JP5426867B2 - Polybutylene terephthalate resin molded product with weld - Google Patents

Description

  The present invention relates to an injection-molded article having high weld strength, produced using a filler-reinforced polybutylene terephthalate resin composition having excellent mechanical strength, slidability, hydrolysis resistance and molding fluidity.

Polybutylene terephthalate resin (hereinafter sometimes abbreviated as PBT resin) has excellent mechanical and electrical properties, as well as chemical resistance and heat resistance. It is widely used as a material for manufacturing various parts for vehicles such as railway vehicles, various electrical / electronic equipment parts, and general industrial products. In particular, a so-called fiber reinforced PBT resin composition in which a fibrous reinforcing material is blended with a PBT resin has greatly improved mechanical properties, and therefore has an expanded range of use.

However, an injection molded product made of a fiber reinforced PBT resin composition blended with a general fiber reinforcing material often has a low weld strength, which often causes cracks in the molded product. Since the strength of the weld portion is affected by the adhesion of the weld portion and the orientation of the reinforcing fibers, a sufficient effect is often not obtained simply by increasing the amount of the fiber reinforcing material to be blended.

As a method for improving the adhesion of the weld part, it is conceivable to improve the fluidity by lowering the molecular weight of the PBT resin, but this method is not a preferable method. This is because, in this method, there is a problem that the adhesion of the weld portion may be hindered by the decomposition gas generated at the time of molding, and the strength may decrease during use of the molded product due to degradation due to hydrolysis. Because.

In particular, molded products that have become smaller and thinner in recent years are required to use a resin composition that gives higher weld strength, and there are many cases that cannot be solved by conventional formulations. .

In Patent Document 1, when the glass fiber having a flat non-circular cross-section is compared with the glass fiber having a normal circular cross-section, the strength of the thermoplastic resin composition is further improved, especially when the fiber content is large. Describes that the reinforcing effect is large.

Patent Document 2 describes that when a glass fiber having a flat cross section is contained so that the average length in a molded product is 1 mm or more, a molded product having excellent strength is obtained.
Patent Document 3 describes that a glass fiber having a flat cross section is blended with a resin composition composed of a modified PBT resin containing an isophthalic acid unit and a polycarbonate resin.
However, none of the documents describes the strength of the weld part of a molded product using these resin compositions.

Japanese Patent Publication No. 2-60494 JP 2008-95066 A JP 2008-120925 A

The present invention is a molded article comprising a fibrous reinforcing material-containing polybutylene terephthalate resin composition, which has not only high weld strength but also excellent mechanical strength and hydrolysis resistance, and further downsizing and thinning (weight reduction). The object of the present invention is to provide a molded product that can exhibit excellent strength.

As a result of examining the relationship between the physical properties of polybutylene terephthalate resin and the strength of the weld part of an injection-molded product made of a resin composition containing a flat fibrous reinforcing material, particularly the thin weld part. The present inventors have found that a resin composition using a polybutylene terephthalate resin having a specific intrinsic viscosity gives an injection-molded product having a high weld strength.

That is, the gist of the present invention is a polybutylene terephthalate resin having an intrinsic viscosity of 0.60 to 0.78 dL / g measured at 30 ° C. in an equal weight mixed solvent of phenol and 1,1,2,2-tetrachloroethane. (A) Fibrous reinforcing material (B) 65 to 150 parts by weight with a flatness ratio of 2.5 to 10 which is the ratio of the major axis to the minor axis of the cross section perpendicular to the length direction of the fiber with respect to 100 parts by weight, And 0 to 3 parts by weight of the epoxy compound (C). The present invention resides in an injection-molded article having a weld part made of a resin composition.

The injection-molded article according to the present invention is particularly suitable for automotive interior / exterior parts and mechanism parts that are required to have high strength, rigidity, slidability, and hydrolysis resistance and have a thin weld portion and a complicated structure. It can be used and its industrial utility value is extremely high.

