JP2021161373A - Polyester resin composition, molding, and composite molding - Google Patents

Abstract

To provide a polyester resin composition that is favorable in injection moldability, is excellent in mechanical strength and can realize stable laser weldability by controlling high laser transmittance at each part of a molding.SOLUTION: A polyester resin composition characterized in that the degree of crystallinity calculated by the following method using a high-speed calorimetry is 15% or larger. Calculation method: the degree of crystallinity is calculated from a curve obtained when, by using a high speed calorimetry, the polyester resin composition is heated from 30°C to 260°C at 10000°C/second, followed by keeping at 260°C for 0.1 second, further followed by cooling to 80°C at 5000°C/second, further followed by keeping at 80°C for 0.1 second, further followed by cooling to -70°C at 5000°C/second, and still further followed by heating to 260°C at 1000°C/second.SELECTED DRAWING: None

Description

The present invention relates to a polyester resin composition having excellent injection moldability and laser weldability, a molded product, and a composite molded product comprising the same.

Polyester resins, especially polybutylene terephthalate resins, utilize their excellent injection moldability, mechanical properties, heat resistance, electrical properties, chemical resistance, etc. in the fields of mechanical parts, electrical / communication parts, automobile parts, etc. It is widely used as an injection molded product. However, although the molding efficiency of an injection-molded product is good, the shape is limited in terms of its flow characteristics and mold structure, and it is difficult to mold an injection-molded product that is too complicated.

Conventionally, in the joining of each part due to the complication of the product shape, joining with an adhesive, mechanical joining with bolts and the like has been performed. However, bonding with an adhesive does not have sufficient strength, and mechanical joining with bolts or the like has problems such as cost, labor for fastening, and weight increase of the product. On the other hand, external heat welding such as laser welding and hot plate welding, friction heat welding such as vibration welding, and ultrasonic welding can be performed in a short time, and since no adhesive or metal parts are used, it is necessary. Since problems such as cost, product weight increase, and environmental pollution do not occur, welding by these methods is increasing.

Laser welding, which is one of the external heat welding methods, is a method of irradiating a superposed resin molded body with laser light, transmitting one through the other, and absorbing the other to melt and weld the resin. Three-dimensional welding. It is a construction method that is spreading to a wide range of fields by taking advantage of the fact that it is possible to perform non-contact processing, that there is no burr generation, and so on.

Polybutylene terephthalate-based resins, which are widely used in various applications because of their high dimensional stability and low water absorption, have extremely low laser light transmittance compared to polyamide resins, and polybutylene terephthalate-based resins are on the laser beam transmitting side. When the laser welding method is applied to the molded product, the thickness of the molded product is very strict due to its low laser light transmittance, and it is necessary to reduce the wall thickness in order to improve the laser light transmittance. The degree of freedom in product design was small.

In addition to the laser beam transmittance, if there is a large variation in the transmittance between the parts of the molded product on the laser beam transmitting side, it may cause welding failure. Therefore, in order to perform stable laser welding, the laser beam transmitting side should be used. It is desirable to control the transmittance between the parts of the molded product to be used.

In response to the above problems, Patent Document 1 discloses a method of adding an alkali metal salt of a fatty acid to a polyester resin in order to improve the transparency of a laser beam.

Further, Patent Document 2 discloses a method of obtaining a laser-transmissive thermoplastic resin having good mechanical strength by filling a thermoplastic resin with a specific glass fiber.

Japanese Patent Application Laid-Open No. 2014-512420 Japanese Unexamined Patent Publication No. 2013-53316

However, in Patent Document 1, although the transmittance required for laser welding is good, the transmittance is liable to fluctuate, and due to the influence of the variation in the transmittance between the parts of the molded product, welding failure may occur. There is a problem that it is difficult to obtain stable laser weldability. Further, since Patent Document 2 originally uses a polyester resin having low laser transmittance, the transmittance is not sufficient. In addition, there is a problem in injection moldability, and a laser-transparent material having further excellent productivity has been required.

Therefore, an object of the present invention is a polyester resin composition having good injection moldability, excellent mechanical strength, and realizing stable laser weldability by controlling high laser permeability at each part of a molded product. It is an object of the present invention to provide a molded article molded using the composition and a composite molded article using this molded article.

In order to solve the above problems, the present invention has the following configuration.
(1) A polyester resin composition characterized in that the crystallinity calculated by the following method using high-speed calorimetry is 15% or more.
Calculation method: Using high-speed crystallization, the polyester resin composition was heated from 30 ° C. to 260 ° C. at 10000 ° C./sec, held at 260 ° C. for 0.1 second, and then cooled to 80 ° C. at 5000 ° C./sec. Crystallinity calculated from the curve obtained when the temperature was maintained at 80 ° C. for 0.1 seconds, cooled to −70 ° C. at 5000 ° C./sec, and then raised to 260 ° C. at 1000 ° C./sec.
(2) The polyester resin composition according to (1), wherein the average length in the length direction of the linear structure observed using a transmission electron microscope is 150 nanometers or less.
(3) With respect to 100 parts by mass of the polyester resin (A), the glass fiber (B) is contained in an amount of more than 0 and 100 parts by mass or less, and the metal salt compound (C) contains 50 to 50 metal ions per 1 kg of the polyester resin. The polyester resin composition according to (1) or (2), which comprises a concentration of 150 mmol.
(4) The polyester resin composition according to (3), wherein the terminal carboxyl group concentration of the polyester resin (A) is 20 eq / t or less.
(5) The polyester resin composition according to (3) or (4), wherein the flatness of the glass fiber (B) calculated by the following formula is 1 to 2.
Flatness = major axis / minor axis of glass fiber cross section (6) The metal salt compound (C) is an aliphatic carboxylic acid at least one selected from sodium propionate, sodium caprylate, sodium stearate, and a mixture thereof. The polyester resin composition according to any one of (3) to (5), which is a sodium acid salt.
(7) A molded product comprising the polyester resin composition according to any one of (1) to (6).
(8) A composite molded product obtained by laser welding the molded product according to (7).

The characteristics of the polyester resin composition of the present invention are that it is excellent in injection moldability and that high laser permeability is highly controlled at different parts in the molded product of this resin composition. Therefore, it is useful for laser welding of resin molded products for various purposes, especially for laser-transmitted molded products.

