Resin compositions, pellets, and molded articles

Abstract

To provide a resin composition, pellets, and molded articles that offer a good balance of tracking resistance, blackness, mechanical strength, and low warping. [Solution] The resin composition according to the present disclosure comprises a polybutylene terephthalate resin, an acrylonitrile styrene resin, an acrylic elastomer, carbon black, and glass fibers, wherein the acrylonitrile styrene resin content is 10 to 100 parts by mass per 100 parts by mass of the polybutylene terephthalate resin, the acrylic elastomer content is 5 to 50 parts by mass per 100 parts by mass of the polybutylene terephthalate resin, the carbon black content is 0.20 to 0.35 parts by mass per 100 parts by mass of the polybutylene terephthalate resin, and the glass fiber content is 10 to 120 parts by mass per 100 parts by mass of the polybutylene terephthalate resin, and the polyethylene terephthalate resin content in the resin composition is less than 6% by mass.

Description

[Technical Field]

[0001] This invention relates to resin compositions, pellets, and molded articles. [Background technology]

[0002] Polybutylene terephthalate resin is used in many applications, including automotive parts, electrical and electronic components, and precision instrument parts, due to its ease of molding, excellent mechanical properties, heat resistance, chemical resistance, fragrance retention, and other physical and chemical properties. In recent years, polybutylene terephthalate resin compositions with excellent tracking resistance have also been investigated (Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-106078 [Overview of the project] [Problems that the invention aims to solve]

[0004] Polybutylene terephthalate resin is inherently a resin with excellent tracking resistance. However, when carbon black is added to molded products made from polybutylene terephthalate resin to enhance their aesthetic appeal, their tracking resistance deteriorates. Furthermore, glass fibers are sometimes added to polybutylene terephthalate resin to improve the mechanical strength of molded products, but such molded products also suffer from poor tracking resistance. Furthermore, polybutylene terephthalate resin is inherently prone to warping. To suppress warping, it is conceivable to blend an amorphous resin with polybutylene terephthalate resin. However, blending an amorphous resin may result in inferior mechanical strength of the resulting molded product. The present invention has been made to solve the above problems, and aims to provide a resin composition, a pellet, and a molded article capable of providing a molded article that is excellently balanced in tracking resistance, blackness, mechanical strength, and low warpage property. [MEANS FOR SOLVING THE PROBLEMS]

[0005] As a result of investigations by the present inventors under the above circumstances, it has been found that the above problems can be solved by using an acrylonitrile-styrene resin as the amorphous resin and further blending an acrylic elastomer in a resin composition containing a polybutylene terephthalate resin, an amorphous resin, carbon black, and glass fibers. Specifically, the above problems are solved by the following means. [1] A resin composition comprising a polybutylene terephthalate resin (A), an acrylonitrile-styrene resin (B), an acrylic elastomer (C), carbon black, and glass fibers, wherein the content of the acrylonitrile-styrene resin is 10 to 100 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin, the content of the acrylic elastomer is 3 to 50 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin, the content of the carbon black is 0.20 to 0.35 parts by mass relative to 100 parts by mass in total of the polybutylene terephthalate resin (A), the acrylonitrile-styrene resin (B), and the acrylic elastomer (C), and the content of the glass fibers is 10 to 120 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin, wherein the content of the polyethylene terephthalate resin in the resin composition is less than 6% by mass. [2] The resin composition according to [1], wherein the content of the acrylic elastomer is 3 to 30 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin. [3] The resin composition according to [1] or [2], wherein the acrylic elastomer comprises a core-shell elastomer. [4] The L value of the resin composition measured in accordance with JIS Z 8722 and JIS Z 8781-4 * is less than 31, the resin composition according to any one of [1] to [3]. [5] The resin composition according to any one of [1] to [4], wherein the tracking resistance of the resin composition measured in accordance with IEC 60112 satisfies 400 V or higher. [6] The content of the acrylic elastomer is 3 to 30 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin, the acrylic elastomer comprises a core-shell elastomer, The L value of the resin composition measured in accordance with JIS Z 8722 and JIS Z 8781-4 * is less than 31, the tracking resistance of the resin composition measured in accordance with IEC 60112 satisfies 400 V or higher, the resin composition according to any one of [1] to [5]. [7] A pellet of the resin composition according to any one of [1] to [6]. [8] A molded article formed from the resin composition according to any one of [1] to [6]. [9] A molded article formed from the pellet according to [7].

Effects of the Invention

[0006] According to the present invention, it has become possible to provide a resin composition, a pellet, and a molded article that can provide a molded article excellent in well-balanced tracking resistance, blackness, mechanical strength, and low warpage property.

Modes for Carrying Out the Invention

[0007] Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an illustration for describing the present invention, and the present invention is not limited only to the present embodiment. In this specification, "~" is used to mean that the numbers before and after it are included as the lower and upper limits. "A~B" means that it is greater than or equal to A and less than or equal to B. Furthermore, the upper and lower limits of the numerical values ​​in this specification are given as examples of this embodiment, regardless of the combination of upper and lower limits.

[0008] In this specification, a preferred combination of embodiments is a more preferred embodiment. In this specification, all physical properties and characteristic values ​​shall be those at 23°C unless otherwise specified. In this specification, unless otherwise specified, the weight-average molecular weight is the polystyrene equivalent value measured by GPC (gel permeation chromatography) using a Tosoh HLC-8320GPC EcoSEC, tetrahydrofuran as the solvent, Shodex KF-G, KF-805L×3, and KF-800D columns, at a column temperature of 40°C and a flow rate of 1.2 mL / min, detected at a detection wavelength of 254 nm.

[0009] If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods, etc., described in the standards shown in this specification have been discontinued as of January 1, 2024, the standards in effect at the time of discontinuation shall apply.