Hereinafter, the present invention will be described in detail.
The polybutylene terephthalate resin (A) constituting the resin composition used in the molded article of the present invention is a thermoplastic resin whose main structural unit is butylene terephthalate (—OOC—C ₆ H ₄ —COO—C ₄ H ₈ —). It is. As is well known, PBT resins are industrially produced on a large scale by polycondensation of terephthalic acid or an ester-forming derivative thereof and 1,4-butanediol.

In the production of the PBT resin, it is known that a small amount of other carboxylic acid or alcohol can be used in combination with the above raw materials. In the present invention, such a PBT resin can also be used. Examples of such copolymer components include phthalic acid, metaphthalic acid, cyclohexanedicarboxylic acid, adipic acid, ethylene glycol, propylene glycol, diethylene glycol, cyclohexanediol, and other dicarboxylic acids and diols; glycolic acid, m-hydroxybenzoic acid, p- Hydroxycarboxylic acids such as hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, and p-β-hydroxyethoxybenzoic acid; alkoxycarboxylic acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid And monofunctional compounds such as benzoylbenzoic acid; tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol Such polyfunctional compound having three or more functional, such as fine pentaerythritol.

If the proportion of terephthalic acid units and the proportion of 1,4-butanediol units in the PBT resin are low, the crystallinity of the PBT resin is lowered, and the strength and moldability are lowered. In the present invention, the units of butylene terephthalate (—OOC—C ₆ H ₄ —COO—C ₄ H ₈ —) calculated from the terephthalic acid component or 1,4-butanediol component are at least 80% by weight of the entire PBT resin. %, Usually 90% by weight or more. Preferably, the unit occupies 95% by weight or more of the whole PBT resin. In addition to the above, it is most preferable to use a unit in which this unit calculated from any one occupies 98% by weight or more.

The production of the PBT resin may be performed according to a conventional method. As the catalyst, a conventional catalyst such as a titanium compound, a periodic table group 1 metal compound, a group 2 metal compound, or a tin compound may be used. In addition, when using a titanium compound as a catalyst, it uses so that the catalyst which remains in the resin to produce | generate may be 10-80 ppm in conversion of a titanium atom. Even if the residual amount is larger or smaller than this, the physical properties of the resin composition tend to be lowered. The residual amount in terms of titanium atoms is most preferably 20 to 60 ppm, particularly 30 to 50 ppm.

When a metal compound belonging to Group 1 or Group 2 of the periodic table is used as the catalyst, the catalyst remaining in the produced resin is used so as to be 1 to 50 ppm in terms of metal atoms. If the amount is too large, the hydrolysis resistance of the resin composition may decrease. On the other hand, if the amount is too small, the surface appearance of a molded product obtained from the resin composition may be deteriorated. The residual amount in terms of metal atoms is preferably 5 to 30 ppm, particularly 5 to 20 ppm.

Moreover, when using a tin compound, it uses so that a residual amount may be 200 ppm or less in conversion of a tin atom. If the remaining amount is large, the color tone of the resin deteriorates. The residual amount in terms of tin atoms is preferably 100 ppm or less, particularly preferably 10 ppm or less. The amount of the remaining metal is measured by an atomic emission method after collecting the metal in the resin by a wet ashing method or the like, but can also be measured by atomic absorption, Inductively Coupled Plasma (ICP) or the like.

In producing the PBT resin, the terminal carboxyl group concentration should be 10 to 80 eq / ton. If the terminal carboxyl group concentration is too high, the thermal stability and hydrolysis resistance of the resin composition may be lowered. On the other hand, if it is too low, the sliding characteristics and wear resistance may be reduced. The terminal carboxyl group concentration is preferably 10 to 30 eq / g, particularly preferably 10 to 25 eq / g. The terminal carboxyl group concentration can be measured by a titration method by dissolving 0.5 g of PBT resin in 25 mL of benzyl alcohol and using a 0.01 mol / L benzyl alcohol solution of sodium hydroxide.

In the present invention, among the PBT resins described above, the intrinsic viscosity measured at 30 ° C. in a mixed solvent in which the weight ratio of phenol to 1,1,2,2-tetrachloroethane is 1: 1 is 0.60 to 0.00. The thing of the range of 78 dL / g is used. If a material having an intrinsic viscosity of less than 0.60 dL / g is used, a resin composition that gives sufficient mechanical strength to the molded product cannot be obtained because the molecular weight of the PBT resin is small. Further, since decomposition gas is easily generated during molding, the weld portion is not sufficiently adhered, and the weld strength is likely to be lowered.

