BLENDS FROM CARBOXY-FUNCTIONALIZED POLYPHENYLENE RESINS AND ETHYLENE-GLYCIDYL METHACRYLATE COPOLYMERS

Abstract: A polyphenylenesulfide composition contains a carboxy functional polyphenylenesulfide resin and an olefin copolymer. The composition exhibits enhanced levels of physical properties. The compositions are useful for making molded articles.

Description: " BLENDS FROM CARBOXY-FUNCTIONALIZED POLYPHENYLENE RESINS AND ETHYLENE-GLYCIDYL METHACRYLATE COPOLYMERS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to polyphenylene sulfide/olefin copolymer blends, and more particularly relates to blends of carboxy functionalized polyphenylene sulfide with olefin copolymer. Description of Related Art Blends of polyphenylene sulfide resin with an olefin copolymer containing (i) an α-olefin such as ethylene and (ii) an ester of α, β-unsaturated carboxylic acid such as glycidyl methacrylate are set forth in European Patent Application 0228268 which teaches treating the polyphenylene sulfide with acid treatments and water treatments to improve the polyphenylene sulfide resins affinity with the olefin copolymer. While blends of polyphenylene sulfide resin and olefin copolymers can exhibit acceptable levels of various properties for certain applications, it is often desirable to enhance levels of particular properties of the blends. Accordingly, one object of the present invention involves providing polyphenylene sulfide/olefin copolymer blends exhibiting improved physical properties. SUMMARY OF THE INVENTION The present invention involves blends of carboxy-functionalized polyphenylene sulfide and olefin copolymers. The blends exhibit improved physical properties such as unnotched Izod impact strengths and percent tensile elongation. DETAILED DESCRIPTION OF THE INVENTION The blends of the present invention contain respective amounts of (a) an carboxy functional polyphenylene sulfide and (b) an olefin copolymer containing 60% to 99.5% by weight of an α-olefin and 0.5% to 40% by weight of a glycidyl ester of an , -unsaturated carboxylic acid. The blends exhibit improved levels of unnotched Izod impact strength. The polyphenylene sulfide polymer can be linear, branched or lightly crosslin ed. Suitable polyphenylene sulfide polymers can be produced, for example, by the methods of Edmonds, et. al., in U.S. Patent No. 3,354,129 and Campbell in U.S. Patent No. 3,919,177. If desired, such polymers can be subjected to mild, partial curing or light crosslinking, as in the method of Rohlfing, U.S. Patent No. 3,717,620, prior to being used in the compositions of this invention. The polymers will generally have crystalline melting points ranging from about 200'C to about 480 g C. A presently preferred polyphenylene sulfide polymer (PPS) has a crystalline melting point ranging from about 250 β C to 300"C. Preferred polyphenylene sulfide polymers have an inherent viscosity in 1-chloronaphthalene at 206 β C and a polymer concentration of 0.4 g/100 ml solution ranging from about 0.1 to 0.6. The polyphenylene sulfide (hereinafter referred to as PPS) used in the present invention is a polymer comprising at least 70 molar %, preferably at least 90 molar %, of recurring units of the structural formula: (I) ^> " s When the amount of said recurring units is less than 70 molar %, the heat resistance is insufficient. PPS polymers include generally those having a relatively low molecular weight prepared by, for example, a process disclosed in the specification of U.S. Patent No. 3,354,129 and essentially linear polymers having a relatively high molecular weight prepared by, for example, a process disclosed in the specification of U.S. Patent No. 3,919,177. The degree of polymerization of the polymers prepared by the process of U.S. Patent No. 3,354,129 can be further increased by heating the same in an oxygen atmosphere or in the presence of a crosslinking agent such as a peroxide after the polymerization. Though PPS prepared by any process can be used in the present invention, an essentially linear polymer having a relatively high molecular weight prepared by the process of said U.S. Patent No. 3,919,177 is preferably used. Thirty (30) molar % or less of the recurring units of PPS can be those of the structural formulae: (ID 0 Though the melt viscosity of PPS used in the present invention is not particularly limited so far as the moldings can be obtained, a melt viscosity of at least 100 poise is preferred from the viewpoint of the toughness of PPS per se and that of 10,000 poise or less is preferred from the viewpoint of the moldability. For the purposes of this invention, it is necessary that the polyphenylene sulfide contain carboxylic acid group. It may be provided in a number of ways. In one method, the polyphenylene sulfide is prepared