JP6325457B2 - Polybutylene terephthalate resin composition - Google Patents

Description

  The present invention relates to a polybutylene terephthalate resin composition. Specifically, the present invention relates to a polybutylene terephthalate resin composition that is excellent in balance in all of heat shock resistance, mechanical strength, and dimensional stability, and is useful for automobile parts, electrical / electronic parts, and the like.

  Polybutylene terephthalate resin is excellent in mechanical properties, electrical properties, other physical and chemical properties, and has good processability, so it can be used as an engineering plastic for a wide range of applications such as automobile parts and electrical / electronic parts. It is used. Among these parts, from the point of function and mechanism, a case is made with polybutylene terephthalate resin, the part body is mounted inside the case, and then it is used as a thermosetting resin such as epoxy resin or silicon resin. There are many products that are manufactured by sealing and insert molding.

  The insert molding method is a molding method in which a metal or the like is embedded in a resin so that the molded product can be used by taking advantage of the properties of the resin and the properties of a metal or inorganic solid (hereinafter abbreviated as metal). This is one of the common molding methods. However, the expansion / contraction rate (so-called linear expansion coefficient) due to temperature change is extremely different between polybutylene terephthalate resin and thermosetting resin or metal, etc. A molded product having a large portion, a molded product having a sharp corner, or the like has many troubles that are cracked immediately after molding or cracked due to a temperature change during use. For this reason, the current situation is that the application and the shape of the molded product are considerably limited.

  Furthermore, the structure of these parts is becoming more and more complex year by year, and if the resin warp deformation is large, the fitting, assembly, and airtightness of the parts may be hindered. There is a strong demand for materials with further improvements and a high degree of dimensional stability. In order to meet such a demand, for example, Patent Document 1 discloses a core-shell type compound having a multilayer structure in which a glassy resin is included in a rubber-like core with respect to a polybutylene terephthalate resin, and a cross section is a longitudinal shape. A polybutylene terephthalate resin composition comprising a predetermined amount of a fibrous filler having a non-circular cross section is disclosed.

JP 2000-265001 A

  In the Example of patent document 1, the glass fiber whose cross section is a bowl shape is used as a fibrous filler which has a non-circular cross section whose cross section is a longitudinal shape. As a result of studies by the present inventors, it has been found that a polybutylene terephthalate resin composition containing such glass fibers is inferior in mechanical strength and dimensional stability, although it is excellent in heat shock resistance.

  The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to obtain a polybutylene terephthalate resin composition excellent in balance among heat shock resistance, mechanical strength, and dimensional stability. It is to provide the technology for.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, if it is a polybutylene terephthalate resin composition containing a fibrous filler having a cross-section with a profile ratio of 1.5 to 3.5, any of heat shock resistance, mechanical strength, and dimensional stability The present inventors have found that it is excellent in balance and have completed the present invention. More specifically, the present invention provides the following.

  (1) A polybutylene terephthalate resin composition containing (A) a polybutylene terephthalate resin and (B) a fibrous filler having a cross-section with a profile ratio of 1.5 to 3.5.

  (2) The polybutylene terephthalate resin composition according to (1), wherein the cross section of the component (B) is oval.

  (3) The polybutylene terephthalate resin composition according to (1) or (2), wherein the component (B) is glass fiber.

  (4) The polybutylene terephthalate resin composition according to any one of (1) to (3), further comprising (C) a carbodiimide compound.

  (5) The polybutylene terephthalate resin composition according to any one of (1) to (4), further comprising (D) an elastomer.

  (6) A molded product obtained by molding the polybutylene terephthalate resin composition according to any one of (1) to (5).

  (7) The molded product according to (6), which is an insert molded product obtained by insert molding the polybutylene terephthalate resin composition and a metal or an inorganic solid.

  According to the present invention, it is possible to obtain a polybutylene terephthalate resin composition that is excellent in balance among heat shock resistance, mechanical strength, and dimensional stability.

