JP2005162910A - Polyester resin composition and molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic polyester resin composition having little temperature dependency and dependency on the concentration of an antistatic agent, and also having excellent electric insulation. <P>SOLUTION: The polyester resin composition comprises (A) 100 pts. wt. polyester resin, (B) 0.05-15 pts. wt. polyalkylene glycol and (C) 0.01-5 pts. wt. organic calcium sulfonate represented by general formula (1) (wherein, R is a 1-32C linear or branched aliphatic hydrocarbon group; n is an integer of 1-3; with the proviso that when n is 2 or 3, two or more Rs contained in one molecule may be the same or different; and Ar is a 6-14C aromatic hydrocarbon group). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a polyester resin composition having antistatic properties and excellent electrical insulation.

Polyester resins are excellent in mechanical properties, electrical properties, heat resistance, and the like, and have recently been used in many applications such as electrical equipment parts and machine parts.
However, while the polyester resin has the above-described excellent characteristics, it has a high electrical resistivity and is easily charged, and thus may cause various obstacles due to static electricity. For example, when a resin molded product is electrostatically charged, it has the disadvantages that dust and dirt adhere to the surface, impair the appearance, reduce the value of the product, cause an electric shock phenomenon, and hinder its handling. Yes. In addition, in electrical / electronic parts, erroneous operation may occur, causing serious functional problems.
In general, antistatic is carried out by lowering the surface resistance of the product, but it is originally required when using polyester resin with antistatic performance as an insulating material for electrical and electronic parts such as small connectors. Anxiety about electrical insulation may occur.

A surface resistance value of about 10 ⁸ Ω is required to prevent dust and dust from adhering, and such a surface resistance value is required for products that do not come into direct contact with wiring such as electric wires, such as housings of electrical products. Even so, the problem of electrical insulation does not occur. However, in the case of a component such as a connector or socket that is in direct contact with the wiring and whose electrical insulation is an important factor, a low surface resistance value of about 10 ⁸ Ω causes anxiety in the electrical insulation. Therefore, as a resin composition for parts such as connectors that require excellent antistatic performance and high electrical insulation, 10 ¹⁰ Ω or more is sufficiently taken into consideration even in a high humidity environment such as 80%. In this case, the surface resistance value is preferably about 10 ¹⁰ to 10 ¹³ Ω.
In addition, in the composition containing the conventional antistatic agent, the surface resistance changes greatly due to slight variations in the concentration of the antistatic agent bleed out on the surface of the molded product, and there is a lack of confidence in the surface resistance value. This was also a headache for electrical and electronic component designers.

Conventionally, as a method for imparting antistatic performance to a polyester resin, various methods for imparting antistatic properties by melting and kneading an antistatic agent into the resin have been proposed. For example, Patent Documents 1 to 4 describe that an aromatic polyester such as polybutylene terephthalate contains various organic sulfonic acid metal salts and polyalkylene glycol.
All of these documents cite many alkali metal salts as examples of organic sulfonic acid metal salts. Among them, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate and the like are stated to be suitable, and it is shown in the Examples that the surface resistance is remarkably reduced with a small amount. However, when an alkali metal salt of organic sulfonic acid is used, the humidity dependency and antistatic agent concentration dependency of the antistatic performance on the surface of the molded product are large, and it has not been possible to solve the problems of electrical and electronic component designers. .
On the other hand, as examples of alkaline earth metal salts of organic sulfonic acids, Patent Document 2 includes the following compounds, and Patent Document 3 includes calcium dodecyl sulfonate, barium dodecyl sulfonate, and magnesium dodecyl benzene sulfonate. Etc. are mentioned.

