Abstract: A process for preparing epoxy resin comprises a step of allowing a mixture of epichlorohydrin, 2,2-bis(p-hydroxyphenyl)propane, and a solvent in the presence of an alkali used in an amount of from 0.4 to 5% by weight of the epichlorohydrin to stay at a temperature of from 45.degree. to 70.degree. C. to obtain a homogeneous mass. Subsequently an alkali used in an amount of from 45 to 50% by weight of the epichlorohydrin is added to the resultant mass, and polycondensation is conducted at a temperature of 70.degree. to 90.degree. C. under stirring to obtain the end product.

Abstract: A method for preparing biuret-structure polyisocyanates which comprises reacting 1,6-hexamethylenediisocyanate with water which is introduced into the reaction zone in the form of vapors in a mixture with air or an inert gas at a moisture content of said mixture of from 0.1 to 2.0 kg/kg and temperature of from 110.degree. to 130.degree. C. The reaction is carried out at a temperature ranging from 150.degree. to 170.degree. C.The polyisocyanates having biuret structure as produced by the method according to the present invention have a molecular mass of about 800, the content of isocyanate groups is as high as 23.59%. No polyurea is formed in the reaction. The process is single-staged, technologically simple and can be performed continuously.