GB2311294A

GB2311294A - Poly(phenylene ether) resin compositions

Info

Publication number: GB2311294A
Application number: GB9704612A
Authority: GB
Inventors: Gisbergen Josephus Gerardu Van; Henricus Cornelis M Timmermans
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1996-03-22
Filing date: 1997-03-06
Publication date: 1997-09-24
Also published as: GB9704612D0

Abstract

Thermoplastic rain compositions are provided which comprise a polyphenylene ether rain and a polystyrene rain modified with a combination of an elastomeric block copolymer and an olefinic elastomer. The compositions are substantially, free of delamination and exhibit enhanced ductility.

Description

POLY(PHENYLENE ETHER) RESIN COMPOSITIONS This invention relates to blends of poly(phenylene ether) resins that exhibit enhanced properties, such as improved impact and/or improved flow. The preferred blends include blends of poly(phenylene ether) resins and polystyrene and/or high impact polystyrene to which have been added mixtures of elastomeric di-block copolymers and elastomeric tri-block copolymers with ethylene-propylene type elastomers.

Brief Description of the Related Art Poly(phenylene ether) resins (referred to hereafter as "PPE") are commercially attractive materials because of their unique combination of properties, including, for example, high temperature resistance, dimensional and hydrolytic stability and electrical properties. In order to improve the melt processability of PPE, various additives are commonly utilized in combination with the PPE. Some of the most widely utilized additives have been polymers based on styrene monomer such as crystal polystyrene and nonelastomeric rubber modified polystyrene (commonly referred to as "HIPSt). Examples of blends made with styrene based monomers can be found in U.S. Patent Nos. 3,383,435; 3,685,945; and 3,960,808, all of which are hereby incorporated by reference.

Enhancing the ductility of blends of PPE and polystyrene and/or high impact polystyrene has been a long standing effort and has received considerable attention It has been especially desired to increase the impact resistance of such blends in order to increase their commercial utility in molded article having sharp edges and corners. The notched Izod impact test has been used as a key measure of performance of the blends in such molded articles. Prior efforts to enhance the ductility of these blends have included addition of elastomeric materials to the compositions. Examples of blends having enhanced ductility can be found in U.S. Patent No. 4,196,116 which is hereby incorporated by reference.

The competition between resin compositions for molded part applications at end users has been ever increasing as new resin blends are continually being developed for the marketplace. A result of this competition is a continual effort to enhance even further the physical properties of presently available commercial resin blends such as the blends of PPE and polystyrene and/or high impact polystyrene. It is therefore apparent that a need continues to exist for alternative strategies for enhancing the ductility of blends of PPE and polystyrene and/or high impact polystyrene.

SUMMARY OF THE INVENTION The needs discussed above have been satisfied by the surprising discovery of an improved thermoplastic composition which comprises: (a) a poiy(phenylene ether) resin; (b) a non-elastomeric styrene based resin; and (c) an elastomeric mixture comprising: (i) at least one substantially saturated block copolymer of the A-B type or the A-B-A type, wherein each A is a polymerized vinyl aromatic hydrocarbon block, and B is derived from at least one polymerized conjugated diene; and (ii) at least one olefinic elastomer selected from the group consisting of ethylene propylene rubber and ethylene propyleneaiene rubber.

The description which follows provides further details regarding this invention DETAILED DESCRIPTION OF THE INVENTION PPE, per se, are known polymers comprising a plurality of structural units of the formula (I):

wherein for each structural unit, each Q1 is independently halogen, primary or secondary lower alkyl (e.g., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q2 is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q1. Preferably, each Q1 is alkyl or phenyl, especially C14 alkyl, and each Q2 is hydrogen.

Both homopolymer and copolymer PPE are included. The preferred homopolymers are those containing 26-dimethyl-1,4-phenyiene ether units.

Suitable copolymers include random copolymers containing, for example, such units in combination with 2,3,Strimethyl-1,Sphenylene ether units.

Also included are PPE containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes, as well as coupled PPE in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two PPE chains to produce a higher molecular weight polymer.

The PPE generally have a number average molecular weight within the range of about 3,00040,000 and a weight average molecular weight within the range of about 20,00080,000, as determined by gel permeation chromatography against polystyrene standards. Its intrinsic viscosity is most often in the range of about 0.15-0.6 dl./g., as measured in chloroform at 250C.

The PPE are typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol or 2,3,6 trimethylphenol. Catalyst systems are generally employed for such coupling; they typically contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.