[0010] The resin composition of this embodiment comprises polybutylene terephthalate resin, acrylonitrile styrene resin, acrylic elastomer, carbon black, and glass fiber, wherein the content of the acrylonitrile styrene resin is 10 to 100 parts by mass per 100 parts by mass of the polybutylene terephthalate resin. The resin composition is characterized in that the acrylic elastomer content is 3 to 50 parts by mass per 100 parts by mass of polybutylene terephthalate resin, the carbon black content is 0.20 to 0.35 parts by mass per 100 parts by mass of the total of polybutylene terephthalate resin (A), acrylonitrile styrene resin (B), and acrylic elastomer (C), and the glass fiber content is 10 to 120 parts by mass per 100 parts by mass of polybutylene terephthalate resin, wherein the polyethylene terephthalate resin content in the resin composition is less than 6% by mass. By adopting this configuration, a resin composition can be obtained that provides molded products with a good balance of tracking resistance, blackness, mechanical strength, and low warping. Polybutylene terephthalate resin inherently possesses excellent tracking resistance. However, when carbon black is added to polybutylene terephthalate resin, the tracking resistance of the resulting molded product deteriorates. Similarly, when glass fibers are incorporated into polybutylene terephthalate resin, the resulting molded product exhibits poor tracking resistance. On the other hand, if amorphous resin is added to polybutylene terephthalate resin to compensate for the reduced tracking resistance, the resulting molded product may have inferior mechanical strength. Under these circumstances, in this embodiment, an elastomer is added to the polybutylene terephthalate resin to compensate for the decrease in tracking resistance caused by the addition of carbon black and glass fibers. By adding an elastomer, it is expected that both tracking resistance will be improved and mechanical strength will be restored. However, excessive addition of elastomer can actually result in a lower mechanical strength in the resulting molded product. In this embodiment, an acrylic elastomer was used as the elastomer, and acrylonitrile styrene resin (AS resin) was used as the amorphous resin. By using an acrylic elastomer and AS resin, the compatibility between these components and the polybutylene terephthalate resin was improved, and it is presumed that the resulting molded product achieved low warpage while maintaining high mechanical strength. Furthermore, under the above circumstances, it is presumed that by precisely adjusting the amount of carbon black used, it was possible to maintain the black color while effectively suppressing the deterioration of tracking resistance. Furthermore, since the incorporation of polyethylene terephthalate resin tends to result in inferior tracking resistance of the resulting molded product, it is presumed that setting an upper limit on the polyethylene terephthalate resin content in the resin composition effectively suppressed the deterioration of tracking resistance.

[0011] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0012] <Polybutylene terephthalate resin> The resin composition of this embodiment includes a polybutylene terephthalate resin. Polybutylene terephthalate resin is a resin obtained by polycondensation of terephthalic acid as the main component of the acid component and 1,4-butanediol as the main component of the diol component. When the main component of the acid component is terephthalic acid, it means that 50% or more by mass of the acid component is terephthalic acid, preferably 60% or more by mass, more preferably 70% or more by mass, and may be 80% or more by mass, 90% or more by mass, or 95% or more by mass. When the main component of the diol component is 1,4-butanediol, it means that more than 50% by mass of the diol component is 1,4-butanediol, preferably 60% or more by mass, more preferably 70% or more by mass, and may be 80% or more by mass, 90% or more by mass, or 95% or more by mass. When polybutylene terephthalate resin contains other acidic components, examples include isophthalic acid and dimer acid. Furthermore, when polybutylene terephthalate resin contains other diol components, examples include polyalkylene glycols such as polytetramethylene glycol (PTMG).

[0013] When using a copolymer of polytetramethylene glycol as the polybutylene terephthalate resin, the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass.

[0014] When using dimer acid copolymerized polybutylene terephthalate as the polybutylene terephthalate resin, the proportion of the dimer acid component to the total carboxylic acid component is preferably 0.5 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 3 to 15 mol% as carboxylic acid groups. Such copolymerization ratios tend to result in an excellent balance between long-term heat resistance and toughness, which is preferable.

[0015] When using isophthalic acid copolymerized polybutylene terephthalate as the polybutylene terephthalate resin, the proportion of isophthalic acid components to the total carboxylic acid components is preferably 1 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 3 to 15 mol%. Such copolymerization ratios tend to result in an excellent balance of heat resistance, injection moldability, and toughness, which is preferable.

[0016] The polybutylene terephthalate resin used in this embodiment is preferably a resin (polybutylene terephthalate homopolymer) in which 90% or more by mass of the acid component is terephthalic acid and 90% or more by mass of the diol component is 1,4-butanediol, or a copolymerized polybutylene terephthalate resin obtained by copolymerizing polytetramethylene glycol, or an isophthalic acid copolymerized polybutylene terephthalate resin.

[0017] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 dL / g or higher, more preferably 0.6 dL / g or higher, preferably 2.0 dL / g or lower, more preferably 1.5 dL / g or lower, and even more preferably 1.1 dL / g or lower. Using a polybutylene terephthalate resin with an intrinsic viscosity of 0.5 dL / g or higher tends to improve the mechanical strength of the resulting molded product. Furthermore, using a polybutylene terephthalate resin with an intrinsic viscosity of 2.0 dL / g or lower tends to improve the fluidity of the polybutylene terephthalate resin and thus improve moldability. The intrinsic viscosity of polybutylene terephthalate resin is measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol. If the mixture contains two or more types of polybutylene terephthalate resin, the intrinsic viscosity shall be the intrinsic viscosity of the mixture.

[0018] The amount of terminal carboxyl groups in polybutylene terephthalate resin can be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By limiting the amount of terminal carboxyl groups to 50 eq / ton or less, gas generation during melt molding of polybutylene terephthalate resin can be more effectively suppressed. There is no specific lower limit for the amount of terminal carboxyl groups, but it is usually 5 eq / ton. When two or more types of polybutylene terephthalate resins are included, the amount of terminal carboxyl groups shall be the amount of terminal carboxyl groups in the mixture.

[0019] The amount of terminal carboxyl groups in polybutylene terephthalate resin can be determined by dissolving 0.5 g of polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. Methods for adjusting the amount of terminal carboxyl groups include adjusting polymerization conditions such as the raw material ratio, polymerization temperature, and reduced pressure method during polymerization, as well as reacting with end-sealing agents, and any other conventionally known methods.

[0020] The polybutylene terephthalate resin used in this embodiment may be recycled polybutylene terephthalate resin (including recovered products, material recycled products, chemical recycled products, etc.), rejected products, or scraps generated when molding molded products from a polybutylene terephthalate resin composition.

[0021] The polybutylene terephthalate resin content in the resin composition of this embodiment is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and may be 35% by mass or more, and also preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and may be 38% by mass or less. Setting it above the lower limit tends to further improve mechanical strength. Setting it below the upper limit tends to further improve low warpage. The resin composition of this embodiment may contain only one type of polybutylene terephthalate resin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0022] Furthermore, the polyethylene terephthalate resin content in the resin composition of this embodiment is less than 6% by mass. By keeping the polyethylene terephthalate resin content below the upper limit, tracking resistance can be further improved. The content of the polyethylene terephthalate resin is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and may be 0.5% by mass or less.

