JP7183536B2 - Polybutylene terephthalate resin composition for molded article for welding polyester elastomer and composite molded article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polybutylene terephthalate resin composition having improved adhesion to polyester elastomers.

Polybutylene terephthalate resin has excellent mechanical properties, electrical properties, and other physical and chemical properties, as well as good processability. Therefore, it is used as an engineering plastic in a wide range of applications such as automobiles and electrical and electronic parts. ing.
However, although the molding efficiency of the injection-molded article is good, there are restrictions on the shape due to its flow characteristics and mold structure, and it has been difficult to mold, for example, a hollow molded article. For this reason, conventionally, when joining parts having complicated product shapes, joining with an adhesive or mechanical joining with bolts or the like has been performed. However, adhesives pose problems of adhesive strength, and mechanical joining using bolts or the like poses problems of cost, time and effort for fastening, and increased weight.

Bonding methods such as hot plate welding, vibration welding, laser welding, and ultrasonic welding can be performed in a short period of time, and there is no need to use adhesives or metal parts. Since problems such as environmental pollution can be reduced, joining of parts by these methods is increasing (Patent Documents 1, 2, 3, and 4).

Patent Document 1 discloses that adding an elastomer and glass fiber to a polybutylene terephthalate resin improves the vibration weldability without significantly deteriorating the mechanical properties. However, these methods require the use of a special machine for vibration welding, and burrs generated during vibration welding may require a post-treatment process for the burrs. Patent Document 2 shows that adding an elastomer and glass fiber to a polybutylene terephthalate resin results in excellent durability and hydrolysis resistance in a thermal cycle environment. However, the disclosed composition is a secondary material for insert molding, and although the hydrolysis resistance is improved, the adhesion resistance is not sufficient, and the insert bondability is also insufficient. In Patent Document 3, it is found that by limiting the number of terminal carboxyl groups and adding carbodiimide, hydrolysis resistance is improved without significantly deteriorating mechanical properties. However, although this composition is excellent as a material for heat welding, it requires the use of a special machine for heat welding at the time of joining, as in Patent Document 1, and burrs are generated at the heat-welded portion as in vibration welding. However, a post-treatment step for burrs may occur. In Patent Document 4, there is a correlation between the molecular weight of polybutylene terephthalate resin and the vibration welding strength. does not impair. However, as in Patent Document 1, this patent document also requires the use of a special machine for vibration welding at the time of joining, which may cause burrs at the welded portion and may require a post-treatment process for burrs.

By the way, if joining can be performed by insert molding, a composite molded body can be easily molded without special welding equipment. Furthermore, in mechanical joining such as vibration welding, there is also a problem that molding conditions vary greatly. Moreover, Patent Documents 1 to 4 do not include any technical idea of joining a polyester elastomer to a polybutylene terephthalate resin-based molding by insert molding.

JP 2006-176691 A WO 2009/150831 Pamphlet WO 2010/122915 pamphlet International Publication No. 2013/047708 pamphlet

The present invention aims to solve the above problems, and can be joined (welded) by insert molding without the need for special welding equipment, and has a practical joint strength even at stress-generating sites. To provide a polybutylene terephthalate resin composition having In particular, there is a demand from the market for a composite molded product that combines (welds) a polyester elastomer to a polybutylene terephthalate resin-based molded product by insert molding and has the excellent properties of both polybutylene terephthalate resin and polyester elastomer. A resin composition for a polybutylene terephthalate resin-based molded product, which is necessary for this composite molded product, is desired. When the present inventors investigated, it was difficult to join (weld) a polyester elastomer or other resin to a polybutylene terephthalate resin molded product by insert molding, but it was difficult to join (weld) in a practical manner. It was also found that the shape of the molded body is restricted and it cannot be used for parts where stress is applied to the joint. Accordingly, an object of the present invention is to provide a polybutylene terephthalate resin composition for a molded body for welding a polyester elastomer, which can be joined by insert molding, and has practical joining strength even at stress-generating sites. and Furthermore, a polybutylene terephthalate resin composition for a molded article that can give a molded article with a good surface appearance even when the mechanical properties are improved by reinforcing the glass fiber. The task is to provide

The inventors of the present invention have completed the present invention as a result of earnestly studying the configuration and characteristics of the polybutylene terephthalate resin composition in order to solve the above problems.

