JPH0684466B2 - Polyester resin composition with excellent impact resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester resin composition having improved physical properties, especially improved moldability such as ejection molding, which has improved impact strength.

[Conventional technology]

Polyethylene terephthalate (hereinafter sometimes referred to as PET) has excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., and is used in many industrial products such as fibers and films. In particular, PET reinforced with an inorganic filler such as glass fiber has been remarkably improved in thermal properties and mechanical properties, and thus has been widely used in applications such as engineering plastics in recent years.

However, PET does not always have sufficient impact resistance of the molded product, and there is often a problem that the molded product is broken during secondary processing of this molded product, transportation of the molded product, and use of the molded product. Compared to poly (1,4-butylene terephthalate), which is the same thermoplastic polyester (hereinafter sometimes abbreviated as PBT), the impact resistance is inferior.

As a method for improving the impact resistance of PET, it is general to compound some kind of elastic weight body into PET.

For example, JP-B-45-26223 discloses a copolymer of vinyl ester of saturated aliphatic monocarboxylic acid and α-olefin as an impact modifier for polyester resin. JP-B-45-26224 discloses a copolymer of an acrylic ester and a conjugated diene as an impact modifier for polyester resin. Japanese Examined Patent Publication (Kokoku) No. 45-26225 discloses an ionomer as an impact modifier for polyester resin. However, it cannot be said that the desired impact strength of the molded product obtained by the above method is sufficiently improved.

Various other methods are known for modifying the impact strength of polyester resins. For example, in JP-A-51-144452, JP-A-52-32045, JP-A-53-117049, etc., a copolymer composed of α-olefin and α, β-unsaturated carboxylic acid glycidyl ester is used as a polyester. A method of blending with a resin is disclosed. In addition to this copolymer, a method of additionally using an ethylene copolymer as a third component is disclosed in JP-A-58-17148 and JP-A-58-17151, in which polyphenylene sulfide is used in combination. The method is
No. 57-92044.

It is hard to say that sufficient impact strength was obtained even with these methods.

Aromatic polycarbonate resin in plastics is well known as the resin with the highest impact resistance.
There have been many examples of attempts to modify the impact resistance of PET by blending with T (Japanese Patent Publication No. 36-14035). In recent patents, for example, US Pat. No. 4,257,937, a combination of a polyacrylate resin and an aromatic polycarbonate resin is disclosed as an impact strength modifier for polyester resin. With this method, a considerably high impact strength can be obtained.
Further, in JP-A-59-161460, when the impact strength of PET is modified with a polyacrylate resin and an aromatic polycarbonate resin, if a certain effective amount of poly (1,4-butylene terephthalate) is used in combination, it becomes even more remarkable. It was shown that the impact resistance was improved. However, the impact strength (I zod impact strength) obtained by this method is close to that of the PBT / polyacrylate resin / aromatic polycarbonate-based resin composition even at the highest value, and it does not reach a value higher than that.

In addition, the present inventors previously disclosed in JP-A-51-207459 that a PET-based polyester was used in combination with a predetermined amount of PBT-based polyester and further modified with a predetermined amount of a metal salt of a polymer having a specific carboxyl group. By doing so, it has been disclosed that the impact strength of the molded product is extremely high.

However, since the composition is obtained by kneading PET-based polyester and PBT-based polyester at a high temperature, transesterification reaction easily occurs, and scraps and the like of the molded product are crushed into granules, which are mixed with the unmolded raw material to obtain the raw material. In the case of recovery and effective utilization, there was an insufficiency such that high impact strength could not be obtained when molded only with unmolded raw material.

Further, in the composition in which the conventional elastic copolymer is blended with the polyester resin, the impact strength was decreased when exposed to high temperature for a long time. Further, there is a problem that a molded product having poor moldability and surface gloss and good releasability cannot be obtained.