[0023] <Acrylonitrile styrene resin> The resin composition of this embodiment includes acrylonitrile styrene resin (AS resin). By incorporating acrylonitrile styrene resin, the resulting molded product can be made less warped and its tracking resistance can be improved. In this embodiment, the acrylonitrile styrene resin preferably contains an acrylonitrile-styrene-acrylate copolymer and / or an acrylonitrile-butadiene-styrene copolymer, and more preferably contains an acrylonitrile-styrene copolymer.

[0024] Here, the acrylonitrile styrene resin has a total amount of acrylonitrile units, styrene units, and acrylate units as needed that is 80% by mass or more of the total, preferably 85% by mass, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may also be 97% by mass or more, 98% by mass or more, 99% by mass or more, and may be 100% by mass or less. Furthermore, the acrylonitrile unit content in the acrylonitrile styrene resin is preferably 20% by mass or more, preferably 25% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less.

[0025] Styrene units refer to styrene units and substituted styrene units. Examples of styrene and substituted styrenes include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and tert-butylstyrene.

[0026] The acrylonitrile styrene resin used in this embodiment may have reactive functional groups such as epoxy groups, but it is preferable that it does not.

[0027] The melt volume rate (MVR) of acrylonitrile styrene resin at 220°C and a load of 10 kgf, according to the ISO 1133 standard, is 0.5 cm³. 3 / Preferably 10 minutes or more, 1 cm3 / 10 minutes or more is more preferable, 2 cm 3 / 10 minutes or more is further preferable, 3 cm 3 / 10 minutes or more is even more preferable. By setting the value to be not less than the aforementioned lower limit, the compatibility with the polybutylene terephthalate resin tends to be improved, and the surface appearance tends to be ameliorated. In addition, the melt volume rate (MVR) of the acrylonitrile styrene resin is preferably 60 cm 3 / 10 minutes or less, more preferably 40 cm 3 / 10 minutes or less, more preferably 10 cm 3 / 10 minutes or less, even more preferably 7 cm 3 / 10 minutes or less is still further preferable. By setting the value to be not more than the aforementioned upper limit, the low warpage property of the obtained molded article tends to be further improved. When the resin composition in the present embodiment contains two or more types of acrylonitrile styrene resins, the MVR of the mixture is used.

[0028] The weight average molecular weight of the acrylonitrile styrene resin is preferably 50,000 or more, more preferably 80,000 or more, and further preferably 100,000 or more. By setting the value to be not less than the aforementioned lower limit, the low warpage property of the obtained molded article tends to be further improved. In addition, the weight average molecular weight of the acrylonitrile styrene resin is preferably 500,000 or less, further preferably 400,000 or less, even more preferably 300,000 or less, and still more preferably 200,000 or less. By setting the value to be not more than the aforementioned upper limit, the probability of the presence of the acid-modified polymer, and by extension, the acid (acid group) on the surface of the obtained molded article increases, the adhesiveness of the resin composition to other members tends to be further improved, the compatibility with the polybutylene terephthalate resin is enhanced, and the surface appearance tends to be ameliorated. When the resin composition in the present embodiment contains two or more types of acrylonitrile styrene resins, the weight average molecular weight of the mixture is used.

[0029] The acrylonitrile styrene resin used in the present embodiment may include a recycled product. Examples of acrylonitrile styrene resin include those obtained through material recycling, which involves crushing and washing molded product scraps, rejected products, and collected used polyester resin molded products for reuse, as well as those obtained through chemical recycling (chemical decomposition method).

[0030] The acrylonitrile styrene resin content in the resin composition of this embodiment is 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, depending on the application, it may be 50 parts by mass or more, 60 parts by mass or more, or 70 parts by mass or more, or 100 parts by mass or less, preferably 90 parts by mass or less, more preferably 85 parts by mass or less, depending on the application, it may be 80 parts by mass or less, 70 parts by mass or less, or 60 parts by mass or less. Setting it above the lower limit tends to further improve the effect of suppressing the deterioration of mechanical properties. Also, setting it below the upper limit tends to further improve low warpage. The resin composition of this embodiment may contain only one type of acrylonitrile styrene resin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0031] <Mass ratio of polybutylene terephthalate resin to acrylonitrile styrene resin> In the resin composition of this embodiment, the mass ratio of polybutylene terephthalate resin to acrylonitrile styrene resin is 70 / 25 to 50 / 50. More specifically, the content of polybutylene terephthalate resin is preferably 55 parts by mass or more, more preferably 58 parts by mass or more, and preferably 65 parts by mass or less, per 100 parts by mass of the total of polybutylene terephthalate resin and acrylonitrile styrene resin. Setting the value above the lower limit tends to further improve the low warpage of molded articles obtained from the resin composition. Conversely, setting the value below the upper limit tends to further improve the basic physical properties of molded articles obtained from the resin composition, including heat resistance.

[0032] <Acrylic elastomer> The resin composition of this embodiment includes an acrylic elastomer. The inclusion of the elastomer improves tracking resistance. Furthermore, the use of an acrylic elastomer provides excellent compatibility with acrylonitrile resin and also improves compatibility with polybutylene terephthalate resin, resulting in a well-balanced and effective expression of the effects of the present invention. The elastomer used in this embodiment preferably includes a core-shell elastomer. The core-shell elastomer is preferably an acrylic-styrene rubber having a core-shell structure.

[0033] The polymer components forming the core layer typically have a glass transition temperature of 0°C or lower, preferably -10°C or lower, more preferably -20°C or lower, and even more preferably -30°C or lower. Specific examples of polymer components forming the core layer include polybutadiene, polyisoprene, polyalkyl acrylates such as polybutyl acrylate, poly(2-ethylhexyl acrylate), and butyl acrylate-2-ethylhexyl acrylate copolymers, silicone rubbers such as polyorganosiloxane rubber, butadiene-acrylic composites, IPN (Interpenetrating Polymer Network) type composite rubbers consisting of polyorganosiloxane rubber and polyalkyl acrylate rubber, styrene-butadiene copolymers, ethylene-α-olefin copolymers such as ethylene-propylene copolymers, ethylene-butene copolymers, and ethylene-octene copolymers, ethylene-acrylic copolymers, and fluororubber. These may be used individually or in combination of two or more. Among these, polybutadiene, polyalkyl acrylate, polyorganosiloxane, composites consisting of polyorganosiloxane and polyalkyl acrylate, and butadiene-styrene copolymer are preferred in terms of mechanical properties and surface appearance.