That is, the present invention has the following configurations.
[1] Polybutylene terephthalate resin (A) 20 to 95% by mass, polyester elastomer (B) 4 to 42% by mass, copolymer polyester resin (C) 0 to 50% by mass, and glass fiber having a non-circular fiber cross section (D) A polybutylene terephthalate resin composition containing 1 to 60% by mass, which is for a molded article to which a polyester elastomer is to be welded.
[2] The glass fiber (D) is a flat cross-section glass fiber or a cocoon-shaped cross-section glass fiber having an average ratio of the major axis to the minor axis (major axis/minor axis) of the fiber cross section of 1.5 to 8. The polybutylene terephthalate resin composition according to [1].
[3] The above-mentioned copolymer polyester resin (C) is a polyester resin obtained by copolymerizing ethylene terephthalate units or butylene terephthalate units with at least one of alkyl side chain-containing glycols and isophthalic acid. The polybutylene terephthalate resin composition of
[4] A composite molded article obtained by welding a molded article made of the polybutylene terephthalate resin composition according to any one of [1] to [3] and a polyester elastomer.
[5] Manufacture of a composite molded body by disposing a molded body made of the polybutylene terephthalate resin composition according to any one of [1] to [3] as an insert material in a mold and welding a polyester elastomer by injection molding. Method.

According to the present invention, even polybutylene terephthalate resin can be joined with a polyester elastomer by insert molding by adding a polyester elastomer. Further, when glass fibers are added, the use of glass fibers having a flat or cocoon-shaped fiber cross section can improve the fluidity and improve the appearance of the molded product. The composite molded article in which the molded article made of the polybutylene terephthalate resin composition of the present invention and the polyester elastomer are welded is an insert composite molded article that can be obtained by a simple method called insert molding without requiring special equipment. be. In addition, at the joint of the composite molded article, the molded article made of the polybutylene terephthalate resin composition and the polyester elastomer are directly joined (welded) without using an adhesive or a bolt. It has sufficient bonding strength for practical use.

The present invention will be specifically described below.
[Polybutylene terephthalate resin (A)]
Polybutylene terephthalate resin is a general polycondensation reaction of a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof as a main component and a diol containing 1,4-butanediol or an ester-forming derivative thereof as a main component. It is a polymer that can be obtained by a conventional polymerization method. The polybutylene terephthalate resin preferably contains 80 mol% or more repeating units of butylene terephthalate, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol%. is particularly preferred.

The polybutylene terephthalate resin can contain other polymerization components within a range that does not impair its properties, for example, about 20% by mass or less. Examples of polybutylene terephthalate resins containing other polymeric components include polybutylene (terephthalate/isophthalate), polybutylene (terephthalate/adipate), polybutylene (terephthalate/sebacate), polybutylene (terephthalate/decanedicarboxylate), polybutylene (terephthalate / naphthalate), poly(butylene/ethylene) terephthalate, and the like. These components may be used alone or in combination of two or more.

The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited, but is preferably 0.5 to 1.6 dl/g, more preferably 0.7 to 1.3 dl/g. and more preferably 0.8 to 1.1 dl/g. The polybutylene terephthalate resin composition produced by the present invention has good mechanical properties and chemical properties because the polybutylene terephthalate resin has an intrinsic viscosity (IV) of 0.5 to 1.6 dl/g. .

The amount of terminal carboxyl groups in the polybutylene terephthalate resin is not particularly limited because it does not affect bonding properties. However, since terminal carboxyl groups play a catalytic role in the hydrolysis reaction of polymers, hydrolysis is accelerated as the amount of terminal carboxyl groups increases. Therefore, the concentration of terminal carboxyl groups is preferably low. The terminal carboxyl group concentration (acid value) of the polybutylene terephthalate resin is preferably 40 eq/ton or less, more preferably 30 eq/ton or less, and still more preferably 25 eq/ton or less.

The concentration (unit: eq/ton) of the terminal carboxyl group of the polybutylene terephthalate resin can be obtained, for example, by dissolving a predetermined amount of the polybutylene terephthalate resin in benzyl alcohol and using a 0.01 mol/1 benzyl alcohol solution of sodium hydroxide. It can be measured by titrating with A phenolphthalein solution, for example, may be used as the indicator.

The content of the polybutylene terephthalate resin (A) is 20 to 95% by mass, preferably 25 to 95% by mass, more preferably 50 to 80% by mass in the polybutylene terephthalate resin composition. By blending the polybutylene terephthalate resin (A) within this range, it becomes possible to obtain a polybutylene terephthalate resin composition capable of bonding to a polyester elastomer having practical bonding strength.

