Polyester resin composition

Abstract: A polyester resin composition having an improved molding processability and capable of providing molded articles having an improved impact resistance and other excellent properties such as mechanical strength and heat resistance, which comprises (a) a thermoplastic polyester, e.g. polyethylene terephthalate or a modified polyethylene terephthalate, (b) a polymer containing at least one epoxy group per molecule and having a modulus of elasticity of at most 10⁴ kg/cm², e.g. an α-­ olefin/glycidyl ester or ether copolymer, and (c) a copolymer of an α-olefin and an α,β-unsaturated carboxylic acid wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal.

Description: The present invention relates to a thermoplastic polyester resin composition having excellent toughness and mechanical strength, and more particularly to a thermoplastic polyester resin composition capable of providing molded articles having an improved impact resistance and other excellent properties such as tensile strength, elongation and heat resistance, as well as a process for its preparation. A representative thermoplastic polyester resin is polyethylene terephthalate. Polyethylene terephthalate has excellent mechanical properties and excellent chemical properties and, therefore, it has been widely used as material for fibers, films and moldings. However, polyethylene terephthalate has the disadvantages that the rate of crystallization and impact resistance are relatively low. Since the crystallization rate is relatively low, the injection molding must be conducted at a mold temperature higher than 140°C. Comparing with other polyester resins, e.g. polybutylene terephthalate for which the mold temperature in injection molding is about 40°C or higher, polyethylene terephthalate requires a substantially higher mold temperature. It is known to use various kinds of crystallizing accelerators in order to improve the above disadvantages. For instance, JP-B-48-4097 and JP-B-48-4098 propose to incorporate metal salts of organic acids, and JP-B-55-47059 proposes to incorporate a plasticizer and an ionomer. The use of these crystallizing accelerators is effective for lowering the mold temperature in injection molding to a practical level, but the mechanical strength and impact resistance are not sufficiently improved. It has also been proposed to introduce a soft segment to polyethylene terephthalate by copolymerization in order to raise the crystallization rate simultaneously with an improvement in impact resistance. For instance, "Journal of Polymer Science", Vol. 8, 1(1952), discloses a copolymerization with polyethylene glycol. JP-A-61-243854 discloses a copolymerization of polyethylene terephthalate with an addition polymerization product of an alkylene oxide to a polyalkylene glycol or a bisphenol compound. The introduction of a soft segment, particularly polyalkylene glycols, improves the impact resistance of molded articles, but the mechanical strength is lowered. An improvement in the impact resistance of molded articles of thermoplastic resins has been made generally by blending thermoplastic resins with elastomers. To thermoplastic polyester resins, including polyethylene terephthalate, which are one of engineering plastics, the method of blending elastomers has been also applied. It is proposed to blend thermoplastic polyester resins with copolymers of an α-olefin and an α,β-unsaturated carboxylic acid glycidyl ester in an attempt to improve the impact resistance of polyester moldings, as disclosed in JP-B-58-47419 and JP-A-53-117049, 58-17148, 59-115352 and 61-207458. However, these proposals have the disadvantage that no satisfactory improvement in impact resistance is obtained for some polyester resins. No theory about what elastomers are effective for improving the impact resistance has been established. Also, there are cases where if high performance engineering plastics are blended with elastomers having a relatively low elasticity, the impact resistance is improved, but excellent other properties expected as engineering plastics are impaired. Accordingly, it is the present state that experiments must be repeated by combining the objective thermoplastic polyester with various kinds of elastomeric materials in order to look for the suitable elastomeric materials. This also applies to the polyester compositions known from JP-A-59-184 251, WO-A-85/03 718 and EP-A-0 194 808. JP-A-59-184 251 