in the chloroprene rubber-based polymer latex (A).