This is a laser light transmission evaluation test piece having a length L of each side of 80 mm and a thickness D of 2 mm.

<Polyester resin (A)>
The polyester resin (A) used in the present invention is (a) a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, (b) a hydroxycarboxylic acid or an ester-forming derivative thereof, and (c) a lactone. It is a polymer or copolymer having one or more selected from the above as a main structural unit.

Examples of the dicarboxylic acid or an ester-forming derivative thereof include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, and anthracenedicarboxylic acid. Aromatic dicarboxylic acids such as 4,4'-diphenyl ether dicarboxylic acid, 5-tetrabutylphosphonium isophthalic acid, 5-sodium sulfoisophthalic acid, diphenic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecandione Examples thereof include aliphatic dicarboxylic acids such as acids, malonic acids, glutaric acids and dimer acids, alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acids and 1,4-cyclohexanedicarboxylic acids, and ester-forming derivatives thereof. ..

Examples of the diol or an ester-forming derivative thereof include aliphatic glycols having 2 to 20 carbon atoms, that is, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1, Aromas such as 6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, dimerdiol, or long-chain glycols with a molecular weight of 200 to 100,000, such as polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, etc. Group dioxy compounds such as 4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, bisphenol A, bisphenol S, bisphenol F, bisphenol-C and ester-forming derivatives thereof.

(B) Examples of the polymer or copolymer having a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as a structural unit include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, and poly. Hexylene terephthalate, polyethylene terephthalate, polypropylene isophthalate, polybutylene isophthalate, polycyclohexanedimethylene isophthalate, polyhexylene isophthalate, polyethylene naphthalate, polypropylene naphthalate, polybutylene naphthalate, polyethylene isophthalate / terephthalate, polypropylene Isophthalate / terephthalate, polybutyleneisophthalate / terephthalate, polyethylene terephthalate / naphthalate, polypropylene terephthalate / naphthalate, polybutylene terephthalate / naphthalate, polybutylene terephthalate / decandicarboxylate, polyethylene terephthalate / cyclohexanedimethylene terephthalate, polyethylene terephthalate / 5- Sodium sulfoisophthalate, polypropylene terephthalate / 5-sodium sulfoisophthalate, polybutylene terephthalate / 5-sodium sulfoisophthalate, polyethylene terephthalate / polyethylene glycol, polypropylene terephthalate / polyethylene glycol, polybutylene terephthalate / polyethylene glycol, polyethylene terephthalate / polytetra Methylene glycol, polypropylene terephthalate / polytetramethylene glycol, polybutylene terephthalate / polytetramethylene glycol, polyethylene terephthalate / isophthalate / polytetramethylene glycol, polypropylene terephthalate / isophthalate / polytetramethylene glycol, polybutylene terephthalate / isophthalate / poly Tetramethylene glycol, polyethylene terephthalate / succinate, polypropylene terephthalate / succinate, polybutylene terephthalate / succinate, polyethylene terephthalate / adipate, polypropylene terephthalate / adipate, polybutylene terephthalate / adipate, polyethylene terephthalate / sebacate, polypropylene terephthalate / sevacate , Polybutylene terephthalate / sebacate, polyethylene terephthalate / isophthalate / adipate, polypropylene terephthalate / isophthalate / adipate, polybutylene terephthalate / isophthalate / succinate, polybutylene terephthalate / isophthalate / adipate, polybutylene terephthalate / isophthalate / sevacate, etc. Aromatic polyester resin, polyethylene oxalate, polypropylene oxalate, polybutylene oxalate, polyethylene succinate, polypropylene succinate, polypropylene succinate, polyethylene adipate, polypropylene adipate, polybutylene adipate, polyneopentyl glycol adipate, polyethylene seva Examples thereof include aliphatic polyester resins such as kate, polypropylene sebacate, polybutylene sebacate, polyethylene succinate / adipate, polypropylene succinate / adipate, and polybutylene succinate / adipate. Among them, aromatic polyester resin is preferable, any one selected from polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate or a copolymer thereof is more preferable, and polybutylene terephthalate or a copolymer thereof is further preferable.

(B) Examples of the hydroxycarboxylic acid or its ester-forming derivative include glycolic acid, lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid, p-hydroxybenzoic acid, 6-. Examples thereof include hydroxy-2-naphthoic acid and ester-forming derivatives thereof, and examples of the polymer or copolymer having these as structural units include polyglycolic acid, polylactic acid, polyglycolic acid / lactic acid, and polyhydroxybutyric acid /. Examples thereof include aliphatic polyester resins such as β-hydroxybutyric acid / β-hydroxyvaleric acid.

Examples of the above (c) lactone include ε-caprolactone, valerolactone, propiolactone, undecalactone, 1,5-oxepan-2-one, γ-butyrolactone, and the like, and polymers having these as structural units. Alternatively, examples of the copolymer include polycaprolactone, polyvalerolactone, polypropiolactone, poly-γ-butyrolactone, polycaprolactone / valerolactone and the like.

Among these, (a) a polymer or a copolymer having (a) a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as a main structural unit is preferable, and an aromatic dicarboxylic acid or an ester-forming derivative thereof is used. A polymer or copolymer having an aliphatic diol or an ester-forming derivative thereof as a main structural unit is more preferable, and an aliphatic diol or an aliphatic diol selected from terephthalic acid or an ester-forming derivative thereof and ethylene glycol, propylene glycol, butanediol or a terephthalic acid or an ester-forming derivative thereof. Polymers or copolymers containing an ester-forming derivative as a main structural unit are more preferable, and among them, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polypropylene naphthalate, and polybutylene naphthalate. , Polyethylene terephthalate / terephthalate, polypropylene isophthalate / terephthalate, polybutylene isophthalate / terephthalate, polyethylene terephthalate / naphthalate, polypropylene terephthalate / naphthalate, polybutylene terephthalate / naphthalate and other aromatic polyester resins are preferable, polyethylene terephthalate, polypropylene terephthalate, Polybutylene terephthalate is particularly preferable, and polybutylene terephthalate is particularly preferable.