[Polyester elastomer (B)]
The polyester elastomer (B) used in the present invention includes a hard segment composed of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and/or alicyclic glycol, an aliphatic polyether, an aliphatic polyester and an aliphatic It is preferably a polyester elastomer to which at least one soft segment selected from group polycarbonates is bonded.

In the polyester elastomer (B) used in the present invention, the aromatic dicarboxylic acid constituting the polyester of the hard segment is widely used and is not particularly limited, but specific examples include terephthalic acid and isophthalic acid. acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, diphenyl-p,p-dicarboxylic acid, and these functional derivatives of Preferred are terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and diphenyl-p,p-dicarboxylic acid, which tend to have a high crystallization rate and good moldability. Particularly preferred are terephthalic acid and terephthalic acid dimethyl ester, isophthalic acid and isophthalic acid dimethyl ester, 2,6-naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid dimethyl ester. Furthermore, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, glutaric acid and dimer acid and functional derivatives thereof, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid and cyclohexanedicarboxylic acid, and Less than 50 mol % of functional derivatives thereof can also be used. The content of components other than the aromatic dicarboxylic acid is preferably less than 50 mol%, more preferably less than 40 mol%, and still more preferably less than 30 mol%. Moldability and heat resistance tend to decrease.

In addition, in the polyester elastomer (B) used in the present invention, general aliphatic or alicyclic glycols are widely used as the aliphatic or alicyclic glycol constituting the hard segment polyester, and are not particularly limited, but are mainly Alkylene glycols having 2 to 8 carbon atoms are desirable. Preferred are ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol and 1,4-cyclohexanedimethanol, and particularly preferred are ethylene glycol and 1,4-butanediol. is either

As a component constituting the polyester of the hard segment, those composed of ethylene terephthalate units (units consisting of terephthalic acid and ethylene glycol) or butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) have physical properties, It is preferable in terms of moldability and cost performance.

Further, when an aromatic polyester suitable as a polyester constituting the hard segment in the polyester elastomer (B) used in the present invention is produced in advance and then copolymerized with the soft segment component, the aromatic polyester is a normal polyester can be easily obtained according to the manufacturing method of Moreover, such polyester preferably has a number average molecular weight of 10,000 to 40,000.

The soft segment of the polyester elastomer (B) used in the present invention is at least one selected from aliphatic polyethers, aliphatic polyesters and aliphatic polycarbonates. Aliphatic polyethers include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, polyoxytrimethylene glycol, copolymers of ethylene oxide and propylene oxide, and ethylene oxide of polyoxyethylene glycol. adducts, copolymers of ethylene oxide and tetrahydrofuran, and the like.
Aliphatic polyesters include poly(ε-caprolactone), polyenantholactone, polycaprylolactone, and polybutylene adipate.

Moreover, the aliphatic polycarbonate is preferably composed mainly of aliphatic diol residues having 2 to 12 carbon atoms. Examples of these aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2, 2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8- octanediol and the like. In particular, aliphatic diols having 5 to 12 carbon atoms are preferred from the viewpoint of the flexibility and low-temperature properties of the resulting polyester elastomer (B). These components may be used alone, or two or more of them may be used in combination according to the cases described below.

In the present invention, the aliphatic polycarbonate diol having good low-temperature properties, which constitutes the soft segment of the polyester elastomer usable in the present invention, preferably has a low melting point (for example, 70° C. or lower) and a low glass transition temperature. Aliphatic polycarbonate diols composed of 1,6-hexanediol, which is generally used to form the soft segment of polyester elastomers, have a low glass transition temperature of around -60°C and a melting point of around 50°C. will be good. In addition, an aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1,5-pentanediol with the above aliphatic polycarbonate diol has a glass transition point higher than that of the original aliphatic polycarbonate diol. is slightly higher, but the melting point is lowered or becomes amorphous. For example, an aliphatic polycarbonate diol composed of 1,9-nonanediol and 2-methyl-1,8-octanediol has a melting point of about 30° C. and a glass transition temperature of about −70° C., which are sufficiently low. corresponds to a good aliphatic polycarbonate diol.

The polyester elastomer (B) used in the present invention should be a copolymer containing terephthalic acid, 1,4-butanediol, and polyoxytetramethylene glycol as main components for reasons of economy, heat resistance, and cold resistance. is preferred. Among the dicarboxylic acid components constituting the polyester elastomer (B), terephthalic acid is preferably 40 mol% or more, more preferably 70 mol% or more, further preferably 80 mol% or more, and 90 mol%. % or more is particularly preferable. In the glycol component constituting the polyester elastomer (B), the total amount of 1,4-butanediol and polyoxytetramethylene glycol is preferably 40 mol% or more, more preferably 70 mol% or more, and 80 mol. % or more, and particularly preferably 90 mol % or more.

