EP0451251A1

EP0451251A1 - Polymer blends of polycarabonate, styrenic terpolymer and glass fibers

Info

Publication number: EP0451251A1
Application number: EP90916586A
Authority: EP
Inventors: Charles Franklin Parsons; Curtis M. Miller
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1989-10-31
Filing date: 1990-10-17
Publication date: 1991-10-16
Also published as: JPH04502646A; WO1991006605A1; CA2028585A1; EP0451251A4

Abstract

Les compositions de mélanges polymères comprennent un polycarbonate, un terpolymère de styrène-acrylonitrile-anhydride maléique, et environ 5 à environ 40 % en poids de fibres de verre. Les compositions comprenent, de préférence, environ 5 à environ 65 % en poids du polycarbonate, et environ 10 à environ 80 % en poids du terpolymère. Les compositions peuvent facultativement comprendre une faible quantité d'une résine ABS, afin d'améliorer la compatibilité du polycarbonate et du terpolymère. Ces compositions présentent des combinaisons avantageuses, améliorées de propriétés telles que la résistance à la chaleur, la résistance à une contrainte externe, et un coefficient de conversion permettant d'utiliser le mélange dans des applications thermoplastiques industrielles.The polymer blend compositions include a polycarbonate, a styrene-acrylonitrile-maleic anhydride terpolymer, and about 5 to about 40% by weight glass fibers. The compositions preferably comprise from about 5 to about 65% by weight of the polycarbonate, and from about 10 to about 80% by weight of the terpolymer. The compositions may optionally comprise a small amount of an ABS resin, in order to improve the compatibility of the polycarbonate and the terpolymer. These compositions have advantageous combinations, improved properties such as resistance to heat, resistance to external stress, and a conversion coefficient allowing the mixture to be used in industrial thermoplastic applications.

Description

POLYMER BLENDS OF POLYCARBONATE,

STYRENIC TERPOLYMER AND GLASS FIBERS

RELATED APPLICATIONS

The present application is a continuation-in- part application of copending application Serial No. 165,462 filed March 8, 1988. FIELD OF THE INVENTION

The present invention relates to polymer blend compositions comprising a polycarbonate, a styrenic terpolymer of styrene, acrylonitrile and maleic anhydride, and glass fibers. More particularly, the present invention relates to such polymer blend compositions exhibiting an advantageous combination of physical properties including moduli and heat deflection temperatures.

BACKGROUND OF THE INVENTION

Polymer blend compositions for use in engineering applications should exhibit a combination of heat resistance, good strength and good modulus. Additionally, the blend compositions should exhibit good melt flow properties which facilitate processing and molding of the blend compositions. Polycarbonates are popular blend components owing to their toughness and relatively high softening temperatures. However, owing to their relatively poor melt flow characteristics, polycarbonates are often blended with one or more additional polymers to improve the melt flow properties. While the resulting blends generally exhibit improved melt flow properties, other properties such as heat resistance, impact strength and the like are reduced.

Examples of such blend compositions are known. For example, the Grabowski U.S. Patent No. 3,130,177 discloses blends of polycarbonates with polybutadiene, styrene, acrylonitrile graft polymers while the Grabowski U.S. Patent No. 3,162,695 discloses blends of polycarbonates with butadiene-s tyrene, methyl methacrylate, styrene graft copolymers. The Liebig et al U.S. Patent No. 4,205,140 discloses a thermoplastic molding composition comprising a blend of a polycarbonate, a diene rubber graft polymer such as ABS, and a styrene polymer. Similar blends of polycarbonate with styrene- maleic anhydride copolymer, ABS resin and styrene- acrylonitrile random copolymer are disclosed in the Henton U.S. Patent No. 4,218,544. The Grigo et al U.S. Patent No. 4,472,554 discloses thermoplastic molding compositions comprising a blend of a polycarbonate, a graft polymer such as ABS and a polymeric acidifying agent. The Jones et al U.S. Patents Nos. 4,569,969 and 4,663,389 and European Patent Application No. 135,493 also disclose polymer blends of polycarbonates, ABS polymers and styrene polymers. These blends exhibit various physical properties depending on the type and ratio of components included therein .

