Laser-weldable polybutylene terephthalate resin composition, molded article thereof, and method for improving laser transmittance

Abstract

To provide a polybutylene terephthalate resin composition exhibiting superior laser transmittance, and a molded article exhibiting superior laser transmittance, the molded article being obtained by molding the composition.SOLUTION: A laser-weldable polybutylene terephthalate resin composition comprises 15 to 91 pts.mass of (B) glass fiber relative to 100 pts.mass of (A) polybutylene terephthalate resin, the (B) glass fiber containing iron oxide in which the divalent iron oxide ratio is 80 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laser-weldable polybutylene terephthalate resin composition having excellent laser weldability, a molded article made from the same, and a method for improving laser transmittance. [Background technology]

[0002] Polybutylene terephthalate resin is widely used as an injection molded product in fields such as machine parts, electrical and communication parts, and automotive parts, taking advantage of its excellent injection moldability, mechanical properties, heat resistance, electrical properties, and chemical resistance. However, although injection molded products made from polybutylene terephthalate resin have good molding efficiency, there are limitations on the shape they can be made into due to their flow properties and mold structure, and molding overly complex parts is difficult.

[0003] For this reason, joining parts as product shapes become more complex has traditionally involved adhesive bonding or mechanical bonding using bolts, etc. However, adhesives have low adhesive strength, and mechanical bonding using bolts, etc., poses problems with cost, the effort required for fastening, and increased weight. On the other hand, external heat welding such as laser welding and hot plate welding, and frictional heat welding such as vibration welding and ultrasonic welding can join parts in a short time, and because they do not use adhesives or metal parts, they do not incur problems such as the associated cost, increased weight, and environmental pollution, and as such, assembly using these methods is becoming increasingly common.

[0004] Laser welding is a method of joining two transparent and non-transparent resin materials by overlapping them and irradiating them with a laser beam from the transparent resin side, thereby heating and melting the mating surfaces of the transparent and non-transparent resin materials. The laser beam passes through the transparent resin material and is absorbed by the non-transparent resin material, and the laser beam absorbed at the mating surface is accumulated, resulting in the non-transparent resin material being heated and melted, and the transparent resin material also melts due to heat transfer from the mating surface, joining the two together.

[0005] In particular, when used as a structural material for cases and covers that house electronic components, etc., high strength is required, so fillers such as glass fiber are added. However, adding fillers such as glass fiber reduces the transmittance of laser light, which causes the problem of reduced laser weldability.

[0006] To solve the above problems, Patent Document 1 proposes a method of improving laser transmittance by adding an amorphous resin such as a polycarbonate resin to a polybutylene terephthalate resin. Patent Document 2 proposes a method of improving laser transmittance by selecting the amount of iron oxide contained in glass fibers. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-52223 [Patent Document 2] Japanese Patent Publication No. 2020-7427 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, when polybutylene terephthalate resin is used as a structural material, high strength is required, so fillers such as glass fibers are added. However, adding fillers such as glass fibers reduces laser transmittance, adversely affecting laser weldability. In the technology described in Patent Document 1, laser transmittance is improved by adding an amorphous resin, but increasing the amount of amorphous resin added deteriorates fluidity. In the technology described in Patent Document 2, the amount of iron oxide contained in the glass fiber is mainly due to the raw material ore, but variations in the amount of iron oxide cause variations in laser transmittance, which affects laser weldability. [Means for solving the problem]

[0009] As a result of extensive research and investigation to solve the above problems, the present inventors have found that by using glass fibers containing a specific ratio of divalent iron oxide, it is possible to obtain a polybutylene terephthalate resin composition with improved laser transmittance and excellent laser weldability, and a molded article obtained by molding the same, which has led to the completion of the present invention.

[0010] That is, the present invention has the following configuration. (1) A fiber-reinforced polybutylene terephthalate resin composition for laser welding, which is obtained by blending 15 to 91 parts by mass of (B) glass fiber with 100 parts by mass of (A) polybutylene terephthalate resin, wherein the proportion of divalent iron oxide in the iron oxide contained in the (B) glass fiber is 80% by mass or less. (2) The polybutylene terephthalate resin composition for laser welding according to (1), wherein the (B) glass fiber is E-glass. (3) The polybutylene terephthalate resin composition for laser welding according to (1) or (2), further comprising 5 to 90 parts by mass of (C) polycarbonate resin blended with 100 parts by mass of (A) polybutylene terephthalate resin. (4) The polybutylene terephthalate resin composition for laser welding according to any one of (1) to (3), further comprising 1 to 25 parts by mass of (D) a styrene-based resin containing a rubber component, per 100 parts by mass of (A) the polybutylene terephthalate resin. (5) The polybutylene terephthalate resin composition for laser welding according to any one of (1) to (4), further comprising 0.05 to 5 parts by mass of (E) a crystal nucleating agent, based on 100 parts by mass of (A) the polybutylene terephthalate resin. (6) A polybutylene terephthalate resin composition for laser welding according to any one of (1) to (5), wherein a laser beam transmittance at a wavelength of 940 nm measured on a sample having a thickness of 2 mm of a molded article made of the polybutylene terephthalate resin composition is 15% or more. (7) The polybutylene terephthalate resin composition for laser welding according to any one of (1) to (6), wherein, in the relationship between the amount of iron oxide contained in the (B) glass fiber and the laser beam transmittance at a wavelength of 940 nm measured on a sample of 2 mm thick of a molded article made of the polybutylene terephthalate resin composition using the (B) glass fiber, when the content of the amount of iron oxide in the (B) glass fiber is 0.10 to 0.30 mass%, the absolute value of the slope obtained by the least squares method is 50 or less. (8) A molded article obtained by molding the laser-weldable polybutylene terephthalate resin composition according to any one of (1) to (7). (9) A method for improving the laser transmittance of a polybutylene terephthalate resin composition by blending 15 to 91 parts by mass of (B) glass fiber with 100 parts by mass of (A) polybutylene terephthalate resin, and adjusting the ratio of divalent iron oxide in the iron oxide contained in the (B) glass fiber to 80% by mass or less. (10) A method for reducing fluctuations in laser transmittance of a polybutylene terephthalate resin composition due to fluctuations in the content of iron oxide in (B) glass fiber, by blending 15 to 91 parts by mass of (B) glass fiber with 100 parts by mass of (A) polybutylene terephthalate resin and setting the ratio of divalent iron oxide in the iron oxide contained in (B) glass fiber to 80 mass% or less. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition having excellent laser transmittance, and a molded article obtained by molding the same. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a graph showing the relationship between the total amount of iron oxide contained in glass fibers and laser beam transmittance in Examples 3 to 5, 8 to 10, and Comparative Examples 3 to 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below.