Particularly useful PPE for many purposes are those which comprise molecules having at least one aminoalkyl-containing end group. The aminoalkyl radical is typically located in an ortho position to the hydroxy group. Products containing such end groups may be obtained by incorporating an appropriate primary or secondary monoamine such as di-nbutylamine or dimethylamine as one of the constituents of the oxidative coupling reaction mixture. Also frequently present are 4-hydroxybiphenyl end groups, typically obtained from reaction mixtures in which a by-product diphenoquinone is present, especially in a copper-halide-secondary or tertiary amine system. A substantial proportion of the polymer molecules, typically constituting as much as about 90% by weight of the polymer, may contain at least one of said aminoalkyl-containing and 4-hydroxybiphenyl end groups.

It will be apparent to those skilled in the art from the foregoing that the PPE contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.

The compositions of the present invention also contain at least one nonelastomeric polymer of an alkenyl aromatic compound indicated as component (B). Suitable polymers of this type may be prepared by methods known in the art including bulk, suspension and emulsion polymerization.

They generally contain at least about 25% by weight of structural units derived from an alkenylaromatic monomer of the formula (it):

wherein R8 is hydrogen, lower alkyl or halogen; Z is vinyl, halogen or lower alkyl; and p is from 0 to 5. These resins include homopolymers of styrene, chlorostyrene and vinyltoluene, random copolymers of styrene with one or more monomers illustrated by acrylonitrile, butadiene, a-methylstyrene, ethylvinylbenzene, divinylbenzene and maleic anhydride, and rubbermodified polystyrenes comprising blends and grafts, wherein the rubber is a polybutadiene or a rubbery copolymer of about 98 68% styrene and about 232% diene monomer. These nonelastomeric rubber modified polystyrenes include high impact polystyrene (commonly referred to as HIPS). Nonelastomeric block copolymer compositions of styrene and butadiene can also be used that have linear block, radial block or tapered block copolymer architectures. They are commercially available from such companies as Fina Oil as under the trademark FINACLEAR and Phillips under the trademark K-RESINS.

The amount of the nonelastomeric alkenyl aromatic resin can vary widely depending in part on the ultimate properties desired in the final composition. For example, compositions with an increased amount of PPE will have higher heat resistance but lower melt flow than compositions which have lesser amounts of PPE. Generally, the ratio of nonelastomeric alkenyl aromatic compound to PPE is between about 1 to 4 and about 4 to 1. The preferred range is about 30% to about 70% by weight based on the total weight of the PPE and the nonelastomeric alkenyl aromatic compound.

The compositions of the present invention comprise a mixture of block copolymers and random olefinic copolymers. A particularly useful class of block copolymers are those derived from the monoalkenyl arylene monomers and are commonly referred to as A-B and A-B-A type block copolymers.

These block copolymers can also include tapered and radial block copolymers as well as vinyl aromatic-conjugated diene core-shell graft copolymers.

An especially preferred subclass of vinyl aromatic monomer-derived resins are the block copolymers comprising monoalkenyl arylene (usually styrene) blocks and conjugated diene (e.g., butadiene or isoprene) or olefin (e.g., ethylene-propylene, ethylene-butylene) blocks and represented as A-B and A-B-A block copolymers. The conjugated diene blocks are preferably substantially hydrogenated and these block copolymers are referred to herein as substantially saturated block copolymers of the A-B and A-B-A types.

Especially preferred substantially saturated block copolymers of the A-B and A-B-A types included block copolymers wherein each A is a polymerized vinyl aromatic hydrocarbon block (preferably polystyrene), and B is derived from at least one polymerized conjugated diene.

Suitable A-B type block copolymers are disclosed in, for example, U.S.

Patent Nos. 3,078,254, 3,402,159, 3,297,793, 3,265,765 and 3,594,452 and U.K Patent 1,264,741, all incorporated herein by reference. Examples of typical species of A-B block copolymers include, e.g., polystyrene-polybutadiene (SBR), polystyrene-poly(ethylenebu tylene) (S-EB), polystyrenepoly(ethylenepropylene) (5-EP), polystyrene-polyisoprene and poly(a methylstyrene)-polybutadiene. Such A-B block copolymers are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE, from the Shell Chemical Co. under the trademark KRATON, and from Kuraray under the trademark SEXTON.

Additionally, A-B-A triblock copolymers and processes for their production as well as hydrogenation, if desired, are disclosed in U.S. Patent Nos. 3,149,182, 3,231,635, 3,462,162, 3,287,333, 3,595,942, 3,694,523 and 3,842,029, which are all incorporated herein by reference. Examples of triblock copolymers include polystyrene-polybutadiene-polystyrene (SBS), polystyrene-poly(ethylenebutylene)-polystyrene (SEBS), polystyrenepoly(ethylenepropylene)-polystyrene (SEPS), polystyrene-polyisoprenepolystyrene (SIS), poly(o-methyl-styrene)-polybutadiene-poly(a- methylstyrene) and poly(a-methylstyrene)-polyisoprene-po ly (a- methylstyrene). Particularly preferred triblock copolymers are available commercially from Shell Chemical Co. under the trademarks CARIFLEX and KRATON.