However, when the organic sulfonic acid moiety is an aliphatic sulfonic acid, the compatibility of the compound with the polyester resin is lowered, so that the surface bleeding becomes remarkable and the sustainability of the antistatic performance becomes insufficient. . Even in the case of an aromatic sulfonic acid, a compound having a carboxylic acid or a hydroxyl group as a substituent is considered to have a problem of promoting the hydrolysis reaction of the polyester resin.
In addition, since metal Mg is a metal having high activity that is also used in a part of the polyester polymerization catalyst, a compound containing Mg may reduce the stability of the resin. Ba salt is insoluble in water. For example, barium sulfonate is used as grease or rust preventive oil, but has no antistatic effect.
Thus, it has been difficult to adjust the surface resistance value of a molded product formed using a polyester resin to an appropriate value.
JP 52-47072 A JP-A-55-58249 JP 61-258860 A JP-A 63-308059

An object of the present invention is to provide a polyester resin composition excellent in electrical insulation, having low antistatic properties, humidity dependency and antistatic agent concentration dependency.

The present invention has been intensively studied in order to solve the above problems, and has been completed by finding that a specific compound is effective among the alkaline earth metal salts of organic sulfonic acid.
That is, the present invention
(A) Polyester resin 100 parts by weight (B) Polyalkylene glycol: 0.05 to 15 parts by weight (C) Calcium organic sulfonate represented by the following general formula (1): 0.01 to 5 parts by weight The present invention resides in a polyester resin composition containing, and a molded product formed using the same.

(In the general formula (1), R represents a linear or branched aliphatic hydrocarbon group having 1 to 32 carbon atoms, and n represents an integer of 1 to 3, provided that n is 2 or 3. In this case, a plurality of R contained in one molecule may be the same or different, and Ar represents an aromatic hydrocarbon group having 6 to 14 carbon atoms.)

The electrical and electronic parts made of the polyester resin composition of the present invention are less likely to cause functional problems such as causing erroneous operations and charging troubles due to electric shock phenomena, and dust and dust are less likely to adhere to the surface due to electrostatic charging. As a result, the product value is increased by obtaining a molded product having stable electrical insulation and excellent appearance, and therefore, it is widely used in many fields such as the electrical and electronic equipment field, the automobile field, and the machine field. Can be used.

Hereinafter, the present invention will be described in detail.
In the present invention, the (A) polyester resin is obtained by polymerizing a dicarboxylic acid or a derivative thereof and a diol.
As the dicarboxylic acid or a derivative thereof, terephthalic acid or a lower alkyl ester thereof is most preferable, and it is preferable to use this as a main component. However, other dicarboxylic acid components may be used in combination as long as the performance of the present invention is not impaired. Examples of other dicarboxylic acid components include phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, and 4,4′-diphenoxyethane. Aromatic dicarboxylic acids such as dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid Aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and other aliphatic dicarboxylic acids, and lower alkyl or glycol esters thereof. . Among these, you may use together 1 type, or 2 or more types.

(A) The diol used as a raw material for the polyester resin is most preferably ethylene glycol or 1,4-butanediol, and is preferably based on this, but other diols within the range not impairing the performance of the present invention. You may use an ingredient together. Examples of other diol components include ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, 1,5-pentanediol, neo Aliphatic diols such as pentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedi Arocyclic diols such as methylol, aromatic diols such as xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, etc. One or two or more of these may be used in combination.
In the (A) polyester resin of the present invention, lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, etc. Monofunctional components such as hydroxycarboxylic acid, alkoxycarboxylic acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, Trifunctional or higher polyfunctional components such as gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol and the like can be used as the copolymerization component.

In order to produce polyester using the dicarboxylic acid or its derivative and diol, a known method is employed. For example, a case where polybutylene terephthalate is produced using a terephthalic acid component and a 1,4-butanediol component will be described as an example. A direct polymerization method in which terephthalic acid and 1,4-butanediol are directly esterified, It is roughly divided into transesterification methods using dimethyl terephthalate as the main raw material. The former is different in that water is produced in the initial esterification reaction, and the latter is produced in the initial transesterification reaction. Direct esterification is advantageous from the viewpoint of raw material costs.
Polyester production methods are broadly classified into batch methods and continuous methods, depending on the raw material supply or the polymer dispensing form. The initial esterification reaction or transesterification reaction is carried out in a continuous operation, and the subsequent polycondensation is carried out in a batch operation. Conversely, the initial esterification reaction or transesterification reaction is carried out in a batch operation, followed by polycondensation. There is also a method of performing the above by continuous operation.