discloses a blend of a polyetherester block copolymer, an olefin/unsaturated carboxylic acid glycidylester copolymer and an ionomer (metal salt of olefin/unsaturated carboxylic acid copolymer). WO-A-85/03 718 discloses a polyester molding composition comprising (A) a polyester matrix resin and (B) an ethylene copolymer, namely an ethylene alkyl(meth)acrylate/glycidyl(meth)acrylate copolymer. It is also disclosed therein that the composition may further contain a sodium or potassium neutralized ethylene/methacrylic acid copolymer. EP-A-0 194 808 discloses a very complex polyester resin composition which comprises at least 9 different components, that is polyethylene terephthalate, a polyester or polyacrylate, an inorganic crystal nucleating agent, an organic compound containing a metal salt of a carboxyl group, a polymer compound containing a metal salt of a carboxyl group, a modifizied polyolefin oder modified olefin elastomer, a copolymer comprising an α-olefin, glycidyl methacrylate or glycidyl acrylate and vinyl acetate, an ester-based plastiziser and a fibres reinforcing material. The modified polyolefin or modified olefin elastomer is based on alicyclic carboxylic acid containing a cis-double bond in the ring. However, the balance between mechanical strength, elongation, impact resistance and heat resistance of thes polyester resin compositions and of the molded articles prepared therefrom is insufficient. Therefore, it is an object of the present invention to provide a thermoplastic polyester resin composition capable of providing molded articles having well-balance excellent properties at a low mold temperature, in particular an excellent balance between mechanical strength, impact resistance, heat resistance and chemical properties. It has been found that the above object can be achieved according to the present invention by a polyester composition which is prepared in a specific manner by using specific components as defined below. According to a first aspect the subject-matter of the present invention is a polyester composition obtainable by a process-comprising melt-blending (1) a polymer containing from 1 to 10 % by mole of units having an epoxy group and having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, (2) 5 to 100 parts by weight of an ionic copolymer prepared of an α-olefin, an α,β-unsaturated carboxylic acid and 0 to 25 % by weight of an alkyl acrylate or methacrylate having a C 1 to C 10 alkyl group or a mixture thereof, wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal, said copolymer having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, and (3) 0 to 66 parts by weight of a thermoplastic polyester, said parts of (2) and (3) being parts by weight per 100 parts by weight of said epoxy-containing polymer (1), and blending 5 to 100 parts by weight of the resulting melt-blended mixture (B) with 100 parts by weight of a thermoplastic polyester (A), said thermoplastic polyester being a polyalkylene terephthalate composed of an acid component containing at least 90 % by mole of terephthalic acid or its derivatives having an ester-forming ability and a glycol component containing at least 90 % by mole of an alkylene glycol having 2 to 10 carbon atoms or the derivatives thereof having an ester-forming ability or a block copolymer of 2 to 90 % by weight of at least one polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability, and the residual by weight of polyethylene terephthalate or a mixture of 100 parts by weight of polyethylene terephthalate and 5 to 500 parts by weight of a block copolymer of 2 to 90 % weight of a polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyorypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and the residual % by weight of polyethylene terephthalate. The polyester composition of the present invention has an improved processability and provides molded articles having well-balanced excellent properties such as mechanical strength, elongation, impact resistance, heat resistance and chemical properties. According to a preferred embodiment of the present invention the epoxy-containing polymer (1) is a polymer having a group selected from the group consisting of glycidyl ether group, glycidyl ester group, glycidyl amino group and a group derived from a reaction of an N-heterocycle-containing compound and epichlorohydrin. According to another preferred embodiment of the present invention the epoxy-containing polymer (1) is a copolymer