[0014] <Polybutylene terephthalate resin> The polybutylene terephthalate resin (A) used in the present invention is a polymer obtained by polycondensation of terephthalic acid and / or its ester-forming derivative with 1,4-butanediol and / or its ester-forming derivative. Examples of ester-forming derivatives of terephthalic acid include alkyl esters of terephthalic acid, such as dimethyl terephthalate. Examples of ester-forming derivatives of 1,4-butanediol include alkyl esters of diols, such as 1,4-butanediol esters.

[0015] As long as the properties are not impaired, the copolymer may be one obtained by copolymerizing terephthalic acid or its ester-forming derivative with another dicarboxylic acid or its ester-forming derivative, or one obtained by copolymerizing 1,4-butanediol or its ester-forming derivative with another diol or its ester-forming derivative. Examples of dicarboxylic acids or their ester-forming derivatives used as copolymerization components include isophthalic acid, adipic acid, oxalic acid, sebacic acid, decanedicarboxylic acid, naphthalenedicarboxylic acid, and alkyl esters thereof. Two or more of these may be used. Examples of diols or their ester-forming derivatives used as copolymerization components include ethylene glycol, propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, long-chain glycols such as polyethylene glycol, poly-1,3-propylene glycol, and polytetramethylene glycol having a molecular weight of 400 to 6000, and fatty acid esters thereof. Two or more of these may be used. These copolymerization components preferably account for 20% by mass or less of the raw materials forming (A) polybutylene terephthalate.

[0016] Preferred examples of such copolymers include polybutylene (terephthalate / isophthalate), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene (terephthalate / naphthalate), poly(butylene / ethylene) terephthalate, etc. Two or more of these may be blended.

[0017] The method for producing the polybutylene terephthalate resin (A) used in the present invention is not particularly limited, and known polycondensation methods, ring-opening polymerization methods, etc. Either a batch polymerization method or a continuous polymerization method may be used, and either a method involving a transesterification reaction and a polycondensation reaction, or a method involving a polycondensation reaction by direct polymerization (direct polymerization method) may be applied.

[0018] The polybutylene terephthalate (A) used in one example of the present invention preferably has a melt flow rate (hereinafter sometimes abbreviated as "MFR") in the range of 5 to 80 g / 10 min under conditions of 250°C and 1000 gf. If the MFR is 5 g / 10 min or more, the flowability can be further improved. 30 g / 10 min or more is more preferable. On the other hand, if the MFR is 80 g / 10 min or less, a molded product with excellent mechanical properties can be obtained. 70 g / 10 min or less is more preferable. In this specification, the MFR is a value measured in accordance with ISO1133:2011.

[0019] In one example of the present invention, the carboxyl group content of the polybutylene terephthalate resin (A) used is preferably 30 eq / t or less, more preferably 20 eq / t or less, and most preferably 15 eq / t or less, from the viewpoint of hydrolysis resistance. The lower limit of the carboxyl group concentration is 0 eq / t. Here, the carboxyl group content of the polybutylene terephthalate resin (A) is a value measured by dissolving the polybutylene terephthalate resin (A) in an o-cresol / chloroform solvent and then titrating with ethanolic potassium hydroxide.

[0020] <Glass fiber> The polybutylene terephthalate resin composition of the present invention contains (B) glass fibers. The (B) glass fibers are preferably E-glass. The average fiber diameter of the glass fibers is preferably 15 μm or less, and more preferably 13 μm or less. The aspect ratio (average fiber length / average fiber diameter) of the (B) glass fibers used in the present invention is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. The (B) glass fibers may be coated or bundled with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin, or may be treated with a coupling agent such as aminosilane or epoxysilane.

[0021] The blending amount of (B) glass fiber used in the present invention is 15 to 91 parts by mass relative to 100 parts by mass of (A) polybutylene terephthalate resin composition. A blending amount less than 15 parts by mass is undesirable because the material strength is low. A blending amount exceeding 91 parts by mass is undesirable for laser welding applications because the laser transmittance is reduced.

[0022] The total mass of iron oxide contained in the (B) glass fiber used in the present invention is preferably 0.25 mass% or less, and more preferably 0.24 mass% or less. An iron oxide amount exceeding 0.25 mass% is undesirable because it reduces laser transmittance. The iron oxide amount in the present invention is expressed as an Fe2O3 equivalent amount, and is a value determined by fluorescent X-ray analysis in accordance with JIS R3420:2013.

[0023] The divalent iron oxide ratio of the iron oxide contained in the (B) glass fiber used in the present invention is 80% by mass or less. (Here, the divalent iron oxide ratio refers to the percentage of the amount of divalent iron oxide relative to the total mass of iron oxide.) It is more preferably 60% by mass or less, and most preferably 50% by mass or less. If the divalent iron oxide ratio exceeds 80% by mass, the laser transmittance decreases and the laser weldability deteriorates. Furthermore, if the amount of iron oxide contained in the glass fiber varies, the laser transmittance also varies, which undesirably affects the weldability during laser welding and reduces production efficiency. The lower the divalent iron oxide ratio, the better from the perspective of laser transmittance, so there is no substantial lower limit, and 0% by mass is most preferable, but from the perspective of availability, it is preferably 10% by mass or more.