As the polyester resin in the present invention, an aromatic polyester resin is preferable, but a polybutylene terephthalate resin having an appropriate mechanical strength is most preferable. This polybutylene terephthalate resin means a resin in which terephthalic acid accounts for 50 mol% or more of the total dicarboxylic acid component in the monomer, and 1,4-butanediol accounts for 50 mol% or more of the total diol. The terephthalic acid preferably accounts for 80 mol% or more of the total dicarboxylic acid component, and more preferably 95 mol% or more. It is more preferable that 1,4-butanediol occupies 80 mol% or more of the total diol component, and it is even more preferable that 95 mol% or more.
The intrinsic viscosity of the (A) polyester resin of the present invention, represented by polybutylene terephthalate resin, is obtained by using a mixed solvent of 1,1,2,2-tetrachloroethane / phenol = 1/1 (weight ratio) at a temperature. When measured at 30 ° C., it is 0.50 to 3.0. Two or more resins having an intrinsic viscosity of 0.50 to 3.0 may be used in combination.

Specific examples of the (B) polyalkylene glycol used in the present invention include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random or block copolymers thereof. These polyalkylene glycols may have terminal groups such as glycidyl groups, fatty acid esters, aromatic esters, amides, bisphenol compound (eg bisphenol A) residues, diol (eg neopentyl glycol) residues, etc. It may be contained in the main chain. Of these, polyethylene glycol is preferred.
The molecular weight of the (B) polyalkylene glycol in the present invention is preferably 2,000 or more and usually about 20,000 or less. The content of (B) polyalkylene glycol in the composition of the present invention is 0.05 or more, preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight with respect to 100 parts by weight of (A) polyester resin. The amount is usually 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less. If the content is less than 0.05 parts by weight, the antistatic effect cannot be sufficiently improved, and if it exceeds 15 parts by weight, the mechanical properties of the polyester resin tend to be impaired.

The organic sulfonic acid in the present invention is represented by the following general formula (1).

(In the general formula (1), R represents a linear or branched aliphatic hydrocarbon group having 1 to 32 carbon atoms, and n represents an integer of 1 to 3, provided that n is 2 or 3. In this case, a plurality of R contained in one molecule may be the same or different, and Ar represents an aromatic hydrocarbon group having 6 to 14 carbon atoms.)
R in the said General formula (1) is a C1-C32 linear or branched aliphatic hydrocarbon group, Preferably it is C6-C22. Ar is an aromatic hydrocarbon group having 6 to 14 carbon atoms, preferably a phenyl group or a naphthyl group. n is an integer of 1 to 3 representing the number of R, preferably 1 or 2, and more preferably 1.

Specific examples of the organic calcium sulfonate represented by the general formula (1) include, for example, calcium decylbenzenesulfonate, calcium dodecylbenzenesulfonate, calcium stearylbenzenesulfonate, calcium alkylbenzenesulfonate such as calcium octylbenzenesulfonate, Moreover, alkyl naphthalene sulfonic acid calcium salts such as calcium octyl naphthalene sulfonate and calcium dodecyl naphthalene sulfonate, 2,5 dimethyl benzene sulfonic acid, 2,4 dimethyl benzene sulfonic acid and the like can be mentioned.
Of the calcium (C) organic sulfonates of the present invention, calcium dodecylbenzenesulfonate is particularly preferred.

