Producing granular epoxy resin by refining and pulverizing solid epoxy resin

1. A production method of granular epoxy resin comprising:

an epoxy resin preparing step of preparing an epoxy resin which is solid at ordinary temperature by reaction between a phenol compound and epihalohydrin;

a purifying processing step of refining the prepared epoxy resin which is solid at ordinary temperature so that the total content of compounds having a molecular weight of 200 or less is 0.28% by mass or less of the entire epoxy resin; and

a pulverizing step of pulverizing the refined epoxy resin obtained by the purifying processing step under conditions so as not to make the total content of compounds having a molecular weight of 200 or less exceeding 0.3% by mass,

wherein the epoxy resin which is solid at ordinary temperature prepared by said epoxy resin preparing step is mainly composed of at least one selected from oligomers represented by the following general formula (1) and oligomers represented by the following general formula (2), and

at least 50% by mass of the entire epoxy resin consists of at least one oligomer of n 1 =0 in the following general formula (1) and having a molecular weight of 500 or less and/or at least one oligomer of n 2 =0 in the following general formula (2) and having a molecular weight of 500 or less;

wherein in the above formula (1), G is a glycidyl group;

R 1 is a hydrocarbon group having from 1 to 10 carbon atoms and each R 1 can be the same or different;

X is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—, or a group represented by the following general formula (3) and each X can be the same or different;

wherein the above formula (3), G is a glycidyl group, R 3 is a hydrogen atom or a hydrocarbon group having from 1 to 5 carbon atoms;

p 1 is an integer between 0 and 4 and each p 1 can be the same or different;

n 1 is an integer between 0 and 10;

wherein the above formula (2), R 2 is a hydrocarbon group having from 1 to 10 carbon atoms and each R 2 can be the same or different;

Y is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—, —CO—, —SO 2 —, or a direct bond and each Y can be the same or different;

p 2 is an integer between 0 and 4 and each p 2 can be the same or different;

n 2 is an integer between 0 and 10.

2. A production method of granular epoxy resin comprising:

an epoxy resin preparing step of preparing an epoxy resin which is solid at ordinary temperature by reaction between a phenol compound and epihalohydrin;

a purifying processing step of refining the prepared epoxy resin which is solid at ordinary temperature so that the total content of compounds having a molecular weight of 200 or less is 0.28% by mass or less of the entire epoxy resin; and

a pulverizing step of pulverizing the refined epoxy resin obtained by the purifying processing step under conditions so as not to make the total content of compounds having a molecular weight of 200 or less exceeding 0.3% by mass,

wherein the epoxy resin which is solid at ordinary temperature prepared by said epoxy resin preparing step is mainly composed of at least one selected from oligomers represented by the following general formula (1) and oligomers represented by the following general formula (2), and

at least 20% by mass of the entire epoxy resin consists of at least one oligomer of n 1 =0 in the following general formula (1) and having a molecular weight 400 or less and/or at least one oligomer of n 2 =0 in the following general formula (2) and having a molecular weight of 400 or less;

wherein the above formula (1), G is a glycidyl group;

R 1 is a hydrocarbon group having from 1 to 10 carbon atoms and each R 1 can be the same or different;

X is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—, or a group represented by the following general formula (3) and each X can be the same or different;

wherein the above formula (3), G is a glycidyl group, R 3 is a hydrogen atom or a hydrocarbon group having from 1 to 5 carbon atoms;

p 1 is an integer between 0 and 4 and each p 1 can be the same or different;

n 1 is an integer between 0 and 10;

wherein the above formula (2), R 2 is a hydrocarbon group having from 1 to 10 carbon atoms and each R 2 can be the same or different;

Y is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—, —CO—, —SO 2 —, or a direct bond and each Y can be the same or different;

p 2 is an integer between 0 and 4 and each p 2 can be the same or different;

n 2 is an integer between 0 and 10.