Thermoplastic compositions based on grafted rubber and polyester, a process for their manufacture, and articles obtained therefrom

Thermplastic composition based on a crystalline polyester and a modified vinylaromatic polymer consisting essentially of:

• (1) from 80 to 90% by weight based on the total weight of the thermoplastic composition of at least one polymer phase (A) comprising at least one terpolymer produced by grafting (a) at least one vinylaromatic monomer and (b) at least one unsaturated nitrile onto (c) at least one rubber, said terpolymer being dispersed in a matrix of a copolymer comprising units derived from (d) at least one unsaturated nitrile and (e) at least one vinylaromatic monomer, the overall composition of the polymer phase (A) being such that it contains from 17 to 35 parts of unsaturated nitrile, from 10 to 60 parts of rubber, and from 10 to 60 parts of vinylaromatic monomer per 100 parts by weight of said phase and,
• (2) from 10 to 20% by weight based on the total weight of the thermoplastic composition of at least one high molecular weight polybutylene terephthalate (B), the polybutylene terephthalate having a molecular weight between 80,000 and 150,000 weight average molecular weight,
• and further comprising at least one lubricant, wherein the thermoplastic composition has a Vicat softening point above 113.degree. C. and an Izod impact strength not below 330 J/m.

Thermoplastic composition comprising:

• (1) from 50 to 97% by weight based on the total weight of the thermoplastic composition of at least one polymer phase (A) comprising at least one terpolymer produced by grafting (a) at least one vinylaromatic monomer and (b) at least one unsaturated nitrile onto (c) at least one rubber, said terpolymer being dispersed in a matrix of a copolymer comprising units derived from (d) at least one unsaturated nitrile and (e) at least one vinylaromatic monomer, the overall composition of the polymer phase (A) being such that it contains from 17 to 35 parts of unsaturated nitrile, from 10 to 60 parts of rubber, and from 10 to 60 parts of vinylaromatic monomer per 100 parts by weight of said phase and,
• (2) from 3 to 50% by weight based on the total weight of the thermoplastic composition of at least one high molecular weight polybutylene terephthalate (B), the polybutylene terephthalate having a molecular weight between 80,000 and 150,000 weight average molecular weight,
• wherein the thermoplastic composition has a Vicat softening point above 113.degree. C. and an Izod impact strength not below 330 J/m, and is produced by the process comprising mixing said phase (A) and said polybutylene terephthalate (B) at a temperature above the melting temperature of the polybutylene terephthalate (B) for a sufficient time to produce a homogeneous composition.