On the other hand, if the intrinsic viscosity exceeds 0.78 dL / g, the melt viscosity of the PBT resin increases, so that the fibrous reinforcing material is excessive when kneading the resin composition or manufacturing a molded product from the resin composition. And thus the mechanical strength of the molded product is reduced. Moreover, since the fluidity | liquidity of a resin composition worsens, since a sufficient pressure is not applied to a weld part at the time of shaping | molding, a molded article with a large weld part intensity | strength cannot be obtained.

This phenomenon becomes more remarkable as the weld portion becomes thinner. The range of intrinsic viscosity is more preferably 0.65 to 0.75 dL / g. The PBT resin may be a single type or a mixture of two or more types. For example, two or more types of PBT resins having different intrinsic viscosities may be mixed to obtain a desired intrinsic viscosity.

The fibrous reinforcing material (B) in the present invention improves the mechanical properties (tensile strength, bending strength, impact strength, etc.) of a molded product obtained from the reinforced resin composition according to the present invention, and at the same time welds in the molded product. It functions to improve the strength of the part.

In the present invention, as the fibrous reinforcing material, one having a flatness ratio in the range of 2.5 to 10 which is a ratio of the major axis of the cross section perpendicular to the longitudinal direction of the fiber and the minor axis perpendicular to the longitudinal axis is used. Such a fibrous reinforcing material has a greater effect of improving the mechanical properties of the resin composition than a general reinforcing material having a circular cross-sectional shape. Examples of the fibrous reinforcing material include glass fiber, carbon fiber, basalt fiber, metal fiber, synthetic fiber, silicon carbide fiber, and potassium titanate fiber. Glass fiber, carbon fiber, and basalt fiber are preferred in that the effect of improving mechanical strength is remarkable, and glass fiber is most preferred from the viewpoint of availability.

The shape of the cross section perpendicular to the longitudinal direction of the fibrous reinforcing material B) is usually rectangular, oval close to rectangular, elliptical, longitudinal, as described in JP-A-62-2268612. A saddle type with a narrowed center. Among these, those with a saddle-shaped cross section have a low constriction at the central part and may crack at the central part, and this constricted part may have poor adhesion to the base resin. Is preferably rectangular, oval close to rectangular, or elliptical.

As the fibrous reinforcing material (B), one having an aspect ratio of 2.5 to 10.0 is used. If a fibrous reinforcing material having an aspect ratio of less than 2.5 is used, the resin composition does not give a molded product having a desired high strength. In addition, even if a fibrous reinforcing material with a flatness ratio greater than 10.0 is used, it is crushed by the load applied to the fibrous reinforcing material during the preparation of the resin composition or the manufacturing process of the molded article, and the flatness ratio in the molded article is Get smaller. Moreover, since the fibrous reinforcement with a large flatness is expensive, it is meaningless to use anyway. The flatness of the fibrous reinforcing material is preferably 2.5 to 8.0, particularly 3.0 to 6.0.

The area of the cross section perpendicular to the longitudinal direction of the fibrous reinforcing material (B) is usually in the range of ² × 10 ^{−5 to} 8 × 10 ⁻³ mm ² . Fibrous reinforcements with a smaller cross-sectional area are generally difficult to spin and expensive, and conversely, those with a larger cross-sectional area have a smaller contact area with the resin and a higher rigidity, and can be used as a reinforcing material. The function of is not fully fulfilled. Sectional area of the fibrous reinforcing material is preferably in the range of ^8x10 -5 ^~8x10 -4 mm ^2, particularly ^8x10 -5 ^~5x10 -4 mm ^2.

The longer the fibrous reinforcing material (B), the greater the reinforcing effect, but the longer the fiber, the easier it is to crush when preparing a resin composition by melting and kneading with a resin, and when producing a molded product from the resin composition. Also crush. As the fibrous reinforcing material used for melting and kneading, a chopped strand having a length of about 0.5 to 20.0 mm is usually used, but the length of the fibrous reinforcing material in the resin composition is crushed by melt kneading. Is usually about 0.3 to 1.0 mm.