[0034] Specific examples of monomer components that can be graft copolymerized with the polymer component of the core layer and constitute the shell layer include (meth)acrylic acid ester compounds, (meth)acrylic acid compounds, and epoxy group-containing (meth)acrylic acid ester compounds such as glycidyl (meth)acrylate. These monomer components may be used individually or in combination of two or more. Among these, (meth)acrylic acid ester compounds and (meth)acrylic acid compounds are preferred, and (meth)acrylic acid ester compounds are more preferred, in terms of mechanical properties and surface appearance. Specific examples of (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and octyl (meth)acrylate. Among these, methyl (meth)acrylate and ethyl (meth)acrylate are preferred because they are relatively easy to obtain, and methyl (meth)acrylate is more preferred. Here, "(meth)acrylic" is a general term for "acrylic" and "methacrylic".

[0035] Among the core-shell elastomers, a core-shell elastomer is particularly preferred, comprising a core layer consisting of at least one polymer component selected from polybutadiene-containing rubber, polybutyl acrylate-containing rubber, polyorganosiloxane rubber, and IPN-type composite rubber consisting of polyorganosiloxane rubber and polyalkyl acrylate rubber, and a shell layer formed around it by graft copolymerization of (meth)acrylic acid ester. In the core-shell elastomer, it is preferable that the polymer component of the core layer is contained in an amount of 40% by mass or more, and more preferably 60% by mass or more. Furthermore, it is preferable that the (meth)acrylic acid ester component of the shell layer is contained in an amount of 10% by mass or more.

[0036] Preferred specific examples of these core-shell elastomers include methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), methyl methacrylate-butadiene copolymer (MB), methyl methacrylate-acrylic rubber copolymer (MA), methyl methacrylate-acrylic rubber-styrene copolymer (MAS), methyl methacrylate-acrylic / butadiene rubber copolymer, methyl methacrylate-acrylic / butadiene rubber-styrene copolymer, and methyl methacrylate-(acrylic / silicone composite) copolymer.

[0037] Examples of such core-type elastomers include "Paraloid® EXL2602", "Paraloid® EXL2603", "Paraloid® EXL2655", "Paraloid® EXL2311", "Paraloid® EXL2313", "Paraloid® EXL2315", "Paraloid® KM330", "Paraloid® KM336P", and "Paraloid® KCZ201" from Dow Chemical Japan Ltd., and Mitsubishi Rayon. Examples include Yon Co.'s "Metablen (registered trademark) E-901", "Metablen (registered trademark) S-2001", "Metablen (registered trademark) W-450A", and "Metablen (registered trademark) W-600A", and Kaneka Corporation's "Kaneace (registered trademark) M-511", "Kaneace (registered trademark) M-600", "Kaneace (registered trademark) M-400", "Kaneace (registered trademark) M-580", "Kaneace (registered trademark) M-590", "Kaneace (registered trademark) M-591", and "Kaneace (registered trademark) MR-01".

[0038] The acrylic elastomer content in the resin composition of this embodiment is 3 parts by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and also 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of polybutylene terephthalate resin. Setting the content above the lower limit tends to further improve the effect of suppressing the deterioration of mechanical properties. Furthermore, setting the content below the upper limit tends to further improve tracking resistance. The resin composition of this embodiment may contain only one type of acrylic elastomer, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0039] <Carbon Black> The resin composition of this embodiment contains carbon black. There is no specific type of carbon black required; any known carbon black, such as acetylene black, lamp black, thermal black, furnace black, channel black, or Ketjen black, can be used. In the resin composition of this embodiment, it is preferable to use carbon black in a masterbatch made of a thermoplastic resin (preferably polyester resin, more preferably polybutylene terephthalate resin). The concentration of carbon black in the masterbatch is preferably 1 to 50% by mass.

[0040] The carbon black content in the resin composition of this embodiment is preferably 0.20 parts by mass or more, and preferably 0.25 parts by mass or more, and preferably 0.35 parts by mass or less, and preferably 0.30 parts by mass or less, based on 100 parts by mass of the total of the polybutylene terephthalate resin (A), acrylonitrile styrene resin (B), and acrylic elastomer (C). Setting the content above the lower limit allows for sufficient blackness to be imparted to the molded product. Setting the content below the upper limit tends to more effectively suppress the decrease in the tracking resistance of the molded product. The resin composition of this embodiment may contain only one type of carbon black, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0041] <Glass fiber> The resin composition of this embodiment contains glass fibers. By including glass fibers, the mechanical strength of the resulting molded product can be further improved.

[0042] In this embodiment, the glass fibers have a number-average fiber length of 0.5 to 10 mm, and more preferably 1 to 5 mm. By using glass fibers with such a number-average fiber length, the mechanical strength can be further improved. The number-average fiber length is calculated by randomly selecting glass fibers to be measured from an image obtained by observation with an optical microscope, measuring their longest side, and then calculating the number-average fiber length from the obtained measurement values. The observation magnification is 20x, and the number of measurements is 1,000 or more. This roughly corresponds to the cut length. Furthermore, the cross-section of the glass fiber may be circular, elliptical, oblong, rectangular, a rectangle with semicircles attached to both short sides, or cocoon-shaped, but a circular shape is preferred. Here, "circular" includes not only a circular shape in the geometric sense, but also what is commonly referred to as circular in the technical field of this embodiment. The number-average fiber diameter of glass fibers is preferably 4.0 μm or more at the lower limit, more preferably 4.5 μm or more, and even more preferably 5.0 μm or more. The upper limit of the number-average fiber diameter of glass fibers is preferably 15.0 μm or less, and more preferably 14.0 μm or less. Using glass fibers having a number-average fiber diameter within this range tends to yield molded products with superior mechanical strength. The number-average fiber diameter of glass fibers is calculated by randomly selecting glass fibers to be measured from an image obtained by observing with an electron microscope, measuring the fiber diameter near the center, and obtaining the measured values. The observation magnification is 1,000x, and the number of measurements is 1,000 or more. For glass fibers with a cross-section other than circular, the number-average fiber diameter is calculated as the number-average fiber diameter when converted to a circle with the same area as the cross-sectional area.

[0043] Glass fibers are generally obtained by melt-spinning supplied glass such as E glass (Electrical glass), C glass (Chemical glass), A glass (Alkali glass), S glass (High strength glass), D glass, R glass, and alkali-resistant glass, but any material that can be made into glass fibers can be used and is not particularly limited. In this embodiment, it is preferable to include E glass.

[0044] The glass fibers used in this embodiment are preferably surface-treated with a surface treatment agent such as a silane coupling agent, such as γ-methacrylateoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane. The amount of surface treatment agent applied is preferably 0.01 to 1% by mass of the glass fibers. Furthermore, if necessary, glass fibers may be surface-treated with a lubricant such as a fatty acid amide compound or silicone oil, an antistatic agent such as a quaternary ammonium salt, a resin with film-forming ability such as epoxy resin or urethane resin, or a mixture of a resin with film-forming ability and a heat stabilizer.