[0024] By using the above glass fiber, it is possible to improve laser transmittance and reduce fluctuations in laser transmittance due to variations in the total mass of iron oxide. The above divalent iron oxide ratio is determined during the process of manufacturing the glass fiber. Iron oxide exists as a mixture of divalent and trivalent iron oxides, and this ratio is thought to be determined by the amount of heat and additives such as oxidizers during the glass fiber manufacturing process, and is thought not to vary significantly unless there is a change in the manufacturing process. Therefore, even if there is a variation in the total mass of iron oxide contained in the glass fiber, as long as the divalent iron oxide ratio is equal to or less than the above ratio, fluctuations in laser beam transmittance due to variations in the total mass of iron oxide are reduced.

[0025] The divalent iron oxide ratio is measured by X-ray absorption fine structure spectroscopy (XAFS), which involves irradiating glass fibers with X-rays and measuring the amount of X-rays absorbed.

[0026] In the XAFS spectrum, the structure near the absorption edge is called XANES (X-ray Absorption Near Edge Structure), and the extended X-ray absorption fine structure that appears approximately 100 eV or more higher energy than the absorption edge is called EXAFS (Extended X-ray Absorption Fine Structure). Information about the valence and structure of the target atom can be obtained from XANES, and in EXAFS analysis, information about the local structure of the sample, the atomic species, valence, and distance around the target atom can be obtained by Fourier transform of the actual spectrum (equivalent to FT-EXAFS / radial distribution function).

[0027] The ratio of divalent iron oxide contained in the glass fiber was measured from the rising region of the Fe K-edge XANES of the Fe standard sample and each glass fiber sample. The measurement procedure was as follows.

[0028] As a preliminary step, the energy axis is calibrated so that the peak in the pre-edge region of the Cu metal foil is 8981.3 eV in the Cu K-edge XAFS.

[0029] A 1g glass fiber sample was sealed in a polyethylene bag and positioned so that the fiber orientation was perpendicular to the instrument installation surface and the sample surface was perpendicular to the X-ray irradiation direction. The X-ray beam irradiation area was 0.3mm x 0.4mm, and the size and shape of the elliptical X-rays were 0.1mm x 0.2mm. Multiple glass fibers were tightly arranged in an area approximately 1cm square, ensuring that all X-rays irradiated the sample. The sample surface on which the glass fibers were arranged was oriented at a 45° angle to the X-ray irradiation direction, and a silicon drift detector (fluorescence yield detector) was positioned at a 90° angle to the X-ray irradiation direction. To minimize energy deviations during glass fiber evaluation, the X-rays transmitted through the glass fiber were simultaneously measured for Fe metal, a reference sample, using ion chambers (I1 and I2) downstream of the glass fiber sample to perform energy axis correction of the sample measurement data.

[0030] The data of the sample of interest obtained as described above is normalized using the XAFS analysis software athena so that, with E0 (7112.1 eV) as the reference, the average intensity in the region before the absorption edge from -150 eV to -30 eV is 0, and the average intensity in the region after the absorption edge from +150 to +900 eV is 1, and the energy at which the intensity becomes 0.5 in the XANES region is read. In addition, the energies are similarly read for FeO, a standard sample of divalent iron oxide, and Fe2O3, a standard sample of trivalent iron oxide, which were separately measured by the transmission method, and the divalent iron oxide ratio of the glass fiber sample is calculated from the calibration curve created using the standard sample data.

[0031] The measurement conditions are as follows. Experimental facility: Aichi Synchrotron Light Center, Experimental station: BL11S2, Spectrometer: Si(111)2 crystal spectrometer, Absorption edge: Fe K absorption edge (7112 eV), Detection method: Fluorescence yield method, Detector: Silicon drift detector.

[0032] The laser beam transmittance of a molded article obtained from the resin composition of the present invention is plotted against the total mass of iron oxide contained in the glass fiber used, and the slope of the relationship between laser beam transmittance and the total mass of iron oxide is determined by the least squares method. The lower the absolute value of the slope, the less fluctuation in laser beam transmittance due to fluctuations in the total mass of iron oxide, and this is preferable. An absolute value of the slope of 50 or less is good, 30 or less is very good, and 15 or less is most preferable. There is no lower limit to the slope, but it is essentially 1 or greater.

[0033] <Polycarbonate resin> Furthermore, the resin composition used in the present invention may contain (C) a polycarbonate resin.

[0034] Polycarbonate resins are polymers obtained by reacting a dihydric phenol with a carbonate precursor such as phosgene or a carbonate ester compound. For example, they are produced by reacting a dihydric phenol with a carbonate precursor such as phosgene in a solvent such as methylene chloride, or by transesterification of a dihydric phenol with a carbonate precursor such as diphenyl carbonate. There are various dihydric phenols, but 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) is particularly preferred. Examples of dihydric phenols other than bisphenol A include bis(4-hydroxyphenyl)alkanes, 1,1-(4-hydroxyphenyl)methane, 1,1-(4-hydroxyphenyl)ethane, hydroquinone, bis(4-hydroxyphenyl)cycloalkanes, bis(4-hydroxyphenyl)oxides, bis(4-hydroxyphenyl)sulfides, bis(4-hydroxyphenyl)sulfones, bis(4-hydroxyphenyl)sulfoxides, and bis(4-hydroxyphenyl)ethers. These dihydric phenols may be used alone or in combination of two or more. Examples of the carbonate ester compound include diaryl carbonates such as diphenyl carbonate, and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate.