FIG. 1 is a diagram showing a cross-section of a fibrous filler having a cross-section with an odd-shape ratio of a / b and an oval shape. FIG. 2 is a diagram showing a cross-section of a fibrous filler having a cross-section with an irregularity ratio of a / b and a shape of a bowl. FIG. 3 is a graph showing the relationship between the amount of glass fiber added to the polybutylene terephthalate resin composition and the heat shock life. In addition, glass fiber addition amount is a value when the addition amount of polybutylene terephthalate resin is 100 mass parts.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments.

<Polybutylene terephthalate resin composition>
The polybutylene terephthalate resin composition of the present invention contains (A) a polybutylene terephthalate resin and (B) a fibrous filler having a cross-section with a profile ratio of 1.5 to 3.5. Hereinafter, each component contained in the polybutylene terephthalate resin composition will be described.

[(A) Polybutylene terephthalate resin]
The (A) polybutylene terephthalate resin (hereinafter sometimes referred to as PBT resin), which is the base resin of the polybutylene terephthalate resin composition according to the present invention, is at least terephthalic acid or an ester-forming derivative thereof (such as a lower alcohol ester). And a polybutylene terephthalate-based resin obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol having at least 4 carbon atoms (1,4-butanediol) or an ester-forming derivative thereof. (A) The PBT resin is not limited to a homo PBT resin, but may be a copolymer (copolymerized PBT resin) containing 60 mol% or more (particularly about 75 to 95 mol%) of a butylene terephthalate unit. The polybutylene terephthalate resin as component (A) can be used alone or in combination of two or more.

In the copolymerized PBT resin, as dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives, for example, aromatic dicarboxylic acid components (isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, etc.) ₆ -C ₁₂ aryl dicarboxylic acid), aliphatic dicarboxylic acid component (e.g., succinic acid, adipic acid, azelaic acid, _C 4 _{-C 16} alkyl dicarboxylic acid such as sebacic acid, _C 5 _{-C 10} cycloalkyl such as cyclohexane dicarboxylic acid Examples thereof include dicarboxylic acids and the like, or ester-forming derivatives thereof. These dicarboxylic acid components can be used alone or in combination of two or more. Preferred dicarboxylic acid components (comonomer components) include aromatic dicarboxylic acid components (especially C ₆ -C ₁₀ aryl dicarboxylic acids such as isophthalic acid), aliphatic dicarboxylic acid components (especially C such as adipic acid, azelaic acid, sebacic acid, etc.) ₆ -C ₁₂ alkyl dicarboxylic acids) are included.

In the copolymerized PBT resin, examples of the glycol component (comonomer component) other than 1,4-butanediol include aliphatic diol components [for example, alkylene glycol (ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene, etc.). glycol, hexamethylene glycol, neopentyl glycol, _C 2 _{-C 10} alkylene glycols such as 1,3-octanediol, diethylene glycol, triethylene glycol, polyoxy _C 2 -C ₄ alkylene glycol such as dipropylene glycol, etc.), cyclohexane dimethanol Alicyclic diols such as methanol and hydrogenated bisphenol A], aromatic diol components [aromatic alcohols such as bisphenol A and 4,4-dihydroxybiphenyl, C of bisphenol A ₂ -C ₄ alkylene oxide adduct (e.g., ethylene oxide 2 mol adduct of bisphenol A, propylene oxide 3 mol adduct of bisphenol A, etc.), etc.], or the like thereof ester-forming derivatives. These glycol components can also be used alone or in combination of two or more. Preferred glycol components (comonomer components) include aliphatic diol components (particularly polyoxy C ₂ -C ₃ alkylene glycols such as C ₂ -C ₆ alkylene glycol and diethylene glycol, and alicyclic diols such as cyclohexane dimethanol). .

  Any of the homo PBT resin or copolymer PBT resin produced by polycondensation using the compound as a monomer component can be used as the component (A) of the present invention. The homo PBT resin and copolymer PBT resin can be used alone or in admixture of two or more. Further, the combined use of an unmodified PBT resin (homo PBT resin) and a copolymerized PBT resin is also useful. As the PBT resin, a thermoplastic branched PBT resin belonging to the category of the copolymerized PBT resin can also be used. This is a polyester resin mainly composed of so-called polybutylene terephthalate or butylene terephthalate monomer and having a branched structure by reaction with a polyfunctional compound. Polyfunctional compounds include aromatic polycarboxylic acid components (trimesic acid, trimellitic acid, pyromellitic acid and alcohol esters thereof), polyol components (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc.) Can be illustrated.

