Abstract: Copolycondensation of a hydroxyl group-containing naphthalene and xylene with an aldehyde compound gives a polyhydroxy aromatic compound. The hydroxyl group-containing naphthalene comprises at least one of naphthols and dihydroxynaphthalenes. In the polyhydroxy aromatic compound, the proportions of the naphthalene unit and xylene unit are 95 to 50:5 to 50 (mole percent), and each molecule contains 2 to 20 naphthalene units. The polyhydroxy aromatic compound is useful as an epoxy resin curing agent. Reaction of the polyhydroxy aromatic compound with an epihalohydrin gives an epoxy resin. An epoxy resin composition can be prepared from the epoxy resin and a curing agent.

Abstract: Copolycondensation of .alpha.-naphthol and .beta.-naphthol with an aldehyde compound gives a poly-hydroxynaphthalene compound having an average molecular weight of 300 to 2,000. This compound is useful as a curing agent for epoxy resins and as a precursor of epoxy resins. Epoxy resin compositions include (1) compositions comprising an epoxy resin and the poly-hydroxynaphthalene compound as a curing agent and (2) compositions comprising an epoxy resin obtained by reacting the poly-hydroxynaphthalene compound with an epihalohydrin and a curing agent. The epoxy resin compositions of the invention are characterized in that the cured resins have a high glass transition temperature and high heat stability and high moisture resistance, scarcely allowing package cracking even in soldering treatment. Therefore the compositions are suited for use in encapsulating semiconductors.

Abstract: Coarse coal particles are pulverized to at least 70% passing through a standard 200 mesh screen in the presence of water in an amount to form aqueous coal slurries having a coal concentration from 60 to 80% by weight. The pulverization is carried out also in the presence of polyether typed polyoxyalkylene adducts having a high molecular weight with polyols having at least three active hydrogen atoms, phenol/aldehyde condensates of polyalkyleneimines, or derivatives of these adducts.

Abstract: Mixture of a fuel oil and pulverized coal are stabilized by the addition of a small amount of a polyether-type adduct having a molecular weight of from 6,000 to 600,000 between a lower alkylene oxide and a poly(lower alkyleneimine) compound, or a derivative of said adduct.

Abstract: A fuel slurry comprising a mixture of a fuel oil and pulverized coal may be effectively stabilized with a small amount of adducts of alkylene oxide and an alcohol, an amine, a carboxylic acid or a phenol, or inorganic acid esters of said adducts; or cross-linked products of said adducts or said inorganic acid esters.

Abstract: A fuel slurry comprising a mixture of a fuel oil and pulverized coal may be effectively stabilized with a small amount of a condensation product of a sulfonated benzene or naphthalene derivative-formaldehyde, ligninsulfonic acid, carboxymethylcellulose, carboxymethyl-starch or a salt thereof.