In the present invention, (C) the organic sulfonate calcium may be used alone or in combination. The content of (C) calcium organic sulfonate in the polyester resin composition of the present invention is 0.01 parts by weight or more, preferably 0.03 parts by weight or more, more preferably 100 parts by weight of (A) polyester resin. It is 0.05 parts by weight or more, and is usually 5 parts by weight or less, preferably 4.5 parts by weight or less, more preferably 4.0 parts by weight or less. If it is less than 0.01 part by weight, the antistatic effect is insufficient, and if it exceeds 5 parts by weight, the mechanical properties of the polyester resin composition are significantly lowered. The above range is preferred from the viewpoint of the balance between antistatic properties and mechanical properties.

The polyester resin composition of the present invention may further contain (D) a halogen-based flame retardant, if desired. The halogen-based flame retardant that can be used as the component (D) has a halogen atom in the molecule, and can be selected and used from commonly used known halogen-based flame retardants. In particular, the bromine content is preferably 20% by weight or more, and may be a high molecular compound or a low molecular compound.

(D) Preferred specific examples of the halogen-based flame retardant include, for example, brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, pentabromobenzyl poly Examples include acrylates and brominated imides.

The content of the (D) halogen flame retardant in the polyester resin composition of the present invention is usually 5 parts by weight or more, preferably 7 parts by weight or more, more preferably 8 parts by weight with respect to 100 parts by weight of the (A) polyester resin. The amount is usually 40 parts by weight or less, preferably 35 parts by weight or less, more preferably 25 parts by weight or less. (D) If the halogen-based flame retardant is less than 5 parts by weight, sufficient flame retardancy may not be obtained, and if it exceeds 40 parts by weight, the physical properties, particularly the mechanical strength, are likely to decrease. (D) The blending amount of the halogen-based flame retardant is preferably within the above range from the viewpoint of balance between flame retardancy and physical properties.

In the polyester resin composition of the present invention, an antimony compound or the like as a flame retardant aid may be used in combination. Examples of the antimony compound include antimony trioxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), sodium antimonate, and the like.

The content of the antimony compound is usually 2 parts by weight or more, preferably 3 parts by weight or more, and usually 40 parts by weight or less, preferably 30 parts by weight or less, more preferably 100 parts by weight of the (A) polyester resin. Is 20 parts by weight or less. If the antimony compound is less than 2 parts by weight, sufficient flame retardancy may not be obtained, and if it exceeds 40 parts by weight, the physical properties are likely to deteriorate. The blending amount of the antimony compound is preferably in the above range from the viewpoint of the balance between flame retardancy and physical properties.

When rigidity or dimensional stability is required in the polyester resin composition of the present invention, (E) an inorganic filler may be blended. Examples of the inorganic filler (E) used in the present invention include fibrous, plate-like, granular materials and mixtures thereof. Specifically, fibrous materials such as glass fibers, carbon fibers, mineral fibers, metal fibers, ceramic whiskers, wollastonite; plate-like materials such as glass flakes, mica and talc; silica, alumina, glass beads, carbon black, Well-known things, such as granular materials, such as calcium carbonate, are mentioned. The criteria for these selections depend on the required properties of the product, but for mechanical strength and rigidity, fibrous materials, especially glass fibers, are selected, and when it is important to reduce the anisotropy and warpage of molded products, A material, especially mica, is selected. In addition, an optimum granular material is selected based on an overall balance in consideration of fluidity during molding.

The content of the inorganic filler is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 100 parts by weight or less, preferably 80 parts by weight or less with respect to 100 parts by weight of the (A) polyester resin. is there.