[(B) Fibrous filler having a cross section with an irregularity ratio of 1.5 to 3.5]
In the polybutylene terephthalate resin composition according to the present invention, (B) a fibrous filler having a cross-section with a profile ratio of 1.5 to 3.5 is used as a reinforcing agent, and the heat resistance of the polybutylene terephthalate resin composition is as follows. Shock resistance, mechanical strength, and dimensional stability can be improved in a balanced manner. The fibrous filler of the component (B) is considered to be aligned side by side in the polybutylene terephthalate resin composition according to the present invention, and the molding shrinkage of the molded product obtained from the polybutylene terephthalate resin composition and By reducing the linear expansion coefficient, it is estimated that heat shock resistance, mechanical strength, and dimensional stability can be improved in a balanced manner. (B) The fibrous filler of a component can be used individually by 1 type or in combination of 2 or more types.

  In the present specification, the “cross section” refers to a cross section perpendicular to the major axis direction of the fibrous filler. Further, the “profile ratio” refers to the ratio of the major axis to the minor axis (major axis / minor axis) in the cross section of the fibrous filler. When the deformed ratio varies along the long axis direction of the fibrous filler, a value obtained by averaging the deformed ratios along the long axis direction is used. In the fibrous filler of the component (B), the profile ratio of the cross section is usually 1.5 to 3.5, preferably 1.7 to 3.0, more preferably 1.9 to 2.5. When the deformed ratio is less than 1.5, the polybutylene terephthalate resin composition is likely to deteriorate in dimensional stability due to warpage. When the deformed ratio is more than 3.5, the heat shock resistance of the polybutylene terephthalate resin composition is hardly improved.

  (B) Although the cross-sectional shape of the fibrous filler of a component is not specifically limited as long as the cross-sectional deformation ratio is 1.5-3.5, a convex shape is preferable. The convex shape refers to a shape that is not a shape having a recessed portion (for example, a bowl shape). Examples of the convex shape include, for example, oval, elliptical, oval, and polygonal shapes, and in particular, all of heat shock resistance, mechanical strength, and dimensional stability are excellent in a well-balanced manner. Because of this, an oval shape is preferable. In this specification, an oval refers to a shape composed of two line segments and two curves (for example, an arc, an elliptical arc, and other curves) that connect the two line segments. As shown in FIG. 1, the shape which consists of two parallel line segments which have the same length, and two semicircular arcs which connect these two line segments is mentioned. In FIG. 1, a represents the major axis, b represents the minor axis, and the profile ratio is calculated as a / b.

  As the fibrous filler of component (B), glass fiber, asbestos fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and further stainless steel , Metal fibrous materials such as aluminum, titanium, copper, and brass. A typical fibrous filler is glass fiber or carbon fiber, and glass fiber is particularly preferable. In using these fibrous fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary.

  Although the length of the fibrous filler of (B) component is not specifically limited, Preferably it is 2.0-5.0 mm, More preferably, it is 2.5-4.0 mm. Further, the major axis and minor axis of the cross section of the fibrous filler of the component (B) are not particularly limited, but the major axis is preferably 10 to 26 μm, more preferably 12 to 20 μm, and the minor axis is preferably 5 It is ˜13 μm, more preferably 6 to 10 μm.

  The blending amount of the component (B) in the polybutylene terephthalate resin composition is preferably 20 parts by mass or more and 150 parts by mass or less, more preferably 30 parts by mass or more and 130 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. It is 40 mass parts or more and 110 mass parts or less still more preferably. When the blending amount of the component (B) is in the above range, it is easy to improve the heat shock resistance, mechanical strength, and dimensional stability of the polybutylene terephthalate resin composition in a balanced manner, and particularly heat shock resistance. Tends to be stable and excellent regardless of the amount of component (B).