The Parsons copending application Serial No . 1 6 5 , 462 dis clo s es blend compo s itions compri s ing polycarbonate , styrene-acrylontrile-maleic anhydride terpolymer and a small amount of an ABS resin which serves as a blending compatibilizer between the polycarbonate and the styrene terpolymer . The compositions exhibit an advantageous combination of impact strength , heat resistance and modulus.

It is also known to add glass fibers to thermoplastic compositions for applications requiring high tensile, compressive and flexural strengths. Glass filled compositions comprising styrene-maleic anhydride copolymers and styrene-maleic anhydride copolymers in combination with polycarbonate are presently commercially available from Arco under the tradenames Dylark® and Arloy® and from Monsanto as Cadon®. Additionally, British Patent No. 1,365,329 discloses glass fiber containing styrene resin compositions, and the Rawlings et al U.S. Patent No. 4,487,881 discloses blends of a polycarbonate, a graft elastomer, a polyanhydride and glass fibers. These compositions also exhibit varying combinations of physical properties. SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide polymer blend compositions which exhibit an advantageous combination of physical properties including heat resistance, good strength and good modulus. It is an additional object of the invention to provide polymer blend compositions which exhibit an advantageous combination of heat resistance, strength and modulus which allows the blends to be used in various engineering thermoplastic blend applications. It is a further object of the invention to provide such compositions which exhibit improved properties, particularly as compared with the individual components of the compositions.

These and additional objects are provided by the blend compositions of the present invention which comprise polycarbonate, styrene-acrylonitrile-maleic anhydride terpolymer and glass fibers. More particularly, the glass fibers are included in an amount of from about 5 to about 40 weight percent based on the polycarbonate, the terpolymer and the glass fibers. Preferably, the polycarbonate is included in an amount of from about 15 to about 65 weight percent, and more preferably from about 20 to about 35 weight percent, and the terpolymer is included in an amount of from about 10 to about 80 weight percent, and more preferably, from about 35 to about 75 weight percent. The compositions exhibit an advantageous combination of physical properties, including good strength, modulus and heat resistance. The blends may optionally contain a small amount of an ABS resin in order to provide further improvements, for example in surface appearance and impact strength, without significantly affecting other advantageous properties of the blend compositions.

These and additional objects and advantages provided by the blend compositions of the present invention will become more apparent in view of the following detailed description.

DETAILED DESCRIPTION The polymer blend compositions of the invention comprise polycarbonate, styrene-acrylonitrile-maleic anhydride terpolymer, and glass fibers in an amount of from about 5 to about 40 weight percent based on the polycarbonate, the terpolymer and the glass fibers. The blend compositions exhibit an advantageous combination of strength, modulus and heat resistance properties.

The polycarbonate component included in the blend compositions may be any aromatic homo-polycarbonate or co-polycarbonate known in the art. The polycarbonate component may be prepared in accordance with any of the processes generally known in the art, for example, by the interfacial polycondensation process, polycondensation in a homogeneous phase or by transesterification. These processes and the associated reactants, catalysts, solvents and conditions are well known in the art and are described in, among others, U.S. Patents Nos. 2,964,974; 2,970,137; 2,999,835; 2,999,846; 3,028,365; 3,153,008; 3,187,065; 3,215,668; and 3,258,414, all of which are incorporated herein by reference. Suitable polycarbonates are based, for example, on one or more of the following bisphenols: dihydroxy diphenyls, bis-(hydroxyphenyl)- alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis- (hydroxyphenyl)-sulphides, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)- sulphoxides, bis-(hydroxyphenyl)-sulphones, α, α-bis- (hydroxyphenyl)-diisopropyl benzenes, and their nucleus- alkylated and nucleus-halogenated derivatives, and mixtures thereof.