[0045] Glass fibers are available commercially. Examples of commercially available products include T-286H, T-187, T-756H, T-127, T-289H from Nippon Electric Glass Co., Ltd., DEFT2A from Owens Corning, HP3540 from PPG, and CSG3PA820 from Nitto Boseki Co., Ltd.

[0046] In the resin composition of this embodiment, the glass fiber content is 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, per 100 parts by mass of polybutylene terephthalate resin. Setting the content above the lower limit tends to increase the mechanical strength of the resulting molded product. The upper limit of the glass fiber content is 120 parts by mass or less, preferably 115 parts by mass or less, more preferably 110 parts by mass or less, and even more preferably 100 parts by mass or less, per 100 parts by mass of polybutylene terephthalate resin. Setting the content below the upper limit tends to increase the welding strength of the interface.

[0047] Furthermore, the glass fiber content in the resin composition of this embodiment is preferably 20% by mass or more, and more preferably 25% by mass or more. Moreover, the glass fiber content is preferably 45% by mass or less, more preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 32% by mass or less. The resin composition of this embodiment may contain only one type of glass fiber, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0048] <Release agent> The resin composition of this embodiment preferably contains a mold release agent. A wide range of known release agents can be used as the release agent, including, for example, aliphatic carboxylic acid amides, aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds with a number average molecular weight of 200 to 15000, and polysiloxane-based silicone oils, with aliphatic carboxylic acid amides and / or aliphatic hydrocarbon compounds with a number average molecular weight of 200 to 15000 being preferred.

[0049] Examples of aliphatic carboxylic acid amides include compounds obtained by the dehydration reaction of a higher aliphatic monocarboxylic acid and / or polybasic acid with a diamine. Preferred higher aliphatic monocarboxylic acids include saturated aliphatic monocarboxylic acids and hydroxycarboxylic acids having 16 or more carbon atoms, such as palmitic acid, stearic acid, behenic acid, montanic acid, and 12-hydroxystearic acid. Examples of polybasic acids include aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, sebacic acid, pimelic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid and terephthalic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and cyclohexylsuccinic acid. Examples of diamines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, metaxylylenediamine, tolylenediamine, paraxylylenediamine, phenylenediamine, and isophoronediamine. As carboxylic acid amide compounds, compounds obtained by polycondensation of stearic acid, sebacic acid, and ethylenediamine are preferred, and compounds obtained by polycondensation of 2 moles of stearic acid, 1 mole of sebacic acid, and 2 moles of ethylenediamine are even more preferred. In addition to bisamide compounds obtained by reacting diamines with aliphatic carboxylic acids, such as N,N'-methylenebisstearate and N,N'-ethylenebisstearate, dicarboxylic acid amide compounds such as N,N'-dioctadecylterephthalamide can also be suitably used.

[0050] Examples of aliphatic carboxylic acids include saturated or unsaturated aliphatic monovalent, divalent, or trivalent carboxylic acids. Here, aliphatic carboxylic acids also include alicyclic carboxylic acids. Among these, preferred aliphatic carboxylic acids are monovalent or divalent carboxylic acids having 6 to 36 carbon atoms, and more preferably aliphatic saturated monovalent carboxylic acids having 6 to 36 carbon atoms. Specific examples of such aliphatic carboxylic acids include palmitic acid, stearic acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melissic acid, tetrariacontanoic acid, montanic acid, adipic acid, and azelaic acid.

[0051] As the aliphatic carboxylic acid in the ester of an aliphatic carboxylic acid and an alcohol, for example, the same aliphatic carboxylic acid as the aliphatic carboxylic acid can be used. On the other hand, as the alcohol, for example, saturated or unsaturated monohydric or polyhydric alcohols can be used. These alcohols may have substituents such as fluorine atoms or aryl groups. Among these, monohydric or polyhydric saturated alcohols having 30 or fewer carbon atoms are preferred, and aliphatic or alicyclic saturated monohydric alcohols or aliphatic saturated polyhydric alcohols having 30 or fewer carbon atoms are more preferred. Specific examples of such alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol. Specific examples of esters of aliphatic carboxylic acids and alcohols include beeswax (a mixture mainly composed of myricyl palmitate), stearyl stearate, behenyl behenate, stearyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, and esters of montanic acid and polyfunctional alcohols.

[0052] Examples of aliphatic hydrocarbons with a number-average molecular weight of 200 to 15000 include liquid paraffin, paraffin wax, microwax, polyethylene wax, Fischer-Tropsch wax, and α-olefin oligomers having 3 to 12 carbon atoms. Note that alicyclic hydrocarbons are also included as aliphatic hydrocarbons. Furthermore, the number-average molecular weight of the aliphatic hydrocarbons is preferably 5000 or less.

[0053] Examples of polyolefin waxes include polyethylene wax, polypropylene wax, and polyethylene propylene wax, with polyethylene wax being preferred. The polyolefin wax may be unmodified or modified. Examples of modified polyolefin waxes include vinyl ester-modified polyolefin wax, acid-modified polyolefin wax, and oxidized polyolefin wax, with oxidized polyolefin wax being preferred. Oxidized polyolefin wax has excellent compatibility with polyalkylene terephthalate resin and tends to effectively suppress mold deposits in the resulting resin composition.

[0054] Oxidized polyolefin waxes can be obtained by oxidizing the corresponding unmodified polyolefin wax. Examples of oxidized polyethylene waxes include Licowax® PED521, PED522, PED121, and Ceridust® 3715, all manufactured by Clariant Chemicals. In addition to the above, commercially available polyolefin waxes can also be referenced to the description in paragraph 0028 of Japanese Patent Publication No. 2022-140470, which is incorporated herein by reference.

[0055] The weight-average molecular weight of the polyolefin wax is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, even more preferably 2,000 or more, and even more preferably 2,500 or more. Setting it above the lower limit tends to further shorten the growing time. Furthermore, the weight-average molecular weight of the polyolefin wax is preferably 30,000 or less, more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 10,000 or less. Setting it below the upper limit tends to further improve the fluidity of the resin composition during molding. The weight-average molecular weight was measured using GPC (gel permeation chromatography) with a Tosoh HLC-8320GPC EcoSEC, tetrahydrofuran as the solvent, three Shodex KF-G, KF-805L, and KF-800D columns, at a column temperature of 40°C and a flow rate of 1.2 mL / min. The measurement was obtained as a polystyrene equivalent value detected with a UV-8320 detector at a detection wavelength of 254 nm. In this embodiment, if the resin composition contains two or more types of polyolefin waxes, the weight-average molecular weight of the mixture is used.