[Problems to be solved by discovery] The first object of the present invention is to significantly improve impact strength while maintaining the excellent physical properties of conventional polyethylene terephthalate, and to improve impact resistance when exposed to high temperature for a long time. To provide a polyester resin composition in which the decrease in A second object of the present invention is to provide a polyethylene terephthalate resin composition that gives a molded article having excellent surface gloss and releasability.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the present inventors have modified a copolyester having a specific composition with a metal salt of a copolymer of α-olefin and α, β-unsaturated carboxylic acid. As a result, the impact resistance of the molded product becomes extremely high, and even if these molded products are crushed into granules and mixed with unmolded raw materials to mold, only the unmolded raw materials are molded. Of the polyethylene terephthalate resin composition has a high impact resistance even after being exposed to a high temperature of 150 ° C. for a long time. The inventors have found that (for example, heat resistance and mechanical strength) are sufficiently retained and reached the present invention.

That is, the present invention is (1) (A) a copolyester substantially composed of structural units represented by the following (I) to (IV): (III) O—CH ₂ —CH ₂ —O (IV) O—CH ₂ CH ₂ CH ₂ CH ₂ —O ₂ (wherein R is an aliphatic digalvonic acid having 9 or more carbon atoms and 2 It is a valent group, and n is an integer of 8 to 84.) (I) is bonded to (III) and / or (IV), and (II) is (III) and / or (IV) Are combined, and the total number of moles of (I) and (II) is (III)
Is equal to the total number of moles of (IV) and (II) is 0.2 to 10 moles relative to 100 moles of (I) in the copolyester, and (IV) is CH ₂ CH ₂ CH ₂ CH ₂ O-. The repeating unit of 1 to 20 mol is contained. Copolyester 10
0 parts by weight (B) α-olefin and α, β-unsaturated carboxylic acid 3 to 100 parts by weight of a metal salt of a copolymer of an α-β-unsaturated carboxylic acid and a third vinyl monomer, and a polyester resin composition having excellent impact resistance It is a thing.

Hereinafter, the present invention will be described in detail.

Copolyester (A) used in the present invention
Is a copolymer polyester having dramatically improved brittleness, which is one of the major drawbacks of polybutylene terephthalate. The present inventors have conducted extensive studies for the purpose of improving the brittleness of polyethylene terephthalate and imparting strong toughness, and improved the brittleness by introducing a unit (II) and a unit (IV) into polyethylene terephthalate. I succeeded in doing so. The high impact resistance of the composition of the present invention is based on the fact that the composition contains the copolymer polyester. Copolymer polyester (A)
In the above, the unit represented by (I) is a unit derived from terephthalic acid or an ester-forming derivative thereof, such as dimethyl terephthalate or diethyl terephthalate. The unit (I) may be replaced with a small amount of a unit based on a dicarboxylic acid component other than terephthalic acid or an ester-forming derivative thereof within a range that does not impair the effects of the present invention.

The unit represented by (II) is a unit derived from an aliphatic dicarboxylic acid having 9 or more carbon atoms or an ester-forming derivative thereof. Regarding the carbon number of the aliphatic dicarboxylic acid, the carbon number of the main chain between the carboxyl groups of the dicarboxylic acid is preferably 7 or more (excluding the carbon atoms of the carboxyl group), and the main chain optionally has branching. Or a part of them may form a ring. The number of carbon atoms between carboxyl groups in the aliphatic dicarboxylic acid forming a ring is the smallest. As such an aliphatic dicarboxylic acid having 9 or more carbon atoms, for example, azelaic acid, sebacic acid, decane dicarboxylic acid, dodecane dicarboxylic acid, tetradecane dicarboxylic acid, hexadecane dicarboxylic acid, octadecacin dicarboxylic acid, eicosane carboxylic acid, Examples thereof include dimer acid, hydrogenated dimer acid, and ester-forming derivatives thereof. The aliphatic dicarboxylic acids or their ester-forming derivatives may be used alone or in admixture of two or more. Particularly preferred dicarboxylic acids in the present invention are dimer acids and hydrogenated dimer acids.