[0035] The melt viscosity of the polycarbonate resin (C) used in the present invention may be appropriately selected and determined, but the melt volume rate (hereinafter sometimes abbreviated as MVR) measured at 300°C and 1.2 kgf is 5.0 to 30.0 cm 3 / 10 minutes range is preferable. MVR is 30.0 cm 3 On the other hand, when the melt viscosity is 5.0 cm / 10 min or less, the mechanical properties are further improved. 3 When the time is 10 minutes or more, the fluidity is further improved. 3 / 10 minutes. Two or more polycarbonate resins with different viscosities may be mixed, and polycarbonate resins with melt viscosities outside the above range may also be mixed. Polycarbonate resins with such melt viscosities are available, for example, from Mitsubishi Engineering-Plastics Corporation under the trade name "Iupilon" (registered trademark).

[0036] When (C) polycarbonate resin is blended in the present invention, the blending amount is preferably 5 to 90 parts by mass relative to 100 parts by mass of (A) polybutylene terephthalate resin. A blending amount of 5 parts by mass or more can improve laser transmittance, which is preferable. A blending amount of 90 parts by mass or less can maintain mechanical properties, which is preferable for laser welding applications. A more preferable blending amount is 10 to 80 parts by mass, and most preferably 20 to 60 parts by mass.

[0037] The polycarbonate resin (C) used in the present invention may be a recycled material that has been subjected to a recycling process such as a crushing process or a remelting process.

[0038] Although recycled polycarbonate is not particularly specified, a lower Fe ion concentration is preferable from the viewpoint of laser transparency. The preferred Fe ion concentration is 500 ppm or less, and 100 ppm or less is even more preferable. The Fe ion concentration of polycarbonate resin was measured by dissolving it in nitric acid and sulfuric acid, filtering it, and then measuring the filtrate with an atomic absorption spectrophotometer.

[0039] <Styrene-based resin containing rubber component> Furthermore, the resin composition used in the present invention can be blended with a styrene-based resin containing a rubber component (D). Blending a styrene-based resin containing a rubber component (D) can improve the thermal shock resistance and hydrolysis resistance of polybutylene terephthalate resin and molded articles thereof. Commonly used olefin-based elastomers are undesirable from the standpoint of laser transmittance; it is preferable to use a styrene-based resin containing a rubber component that has high light transmittance in the 400 to 1100 nm wavelength range. Examples of styrene-based resins containing a rubber component (D) include block copolymers of a styrene-based component and a rubber component, and those obtained by graft-polymerizing a styrene-based component onto a rubber component. Examples of rubber components include conjugated diene rubbers such as polybutadiene, styrene-butadiene copolymers, and hydrogenated styrene-butadiene block copolymers, as well as non-conjugated diene rubbers such as ethylene-propylene copolymers. Examples of styrene-based components include styrene, methylstyrene, and styrene-acrylonitrile. Such graft polymers are generally referred to as HIPS or ABS. These may be used alone or in combination of two or more.

[0040] Among the styrene-based resins containing a rubber component (D), styrene-butadiene block copolymers are preferred from the viewpoints of resistance to cold and heat shock and hydrolysis resistance.Furthermore, from the viewpoint of hydrolysis resistance, a styrene-butadiene block copolymer having an epoxy group or a combination of a styrene-butadiene block copolymer not having an epoxy group and an epoxy group-containing styrene-based resin (G) is preferred.

[0041] When a styrene-based resin containing a rubber component (D) is blended in the present invention, the blending amount is preferably 1 to 25 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin composition (A). A blending amount of 1 part by mass or more is preferred because it provides resistance to thermal shock. A blending amount of 25 parts by mass or less maintains mechanical properties, which is preferred for laser welding applications. A more preferred blending amount is 3 to 20 parts by mass, and most preferably 4 to 15 parts by mass.

[0042] <Nucleating agent> The resin composition of the present invention may contain a nucleating agent (E). The nucleating agent (E) used in the present invention may be either an inorganic nucleating agent or an organic nucleating agent. Examples of inorganic nucleating agents include synthetic mica, talc, clay, zeolite, magnesium oxide, calcium sulfide, boron nitride, and neodymium oxide. These nucleating agents are preferably modified with an organic substance to enhance dispersibility in the composition. Examples of organic crystal nucleating agents include sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, metal salts of organic carboxylic acids such as sodium β-naphthalate and sodium cyclohexanecarboxylate, organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate, sorbitol compounds, metal salts of phenylphosphonate, and metal salts of phosphorus compounds such as sodium-2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate. Among these, talc is preferred. The inclusion of these (E) crystal nucleating agents allows for stable laser transmittance of molded articles and the production of polybutylene terephthalate resin compositions and molded articles with excellent mechanical properties and moldability. Furthermore, by incorporating the (E) crystal nucleating agent, the fluctuation in laser transmittance due to the fluctuation in the amount of iron oxide contained in the (B) glass fiber is reduced, which is preferable.

[0043] In the present invention, the blending amount of (E) the crystal nucleating agent is preferably in the range of 0.05 to 5 parts by mass relative to 100 parts by mass of (A) the polybutylene terephthalate resin composition, and more preferably in the range of 0.05 to 1 part by mass from the viewpoints of moldability and laser transmittance.

[0044] <Other additives> In the present invention, a (F) phosphorus-based stabilizer may also be added. When a (C) polycarbonate resin is added, the (F) phosphorus-based stabilizer inhibits the transesterification reaction between the polybutylene terephthalate resin and the polycarbonate resin, thereby improving moist heat resistance and retention stability. Examples of the (F) phosphorus-based stabilizer include phosphate-based stabilizers (phosphate compounds) and phosphite-based stabilizers (phosphite compounds). Two or more of these may be used. Among these, phosphate-based stabilizers are preferred because they are more effective in improving the retention stability of the thermoplastic resin composition. For example, a phosphate-based stabilizer is available under the trade name "ADK STAB" (registered trademark) AX-71 manufactured by ADEKA Corporation.