The length of the fibrous reinforcing material in the molded product is slightly shorter than this and is about 0.2 to 0.9 mm. When producing a molded article having a weld portion according to the present invention, the average length of the fibrous reinforcing material (B) contained in the molded article is 0.3 to 3 so that the fibrous reinforcing material is not broken as much as possible. The thickness is preferably 0.9 mm, particularly 0.4 to 0.9 mm.

The fibrous reinforcing material (B) can be produced, for example, by the method described in Japanese Patent Publication No. 3-59019, Japanese Patent Publication No. 4-13300, Japanese Patent Publication No. 4-32775, and the like. For example, in an orifice plate having a plurality of orifices on the bottom surface, an orifice plate that surrounds a plurality of orifice outlets and has a convex edge extending downward from the bottom surface of the orifice plate, or a nozzle tip having one or more orifice holes It can be manufactured using a modified cross-section glass fiber spinning nozzle tip provided with a plurality of convex edges extending downward from the front end of the outer peripheral portion.

The fibrous reinforcing material (B) may be surface-treated with a silane coupling agent, a lubricant, an antistatic agent, a resin having a film forming ability, or the like. Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like.

The adhesion amount of the silane coupling agent is preferably 0.01% by weight or more of the fibrous reinforcing material. Examples of the lubricant include fatty acid amide compounds and silicone oils. Examples of the antistatic agent include quaternary ammonium salts. Examples of the resin having a film forming ability include epoxy resins and urethane resins. . A heat stabilizer, a flame retardant, etc. can also be mix | blended with resin which has a film formation ability previously.

Content of the fibrous reinforcement (B) in a resin composition is 65-150 weight part with respect to 100 weight part of polybutylene terephthalate resin (A), Preferably it is 80-150 weight part. If the content is less than 65 parts by weight, the strength and weld strength of the molded product are not sufficient, and no significant difference is observed from the case where a conventional fiber reinforcing material having a circular cross section is used. On the other hand, if the content exceeds 150 parts by weight, the resin composition is easily crushed and difficult to be pelletized when melted and kneaded with the resin to prepare the resin composition. Moreover, when manufacturing a molded article from a resin composition, a fibrous reinforcement is crushed easily. The content of the fibrous reinforcing material (B) with respect to 100 parts by weight of the PBT resin is most preferably 90 to 150 parts by weight, particularly 90 to 125 parts by weight.

The epoxy compound (C) functions to improve the moisture and heat resistance characteristics of the resin composition, and to further improve the strength and durability of the weld part of the molded product. Therefore, among the molded products according to the present invention, molded products made of a resin composition containing an epoxy compound are suitable for use in places exposed to wet heat conditions during use, such as automobile parts.

As an epoxy compound (C), what is necessary is just to have one or more epoxy groups in one molecule, and usually a glycidyl compound which is a reaction product of alcohol, phenols or carboxylic acid and epichlorohydrin, A compound obtained by epoxidizing an olefinic double bond may be used.

For example, the following epoxy compounds can be used. Bisphenol A type epoxy compound, bisphenol F type epoxy compound, resorcinol type epoxy compound, novolac type epoxy compound, alicyclic compound type diepoxy compound, glycidyl ethers, glycidyl esters, epoxidized polybutadiene. Examples of the alicyclic compound type epoxy compound include vinylcyclohexene dioxide and dicyclopentadiene oxide.

Specific examples of glycidyl ethers include monoglycidyl ethers such as methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, decyl glycidyl ether, stearyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, and allyl glycidyl ether; Examples include diglycidyl ethers such as pentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, propylene glycol diglycidyl ether, and bisphenol A diglycidyl ether.

Examples of the glycidyl esters include monoglycidyl esters such as glycidyl benzoate and glycidyl sorbate; diglycidyl esters such as adipic acid diglycidyl ester, terephthalic acid diglycidyl ester, and orthophthalic acid diglycidyl ester. .