In the present invention, (a) terephthalic acid or an ester-forming derivative thereof with respect to the total dicarboxylic acid in the polymer or copolymer having the above (a) dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as a main structural unit. The ratio of the above is preferably 30 mol% or more, and more preferably 40 mol% or more.

In the present invention, the terminal group of the polyester resin (A) is not particularly limited and may have a terminal carboxyl group, a terminal hydroxyl group, or other terminal groups, but is excellent in laser transmittance. The terminal carboxyl group concentration is preferably 50 eq / t or less, more preferably 30 eq / t or less, further preferably 20 eq / t or less, and particularly preferably 15 eq / t or less.

The viscosity of the polyester resin (A) used in the present invention is not particularly limited as long as it can be melt-kneaded, but in terms of moldability, the intrinsic viscosity of the o-chlorophenol solution measured at 25 ° C. is 0.36. It is preferably in the range of ~ 1.60 dl / g, and more preferably in the range of 0.50 to 1.50 dl / g.

The melting point of the polyester resin (A) used in the present invention is not particularly limited as long as it can be melt-kneaded, but it is preferably 200 ° C. or higher in terms of heat resistance and mechanical strength, and is excellent in melt processability. It is more preferably 215 ° C. or higher, and even more preferably 220 ° C. or higher. The upper limit of the melting point is not particularly limited, but it is preferably 280 ° C. or lower, and more preferably 270 ° C. or lower, in terms of excellent melt processability. If the melting point is less than 210 ° C, there is a problem of reduced heat resistance, while if the melting point exceeds 280 ° C, the crystallinity and crystal size become extremely large, so excessive heating during melt processing is required, and the polyester resin. There is a possibility that the decomposition of the resin will occur at the same time. The melting point referred to here is a temperature decrease rate of 20 after raising the temperature from 30 ° C. to 280 ° C. at a temperature rise rate of 20 ° C./min and holding at 280 ° C. for 3 minutes using a differential scanning calorimeter (DSC). This is the peak top temperature of the endothermic peak observed when the temperature is lowered from 280 ° C. to 30 ° C. at ° C./min and then raised from 30 ° C. to 280 ° C. at a heating rate of 20 ° C./min.

Further, in the present invention, the amount of heat of crystal fusion represented by the area of the endothermic peak measured under the above conditions using the differential scanning calorimeter (DSC) is 20 J / g or more in that it is excellent in heat resistance. It is preferably 30 J / g or more, and more preferably 40 J / g or more. The upper limit of the amount of heat for melting the crystal is not particularly limited, but it is preferably 60 J / g or less, and more preferably 50 J / g or less in terms of excellent melt processability.

The method for producing the polyester resin (A) used in the present invention is not particularly limited, and can be produced by an ordinary polycondensation method, ring-opening polymerization method, or the like, and may be either batch polymerization or continuous polymerization. Further, any of the methods of undergoing an ester exchange reaction and a polycondensation reaction and a reaction by direct polymerization can be applied, but the amount of terminal carboxyl groups can be reduced and the laser permeability is excellent, so that they are continuous. Polymerization is preferable, and direct polymerization is preferable in terms of cost.

When the (A) polyester resin used in the present invention is (a) a polymer or copolymer obtained by a condensation reaction containing (a) a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as main components. Can be produced by (a) dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof by an esterification reaction or an ester exchange reaction, and then a polycondensation reaction. In order to effectively proceed with the esterification reaction or the ester exchange reaction and the polycondensation reaction, it is preferable to add a polymerization reaction catalyst during these reactions, and specific examples of the polymerization reaction catalyst include methyl ester of titanic acid. Organic titanium such as tetra-n-propyl ester, tetra-n-butyl ester, tetraisopropyl ester, tetraisobutyl ester, tetra-tert-butyl ester, cyclohexyl ester, phenyl ester, benzyl ester, trill ester, or a mixed ester thereof. Compounds, Dibutyltin Oxide, Methylphenyltin Oxide, Tetraethyltin, Hexaethyl Ditin Oxide, Cyclohexahexyl Ditin Oxide, Didodecyltin Oxide, Triethyltin Hydrooxide, Triphenyltin Hydrooxide, Triisobutyltin Acetate, Dibutyltin Diacetate , Diphenyltin dilaurate, monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin sulfide and butylhydroxytin oxide, tin compounds such as methylstannoic acid, ethylstannoic acid, alkylstannonic acid such as butylstannonic acid, zirconium tetra Examples thereof include zirconia compounds such as -n-butoxide, antimony compounds such as antimony trioxide and antimony acetate, and among these, organic titanium compounds and tin compounds are preferable, and tetra-n-propyl ester of titanium acid, Tetra-n-butyl ester and tetraisopropyl ester are preferable, and tetra-n-butyl ester of titanoic acid is particularly preferable. Only one kind of these polymerization reaction catalysts may be used, or two or more kinds thereof may be used in combination. The amount of the polymerization reaction catalyst added is preferably in the range of 0.005 to 0.5 parts by weight, preferably 0.01 to 0.2 parts by weight, based on 100 parts by weight of the polyester resin in terms of mechanical properties, moldability and color tone. The range of parts is more preferable.

The polyester resin (A) of the present invention can be used individually or in combination of two or more.

The resin composition containing the polyester resin (A) of the present invention is heated from 30 ° C. to 260 ° C. at 10000 ° C./sec, held at 260 ° C. for 0.1 second, and then up to 80 ° C. using high-speed crystallization. Endothermic peak observed when cooled at 5000 ° C / sec, held at 80 ° C for 0.1 seconds, cooled to -70 ° C at 5000 ° C / sec, and then heated to 260 ° C at 1000 ° C / sec. _{The crystallinity (X c} ) calculated from the amount of heat of crystal fusion (ΔH _m ) represented by the area of is 15% or more according to the following formula.
Crystallinity (X _c ) = ΔH _m / ΔH _m ⁰ × 100
Here [Delta] H _m ⁰ is a perfect crystal fusion heat of crystal polyester resin (A). By having such a feature, a stable crystal structure is formed at each part of the molded product even under quenching conditions in the injection molding mold, so that the injection moldability is good and each part of the molded product has good injection moldability. Shows stable laser transmission. In the present invention, the crystallinity is preferably 15% or more, more preferably 20% or more. The upper limit is not particularly limited, but it is preferably 60% or less, and more preferably 50% or less in terms of excellent melt processability. Here, high-speed calorimeter is a calorimeter capable of high-speed up-and-down temperature with a sample amount on the order of nanograms by miniaturizing the thermal sensor. Although the ascending / descending temperature that can be followed is limited depending on the type and size of the sample, it has a maximum heating rate of 10000 ° C./sec and a maximum cooling rate of 5000 ° C./sec.