of an α-olefin and 1 to 30 % by weight of an α,β-unsaturated carboxylic acid glycidyl ester or a polymerizable double bond-containing glycidyl ether. According to another preferred embodiment of the present invention the epoxy-containing polymer (1) is a member selected from the group consisting of an ethylene/glycidyl(meth)acrylate copolymer, an alkyl acrylate/glycidyl(meth)acrylate copolymer, an alkyl acrylate/allyl glycidyl ether copolymer, an ethylene/glycidyl(meth)acrylate/vinyl acetate copolymer, and a graft copolymer of 1 to 90 % by weight of methyl(meth)acrylate with 99 to 10 % by weight of an ethylene/glycidyl(meth)acrylate copolymer. According to a further preferred embodiment of the present invention the copolymer (2) is a copolymer of ethylene and acrylic or methacrylic acid wherein at least 5 % by mole of the acids are neutralized with an alkali metal. According to a second aspect the subject-matter of the present invention is also a process for preparing a polyester composition as defined above comprising melt-blending (1) a polymer containing from 1 to 10 % by mole of units having an epoxy group and having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, (2) 5 to 100 parts by weight of an ionic copolymer prepared of an α-olefin, an α,β-unsaturated carboxylic acid and 0 to 25 % by weight of an alkyl acrylate or methacrylate having a C 1 to C 10 alkyl group or a mixture thereof, wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal, said copolymer having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, and (3) 0 to 66 parts by weight of a thermoplastic polyester, said parts of (2) and (3) being parts by weight per 100 parts by weight of said epoxy-containing polymer (1), and blending 5 to 100 parts by weight of the resulting melt-blended mixture (B) with 100 parts by weight of a thermoplastic polyester (A), said thermoplastic polyester being a polyalkylene terephthalate composed of an acid component containing at least 90 % by mole of terephthalic acid or its derivatives having an ester-forming ability and a glycol component containing at least 90 % by mole of an alkylene glycol having 2 to 10 carbon atoms or the derivatives thereof having an ester-forming ability or a block copolymer of 2 to 90 % by weight of at least one polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and the residual by weight of polyethylene terephthalate or a mixture of 100 parts by weight of polyethylene terephthalate and 5 to 500 parts by weight of a block copolymer of 2 to 90 % weight of a polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and the residual % by weight of polyethylene terephthalate. The melt-blending preferably is carried out at a tempeature of from 150°C to 300°C. According to preferred embodiments of the process of the present invention the epoxy containing polymer (1) is a polymer having a group selected from the group consisting of glycidyl ether group, glycidyl ester group, glycidyl amino group and a group derived from a reaction of an N-heterocycle-containing compound and epichlorohydrin or a copolymer of an α-olefin and 1 to 30 % by weight of an α,β-unsaturated carboxylic acid glycidyl ester or a polymerizable double bond-containing glycidyl ether; or a member selected from the group consisting of an ethylene/glycidyl(meth)acrylate copolymer, an alkyl acrylate/glycidyl(meth)acrylate copolymer, an alkyl acrylate/allyl glycidyl ether copolymer, an ethylene/glycidyl(meth)acrylate/vinyl acetate copolymer, and a graft copolymer of 1 to 90 % by weight of methyl(meth)acrylate with 99 to 10 % by weight of an ethylene/glycidyl(meth)acrylate copolymer. According to a further preferred embodiment of the process of the present invention the copolymer (2) is a copolymer of ethylene and acrylic or methacrylic acid wherein at least 5 % by mole of the acids are neutralized with an alkali metal. Examples of the thermoplastic polyesters (3) used in the present invention are, for instance, a linear saturated polyalkylene terephthalate resin obtained by a reaction of an acid component containing at least 90 % by mole of terephthalic acid or its derivatives having an ester-forming ability and a glycol component containing at least 90 % by mole of a glycol having 2 to 10 carbon atoms, especially an alkylene glycol, or the derivatives thereof having an ester-forming ability, representative examples of which are polyethylene terephthalate and polybutylene terephthalate; a mixture of