Poly(butylene terephthalate) resin composition

Abstract

Provided is a low gloss poly(butylene terephthalate) resin composition which exhibits excellent jet-blackness and has little gloss unevenness.　A poly(butylene terephthalate) resin composition according to the present invention contains: (A) a poly(butylene terephthalate) resin; (B) a polycarbonate resin; (C) glass flakes; and (D) carbon black. The poly(butylene terephthalate) resin (A) includes (a1) a modified poly(butylene terephthalate) resin containing 5-30 mol% of a comonomer unit. The glass flakes (C) have an average thickness of 1 µm or less and a median diameter of 5-70 μm. Relative to 100 parts by mass of the poly(butylene terephthalate) resin (A), the content of the polycarbonate resin (B) is 60-100 parts by mass, the content of the glass flakes (C) is 60-100 parts by mass, and the content of the carbon black (D) is 0.8-15 parts by mass.

Description

Polybutylene terephthalate resin composition

[0001] The present disclosure relates to polybutylene terephthalate resin compositions.

[0002] Components of optical devices such as drive recorders, backup cameras, and ADAS mounted on vehicles such as automobiles, and components of display devices such as head-up displays, liquid crystal meters, and car navigation systems are required to have low gloss in order to reduce glare due to reflections, etc. Many plastic materials form a high-gloss surface when molded, so low gloss is achieved by providing a texture on the molded product surface by providing a texture on the mold used for injection molding, or by coating the surface of the molded product with a matting agent. Attempts to achieve low gloss by utilizing the properties of the material itself are described, for example, in Patent Documents 1 and 2.

[0003] JP 2008-540803 A JP 2018-144581 A

[0004] An object of the present disclosure is to provide a polybutylene terephthalate resin composition that has excellent jet blackness and low gloss with little gloss unevenness.

[0005] The present disclosure includes the following aspects: [1] A polybutylene terephthalate resin composition comprising (A) a polybutylene terephthalate resin, (B) a polycarbonate resin, (C) glass flakes, and (D) carbon black, wherein the (A) polybutylene terephthalate resin comprises (a1) a modified polybutylene terephthalate resin comprising 5 to 30 mol % of a comonomer unit, the (C) glass flakes having an average thickness of 1 μm or less and a median diameter of 5 to 70 μm, and wherein, relative to 100 parts by mass of the (A) polybutylene terephthalate resin, the content of the (B) polycarbonate resin is 60 to 100 parts by mass, the content of the (C) glass flakes is 60 to 100 parts by mass, and the content of the (D) carbon black is 0.8 to 15 parts by mass. [2] The polybutylene terephthalate resin composition according to [1], further comprising (F) a phosphorus-based compound. [3] A molded article comprising the resin composition according to [1] or [2].

[0006] According to the present disclosure, it is possible to provide a polybutylene terephthalate resin composition having excellent jet blackness and low gloss with little gloss unevenness.

[0007] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limit values ​​are described for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limit values ​​of a numerical range described in this disclosure are numerical values ​​within that range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or greater and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments. Each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications of configurations are possible as appropriate within the spirit of the present disclosure.

[0008] [Polybutylene terephthalate resin composition] The polybutylene terephthalate resin composition (hereinafter also simply referred to as "resin composition") of the present disclosure comprises (A) a polybutylene terephthalate resin, (B) a polycarbonate resin, (C) glass flakes, and (D) carbon black, wherein the (A) polybutylene terephthalate resin comprises (a1) a modified polybutylene terephthalate resin containing 5 to 30 mol% of a comonomer unit, the (C) glass flakes have an average thickness of 1 μm or less and a median diameter of 5 to 70 μm, and the content of the (B) polycarbonate resin is 60 to 100 parts by mass, the content of the (C) glass flakes is 60 to 100 parts by mass, and the content of the (D) carbon black is 0.8 to 15 parts by mass, relative to 100 parts by mass of the (A) polybutylene terephthalate resin.

[0009] When light is incident on the surface of a molded article, light reflection, transmission, and absorption occur. From the perspective of increasing light absorption and reducing light reflection on the surface of a molded article, it is preferable for the resin composition to have excellent jet-black properties. Traditionally, black coloring has been achieved by blending carbon black into resin compositions, but depending on the composition of the resin composition, sufficient jet-blackness may not be achieved even with the addition of carbon black. Furthermore, since high reflection of light on the surface of a molded article increases gloss, it is preferable to reduce the reflected light. Increasing the light transmittance of a resin material is expected to allow light to enter the interior of the molded article and reduce reflected light, but excessive light transmittance may result in increased gloss or decreased jet-blackness. Furthermore, changes in the injection speed during injection molding of a resin composition may result in uneven gloss in the resulting molded article. In particular, molded articles with complex shapes may have uneven gloss due to different resin filling speeds at different locations in the molded article, even when multi-stage speed control is used. By virtue of having the above-described configuration, the resin composition of the present disclosure can achieve both excellent jet blackness and low gloss, and can provide a molded article with little gloss unevenness.