The epoxy compound (C) may be a copolymer having a glycidyl group-containing compound as one component. For example, a copolymer of glycidyl ester of α, β-unsaturated acid and one or two or more monomers selected from the group consisting of α-olefin, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester It is done.

The epoxy compound (C) is preferably an epoxy compound having an epoxy equivalent of 100 to 500 g / eq and a weight average molecular weight of 2000 or less. When the epoxy equivalent is less than 100 g / eq, since the amount of the epoxy group is too large, the viscosity of the resin composition becomes high, which causes a decrease in the weld adhesion. On the other hand, when the epoxy equivalent exceeds 500 g / eq, the amount of epoxy groups decreases, so that the effect of improving the heat-and-moisture resistance characteristics of the resin composition is not sufficiently exhibited.

When the weight average molecular weight exceeds 2000, the compatibility with the polybutylene terephthalate resin is lowered, and the mechanical strength of the molded product tends to be lowered. The epoxy compound is preferably a bisphenol A type epoxy compound or a novolac type epoxy compound obtained from a reaction of bisphenol A or novolak with epichlorohydrin.

Although content of an epoxy compound (C) is 0-3 weight part with respect to 100 weight part of polybutylene terephthalate resin (A), in order to express a containing effect, it is preferable to contain 0.1 weight part or more. When the content is more than 3 parts by weight, the crosslinking proceeds and the fluidity at the time of molding deteriorates. The epoxy compound (C) is most preferably contained in an amount of 0.2 to 2 parts by weight with respect to 100 parts by weight of the PBT resin.

In addition to the components (A) to (C), the resin composition for producing the molded article according to the present invention may have other thermoplastic properties as long as the properties of the resin composition are not impaired. Resins and conventional resin additives may be included.

Examples of other thermoplastic resins include polyester resins such as polyethylene terephthalate resin (PET resin) and polyethylene naphthalate resin (PEN resin), olefin resins such as polyethylene and polypropylene, polyamides, polystyrene, acrylonitrile-styrene copolymer Styrenic resins such as coalescence resin (AS resin), acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyvinyl chloride, polyvinyl acetate, polycarbonate, polyacetal, polyphenylene ether, polyphenylene sulfide, liquid crystal polymer, etc. It is done. These thermoplastic resins should be up to 50 parts by weight at the most with respect to 100 parts by weight of the polybutylene terephthalate resin (A), and are usually 40 parts by weight, preferably 30 parts by weight or less. .

Examples of resin additives to be included include heat release agents such as fatty acid ester-based, paraffin-based, polyolefin-based, bisamide-based, silicone-based release agents, hindered phenol-based, phosphite-based, sulfur-containing ester compound-based Agents, inorganic fillers such as mica and talc, impact modifiers, flame retardants, flame retardant aids, ultraviolet absorbers, weather resistance imparting agents, slidability imparting agents, colorants such as dyes and pigments, foaming agents, etc. There is.

In order to prepare a resin composition for producing a molded article according to the present invention, a conventional method for preparing a resin composition may be used. Preferably, a method of melting and kneading using an extrusion kneader or the like is used. Specifically, PBT resin (A), fibrous reinforcing material (B), epoxy compound (C), and additive components used as required are blended in predetermined amounts, and ribbon blender, V-type blender, Hensel mixer, drum A method of mixing with a blender such as a blender and melting and kneading with a melting and kneading machine can be mentioned.

When melting and kneading, a method of feeding each component to the melting and kneading machine at once or a method of feeding sequentially may be used. Examples of the melting / kneading machine include various extruders, Brabender plastographs, lab plast mills, kneaders, and Banbury mixers. When melting and kneading, it is preferable to feed those which are easily decomposed or easily broken. Various additive components can also be mixed in advance with PBT resin and other additive components. Since the fibrous reinforcing material is easily crushed during kneading, it is preferably fed halfway. The heating temperature at the time of melting and kneading is determined depending on the type and ratio of the components to be blended, but is preferably in the range of 230 to 290 ° C.

