Cross-linked polymer particle for epoxy resin, epoxy resin composition, and epoxy cured material

Fabrication Example 1

Cross-Linked Polymer Particle (C-1)

[0045]In a 2 L separable flask equipped with a stirrer, a reflux cooling tube, a temperature control apparatus and a nitrogen introduction tube, 175 parts of ion-exchange water was added. Then, in a beaker with a certain size, 100 parts of ion-exchange water, 90 parts of cyclohexyl methacrylate as the vinyl monomer (c1), 10 parts of ethylene glycol dimethacrylate as the crosslinking monomer (c2), 1 part of sodium dodecylbenzene-sulfonate as a surfactant, and 0.2 part of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (trade name: “Perocta O”, produced by NOF Corporation) as an oil-soluble initiator are mixed. A mixer “Ultra-Turrax T-25” made by IKA Company was used to treat the mixture for 3 minutes to obtain a monomer emulsion.

[0046]The obtained monomer emulsion was poured in the separable flask and heated to 70° C. An exothermic peak accompanying with the polymerization reaction was observed when the system temperature was aroun

Fabrication Example 2

Cross-Linked Polymer Particle (C-2)

[0048]A powder of the cross-linked polymer particle (C-2) was obtained in the same way as in Fabrication Example 1 except that 80 parts of cyclohexyl methacrylate was used as the vinyl monomer (c1), 10 parts of ethylene glycol dimethacrylate was used as the crosslinking monomer (c2) and 10 parts of glycidyl methacrylate was used as the vinyl monomer (c3) having glycidyl. The solid content of the emulsion of the cross-linked polymer particle (C-2) was 23.6%. The volume-average primary particle size of the cross-linked polymer particle (C-2) was 2.64 μm.

Fabrication Example 3

Core-Shell Polymer Particle (D-1)

[0049]In a 2 L separable flask equipped with a stirrer, a reflux cooling tube, a temperature control apparatus and a nitrogen introduction tube, 143.3 parts of ion-exchange water was added. Then, 2.8 parts of butyl acrylate, 2.2 parts of styrene, and 0.1 part of allyl methacrylate were added, and the mixture was heated to 80° C. When the system temperature reached 80° C. and was confirmed to be stable, an aqueous solution of ammonium persulfate, which was obtained by dissolving 0.1 part of ammonium persulfate in 6.1 parts of ion-exchange water, was added in the system to perform polymerization of seed particles. After an exothermic peak was observed, the system was maintained for 30 minutes to obtain seed particles.

[0050]Next, as core components, 45.5 parts of butyl acrylate, 18.4 parts of styrene, 1.6 part of allyl methacrylate, 0.6 part of ammonium di-2-ethylhexylsulfosuccinate as an emulsifying agent, and 31.9 parts of ion-exchan