[0045] In the present invention, when a styrene-butadiene block copolymer having no epoxy groups is used as the styrene-based resin containing a rubber component (D), it is preferable to use it in combination with an epoxy group-containing styrene-based resin (G). The use of the epoxy group-containing styrene-based resin (G) improves the hydrolysis resistance of the resin composition. Examples of epoxy group-containing styrene-based resins include acrylonitrile-styrene-glycidyl methacrylate (GMA) copolymers, styrene-(meth)acrylic-GMA copolymers, and ethylene-GMA-g-styrene graft copolymers. The styrene-(meth)acrylic-GMA copolymer is preferred and is available from Toagosei Co., Ltd. under the trade name "ARUFON" (registered trademark). The epoxy group-containing styrene-based resin (G) does not contain a rubber component. When the epoxy group-containing styrene-based resin (G) is added, its amount is 0.1 to 10 parts by mass per 100 parts by mass of the polybutylene terephthalate resin composition (A).

[0046] In the present invention, (H) epoxy compounds (such as bisphenol A type, novolac type, and glycidyl ester type) may be added as long as the object of the present invention is not impaired. The addition of a (H) epoxy compound can improve hydrolysis resistance. When a (H) epoxy compound is added, the compounding amount is preferably 0.1 to 5 parts by mass per 100 parts by mass of the (A) polybutylene terephthalate resin composition. By adding 0.1 part by mass or more, hydrolysis resistance can be improved, and by adding 5 parts by mass or less, the fluidity of the resin composition can be maintained. Among the (H) epoxy compounds, compounds that also fall under the category of styrene-based resins containing a rubber component are treated as (D) styrene-based resins containing a rubber component. Among the (H) epoxy compounds, styrene-based resins that do not contain a rubber component are treated as (G) epoxy group-containing styrene-based resins.

[0047] Furthermore, the resin composition of the present invention may contain other components, such as weathering agents (resorcinol-based, salicylate-based, benzotriazole-based, benzophenone-based, hindered amine-based, etc.), lubricants (montanic acid and its metal salts, its esters, its half esters, stearyl alcohol, stearamide, various bisamides, bisurea, polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine, rylene, perylene, naphthocyanine, quinacridone, carbon black, titanium oxide, iron oxide, azo-based, monoazo-based, metal complex salts, etc.), dyes (azine-based, azo-based , perylene, anthraquinone, etc.), antistatic agents (alkyl sulfate-type anionic antistatic agents, quaternary ammonium salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine-type amphoteric antistatic agents, etc.), flame retardants (for example, red phosphorus, melamine cyanurate, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.), color inhibitors (hypophosphites, etc.), other polymers, etc.

[0048] The method for producing the resin composition of the present invention is not particularly limited as long as it satisfies the requirements of the present invention. However, from the viewpoint of productivity, a method of uniformly melt-kneading using a single-screw or twin-screw extruder is preferred, and a method of uniformly melt-kneading using a twin-screw extruder is more preferred because it produces a resin composition with excellent fluidity and mechanical properties. Among these, a method of melt-kneading using a twin-screw extruder with an L / D ratio of >30, where L (mm) is the screw length and D (mm) is the screw diameter, is particularly preferred. The screw length here refers to the length from the base of the screw where the raw materials are supplied to the tip of the screw. The upper limit of the L / D ratio of the twin-screw extruder is preferably 150, and preferably an L / D ratio of more than 30 but not more than 100 is more preferred.

[0049] In the present invention, the screw configuration of a twin-screw extruder is a combination of full flight and kneading discs, and uniform kneading by the screws is necessary to obtain the composition of the present invention. Therefore, the ratio of the total length of the kneading discs (kneading zone) to the total length of the screws is preferably in the range of 5 to 50%, more preferably in the range of 10 to 40%.

[0050] In the present invention, when melt-kneading, the various components can be added by, for example, using an extruder having two inlets and feeding (A) polybutylene terephthalate resin and, if necessary, other components through a main inlet located at the base of the screw, or by feeding (A) polybutylene terephthalate resin and other components through the main inlet and feeding (B) glass fiber through a secondary inlet located between the main inlet and the tip of the extruder, followed by melt-mixing.

[0051] The resin composition of the present invention can be molded by any conventional method such as injection molding, extrusion molding, blow molding, press molding, spinning, etc., and can be processed into various molded articles for use. The molded articles can be used as injection molded articles, extrusion molded articles, blow molded articles, films, sheets, fibers, etc. The films can be used as various films such as unstretched, uniaxially stretched, and biaxially stretched films, and the fibers can be used as various fibers such as unstretched yarns, stretched yarns, and ultra-stretched yarns.

[0052] In the present invention, the above-mentioned various molded articles can be used for various purposes such as automobile parts, electrical and electronic parts, building materials, various containers, daily necessities, household goods, and sanitary products, and since they can be laser welded in particular, they are suitable as automobile parts and electrical and electronic parts that are to be laser welded.

[0053] A molded article made from the resin composition of the present invention has a laser transmittance of 15% or more at a wavelength of 940 nm, measured with a sample thickness of 2 mm. A molded article made from the resin composition with a transmittance of 15% or more can obtain sufficient welding strength when laser welded. The laser transmittance is more preferably 18% or more, and most preferably 20% or more. In the present invention, the laser beam transmittance is a value measured using an ultraviolet / near-infrared spectrophotometer and an integrating sphere as a detector.