The polyoxytetramethylene glycol preferably has a number average molecular weight of 500 to 4,000. If the number average molecular weight is less than 500, it may be difficult to develop elastomeric properties. On the other hand, if the number average molecular weight exceeds 4,000, the compatibility with the polyester portion constituting the hard segment of the polyester elastomer (B) may be lowered, making block-like copolymerization difficult. The number average molecular weight of polyoxytetramethylene glycol is more preferably 800 or more and 3000 or less, even more preferably 1000 or more and 2500 or less.

Regarding the copolymerization amount of the hard segment and the soft segment of the polyester elastomer (B) used in the present invention, the mass ratio of hard segment/soft segment is preferably 85/15 to 35/65, more preferably 75. /25 to 50/50.

The hardness (surface hardness) of the polyester elastomer (B) used in the present invention is not particularly limited, but a wide range of polyester elastomers can be used, for example, from a low hardness of about 25 Shore A hardness to a high hardness of about 75 Shore D hardness. It is possible and preferably has a Shore D hardness of 25 to 65, more preferably 25 to 40.

The reduced viscosity of the polyester elastomer (B) used in the present invention is preferably 0.5 dl/g or more and 3.5 dl/g or less when measured by the method described below. If it is less than 0.5 dl/g, the durability as a resin is low, and if it exceeds 3.5 dl/g, processability such as injection molding may become insufficient. The reduced viscosity of the polyester elastomer (B) is more preferably 1.0 dl/g or more and 3.0 dl/g or less, and further preferably 1.5 dl/g or more and 2.8 dl/g or less. Also, the acid value is preferably 200 eq/t or less, particularly preferably 50 eq/t or less.

The polyester elastomer (B) used in the present invention can be produced by known methods. For example, a lower alcohol diester of a dicarboxylic acid, an excess amount of a low molecular weight glycol, and a soft segment component are transesterified in the presence of a catalyst, and the resulting reaction product is polycondensed, or a dicarboxylic acid and an excess amount of glycol and A method in which a soft segment component is subjected to an esterification reaction in the presence of a catalyst and the resulting reaction product is polycondensed, or a hard segment is prepared in advance, a soft segment component is added thereto, and randomization is performed by transesterification. method, a method of connecting the hard segment and the soft segment with a chain linking agent, and when poly(ε-caprolactone) is used for the soft segment, addition reaction of the hard segment with the ε-caprolactone monomer may be used.

The content of the polyester elastomer (B) in the polybutylene terephthalate resin composition is 4 to 42% by mass, preferably 5 to 40% by mass, more preferably 15 to 30% by mass. By blending the polyester elastomer (B) within this range, it becomes possible to obtain a polybutylene terephthalate resin composition capable of bonding to a polyester elastomer having practical bonding strength.

[Copolyester resin (C)]
The copolymer polyester resin (C) in the present invention contains 40 mol% or more of ethylene glycol and terephthalic acid and ethylene glycol, when the total acid component is 100 mol% and the total glycol component is 100 mol%. or a resin in which 1,4-butanediol accounts for 40 mol% or more and the total of terephthalic acid and 1,4-butanediol accounts for 80 to 180 mol%. Copolymerization components include isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalenedicarboxylic acid, diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-butanediol, 1 , 2-propanediol, 1,3-propanediol, ethylene glycol and 2-methyl-1,3-propanediol. Ethylene glycol and 1,4-butanediol can be copolymerization components in the polyester resin not contained in the main component.

Copolyester resin (C) is preferably a polyester resin obtained by copolymerizing ethylene terephthalate units or butylene terephthalate units with at least one of alkyl side chain-containing glycol and isophthalic acid, and is preferably amorphous. . Glycols containing alkyl side chains include neopentyl glycol, 1,2-propanediol, and 2-methyl-1,3-propanediol. Among them, from the viewpoint of various properties, preferred copolymerization components are components that reduce crystallinity, such as neopentyl glycol and isophthalic acid.

The copolymerization ratio of the alkyl side chain-containing glycol is preferably 20 to 60 mol%, more preferably 25 to 50 mol%, when the total glycol component constituting the copolymer polyester resin (C) is 100 mol%.
The copolymerization ratio of isophthalic acid is preferably 20 to 60 mol%, more preferably 25 to 50 mol%, based on 100 mol% of all acid components constituting the copolymerized polyester resin (C).

