Abstract: Blowing agents of tetrazoles and their derivatives which have a melting point over 200.degree. C. and are used to manufacture the high quality foaming thermoplastic synthetic resin moldings, especially engineering or superengineering plastic moldings and said blowing agents generate no harmful gases and do not cause the deterioration of the thermoplastic synthetic resin moldings.

Abstract: Blowing agents of tetrazoles and their derivatives which have a melting point over 200.degree. C. and are used to manufacture the high quality foaming thermoplastic synthetic resin moldings, especially engineering or superengineering plastic moldings and said blowing agents generate no harmful gases and do not cause the deterioration of the thermoplastic synthetic resin moldings.

Abstract: A transparent polyester film having excellent antistatic properties, which are little effected with variation of the humidity, and further having excellent flexing resistance, pinhole resistance and printability, which is made from a mixture comprising (i) a polyester consisting essentially of a residue of dibasic acids wherein at least 80% by mol is terephthalic acid and a residue of at least one glycol and (ii) a block copolyester consisting of a crystalline polyester segment having a high melting point and a soft polymer segment having a low melting point and a number average molecular weight of 400 to 8,000, said soft polymer segment having a low melting point being contained in an amount of 0.

Abstract: A shaped article having a refractive index of not less than 1.625 at least in one direction and possessing excellent physical properties and various uses, which can be prepared by stretching a molded product, which is made of a polymeric material comprising at least 80 mol% of the repeating units of the formula: ##STR1## and having an intrinsic viscosity of not less than 0.25 dl/g when measured in a mixture of phenol and sym.-tetrachloroethane in a weight ratio of 6 : 4 at 30.degree. C. and has a refractive index of not more than 1.610 at least in one direction, at a temperature of 120.degree. to 230.degree. C. with a stretch ratio of 2 to 20 in the same direction as the refractive index is measured, or by melt extruding the polymeric material at a temperature higher than 230.degree. C. and not higher than 360.degree. C. while or immediately followed by stretching with a deformation speed of not less than 20 times the speed of the melt extrusion.

Abstract: A drawn film of polyamide having an oxygen permeability coefficient of not more than 5 .times. 10.sup.-13 ml.cm/cm.sup.2.sec.cmHg, a breaking strength of not less than 14 kg/mm.sup.2, a breaking elongation of 30 to 150%, a yield strength of not less than 7 kg/mm.sup.2 and a yield elongation of 2 to 6%, which can be manufactured by drawing an undrawn polyamide film biaxially at a temperature within a certain range and optionally heat treating the resulting drawn film, the said undrawn polyamide film being made of a polyamide having a relative viscosity of about 2.0 to 4.0 when measured with a solution thereof in 96% sulfuric acid at a concentration of 1 g/100 ml at 25.degree. C and containing in the molecule not less than 70% (mol) of the repeating unit constituted with metaxylylenediamine or its mixture with paraxylylenediamine and an .alpha.,.omega.

Abstract: A process for preparing a biaxially stretched film of a polyamide blend, which comprises (1) melt extruding a polyamide blend to make an unstretched film and (2) stretching the unstretched film first in the machine direction and then in the transverse direction, or (2') stretching the unstretched film first to make a uniaxially stretched film having a plane orientation index of about 0.6 to 1.7 and then stretching the uniaxially stretched film in a direction substantially at a right angle to the direction at the previous stretching, said polyamide blend comprising 97 to 80% by weight of an .alpha.-type aliphatic polyamide (Component A) and 3 to 20% by weight of at least one polyamide (Component B) selected from the group consisting of (i) an .alpha.-type aliphatic polyamide different from the Component A, (ii) a .gamma.

Abstract: A process for preparing a biaxially stretched film of polyamide blend, which comprises (1) extruding a polyamide blend in melt to make an unstretched film and (2) stretching the unstretched film first in a machine direction with a stretch speed of about 40,000 to 60,000,000 %/minute in a draw ratio of about 2 to 6 and then in a transverse direction with a stretch speed of about 500 to 100,000 %/minute in a draw ratio of about 2 to 6, or (2') stretching the unstretched film first to make a uniaxially stretched film having a plane orientation index of about 0.6 to 1.

Abstract: A transparent polyester film having excellent printability, flexing resistance and pinhole resistance and further excellent interlaminar strength, which is made from a polymer mixture or blend comprising (i) a polyester consisting essentially of a residue of dibasic acids wherein at least 80 % by mol is terephthalic acid and a residue of at least one glycol and (ii) a block copolyester consisting of a crystalline polyester (hard) segment having a high melting point and a soft polymer segment having a low melting point and a number average molecular weight of 400 to 8,000, said soft polymer segment having a low melting point being contained in an amount of 0.5 to 10 % by weight on the basis of the whole weight of the polymer mixture or blend, and said crystalline polyester segment having a melting point of at least 170.degree. C when a polymer is produced by the monomers composing the segment alone and said soft polymer segment having a melting or softening point of 100.degree. C or lower.

Abstract: A block copolymer of 99.8 to 90 % by weight of a polyamide segment and 0.2 to 10 % by weight of a polyether segment dispersed in an island state of not more than about 10 .mu. in particle size, the polyamide segment comprising at least one diamine component containing 100 to 50 mol % (preferably 100 to 70 mol %) of m-xylylenediamine or its mixture with p-xylylenediamine and at least one dicarboxylic acid component containing 100 to 50 mol % (preferably 100 to 70 mol %) of at least one aliphatic dicarboxylic acid having 6 to 12 carbon atoms, the polyether segment comprising at least one polyether having a molecular weight of 2,000 to 20,000 and an amino group or a carboxyl group at at least one terminal position thereof and the block copolymer having a scattering index of not less than 1.

Abstract: A composite film comprising (A) a biaxially drawn film of a polyamide containing in the molecule not less than 70% (mol) of the repeating unit consisting of metaxylylenediamine or its mixture with paraxylylenediamine (of which the content is not more than 30% (mol) on the basis of the total amount of metaxylylenediamine and paraxylylenediamine) and an .alpha.,.omega.-aliphatic dicarboxylic acid having 6 to 10 carbon atoms and (B) a layer of a thermoplastic resin having a melting point or a softening point at least 50.degree. C. below the melting point or the softening point of the polyamide provided on at least one surface of the biaxially drawn film.