[0056] The dropping point of the polyolefin wax is preferably 165°C or lower, more preferably 160°C or lower, even more preferably 155°C or lower, even more preferably 150°C or lower, even more preferably 145°C or lower, even more preferably 140°C or lower, even more preferably 135°C or lower, especially more preferably 130°C or lower, and also preferably 80°C or higher, more preferably 85°C or higher, even more preferably 85°C or higher, even more preferably 90°C or higher, and even more preferably 95°C or higher. The dropping point is defined as the temperature at which the first drop of molten polyolefin wax falls from a standard cup with a 2.8 mm opening after heating the wax from a solid to a liquid state.

[0057] In addition to the above, the descriptions in paragraphs 0063 to 0077 of Japanese Patent Publication No. 2018-070722 and paragraphs 0090 to 0098 of Japanese Patent Publication No. 2019-123809 can also be considered as release agents, and these contents are incorporated herein by reference.

[0058] The resin composition of this embodiment preferably contains 0.1 parts by mass or more of a release agent per 100 parts by mass of polybutylene terephthalate resin, more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. Setting the release agent above the lower limit tends to further improve the release properties of the resulting molded product. Furthermore, setting the release agent below the upper limit can effectively suppress bleed-out of the resulting molded product. The resin composition may contain only one type of release agent or two or more types. If it contains two or more types, it is preferable that the total amount is within the above range.

[0059] <Stabilizer> The resin composition of this embodiment may contain stabilizers (light stabilizers and / or heat stabilizers). The stabilizer preferably contains one or more compounds selected from the group consisting of thioether compounds, phosphorus compounds, hindered phenol compounds, and phosphite compounds, with phosphorus compounds and / or hindered phenol compounds being more preferred. Furthermore, in this embodiment, it is also preferable to use two or more thioether compounds, hindered phenol compounds, and phosphite compounds in combination as needed.

[0060] As the thioether compound, any conventionally known sulfur atom-containing compound can be used, with thioethers being particularly preferred. The resin composition of this embodiment tends to have a good appearance and improved thermal stability when it contains a thioether compound. Specifically, examples include didodecylthiodipropionate, ditetradecylthiodipropionate, dioctadecylthiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, and trilauryl trithiophosphite. Among these, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate] is preferred. Commercially available products include "C-NOX 412S" manufactured by Cipro Chemical Co., Ltd. and "ADEKA AO-412S" manufactured by ADEKA Corporation.

[0061] Examples of phosphorus-based stabilizers include phosphorous acid, phosphoric acid, phosphorous acid esters (phosphites), trivalent phosphate esters (phosphonites), and pentavalent phosphate esters (phosphates), with organic phosphite compounds, organic phosphonite compounds, and organic phosphate compounds being preferred.

[0062] Preferably, the following organic phosphate compounds are used. Expression (R 1 O) 3-n P(=O)OH n (In the formula, R 1 (where n is an alkyl group or an aryl group, which may be the same or different; n is an integer between 0 and 2.) It is a compound represented by . More preferably, R1 Examples include long-chain alkyl acid phosphate compounds having 8 to 30 carbon atoms. Specific examples of alkyl groups having 8 to 30 carbon atoms include octyl group, 2-ethylhexyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosyl group, and triacontyl group.

[0063] Examples of long-chain alkyl acid phosphates include octyl acid phosphate, 2-ethylhexyl acid phosphate, decyl acid phosphate, lauryl acid phosphate, octadecyl acid phosphate, oleyl acid phosphate, behenyl acid phosphate, phenyl acid phosphate, nonylphenyl acid phosphate, cyclohexyl acid phosphate, phenoxyethyl acid phosphate, and alkoxypolyethylene glycol acid phosphate. Examples include octadecyl acid phosphate, bisphenol A acid phosphate, dimethyl acid phosphate, diethyl acid phosphate, dipropyl acid phosphate, diisopropyl acid phosphate, dibutyl acid phosphate, dioctyl acid phosphate, di-2-ethylhexyl acid phosphate, dioctyl acid phosphate, dilauryl acid phosphate, distearyl acid phosphate, diphenyl acid phosphate, and bisnonylphenyl acid phosphate. Among these, octadecyl acid phosphate is preferred, and this is commercially available under the trade name "ADEKA Stab AX-71" from ADEKA Corporation.

[0064] Preferably, the organophosphite compound is of the following formula: R 2 OP(OR 3 )(OR 4 ) (In the formula, R 2 , R 3 and R 4 These are a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms, respectively.2 , R 3 and R 4 At least one of them is an aryl group with 6 to 30 carbon atoms. Examples of compounds represented by [the formula shown] are given.

[0065] Examples of organic phosphite compounds include triphenyl phosphite, tris(nonylphenyl) phosphite, dilauryl hydrogen phosphite, triethyl phosphite, tridecyl phosphite, tris(2-ethylhexyl) phosphite, tris(tridecyl) phosphite, tristearyl phosphite, diphenyl monodecyl phosphite, monophenyl didecyl phosphite, diphenyl mono(tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra(tridecyl)pentaerythritol tetraphosphite, hydrogenated bisphenol A phenol phosphite polymer, diphenyl hydrogen phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenyl di(tridecyl) phosphite), and tetra(tridecyl)4,4'-iso Examples include propyridene diphenyl diphosphite, bis(tridecyl)pentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, dilauryl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris(4-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, and bis(2,4-dicumylphenyl)pentaerythritol diphosphite. Among these, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is preferred.

[0066] The organic phosphonite compound is preferably one of the following formulas: R 5 -P(OR 6 )(OR 7 ) (In the formula, R 5 , R 6 and R 7 These are a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms, respectively. 5 , R 6 and R 7 At least one of them is an aryl group with 6 to 30 carbon atoms. Examples of compounds represented by [the formula shown] are given.

[0067] Examples of organic phosphonite compounds include tetrakis(2,4-di-iso-propylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-n-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,3'-biphenylenediphosphonite, and tetrakis(2,4-di-tert-butylphenyl)-3,3'-biphenylenediphosphona Examples include tetrakis(2,6-di-iso-propylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-n-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,3'-biphenylenediphosphonite, and tetrakis(2,6-di-tert-butylphenyl)-3,3'-biphenylenediphosphonite.

