AU543450B2

AU543450B2 - Ternary polycarbonate compositions containing polyacrylate and thermoplastic polyester

Info

Publication number: AU543450B2
Application number: AU75318/81A
Authority: AU
Inventors: P.Y. Liu
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1981-08-10
Filing date: 1981-08-10
Publication date: 1985-04-18
Anticipated expiration: 2001-08-10
Also published as: AU7531881A

Description

Ternary Polycarbonate Compositions Containing Polyacrylate and Thermoplastic Polyester The present invention is directed to high molecular weight, aromatic polycarbonate compositions having improved aged impact strength and improved low temrperature impact strength.

BACKGROUND OF THE INVENTION It is well known that high molecular weight, aromatic polycarbonate resins have high impact strength below a critical thickness of between about 1/2 and 1/4 inches. Above this average thickness, the impact strength of such polycarbonate resins is low. It is also known that the impact strength of these polycar bonate resins decreases rapidly as temperatures decrease below about -5°C as well as after aging at elevated temperatures above about 100°C. These characteristics limit the fields of applications of these resins. Thus, unmodified polycarbonates are not practical for use at low or high temperatures when good impact strength is required. Therefore, it is desirable to improve the impact strength of polycarbonate resins at both low and high temperatures as well as improve their aged impact strength and thereby expand the fields of application of such resins.

In copending application Serial No. 957,801 filed November 6, 1978 polyester compositions having improved impact are described. These compositions comprise (a) a polybutylene terephthalate which can also include another polyester copolymer, (b) a polyacrylate, and (c) an aromatic polycarbonate. The amount of polyacrylate employed can range from about 5-20 weight percent while the amount of aromatic polycarbonate employed can range from about 10-20 weight percent. Thus, the primary component in these compositions is the polyester so that the polyacrylate and polycarbonate portions are employed as the modifiers.

Polycarbonate compositions having improved impact strength at both high and low temperatures as well as improved aged impact strength are disclosed in co-pending applications Serial Nos. as in U.S. Patents 4,018,750 and 4,123,436. Transesterification processes can also be employed to prepare these resins such as are disclosed in U.S. Patent 3,153,008, as well as other processes known to those skilled in the art. In addition, the aromatic polycarbonates of the invention can include the polymeric derivates of a dihydric phenol, a dicarboxylic acid, and carbonic acid, such as are disclosed in U.S. Patent 3,169,131.

It is also possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired for use in preparing the arcαatic polycarbonate to be employed in the invention. In addition, blends of any of the above materials can be used to provide the aromatic polycarbonate.

Further, branched polycarbonates, such as are disclosed in U.S. Patent 4,001,184 can also be employed as can blends of a linear polycarbonate and a branched polycarbonate to provide the aromatic polycarbonate of the invention.

The "acrylate" copolymer employed in the invention is a copolymer of a C₁-C₅ methacrylate and a C₁- C₅ acrylate, wherein the "C₁-C₅" represents both saturated and unsaturated, straight or branched chained aliphatic hydrocarbon radicals having from 1 to 5 carbon atoms and which can be employed in amounts of about 2-4 parts by weight per hundred parts of aromatic polycarbonate.

Preferred acrylates for use in the acrylate copolymer are methyl acrylate, ethyl acrylate, isobutyl acrylate, 1,4-butanediol diacrylate, n-butyl acrylate, and 1,3-butylene diacrylate. Pre ferred methacrylates for use in this copolymer include methyl methacrylate, isobutyl methacrylate, 1,3-butylene diraethacrylate, butyl methacrylate and ethyl methacrylate.

Based on the total weight of the copolymer, the acrylate portion thereof can range from about 50-85 weight percent and the methacrylate portion thereof can range from about 15-50 weight percent.

The preferred acrylate copolymer for use in this invention is a copolycer of n-butyl acrylate and methyl methacrylate wherein the weight ratio of n-butyl acrylatei methyl methacrylate is about 3:2.

Suitable acrylate copolymers can be prepared by methods well known to those skilled in the art or can be obtained commercially. For example, Rohm and Haas' Acryloid KM 330 copolymer, a copolymer of n-butyl acrylate and methyl methacrylate, is suitable for use in the present invention.

The thermoplastic polyesters which can be employed in the invention include, for example, aliphatic/aromatic polyesters such as poly (1,4-butylene terephthalate); poly (ethylene terephthalate) and the like, as well as block copolyesters such as cyclohexylenedimethanol copolymers as well as blends and mixtures thereof.

Other thermoplastic polyesters suitable for use in the compositions of the invention will become apparent to those skilled in the art while others are commercially available such as those sold under the "VALOX" trademark. For both high and low temperature applications, the preferred thermoplastic polyester is poly (1,4-butylene terephthalate).

The amount of thermoplastic polyester which can be employed in the ternary compositions of the invention can range from about 0.5-2.5 parts by weight, preferably 1.0-2.0 parts by weight, per hundred parts of the aromatic polycarbonate. It is also regarded to be among the features of this invention to include in the ternary polycarbonate composition conventional additives for purposes such as reinforcing, coloring or stablizing the composition in conventional amounts.

The compositions of the invention are prepared by raechanically blending the high molecular weight aromatic polycarbonate with the thermoplastic polyester and the acrylate copolymer by conventional methods.