polyalkylene terephthalate resins such as a mixture of at least 30 % by weight, preferably at least 50 % by weight, of polyethylene terephthalate with polybutylene terephthalate. These thermoplastic polyester resins may be used alone or in admixture thereof. The polyalkylene terephthalate may contain less than 10 % by mole of dicarboxylic acids other than terephthalic acid or its derivatives and less than 10 % by mole of diol compounds other than the alkylene glycol having 2 to 10 carbon atoms or its derivatives. The dicarboxylic acids include, for instance, an aromatic dicarboxylic acid having 6 to 14 carbon atoms, an aliphatio dicarboxylic acid having 4 to 8 carbon atoms, and an alicyclic dicarboxylic acid having 8 to 12 carbon atoms. Typical examples thereof are phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid and cyclohexanedicarboxylic acid. The diol compounds include, for instance, an aliphatic diol having 3 to 10 carbon atoms, an alicyclic diol having 6 to 15 carbon atoms and an aromatic diol having 6 to 15 carbon atoms. Typical examples thereof are propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, cyclohexane-1,4-dimethanol, 2,2-dimethylpropane-1,3-diol, 2,2-bis(4'-hydroxycyclohexyl)propane, 2,2-bis(4'-hydroxyphenyl)propane and hydroquinone. Usually, the polyalkylene terephthalate used in the invention has an intrinsic viscosity of 0.35 to 1.20 (0.5 wt. % concentration in phenol/tetrachloroethane = 50/50 by weight, 25°C). In particular, from the viewpoint of balance between crystallization rate and mechanical strength, polyalkylene terephthalates having an intrinsic viscosity of 0.40 to 0.70, especially 0.45 to 0.65, are preferred. The polyether compounds selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability. The ether units serve to accelerate the crystallization rate and to improve the impact resistance. In particular, in view of high crystallization rate, good heat stability in injection molding and improvement in impact resistance, these polyether compounds are used. The content of the polyether compound in the block copolymer is from 2 to 90 % by weight, preferably 5 to 60 % by weight, more preferably 25 to 50 % by weight. When the content of the polyether compound is less than 2 % by weight, the crystallization rate is not sufficiently increased, and when the content is more than 90 % by weight, the mechanical strength and moisture resistance of molded articles are remarkably lowered. The block copolymers of polyethylene terephthalate and the polyether compound have usually an intrinsic viscosity of 0.35 to 1.20 (0.5 wt. % concentration in phenol/tetrachloroethane = 50/50 by weight, at 25°C). In particular, the block copolymers having an intrinsic viscosity of 0.40 to 1.00, especially 0.50 to 0.80, are preferred from the viewpoint of the balance between the crystallization rate and the mechanical strength. The preparation of the block copolymers may be effected by block-copolymerizing polyethylene terephthalate with the polyether compound in the reactor for synthesis of the polyethylene terephthalate, or may be effected using an extruder to react them. A mixture of polyethylene terephthalate and the polyethylene terephthalate/polyether block copolymer is preferable from the viewpoint of good balance between impact resistance, heat resistance and mechanical strength. The block copolymer is used in an amount of 5 to 500 parts by weight per 100 parts by weight of polyethylene terephthalate. If the amount of the block copolymer is less than 5 parts by weight, the effect of accelerating the crystallization produced by the polyether block in the block copolymer is scarcely expected and the use of such a mixture is substantially the same as the use of polyethylene terephthalate alone. Polymers containing at least one epoxy group per molecule and having a modulus of elasticity in bending of at most 10 4 kg/cm 2 at room temperature (about 23°C) are used in the present invention as the component (b). The epoxy group can attach to the polymers in the form of glycidyl ether group, glycidyl ester group, glycidylamino group, or a group derived from a reaction of an N-heterocycle-containing compound and epichlorohydrin as well as epoxy group. Examples of the epoxy-containing polymer (b) are, for instance, a copolymer of an α-olefin and an α,β-unsaturated carboxylic acid glycidyl ester or a polymerizable double bond-containing glycidyl ether; a polyolefin to which a glycidyl