Document v6ZjKJYVDK1jggm6w9v1Kq82R

United States Patent [19] Schlkhting et aL nil 4,022,748 [45| May 10,1977 [54] THERMOPLASTIC POLYESTER MOLDING COMPOSITIONS (75] Inventors: Kari Schllchltag, Bobenheim-Roxheim; Peter Hern, Ludwigshafen; Rolf Wnb, Heidelberg; Clws Cordes, Weuenheun; Haas-Josef Stand, Ludwigshafen, all of Germany [73] Assignee: BASF AlttfeageseBecfcaft, Ludwigshafen, Germany [22] Filed: Sept 5,1975 [21] Appl. No.: 610,651 [30] Foreign Application Priority Data Sept 18, 1974 Germany ........................ 2444584 [52] U.S.CL............................... 260/40 R; 260/873 [51] tat CL1..........................................C0BG 39/10 [58] Fldd of Search........................... 260/40 R, 873 [56] References Cited UNITED STATES PATENTS 3,969,306 7/1976' Bormonetal..................... 260/873 Primary Examiner--Melvyn I. Marquis Assistant Examiner--S. M. Person Attorney, Agent, or Firm--Keil, Thompson & Shurtleff [57] ABSTRACT Thermoplastic polyester molding compositions show ing good impact resistance at both high and relatively low temperatures and containing A. 100 parts by weight of a linear saturated polyester of an aromatic dicarboxylic acid and optionally small portions of aliphatic dicarboxylic acids with saturated aliphatic or cycloaliphatic diols and B. from 1 to 25 parts by weight of a rubber-elastic graft copolymer having a glass temperature below --20 C and C. optionally from 10 to 80 parts by weight of fillers. 6 Claims, No Drawings 4,022,748 1 THERMOPLASTIC POLYESTER MOLDING COMPOSITIONS It is well known to form crystalline shaped articles elastic properties and their glass transition temperature is below --20 C and in particular between --150 and --20 C and preferably between --80 and --30 C. De termination of the glass transition temperature may be from linear saturated polyesters of aromatic dicarbox- 5 carried out by the method proposed by B. Vollmer, ylic acids. Of industrial significance is injection mold "Grundriss der Makromolekularen Chemie", pp. 406 - ing of polyethylene terephthalate and polybutylene terephthalate. Polybutylene terephthalate shows a 410, published by Springer Verlag, Heidelberg, 1962. For example, a rubber-elastic graft copolymer suit much faster rate of crystallization than polyethylene able for use as additive in the process of the invention terephthalate in such processes and it is therefore par- 10 may be prepared starting from a prepolymer (1) which ticularly suitable for the production of shaped articles has itself been prepared from in very short cycle times. The resulting shaped articles exhibit excellent mechanical properties for many appli cations, a high degree of surface hardness, good gloss a. from 10 to 99% by weight of an acrylate of a C,_i5 alcohol, b. from 1 to 90% by weight of a monomer bearing 2 and relatively good impact resistance. However, on 15 olefinic double bonds which are not conjugated and account of the relatively high glass temperature of 75 c. optionally up to 25% by weight of other mono and 60 C, the impact resistance falls relatively steeply mers. at temperatures below 20 C. Thus for many applica This prepolymer (1) is then grafted with the compo tions it is desirable to have polyesters which are impact- nents (2), (3) and (4) described below, i.e. the compo- resistant at relatively high and relatively low ambient 20 nents (2), (3) and (4) are polymerized in the presence temperatures. However, the other mechanical proper of the prepolymer (1). Advantageous graft copolymers ties such as modulus for elasticity, tensile strength at yield and at break should be impaired either not at all are obtained, for example,, by using prepolymers (1) of a. from 10 to 99% w/w and preferably from 30 to or only to an acceptable degree. 98% w/w and more preferably from 50 to 98% w/w of It has been recommended in various places to im 25 an acrylate of an alcohol having from 1 to 10 carbon prove the impact resistance of polyesters by adding atoms and preferably from 4 to 8 carbon atoms, e.g. other polymers. For example, German Published Ap n-butyl acrylate, octyl acrylate or ethylhexyl acrylate; plication No. 1,694,173 describes the addition of co b. from 1 to 90% w/w and more preferably from 2 to polymers of styrene and conjugated aliphatic dienes to 70% w/w and more preferably from 2 to 50% w/w of a improve the impact resistance of linear saturated poly 30 monomer bearing two olefinic double bonds which are esters of aromatic dicarboxylic acids. Other substances not conjugated, for example vinyl cyclohexane, cy- proposed as additives for polyesters are esters of acrylic clooctadiene-1,5 and/or esters derived from unsatu or metbacrylic acid with saturated alcohols (German Published Application No. 1,694,200), copolymers of rated alcohols, e.g. vinyl acrylate, alkyl acrylates, tricyclodecenyl acrylate and/or diallyl phthalate and/or ethylene and acrylates or methacrylates (German Pub 35 c. optionally up to 25% w/w of other conventional lished Application No. 