The dimer acid in the present invention is produced from an unsaturated fatty acid containing 18 carbon atoms such as linoleic acid and linolenic acid, or a monohydric alcohol ester thereof, and is mainly composed of dimer acid having 36 carbon atoms. However, some monobasic acids and trimer acids are also included. In order to achieve the object of the present invention, it is preferable to use dimer acid having a low content of monobasic acid and trimer acid.

The unit (II) is contained in an amount of 0.2 mol or more and 10 mol or less, preferably 5 mol or less, and more preferably 3 mol or less based on 100 mol of the unit (I). Within this range, the crystallized product of the copolyester (A) exhibits excellent ductility while maintaining high rigidity, and as a result, high impact strength is imparted to the composition of the present invention. If the proportion is less than 0.2 mol, improvement in toughness cannot be sufficiently achieved as in the case of using polytetramethylene glycol alone as a copolymerization component. On the other hand, if the amount exceeds 10 moles, the melting point of the crystallized product is greatly lowered, and the rigidity is impaired, which is not suitable for the purpose of the present invention.

Further, in the present invention, when modified with the above-mentioned proportion of the unit (II), the brittleness of the crystallized polyethylene terephthalate, which is slightly improved by modification with only poly (tetramethylene oxide) glycol, is dramatically improved.
This effect is not achieved with aliphatic dicarboxylic acids having less than 9 carbon atoms. The upper limit of the carbon number of the aliphatic dicarboxylic acid is not particularly limited, but 100 or less is preferably used in terms of practical use. The range of carbon number of the aliphatic dicarboxylic acid more preferably used is 16 to 54.

The unit represented by (III) is a unit derived from ethylene glycol.

The unit represented by (IV) is a unit derived from poly (tetramethylene oxide) glycol. The use of poly (tetramethylene oxide) glycol as a copolymerization component is necessary to improve the brittleness of a substantially non-oriented crystallized product of polyethylene terephthalate. Repeating units in poly (tetramethylene oxide) glycol
CH ₂ CH ₂ CH ₂ CH ₂ —O is 1 mol or more and 20 mol or less, preferably 3 mol or more and 15 mol or less, and more preferably 3 mol or more 10
It is preferably contained in the following ratio. When the copolymerization ratio is low, the brittleness of the polyester terephthalate cannot be improved. As the copolymerization ratio increases, the rigidity of the crystallized product decreases and the melting point also decreases, which is contrary to the object of the present invention. become.

The molecular weight of poly (tetramethylene oxide) glycol should be about 600 to 6,000 (degree of polymerization (n): 8 to 84). Use of poly (tetramethylene oxide) glycol having a molecular weight outside the above range is not preferable because ductility is reduced. A more preferred molecular weight range is about 600
2,000 (degree of polymerization (n): 8 to 28).

In the case of obtaining the copolyester (A) of the present invention, a small amount is representative, for example, glycerin, trimethylolpropane, pentaerythritol, hexanetriol 1,2,6, trimethylolethane, etc. within a range that does not impair the effects of the present invention. Triol or tetraol, benzenetricabonic acid typified by trimellitic acid, trimesic acid, and pyromellitic acid, or benzenetetracarboxylic acid, or a polyvalent hydroxycarboxylic acid to which 3 to 4 hydroxyl groups and carboxyl groups are bonded. A monofunctional monomer such as a polyfunctional monomer such as an acid or an aliphatic monocarboxylic acid such as stearic acid or oleic acid, a benzoic acid, a phenylacetic acid, a diphenylacetic acid, or a β-naphthoic acid may be used in combination.