The degree of polymerization of the copolymer polyester resin (C) varies slightly depending on the specific copolymer composition, but the intrinsic viscosity (0.1 g sample is dissolved in 25 ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4) and measured at 30° C. using an Ubbelohde viscosity tube) is preferably 0.4 to 1.5 dl/g, more preferably 0.4 to 1.3 dl/g. If it is less than 0.4 dl/g, the toughness is lowered, and if it exceeds 1.5 dl/g, the fluidity is lowered, which is not preferred.

The content of the copolymer polyester resin (C) in the polybutylene terephthalate resin composition is 0 to 50% by mass, preferably 0 to 30% by mass, more preferably 0 to 25% by mass, More preferably, it is 10 to 25% by mass. By blending the copolymer polyester resin (C) within this range, when compared with a polybutylene terephthalate resin composition containing the same amount of the polyester elastomer (B), by adding the copolymer polyester resin (C) It is possible to increase the bonding strength. If the content exceeds 50% by mass, the bonding strength is improved, but the heat resistance is lowered, which is not preferable.

[Glass fiber (D)]
The polybutylene terephthalate resin composition of the present invention contains glass fibers (D) having a non-circular fiber cross section. Although the average fiber length of the glass fiber (D) is not particularly limited, it is preferably selected in the range of, for example, 0.1 to 20 mm, more preferably 0.3 to 5 mm. If the average fiber length is less than 0.1 mm, a sufficient reinforcing effect may not be exhibited, and if it exceeds 20 mm, molding of the resulting polybutylene terephthalate resin composition may become difficult.

The glass fiber (D) is preferably a flat cross-section glass fiber or a cocoon-shaped cross-section glass fiber having an average ratio of the major axis to the minor axis (major axis/minor axis) of the fiber cross section of 1.5 to 8. . The use of such glass fibers is preferable from the viewpoint of bending strength and impact strength, and also from the viewpoint of good appearance of the molded product and good dimensional stability such as warpage. The average value of the ratio of the major axis to the minor axis (major axis/minor axis) of the fiber cross section of the flat cross section glass fiber is more preferably 1.6 to 7, more preferably 1.7 to 6, and particularly preferably 1.8 to 5.

Although the average fiber diameter of the glass fiber (D) is not particularly limited, it is preferably selected in the range of, for example, 1 to 100 μm, more preferably 2 to 50 μm, still more preferably 3 to 30 μm, particularly preferably 5 to 20 μm. Glass fibers with an average fiber diameter of less than 1 μm are not easy to manufacture and may be costly, while glass fibers with an average fiber diameter of more than 100 μm may have reduced tensile strength. The average fiber diameter when the fiber cross section is non-circular refers to the average fiber diameter when the fiber cross section is converted into a circular shape.

Moreover, it is preferable to use the glass fiber (D) that has been surface-treated with a surface treatment agent such as a coupling agent. A glass fiber to which a surface treatment agent is attached tends to be excellent in durability, resistance to moist heat, resistance to hydrolysis, and resistance to heat shock, and thus is preferable.

As the surface treatment agent, any conventionally known one can be used, and specifically, silane coupling agents such as aminosilane, epoxysilane, allylsilane, and vinylsilane are preferred. Among these, aminosilane-based surface treatment agents are preferred, and specifically, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane and γ-(2-aminoethyl)aminopropyltrimethoxysilane are preferred. Examples include:

In addition, as the surface treatment agent, epoxy resins such as novolak type epoxy resins, bisphenol A type epoxy resins, and the like are preferably used. Among them, a novolak type epoxy resin is more preferable. The silane-based surface treatment agent and the epoxy resin may be used alone or in combination, and it is also preferable to use both together.

The content of the glass fiber (D) in the polybutylene terephthalate resin composition is 1 to 60% by mass, preferably 5 to 55% by mass, more preferably 10 to 55% by mass. By blending the glass fiber (D) within this range, it is possible to obtain a polybutylene terephthalate resin composition capable of bonding to a polyester elastomer with improved heat resistance and rigidity without impairing the bonding strength with the polyester elastomer. becomes.