1,694,170), copolymers of a- monomers such as vinyl ethers, vinyl esters, vinyl ha olefins and vinyl esters of saturated aliphatic monocar- lides, and vinyl-substituted heterocyclic compounds boxylic acids (German Published Application No. 1,694,168) and mixtures of copolymers of conjugated such as vinyl pyrrolidone (the percentages given under (a) to (c) totaling 100). aliphatic dienes and acrylates or methacrylates and 40 Component (b) is essential for subsequent grafting. ionic copolymers of a-olefins and salts of a,/3- The double bonds introduced into the prepolymer by unsaturated acids (German Published Application No. component (b) serve (to a degree varying with the 1,694,188). We have now found that advantages molding compo activity) as grafting sites at which further growth of the polymer molecules subsequently takes place. To such sitions based on polyesters may be obtained according 45 prepolymers (1) there are then grafted (per 100 parts to the present invention. These molding compositions of prepolymer): are characterized in that they contain 2. from 10 to 85 parts by weight and in particular A. 100 parts by weight of a linear saturated polyester from 20 to 70 parts by weight of styrene and/or meth of an aromatic dicarboxylic acid and optionally small acrylates and/or methacrylic or acrylic acid and portions of aliphatic dicarboxylic acids and saturated 50 3. optically up to 35 parts by weight of acrylonitrile aliphatic or cycloaliphatic diols, or methacrylonitrile, the amount thereof being advan B. from 1 to 25 parts by weight of a rubber-elastic tageously from 10 to 15% of the styrene, and graft polymer havign a glass temperature below --20 C 4. optionally up to 20 parts by weight of other mono and mers such as acrylates, vinyl esters, vinyl ethers or vinyl C. optionally from 10 to 80 parts by weight of fillers. 55 halides, and vinylsubstituted heterocyclic compounds It has been found, surprisingly, that molding compo such as vinyl pyrrolidone. sitions of this kind exhibit excellent impact resistance It is advantageous for the graft copolymers to show a even at relatively low temperatures. considerable content of polar groups. Advantageously, By graft copolymers we mean products obtained by products are selected which are composed of more polymerization of monomers in the presence of pre- 60 than 10% by weight of methacrylates or acrylates and polymers to cause grafting of a substantial portion of methacrylonitrile or acrylonitrile. If the content of the monomers onto the prepolymer molecules. The methacrylates or acrylates exceeds 70% by weight, it is manufacture of such graft copolymers is known in prin convenient not' to make use of methacrylonitrile or ciple, particular reference being made to R. J. Ceresa, acrylonitrile as building block. "Block and graft copolymers" (Butterworth, London, 65 The manufacture of the prepolymers and of the graft 1962). In principle, ail graft copolymers are suitable for the purposes of the invention, provided they have rubber- copolymers is effected in conventional manner, prefer ably by emulsion polymerization using conventional free-radical initiators, emulsifiers and chain stoppers in 4,022,748 34 aqueous emulsion or dispersion. The manufacture of in the form of rovings or as chopped or milled strands, suitable graft copolymers is described, e.g., in German which fibers may be provided with a suitable size sys Pat. Nos. 1,260,135 and 1,238,207. tem and an adhesion promoter or adhesive system The types mentioned in the Examples below are based on silanes. The amount of reinforcing filler used characterized as follows: Type A has a backbone con 5 is advantageously from 5 to 60% by weight and in par sisting of a copolymer of n-butyl acrylate and the acry late of tricyclodecenyl alcohol, to which branches con ticular from 10 to 40% by weight. However, other fibrous reinforcing materials may be sisting of 75% w/w styrene and 25% w/w acrylonitrile used, e.g. carbon fibers, potassium titanate monocrysare grafted. The degree of grafting is 30% and the parti tai fibers, gipsum fibers, aluminum oxide fibers or as cle diameter of the emulsion polymer is from 200 to 10 bestos. Non-fibrous such as glass spheres, hollow glass 400 /xm. The glass temperature is from --35 to 40 C. spheres or chalk, quartz and natural and calcined kao Type B has a backbone consisting of a copolymer lins are also useful as are combinations of these materi composed of butyl acrylate, butadiene and methyl vinyl als with glass fibers. These fillers may, as in the case of ether. To this backbone there are grafted, at a degree the glass fibers, be provided with a size and/or an adhe of grafting of 25%, branches consisting of 70% w/w of 15 sion promoter or adhesive system. styrene and 30% w/w of acrylonitrile. The particle The preferred linear saturated polyester of aromatic diameter is from 100 to 200 /xm and the glass tempera dicarboxylic acids is polybutylene terephthalate. It is ture is from --55 to --60 C. also