  The polybutylene terephthalate resin composition of the present invention may contain a fibrous filler other than the component (B), but the fibrous filler other than the component (B) and the fibrous filler other than the component (B). The ratio of the fibrous filler of the component (B) to the total with the agent is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and 90 to 100% by mass. Particularly preferred. When the proportion of the fibrous filler of component (B) is within the above range, the dimensional stability of the polybutylene terephthalate resin composition is likely to be improved.

[(C) Carbodiimide compound]
The polybutylene terephthalate resin composition of the present invention may contain (C) a carbodiimide compound. (C) By containing a carbodiimide compound, the heat shock resistance of the polybutylene terephthalate resin composition can be further improved. (C) A carbodiimide compound can be used individually by 1 type or in combination of 2 or more types.

  The (C) carbodiimide compound used in the present invention is a compound having a carbodiimide group (—N═C═N—) in the molecule. As the carbodiimide compound, any of an aliphatic carbodiimide compound having an aliphatic main chain, an alicyclic carbodiimide compound having an alicyclic main chain, and an aromatic carbodiimide compound having an aromatic main chain can be used. In view of the above, it is preferable to use an aromatic carbodiimide compound.

  Examples of the aliphatic carbodiimide compound include diisopropylcarbodiimide and dioctyldecylcarbodiimide, and examples of the alicyclic carbodiimide compound include dicyclohexylcarbodiimide.

  Examples of aromatic carbodiimide compounds include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, N-triyl-N′-phenylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, and di-p-. Hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, p-phenylene-bis-di-o-triylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, ethylene-bis-diphenyl Mono- or dicarbodiimide compounds such as rubodiimide and poly (4,4′-diphenylmethanecarbodiimide), poly (3,5′-dimethyl-4,4′-biphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m -Phenylenecarbodiimide), poly (3,5'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly (naphthylenecarbodiimide), poly (1,3-diisopropylphenylenecarbodiimide), poly (1-methyl-3,5 Examples include polycarbodiimide compounds such as -diisopropylphenylenecarbodiimide), poly (1,3,5-triethylphenylenecarbodiimide), and poly (triisopropylphenylenecarbodiimide), and these can be used in combination of two or more. Of these, di-2,6-dimethylphenylcarbodiimide, poly (4,4'-diphenylmethanecarbodiimide), poly (phenylenecarbodiimide) and poly (triisopropylphenylenecarbodiimide) are particularly preferably used.

  Moreover, it is preferable to use a carbodiimide compound having a molecular weight of 2000 or more. When the molecular weight is less than 2000, gas or odor may be generated when the residence time is long during melt kneading or molding.

  The blending amount of the (C) carbodiimide compound in the polybutylene terephthalate resin composition is such that when the terminal carboxyl group amount of the (A) polybutylene terephthalate resin is 1 equivalent, the carbodiimide functional group amount is 0.5 to 5 equivalents. An amount is preferred. (C) If the compounding quantity of a carbodiimide compound exists in the said range, the heat shock resistance of a polybutylene terephthalate resin composition can be improved further easily. A more preferable blending amount is such that when the terminal carboxyl group amount of the (A) polybutylene terephthalate resin is 1 equivalent, the amount of the carbodiimide functional group is 0.8 to 4 equivalents, most preferably 1 to 3 equivalents. Is the amount. In the present invention, the adhesion between the fibrous filler of component (B) and (A) polybutylene terephthalate resin is also important. It is considered that the terminal carboxyl group of (A) polybutylene terephthalate resin is related to this adhesion. (C) The carbodiimide functional group of the carbodiimide compound reacts with the terminal carboxyl group of (A) polybutylene terephthalate resin, which may affect the adhesion between (B) component and (A) polybutylene terephthalate resin. Therefore, when the polybutylene terephthalate resin composition of the present invention contains (C) a carbodiimide compound, it is preferable to control the amount of the compound.

[(D) Elastomer]
The polybutylene terephthalate resin composition of the present invention may contain (D) an elastomer. (D) By containing an elastomer, the heat shock resistance of the polybutylene terephthalate resin composition can be further improved. (D) An elastomer can be used individually by 1 type or in combination of 2 or more types.

  Examples of the (D) elastomer include acrylic ester elastomers, diene elastomers, polyorganosiloxane elastomers, and elastomers obtained by copolymerization and / or graft polymerization of two or more of these elastomers.