[Other additives]
In addition, the polybutylene terephthalate resin composition of the present invention may contain various known additives, if necessary, as long as the properties of the present invention are not impaired. Examples of known additives include colorants such as pigments, release agents, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, modifiers, antistatic agents, flame retardants, dyes, and the like. mentioned.
Examples of release agents include long-chain fatty acids or esters thereof, metal salts thereof, amide compounds, polyethylene wax, silicon, polyethylene oxide and the like. The long-chain fatty acid preferably has 12 or more carbon atoms, and examples thereof include stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, etc. Partially or entirely of the carboxylic acid is esterified with monoglycol or polyglycol. or may form a metal salt. Examples of amide compounds include ethylenebisterephthalamide and methylenebisstearylamide. These release agents may be used alone or as a mixture.
These various additives can be contained up to a total of 5% by mass based on 100% by mass of the polybutylene terephthalate resin composition. That is, the total of (A), (B), (C) and (D) is preferably 95 to 100% by mass in 100% by mass of the polybutylene terephthalate resin composition.

[Polybutylene terephthalate resin composition]
As a production method for producing the polybutylene terephthalate resin composition of the present invention, after blending the above composition in an arbitrary blending order, they are mixed by a tumbler or a Henschel mixer and melt-kneaded. The melt kneading method can be any method known to those skilled in the art, and a single screw extruder, a twin screw extruder, a kneader, a Banbury mixer, rolls, etc. can be used, but especially a twin screw extruder is used. preferably. In addition, in order to remove volatile components and decomposed low-molecular-weight components during processing, it is desirable to perform suction with a vacuum pump between the side port of the glass fiber input portion and the die head at the tip of the extruder.

The polybutylene terephthalate resin composition of the present invention is used for moldings to which a polyester elastomer is welded, and particularly for moldings to which a polyester elastomer is welded by insert molding.
The polybutylene terephthalate resin composition of the present invention can be formed into a molded article by a known molding method such as injection molding. This molded body can be used for the composite material described below.

[Composite materials]
A composite molded article in which a molded article made of the polybutylene terephthalate resin composition of the present invention and a polyester elastomer are welded together will be described below. This composite molded article is obtained by disposing a molded article made of a polybutylene terephthalate resin composition in a mold as an insert material and welding a polyester elastomer by injection molding. In insert molding, a material (insert material) placed in a mold is called a primary material, and in the present invention, a molded article made of a polybutylene terephthalate resin composition corresponds to this. The material injected into the mold in which the insert material is arranged is called a secondary material, and in the present invention polyester elastomer corresponds to it.

The polyester elastomer of the secondary material may be the same as or different from the polyester elastomer (B) used in the primary material described above. The polyester elastomer of the secondary material is not particularly limited, but the polyester elastomer (B) used for the primary material described above can be used. The hardness (surface hardness) of the secondary polyester elastomer is preferably 25 to 40 Shore D hardness. It is a preferred embodiment to use the same kind of soft segment in the polyester elastomer of the secondary material and the polyester elastomer (B) used in the primary material.

The reason why insert molding exhibits excellent bondability (weldability) between a molded article composed of a polybutylene terephthalate resin composition as a primary material and a polyester elastomer as a secondary material is considered as follows. A polyester elastomer in which the polyester elastomer (B) dispersed in a sea-island structure in the polybutylene terephthalate resin (A) is introduced as a secondary material by containing a specific amount of the polyester elastomer (B) in the primary material. It is thought that the polyester elastomer dispersed on the primary material side and the polyester elastomer on the secondary material side are mixed to provide adhesiveness. It is believed that the inclusion of the copolymerized polyester resin (C) facilitates the movement of the polybutylene terephthalate resin (A) in the primary material, thereby facilitating mixing.

The composite material of the present invention can be used for air ducts, bearings, rollers, covers, various housings, connectors, grips, casters, etc. by taking advantage of its properties.

EXAMPLES The present invention will be specifically described using Examples and Comparative Examples, but the present invention is not limited to these. In addition, the measured values described in the examples were measured by the following methods.

(1) Intrinsic viscosity of polybutylene terephthalate resin and copolymer polyester resin A 0.1 g sample was dissolved in 25 ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4) and measured at 30°C using an Ubbelohde viscometer. did. (Unit: dl/g)
(2) Reduced Viscosity of Polyester Elastomer A 0.05 g sample was dissolved in 25 ml of a mixed solvent (phenol/tetrachloroethane=60/40 (mass ratio)) and measured at 30° C. using an Ostwald viscometer. (Unit: dl/g)
(3) Hardness of polyester elastomer (surface hardness)
Measured according to JIS K7215 (-1986). As the test piece, three injection-molded products (length 100 mm, width 100 mm, thickness 2 mm) prepared at a cylinder temperature of 240 ° C. and a mold temperature of 50 ° C. were stacked, and a measurement pressure of 5000 g and a type D indenter were used. was measured with a durometer using , and the value 5 seconds after the start of measurement was taken as D hardness (Shore D hardness).