Further, the resin composition containing the polyester resin (A) of the present invention has an average length in the length direction of the linear structure derived from the crystal structure of the polyester resin (A) observed using a transmission electron microscope. It is preferably 150 nanometers or less. Here, the average length of the linear structure in the length direction can be obtained by the following method. Using a resin composition formed so as to have a thickness of 1 mm or more, a sample prepared by cutting out the inside of 50 micrometers or more from the surface thereof is stained with ruthenium tetroxide and observed with a transmission electron microscope. The obtained image is used as an image having a size of 1 μm × 1 μm, and the length direction of 10 arbitrarily selected linear structures is measured for a structure that can be identified by shading, and the average value is used as the average value. By having such a structure, the diffusion of laser light is suppressed in the resin composition, and good laser transparency is exhibited. In the present invention, the average length of the linear structure in the length direction is preferably 150 nanometers or less, more preferably 125 nanometers or less, still more preferably 100 nanometers or less. The lower limit is not particularly limited, but in order to maintain heat resistance, it is preferably 50 nanometers or more.

The method for setting the degree of crystallization of the polyester resin composition calculated by the above method to 15% or more and the average length of the linear structure in the length direction to 150 nanometers or less is not particularly limited, but for example. , An aliphatic carboxylic acid sodium salt is used as the metal salt compound (C) to be blended in the polyester resin composition, the aliphatic carboxylic acid sodium salt is contained in a more preferable range, and an aliphatic carboxylic acid having a more preferable carbon number is used. The use of acid sodium salts can be mentioned.

<Glass fiber (B)>
In the present invention, the polyester resin composition may contain glass fibers (B). The cross section of the glass fiber (B) may be circular or flat, but it is preferable that the glass fiber (B) has a flat cross section in terms of suppressing deformation, reducing warpage, stable laser transmission, and the like. In general, in a composition containing glass fibers, the fibers are oriented in the flow direction during molding, so that the anisotropy of the molding shrinkage rate (percentage of the dimensional difference between the resin molded product and the mold) becomes large, and deformation or warpage occurs. Becomes larger. However, when the cross-sectional shape is flat, the anisotropy of the molding shrinkage is small, and deformation and warpage are likely to be improved.

The glass fiber (B) having a flat cross-sectional shape used in the present invention has a major axis (the longest linear distance in the cross section) and a minor axis (the longest linear distance in the direction perpendicular to the major axis) in a cross section cut at a right angle in the length direction. The flattening ratio represented by the ratio of) is preferably 1 or more and 10 or less. The lower limit of the flatness is preferably 1.3 or more, and more preferably 1.5 or more. The upper limit is preferably 5 or less, more preferably 2.5 or less, and most preferably 2 or less. The specific shape may be an eyebrows, an oval, an ellipse, a semicircle, an arc, a rectangle, or a similar shape thereof, but an oval is particularly preferable in terms of fluidity and low warpage.

When the flatness is 1 or more, deformation and warpage during molding are suppressed, and when it is 10 or less, it is practically difficult to manufacture such a glass fiber. Further, as the glass fiber (B), a hollow fiber can be used for the purpose of reducing the specific gravity. As the cross-sectional area of the glass fiber (B) increases, a sufficient reinforcing effect cannot be obtained. On the other hand, if it is too small, it becomes difficult to manufacture itself, and there is also a problem that it becomes difficult to handle. Cross-sectional area of the glass fiber (B) in the present invention is preferably ^{2 × 10 -5 ~8 × 10 -3} mm 2, more preferably ^{8 × 10 -5 ~8 × 10 -3} mm 2, 8 × 10 - ⁵ to 8 × 10 ^-4 mm ² is more preferred. The length of the glass fiber is not particularly limited, but it is preferable that the length of the glass fiber is short in order to reduce the amount of deformation of the molded product in consideration of the mechanical properties of the molded product and the suppression of deformation. It is preferably 50 to 1000 μm, depending on the required performance. In the glass fiber (B) used in the present invention, it is preferable to use a converging agent or a surface treatment agent, if necessary. The converging agent or surface treatment agent is a functional compound such as an epoxy compound, an isocyanate compound, a silane compound, or a titanate compound. These compounds may be used after being surface-treated or converged in advance, or may be added simultaneously at the time of material preparation. When the glass fiber (B) used in the present invention is flat, the bushing used for discharging the molten glass is spun using a nozzle having an appropriate hole shape such as an oval shape, an elliptical shape, a rectangular shape, or a slit shape. It is prepared by Further, it is prepared by spinning molten glass from a plurality of nozzles provided in close proximity having various cross-sectional shapes (including a circular cross section) and joining the spun molten glass to each other to form a single filament. can.

The blending amount of the glass fiber (B) used in the present invention is preferably more than 0 and 100 parts by mass or less, more preferably 10 to 80 parts by mass, and 20 parts by mass with respect to 100 parts by mass of the polyester resin (A). ~ 50 parts by mass is more preferable. In order to exhibit mechanical strength and low warpage, it is preferable to blend glass fiber (B). Further, by setting the amount to 100 parts by weight or less, the fluidity at the time of molding can be maintained.

<Metal salt compound (C)>
In the present invention, good crystal nucleation is formed by containing the metal salt compound (C) at a concentration of 50 to 150 mmol per 1 kg of the polyester resin with respect to 100 parts by mass of the polyester resin (A). It is preferable in that.