Manufacture of the molded article from a resin composition can be performed by a conventional injection molding method. In the injection molding, it is preferable to adjust the temperature of the resin composition to 240 to 280 ° C and the mold temperature to 60 to 120 ° C, particularly 80 to 120 ° C. In general, from the viewpoint of securing fluidity and crystallinity, a higher mold temperature is preferable. The method of injecting the resin composition into the mold is not particularly limited as long as the weld part is formed in the molded product, and the number of injection ports may be one or more.

The thickness of the molded article according to the present invention is arbitrary, but the effect of improving the strength is more remarkable in a molded article having a thin part, particularly a molded article having a thin weld part. Therefore, the effect is remarkable in a molded product having a thickness of 1.5 mm or less, particularly 1 mm or less, and particularly in a molded product having a weld portion having a thickness of 1.5 mm or less, particularly 1 mm or less.

The use suitable for the molded article according to the present invention is a part having a weld part and requiring high mechanical strength and durability in a moist heat environment. Specifically, it is interior / exterior parts and mechanism parts for automobiles, for example, mechanism / structure parts used for wipers, doors, mirrors, roof rails, windows, seats, lamp systems, steering systems, drive systems, and fenders. , Exterior parts such as doors, trunks, and back doors, and electrical parts such as audio, monitors, and cameras.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to the example described below. In addition, each component used in the example described below is as follows.

Polybutylene terephthalate resin (A):
(A-1) PBT resin # 1: Polybutylene terephthalate having an intrinsic viscosity of 0.70 dL / g (manufactured by Mitsubishi Engineering Plastics Co., Ltd., trade name: NOVADURAN 5007).

(A-2) PBT resin # 2: Polybutylene terephthalate having an intrinsic viscosity of 0.60 dL / g, and was prepared by the following method.

A total of 3,229 parts by weight is supplied to the transesterification reactor at a ratio of 1.8 moles of 1,4-butanediol to 1.0 mole of dimethyl terephthalate, and 3.14 parts by weight of tetrabutyl titanate is added. Then, an ester exchange reaction was performed at a temperature of 210 ° C. and a pressure of 101 kPa for 3 hours to obtain an oligomer. Subsequently, this oligomer was transferred to a polycondensation reaction tank, and a polymer was obtained by performing a polycondensation reaction at 250 ° C. under a pressure of 133 Pa for 2 hours under stirring. The polymer was extruded from the polycondensation reaction tank into a strand shape by nitrogen pressure and cut with a pelletizer to obtain pellet-shaped PBT resin # 2.

(A-3) PBT resin # 3: polybutylene terephthalate having an intrinsic viscosity of 0.85 dL / g (manufactured by Mitsubishi Engineering Plastics, trade name: NOVADURAN 5008).

Fibrous reinforcement (B):
(B-1) Oval-shaped cross-section glass fiber: Flatness ratio 4, {(major axis + minor axis) / 2} = 17.5 μm, fiber length L = 3 mm oval cross-section glass fiber (manufactured by Nittobo Co., Ltd., brand name) : CSG3PA830).

(B-2) Circular cross-section glass fiber: (Nippon Electric Glass Co., Ltd., brand name: ECT03T187).

Epoxy compound (C):
(C-1) N type epoxy: novolak type epoxy compound (manufactured by Toto Kasei Co., Ltd., trade name: Epototo YDCN704).

(C-2) BA type epoxy: bisphenol A type epoxy compound (Asahi Denka Co., Ltd., trade name: Adeka Sizer EP17).

Preparation of resin composition:
Said PBT resin (A), fibrous reinforcement (B), and epoxy compound (C) were mix | blended in the ratio (weight part) described in Table-1-Table-2, and were mixed for 10 minutes with the Henschel mixer. . The obtained mixture was melted and melted by a twin-screw extruder (manufactured by Nippon Steel Works, model: TEX-30C, the barrel is composed of 9 blocks) whose barrel (cylinder) temperature was set to 260 ° C. It knead | mixed and pelletized. At the time of melting and kneading, the fibrous reinforcing material was supplied by a side feed system from the fifth block from the extruder hopper side.

Preparation of test piece Using the obtained pellet as a raw material, using an injection molding machine (manufactured by Sumitomo Heavy Industries, model: SG-75SYCAP-MIII), setting the cylinder temperature to 250 ° C and the mold temperature to 80 ° C. Test specimens for standard tensile strength tests and tensile tests with welds in the center (thickness of 1 mm and 4 mm, see Fig. 1), and notched Charpy impact strength test specimens conform to ISO And molded.