Admixed with the block copolymer or mixture of block copolymers is at least one additional elastomeric material preferably at least one olefinic elastomer selected from the group consisting of ethylene propylene rubber and ethylene-propylene-diene rubber. These olefinic elastomers are typified as comprising predominantly ethylene units, a moderate amount of propylene units and up to about 20 mole percent of non-conjugated diene monomer units. They may also contain reactive groups such as acid, oxazoline, orthoester, epoxy, amine, or anhydride. Many EPDM's and processes for the production thereof are disclosed in U.S. Patent Nos.

2,933,480, 3,000,866, 3,407,158, 3,093,621 and 3,379,701, which are all incorporated herein by reference.

The ratio of olefinic elastomer to the block copolymer or combination of block copolymers can vary widely depending in part on the final properties desired in the overall composition. The mixture of block copolymers and random olefinic copolymers is generally present between about 1 and 25 weight percent based upon the total weight of the PPE and the nonelastomeric alkenyl aromatic resin. Generally, the ratio of olefinic elastomer to block copolymer can vary from about 1 to 20 to about 20:1.

Optimization based at least in part on what the desired properties are for the composition can be readily achieved without additional undue experimentation.

Compositions of the present invention can also include effective amounts of at least one additive selected from the group consisting of antioxidants, flame retardants, drip retardants, dyes, pigments, colorants, reinforcing agents, fillers, stabilizers, antistatic agents, plasticizers and lubricants. These additives are known in the art, as are their effective levels and methods of incorporation. Effective amounts of the additives vary widely, but they are usually present in an amount up to about 50% or more by weight, based on the weight of the entire composition.

The blends of the present invention can be prepared by a variety of methods involving intimate admixing of the materials with any additional additives desired in the formulation. Suitable procedures include solution blending and melt blending. Because of the availability of melt blending equipment in commercial polymer processing facilities, melt processing procedures are generally preferred. Examples of equipment used in such melt compounding methods include: co-rotating and counter-rotating extruders, disc-pack processors and various other types of extrusion equipment It is often advantageous to apply a vacuum to the melt through a vent port in the equipment to remove volatile impurities in the composition.

In some instances, the compounded material exits the extruder through small exit holes in a die and the resulting strands of molten resin are cooled by passing the strands through a water bath. The cooled strands can be chopped into small pellets for packaging and further handling.

The compositions of the present invention are substantially free of other thermoplastic resins such as, for example, polycarbonates, polyamides, polyetherimides, and polysulfones. It should also be clear that improved molded articles prepared from the compositions of the present invention represent an additional embodiment of this invention.

It should also be clear that improved molded articles prepared from the compositions of the present invention represent an additional embodiment of this invention.

All patents cited by reference are incorporated by reference herein.

In order that those skilled in the art will be better able to practice the invention, the following examples are given by way of illustration and not by way of limitation. They are not intended to limit the invention in any aspect EXAMPLES The compositions of Table 1 were extruded on a twin-screw extruder at a temperature of about 28e310"C. The resultant compositions were molded using an injection molding machine using a temperature set of about 280-300 C and a mold temperature of about 90o110 C. Samples of the compositions were also subjected to measurement of notched Izod impact strength according to ISO 180 (employing a sample size of 80 mm by 10 mm by 4 mm), falling dart test (energy to fracture) according to ISO 66034 (using 100 mm diameter by 4 mm disks), E-modulus according to ISO 527 measured at 5 mm/min with a sample 4 mm thick Viscosity was measured at 2800C at a shear rate of 1500 sex4. Delamination was determined by visual inspection.

The materials used in the following compositions were: Polvphenvlene ether (PPE): A poly(2,6-dimethyl- 1,4-phenylene) ether resin having a number average molecular weight of about 16,000, and an intrinsic viscosity in chloroform at 250C of about 0.46 dl/g.

HIPS: A nonelastomeric rubber modified polystyrene resin. The material used was grade 2114 available from Huntsman Chemical Co.

Block copolymers: KRATON < D G-1650: A substantially saturated polystyrene poly(ethylene-butylene)-polystyrene block copolymer, available from Shell Chemical Company.

KRATON2D G-1701: A substantially saturated polystyrene poly(ethylene-propylene) block copolymer, also available from Shell Chemical Company.

EPDM: Ethylene-propylene-diene materials having ethylene/propylene ratios of about 75/25, and containing about 10% diene monomer units. The material used were Buna AP437, available from Huels Co.