Specific examples of these bisphenols are 4,4'- dihydroxy diphenyl, 2,2-bis-( hydroxyphenyl)-propane, 2,4-bis-(4-hydroxyphenyl)-2-metnyl butane, 1,1-bis-(4- hydroxyphenyl)-cyclohexane, α, α-bis-(4-hydroxyphenyl)-p- diisopropyl benzene, 2,2-bis(3-methyl-4-hydroxyphenyl)- propane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, bis- (3,5-dimethyl-4-hydroxyphenyl)-methane, 2,2-bis-(3,5- dimethyl-4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4- hydroxyphenyl)-sulphone, 2,4-bis-(3,5-dimethyl-4- hydroxyphenyl)-2-methyl butane, 1,1-bis-(3,5-dimethyl-4- hydroxyphenyl)-cyclohexane, α, α-bis-(3,5-dimethyl-4- hydroxyphenyl)-p-diisopropyl benzene, 2,2-bis-(3,5- dichloro-4-hydroxyphenyl)-propane and 2,2-bis-(3,5- dibromo-4-hydroxyphenyl)-propane. A particularly preferred bisphenol is 2,2-bis-(4-hydroxyphenyl)-propane, more commonly known as bisphenol A.

The polycarbonate component is included in the blend compositions in an amount sufficient to provide the blend compositions with good tensile and flexural strengths and good heat resistance. Preferably, the polycarbonate component is included in an amount of from about 15 to about 65 weight percent based on the total weight of the polycarbonate, the terpolymer and glass fibers. More preferably, the polycarbonate is included in an amount of from about 20 to about 35 weight percent based on the polycarbonate, the terpolymer and the glass fibers. The present inventors have discovered that 20 or more weight percent of polycarbonate provides the compositions with tensile and flexural strengths greater than those of compositions comprising the terpolymer and glass fibers and as compared with compositions containing polycarbonate and glass fibers. Additionally, the present inventors have discovered that greater than about 35 weight percent polycarbonate begins to decrease the tensile and flexural moduli of the compositions. The second component included in the blend compositions comprises a styrene-acrylonitrile-maleic anhydride terpolymer. Preferably, styrene comprises a majority of the terpolymer composition whereby the terpolymer provides the resultant blend composition with rigidity, good modulus and heat resistance. The maleic anhydride is included in the terpolymer in an amount sufficient to enhance the properties of the styrene component. Preferably, the maleic anhydride comprises f.rom about 4 to about 25 weight percent of the terpolymer. Additionally, the acrylonitrile component of the terpolymer is preferably used in an amount not greater than about 20 weight percent in order that the blend compositions exhibit good melt stability and therefore good processing and molding properties. More preferably, from about 5 to about 20 weight percent acrylonitrile is included in the terpolymer.

The terpolymer is preferably formed in a continuous polymerization process as is well known in the art. In practice, the preparation of the styrene- acrylonitrile-maleic anhydride terpolymer may be controlled to form a product comprising a mixture of the terpolymer and styrene-acrylonitrile copolymer. This mixture of the terpolymer and the copolymer which may result during the production of the terpolymer may also be used in the blend component compositions of the invention as is set forth in the examples.

The styrene-acrylonitrile-maleic anhydride terpolymer is used in an amount sufficient to provide the blends with good rigidity, good modulus and high heat resistance, particularly as indicated by the heat deflection temperature. Preferably, the terpolymer is used in an amount of from about 10 to about 80 weight percent based on the total weight of the polycarbonate, the terpolymer and the glass fibers. More preferably, the terpolymer is included in an amount of from about 35 to about 75 weight percent based on the polycarbonate, the terpolymer and the glass fibers.

The third component of the polymer blend compositions comprises glass fibers which are used in an amount of from about 5 to about 40 weight percent based on the polycarbonate, the terpolymer and the glass fibers.

The glass fibers provide the blend compositions with improved strengths and moduli. Various glass fibers are commercially available and are suitable for use in the present compositions. While various sized glass fibers may be employed in the present compositions, it is preferred that the glass fibers have an average length of from about 0.05 to about 0.5 inches. As will be demonstrated in the examples, glass fibers suitable for use in the present invention are commercially available from Owens-Corning Fiberglass Corporation. Preferably, the glass fibers are included in the present compositions in an amount of from about 10 to about 30 weight percent based on the polycarbonate, the terpolymer and the glass fibers.