The polyester resin composition of the present invention may contain various known additives and additives as long as they do not impair the properties of the composition, if necessary, in addition to the components (A), (B), (C), (D), and (E). Resins, dyes, pigments and the like may be contained.
Examples of additives include mold release agents such as paraffin wax, polyethylene wax, stearic acid and its salts or esters, silicone oil, etc .; heat stabilizers such as hindered phenols, phosphites, sulfur-containing ester compounds, etc. Crystallization accelerators; ultraviolet absorbers or weather resistance imparting agents; dyes; pigments;
The resin that can be contained is not particularly limited as long as the performance of the resin composition of the present invention is not impaired. For example, polyamide resin such as nylon 6, nylon 66, nylon 12, nylon MXD6; polycarbonate resin; polyphenylene ether resin; Polyacetal resin; Polyphenylene sulfide resin; Styrene resin such as polystyrene, ABS, AS, MS; Acrylic resin; Olefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer; Fluorine resin such as polytetrafluoroethylene, etc. Thermoplastic resin,
Phenolic resin; Melamine resin; Silicone resin; Thermosetting resin such as epoxy resin,
Nylon 6, Nylon 66, Nylon 46, Nylon 610, Nylon 612, Nylon 11, Nylon 12 and the like hard segment and polyether type (for example, polyethylene oxide, polypropylene oxide, polytetramethylene oxide, etc.) A thermoplastic polyamide elastomer having a soft segment composed of a polyester system (for example, poly (ε-caprolactone), polyethylene adipate, polybutylene adipate, polybutylene succinate, etc.); It is composed of α-olefin polymer such as polyethylene and polypropylene, and soft segment is olefin rubber such as EPDM and EPR or butyl rubber, NBR, hydrogenated S Thermoplastic polyolefin elastomer composed of diene rubber such as BR; SBS (styrene / butadiene / styrene block copolymer), SIS (styrene / isoprene / styrene block copolymer), SEBS (styrene / ethylene / butylene / styrene block copolymer) : SBS hydrogenated), SEPS (styrene / ethylene / propylene / styrene block copolymer: SIS hydrogenated) and other elastomers such as thermoplastic polystyrene elastomers,
Etc.

The polyester resin composition of the present invention is obtained by blending and kneading each of the components (A), (B), (C), (D), and (E), and various additive components used as necessary. Can do.
The blending is performed by a commonly used method, for example, a ribbon blender, a Hensell mixer, a drum blender, or the like. Various extruders, Brabender plastographs, lab plast mills, kneaders, Banbury mixers, etc. are used for melt-kneading. The heating temperature at the time of melt kneading is usually 230 to 290 ° C. In order to suppress decomposition during kneading, it is preferable to use the heat stabilizer described above. Each component including an additional component can be supplied to the kneader in a lump or can be supplied sequentially.
In addition, two or more kinds of components selected from each component, including additional components, can be mixed in advance. By adding a fibrous inorganic filler such as glass fiber after the resin is melted from the middle of the extruder, it can avoid crushing and exhibit high characteristics.

The resin composition of the present invention can be produced by various known molding methods such as injection molding, hollow molding, extrusion molding, compression molding, calendar molding, rotational molding, etc., in the electrical / electronic equipment field, automobile field, machine field, medical field. Molded products such as fields can be obtained. The polyester resin composition of the present invention is most effective when subjected to injection molding because of its good fluidity. In the injection molding, it is preferable to control the resin temperature to 240 to 280 ° C.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

“Parts” in the examples represents “parts by weight”.
For the resin compositions of Examples and Comparative Examples, using an injection molding machine (model SH-100) manufactured by Sumitomo Heavy Industries, Ltd., at a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C., a diameter of 10 cm, a thickness A 20 mm mirror plate having a thickness of 2 mm was continuously formed, and the performance was evaluated by the following test method. The results are shown in Table-1 and Table-2.
[Raw materials used in Examples and Comparative Examples]