by the reaction of an alkali metal sulfide with a mixture of dichloroaromatic compounds and/or monochloroaromatic compounds (used as chain termination agents), including at least one such compound which contains the required carboxylic acid group. A second method, disclosed and claimed in copending application Serial No. 07/373,080 filing. is the reaction of a carboxy free polyphenylene sulfide with a disulfide containing carboxylic acid group such as 4,4'-bis(4-carboxy-phthaliπridophenyl) disulfide (chemical structure is shown below). Said reaction typically occurs at temperatures in the range of about 225°C to 375 β C in the melt. The disulfide is most preferably of the formula: ( I I I ) The carboxy functionality is preferably incorporated in the PPS by employing an carboxy disulfide in the reactants. The carboxy disulfide may be of the formula: (IV) wherein is at least 1 and n+m=5; wherein each R 1 is selected from monovalent hydrocarbon radicals and monovalent hydrogen radicals. R may be methyl. Preferably, R 1 is hydrogen. R 2 is a group containing a carboxylic acid and is preferably selected from the group consisting of -C00H and -R 3 -C00H wherein R 3 is a divalent radical selected from the group consisting of C j to C 2 Q alkylene radicals, Cg to C 2Q cycloalkylene radicals, Cg to C 24 arylene radicals, C 7 to C 24 alkylarylene radicals and C 7 to C 24 arylalkylene radicals and divalent phthali idyl radicals. It is expected that carboxy functional linear PPS containing low levels of sodium will exhibit the best overall unnotched Izod impact strengths and percent tensile elongations. The comparison examples provided in this application directed to branched PPS and lightly crosslinked PPS, however, establish the improved properties obtained by employing carboxy functionality in the various PPS resin over similar resins lacking the carboxy functionality. Branching and crosslinking of the PPS can be achieved by an oxidation of the PPS. It is known that polyphenylene sulfides can be "cured" by heating in contact with an oxygen-containing gas (usually air) at temperatures above about 200 β C, resulting in a substantial decrease in melt flow and, apparently, a concomitant increase in molecular weight. While the exact nature of the curing reaction is not known, it appears to involve branching and/or chain extension, which probably occurs thermally or by oxidation of some type. The polyphenylene sulfides employed in the method of this invention are preferably cured before blending with the ethylene-glycidyl methacrylate copolymers. Typical curing conditions are in the solid or liquid state at temperatures in the range of about 250 β C to 350 β C, for time periods of about 2-10 hours. It is anticipated that the carboxy functional PPS should preferably have a carboxylic acid level of at least 5 carboxylic acid milliequivalents per kilogram of PPS, more preferably from 10 to 200 - 7 - carboxylic acid m ll equivalents per kilogram PPS, and most preferably from 20 to 100 carboxylic acid milliequivalents per kilogram PPS. The olefinic copolymers (B) used in the present invention are copolymers of an α-olefin with a glycidyl ester of an α, β-unsaturated acid. The term " -olefin" as used herein means ethylene, propylene, butene-1, etc. Among them, ethylene is preferred. The amount of α-olefin in the olefin copolymer is 60% to 99.5% by weight, preferably 70% to 97% by weight based on the total weight of α-olefin and glycidyl esters of , β -unsaturated acids. The glycidyl esters of the α, @ -unsaturated acids are compounds of the general formula: (V) CH 2 = C - C - 0 - CH 2 - CH - CH 2 I II \/ R 0 0 wherein R represents a hydrogen atom or a lower alkyl group. Examples of the glycidyl esters of α, β -unsaturated acids include glycidyl acrylate, methacrylate and ethacrylate. Among them, glycidyl methacrylate is preferred. The amount of the glycidyl ester of the α, β-unsaturated acid in the olefinic copolymer is 0.5% to 40% by weight, preferably 3% to 30% by weight based on the total weight of α-olefin and glydicyl esters of α, β -unsaturated acids. When this amount is less than 0.5% by weight, no intended effects can be obtained and, on the contrary, when it exceeds 40% by weight, gelation can occur during melt-blending with PPS which can damage the extrusion stability. moldability and mechanical properties of the product. The olefinic copolymer may further be copolymerized with 40% by weight or less of another copolymerizable unsaturated monomer such as vinyl ether, vinyl acetate, vinyl propionate, methyl acrylate, methyl methacrylate, acrylonitrile or styrene. The preferred olefin copolymer is a 90/10 weight ratio ethylene/glycidyl methacrylate copolymer. A suitable copolymer is sold under the trade name Bondfast E ® by Sumitomo Chemical. Fibrous and/or granular reinforcing agent can be incorporated in an amount of 50 parts by weight or less for 100 parts by weight of the total weight of PPS and the olefinic copolymer, if necessary, in the present invention. Usually, the strength, rigidity, heat resistance and dimensional stability of the product can be improved by incorporating 10 to 50 parts by weight of the reinforcing agent. The fibrous reinforcing agents include inorganic and carbonaceous fibers such as glass fibers, shirasu glass fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers and metal fibers. Examples of the granular reinforcing agents include silicates such as wollastonite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, alumina silicate; metal oxides such as alumina and oxides of silicon, magnesium, zirconium and titanium; carbonates such as calcium and magnesium carbonates and dolomite; sulfates such as calcium and barium sulfates; as well as glass beads, boron nitride, silicon carbide, sialon and silica. These granules may be hollow. These reinforcing agents may be used either alone or in the form of a mixture of two or more of them. If necessary, they can be pretreated with a silane or titanium coupling agent. The preferred fibers are glass fibers and, if employed, are preferably at a level of from 5% to 30% by weight based on the total weight of the composition. The carboxy functional polyphenyl sulfide resin is preferably present in the composition at a level of from 50% to 99.5% by weight based on the total weight of the composition, more preferably from 70% to 96% by weight thereof, and most preferably about 94% to 96% by weight thereof; the olefin copolymer is preferably present at a level of from 0.5% to 50% by weight of the composition, more preferably from 4% to 30% by weight thereof, and most preferably about 4% to 6% by weight thereof. The composition may contain reinforcing fibers such as glass fibers at a level of from 1% to about 50% by weight of the composition, or may be free of reinforcing fibers. EXAMPLES The following examples are meant to illustrate the present invention but not limit the scope thereof. Example B is a blend of the PPS of Example A with an olefin copolymer. Example 2 is a blend of the carboxy functional PPS of Example 1 with an olefin copolymer. For examples B and 2, the blends of PPS and olefin copolymer were extruded on a twin-screw extruder at temperatures from 250°C to 350°C. The extrudates were quenched in water, pelletized, dried and molded into test specimens which were then tested. Heat distortion temperatures (HDT) were measured in β F under a load of 264 psi pursuant to ASTM D648; Unnotched Izod Impact strengths (UNI) were measured in ft-lb pursuant to ASTM D256; Notched Izod Impact Strengths (NI) were measured in ft-lb pursuant to ASTM D256; Tensile elongation (TE) was measured as % elongation pursuant to ASTM D638; Tensile Strength was measured in KPSI pursuant to ASTM D638; Flexural Strength was measured in Kpsi pursuant to ASTM D790; and Flexural modulus was measured in Kpsi pursuant to ASTM D790. PPS COMPARATIVE EXAMPLE A The PPS of the comparative example A was made by reacting respective amounts of disodium sulfide and para dichlorophenyl in N-methyl-2-pyrrolidone (NMP) solvent (VI) CH. according to the method of U.S. Patent No. 3,354,129. U.S. Patents 3,354,129; 3,717,620, 3,919,177; and 4,605,732 are incorporated herein by reference. Published European Patent Application 0228268 is incorporated herein by reference. CARBOXY FUNCTIONAL PPS EXAMPLES (EXAMPLE 1) A mixture of 1796 grams of PPS and 18.14 grams of a disulfide of the formula: (VII ) was extruded on a twin-screw extruder at temperatures in the range of 280°C to 300°C. The extrudate was cured at 260 β C in a forced air oven for eight hours. BLENDS OF PPS WITH OLEFIN COPOLYHER (EXAMPLES B The olefin copolymer employed In the following examples was a 90/10 w and glycidyl methacrylate. The percent by weight olefin copolymer listed I copolymer and PPS. The compositions of examples B and 2 are free of gl fillers and fibers. Example B uses the PPS of example A. Example 2 uses t of example 1. c . Note that 3 of 5 of the test bars of example 2 did not break during Unnotched Izod testing thereof. Also note that the tensile elongation of example 2 was greater than the tensile elongation of example B. Note that the carboxylic acid functional PPS of Example 1, when blended with the olefin copolymer, generally provided superior tensile elongation and unnotched Izod impact strength to blends of the PPS of comparative Example A with the olefin copolymer. The PPS of Example 1 is similar to the PPS of Comparative Example A except for the high degree of carboxy functionality of the PPS of Example 1.