[0054] The resin composition of the present invention can be used in the following specific applications: sensing parts such as millimeter-wave radar and camera housings, air flow meters, air pumps, thermostat housings, engine mounts, ignition hubpins, ignition cases, clutch bobbins, sensor housings, idle speed control valves, vacuum switching valves, ECU covers and housings, vacuum pump cases, inhibitor switches, rotation sensors, acceleration sensors, distributor caps, coil bases, ABS actuator cases, radiator tank tops and bottoms, cooling fans, fan shrouds, engine covers, cylinder head covers, oil caps, oil pans, oil filters, fuel caps, fuel strainers, distributor caps, 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, and other automotive underhood parts, torque control levers, and safety belt parts. , register blades, washer levers, window regulator handles, window regulator handle knobs, passing light levers, sun visor brackets, various motor housings and other automotive interior parts, roof rails, fenders, garnishes, bumpers, door mirror stays, spoilers, hood louvers, wheel covers, hubcaps, grill apron cover frames, lamp reflectors, lamp bezels, door handles and other automotive exterior parts, wire harness connectors, SMJ connectors, PCB connectors, door grommet connectors and other automotive connectors, electrical connectors, relay cases, coil bobbins, optical pickup chassis, motor cases, laptop computer housings and internal parts, CRT display housings and internal parts, printer housings and internal parts, mobile terminal housings and internal parts for mobile phones, mobile PCs, handheld mobiles and other devices, recording medium (CD, DVD, PD, FDD, etc.) drive housings and internal parts, copier housings and internal parts,Examples include electrical and electronic components such as the housing and internal parts of facsimiles, and parabolic antennas.

[0055] Further examples include parts for home and office electrical appliances such as VTR parts, television parts, irons, hair dryers, rice cooker parts, microwave oven parts, audio parts, video camera, projector and other visual equipment parts, substrates for optical recording media such as laser discs (registered trademark), compact discs (CD), CD-ROMs, CD-Rs, CD-RWs, DVD-ROMs, DVD-Rs, DVD-RWs, DVD-RAMs and Blu-ray discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, etc.

[0056] We also manufacture housings and internal parts for electronic musical instruments, home game consoles, and portable game consoles, as well as various gears, cases, sensors, LEP lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, motor brush holders, transformer components, and coil bobbins. Electrical and electronic parts, sash door rollers, blind curtain parts, piping joints, curtain liners, blind parts, gas meter parts, water meter parts, water heater parts, roof panels, insulated walls, adjusters, plastic beams, ceiling fishing tackle, stairs, doors, floors and other building materials, fishing lines, fishing nets, seaweed farming nets, fishing bait bags and other fishery-related materials, vegetation nets, vegetation mats, weed control bags, weed control nets, protective sheets, slope protection sheets, fly ash holding sheets, drain sheets, water-retaining sheets, sludge and sludge dewatering bags, concrete formwork and other civil engineering materials, gears, screws, springs, bearings, levers , key stems, cams, ratchets, rollers, water supply parts, toy parts, fans, fishing line, pipes, cleaning tools, motor parts, microscopes, binoculars, cameras, clocks and other machine parts, mulch film, tunnel film, bird repellent sheets, nonwoven fabric for vegetation protection, seedling pots, vegetation stakes, seed string tape, germination sheets, greenhouse lining sheets, agricultural plastic fasteners, slow-release fertilizers, root barrier sheets, gardening nets, insect nets, young tree nets, print laminates, fertilizer bags, sample bags, sandbags, animal damage prevention nets, attractant strings, windbreak nets and other agricultural components, disposable diapers, sanitary product packaging, cotton swabs, wet towels, toilet seat wipes Hygiene products such as medical nonwoven fabrics (suture reinforcement materials, anti-adhesion membranes, prosthetic organ repair materials), wound dressing materials, wound tape bandages, adhesive tape base fabrics, surgical sutures, fracture reinforcement materials, medical films and other medical supplies, calendars, stationery, clothing, food packaging films, trays, blisters, knives, forks, spoons, tubes, plastic cans, pouches, containers, tanks, baskets and other containers and tableware, hot fill containers, microwave cooking containers, cosmetic containers, plastic wrap, foam cushioning agents, paper laminates, shampoo bottles, beverage bottles, cups, candy packaging, shrink labels,Lid materials, window envelopes, fruit baskets, hand-tearable tape, easy-peel packaging, egg cartons, HDD packaging, compost bags, recording media packaging, shopping bags, containers and packaging such as wrapping film for electrical and electronic components, natural fiber composites, various clothing such as polo shirts, T-shirts, underwear, uniforms, sweaters, socks, and ties, interior goods such as curtains, chair upholstery, carpets, tablecloths, bedding, wallpaper, and furoshiki cloths, carrier tape, print lamination, thermal stencil printing film, release film, porous film, container bags, credit cards, cash The resin composition of the present invention is useful as a hot melt binder for cards, ID cards, IC cards, paper, leather, nonwoven fabrics, etc.; a binder for powders such as magnetic materials, zinc sulfide, and electrode materials; optical elements, conductive embossed tape, IC trays, golf tees, garbage bags, shopping bags, various nets, toothbrushes, stationery, draining nets, body towels, hand towels, tea bags, drain filters, clear files, coating agents, adhesives, bags, chairs, tables, cooler boxes, rakes, hose reels, planters, hose nozzles, dining tables, desk surfaces, furniture panels, kitchen cabinets, pen caps, gas lighters, etc. The resin composition of the present invention not only has high laser transmittance and laser weldability, but also good mechanical properties and heat cycle resistance, making it particularly useful for various automotive parts and electrical / electronic parts that are laser welded.

[0057] The polybutylene terephthalate resin composition for laser welding of the present invention is useful as a transmissive resin material that transmits laser light in laser welding. Molded articles made of the polybutylene terephthalate resin for laser welding of the present invention have improved laser transmittance, which increases production efficiency and improves laser weldability.

[0058] Furthermore, the polybutylene terephthalate resin composition for laser welding of the present invention reduces variations in laser transmittance that occur due to fluctuations in the amount of iron oxide contained in the glass fiber, thereby suppressing poor welding and scorching during laser welding that are caused by variations in laser transmittance, thereby improving production efficiency.

[0059] The laser-absorbing resin material to be laser-welded to the laser-weldable polybutylene terephthalate resin of the present invention is preferably a polybutylene terephthalate resin, which preferably contains a laser-absorbing component such as carbon black from the viewpoint of laser absorption. In this case, the carbon black content is 0.01 to 1 mass % of the total amount of the laser-absorbing resin material.