ether group is introduced such as polyolefins having glycidyl ether group at one or both ends; a copolymer of an alkyl acrylate or methacrylate having a C 1 to C 24 alkyl group and glycidyl acrylate or methacrylate or allylglycidyl ether such as an ethyl acrylate/glycidyl acrylate or methacrylate copolymer or a butyl acrylate/allylglycidyl ether copolymer; a graft copolymer of 1 to 90 % by weight of methyl acrylate or methacrylate with 99 to 10 % by weight of ethylene/glycidyl acrylate or methacrylate; both end epoxidated polybutadiene; and epoxidated 1,2-polybutadiene. The epoxy-containing polymer is effective for improving the impact resistance of polyester molded articles so long as at least one epoxy group is present in the molecule. The content of units having epoxy group in the polymer is at least 1 % by mole from the viewpoint of the improvement in impact resistance. When the content of the units having epoxy group is more than 10 % by mole, the impact resistance of molded articles tends to decrease. Also, the epoxy-containing polymer having a modulus of elasticity in bending of more than 10 4 kg/cm 2 at room temperature must be avoided, since the effect of improving the impact resistance is decreased. Preferable epoxy-containing polymers (b) are copolymers of one or more of α-olefins such as ethylene, propylene, 1-butene, 1-hexene and 1-octene and one or more of α,β-unsaturated caboxylic acid glycidyl esters or polymerizable double bond-containing glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, cyclohexene-4-carboxylic acid glycidyl ester and allyl glycidyl ether. The copolymers may contain a minor amount of other copolymerizable monomers, e.g. at most 10 % by mole of vinyl acetate, methyl acrylate or methyl methacrylate. Representative examples of the α-olefin/glycidyl ester or ether copolymers are, for instance, ethylene/glycidyl (meth)acrylate copolymer (e.g. random copolymer of ethylene and glycidyl methacrylate in a ratio of 9 : 1 by weight having a flow rate of 3.0 g/10 min., or ethylene/glycidyl methacrylate copolymer commercially available under the trade mark "Bondfast" 2C made by Sumitomo Chemical Co., Ltd.), a ternary copolymer of ethylene, glycidyl (meth)acrylate and vinyl acetate (e.g. ethylene/glycidyl methacrylate/vinyl acetate copolymer commercially available under the trade mark "Bondfast" 7B made by Sumitomo Chemical Co., Ltd.), ethylene/propylene/glycidyl methacrylate/vinyl acetate copolymer, and ethylene/allyl glycidyl ether copolymer. The content of the glycidyl ester or ether in the copolymer is preferably from 1 to 30 % by weight, especially 5 to 20 % by weight. The content of not less than 1 % by weight is preferred, since the improvement in impact resistance is sufficiently exhibited and the compatibility with polyethylene terephthalate is good. Also, the content of more that 30 % by weight should be avoided, since the fluidity of the resin composition may be decreased. The component (2) used in the present invention is a copolymer of α-olefins and α,β-unsaturated carboxylic acids wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal. They are known as ionomers. Examples of the α-olefin are, for instance, ethylene, propylene, 1-butene, 1-octene, 1-hexene, and the like. The α-olefin may be used alone or in admixture thereof. Examples of the α,β-unsaturated carboxylic acid are, for instance, a monocarboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, and a dicarboxylic acid such as maleic acid or fumaric acid. The carboxylic acids may be used alone or in admixture thereof. Preferably, the content of the α-olefin in the ionic copolymer (2) is at least 50 % by weight, especially from 50 to 95 % by weight. At least 5 % by mole, preferably at least 30 % by mole, more preferably at least 40 % by mole, of the acid groups are neutralized with an alkali metal such as Sodium or potassium. When the degree of neutralization is at least 5 % by mole, the molded articles prepared from the compositions of the present invention have a greatly improved toughness. This improvement is marked particularly when at least 30 % by mole of carboxyl groups are neutralized with sodium ion. The ionic copolymer (2) may contain at most 25 % by weight, preferably at most 10 % by weight, of other copolymerizable monomers, e.g. alkyl (meth)acrylates having a C 1 to C 10 alkyl group such as methyl acrylate, methyl methacrylate or butyl acrylate. From the viewpoint of the improvement in