[0068] Examples of hindered phenol compounds include pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), pentaerythritol tetrakis(3-(3,5-di-neopentyl-4-hydroxyphenyl)propionate), and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene. Among these, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferred. Commercially available options include ADEKA products such as "ADEKA Stub AO-60" and "ADEKA Stub AO-330," and BASF products such as "Irganox Knox 1010."

[0069] Preferably, the phosphite compound is of the formula: R 2 OP(OR 3 )(OR 4 ) (In the formula, R 2 , R 3 and R 4 These are a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms, respectively. 2 , R 3 and R 4 At least one of them is an aryl group with 6 to 30 carbon atoms. Examples of compounds represented by [the formula shown] are given.

[0070] Phosphite compounds include, for example, triphenyl phosphite, tris(nonylphenyl) phosphite, dilauryl hydrogen phosphite, triethyl phosphite, tridecyl phosphite, tris(2-ethylhexyl) phosphite, tris(tridecyl) phosphite, tristearyl phosphite, diphenyl monodecyl phosphite, monophenyl didecyl phosphite, diphenyl mono(tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra(tridecyl)pentaerythritol tetraphosphite, hydrogenated bisphenol A phenol phosphite polymer, diphenyl hydrogen phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenyl di(tridecyl) phosphite, tetra(tridecyl)4,4'-isopropyl Examples include lopyridene diphenyl diphosphite, bis(tridecyl)pentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, dilauryl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris(4-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, and bis(2,4-dicumylphenyl)pentaerythritol diphosphite. Among these, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is preferred. A commercially available example is "ADEKA Stab PEP-36" manufactured by ADEKA Corporation.

[0071] In addition, as stabilizers, specific examples can be found in paragraphs 0067-0075 of Japanese Patent Publication No. 2021-063196, paragraphs 0046-0057 of Japanese Patent Publication No. 2018-070722, paragraphs 0030-0037 of Japanese Patent Publication No. 2019-056035, and paragraphs 0066-0078 of International Publication No. 2017 / 038949, the contents of which are incorporated herein by reference.

[0072] The stabilizer content in the resin composition of this embodiment is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and most preferably 0.5 parts by mass or more, per 100 parts by mass of polybutylene terephthalate resin contained in the resin composition. Setting the content above the lower limit tends to further improve the effect of suppressing thermal degradation and oxidative degradation of the resin during melt mixing, molding, and use as a molded product, and tends to improve heat resistance. Furthermore, the upper limit of the stabilizer content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less, per 100 parts by mass of polybutylene terephthalate resin. Setting the content below the upper limit tends to effectively suppress adverse effects on appearance and physical properties due to aggregation of additives such as stabilizers, and tends to suppress discoloration of the resin composition. The resin composition of this embodiment may contain only one stabilizer or two or more stabilizers. When two or more stabilizers are included, it is preferable that the total amount is within the above range.

[0073] <Other ingredients> The resin composition of this embodiment may contain other components as needed, as long as they do not significantly impair the desired physical properties. Examples of other components include various resin additives. Note that one of these other components may be included, or two or more may be included in any combination and ratio. The total amount of these resin additives is preferably 0 to 5% by mass, more preferably 0 to 3% by mass, and even more preferably 0 to 1% by mass, based on 100% by mass of the resin composition. Examples of resin additives include flame retardants, flame retardant enhancers, reactive compounds, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents. Furthermore, the resin composition of this embodiment may contain additives described in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, without departing from the spirit of the present invention, and this is incorporated herein. In this embodiment, the resin composition preferably contains polybutylene terephthalate resin, acrylonitrile styrene resin, acrylic elastomer, carbon black, and glass fibers totaling 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may also contain 100% by mass or less. Furthermore, in the resin composition of this embodiment, the total of polybutylene terephthalate resin, acrylonitrile styrene resin, acrylic elastomer, carbon black, glass fiber, and stabilizers and release agents added as needed preferably account for 90% or more by mass of the resin composition, more preferably 95% or more by mass, even more preferably 97% or more by mass, and may also account for 99% or more by mass, or 100% or less by mass.

[0074] <Physical properties of the resin composition> The resin composition of this embodiment preferably has a strong black color. Specifically, the L of the resin composition of this embodiment, measured according to JIS Z 8722 and JIS Z 8781-4, is preferred. * The value is preferably 25 or higher, preferably 26 or higher, more preferably 27 or higher, preferably less than 31, more preferably 30 or lower, and even more preferably 28 or lower. Setting the value above the lower limit tends to further improve the suppression of the decrease in tracking resistance. Also, setting the value below the upper limit tends to further improve the blackness of the molded product.

[0075] The resin composition of this embodiment preferably has excellent tracking resistance. More specifically, it is more preferable that the tracking resistance of the resin composition, as measured according to IEC 60112, is 400V or higher. The upper limit of the tracking resistance is exemplified by the upper limit of the measuring instrument (e.g., 600V). The L value and tracking resistance are measured according to the examples described below.

[0076] <Method for producing resin compositions> The resin composition of this embodiment can be manufactured by conventional methods for preparing resin compositions. Typically, each component and various additives added as desired are thoroughly mixed together and then melt-kneaded in a single-screw or twin-screw extruder. Alternatively, the resin composition of this embodiment can be prepared by melt-kneading the components without pre-mixing them, or by pre-mixing only a portion of them, and supplying them to the extruder using a feeder. Some components, such as carbon black, may be melt-kneaded with a thermoplastic resin (preferably polybutylene terephthalate resin) to prepare a masterbatch, and then the remaining components may be added to this and melt-kneaded. Furthermore, when using glass fibers, it is also preferable to supply them from a side feeder located midway through the extruder cylinder. The heating temperature during melt mixing can usually be selected appropriately from the range of 220 to 300°C. If the temperature is too high, decomposition gases are likely to be generated, which may cause opacity. Therefore, it is desirable to select a screw configuration that takes shear heating into consideration. To suppress decomposition during mixing and subsequent molding processes, it is desirable to use antioxidants and heat stabilizers. One embodiment of the resin composition is a pellet.

[0077] <Method for manufacturing molded products> The resin composition of this embodiment is molded according to a known method. The method for manufacturing the molded product is not particularly limited, and any molding method commonly used for resin compositions can be arbitrarily employed. Examples include injection molding, ultra-high-speed injection molding, injection compression molding, two-color molding, hollow molding methods such as gas-assisted molding, molding using a heat-insulating mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., with injection molding being preferred among them. Details of the injection molding method can be found in paragraphs 0113 to 0116 of Japanese Patent No. 6183822, and these contents are incorporated herein by reference. Furthermore, the mold temperature during mold molding, such as injection molding, is preferably between 40 and 150°C.