[0060] Furthermore, by adding a laser-absorbing component such as carbon black to the polybutylene terephthalate resin composition for laser welding of the present invention, it can also be used as an absorptive resin material that absorbs laser in laser welding. [Example]

[0061] Next, the present invention will be described in more detail with reference to examples, but these are not intended to limit the present invention and various modifications can be made.

[0062] (A) Polybutylene terephthalate resin A-1: Polybutylene terephthalate resin (carboxyl group content: 15 eq / t, MFR: 35 g / 10 min (250°C, 1000 gf)).

[0063] (B) Glass fiber B-1: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.24 mass%, divalent iron oxide ratio 44 mass%). B-2: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.22 mass%, divalent iron oxide ratio 44 mass%). B-3: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.20 mass%, divalent iron oxide ratio 44 mass%). B-4: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.24 mass%, divalent iron oxide ratio 52 mass%). B'-1: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.24 mass%, divalent iron oxide ratio 91 mass%). B'-2: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.22 mass%, divalent iron oxide ratio 91 mass%). B'-3: Chopped strand type glass fiber (E glass, fiber diameter 13 μm, fiber length 3.0 mm, iron oxide content 0.20 mass%, divalent iron oxide ratio 91 mass%).

[0064] (C): Polycarbonate resin C-1: Polycarbonate resin (Mitsubishi Engineering Plastics Corporation, "Iupilon" (registered trademark) H-2000, MVR: 20 cm 3 / 10 minutes (300℃ / 1.2kgf), Fe ion concentration: 52ppm. C-2: Recycled polycarbonate resin (Sun Sang Chemicals Processing Co., Ltd. PC110-BL-M, MVR: 6 cm) 3 / 10 minutes (300℃ / 1.2kgf), Fe ion concentration: 50ppm. C-3: Recycled polycarbonate resin (PC2010ANC, manufactured by Shanghai Ausell Material Technology Co., Ltd., MVR: 14 cm) 3 / 10 minutes (300℃ / 1.2kgf), Fe ion concentration: 22ppm.

[0065] (D) Styrene-based resin containing rubber components D-1: Styrene-butadiene block copolymer (manufactured by Daicel Corporation, "Epofriend" (registered trademark) AT501). D-2: Styrene-butadiene block copolymer (Tufprene (registered trademark) 125, manufactured by Asahi Kasei Corporation). D-3: ABS resin (Toyolac (registered trademark) HR2600PX02 manufactured by Toray Industries, Inc.).

[0066] (E) Nucleating Agent E-1: Hydrated magnesium silicate (talc) (Hitron manufactured by Takehara Chemical Industry Co., Ltd.).

[0067] (Other additives) (F) Phosphorus stabilizer F-1: Phosphate stabilizer (approximately equimolar mixture of mono- and di-stearyl acid phosphate) (ADEKA "ADEKA STAB" (registered trademark) AX-71).

[0068] (G) Epoxy group-containing styrene resin G-1: A copolymer obtained by copolymerizing acrylonitrile, styrene, and GMA (a bead-shaped vinyl copolymer was prepared by suspension polymerization of acrylonitrile, styrene, and GMA. The mass ratio of the acrylonitrile / styrene / GMA components was 25.5 / 74 / 0.5). G-2: Acrylic polymer having an epoxy group ("ARUFON" (registered trademark) UG-4070, manufactured by Toagosei Co., Ltd.).

[0069] (H) Epoxy compounds H-1: Dicyclopentadiene novolac epoxy compound (HP-7200H manufactured by DIC Corporation).

[0070] According to the blending compositions shown in Tables 1 to 3, (A) polybutylene terephthalate resin and all other components were fed into the bottom charging section (main inlet) of a twin-screw extruder, and (B) glass fiber was fed into a side inlet installed between the main inlet and the tip of the extruder, and melt-kneading was carried out in a twin-screw extruder (TEM37SS (trade name) manufactured by Shibaura Machine Co., Ltd.) with a screw diameter of 37 mm and an L / D of 41, and the cylinder temperature was set to 260°C. The strand discharged from the die was cooled in a cooling bath and then pelletized with a strand cutter to obtain a polybutylene terephthalate resin composition.

[0071] The evaluation methods used in the examples and comparative examples are summarized below.

[0072] (1) Laser light transmittance The polybutylene terephthalate resin composition pellets obtained in each example and comparative example were dried for 3 hours in a hot air dryer at 130°C. Then, using a SE100DU injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., a square plate test piece (80 mm x 80 mm x 2 mm thick) was molded at a cylinder temperature of 260°C and a mold temperature of 80°C. The side opposite the gate was then cut to prepare a square plate test piece (80 mm x 65 mm x 2 mm thick) for evaluating laser beam transmittance. The tester used was a Shimadzu Corporation UV-3150 ultraviolet / near-infrared spectrophotometer, and an integrating sphere was used as the detector. Transmittance is expressed as the ratio of the amount of transmitted light to the amount of incident light, expressed as a percentage. The tables showing the examples and comparative examples list light transmittance in the near-infrared 940 nm wavelength region. The obtained laser beam transmittance was plotted against the total mass of iron oxide contained in the glass fiber used, and the slope of the relationship between laser beam transmittance and the amount of iron oxide was determined by the least squares method. The lower the absolute value of the slope, the less fluctuation in laser beam transmittance due to fluctuations in the amount of iron oxide was, and this is preferable. An absolute value of the slope of 50 or less was considered good, and an absolute value of 30 or less was considered very good.