  Examples of the acrylic ester elastomer include those obtained by polymerizing an acrylic ester such as butyl acrylate and a crosslinkable monomer such as butylene diacrylate. It is preferable to use a small amount of a crosslinkable monomer with respect to the acrylate ester. Examples of the acrylic ester include methyl acrylate, ethyl acrylate, propyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate in addition to butyl acrylate. In addition to butylene diacrylate, crosslinkable monomers include butylene dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, oligoethylene glycol diacrylate, and trimethylolpropane. , Vinyl compounds such as trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, allyl acrylate, allyl methacrylate, diallyl malate, diallyl fumarate, diallyl itanilate, monoallyl malate, monoallyl Examples include allyl compounds such as fumarate and triallyl cyanurate.

  Examples of the diene elastomer include those obtained by polymerizing a butadiene monomer (polybutadiene and butadiene copolymer).

  Examples of the polyorganosiloxane elastomer include those produced by polymerizing an organosiloxane monomer. Examples of the organosiloxane monomer include hexamethyltricyclosiloxane, octamethylcyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane, trimethyltriphenylsiloxane, tetramethylphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane. Etc. are used.

  The blending amount of the (D) elastomer in the polybutylene terephthalate resin composition is preferably 3 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. More preferably, they are 5 to 30 mass parts. (D) If the compounding quantity of an elastomer exists in the said range, the heat shock resistance of a polybutylene terephthalate resin composition can be improved further easily.

[Other ingredients]
The polybutylene terephthalate resin composition of the present invention is generally added to thermoplastic resins and thermosetting resins in order to impart desired properties according to the purpose within a range that does not impair the effects of the present invention. It is possible to blend these substances, for example, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, colorants such as dyes and pigments, lubricants, crystallization accelerators, crystal nucleating agents, etc. It is.

[Preparation method]
The polybutylene terephthalate resin composition of the present invention can be easily prepared using equipment and methods generally used for preparing a resin composition. For example, 1) After mixing each component, kneaded and extruded with a single or twin screw extruder, extruded to prepare pellets, and then molded, 2) once prepared pellets having different compositions, the pellets Any method can be used, such as a method of mixing a predetermined amount of the mixture and subjecting it to molding to obtain a molded product of the desired composition after molding, or 3) a method of directly charging one or more of each component into a molding machine. Further, a method of adding a part of the resin component as a fine powder and mixing it with other components is a preferable method for achieving uniform blending of these components.

<Molded product>
The molded article according to the present invention is formed by molding the polybutylene terephthalate resin composition according to the present invention. A shaping | molding method is not specifically limited, A well-known shaping | molding method is employable. The molded article according to the present invention is preferably an insert molded article formed by insert molding the polybutylene terephthalate resin composition according to the present invention and a metal or an inorganic solid. The metal and the inorganic solid are not particularly limited, and examples of the metal include aluminum, magnesium, stainless steel, and copper, and examples of the inorganic solid include ceramic. Insert molding can be performed by a conventionally known method.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these.
<Material>
Polybutylene terephthalate resin PBT1 (Wintech Polymer Co., Ltd. Juranex (registered trademark), intrinsic viscosity 0.69, terminal carboxyl group amount 24 meq / kg)
Glass fiber Glass fiber 1 (manufactured by Nitto Boseki Co., Ltd., product name: CSF3PE-941, cross-sectional shape: circular, profile ratio 1, cross-sectional diameter 13 μm, length 3.8 mm)
Glass fiber 2 (manufactured by Nitto Boseki Co., Ltd., product name: CSG3PL-830S, cross-sectional shape: oval, profile ratio 2, cross-sectional major axis 14 μm, cross-sectional minor axis 7 μm, length 3.0 mm)
Glass fiber 3 (manufactured by Nitto Boseki Co., Ltd., product name: CSG3PA-830, cross-sectional shape: oval, profile ratio 4, cross-sectional major axis 28 μm, cross-sectional minor axis 7 μm, length 3.0 mm)
Glass fiber 4 (manufactured by Nitto Boseki Co., Ltd., product name: CSH3PA-860, cross-sectional shape: saddle shape, variant ratio 2, cross-sectional major axis 20 μm, cross-sectional minor axis 10 μm, length 3.0 mm)
In addition, in an Example, an oval points out the shape shown in FIG. 1, and a bowl shape points out the shape shown in FIG. 1 and 2, a represents the major axis, b represents the minor axis, and the profile ratio is calculated as a / b.
・ Carbodiimide compound Carbodiimide compound 1 (Rhein Chemie Japan, product name: Stavacsol P400)
Elastomer Elastomer 1 (Rohm and Haas Japan Co., Ltd., product name: Paraloid EXL2314)
・ Antioxidant Antioxidant 1 (manufactured by BASF Japan Ltd., product name: Irganox 1010)