Claims: What is claimed: 1. A polyphenylene sulfide composition comprising: (a) an carboxy functional polyphenylene sulfide resin; and (b) an olefin copolymer containing 60% to 99.5% by weight of an α-olefin and 0.5% to 40% by weight of a glycidyl ester of an α, β-unsaturated carboxylic acid. 2. The composition of claim 1 wherein said carboxy functional polyphenylene sulfide resin has a carboxylic acid equivalent level selected from 10 to 200 milliequivalents per kilogram of carboxy functional polyphenylene sulfide resin. 3. The composition of claim 2 wherein said carboxy functional polyphenylene sulfide resin is present at a level of from 50% to 99.5% by weight based on the total weight of the composition; said olefin copolymer being present in said composition at a level of from 0.5% to 50% by weight based on the total weight of the composition. 4. The composition of claim 3 wherein said α-olefin is ethylene, and said ester of α, β-unsaturated carboxylic acid is glycidyl methacrylate. 5. The composition of claim 4 wherein said olefin copolymer is present at a level of from 4% to 30% by weight based on the total weight of the composition. 6. The composition of claim 4 wherein said composition further comprises from 1% to 50% by weight glass fibers based on the total weight of the composition. 7. A polyphenylene sulfide composition comprising: (a) an carboxy functional polyphenylene sulfide present at a level of from 50% to 99.5% based on the total weight of the composition, said carboxy functional polyphenylene sulfide having a carboxylic acid equivalent level of from 10 to 200 carboxylic acid milliequivalents per kilogram of polyphenylene sulfide; (b) an olefin copolymer derived from an α-olefin and a glycidyl ester of an α, β-unsaturated carboxylic acid, said α-olefin being present at a level of from 60% to 99.5% by weight based on the total weight of α-olefin and glycidyl ester of α, -unsaturated carboxylic acid, said ester of α, 3 -unsaturated carboxylic acid being present at a level of from 0.5% to 40% by weight based on the total weight of α-olefin and glycidyl ester of α, 3 -unsaturated carboxylic acid, said olefin copolymer being present in the composition at a level selected from between 0.5% and 50% by weight based on the total weight of the composition. 8. The composition of claim 7 wherein said composition further comprises from 1% to 50% by weight glass fiber based on the total weight of the composition. 9. The composition of claim 7 wherein said α-olefin is ethylene and said glycidyl ester of an α, β-unsaturated carboxylic acid is glycidyl methacrylate. 10. The composition of claim 9 wherein said α-olefin is present at a level of from 70% to 97% by weight based on the total weight of α-olefin and glycidyl ester of , β -unsaturated carboxylic acid. 11. A polyphenylene sulfide composition consisting essentially of: (a) an carboxy functional polyphenylene sulfide present at a level of from 50% to 99.5% based on the total weight of the composition, said carboxy functional polyphenylene sulfide having a carboxylic acid equivalent level of from 10 to 200 carboxylic acid milliequivalents per kilogram of polyphenylene sulfide; (b) an olefin copolymer derived from an α-olefin and a glycidyl ester of an α, 3-unsaturated carboxylic acid, said α-olefin being present at a level of from 60% to 99.5% by weight based on the total weight of α-olefin and glycidyl ester of α, β-unsaturated carboxylic acid, said ester of α, β-unsaturated carboxylic acid being present at a level of from 0.5% to 40% by weight based on the total weight of α-olefin and glycidyl ester of α, β-unsaturated carboxylic acid, said olefin copolymer being present in the composition at a level selected from between 0.5% and 50% by weight of the composition. 12. The composition of claim 1 wherein said carboxy functional polyphenylene sulfide is derived from a carboxy free polyphenylene sulfide and a carboxy functional disulfide.

Inventors: HAN CHOON YOL, HAN, CHOON, YOL
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 1991
Main classification: C08L63
IPC codes: C08L23, C08L63, C08L81