possible to use modified polybutylene terephthal- The graft copolymers of types A and B, when used in ates' containing, in addition to terephthalic acid, other amounts of 0.1 to 20% and preferably from 2 to 10%, 20 aromatic or even aliphatic dicarboxylic acids as basic by weight, in a mixture containing polyester molding units, e.g. naphthalene-2,6-dioic acid or adipic acid. It compositions, effect excellent improvement of the im is likewise possible to use modified polyethylene ter- pact resistance even at temperatures of about --40 C. ephthalates containing, in addition to butanediol-1,4, It is not advantageous to add more than 20% by weight other aliphatic diols such as neopentyl glycol, ethylene of said graft copolymers of the polyester molding com 25 glycol and hexanediol-1,6. positions, since although the impact resistance is im The polyesters should have a relative viscosity of proved further, the modulus of elasticity and the tensile from 1.44 to 1.95 and preferably from 1.50 to 1.75 dl/g strength at break are reduced to such an extent that such compositions become inadequate for many appli (as measured on a 0.5% solution in 60:40 phenol/odichlorobenzene at 25 C). cations. 30 Admixture of the powdered graft copolymers, which The high rate of crystallization of polybutylene ter- should have a water content of not more than 0.02%, ephthalates is not diminished by the addition of said may be effected by simply conveying the polyester graft copolymers. However, it may be helpful in certain granules and the graft copolymer and any other addi cases to add substances known to act as nucleating tives used to an extruder by way of bulk metering agents, e.g. calcium carbonate, aluminum silicates and 35 means, in which extruder the polymers are melted and talc. The addition of the nucleating agents may be thoroughly mixed. effected at various stages in the process for manufac On account of the surprisingly good compatibility of turing the polyester molding compositions. For exam the graft copolymers of type A or B, it is also possible ple, the nucleating agent may be added during the to effect mixing without previous extrusion by passing polycondensation stage or it may be added to the poly 40 the mixture through an injection molding machine. In ester together with one of the graft copolymers (A) or this case, the worm of the machine is sufficient to pro (B) and other additives, if used. duce a homogeneous mixture. Additional improvement in the impact resistance is The polyester molding composition should contain a achieved on both unreinforced and reinforced polyes minimum of moisture, preferably less than 0.02% by ters if diisocyanates are added to the polymer mixture 45 weight. in addition to said graft polymers. The content of diiso The proessing stability of the polyesters and particu cyanates may be from 0.1% to 3%, by weight. It is larly of polybutylene terephthalate is not detrimentally particularly advantageous to introduce 4,5-diphenyl affected by the addition of the graft copolymers A or B. methane diisocyanate. Extrusion and injection molding of the polymer mix The polyester molding compositions of the invention 50 ture may take place between 230 and 280 C, the may also contain flameproofing additives based on temperature of die mold being between 50 and 80 C. elementary red phosphorus, phosphorus compounds, The polyester molding compositions of the invention halogen and nitrogen compounds, antimony oxides, produce partially crystalline, dimensionally stable iron oxides, zinc oxide, dyes and pigments, stabilizers shaped articles which are notable for a high impact counteracting thermal, thermal-oxidative and ultravio 55 resistance even at temperatures down to -40 C. The let attack, waxes, lubricants and processing auxiliaries shaped articles show low moisture absorption, high to ensure trouble-free extrusion and injection molding, solvent resistance, a very white color and high surface and also antistatic agents. gloss. The addition of said graft polymers has also been found suitable for increasing the impact resistance of 60 EXAMPLES polyester molding compositions which are reinforced The graft copolymers A or B were mixed in the pro with fillers. portions stated with a polyester of terephthalic acid and Suitable reinforcing fillers are those capable of in butanediol-1,4 having a relative viscosity of 1.65 gl/g creasing the rigidity of the polyesters. Preferred fillers (measured on a 0.5% solution in 60 : 40 phenol/o- are fibrous substances, particularly glass fibers of low- 65 dichlorobenzene at 25 C) at 240 C and the mixture is alkali E-glass having a fiber diameter of from 8 to 14 ^ then granulated. The resulting granules were dried until and a fiber length in the finished injection molding of the moisture content was less than 0.02%. The granules from 0.1 mm to 0.5 mm. The glass fibers may be used were injection molded at a mold temperature of 60 C 4,022,748 56 and the plastics temperature stated to form standard specimens