The copolyester (A) in the present invention is usually produced by a known method used for producing polyester. Generally, a copolyester is produced by heating a mixture of reaction components in the presence or absence of a catalyst under atmospheric pressure or pressure under an inert gas atmosphere. The temperatures employed to carry out these reactions are in the range of 200 ° C to 270 ° C, preferably 230 ° C to 260 ° C.
It is in the range of ° C. After completion of this reaction, the obtained oligomer product is polycondensed. The polycondensation reaction is about 2 at a pressure of 15 mmHg or less, preferably 1 mmHg or less in the presence of a polycondensation catalyst such as a known antimony, titanium, iron, zinc, cobalt, lead, manganese, or germanium catalyst.
It is performed at a temperature in the range of 70 ° C to 300 ° C.

The fatty acid dicarbolic acid having 9 or more carbon atoms, poly (tetramethylene oxide) glycol, or their ester-forming derivative can be added before the ester exchange reaction or during the esterification reaction, but preferably during the condensation reaction. It is preferably added after the reaction or the esterification reaction, that is, in the condensation step.

The intrinsic viscosity of the copolyester (A) used in the present invention, when measured in a 50/50 weight mixed catalyst system of phenol and tetrachloroethane at 30 ° C.,
Preferably about 0.5 or more and about 1.5 or less, more preferably about 0.5.
It is within the range of about 1.0 or less.

In the present invention, a metal salt (B) of a copolymer of α-olefin and α, β-unsaturated carboxylic acid and optionally a third vinyl monomer (hereinafter sometimes referred to as an ionic copolymer) is used. Added to copolyester. The α-olefin which constitutes the ionic copolymer is ethylene, propylene, etc., and the α, β-unsaturated carboxylic acid is acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. Examples of the vinyl monomer include ethyl acrylate and vinyl acetate, and examples of the metal include monovalent to trivalent metals such as sodium,
Those such as potassium, calcium, zinc and aluminum are preferable.

It was found that when an alkali metal such as sodium or potassium is selected as the metal, not only extremely high impact strength is obtained, but also the impact strength does not decrease even after long-term holding at high temperature. According to the research conducted by the present inventors, such a peculiar phenomenon was recognized only when a very special polyester (A) was selected.

It was also found that when zinc was selected as the metal, a resin composition with little coloring was obtained, and the coloring of the composition was little even after holding for a long time at high temperature.

These ionic copolymers include α-olefin and α, β-
It can be produced by copolymerizing an unsaturated carboxylic acid and optionally a vinyl monomer, and then substituting a part or all of the carboxylic acid with a metal salt. Another method for producing an ionic copolymer is α-olefin and optionally a third method.
There is a method in which an α, β-unsaturated carboxylic acid is graft-weighted on the copolymer with the vinyl monomer, and then the metal salt is substituted. Still another production method is to copolymerize α-olefin with α, β-unsaturated carboxylic acid ester and optionally a third vinyl monomer, and then saponify the carboxylic acid ester moiety and then replace it with a metal salt. There is also a manufacturing method. Although the ionic copolymer obtained by any method is adopted in the present invention, among these ionic copolymers, those particularly preferably used in the present invention are ethylene and acrylic acid or It is a metal salt of a copolymer composed of ethylene and methacrylic acid.

Such ionic copolymers are available from many sources. For example, it is sold under the trade name of Himilan by Mitsui Deupon Polychemicals.

In the above ionic copolymer, it is necessary that the carboxylic acid unit (including the salt form) occupied in the copolymer is 1 mol% or more and 30 mol% or less of all the copolymer units. When it is less than 1 mol%, the effect of the present invention, that is, the impact resistance of the polyester resin is not sufficiently improved. 30 mol%
When it is more than the above range, the ionic copolymer cannot be sufficiently kneaded with the polyester in a short time in a molten state. The more preferable range of the carboxylic acid unit ratio in the ionic copolymer used in the present invention is 2 mol%.
It is above 10 mol%.

In the present invention, the ionic copolymer need not have all the carboxyl groups present neutralized by metal ions, but at least 20 mol% of all carboxyl groups have been neutralized by metal ions. It is necessary to have If the neutralization rate is less than 20 mol%, the effect of the present invention that the impact resistance of the polyester resin is improved cannot be sufficiently obtained.
A preferable neutralization rate is 40% or more, and particularly 60 mol% or more.