[0078] <Application> The resin composition of this embodiment is used as a molded article formed from the resin composition or pellets. The applications of the resin composition or molded article are not particularly limited, but it is preferably used in electrical and electronic equipment / components, office automation equipment / components, information terminal equipment / components, machine parts, home appliances, vehicle parts (automobile interior and exterior), building materials, various containers, leisure goods and miscellaneous goods, lighting equipment, etc. In particular, it is preferably used in vehicle parts for electric vehicles. [Examples]

[0079] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0080] 1.Raw materials The following ingredients were used. [Table 1]

[0081] 2. Examples 1-4, Comparative Examples 1-6 <Compound> Each component shown in Table 1 was uniformly mixed in a tumbler mixer in the proportions shown in Table 2 or Table 3 (each component in Tables 2 and 3 is shown in mass%), excluding the glass fibers. The resulting mixture was supplied to a twin-screw extruder (TEX30α, manufactured by Japan Steel Works, Ltd.) through the main feed port. The cylinder temperature of the first kneading section was set to 260°C, and the glass fibers were supplied from the side feeder. The resin composition, which was melt-kneaded under the conditions of a cylinder temperature of 220°C and a screw rotation speed of 200 rpm after the addition of the glass fibers, was rapidly cooled in a water bath and pelletized using a pelletizer to obtain pellets of the resin composition.

[0082] <Shrinkage rate> The pellets obtained above were dried at 120°C for 5 hours, and then molded into a product (100mm long, 100mm wide, 2.0mm thick) using a NEX80-9E injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd., with a cylinder temperature of 260°C and a mold temperature of 120°C. The resulting test specimens were conditioned at 23°C and 50% RH for more than 24 hours. Subsequently, the dimensions in the MD (Machine Direction, also called the flow direction) and TD (Transverse Direction, also called the perpendicular direction) directions were measured using the obtained test specimens, and the shrinkage rate (unit: %) was calculated based on the dimensions of the mold.

[0083] <Tensile strength> The pellets obtained as described above were dried at 120°C for 5 hours, and then 4 mm thick ISO test specimens were injection molded using an injection molding machine (Japan Steel Works, Ltd. "J85AD") under the conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. The tensile strength (in MPa) of the ISO test specimens (4 mm thick) obtained as described above was measured according to ISO 527-1 and ISO 527-2.

[0084] <Tracking Resistance (CTI)> The pellets obtained above were dried at 120°C for 5 hours. Then, using a NEX80-9E injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd., molded products (100 mm long, 100 mm wide, 3.0 mm thick) were formed at a cylinder temperature of 260°C and a mold temperature of 120°C. The resulting test pieces were conditioned at 23°C and 50% RH for more than 24 hours. Using the test specimens obtained above, tracking resistance was measured according to IEC 60112, with solution A as the measurement solution. All five test specimens that exceeded 51 drops at 400V and 101 drops at 375V, and thus met the 400V tracking resistance requirement, were designated as A. Test specimens that did not reach 51 drops in the 400V test or 101 drops in the 375V test, and therefore could not be said to have 400V tracking resistance, were designated as B.

[0085] <L * value> The pellets obtained above were dried at 120°C for 5 hours, and then molded into a product (100mm long, 100mm wide, 2.0mm thick) using a NEX80-9E injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd., with a cylinder temperature of 260°C and a mold temperature of 120°C. The resulting test specimens were conditioned at 23°C and 50% RH for more than 24 hours. Subsequently, the obtained test specimens were used to measure the color tone (L) using a Konica Minolta CM-36dg spectrophotometer. * a * , b * ) was measured. L * Those with a value of less than 31 and judged to have sufficient blackness are classified as A, L. * If the value is 31 or higher, and the color is judged to be insufficiently black, it is labeled as B.

[0086] [Table 2]

[0087] [Table 3]

[0088] As is clear from the above results, the resin composition of the present invention yielded molded articles with a good balance of tracking resistance, blackness, mechanical strength, and low warping (Examples 1-4). In contrast, when acrylic elastomers were not included (Comparative Examples 1 and 2), tracking resistance was poor. Also, when acrylonitrile styrene resin was not included (Comparative Examples 2 and 3), warping resistance was poor. Furthermore, if the carbon black content was too low, the blackness was insufficient, and if it was too high, tracking resistance was poor (Comparative Examples 4 and 5). In addition, when polyethylene terephthalate resin was excessively included (Comparative Example 6), tracking resistance was poor.

[0089] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. It contains polybutylene terephthalate resin (A), acrylonitrile styrene resin (B), acrylic elastomer (C), carbon black, and glass fiber. The content of the acrylonitrile styrene resin is 10 to 100 parts by mass per 100 parts by mass of polybutylene terephthalate resin. The content of the acrylic elastomer is 5 to 50 parts by mass per 100 parts by mass of polybutylene terephthalate resin. The carbon black content is 0.20 to 0.35 parts by mass per 100 parts by mass of the total of polybutylene terephthalate resin (A), acrylonitrile styrene resin (B), and acrylic elastomer (C). The resin composition contains 10 to 120 parts by mass of glass fibers per 100 parts by mass of polybutylene terephthalate resin, A resin composition wherein the content of polyethylene terephthalate resin in the resin composition is less than 6% by mass.

2. The resin composition according to claim 1, wherein the content of the acrylic elastomer is 3 to 30 parts by mass per 100 parts by mass of polybutylene terephthalate resin.

3. The resin composition according to claim 1 or 2, wherein the acrylic elastomer includes a core-shell elastomer.

4. L measured according to JIS Z 8722 and JIS Z 8781-4 for the resin composition. ＊ The resin composition according to claim 1 or 2, wherein the value is less than 31.

5. The resin composition according to claim 1 or 2, wherein the tracking resistance of the resin composition, as measured according to IEC 60112, is 400V or more.

6. The content of the acrylic elastomer is 3 to 30 parts by mass per 100 parts by mass of polybutylene terephthalate resin. The acrylic elastomer includes a core-shell elastomer. L measured according to JIS Z 8722 and JIS Z 8781-4 for the resin composition. ＊ The value is less than 31, The resin composition according to claim 1, wherein the tracking resistance of the resin composition, as measured in accordance with IEC 60112, is 400V or more.

7. Pellets of the resin composition according to claim 1, 2, or 6.

8. A molded article formed from the resin composition according to claim 1, 2, or 6.

9. A molded article formed from the pellets described in claim 7.

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