Additionally, the blend compositions of the invention may optionally include an ABS resin. When included, the ABS resin is used in an amount sufficient to improve compatibilization between the polycarbonate and the styrene terpolymer components whereby the resultant blend compositions retain the impact strength of the polycarbonate component, the rigidity and good modulus of the styrene terpolymer component and the heat resistance of both the polycarbonate and the terpolymer components. In order to increase the compatibilization of the polycarbonate and terpolymer components without disadvantageously effecting the properties of the blend components, the ABS resin should be used in an amount less than 20 weight percent based on the total weight of the composition. In order to provide improvements, the ABS resin should also be used in an amount of at least about 4 weight percent. In a preferred embodiment, the ABS resin is used in an amount of from about 4 to about 19 weight percent.

The ABS resin comprises a rigid graft polymer grafted to a diene rubber substrate. In a preferred embodiment, the rigid graft polymer is formed from styrene and acrylonitrile and the diene rubber substrate comprises polybutadiene. However, it is well within the scope of the present invention to employ an ABS resin in which the rigid polymer is formed from a monovinylidene aromatic monomer in place of styrene and an acrylate or methacrylate monomer in place of acrylonitrile as is well known in the art. Additionally, the ABS resin may include diene rubbers other than polybutadiene as is well known in the art. In the context of the present application, reference to the ABS resin component will also include these equivalent polymers. It is noted however that ABS resin comprising a rigid graft polymer comprising styrene and acrylonitrile grafted to polybutadiene is the preferred ABS resin. In this preferred embodiment, it is further preferred that the weight ratio of styrene to acrylonitrile in the rigid graft portion of the ABS resin is in the range of about 1:1 to about 5:1 so that the amount of styrene is equal to or greater than the amount of acrylonitrile included in the graft portion. The ABS resin component may be prepared according to methods also well known in the art. As is known in the art, methods of producing ABS resin may result in a product comprising a mixture of ABS graft and ungrafted styrene-acrylonitrile copolymer. These mixtures are also suitable for use in the invention.

The ABS resin should contain at least 30 weight percent, and preferably 50 weight percent, of the diene rubber substrate in order to effect blending compatibilization between the polycarbonate and the terpolymer components. In a preferred embodiment, the ABS resin comprises from about 50 to about 75 weight percent of the diene rubber substrate, and more preferably about 60 to about 70 weight percent.

The blend compositions of the invention may be produced in conventional mixing and compounding apparatus including, for example, single and twin-screw extruders, mixing rolls and internal mixers. The blend compositions may also include various conventional additives including compounding agents, sizing agents, stabilizers, lubricants, flow aids, flame proofing agents, mold release agents, antistatic agents, and the like. Examples of such additives are set forth in U.S. Patents Nos. 4,289,668 and 4,414,342.

The following examples illustrate specific embodiments of the invention. Unless otherwise specified, percentages set forth throughout the examples are weight percentages. The polycarbonate (PC), styrene- acrylonitrile-maleic anhydride terpolymers (SAMA), glass fibers (GF) and ABS resin which were used in the examples are described as follows: PC-1: A polycarbonate obtained from Mobay Chemical Company under the designation M-50.

PC-2: A polycarbonate obtained from General

Electric Company under the tradename Lexan®.

SAMA-1: This terpolymer contained about 21-22 weight percent maleic anhydride and was prepared under steady state conditions in a single reactor. The feed percentages employed were about 81 weight percent styrene, about 9 percent acrylonitrile and about 10-11 percent maleic anhydride. Conversion of the monomer to polymer was approximately 50 percent at which time the resulting warm mass was pumped continuously to a vacuum extruder where unreacted styrene and acrylonitrile were removed and recycled to the reactor. The terpolymer contained little or no styrene-acrylonitrile copolymer as indicated by the absence of a Tg at 104-108°C using differential scanning calorimetry (DSC) analysis.