In the present invention, the metal salt compound (C) is an aliphatic carboxylate metal salt, an alicyclic carboxylic acid metal salt, an aromatic carboxylic acid metal salt, a sulfonic acid metal salt, an amide sulfonic acid metal salt, or a phosphate metal salt. , Phosphate ester metal salt, borate metal salt, etc., or a mixture thereof. In terms of excellent crystallization properties, an aliphatic carboxylic acid metal salt having 2 to 50 carbon atoms, an alicyclic carboxylic acid metal salt having 7 to 60 carbon atoms, an aromatic carboxylic acid metal salt having 7 to 60 carbon atoms, and a carbon number of carbon atoms. 1 to 50 aliphatic sulfonic acid metal salts, 6 to 60 carbon atoms alicyclic sulfonic acid metal salts, 6 to 60 carbon atoms aromatic sulfonic acid metal salts, 1 to 50 carbon atoms aliphatic phosphoric acid ester metals Examples thereof include one or a mixture of two or more selected from a salt, an alicyclic phosphate metal salt having 6 to 60 carbon atoms, and an aromatic phosphate metal salt having 6 to 60 carbon atoms. In addition, an aliphatic carboxylate metal salt having 2 to 40 carbon atoms and an alicyclic carboxylate metal salt having 7 to 40 carbon atoms are exhibited in terms of excellent crystallization characteristics, good injection moldability and laser permeability. It is preferably one or a mixture of two or more selected from an aromatic carboxylic acid metal salt having 7 to 40 carbon atoms, an aliphatic carboxylic acid metal salt having 2 to 30 carbon atoms, and an aromatic metal salt having 7 to 30 carbon atoms. It is more preferably one or a mixture of two or more selected from the carboxylic acid metal salts, and an aliphatic carboxylic acid metal salt having 2 to 25 carbon atoms is particularly preferable.

An aliphatic carboxylic acid is a compound in which a carboxyl group is added to a linear or branched aliphatic group, and other components such as an unsaturated group, an alicyclic group or a hydroxyl group, and a phosphate ester group are part of the bond. It may have a substituent.

As the aliphatic carboxylic acid, preferably, propionic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, caproic acid, lauric acid, mystic acid, palmitic acid, margaric acid, stearic acid, oleic acid and linoleic acid. , Montanoic acid and the like.

Further, in the present invention, an aliphatic carboxylic acid metal salt having 3 to 20 carbon atoms is preferable, and an aliphatic carboxylic acid metal having 3 to 10 carbon atoms is preferable in that the affinity with the polyester resin (A) is good. It is more preferably a salt, and particularly preferably an aliphatic carboxylic acid metal salt having 3 to 5 carbon atoms.

In the present invention, the metal species of the metal salt compound (C) is not particularly limited, and any metal species may be used. Lithium, potassium, sodium, magnesium, calcium, aluminum, strontium, titanium, manganese, iron, zinc, silicon, Metal salts selected from zirconium, strontium, barium and the like can be mentioned. Potassium, lithium, and sodium are preferable because they are excellent in crystallization characteristics, they show good injection moldability and laser permeability, and they are also excellent in mechanical properties, and sodium is more preferable because they are particularly excellent in crystallization promoting effect.

The blending amount of the metal salt compound (C) in the present invention is preferably contained at a concentration of 50 to 150 mmol of metal ions with respect to 1 kg of the polyester resin. When it is 50 mmol or more, the laser transmittance of the molded product made of the polyester resin composition can be maintained, and the variation in the transmittance between the parts of the molded product can be suppressed. Further, when the metal salt compound (C) is blended at a concentration of 150 mmol or less with respect to 1 kg of the polyester resin, the polyester resin composition is decomposed by the catalytic action of the metal salt compound, and the molecular weight and mechanical strength are lowered. Can be suppressed. The blending amount of the metal salt compound (C) is preferably contained at a concentration of 50 to 150 mmol, more preferably 50 to 120 mmol, and 50 to 100 mmol per 1 kg of the polyester resin (A). It is more preferable to include it in a concentration.

In the present invention, as the metal salt compound (C), it is preferable to use sodium propionate, sodium caprylate, sodium stearate, and at least one aliphatic sodium aliphatic carboxylic acid salt selected from a mixture thereof. By using these compounds containing sodium ions, high injection moldability and laser transparency improving effect can be obtained.

<Other additives>
Further, in the resin composition of the present invention, other components such as epoxy resin (bisphenol A type, novolac type, glycidyl ester type, etc.) and phosphorus-based stabilizer (phosphoric acid ester-based) are used as long as the object of the present invention is not impaired. Etc.), weather resistant agents (resorcinol type, salicylate type, benzotriazole type, benzophenone type, hindered amine type, etc.), lubricants (montanic acid and its esters, their half esters, stearyl alcohol, stearamide, various bisamides, bisurea, polyethylene wax, etc. ), Pigments (cadomium sulfide, phthalocyanine, phosphoric acid, perylene, naphthaltocyanin, quinacridone, carbon black, titanium oxide, iron oxide, azo, monoazo, etc.), dyes (azine, azo, perylene, anthraquinone, etc.) ), Crystal nucleating agent (talc, polyether ether ketone, etc.), plasticizing agent (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agent (alkylsulfate type anionic antistatic agent, quaternary ammonium Salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agents, etc., flame retardants (eg, red phosphorus, melamine cyanurate, ammonium polyphosphate, etc.) Bromineed polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin or a combination of these brominated flame retardants and antimonite trioxide, etc.), antistatic agents (phosphoric acid, phosphite, trimethyl phosphate, phosphorus, etc.) Phosphoric acid compounds such as triphenyl acid), other polymers and the like can be contained.

The method for producing the resin composition of the present invention is not particularly limited as long as the requirements specified in the present invention are satisfied, and for example, polyester resin (A), glass fiber (B), metal salt compound (C), and the like. If necessary, a method of uniformly melt-kneading the other components with a single-screw or twin-screw extruder, a method of mixing in a solution and then removing the solvent, and the like are preferably used. From the viewpoint of productivity, a method of uniformly melt-kneading with a single-screw or twin-screw extruder is preferable, and from the viewpoint of obtaining a resin composition having excellent fluidity and mechanical properties, uniform melt-kneading is performed with a twin-screw extruder. The method is more preferred. Among them, when the screw length is L and the screw diameter is D, a method of melt-kneading using a twin-screw extruder with L / D> 30 is particularly preferable. The screw length referred to here refers to the length from the position where the raw material at the base of the screw is supplied to the tip of the screw. The upper limit of the L / D of the twin-screw extruder is 150, and preferably the L / D exceeds 30 and 100 or less can be used.