[0073] (2) Thermal shock resistance An S35C iron core measuring 47 mm in length, 47 mm in width, and 27 mm in height was placed in an insert molding die. Next, polybutylene terephthalate resin compositions according to Examples 1 to 15 and Comparative Examples 1 to 5 were injection molded into the die using a SE50DUZ injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., to obtain insert-molded articles coated with a resin thickness of 1.5 mm. The injection conditions were a cylinder temperature of 260°C, a mold temperature of 80°C, an injection pressure of 100 MPa, an injection time of 10 seconds, and a cooling time of 10 seconds. The insert-molded articles were subjected to a thermal shock chamber test using an Espec Corporation THERMAL SHOCK CHAMBER TSA-73ES, with one cycle consisting of one hour at -40°C and one hour at 130°C, and the number of cycles required for cracking to occur was measured. The presence or absence of cracking was checked every five cycles. If the number of cycles at which cracks appear is 20 or more, the insert-molded product is judged to have good thermal shock resistance, with 30 or more being more preferable.

[0074] (3) Hydrolysis resistance The pellets obtained in each example and comparative example were dried for 3 hours in a hot air dryer at 130°C, and then injection molded using a Sumitomo Heavy Industries, Ltd. SE50DUZ injection molding machine at a cylinder temperature of 260°C and a mold temperature of 80°C to produce multipurpose test specimens (type A, total length 150 mm, test section width 10 mm, thickness 4 mm) specified in ISO 3167:2002. The obtained multipurpose test specimens (type A) were subjected to hydrolysis treatment at 121°C and 100% RH for 100 hours using a HAST CHAMBER EHS-211M manufactured by Tabai ESPEC Co., Ltd. The tensile strength of the hydrolyzed test specimens was measured according to ISO 527-1,2:2012, and the tensile strength of the test specimens before and after treatment was also measured in the same manner.

[0075] The tensile strength retention rate was calculated using the following formula to evaluate hydrolysis resistance. Tensile strength retention rate (%) = (tensile strength (after hydrolysis treatment) (MPa) / tensile strength (before hydrolysis treatment) (MPa)) x 100 The hydrolysis resistance of the molded product was judged to be good if the tensile strength retention rate was 50% or more, even better if the tensile strength retention rate was 60% or more, and very good if the tensile strength retention rate was 70% or more.

[0076] The evaluation results are shown in Tables 1 to 3. Tables 1 and 2 show examples, and Table 3 shows comparative examples.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] The results in Tables 1 to 3 reveal the following.

[0081] In comparing Examples 1 to 15 with Comparative Examples 1 to 5, it was found that when the ratio of divalent iron oxide contained in the glass fiber was 80 mass% or less, the laser transmittance was improved and the fluctuation in laser transmittance relative to the fluctuation in the amount of iron oxide was reduced.

[0082] The relationship between laser beam transmittance and iron oxide amount for Examples 3 to 5, 8 to 10, and Comparative Examples 3 to 5 was plotted, and the straight line obtained by the least squares method is shown in Figure 1. The absolute value of the slope of the straight line obtained by the least squares method for the relationship between laser beam transmittance and iron oxide amount for Examples 3 to 5 was 10. The absolute value of the slope for the relationship between laser beam transmittance and iron oxide amount for Examples 8 to 10 was 8. In contrast, the absolute value of the slope for the relationship between laser beam transmittance and iron oxide amount for Comparative Examples 3 to 5 was 80.

Claims

1. A fiber-reinforced polybutylene terephthalate resin composition for laser welding, which is obtained by blending 15 to 91 parts by mass of (B) glass fiber with 100 parts by mass of (A) polybutylene terephthalate resin, wherein the proportion of divalent iron oxide in the iron oxide contained in the (B) glass fiber is 80% by mass or less.

2. 2. The laser welding polybutylene terephthalate resin composition according to claim 1, wherein the glass fiber (B) is E-glass.

3. 3. The laser welding polybutylene terephthalate resin composition according to claim 1, further comprising 5 to 90 parts by mass of (C) a polycarbonate resin, based on 100 parts by mass of (A) the polybutylene terephthalate resin.

4. 3. The polybutylene terephthalate resin composition for laser welding according to claim 1 or 2, further comprising 1 to 25 parts by mass of a styrene-based resin containing a rubber component (D) blended with 100 parts by mass of the polybutylene terephthalate resin (A).

5. 3. The laser welding polybutylene terephthalate resin composition according to claim 1, further comprising 0.05 to 5 parts by mass of a nucleating agent (E) per 100 parts by mass of the polybutylene terephthalate resin (A).

6. 3. The polybutylene terephthalate resin composition for laser welding according to claim 1, wherein a molded article made of the polybutylene terephthalate resin composition has a laser beam transmittance of 15% or more at a wavelength of 940 nm measured on a sample having a thickness of 2 mm.

7. 3. The polybutylene terephthalate resin composition for laser welding according to claim 1 or 2, wherein, in the relationship between the amount of iron oxide contained in the (B) glass fiber and the laser beam transmittance at a wavelength of 940 nm measured on a sample of 2 mm thick of a molded article made of the polybutylene terephthalate resin composition using the (B) glass fiber, when the content of the amount of iron oxide in the (B) glass fiber is 0.10 to 0.30 mass%, the absolute value of the slope obtained by the least squares method is 50 or less.

8. A molded article obtained by molding the laser weldable polybutylene terephthalate resin composition according to claim 1 or 2.

9. A method for improving the laser transmittance of a polybutylene terephthalate resin composition by blending 15 to 91 parts by mass of (B) glass fiber with 100 parts by mass of (A) polybutylene terephthalate resin, and adjusting the ratio of divalent iron oxide to 80 mass% or less of the iron oxide contained in the (B) glass fiber.

10. (B) A method for reducing fluctuations in laser transmittance of a polybutylene terephthalate resin composition due to fluctuations in the content of iron oxide in the glass fiber, by blending 15 to 91 parts by mass of glass fiber (B) with 100 parts by mass of polybutylene terephthalate resin (A), and adjusting the ratio of divalent iron oxide to 80 mass% or less among the iron oxide contained in the glass fiber (B).

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