Polyamide/aliphatic polyester block copolymer, process for the production thereof, and blend containing the same

A method for forming an intimate blend of a thermoplastic resin having no or poor compatibility with a polyamide, and a polyamide, which comprises intimately blending a thermoplastic resin selected from the group consisting of a polyester resin, a polycarbonate resin, a polyester carbonate resin, an acrylonitrile-butadiene-styrene resin, an acrylonitrile-styrene resin and a polyphenylene oxide resin, and the polyamide in the presence of a compatibilizing agent comprising a polyamide/aliphatic polyester block copolymer comprising

• (A) a polyamide block composed substantially of at least one recurring unit selected from the group consisting of a recurring unit of the formula (1), ##STR23## wherein R.sub.1 is an alkylene group having 4 to 12 carbon atoms, recurring unit of the formula (2) ##STR24## wherein R.sub.2 is an alkylene group having 4 to 12 carbon atoms or an alkylene-arylene-alkylene group having 8 to 16 carbon atoms, and R.sub.3 is an alkylene group having 4 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, and mixtures of recurring units of formula (1) and formula (2);
• and an aliphatic polyester block composed substantially of at least one recurring unit selected from the group consisting of a recurring unit of the formula (3) ##STR25## wherein R.sub.4 is an alkylene group having 1 to 12 carbon atoms, a recurring unit of the formula (4) ##STR26## wherein R.sub.5 is an alkylene group having 2 to 12 carbon atoms and R.sub.6 is an alkylene group having 2 to 12 carbon atoms, and mixtures of recurring units of formula (3) and formula (4);
• said block copolymer having the following properties (B), (C) and (D):
• (B) satisfying the following expression (5),
• T.sub.1 -T<100-C (5)
• wherein T is the melting point (.degree.C.) of the above block copolymer, T.sub.1 is the melting point (.degree.C.) of a polyamide composed of the polyamide block and C is the content (wt. %) of the polyamide block,
• (C) exhibiting the extraction amount which satisfies the expression (6), when extracted in tetrahydrofuran,
• E<(100-C).times.0.4 (6)
• wherein E is the extraction amount (wt. %) when the block copolymer is refluxed in tetrahydrofuran of which the weight is 100 times the weight of the block copolymer under heat for 2 hours, and C is the content (wt. %) of the polyamide block, and
• (D) having an intrinsic viscosity, measured at 35.degree. C., in the range of from 0.5 to 5.

An intimate blend comprising the product obtained by intimately blending a thermoplastic resin having no or poor compatibility with polyamide, a polyamide resin and a compatibilizing agent, said thermoplastic resin being selected from the group consisting of a polyester resin, a polycarbonate resin, a polyester carbonate resin, an acrylonitrile-butadiene-styrene resin, an acrylonitrile-styrene resin and a polyphenylene oxide resin, and said compatibilizing agent being a polyamide/aliphatic polyester block copolymer comprising

• (A) (I) a polyamide block composed substantially of at least one recurring unit selected from the group consisting of a recurring unit of the formula (1), ##STR27## wherein R.sub.1 is an alkylene group having 4 to 12 carbon atoms, recurring unit of the formula (2) ##STR28## wherein R.sub.2 is an alkylene group having 4 to 12 carbon atoms or an alkylene-arylene-alkylene group having 8 to 16 carbon atoms, and R.sub.3 is an alkylene group having 4 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, and mixtures of recurring units of formula (1) and formula (2);
• and (II) an aliphatic polyester block composed substantially of at least one recurring unit selected from the group consisting of a recurring unit of the formula (3) ##STR29## wherein R.sub.4 is an alkylene group having 1 to 12 carbon atoms, a recurring unit of the formula (4) ##STR30## wherein R.sub.5 is an alkylene group having 2 to 12 carbon atoms and R.sub.6 is an alkylene group having 2 to 12 carbon atoms and mixtures of recurring units of formula (3) and formula (4);
• said block copolymer having the following properties (B), (C) and (D):
• (B) satisfying the following expression (5),
• T.sub.1 -T<100-C (5)
• wherein T is the melting point (.degree.C.) of the above block copolymer, T.sub.1 is the melting point (.degree.C.) of a polyamide composed of the polyamide block and C is the content (wt. %) of the polyamide block,
• (C) exhibiting the extraction amount which satisfies the expression (6), when extracted in tetrahydrofuran,
• E<(100-C).times.0.4 (6)
• wherein E is the extraction amount (wt. %) when the block copolymer is refluxed in tetrahydrofuran of which the weight is 100 times the weight of the block copolymer under heat for 2 hours, and C is the content (wt. %) of the polyamide block, and
• (D) having an intrinsic viscosity, measured at 35.degree. C., in the range of from 0.5 to 5.