SAMA-2: This terpolymer contained about 10-11 weight percent maleic anhydride and was prepared in a two reactor system by conducting the resulting warm mass described in the preparation of SAMA-1 into a second reactor where additional polymerization of the unreacted styrene and acrylonitrile occurred. This terpolymer contained up to about 50 weight percent of styrene- acrylonitrile copolymer as indicated by two Tg's appearing in the DSC analysis.

GF-1: Glass fibers (chopped strand) obtained from Owings-Corning Fiberglass Corporation under the designation OCF 408 and having an average length of 3/16 inch.

GF-2: Glass fibers (chopped strand) obtained from Owings-Corning Fiberglass Corporation under the designation OCF 497 and having an average length of 1/8 inch.

ABS: This ABS resin comprised 50 weight percent of a polybutadiene substrate and 50 weight percent of a styrene-acrylonitrile copolymer grafted thereto. The weight ratio of styrene to acrylonitrile in the grafting copolymer was 3:1.

EXAMPLE 1

In this example, a composition according to the present invention was prepared comprising 30 weight percent PC-1, 40 weight percent SAMA-1 and 30 weightpercent GF-1. In this and the following examples, blending was done using a single screw extruder with a low compression screw, and the resulting blends were pelletized and molded into test specimens. Also in this and the following examples, impact strength was measured according to ASTM-D256 (reversed notched impact strength according to Method E), heat distortion was measured according to ASTM-D648 using an unannealed, injection molded sample at 265 psi and the strength and modulus were measured according to ASTM-D638. The composition of this example exhibited a reverse notch impact strength of 3.7 ft-lb/in. at room temperature, a heat distortion temperature of 277°F (1/8 inch sample), a flexural strength of 26,400 psi and a flexural modulus of 16.0 x 10⁵ psi. Thus, the composition exhibited a good combination of physical properties

EXAMPLE 2

In this example, compositions were prepared comprising PC-1, SAMA-2 and GF-1 or GF-2. The weight percentages of these components were varied as set forth in Table I. The compositions were also subjected to measurement of reverse notch impact strength, heat distortion temperature, tensile strength and modulus and flexural strength and modulus, the results of which are also set forth in Table I.

As is evident from Table I, Compositions 2A-2D are according to the present invention while Composition 2E is a comparative composition in that no polycarbonate is included therein. The physical properties of the compositions of the invention set forth in Table I indicate that Composition 2C containing 22.5 weight percent polycarbonate, 67.5 weight percent terpolymer and 10 weight percent glass fibers exhibits a particularly advantageous combination of measured physical properties, particularly heat distortion temperature and tensile and flexural strengths and moduli. EXAMPLE 3

This example further demonstrates compositions according to the present invention and comprising PC-1, SAMA-2 and GF-1 or GF-2. The weight percentages of the components were varied as set forth in Table II. The resulting compositions were subjected to measurement of reverse notch impact strength, heat distortion temperature, and tensile and flexural strength and moduli, the results of which are also set forth in Table II.

As is evident from the compositions described in Table II, Compositions 3A-3E are according to the present invention and exhibit advantageous properties while Composition 3F is a comparative composition which does not contain polycarbonate. Additionally, Composition 3D according to the present invention exhibits a particularly advantageous combination of physical properties including heat distortion temperature and tensile and flexural strength and modulus.

EXAMPLE 4

This example describes compositions according to the present invention further including an ABS resin. Specifically, these compositions comprised PC-1, SAMA-2, GF-1 and ABS in the amounts set forth in Table III. The resulting compositions were subjected to measurement of reverse notch impact strength, heat distortion temperature and tensile and flexural strengths and moduli, the results of which are also set forth in Table III.

Generally , Compositions 4D-4F containing 20 weight percent glass fibers exhibited improved properties as compared with Compositions 4A-4C containing 10 weight percent glass fibers . Additionally, compositions 4C and 4 F contain preferred amounts of the polycarbonate component .