[0010] In the present disclosure, the term "polybutylene terephthalate resin composition" refers to a resin composition containing a polybutylene terephthalate resin. The content of the polybutylene terephthalate resin will be described later.

[0011] <(A) Polybutylene Terephthalate Resin> The (A) polybutylene terephthalate resin contains (a1) a modified polybutylene terephthalate resin containing 5 to 30 mol % of a comonomer unit (hereinafter also referred to simply as "(a1) modified polybutylene terephthalate resin"). By including the (a1) modified polybutylene terephthalate resin, a polybutylene terephthalate resin composition can be obtained that has excellent jet-black properties and low gloss with little gloss unevenness. In addition, the jet-black properties can be further enhanced by adding carbon black.

[0012] (a1) The modified polybutylene terephthalate resin contains terephthalic acid or its ester-forming derivative (C１－６ The copolymer has as its main component polybutylene terephthalate obtained by polycondensation of alkylene glycol (e.g., alkyl ester or acid halide of alkylene glycol having 4 carbon atoms) and alkylene glycol (1,4-butanediol) having 4 carbon atoms or its ester-forming derivative (e.g., acetylated product) as the glycol component, and to which 5 to 30 mol % (preferably 7 to 25 mol %, more preferably 8 to 20 mol %, even more preferably 10 to 15 mol %, e.g., 10 to 13 mol %) of another comonomer component (third component) has been introduced relative to 100 mol % of all dicarboxylic acid components. The other comonomer component (third component) refers to a copolymerizable monomer component different from terephthalic acid or its ester-forming derivative, and 1,4-butanediol or its ester-forming derivative. The content of the comonomer component (third component) in the (a1) modified polybutylene terephthalate resin can be measured, for example, by １ It can be measured using H-NMR.

[0013] Examples of dicarboxylic acid components that can be used as other comonomer components (third components) include C carboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether. ８－１４ aromatic dicarboxylic acids of C, such as succinic acid, adipic acid, azelaic acid, and sebacic acid; ４－１６ alkanedicarboxylic acids such as cyclohexanedicarboxylic acid; ５－１０ cycloalkanedicarboxylic acids of the formula (C); ester-forming derivatives of these dicarboxylic acid components (C １－６ These dicarboxylic acid components may be used alone or in combination of two or more.

[0014] Among these dicarboxylic acid components, C ８－１２ Aromatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid ６－１２ The alkanedicarboxylic acids are more preferred.

[0015] Examples of glycol components that can be used as other comonomer components (third components) include C glycerides such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol. ２－１０ alkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, and the like; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A, and the like; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl, and the like; C-type alkylene glycols of bisphenol A such as ethylene oxide 2-mol adduct of bisphenol A and propylene oxide 3-mol adduct of bisphenol A, and the like; ２－４ or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components may be used alone or in combination of two or more.

[0016] Among these glycol components, C ethylene glycol, trimethylene glycol, etc. ２－６ More preferred are alkylene glycols such as those listed above, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol.

[0017] Examples of the comonomer component (third component) that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C hydroxycarboxylic acids such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); ３－１２ lactones; ester-forming derivatives of these comonomer components (C １－６ alkyl ester derivatives, acid halides, acetylated derivatives, etc.

[0018] Any polybutylene terephthalate copolymer produced by polycondensation of the above compounds as comonomer components can be suitably used as the (a1) modified polybutylene terephthalate resin. In one embodiment, the (a1) modified polybutylene terephthalate resin preferably contains an isophthalic acid-modified polybutylene terephthalate copolymer and / or an alkylene (excluding 1,4-butanediol)-modified polybutylene terephthalate copolymer, and more preferably contains an isophthalic acid-modified polybutylene terephthalate copolymer. The (a1) modified polybutylene terephthalate resin can be used alone or in combination of two or more types.

[0019] The content of the (a1) modified polybutylene terephthalate resin is preferably 80 to 100 mass%, more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, of the total amount (100 mass%) of the (A) polybutylene terephthalate resin. In one embodiment, the (A) polybutylene terephthalate resin may contain only the (a1) modified polybutylene terephthalate resin.

[0020] In one embodiment, the (A) polybutylene terephthalate resin may contain, in addition to the (a1) modified polybutylene terephthalate resin, an (a2) homopolybutylene terephthalate polymer (unmodified polybutylene terephthalate resin). The content of the (a2) homopolybutylene terephthalate polymer may be 0 to 20% by mass, 0 to 10% by mass, or 0 to 5% by mass, based on the total amount (100% by mass) of the (A) polybutylene terephthalate resin.

[0021] From the viewpoint of improving moldability, the intrinsic viscosity of the (A) polybutylene terephthalate resin is preferably 0.65 to 1.15 dL / g, and more preferably 0.67 to 1.00 dL / g. The intrinsic viscosity can also be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL / g can be prepared by blending a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL / g with a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity of the (A) polybutylene terephthalate resin is a value measured in o-chlorophenol at a temperature of 35°C using an Ubbelohde viscometer.