Test piece evaluation method (a) Standard tensile strength (MPa): Measured on test pieces having a thickness of 1 mm and 4 mm in accordance with ISO527.

(B) Weld strength ratio (%): A tensile test piece (thickness 4 mm) having a weld in the center is subjected to a tensile test using an INSTRON universal testing machine 5569, and the obtained fracture strength is compared with the reference tensile strength. Expressed in

(C) Thin weld strength ratio (%): A tensile test piece with a thickness of 1 mm having a weld in the center is subjected to a tensile test using a universal testing machine 5544 manufactured by INSTRON Co., Ltd., and the obtained breaking strength is compared with the reference tensile strength. Expressed in

(E) Notched Charpy impact strength (KJ / m ² ): Measured according to ISO 179-1179-2.

(D) Thin-walled weld strength ratio after wet heat treatment (%): Using a pressure cooker tester PC-422R5E manufactured by Hirayama Seisakusho, 85 ° C, 95% RH After carrying out the treatment for 2000 hours under the conditions, a tensile test was conducted with a universal testing machine 5544 manufactured by INSTRON Co., Ltd., and the obtained breaking strength was expressed as a ratio to the reference tensile strength.

(F) Fracture load (kN) of molded product having a weld part: A test piece was prepared and evaluated by the following method.

Preparation of test piece:
Using an injection molding machine (manufactured by Sumitomo Heavy Industries, model: SG-75SYCAP-MIII), setting the cylinder temperature to 250 ° C. and the mold temperature to 80 ° C., a model molded product having a weld part (see FIG. 2) ). The model molded article has a cylindrical shape with a diameter of 40 mm, a height of 20 mm, and a thickness of 1 mm, and has a cross-shaped column having a width of 3 mm at the top, and a gate having a diameter of 1 mm at the center of the cross-shaped column. Since the molten resin injected from the gate at the time of molding flows into the cylindrical portion through the cross-shaped column, a weld is generated in the cylindrical portion due to the difference in the flow path.

Evaluation test Breaking load when a steel (S45C) jig with a taper of 5 ° is inserted into this cylindrical molded product using an A & D universal testing machine RTC-1310A ( KN) was measured.

(G) Weight average fiber length (mm) in the molded product:
About 5 g of a sample was cut out from the above cylindrical model molded article and placed in an electric furnace at a temperature of 600 ° C. for 2 hours to be ashed. The remaining fibrous reinforcing material was dispersed in an aqueous surfactant solution (neutral) with care not to break it, and the dispersed aqueous solution was transferred onto a slide glass with a pipette and photographed with a microscope. With respect to this photographic image, 1000 to 2000 reinforcing fibers were measured by image analysis software, and the weight average fiber length was calculated.

Examples 1-7 and Comparative Examples 1-8
Each evaluation mentioned above was performed about the resin composition of the mixture ratio of Table 1 and 2. The results are shown in Tables 1 and 2. However, Example 5 is a reference example.

Table 1 and Table 2 show the following.

(1) About what made PBT resin contain the glass fiber of the flat rate prescribed | regulated by this invention;
When the intrinsic viscosity of the PBT resin is 0.70 dL / g (Example 1 to Example 5), it becomes a reference as compared with the case where the intrinsic viscosity is 0.85 dL / g (Comparative Example 1 to Comparative Example 5). It can be seen that, in addition to the improvement in tensile strength, the effect of improving the weld strength ratio is large, and the effect of improving the weld strength ratio is particularly remarkable in the case of a thin wall.

(2) About intrinsic viscosity of PBT resin;
When the intrinsic viscosity is 0.70 dL / g (Example 1), compared with the case where the intrinsic viscosity is 0.60 dL / g (Example 6) and the case where the intrinsic viscosity is 0.775 (Example 7). It can be seen that the standard tensile strength, thin-walled weld strength ratio, weld strength ratio after wet heat treatment, etc. are slightly higher and more preferable.