Further, in the present invention, as a screw configuration when used in a twin-screw extruder, a full flight and a kneading disc are used in combination, but uniform kneading with a screw is required to obtain the composition of the present invention. be. Therefore, the ratio of the total length (kneading zone) of the kneading disc to the total length of the screw is preferably in the range of 5 to 50%, and more preferably in the range of 10 to 40%.

In the case of melt-kneading in the present invention, the method of charging each component is, for example, using an extruder having two charging ports, and polyester resin (A) and glass fiber (B) from the main charging port installed on the screw root side. ), Metal salt compound (C) and other components as needed, and polyester resin (A), metal salt compound (C) and other components are supplied from the main inlet and the main inlet and extruder. Examples thereof include a method in which the glass fiber (B) is supplied from the sub-input port installed between the tips and melt-mixed.

The resin composition of the present invention can be molded by any known method such as injection molding, extrusion molding, blow molding, press molding, spinning, etc., and can be processed and used in various molded products. The molded product can be used as an injection-molded product, an extrusion-molded product, a blow-molded product, a film, a sheet, a fiber, or the like. It can be used as various fibers such as undrawn yarn, drawn yarn, and super drawn yarn.

In the present invention, the various molded products can be used for various purposes such as automobile parts, electric / electronic parts, building parts, various containers, daily necessities, household goods and sanitary goods, and in particular, laser welding is possible. , Suitable for laser welding automobile parts and electrical / electronic parts.

The resin composition of the present invention can be used for the following specific applications. Specific examples include an air flow meter, an air pump, a thermostat housing, an engine mount, an ignition hobin, an ignition case, a clutch bobbin, a sensor housing, an idle speed control valve, a vacuum switching valve, an ECU housing, a vacuum pump case, an inhibitor switch, and a rotation sensor. Acceleration sensor, distributor cap, coil base, actuator case for ABS, radiator tank top and bottom, cooling fan, fan shroud, engine cover, cylinder head cover, oil cap, oil pan, oil filter, fuel cap, fuel strainer, distributor Underhood parts for automobiles such as turcaps, vapor canister housings, air cleaner housings, timing belt covers, brake booster parts, various cases, various tubes, various tanks, various hoses, various clips, various valves, various pipes, torque control levers. , Safety belt parts, register blades, washer levers, wind regulator handles, wind regulator handle knobs, passing light levers, sun visor brackets, automobile interior parts such as various motor housings, roof rails, fenders, garnishes, bumpers, door mirror stays, Various automobile exterior parts such as spoiler, hood louver, wheel cover, wheel cap, grill apron cover frame, lamp reflector, lamp bezel, door handle, wire harness connector, SMJ connector, PCB connector, door grommet connector, etc. Mobile terminals such as electrical connectors, relay cases, coil bobbins, optical pickup chassis, motor cases, laptop housings and internal parts, CRT display housings and internal parts, printer housings and internal parts, mobile phones, mobile PCs, handheld mobiles, etc. Housing and internal parts, recording medium (CD, DVD, PD, FDD, etc.) drive housing and internal parts, copy machine housing and internal parts, facsimile housing and internal parts, parabolic antennas and other electrical and electronic parts Can be mentioned.

Furthermore, VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave parts, audio parts, video camera parts, video equipment parts such as projectors, laser discs (registered trademarks), compact discs (CDs), CD-ROMs. , CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD-RAM, Blu-ray Disc and other optical recording media boards, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts. , And other household and office electrical product parts can be mentioned.

In addition, housings and internal parts of electronic musical instruments, home-use game machines, portable game machines, various gears, various cases, sensors, LEP lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, condensers, variable condenser cases. , Optical pickup, oscillator, various terminal boards, transformer, plug, printed wiring board, tuner, speaker, microphone, headphones, small motor, magnetic head base, power module, semiconductor, liquid crystal, FDD carriage, FDD chassis, motor brush Electrical and electronic parts such as holders, transformer members, coil bobbins, sash door rollers, blind curtain parts, piping joints, curtain liners, blind parts, gas meter parts, water meter parts, water heater parts, roof panels, heat insulating walls, adjusters, plastic bundles, Building materials such as ceiling fishing gear, stairs, doors, floors, fishing threads, fishing nets, seaweed farming nets, fishery-related parts such as fishing bait bags, vegetation nets, vegetation mats, weed-proof bags, weed-proof nets, curing sheets, slopes Protective sheet, fly ash holding sheet, drain sheet, water retention sheet, sludge / hedro dehydration bag, civil engineering related parts such as concrete mold, gears, screws, springs, bearings, levers, key stems, cams, ratchets, rollers, water supply parts, Toy parts, fans, tegusu, pipes, cleaning jigs, motor parts, microscopes, binoculars, cameras, clocks and other mechanical parts, multi-films, tunnel films, bird-proof sheets, vegetation protection non-woven fabrics, seedling raising pots, vegetation Pile, seed string tape, germination sheet, house lining sheet, agricultural vinyl stopper, slow-release fertilizer, root-proof sheet, gardening net, insect-proof net, young tree net, print laminate, fertilizer bag, sample bag, clay sac , Animal damage prevention nets, incentive strings, windbreak nets and other agricultural materials, paper diapers, sanitary goods packaging materials, cotton sticks, squeezers, toilet seat wipes and other sanitary goods, medical non-woven fabrics (sewn part reinforcement, adhesion prevention film, artificial organ repair) Materials), wound clothing, scratch tape bandages, patch base cloth, surgical sutures, fracture reinforcements, medical films such as medical films, calendars, stationery, clothing, food packaging films, trays, blister, Containers / tableware such as knives, forks, spoons, tubes, plastic cans, pouches, containers, tanks, baskets, hot fill containers, containers for microwave cooking Cosmetic containers, wraps, foam buffers, paper lami, shampoo bottles , Beverage bottles, cups, candy packaging, shrink labels, lids Materials, envelopes with windows, fruit baskets, hand-cut tapes, easy peel packaging, egg packs, HDD packaging, compost bags, recording media packaging, shopping bags, containers and packaging such as wrapping films for electrical and electronic parts, natural fibers Various clothing such as composites, polo shirts, T-shirts, inners, uniforms, sweaters, socks, ties, curtains, chairs, carpets, table cloths, futons, wallpapers, interior goods such as bags, carrier tapes, print lami, heat sensitive Stencil printing film, release film, porous film, container bag, credit card, cash card, ID card, IC card, paper, leather, hot melt binder such as non-woven fabric, magnetic material, zinc sulfide, electrode material powder, etc. Binder, optical element, conductive embossed tape, IC tray, golf tee, garbage bag, cash register bag, various nets, toothbrush, stationery, drainage net, body towel, hand towel, tea pack, drain filter, clear file, coat It is useful as an agent, adhesive, bag, chair, table, cooler box, bag, hose reel, planter, hose nozzle, dining table, desk surface, furniture panel, kitchen cabinet, pen cap, gas lighter, etc. Since the resin composition of the present invention has not only high laser permeability and laser weldability but also good mechanical properties and injection moldability, among the above, various automobile parts and electrical / electronic parts that perform laser welding are particularly effective. Especially useful for.

