Abstract: Disclosed herein is a method of preparing a high-melting point flame retardant crystal, comprising the steps of: reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with 1,4-naphthoquinone in an inert solvent having a dielectric constant of 10 or less to reduce a content of by-products, thereby obtaining a reaction composition; and dissolving the reaction composition in any one solvent selected from the group consisting of ethyleneglycol, propyleneglycol, diethyleneglycol, cyclohexanone, benzyl alcohol, acetate ester, benzoate ester and a mixture thereof to recrystallize and refine the reaction composition, thereby obtaining high-melting point retardant crystal, represented by Formula 1, having a start melting point of 280° C. or more and a melting point of 291° C. or more, which are measured by differential thermogravimetric analysis.

Abstract: Disclosed herein is a method of preparing a high-melting point flame retardant crystal, comprising the steps of: reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with 1,4-naphthoquinone in an inert solvent having a dielectric constant of 10 or less to reduce a content of by-products, thereby obtaining a reaction composition; and dissolving the reaction composition in any one solvent selected from the group consisting of ethyleneglycol, propyleneglycol, diethyleneglycol, cyclohexanone, benzyl alcohol, acetate ester, benzoate ester and a mixture thereof to recrystallize and refine the reaction composition, thereby obtaining high-melting point retardant crystal, represented by Formula 1, having a start melting point of 280° C. or more and a melting point of 291° C.

Abstract: A flame-retardant synthetic resin composition characterized by comprising 1-40 parts by weight of at least one type of organic phosphorus compound represented by the following general formula (1): (wherein R1 represents alkyl, aralkyl, etc.) with respect to 100 parts by weight of a synthetic resin.

Abstract: A flame-retardant synthetic resin composition characterized by comprising 1-40 parts by weight of at least one type of organic phosphorus compound represented by the following general formula (1): (wherein R1 represents alkyl, aralkyl, etc.) with respect to 100 parts by weight of a synthetic resin.

Abstract: A method for preparing a sulfone represented by the following formula: ##STR1## wherein R' represents a lower alkyl group, an aryl group or an aryl group whose nucleus has at least one substituent selected from the group consisting of a halogen atom, nitro group, a lower alkyl group, phenyl group and a phenyl group substituted with a halogen atom, or an alkali metal salt thereof. A sulfonic acid ester of 4-hydroxybiphenyl is condensed at a temperature of 0.degree. to 200.degree. C. in a presence of a Lewis acid or a super-strong acid with a sulfonyl chloride represented by the formula R'SO.sub.2 Cl, wherein R' is the same as that defined above.

Abstract: An engineering plastic composition with excellent flowability, heat stability, and desirable mechanical properties is provided. The composition contains an engineering plastic material and an aliphatic polyester.

Abstract: A polyester is provided that comprises as main monomer components thereof a dicarboxylic acid and a diol, including a p-quaterphenyl derivative of specific formula. The use of appropriate kinds of dicarboxylic acid for the polyester makes it possible to obtain a thermoplastic elastomer or an engineering platic material (i.e., liquid-crystal polymer).

Abstract: A method for preparing a sulfone represented by the following formula: ##STR1## wherein R and R' each represent a lower alkyl group, an aryl group or an aryl group whose nucleus has at least one substituent selected from the group consisting of a halogen atom, nitro group, a lower alkyl group, phenyl group and a phenyl group substituted with a halogen atom, comprises the step of condensing a sulfonic acid ester of 4-hydroxybiphenyl represented by the following formula: ##STR2## with a sulfonyl chloride of R'SO.sub.2 Cl at a temperature of 0.degree. to 200.degree. C. in the presence of a Lewis acid or a superstrong acid.

Abstract: A polyester is provided that comprises as main monomer components thereof a dicarboxylic acid and a diol, including a p-quaterphenyl derivative of specific formula. The use of appropriate kinds of dicarboxylic acid for the polyester makes it possible to obtain a thermoplastic elastomer or an engineering plastic material (i.e., liquid-crystal polymer).

Abstract: An engineering plastic composition with excellent flowability, heat stability, and desirable mechanical properties is provided. The composition comprises an engineering plastic material and at least one p-quaterphenyl derivative of specific formula.