The neutralization rate is measured by infrared spectrum analysis of the copolymer. That is, it can be measured by the ratio of the νc = o absorption intensity of the carboxy group formed into a salt and the νc = o absorption intensity of the unneutralized carboxyl group.

The content of the component (B) is 3 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the copolyester.
If the compounding amount is too small, the effect of improving the impact resistance of the molded product will be poor, and if it exceeds 100 parts by weight, the mechanical properties of the product will deteriorate.

The above-mentioned copolyester and ionic copolymer,
Usually, it is obtained in the form of powder or particles (pellets, chips). The desired polyester molded article can be produced by melt-molding these while simply mixing, but once the mixture is melt-kneaded to form pellets or chips, the desired molded article is formed from the pellets or chips. It can also be melt-molded. Therefore, in the present invention, the mixture of the copolyester and the ionic copolymer is not only a mixture of the powders or particles of each, but also a mixture of both powders and particles melt-kneaded.

When blending the ionic copolymer in the copolymerized polyester or during melt molding of the mixture of the copolymer polyester and the ionic copolymer, various additives usually added to the polyester, for example, a colorant, A release agent, an antioxidant, an ultraviolet stabilizer, a flame retardant and the like can be added.

As a method for melt-kneading the composition of the present invention, a commonly used method is preferably used, but a twin-screw extruder is particularly preferable.

The composition of the present invention can be manufactured into various molded articles by melt molding methods such as extrusion molding and injection molding. As a molded product obtained by extrusion molding, a fiber-shaped product, a rod-shaped product, a film-shaped product, a sheet-shaped plate-shaped product, a tube-shaped product, a pipe-shaped product, or the like can be produced in any desired shape depending on the shape of the molding die. Further, by cutting such an extrusion-molded product, a melt molding material in the form of chips or particles such as chips, pellets or the like can be obtained. Further, according to the injection molding method, an arbitrary shape can be manufactured depending on the shape of the mold. The molded product obtained by any of the molding methods can be easily made into a desired final molded product by secondary molding such as blow molding, drawing molding or vacuum molding. And, all of these various molded products can obtain extremely high impact strength.

As described above, the composition of the present invention not only gives a molded article having an extremely high impact strength, which has not been predicted with the conventional PET-based polyester resin, but also reduces the impact strength even when exposed to high temperature for a long time. The contribution to the world is great.

Furthermore, when an alkali is selected as the metal salt of the ionic copolymer in the composition of the present invention, the polyester resin is sufficiently crystallized even when injection molding is performed in a comparatively low temperature mold as a PET resin, resulting in mold releasability. Since it gives a molded product with excellent surface properties, it can be said to be a resin with excellent moldability.

Hereinafter, the present invention will be described with reference to examples. In the examples, all parts are by weight unless otherwise specified.

〔Example〕

Reference Example A (Synthesis Example of Copolyester) As a catalyst, antimony trioxide and phosphorous acid were used. After esterification from terephthalic acid and ethylene glycol at 260 ° C., a predetermined amount of aliphatic dicarboxylic acid and Poly (tetramethylene oxide) glycol was added, and polycondensation reaction was carried out under reduced pressure according to a conventional method. The obtained copolymer polyester was taken out from the nozzle in a strand form with a gear pump, cooled with water and made into pellets with a cutter.

The obtained copolyester was dissolved in hexafluoropropanol and the terephthalic acid unit was measured by 500 MHz ¹ H-NMR.
Aliphatic dicarboxylic acid units and poly (tetramethylene oxide) glycol repeating units per 100 moles were analyzed (Table 1).

The obtained copolyester was dissolved in phenol / tetrachloroethane (1: 1 weight ratio) and the intrinsic viscosity was measured (Table 1).