In laser welding applications, a molded product made of a resin composition having laser transparency and used as a laser transmitting member is required to have high laser transparency controlled at each part of the molded product. .. By having high transparency, energy can be efficiently transferred to the welding surface, so that the productivity of laser welding can be improved. The laser transmittance is expressed as, for example, a laser transmittance measured using a spectrophotometer or the like, and is calculated as a ratio of the amount of incident light to the amount of transmitted light when light of a specific wavelength is incident on a molded product. For example, in the case of a molded product having a thickness of 2 mm, the laser transmittance is preferably 20% or more, more preferably 25% or more, still more preferably 30% or more at a wavelength of 940 nm.

Further, since the laser transmittance is highly controlled at each part of the molded product, welding failure is less likely to occur, and stable laser welding property can be obtained. This can be evaluated by the stability of laser transmission. Specifically, as a variation in laser transmittance, for example, when the transmittance is measured at a plurality of different parts of a molded product, the difference between the maximum value and the minimum value of the transmittance is divided by the average value of the transmittance. It is evaluated as a variation ratio. The variation ratio is preferably 15% or less, more preferably 10% or less, still more preferably 5% or less.

Next, the present invention will be described in more detail by way of examples, but these are not limited to the present invention.

The abbreviations of the main raw materials used in the examples and their contents are summarized below.

(A) Polyester resin A-1: Polybutylene terephthalate (terminal carboxyl group concentration 50 eq / t).
A-2: Polybutylene terephthalate (terminal carboxyl group concentration 30 eq / t).
A-3: Polybutylene terephthalate (terminal carboxyl group concentration 15 eq / t).
A-4: Polybutylene terephthalate (terminal carboxyl group concentration 9 eq / t).

(B) Glass fiber B-1: Round cross section chopped strand type glass fiber (fiber diameter 13 μm, flatness 1)
B-2: Oval cross-section chopped strand type glass fiber (fiber minor axis 10 μm, fiber major axis 20 μm, flatness 2)
B-3: Chopped strand type glass fiber having an oval cross section (fiber minor axis 7 μm, fiber major axis 28 μm, flatness 4).

(C) Metal salt compound C-1: Sodium propionate (3 carbon atoms, 96 molecular weight)
C-2: Sodium caprylate (8 carbon atoms, molecular weight 166)
C-3: Sodium stearate (18 carbon atoms, molecular weight 306)
C-4: Sodium formate (carbon number 1, molecular weight 68)
C-5: Sodium polyacrylate (repeating unit has 3 carbon atoms, repeating unit has a molecular weight of 94)
C-6: Potassium stearate (18 carbon atoms, molecular weight 326)
C-7: Magnesium stearate (36 carbon atoms, molecular weight 591).

In addition, the evaluation methods used in the examples and comparative examples are summarized below.

(1) Crystallinity High-speed calorimeter measurement and crystallinity calculation were performed according to the following temperature program using a test piece cut out from a resin pellet of a polyester resin composition to an appropriate size of 100 to 500 nanograms. .. A FLASH DSC 1 manufactured by METTLER TOLEDO was used as a testing machine, and a STARe Software manufactured by METTLER TOLEDO was used for data processing. The crystallinity is expressed as a percentage of the ratio of the amount of heat of crystal melting obtained by high-speed calorymmetric measurement to the amount of heat of crystal melting of a perfect crystal. The higher the crystallinity, the better the injection moldability and laser transparency.
Temperature program:
[1] The temperature was raised from 30 ° C. to 260 ° C. at 10000 ° C./sec. [2] The temperature was maintained at 260 ° C. for 0.1 seconds. [3] The temperature was cooled to 80 ° C. at 5000 ° C./sec. It was held for 1 second, cooled to −70 ° C. at 5000 ° C./sec, and heated to 260 ° C. at 1000 ° C./sec.

(2) Average Length of Linear Structure A laser beam transmittance evaluation test piece having a square L of 80 mm and a thickness D of 2 mm shown in FIG. 1 was molded. The molding conditions are a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. The sprue 1 and runner 2 portions of the molded piece shown in FIG. 1 are cut by a gate 3, and a focused ion beam device / scanning electron microscope manufactured by SIINT Co., Ltd. is used from the inside of the test piece 1 mm in the thickness direction from the center of the test piece. Using a composite device (SMI3200SE), a microsampling system (FB-2000A) manufactured by Hitachi High-Tech, and a focused ion beam device / scanning electron microscope composite device (Strata400S) manufactured by FEI, thin sections with a thickness of 100 nanometers can be obtained. It was prepared and stained with ruthenium tetraoxide to prepare a sample. The obtained sample was observed with a high-resolution transmission electron microscope (H9000UHR) manufactured by Hitachi under the conditions of an acceleration voltage of 300 kV and a magnification of 20000. With respect to the structure, 10 arbitrarily selected length directions were measured, and the average length was calculated.