measuring 4X6X50 mm. The impact resis tance of the said specimens was tested at various tem --20 C said copolymer being prepared by polymer izing from 10 to 85 parts by weight of one or more peratures. Since specimens having standard notches as monomers selected from the group consisting of laid down in the impact resistance test using a pendu- 5 lum as described in DIN 53,453 show no great differen tiation in the test results so that the test is not suitable in this form, the test was modified in that a hole having a diameter of 3 mm was drilled in the centre of the 6x50 mm surface of the standard specimens so as to 10 give a double notch. The perforated notched impact resistance ALK was then measured in cm.kg/cm2 using the arrangement described in DIN 53,453. The impact was struck in the longitudinal direction of the hole, the notch effect occuring on both sides. 15 styrene, methacrylic acid, and methacrylates, up to 35 parts by weight of acrylonitrile or methacryionitrile, and up to 20 parts by weight of other monomers se lected from the group consisting of acrylates, vinyl esters, vinyl ethers, vinyl halides, and vinylsubstituted heterocyclic compounds in the pres ence of 100 parts by weight of a prepolymer of a. from 10 to 99% by weight of an acrylate of Ci-u alcohol, and b. from 1 to 90% by weight of a monomer bear TABLE 1 ing 2 olefinic double bonds, and Perforated notched impact resistance of mixtures of polybutylene terephthalate and graft copolymers at various temperaatures c. up to 25% by weight of other monomers se lected from the group consisting of vinyl ethers, vinyl esters, vinyl halides and vinyl-sub Plastics temperature during injection molding: 240 C Graft copolymers ALK (cmkg/cm*) at Example Type weight% 23 C 0 C -20* C 1 __ 2A3 3A6 4AS 5 B3 6 B6 7 B8 35 31 35 36 40 41 51 44 42 40 50 44 51 44 18 37 41 40 37 41 41 stituted heterocyclic compounds. 2. Thermoplastic polyester molding compositions as set forth in claim 1 and containing, as component B, a graft copolymer composed of a. from 30 to 77% by weight of butyl acrylate and/or ethylhexyl acrylate, from 20 to 40% by weight of butadiene, from 1 to 20% by weight of a monomer having two non-conjugated olefinic double bonds and from 3 to 30% by weight of vinyl alkyl ether TABLE 2 having from 1 to 8 carbon atoms in the alkyl, the percentages totaling 100, which basic polymer has Perforated notched impact resistance of mixtures of polybuty lene terephthalate and graft copolymers at various temper atures Plastics temperature during injection molding: 260 C Graft copolymers ALK (cmkg/cm*) at Example type weight% 23' C 0C -20 C -40'C 8_ 9A _ 3 48 53 34 17 39 21 10 A 6 57 u A 8 60 42 26 43 38 12 A 10 66 46 41 13 A 20 14 B 3 15 B . 6 16 B 8 17 B 10 81 53 58 63 68 70 42 38 20 44 27 49 34 54 * 44 18 B 20 84 83 56 been obtained by polymerizing the monomers in aqueous solutions and to which b. from 10 to 50% by weight, based on (a), of styrene 35 or a mixture of styrene and acrylonitrile containing up to 30% by weight of acrylonitrile has been graftpolymerized in emulsion. 3. Thermoplastic polyester molding compositions as set forth in claim 1 and containing, as component B, a graft copolymer composed of a. from 99 to 80% by weigth of at least one acrylate of an alcohol of from 4 to 8 carbon atoms and from 1 to 20% by weight of the acrylate of tricyclodecenyl alcohol or other monomers having at least two separate olefinic double bonds, which basic poly TABLE 3 mer has been produced by polymerizing the mono mers in aqueous emulsion and to which Perforated notched impact resistance of mixtures of polybuty lene terephthalate and graft copolymers at various temper atures b. from 10 to 50% by weight, based on (a), of styrene or a mixture of styrene and acrylonitrile containing 50 up to 40% by weight of acrylonitrile, has been Plastics temperature during injection molding: 280 C Graft copolymers ALK (cmkg/cm*) at Example type weight^ 23 C O' C -20'C 19 _ _ 20 A 3 21 A 6 22 A 8 23 B 3 24 B 6 24 21 28 25 32 33 35 35 28 24 31 28 19 23 33 32 21 25 25 B 8 36 31 27 graft-polymerized in emulsion. 4. Thermoplastic polyester molding compositions as set forth in claim 1 and containing, as fillers, glass fibers having a diameter of from 8 to 14 /zm and a length of from 0.01 to 0.5 mm, glass spheres, potassium titanate monocrystalline fibers or asbestos. 5. Thermoplastic polyester molding compositions as set forth in claim 1 and containing flame-retardant chlorine-containing and/or bromine-containing addi We claim: 1. Thermoplastic polyester molding compositions comprising; A. 100 parts by weight of a linear saturated polyester of an aromatic dicarboxylic acid and B. from 1 to 25 parts by weight of a rubber-elastic graft copolymer having a glass temperature below tives together with antimony oxide, iron oxide or zinc oxide. 6. Thermoplastic polyester molding compositions as set forth in claim 1 and containing flame-retardant additives based on red phosphorus or phosphorus com pounds. *****