<Examples 1-3, Comparative Examples 1-7>
A polybutylene terephthalate resin composition is prepared by mixing a polybutylene terephthalate resin, glass fibers, a carbodiimide compound, and an antioxidant at a ratio shown in Table 1, and melt-kneading the mixture at 260 ° C. using a 30 mmφ extruder. A pellet consisting of Next, various test pieces were prepared by injection molding, and the following physical properties were evaluated.

[Heat shock resistance]
Using the above pellets, the resin temperature was 260 ° C., the mold temperature was 70 ° C., the injection time was 25 seconds, the cooling time was 10 seconds, and the test piece molding die (length 22 mm, width 22 mm, height 28 mm inside the prism 14 mm, a width of 14 mm, and a mold that inserts an iron core having a height of 24 mm, were subjected to insert injection molding so that the minimum thickness of a part of the resin portion was 1 mm, to produce an insert molded product. The obtained insert molded product was subjected to a heat shock resistance test using a thermal shock tester, which was cooled at −40 ° C. for 1 hour 30 minutes and then heated at 140 ° C. for 1 hour 30 minutes as one cycle. The heat shock resistance was evaluated by measuring the number of cycles until cracks occurred in the molded product. The results are shown in Table 1.

[Melt viscosity]
After the pellets were dried at 140 ° C. for 3 hours, melt viscosity was measured at a furnace temperature of 260 ° C., capillary φ1 mm × 20 mmL, shear rate of 1000 sec ⁻¹ using Capillograph 1B (manufactured by Toyo Seiki Seisakusho) in accordance with ISO11443. It was measured. The results are shown in Table 1.

[Tensile strength (TS) and tensile breaking strain]
After drying the above pellets at 140 ° C. for 3 hours, an ISO 3167 tensile test piece was injection molded at a resin temperature of 260 ° C., a mold temperature of 80 ° C., an injection time of 15 seconds, and a cooling time of 15 seconds, in accordance with ISO 527-1,2. The tensile strength and tensile breaking strain were measured. The results are shown in Table 1.

[Charpy impact strength]
The pellets were injection molded at a molding temperature of 260 ° C. and a mold temperature of 80 ° C. to produce Charpy impact test pieces, and Charpy impact strength was measured at 23 ° C. in accordance with ISO 179 / 1eA. The results are shown in Table 1.

[Pressure Cooker Test (PCT)]
The test piece used for the measurement of tensile strength was treated with a pressure cooker tester at 121 ° C. and 100% RH for 96 hours, the tensile strength after treatment was measured, and the retention before and after the treatment was obtained. . The results are shown in Table 1.

[Flatness]
Using the pellets, five 120 mm × 120 mm × 2 mm flat resin molded products were produced by injection molding under the conditions of a cylinder temperature of 260 ° C., a mold temperature of 80 ° C., and a holding pressure of 70 MPa. The first flat plate-shaped resin molded product was placed on a horizontal plane, and the above-mentioned flat plate-shaped resin molded product was used at 9 locations using a CNC image measuring machine (model: QVBHU404-PRO1F) manufactured by Mitutoyo Corporation. The height from the horizontal plane was measured, and the average height was calculated from the obtained measurement values. The position where the height is measured is that when a square having a side of 114 mm is placed on the main plane of the flat resin molded product so that the distance from each side of the main plane is 3 mm, It is the position corresponding to the vertex, the midpoint of each side of this square, and the center of this square. The height from the horizontal plane was the same as the average height, and a plane parallel to the horizontal plane was used as a reference plane. The maximum height and the minimum height from the reference plane were selected from the heights measured at the nine locations, and the difference between them was calculated. Similarly, for the other four flat resin molded products, the above difference was calculated, and the obtained five values were averaged to obtain a flatness value. The results are shown in Table 1.