(4) Preparation of semi-dumbbells of polybutylene terephthalate resin composition for insert molding Polybutylene terephthalate resin composition pellets obtained by compounding were injected using an injection molding machine (J110AD-110H manufactured by Japan Steel Works, Ltd.), and the cylinder temperature was 230. C., mold temperature=50.degree.
(5) Insert molding After mounting the ISO tensile test half dumbbell obtained above in the ISO tensile test dumbbell molding mold cavity, the remaining dumbbell part is injection molded with a polyester elastomer at a cylinder temperature of 230 ° C., polybutylene terephthalate resin An ISO tensile test dumbbell was obtained in which the composition and the polyester elastomer were joined (welded) at the center. Polyester elastomer (B-2) shown below was used as the polyester elastomer.
(6) Evaluation of bondability An ISO tensile test dumbbell in which the polybutylene terephthalate resin composition and the polyester elastomer obtained above were bonded at the center was measured according to ISO-527-1.2, and the dumbbell was broken. Elongation (%) was determined, and the state of the polyester elastomer was evaluated.
In the above tensile test, when the test piece with an elongation of 30% or more was confirmed, the polyester elastomer was adhered to the joint portion of the polybutylene terephthalate composition, and a trace of joint was confirmed. Therefore, when the elongation is 30% or more, it was determined that the joint strength was sufficient at the stress-generating portion.

(7) Flexural strength, flexural modulus Measured according to ISO-178.
(8) Charpy impact strength Measured according to JIS K7111.
(9) Appearance evaluation After drying the pellets obtained by the above manufacturing method at 130 ° C. for 4 hours, an injection molding machine (J110AD-110H manufactured by Japan Steel Works, Ltd.) was used, with a cylinder temperature of 250 ° C. and a mold temperature of 60. 100 x 100 x 2 mmt injection-molded test pieces molded under conditions of °C were visually observed and evaluated according to the following criteria.
Poor: White spots are present on the entire surface of the test piece. Good: Slight white spots are present on the entire surface of the test piece. Best: Almost no white spots are observed on the entire surface of the test piece.

The ingredients used in Examples and Comparative Examples are shown below.
polybutylene terephthalate resin (A);
(A-1) Polybutylene terephthalate resin: manufactured by Toyobo Co., Ltd. Intrinsic viscosity 0.83 dl / g
(A-2) Polybutylene terephthalate resin: manufactured by Toyobo Co., Ltd. Intrinsic viscosity 1.30 dl / g

polyester elastomer (B);
(B-1) Terephthalic acid (TPA)//1,4-butanediol (BG)/polyoxytetramethylene glycol (PTMG; number average molecular weight 1000) is 100//71.8/28.2 (mol%) polyester elastomer: melting point of 172° C., reduced viscosity of 2.22 dl/g, acid value of 35 eq/ton, D hardness of 38
(B-2) Polyester elastomer with 100//75/25 (mol%) of terephthalic acid (TPA)//1,4-butanediol (BG)/polyoxytetramethylene glycol (PTMG; number average molecular weight 2000): The melting point is 180°C, the reduced viscosity is 2.50 dl/g, the acid value is 21 eq/ton, and the D hardness is 31.

other elastomers;
(B-3) Acrylic elastomer: Modiper A6300 (ethylene ethyl acrylate (EEA)-graft-butyl acrylate/methyl methacrylate (P (BA/MMA)) manufactured by NOF Corporation)

Copolyester resin (C);
(C-1) Copolymer having a composition ratio of TPA//EG (ethylene glycol)/NPG (neopentyl glycol) = 100//70/30 (mol%): Trial of Vylon (registered trademark) manufactured by Toyobo Co., Ltd. Work, glass transition temperature 75°C, intrinsic viscosity 0.83 dl/g
(C-2) Copolymer having a composition ratio of TPA/IPA (isophthalic acid)//EG/NPG (neopentyl glycol) = 50/50//50/50 (mol%): Vylon (registered Trademark) prototype, glass transition temperature 67°C, intrinsic viscosity 0.53 dl/g

glass fiber (D);
(D-1) Glass fiber (average fiber length 3 mm): CSG3PL830F, flat cross section, ratio of major axis to minor axis: 2 (minor axis 10 μm, major axis 20 μm) (manufactured by Nittobo)
(D-2) Glass fiber (average fiber length 3 mm): ECS303T, flat cross section, ratio of major axis to minor axis: 3.5 (minor axis 8 μm, major axis 28 μm) (manufactured by CPIC)
(D-3) Glass fiber (average fiber length 3 mm, average fiber diameter 11 μm): T-120H, round cross section, ratio of major axis to minor axis: 1 (manufactured by Nippon Electronic Glass Co., Ltd.)