Examples 1 to 9, Comparative Example 1 100 parts of copolymerized polyester (prepared in Reference Example A) thoroughly dried in a hot air drier and a predetermined amount of sodium salt of ethylene / methacrylic acid as an ionic copolymer. (Product name: Himilan 1856, manufactured by Mitsui Polychemicals Co., Ltd.), and Phosphite 168 (= as an antioxidant
(Trade name, Ciba Geigy) is blended in an amount of 1/10 of the used amount of the ionic copolymer, premixed, and then charged into a hopper of a 30 mmφ twin-screw extruder (Plastic Engineering Laboratory Co., Ltd.),
A cylinder temperature of 190-270-280-285 ° C (from the hopper side) was extruded while melt-kneading at an adapter temperature of 285 ° C and a die temperature of 275 ° C to obtain strands, which were cut into pellets.

The pellets were then dried at 120 ° C for 12 hours, held at 280 ° C and sandwiched in a hot press with a gap of 3 mm.
After preheating for 1 minute, pressure was applied for 5 minutes under a pressure of 50 kg / cm ₂ . Then 15
It was pressed with a press kept at 0 ° C. for 4 minutes and then cooled with a cooling press to obtain a sheet of about 3 mm heat in which crystallization was sufficiently promoted. A test piece was cut from the obtained sheet to obtain Izod impact strength (notched, ASTM D25
6) was measured. The results are shown in Table 2.

Due to the presence of the ionic copolymer in an amount of 5 parts by weight or more,
High impact strength was obtained.

The compositions of the present invention obtained by changing the types, molecular weights and blending amounts of the aliphatic dicarboxylic acid and poly (tetramethylene oxide) glycol of the copolyester all showed high impact strength. Also the obtained composition
Table 2 shows the results of measuring the Izod impact strength after standing in an air bath at ℃ for 7 days.

High impact strength was maintained despite long-term exposure to high temperatures. The surface appearance of the molded product was good.

Comparative Examples 2 to 6 When no aliphatic dicarboxylic acid was added during the production of the copolyester (Copolyester G Comparative Example 2), when no poly (tetramethylene oxide) glycol was added (Copolyester H, Comparative Example) 3) or when an excessive amount is added (copolymerized polyester I, comparative example 4), when an aliphatic dicarboxylic acid having a small carbon number is added (copolymerized polyester J, comparative example 5), and an aliphatic dicarboxylic acid is added. In the case of using an excessive amount (Copolyester K, Comparative Example 6), the copolyesters shown in Table 1 were obtained in the same manner as in Reference Example A.

A molded article was obtained using the obtained copolyester in the same manner as in Example 3, and the Izod impact strength was measured. The results are shown in Table 2.

In both cases, it was confirmed that the impact strength after molding was improved by blending the ionic copolymer, but if it is exposed to high temperature for a long time, it may be affected by the impact strength due to local deterioration. The variation was large and the quality was not stable. According to the present invention, the type and amount of the aliphatic dicarboxylic acid in the copolyester, the amount of poly (tetramethylene oxide) glycol used are all within the proper ranges, and are stable only in the case of the composition using the copolyester. It is clear that a high impact strength can be obtained.

Comparative Example 7 A molded product was obtained in the same manner as in Example 3 except that polyethylene terephthalate having an intrinsic viscosity of 0.74 dl / g was used in place of the copolyester, and the impact strength of the molded product was measured. The results are shown in Table 2.

In the case of polyethylene terephthalate which was not subjected to any modification, the impact strength was increased to some extent by blending the ionic copolymer, but the impact strength was remarkably lowered by the long-term exposure to high temperature.

Comparative Example 8 In the same manner as in Example 3 except that an ethylene / ethyl acrylate copolymer (trade name, Yucaron X-190-1, manufactured by Mitsubishi Petrochemical Co., Ltd.) was used instead of the ionic copolymer. A molded product was obtained and the impact strength of the obtained molded product was measured. The results are shown in Table 2.

