Pressure sensitive adhesive, toner for developing electrostatic charge image, method for producing pressure sensitive adhesive, method for producing toner for developing electrostatic charge image, and bonded product
A pressure sensitive adhesive includes: composite resin particles that contain a styrene resin containing, as polymerization components, styrene and a vinyl monomer other than styrene, and a (meth)acrylate resin containing, as a polymerization component, a (meth)acrylate; and an aqueous solvent containing water, in which a mass ratio of the styrene resin to the (meth)acrylate resin (styrene resin:(meth)acrylate resin) is 80:20 to 20:80, a difference between the lowest glass transition temperature and the highest glass transition temperature of the composite resin particles is 30° C. or more, a melt viscosity of the composite resin particles at 100° C. is 4000 Pa·s or more and 20000 Pa·s or less, and, in a melt viscosity range of the composite resin particles of 4000 Pa·s or more and 20000 Pa·s or less, a slope of a logarithm of the melt viscosity of the composite resin particles relative to a temperature of the composite resin particles is −0.08 or more and −0.04 or less.
1 . A pressure sensitive adhesive comprising:
i) composite resin particles that contain, in a polymerized form:
a styrene resin containing, as polymerization components, styrene, butyl acrylate, and acrylic acid,
a (meth)acrylate resin containing, as polymerization components, di(meth)acrylate, butyl acrylate, 2-ethylhexyl acrylate, and styrene, and
a chain transfer agent, and
ii) an aqueous solvent containing water;
wherein:
a mass ratio of the styrene resin to the (meth)acrylate resin (styrene resin:(meth)acrylate resin) is 80:20 to 20:80,
a difference between the lowest glass transition temperature and the highest glass transition temperature of the composite resin particles is 30° C. or more,
a melt viscosity of the composite resin particles at 100° C. is 4000 Pa·s or more and 20000 Pa·s or less,
in a melt viscosity range of the composite resin particles of 4000 Pa·s or more and 20000 Pa·s or less, a slope of a logarithm of the melt viscosity of the composite resin particles relative to a temperature of the composite resin particles is −0.08 or more and −0.04 or less,
the composite resin particles have a gel fraction of 0.1 mass % or more and 2 mass % or less,
a ratio of a content of the di(meth)acrylate to a content of the chain transfer agent in the methacrylate resin of the composite resin particles is from 0.1 to 1.0, and
the chain transfer agent comprises at least one selected from the group consisting of hexylthiol, heptanethiol, octanethiol, nonanethiol, decanethiol, dodecanethiol, tetradecanethiol, and hexadecanethiol.
2 . The pressure sensitive adhesive according to claim 1 , wherein the composite resin particles have a weight average molecular weight of 50,000 or more and 600,000 or less.
3 . The pressure sensitive adhesive according to claim 1 , wherein the di(meth)acrylate includes a 1,10-Decanediol dimethacrylate.
4 . A toner for developing an electrostatic charge image, the toner comprising:
toner particles obtained by aggregating, fusing, and coalescing the composite resin particles contained in the pressure sensitive adhesive according to claim 1 .
5 . A bonded product comprising:
a first adherend;
a second adherend; and
a pressure sensitive adhesive layer formed of the composite resin particles contained in the pressure sensitive adhesive according to claim 1 .
6 . A method for producing the pressure sensitive adhesive according to claim 1 , the method comprising:
preparing a styrene resin particle dispersion in which styrene resin particles containing the styrene resin are dispersed, wherein the styrene resin contains, as polymerization components, styrene, butyl acrylate, and acrylic acid; and
forming composite resin particles by polymerizing, polymerization components of the (meth)acrylate resin, comprising dimethacrylate, butyl acrylate, 2-ethylhexyl acrylate and styrene, in a reaction solution containing the styrene resin particle dispersion and the chain transfer agent;
wherein a mass ratio of the styrene resin to the (meth)acrylate resin (styrene resin:(meth)acrylate resin) is 80:20 to 20:80;
wherein a ratio of a content of the dimethacrylate to a content of the chain transfer agent in the methacrylate resin of the composite resin particles is from 0.1 to 1.0; and
wherein the chain transfer agent comprises at least one selected from the group consisting of hexylthiol, heptanethiol, octanethiol, nonanethiol, decanethiol, dodecanethiol, tetradecanethiol, and hexadecanethiol.