other additives;
Antioxidant 1: Irganox 1010 (manufactured by Ciba Specialty Chemicals)
Antioxidant 2: Seenox 412S (manufactured by Shipro Kasei Co., Ltd.)
Release agent: WE40 (manufactured by Clariant Japan)

<Examples 1 to 13, Comparative Examples 1 to 9>
After each component was blended in a tumbler so as to have the composition shown in Table 1, the mixture was melt-kneaded in a twin-screw extruder (using STS35 manufactured by Coperion) to obtain composition pellets.
After drying the obtained composition pellets, they were evaluated by the method described above. Physical property evaluations (7) to (9) were performed on the polybutylene terephthalate resin composition, and bondability evaluation (6) was performed on the composite molded product. The results are shown in Table 1.

From Table 1, it is possible to improve the appearance by using glass fibers with modified cross sections from the composite molded articles obtained from the polybutylene terephthalate resin compositions of Examples 1 to 5 and Comparative Examples 6 to 9. I know there is. From Examples 6 and 7, the more the amount of the polyester elastomer blended, the more the adhesiveness was improved, and the appearance was also in a good state. Since the increase in the content of the polyester elastomer improves the adhesiveness, it is understood that the polyester elastomer dispersed in the sea-island structure contributes to the adhesiveness. It can be seen that it is getting better.
In the molded articles obtained from the polybutylene terephthalate resin compositions of Examples 8 to 10, it can be confirmed that the adhesivity is improved by using the copolyester resin together. This is because Tc2 of the polybutylene terephthalate resin, which is the sea portion of the sea-island structure, is lowered during adhesion, thereby facilitating adhesion between the polyester elastomers. Furthermore, it is clear that the combined use of the modified cross-section glass fiber and the copolymerized polyester resin made it possible to further improve the appearance.
From Examples 11 to 13, it can be seen that the various effects are not limited to the use of specific materials.
From Comparative Examples 1 to 5, it can be seen that the various effects described above are maximized when all the materials specified in the present invention are used in combination.

As described above, by adding a predetermined amount or more of the polyester elastomer to the polybutylene terephthalate resin composition of the primary material, sufficient bonding (welding) with the polyester elastomer of the secondary material is achieved while maintaining the properties of the polybutylene terephthalate resin. It is possible to give Furthermore, by adding a copolymerized polyester resin, Tc2 is lowered, and the molecular motion of the polybutylene terephthalate resin is activated even with the same amount of heat when welding the polyester elastomer. improving. In addition, when using glass fibers, the average value of the ratio of the major axis to the minor axis (major axis / minor axis) of the fiber cross section is 1.5 to 8. By using glass fibers with a flat cross section or a cocoon-shaped cross section, the appearance can be improved. It has been found that it can be injection molded without damage.

The resin composition of the present invention has practically sufficient bonding strength compared to conventional polybutylene terephthalate resin compositions, and is therefore useful as a molding material for moldings that can be bonded to a polyester elastomer by insert molding.

Claims (4)

Polybutylene terephthalate resin (A) 20 to 95% by mass, polyester elastomer (B) 4 to 42% by mass, copolymer polyester resin (C) 0 to 50% by mass, and glass fiber (D) having a non-circular fiber cross section A polybutylene terephthalate resin composition containing 1 to 60% by mass, wherein the glass fiber (D) has an average ratio of the major axis to the minor axis (long axis/short axis) of the fiber cross section of 1.5 to 8 A polybutylene terephthalate resin composition which is a flat cross-section glass fiber or a cocoon-shaped cross-section glass fiber and is for a molded article to which a polyester elastomer is welded. 2. The polybutylene terephthalate resin composition according to claim 1 , wherein the copolymer polyester resin (C) is a polyester resin obtained by copolymerizing ethylene terephthalate units or butylene terephthalate units with at least one of alkyl side chain-containing glycols and isophthalic acid. . A composite molded article obtained by welding a molded article comprising the polybutylene terephthalate resin composition according to any one of claims 1 and 2 and a polyester elastomer. A method for producing a composite molded article, wherein a molded article made of the polybutylene terephthalate resin composition according to any one of claims 1 and 2 is placed in a mold as an insert material, and a polyester elastomer is welded by injection molding.