The compositions also contained minor amounts of stabilizers. All components are described as parts by weight based, unless otherwise indicated.

Table 1.

Sam le: 1 2 3 4 5 6 7 PPE 30A 3OA 30A 30A 30A 30A 30.4 HIPS 53.5 53.5 53.5 53.5 53.5 53.5 53.5 KG-1701 - - 4.2 1.4 - 7.2 3 KS1650 14 1.4 4.2 7.2 - 3 EPDM 14 8.4 8A 4.8 4.8 6 Properties: Notched Izod 25.8 11.8 29.1 27.3 23.2 26.1 26.7 234C (kJ/M) Notched Izod 112 5.9 17.7 13.8 111 13.2 113 -30 C (kJ/M) Failing dart 65.6 24 50.1 50.8 613 59.0 74.4 23oC E-mod (mPa) 1950 1710 1900 1850 1900 2020 2000 Vicat B/120 ( C) 122 124 127 126 124 126 124 Viscosity 180 189 191 196 193 193 193 280/1500 (Pa.s) delamination no yes no no no no no As seen by the data in Table 1, PPE/HIPS compositions containing olefinic elastomers without a block copolymer have poor impact strength and delaminate (note sample 2). It would be extremely desirable to utilize such olefinic elastomers in PPE compositions due to their low cost, outstanding thermal stability, and wide commercial availability, however, the properties obtained in PPE compositions, as noted by sample 2, precludes their utility. Addition of a A-B, A-B-A, or mixture of A-B and A-B-A block copolymers in combination with at least one olefinic elastomer unexpectedly afforded compositions which were free of delamination and exhibited impact properties that are equal to or exceed those obtained for compositions having only block copolymers as the impact modifier (sample 1). Moreover, compositions containing only 12 parts total impact modifier (samples 5, 6, and 7) which comprised a mixture of block copolymer and olefinic elastomer unexpected afforded physical properties which are also equal to or exceed the properties obtained for a composition containing 14 parts of block copolymer (sample 1). The combination of excellent physical properties and delamination resistance obtained as illustrated by these examples affords commercially useful compositions. The present examples are meant only as illustrations of part of the unexpected properties obtained in PPE compositions utilizing a mixture of block copolymers and olefinic elastomers.

Claims

1. A thermoplastic resin composition comprising: (a) a poly(phenylene ether) resin: (b) a nonelastomeric alkenyl aromatic resin: and (c) an elastomeric mixture comprising: (i) at least one substantially saturated block copolymer of the A-B type or the A-B-A type, wherein each A is a polymerized vinyl aromatic hydrocarbon block, and B is derived from at least one polymerized conjugated diene; and (ii) at least one olefinic elastomer selected from the group consisting of ethylene propylene rubber and ethylene propylene-diene rubber.

2 The thermoplastic resin composition of Claim 1, wherein the ratio of component (a) to component (b) is between about 1:4 and 4:1 parts by weight and the amount of component (c) is between about 1 weight percent and about 25 weight percent based upon the total weight of components (a) and (b).

3. The thermoplastic resin composition of Claim 1 wherein the composition is substantially free of delamination.

4. The thermoplastic resin composition of Claim 1 wherein component (c)(i) is selected from the group consisting of polystyrenepoly(ethylenebutylene)-polystyrene copolymers, polystyrenepoly(ethylenepropylene)-polystyrene copolymers, polystyrene-polyisoprene polystyrene copolymers, polystyrene-poly(ethylenebutylene) copolymers, polystyrene-poly(ethylenepropylene) copolymers, and polystyrenepolyisoprene copolymers.

5. The thermoplastic resin composition of Claim 1 wherein component (b) is selected from the group consisting of polystyrene resins and nonelastomeric rubber modified polystyrene resins.

6. The thermoplastic resin composition of Claim 1 further comprising at least one additive selected from the group consisting of antioxidants, flame retardants, drip retardants, dyes, pigments, colorants, reinforcing agents, fillers, stabilizers, antistatic agents, plasticizers and lubricants.

7. The thermoplastic resin composition of Claim 1 which is substantially free of other thermoplastic resins.

Claim 8. Articles made from the thermoplastic resin composition of Claim 1.

9. A thermoplastic resin composition consisting essentially of: (a) a poly(phenylene ether) resin; (b) a non-elastomeric styrene based resin; and (c) an elastomeric mixture comprising: (i) at least one substantially saturated block copolymer of the A-B type or the A-B-A type, wherein each A is a polymerized vinyl aromatic hydrocarbon block, and B is derived from at least one polymerized conjugated diene; and (ii) at least one olefinic elastomer selected from the group consisting of ethylene propylene rubber and ethylene propyleneaiene rubber.