EXAMPLE 5

This example demonstrates blend compositions of the invention containing polycarbonate, terpolymer and glass fibers in the preferred ranges described above.

Several of these compositions also include the optional ABS resin component. The weight percentages of the compositions are set forth in Table IV. These compositions were subjected to measurement of reverse notched and unnotched impact strength, heat distortion temperature and tensile and flexural strengths and moduli, the results of which are also set forth in Table IV.

Compositions 5B and 5E illustrate the increase of tensile and flexural strength obtained with an increase in the polycarbonate content in the blend. Compositions 5C and 5D show the effect of varying the level of the ABS resin. Finally, Compositions 5A and 5E demonstrate the effect of increased glass levels on the moduli and strengths of the compositions.

EXAMPLE 6

This example demonstrates blend compositions according to the present invention containing higher amounts of glass fiber. Specifically, the compositions comprised PC-2, SAMA-2, GF-1 and, optionally, ABS. The weight percentages of the components included in these compositions are set forth in Table V. The compositions were subjected to meas-urement of reversed notch and unnotched impact strength, heat distortion temperature and tensile and flexural strengths and moduli, the results of which are also set forth in Table V.

The results set forth in Table V demonstrate that these compositions exhibited extremely good strength and modulus properties, and good heat distortion temperatures and impact strength.

The preceding examples are set forth to illustrate specific embodiments of the invention and are not intended to limit the scope of the compositions of the present invention. Additional embodiments and advantages within the scope of the claimed invention will be apparent to one of ordinary skill in the art.

Claims

WHAT IS CLAIMED IS:

1. A polymer blend composition, comprising

(a ) polycarbonate,

(b) styrene-acrylonitrile-maleic anhydride terpolymer, and

(c) glass fibers in an amount of from about 5 to about 40 weight percent based on the polycarbonate, the terpolymer and the glass fibers.

2. A polymer blend composition as defined by claim 1, comprising from about 15 to about 65 weight percent polycarbonate, based on the polycarbonate, the terpolymer and the glass fibers.

3. A polymer blend composition as defined by claim 2, comprising from about 20 to about 35 weight percent polycarbonate, based on the polycarbonate, the terpolymer and the glass fibers.

4. A polymer blend composition as defined by claim 1, comprising from about 10 to about 80 weight percent terpolymer, based on the polycarbonate, the terpolymer and the glass fibers.

5. A polymer blend composition as defined by claim 4, comprising from about 35 to about 75 weight percent terpolymer, based on the polycarbonate, the terpolymer and the glass fibers.

6. A polymer blend composition as defined by claim 1, wherein the polycarbonate comprises an aromatic homopolycarbonate or an aromatic copolycarbonate.

7. A polymer blend composition as defined by claim 6, wherein the polycarbonate is a derivative of bisphenol A.

8. A polymer blend composition as defined by claim 1, wherein the terpolymer comprises from about 4 to about 25 weight percent maleic anhydride.

9. A polymer blend composition as defined by claim 8, wherein the terpolymer comprises from about 5 to about 20 weight percent acrylonitrile.

10. A polymer blend composition as defined by claim 1, wherein the terpolymer includes styrene- acrylonitrile copolymer.

11. A polymer blend composition as defined by claim 1, wherein the glass fibers have an average length of from about 0.05 to about 0.5 inches.

12. A polymer blend composition as defined by claim 1, further including an ABS resin in an amount sufficient to improve the compatibility of the polycarbonate and the terpolymer.

13. A polymer blend composition as defined by claim 12, wherein the ABS resin is included in an amount less than 20 weight percent of the composition.

14. A polymer blend composition as defined by claim 13, wherein the ABS resin is included in an amount of from about 4 to about 19 weight percent.

15. A polymer blend composition as defined by claim 12, wherein the ABS resin comprises at least about 30 weight percent of a diene rubber substrate.

16. A polymer blend composition as defined by claim 15, wherein the ABS resin comprises from about 50 to about 75 weight percent of the diene rubber substrate.