impact resistance of molded articles, it is essential that the copolymer (2) has a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature (about 23°C). The composition of the present invention may contain usual additives which have been generally used for resin compositions, for example, stabilizer, coloring agent, antistatic agent, flame retarder, processing improver, crystallizing agent, a reinforcing material such as glass fiber or carbon fiber, a filler such as talc, mica, glass beads or calcium carbonate. The composition of the present invention can be prepared by known methods, for example, can be prepared into a suitable form such as pellets by melt-blending in an extruder. According to the present invention, the epoxy-containing polymer (1) is melt-blended with 5 to 100 parts by weight, preferably 40 to 80 parts by weight, more preferably 60 to 75 parts by weight, of the ionic copolymer (2) and optionally at most 66 parts by weight of the thermoplastic polyester (3), respectively, per 100 parts by weight of the polymer (1). The blending of the components (1) and (2) and optionally with the component (3) is carried out preferably at a temperature of 150° to 300°C, more preferably 170° to 280°C. When the blending temperature exceeds 250°C, gellation tends to occur. However, even if the composition of the invention is prepared using the gelled material, it provides molded articles having an improved impact resistance. The thus obtained blend is then melt-blended with the polyester (A) in an amount of 5 to 100 parts by weight, preferably 10 to 60 parts by weight, per 100 parts by weight of the polyester (A) under the same condition as above in a known manner, for example, by an extruder, to provide the composition of the present invention. When the amount of the previously formed blend is less than 5 parts by weight per 100 parts by weight of the component (A) to be admixed in the second stage, the impact resistance is not sufficiently improved, and when the amount exceeds 100 parts by weight, the mechanical strength and heat resistance tend to lower. The composition of the present invention can be molded by various methods such as extrusion and injection molding. The obtained moldings have excellent properties such as impact resistance, mechanical strength and heat resistance and, therefore, are suited e.g. as housing for light electrical appliances, automobile parts, and body for power tools. The present invention is more specifically described and explained by means of the following Examples in which all parts and % are by weight unless otherwise noted. In the Examples, the intrinsic viscosity shows the value measured at 25°C with respect to a 0.5 % by weight solution in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane in a ratio of 1 : 1 by weight. Tensile strength Measurement was made according to ASTM D 638. Impact strength by falling weight method The test was made with respect to specimens having a thickness of 3 mm using an egg apple type weigth of 500 g in weight and 3/8 inch in top portion radius R. The 50 % failure height (the height which causes the failure of 50 % of the number of test pieces tested) is shown in the table. Examples 1 to 3 and Comparative Examples 1 to 3 A mixture of 30 % of bisphenol A-ethylene oxide addition polymerization product having an average molecular weight of 1,000 (trade mark "Nissan Uniol" DA-1000, product of Nippon Oil and Fats Co., Ltd.) and 70 % of a polyethylene terephthalate oligomer (about pentamer) was melt-blended under reduced pressure to produce a modified polyethylene terephthalate having an intrinsic viscosity of 0.80 wherein the oligomer was copolymerized with the addition polymerization product (the modified polyethylene terephthalate being hereinafter referred to as "modified PET-1"). To the component (B) (water content: below 0.02 %) shown in Table 1 composed of an epoxy-containing polymer (1), an ionic copolymer (2) and/or a thermoplastic polyester (3), 0.2 part of tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl) propionate]methane, 0.2 part of tris(2,4-di-t-butylphenyl)phosphite and 0.4 part of pentaerythritoltetrakis(β-laurylthiopropionate) were added respectively based on the total weight of the polymers (1), (2) and/or (3). The mixture was melt-blended and extruded at 280°C using an extruder (model PCM-45 made by Ikegai Tekko Kabushiki Kaisha). To the obtained polymer blend dried to a water content of less than 0.02 %, the polyester component (A) (water content: less than 0.02 %) shown in Table 1 was added in the amount shown in Table 1 and admixed. The mixture was melt-blended at 270°C using the extruder, and extruded to give a resin composition while adding 30 parts of glass fibers (diameter: 9.5 µm, length: 3 mm) to the cylinder of the extruder. The obtained resin composition was dried to a water content of less than 0.02 %, and was injection-molded to give test pieces having a size of 120 x 120 x 3 mm. The falling weight impact strength (50 % failure height) of the moldings was measured. The results are shown in Table 1. In Table 1, the abbreviations show the following materials. PET: Polyethylene terephthalate having an inherent viscosity of 0.60 PBT: Polybutylene terephthalate (trade mark "Toray PBT" 1401-X07, made by Toray Industries, Inc.) MPET-1: Modified PET-1 mentioned above MPET-3: Modified polyethylene terephthalate having an intrinsic viscosity of 0.60 prepared by copolymerizing 80 % of a polyethylene terephthalate oligomer with 20 % of a block copolymer wherein 25 % of polyethylene glycol is bonded through ether bond to both ends of 75 % of polypropylene glycol, by melt-blending them under reduced pressure. EGMA: an ethylene/glycidyl methacrylate copolymer (9/1 by weight, flow rate 3.0 g/10 min.) BAAGE: Butyl acrylate/allyl glycidyl ether copolymer having a Mooney viscosity of 30 (allyl glycidyl ether content: 4.5 %) EGMAVA: an ethylene/glycidyl methacrylate/vinyl acetate copolymer (85/10/5 by weight) having a melt index of 7 g/10 min. (ASTM D-1238) EGMAGP: Graft copolymer of 30 parts of methyl methacrylate with 70 parts of a copolymer of 85 % of ethylene and 15 % of glycidyl methacrylate EMANa-1: Random copolymer of 87 % of ethylene, 6.5 % of methacrylic acid and 6.5 % of methacrylic acid sodium salt having an MI of 1.0 g/10 min. (ASTM D-1238) EMANa-2: Random copolymer of 86 % of ethylene, 10 % of methacrylic acid and 4 % of methacrylic acid sodium salt having an MI of 2.8 g/10 min. (ASTM D-1238) EAA: Random copolylmer of 94 % of ethylene and 6 % of acrylic acid In addition to the ingredients used in the Examples, other ingredients can be used in the Examples as set forth in the specification to obtain substantially the same results.

Claims: A polyester composition obtainable by a process comprising melt-blending (1) a polymer containing from 1 to 10 % by mole of units having an epoxy group and having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature (2) 5 to 100 parts by weight of an ionic copolymer prepared of an α-olefin, an α,β-unsaturated carboxylic acid and 0 to 25 % by weight of an alkyl acrylate or methacrylate having a C 1 to C 10 alkyl group or a mixture thereof, wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal, said copolymer having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, and (3) 0 to 66 parts by weight of a thermoplastic polyester, said parts of (2) and (3) being parts by weight per 100 parts by weight of said epoxy-containing polymer (1), and blending 5 to 100 parts by weight of the resulting melt-blended mixture (B) with 100 parts by weight of a thermoplastic polyester (A), said thermoplastic polyester being a polyalkylene terephthalate composed of an acid component containing at least 90 % by mole of terephthalic acid or its derivatives having an ester-forming ability and a glycol component containing at least 90 % by mole of an alkylene glycol having 2 to 10 carbon atoms or the derivatives thereof having an ester-forming ability or a block copolymer of 2 to 90 % by weight of at least one polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and the residual amount by weight of polyethylene terephthalate or a mixture of 100 parts by weight of polyethylene terephthalate and 5 to 500 parts by weight of a block copolymer of 2 to 90 % weight of a polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and the residual % by weight of polyethylene terephthalate. The composition of claim 1, wherein said epoxy-containing polymer (1) is a polymer having a group selected from the group consisting of glycidyl ether group, glycidyl ester group, glycidyl amino group and a group derived from a reaction of an N-heterocycle-containing compound and epichlorohydrin. The composition of claim 1 or 2, wherein said epoxy-containing polymer (1) is a copolymer of an α-olefin and 1 to 30 % by weight of an α,β-unsaturated carboxylic acid glycidyl ester or a polymerizable double