(3) Glass fiber shape;
When the glass fiber having the flatness specified in the present invention is contained in the PBT resin (Example 1), the tensile strength serving as a reference is higher than that when the glass fiber having a circular cross section is contained (Comparative Example 6). It can be seen that the improvement is noticeable, and that the absolute value of the weld strength increases with the improvement of the weld strength ratio.

(4) Even when the glass fiber having the flatness specified in the present invention is contained in the PBT resin, when the content is as small as 50 parts by weight, the intrinsic viscosity of the PBT resin is 0.70 dL / g Even when (Comparative Example 7) is compared with the case of 0.85 dL / g (Comparative Example 8), it is understood that there is not much difference in the weld strength ratio and the effect is not seen.

(5) About the amount of fiber blended;
The standard tensile strength is higher when the blending amount is 82 parts by weight (Example 2) than when the blending amount is 67 parts by weight (Example 3), and when the blending amount is 100 parts by weight (Example). It can be seen that 1) is preferable because the reference tensile strength is higher and the absolute value of the weld strength is higher even if the weld strength ratio is not significantly different.

(6) Effect of epoxy compound;
When the flat fiber glass fiber specified in the present invention is contained in the PBT resin and the epoxy compound is further contained (Example 1 and Example 4), compared to the case where the epoxy compound is not contained (Example 5). It can be seen that the weld strength ratio after the wet heat treatment is high, and the durability of the weld strength is excellent and preferable.

It is explanatory drawing of the test piece for weld strength measurement. It is a perspective view explaining the molded article which has a weld part, and its destructive test method.

Claims (8)

100 parts by weight of polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.60 to 0.78 dL / g measured at 30 ° C. in an equal weight mixed solvent of phenol and 1,1,2,2-tetrachloroethane Further, 65 to 150 parts by weight of a fibrous reinforcing material (B) having a flatness ratio of 2.5 to 10 which is a ratio of a major axis and a minor axis of a cross section perpendicular to the fiber length direction, and an epoxy compound (C) 0.2 An injection-molded article having a weld part having a thickness of 1.5 mm or less, comprising a resin composition characterized by containing ˜2 parts by weight. The content of the butylene terephthalate structural unit (—OOC—C ₆ H ₄ —COO—C ₄ H ₈ —) calculated from the terephthalic acid component or the 1,4-butanediol component in the polybutylene terephthalate resin (A) The injection-molded product according to claim 1 , which is 95% by weight or more. The injection molded product according to claim 1 or 2 , wherein the content of the fibrous reinforcing material is 90 to 125 parts by weight. The injection molded product according to any one of claims 1 to 3 , wherein the flatness of the fibrous reinforcing material is 3.0 to 6.0. The injection-molded article according to any one of claims 1 to 4 , wherein the fibrous reinforcing material is glass fiber. The injection-molded article according to any one of claims 1 to 5 , wherein the epoxy compound has an epoxy equivalent of 100 to 500 g / eq and a weight average molecular weight of 2000 or less. The injection-molded product according to any one of claims 1 to 6 , wherein the injection-molded product is used for an interior / exterior part or a mechanism part for automobiles. Intrinsic viscosity measured at 30 ° C. in an equal weight mixed solvent of phenol and 1,1,2,2-tetrachloroethane is 0.6 to 0.78 dL / g, and a terephthalic acid component or 1,4-butane In 100 parts by weight of the polybutylene terephthalate resin (A) in which the content of the butylene terephthalate structural unit (—OOC—C ₆ H ₄ —COO—C ₄ H ₈ —) calculated from the diol component is 95% by weight or more. On the other hand, 90 to 125 parts by weight of glass fiber (B) having a flatness ratio of 3.0 to 6.0, which is a ratio of a major axis to a minor axis of a cross section perpendicular to the fiber length direction, and an epoxy equivalent of 100 to 500 g / eq, a resin composition characterized by containing 0.2 to 2 parts by weight of an epoxy compound (C) having a weight average molecular weight of 2000 or less, a weld part having a thickness of 1.5 mm or less is formed on a molded product. Ruyo Method for manufacturing an injection-molded article having a weld portion, wherein the injection into the mold.

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