(3) Laser Beam Transparency A laser beam transmittance evaluation test piece having a square L of 80 mm and a thickness D of 2 mm shown in FIG. 1 was molded. The molding conditions are a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. The sprue 1 and runner 2 portions of the molded piece shown in FIG. 1 were cut at the gate 3, and the remaining portion 4 was used as a laser beam transmittance evaluation test piece. An ultraviolet-near-infrared spectrophotometer (UV-3150) manufactured by Shimadzu Corporation was used as the testing machine, and an integrating sphere was used as the detector. Transmittance expresses the ratio of the amount of transmitted light to the amount of incident light as a percentage. The measurement points are the three points [1] to [3] shown in FIG. 1, [1] and [3] are the portions 13 mm inward from the end of the molded piece, and [2] is the central portion of the molded product. be. In the table showing the examples and comparative examples, the average value of the light transmittance in the near infrared 940 nm wavelength region measured at three points as the laser transmittance and the transmittance represented by the following formula as the variation of the laser transmittance. The variation ratio of is described.
Variable transmittance ratio = (maximum transmittance-minimum transmittance) / average transmittance x 100.

(4) Tensile strength For ISO1A dumbbell test pieces molded at a cylinder temperature of 260 ° C and a mold temperature of 80 ° C according to ISO527-1 and ISO, a tensile tester (Autograph AG-50kNXPlus) manufactured by Shimadzu Corporation was used. , The tensile strength was measured under the condition of the test speed of 5 mm / min.

[Examples 1 to 11 and Comparative Examples 1 to 3]
The polyester resin (A), the metal salt compound (C) and other raw materials are collectively blended in the blending ratios shown in Tables 1 and 2, and the glass fiber (B) is supplied from the side feeder, and L / D = 45-2. Using a shaft extruder, melt-kneading was performed under the conditions of a cylinder temperature of 260 ° C. and a rotation speed of 250 rpm to obtain a pellet-shaped resin composition. The obtained resin composition was injection-molded with an injection molding machine SE100DU manufactured by Sumitomo Heavy Industries, Ltd. at a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. The above evaluation was performed using each evaluation molded product.

The evaluation results are shown in Tables 1 and 2. Table 1 shows examples and Table 2 shows comparative examples.

表１および２の結果より以下のことが明らかとなった。

From the results in Tables 1 and 2, the following became clear.

In Examples 1 to 11, as compared with Comparative Examples 1 to 3, the degree of crystallinity of the polyester resin composition is set to a specific value, so that the injection moldability is excellent and the high laser permeability is different in the molded product. It was possible to obtain a highly controlled polyester resin composition. Further, by containing a specific amount of the polyester resin (A), the glass fiber (B), and the metal salt compound (C), a molded product having good injection moldability and excellent laser permeability and mechanical strength can be obtained. Was made. More specifically, Examples 1 to 4 contain a metal salt compound (C) that is preferable in terms of compatibility with the polyester resin (A) as compared with Comparative Examples 2 and 3. It was possible to obtain a molded product having excellent crystal nucleation efficiency, and as a result, good injection moldability and excellent laser transmission. Further, in Example 5, since the amount of metal ions added per 1 kg of PBT is contained in a preferable range as compared with Comparative Example 1, the crystal nucleation efficiency is excellent, and as a result, the injection moldability is good and the laser is used. A molded product having excellent permeability could be obtained.

In Example 4, the terminal carboxyl group concentration of the polyester resin (A) is in a more preferable range as compared with Examples 1 to 3, so that the compatibility with the metal salt compound (C) is excellent, and as a result, the compatibility with the metal salt compound (C) is excellent. A molded product having good injection moldability and excellent laser permeability could be obtained.

Example 3 produces crystal nuclei by containing a metal salt compound (C) having a more preferable carbon number in that it is superior in compatibility with the polyester resin (A) as compared with Examples 5 and 6. As a result, it was possible to obtain a molded product having the same laser permeability and superior mechanical strength even when the amount of metal ions per 1 kg of the polyester resin (A) was small.

Example 7 contains a glass fiber (B) having a more preferable flatness than that of Examples 3 and 8, and as a result, a molded product having better laser transparency and mechanical strength can be obtained. did it.

In Example 9, as compared with Example 3, the terminal carboxyl group concentration of the polyester resin (A) is in a more preferable range, and by containing the glass fiber (B) having a more preferable flatness, the metal salt compound ( It was possible to obtain a molded product having excellent compatibility with C), and as a result, having good injection moldability and being superior in laser permeability and mechanical strength.

Since Examples 3, 5, and 6 contain a metal salt compound (C) of a more preferable metal species as compared with Examples 10 and 11, the crystal nucleation efficiency is excellent. As a result, it was possible to obtain a molded product having good injection moldability and excellent laser permeability and mechanical strength.

1. 1. Sprue 2. Runner 3. Gate 4. Laser beam transparency evaluation test piece

Claims (8)

A polyester resin composition having a crystallinity of 15% or more calculated by the following method using high-speed calorimetry.
Calculation method: Using high-speed crystallization, the polyester resin composition was heated from 30 ° C. to 260 ° C. at 10000 ° C./sec, held at 260 ° C. for 0.1 second, and then cooled to 80 ° C. at 5000 ° C./sec. Crystallinity calculated from the curve obtained when the mixture was held at 80 ° C. for 0.1 second, cooled to −70 ° C. at 5000 ° C./sec, and then heated to 260 ° C. at 1000 ° C./sec. The polyester resin composition according to claim 1, wherein the average length in the length direction of the linear structure observed using a transmission electron microscope is 150 nanometers or less. The glass fiber (B) is contained in an amount of more than 0 and 100 parts by mass or less with respect to 100 parts by mass of the polyester resin (A), and the metal salt compound (C) contains 50 to 50 metal ions with respect to 1 kg of the polyester resin (A). The polyester resin composition according to claim 1 or 2, which comprises a concentration of 150 mmol. The polyester resin composition according to claim 3, wherein the polyester resin (A) has a terminal carboxyl group concentration of 20 eq / t or less. The polyester resin composition according to claim 3 or 4, wherein the flatness of the glass fiber (B) calculated by the following formula is 1 to 2.
Flatness = major axis / minor axis of glass fiber cross section Any of claims 3 to 5, wherein the metal salt compound (C) is an aliphatic carboxylic acid sodium salt which is at least one selected from sodium propionate, sodium caprilate, sodium stearate, and a mixture thereof. The polyester resin composition according to. A molded product comprising the polyester resin composition according to any one of claims 1 to 6. A composite molded product obtained by laser welding the molded product according to claim 7.

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