EXAMPLES The following examples set forth the best mode' currently known to illustrate the invention and should not be construed as limiting the scope of the invention. In the examples, all parts and percentages are by weight unless otherwise specified.

EXAMPLE 1 Ninety-four (94.0) parts of an aromatic polycarbonate, derived from 2,2-bis (4-hydroxyphenyl) propane and having an intrinsic viscosity (I.V.) in the range of from about 0.46 to about 0.49 dl/g as determined in methylene chloride solution at 25°C, was mixed with four (4) parts of an acrylate copolymer of n-butyl acrylate and methyl methacrylate having a weight ratio of n-butylacrylatei methyl methacrylate of about 3:2, and two (2.0) parts of poly (1,4-butylene terephthalate): i.e. PBT. The ingredients were then blended together by mechanically mixing them in a laboratory tumbler and the resulting mixture was fed to an extruder which was operated at about 265°C. The resulting extrudate was comminuted into pellets and the pellets were injection molded at about 290°C - 310°C into test specimens of about 5" by 1/2" by 1/4" and 5" by 1/2" by 1/8", the latter dimensions being the specimen thicknesses. Izod impact strengths of these specimens were measured according to the notched Izod test, ASTH D256, and are set forth in Table I. The ductile-brittle (D/B) transition temperatures, (the highest temperature at which a sample begins to exhibit a brittle mode of failure rather than a ductile mode of failure) were obtained according to the procedures of ASTK D256 and are also listed in Table I. The sample labeled CONTROL was obtained from a polycarbonate resin having an I.V. of about 0.46 0.49 dl/g and was prepared without either the acrylate copolymer or the thermoplastic polyester.

EXAMPLE 2 The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, acrylate copolymer and PBT in the test specimen were, respectively, 95, 4 and 1. The test results obtained are listed in Table I.

EXAMPLE 3 The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, acrylate copolymer and PBT in the test specimens were, respectively, 96, 3 and 1. The test results obtained are listed in Table I.

EXAMPLE 4 The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, acrylate copolymer and PBT in the test specimens were, respectively, 95.5, 4 and 1.5. The test results obtained are listed in Table I.

Claims

1. A ternary polycarbonate composition comprising in admixture, a high molecular weight aromatic polycarbonate, a minor amount of an acrylate copolymer which is a copolymer of a C₁-C₅ acrylate and a C₁-C₅ methacrylate, and a minor amount of a thermoplastic polyester.

2. The composition of claim 1 wherein said acrylate copolymer is present in an amount of about 2 - 4 parts-by weight per hundred parts of aromatic polycarbonate.

3. The composition of claim 1 wherein said thermoplastic polyester is present in an amount of about 0.5 - 2.5 parts by weight per hundred parts of aromatic polycarbonate.

4. The composition of claim 3 wherein said thermoplastic polyester is present in an amount of about 1.0 - 2.0 parts by weight per hundred parts of aromatic polycarbonate.

5. The composition of claim 1 wherein the acrylate portion of said acrylate copolymer is selected from the group consisting of ethyl acrylate, n-butyl acrylate, 1,3-butylene diacrylate, isobutyl acrylate, 1,4-butanediol diacrylate and methyl acrylate and the methacrylate portion of said acrylate copolymer is selected from the group consisting of methyl methacrylate, 1,3 butylene dimethacrylate, isobutyl methacrylate, butyl methacrylate and ethyl methacrylate.

6. The composition of claim 5 wherein the aromatic polycarbonate is derived from 2,2-bis (4-hydroxyphenyl) propane.

7. The composition of claim 5 wherein the weight ratio of acrylate: methacrylate in said acrylate copolymer ranges from about 15-50: 50-85.

8. The composition of claim 1 wherein said thermoplastic polyester is a member selected from the group consisting of poly

(1,4-butylene terephthalate), poly (ethylene terephthalate), cyclohexylene dimethanol copolymer, and mixtures thereof.

9. A ternary polycarbonate composition comprising an admixture of a high molecular weight aromatic polycarbonate; an acrylate copolymer in an amount of about 2-4 parts by weight per hundred parts of said aromatic polycarbonate, said acrylate copolymer being a copolymer of a C₁-C₅ acrylate and a C₁-C₅ methacrylate, said acrylate being a member selected from the group consisting of methyl acrylate, ethyl acrylate, n-butyl acrylate, 1,3-butylene diacrylate, isobutyl acrylate, and 1,4-butanediol diacrylate, and said methacrylate being a member selected from the group consisting of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, and 1,3-butylene dimethacrylate; and, a thermoplastic polyester in an amount of about 0.5 - 2.5 parts by weight per hundred parts of said aromatic polycarbonate and selected from the group consisting of poly(1, 4-butylene terephthalate), poly (ethylene terephthalate), cyclohexylenedimethanol copolymer, and mixtures thereof.

10. The composition of claim 9 wherein said aromatic polycarbonate is derived from 2,2-bis (4-hydroxy phenyl) propane.

11. The composition of claim 9 wherein said thermoplastic- polyester is present in an amount of about 1.0 - 2.0 parts by weight per hundred parts of said aromatic polycarbonate.

12. The composition of claim 9 wherein the weight ratio of acrylate: methacrylate in said acrylate copolymer ranges from about 15-50: 50-85.