* Polyester resin (A-1) Polybutylene terephthalate resin (Mitsubishi Engineering Plastics, Novaduran 5020, [η] = 1.20)
(A-2) Polybutylene terephthalate resin (Mitsubishi Engineering Plastics Co., Ltd., Novaduran 5008, [η] = 0.85)
* Polyalkylene glycol (B) polyethylene glycol (manufactured by Sanyo Chemical Industries, PEG6000P molecular weight = 6000)
* Metal salt of sulfonic acid (C-1) calcium dodecylbenzenesulfonate (BC2070M manufactured by Teika Co., Ltd.)
(C-2) Sodium dodecylbenzenesulfonate (BN2070M manufactured by Teika Co., Ltd.)
(C-3) Sodium dodecyl sulfonate (manufactured by Nikko Petrochemical Co., Ltd. Atre AS-1030c)
C-1 and C-2 contain 30% methanol as a solvent. Since methanol is volatilized by blending and melt-kneading, the amount added in Examples and Comparative Examples is a value not containing methanol.
* Halogen flame retardant (D) Brominated epoxy (T5000 manufactured by Sakamoto Pharmaceutical Co., Ltd.)
* Inorganic filler (E) glass fiber (T187 manufactured by Nippon Electric Glass Co., Ltd.)
* Optional component heat stabilizer (Nippon Ciba-Geigy Co., Ltd., trade name “Irganox 1010”)
[Performance evaluation method]

The antistatic property evaluation is performed by measuring the surface resistivity of a test piece (diameter 10 cm, thickness 2 mm) in accordance with JIS K6911 method using an ultra high resistance meter (manufactured by Advantest). went. Twenty test pieces obtained by continuous molding were allowed to stand for 1 day under conditions of a temperature of 23 ° C., a humidity of 50% and 80%, and then the surface resistivity was measured. The average value and the ratio between the highest value and the lowest value of the 20 measured values of the 20 molded pieces were determined.
The greater the change in the average value of the resistance values at 50% and 80%, the greater the humidity dependency of the surface resistance value, and the larger the maximum / minimum value is, the smaller the surface condition of the molded product is. It shows that the resistance value varies greatly depending on the difference.
The surface resistance value is simply expressed as follows in the table. For example, 8 × 10 ¹² is described as 8E12.
[Example 1, Comparative Examples 1 to 4]

From Comparative Examples 1 and 2, the composition containing sodium dodecylbenzene sulfonate and sodium dodecyl sulfonate, which are generally used in the past, has a high humidity dependency, and even a continuously molded specimen has a surface resistance value. There was a variation of 10 times between the maximum and minimum values. In comparison, calcium dodecylbenzenesulfonate was less dependent on humidity and had less variation between molded products.

It can be seen that even in the composition containing glass fiber and flame retardant, the humidity dependency of calcium dodecylbenzenesulfonate and the variation in the surface resistance value between molded products are small.

The molded product made of the polyester resin composition of the present invention is less dependent on the humidity of the surface resistance value, and the resistance value variation between the molded products is small. It is possible to design, and it is difficult to cause functional problems such as erroneous operation and charging troubles due to electric shock phenomenon. Therefore, it can be widely used in many fields such as the electric / electronic equipment field, the automobile field, and the machine field.

Claims (6)

(A) Polyester resin 100 parts by weight (B) Polyalkylene glycol: 0.05 to 15 parts by weight (C) Calcium organic sulfonate represented by the following general formula (1): 0.01 to 5 parts by weight A polyester resin composition comprising:
(In the general formula (1), R represents a linear or branched aliphatic hydrocarbon group having 1 to 32 carbon atoms, and n represents an integer of 1 to 3, provided that n is 2 or 3. In this case, a plurality of R contained in one molecule may be the same or different, and Ar represents an aromatic hydrocarbon group having 6 to 14 carbon atoms.) The polyester resin composition according to claim 1, further comprising (D) a halogen-based flame retardant in an amount of 5 to 40 parts by weight based on 100 parts by weight of the (A) polyester resin. Furthermore, the polyester resin composition of Claim 1 or 2 which contains 3-100 weight part of (E) inorganic filler with respect to 100 weight part of (A) polyester resin. (A) The polyester resin composition as described in any one of Claim 1 thru | or 3 whose polyester resin is a polybutylene terephthalate. The molded article formed using the polyester resin composition as described in any one of Claims 1 thru | or 4. The molded article according to claim 5, which is formed by injection molding.