It was not possible to obtain a high impact strength only by using a polymer which does not form a metal salt.

Examples 10 to 12 The same as Examples 3, 5 and 6 except that a zinc salt of an ethylene / methacrylic acid copolymer (trade name, Himilan 1855, manufactured by Mitsui Chemicals, Inc.) was used as the ionic copolymer. A white molded product having no yellowish color was obtained.
Table 3 shows the impact strength of the obtained molded product.

Further, even after the obtained molded product was left in an air bath at 150 ° C. for 7 days, the molded product showed almost no color.

Comparative Examples 9 to 12 Molded products were obtained in the same manner as in Example 10 except that the type of copolymer polyester was changed. Table 3 shows the impact strength of the obtained molded product. When the type of the copolyester used was different, the impact strength after molding was somewhat high, but the impact strength of the molded article was remarkably lowered by leaving the molded article at high temperature for a long time. In Comparative Example 12 in which polyethylene terephthalate was used instead of the copolyester, the impact strength after molding was also extremely low.

[Effect of the Invention] The polyester resin composition of the present invention imparts extremely high impact resistance to a molding polyethylene terephthalate resin composition, and further retains high impact strength even when exposed to high temperatures for a long time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Yokota, 1621 Sakazu, Kurashiki, Okayama Prefecture, Kuraray Co., Ltd. (72) Inventor Yoshifumi Murata, 2045, Saetsu, Aoyama, Kurashiki, Okayama (72) Teruhisa Kaneda, Kuraray Co., Ltd., a share company at 2045 Saoe Aoeyama Kurashiki City, Okayama Prefecture

Claims (8)

[Claims] 1. A copolymerized polyester (A) consisting essentially of structural units represented by the following (I) to (IV): _{(III) O-CH 2 -CH} 2 -O (IV) O-CH 2 CH 2 CH 2 CH 2 -O n ( where, R represents a divalent excluding a carboxyl group from an aliphatic dicarboxylic acid or 9 carbon atoms And n is an integer of 8 to 84.) (I) is bonded to (III) and / or (IV), and (II) is bonded to (III) and / or (IV). And substantially the total number of moles of (I) and (II) is (III)
Is equal to the total number of moles of (IV) and (II) is 0.2 to 10 moles per 100 moles of (I) in the copolyester, and (IV) is CH ₂ CH ₂ CH ₂ CH ₂ O. Repeating unit is 1
Copolyester 10 contained in a proportion of up to 20 mol
0 parts by weight (B) α-olefin and α, β-unsaturated carboxylic acid 3 to 100 parts by weight of a metal salt of a copolymer of an α-β-unsaturated carboxylic acid and a third vinyl monomer, and a polyester resin composition having excellent impact resistance object. 2. The polyester according to claim 1, wherein R in the structural unit (II) is a divalent group obtained by removing a carboxyl group from at least one aliphatic dicarboxylic acid having 16 to 54 carbon atoms. Resin composition. 3. In the structural unit (II), R represents a carboxyl group from at least one dicarboxylic acid selected from the group consisting of tetradecanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid and hydrogenated dimer acid. The copolyester resin composition according to claim 1, which is a divalent group removed. 4. In the structural unit (II), R is a divalent group obtained by removing a carboxyl group from at least one dicarboxylic acid selected from the group consisting of dimer acid and hydrogenated products thereof. The polyester resin composition according to claim 1. 5. In the structural unit (IV), n is 8 or more,
The polyester resin composition according to any one of claims 1 to 4, which is 28 or less. 6. A method according to claim 1, wherein the component (B) is an alkali metal salt of a copolymer of ethylene and acrylic acid or methacrylic acid and optionally a third vinyl monomer.
The polyester resin composition according to item 5. 7. The polyester resin composition according to claim 1 or 6, wherein the metal salt of component (B) is a sodium salt or a potassium salt. 8. The polyester resin composition according to claim 1, wherein the metal salt of the component (B) is a zinc salt.