As can be seen from Table 1, the polybutylene terephthalate resin compositions of Comparative Examples 1 to 3 containing glass fiber 1 having a circular cross-sectional shape were excellent in heat shock resistance and tensile strength. It was inferior to. The polybutylene terephthalate resin compositions of Comparative Examples 4 to 6 containing glass fibers 3 having an oval cross-section having an odd-shaped ratio of 4 were excellent in tensile strength and flatness, but in heat shock resistance. It was inferior. The polybutylene terephthalate resin composition of Comparative Example 7 containing glass fibers 4 having a bowl-shaped cross-section was excellent in heat shock resistance, but was inferior in tensile strength and flatness.
On the other hand, the polybutylene terephthalate resin compositions of Examples 1 to 6 containing glass fibers 2 having an elliptical shape with a cross-sectional ratio of 2 are any of heat shock resistance, tensile strength, and flatness. Was also excellent. As described above, the polybutylene terephthalate resin composition according to the present invention is excellent in balance among heat shock resistance, mechanical strength, and dimensional stability.

In addition, as shown in FIG. 3, when a polybutylene terephthalate resin composition containing glass fiber 1 having a circular cross-sectional shape or glass fiber 3 having a cross-sectional shape having an elliptical shape with an odd-shaped ratio of 4 is used, the amount of glass fiber added With this increase, the heat shock life was shortened and the heat shock resistance tended to be inferior.
On the other hand, when the polybutylene terephthalate resin composition containing the glass fiber 2 having an elliptical shape with a profile ratio of 2 is used, even if the glass fiber addition amount is increased, the heat shock life is not substantially changed, Excellent heat shock resistance. Thus, the heat shock resistance of the polybutylene terephthalate resin composition according to the present invention is stable regardless of the blending amount of the fibrous filler having a cross-section of (B) an irregularity ratio of 1.5 to 3.5. It is excellent. Therefore, in the polybutylene terephthalate resin composition according to the present invention, in order to obtain a desired mechanical strength, the blending amount of the fibrous filler (B) having a cross-section with an irregularity ratio of 1.5 to 3.5 is increased or decreased. However, excellent heat shock resistance can be stably obtained.

  In addition, the polybutylene terephthalate resin compositions of Examples 2 to 4 have a carbodiimide functional group amount of 1 equivalent, 2 equivalents, and 4 equivalents, respectively, assuming that the terminal carboxyl group amount of the (A) polybutylene terephthalate resin is 1 equivalent. The amount of (C) carbodiimide compound is contained. In Example 3, particularly excellent results were found in terms of the balance between the initial mechanical strength, heat shock resistance and hydrolysis resistance.

Claims (7)

(A) a polybutylene terephthalate resin, and (B) a fibrous filler having a cross section with a profile ratio of 1.9 to 2.5,
(B) is at least one cross-sectional shape of the components is selected oval, elliptical and oval or al,
(B) The compounding quantity of a component is a polybutylene terephthalate resin composition which is 20 to 150 mass parts with respect to 100 mass parts of (A) polybutylene terephthalate resin.   2. The polybutylene terephthalate resin composition according to claim 1, wherein the blending amount of the component (B) is 100.6 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the (A) polybutylene terephthalate resin.   (B) Component is glass fiber, The polybutylene terephthalate resin composition of Claim 1 or 2.   Furthermore, the polybutylene terephthalate resin composition in any one of Claim 1 to 3 which contains the (C) carbodiimide compound.   The polybutylene terephthalate resin composition according to any one of claims 1 to 4, further comprising (D) an elastomer.   A molded article formed by molding the polybutylene terephthalate resin composition according to any one of claims 1 to 5.   The molded article according to claim 6, which is an insert molded article obtained by insert molding the polybutylene terephthalate resin composition and a metal or an inorganic solid.

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