bond-containing glycidyl ether. The composition of any of claims 1 to 3, wherein said epoxy-containing polymer (1) is a member selected from the group consisting of an ethylene/glycidyl(meth)acrylate copolymer, an alkyl acrylate/glycidyl(meth)acrylate copolymer, an alkyl acrylate/allyl glycidyl ether copolymer, an ethylene/glycidyl(meth)acrylate/vinyl acetate copolymer, and a graft copolymer of 1 to 90 % by weight of methyl(meth)acrylate with 99 to 10 % by weight of an ethylene/glycidyl(meth)acrylate copolymer. The composition of any of claims 1 to 4, wherein said copolymer (2) is a copolymer of ethylene and acrylic or methacrylic acid wherein at least 5 % by mole of the acids are neutralized with an alkali metal. A process for preparing a polyester composition comprising melt-blending (1) a polymer containing from 1 to 10 % by mole of units having an epoxy group and having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, (2) 5 to 100 parts by weight of an ionic copolymer prepared of an α-olefin, an α,β-unsaturated carboxylic acid and 0 to 25 % by weight of an alkyl acrylate or methacrylate having a C 1 to C 10 alkyl group or a mixture thereof, wherein at least 5 % by mole of the carboxyl groups are neutralized with an alkali metal, said copolymer having a modulus of elasticity in bending of not more than 10 4 kg/cm 2 at room temperature, and (3) 0 to 66 parts by weight of a thermoplastic polyester, said parts of (2) and (3) being parts by weight per 100 parts by weight of said epoxy-containing polymer (1), and blending 5 to 100 parts by weight of the resulting melt-blended mixture (B) with 100 parts by weight of a thermoplastic polyester (A), said thermoplastic polyester being a polyalkylene terephthalate composed of an acid component containing at least 90 % by mole of terephthalic acid or its derivatives having an ester-forming ability and a glycol component containing at least 90 % by mole of an alkylene glycol having 2 to 10 carbon atoms or the derivatives thereof having an ester-forming ability or a block copolymer of 2 to 90 % by weight of at least one polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability and a residual amount of polyethylene terephthalate or a mixture of 100 parts by weight of polyethylene terephthalate and 5 to 500 parts by weight of a block copolymer of 2 to 90 % weight of a polyether compound selected from the group consisting of polyethylene glycol, polypropylene glycol, a polyoxyethylene-polyoxypropylene copolymer, a polyether compound of the formula (2): wherein R 1 is a bivalent hydrocarbon group having 2 to 4 carbon atoms, X is a single bond or a bivalent group selected from -C(CH 3 ) 2 -, -CH 2 -, -S-, -SO 2 - and -CO-, m and n are independently an integer of 5 to 20, and the R 1 groups in respective recurring units may be different from each other, and the derivatives of the polyether compound (2) having an ester-forming ability. The process of claim 6, wherein the melt-blending is carried out at a temperature of from 150°C to 300°C. The process of claim 6 or 7, wherein said epoxy-containing polymer (1) is a polymer having a group selected from the group consisting of glycidyl ether group, glycidyl ester group, glycidyl amino group and a group derived from a reaction of an N-heterocycle-containing compound and epichlorohydrin. The process of any of claims 6 to 8, wherein said epoxy-containing polymer (1) is a copolymer of an α-olefin and 1 to 30 % by weight of an α,β-unsaturated carboxylic acid glycidyl ester or a polymerizable double bond-containing glycidyl ether. The process of any of claims 6 to 9, wherein said epoxy-containing polymer (1) is a member selected from the group consisting of an ethylene/glycidyl(meth)acrylate copolymer, an alkyl acrylate/glycidyl(meth)acrylate copolymer, an alkyl acrylate/allyl glycidyl ether copolymer, an ethylene/glycidyl(meth)acrylate/vinyl acetate copolymer, and a graft copolymer of 1 to 90 % by weight of methyl(meth)acrylate with 99 to 10 % by weight of an ethylene/glycidyl(meth)acrylate copolymer. The process of any of claims 6 to 10, wherein said copolymer (2) is a copolymer of ethylene and acrylic or methacrylic acid wherein at least 5 % by mole of the acids are neutralized with an alkali metal.

Inventors: MIYASHITA SHUNITSU, MOGAMI KENJI, MIYASHITA, SHUNITSU, MOGAMI, KENJI
Applicants: KANEGAFUCHI CHEMICAL IND, KANEGAFUCHI KAGAKU KOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: C08L67
IPC codes: C08L67