[0022] The amount of terminal carboxyl groups (CEG) of the (A) polybutylene terephthalate resin is not particularly limited as long as it does not impair the object of the present disclosure, but is preferably 5 to 30 meq / kg, more preferably 10 to 25 meq / kg. By using a polybutylene terephthalate resin having a terminal carboxyl group amount in this range, it is possible to suppress a decrease in strength of the resulting polybutylene terephthalate resin composition in a humid and hot environment.

[0023] The content of the (A) polybutylene terephthalate resin is preferably 20 to 60 mass %, more preferably 25 to 50 mass %, and even more preferably 30 to 40 mass %, of the total amount (100 mass %) of the resin composition.

[0024] As described below, the resin composition may contain a thermoplastic resin other than the (A) polybutylene terephthalate resin and the (B) polycarbonate resin. From the viewpoint of easily obtaining a low-gloss polybutylene terephthalate resin composition with excellent jet blackness and little gloss unevenness, the total content of the (A) polybutylene terephthalate resin and the (B) polycarbonate resin is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of the thermoplastic resins forming the resin composition. In one embodiment, the thermoplastic resin contained in the resin composition may contain only the (A) polybutylene terephthalate resin and the (B) polycarbonate resin.

[0025] <(B) Polycarbonate Resin> The resin composition contains a (B) polycarbonate resin. By including the (B) polycarbonate resin, a polybutylene terephthalate resin composition can be obtained that has excellent jet blackness and low gloss with little gloss unevenness. Examples of the (B) polycarbonate resin include polymers obtained by reacting a dihydroxy compound with a carbonate ester such as phosgene or diphenyl carbonate. The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester interchange method) can be used.

[0026] Examples of dihydroxy compounds include alicyclic compounds (for example, alicyclic diols) and bisphenol compounds, with bisphenol compounds being preferred.

[0027] Bisphenol compounds include bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxy-3-methylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)propane ("bisphenol A"), 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3-ethylphenyl)propane, 2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2- Bis(hydroxyaryl) C such as bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)hexane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)dibenzylmethane, 1,1-bis(4-hydroxyphenyl)-1-phenylpropane, and 2,2,2',2'-tetrahydro-3,3,3',3'-tetramethyl-1,1'-spirobi-[1H-indene]-6,6'-diol. １－１０ Alkanes, preferably bis(hydroxyaryl)C １－６ Alkanes; bis(hydroxyaryl) C such as 1,1-bis(4-hydroxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyclohexane; ４－１０cycloalkanes; dihydroxyaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; dihydroxyaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone; dihydroxyaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; dihydroxyaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; and dihydroxyaryl ketones such as 4,4'-dihydroxydiphenyl ketone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ketone.

[0028] A preferred example of the polycarbonate resin (B) is bisphenol A polycarbonate.

[0029] The polycarbonate resin (B) may be a homopolycarbonate or a copolycarbonate. The polycarbonate resins may be used alone or in combination of two or more.

[0030] (B) The melt viscosity of the polycarbonate resin is, from the viewpoint of fluidity, 300°C, 1000 sec in accordance with ISO 11443. －１ The melt viscosity is preferably 0.40 kPa·s or less, more preferably 0.35 kPa·s or less, and even more preferably 0.30 kPa·s or less, using a capillary of 1 mmφ×20 mmL / flat die manufactured by Toyo Seiki Seisakusho Co., Ltd., at a barrel temperature of 300° C. and a shear rate of 1000 sec. －１ The value measured is taken as:

[0031] The content of the (B) polycarbonate resin is 60 to 100 parts by mass, preferably 65 to 95 parts by mass, more preferably 70 to 90 parts by mass, even more preferably 75 to 85 parts by mass, and particularly preferably 75 to 83 parts by mass, per 100 parts by mass of the (A) polybutylene terephthalate resin. By blending a predetermined amount of the (B) polycarbonate resin with the (A) polybutylene terephthalate resin, a polybutylene terephthalate resin composition can be obtained that has excellent jet-black color and low gloss with little gloss unevenness. A non-limiting mechanism is thought to be that blending a predetermined amount of the (B) polycarbonate resin with the (A) polybutylene terephthalate resin can appropriately increase transparency without reducing jet-black color, allowing light incident on the surface of a molded article to be transmitted into the interior of the molded article, where the transmitted light can be absorbed by a light-absorbing material such as (D) carbon black, thereby reducing reflected light on the surface of the molded article.

[0032] In one embodiment, the content of the (B) polycarbonate resin may be 77 parts by mass, 78 parts by mass, 80 parts by mass, 82 parts by mass, or 85 parts by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin, or may be within a range in which these are the upper or lower limit values ​​of the above-mentioned numerical range, or may be a range combining these.

[0033] <(C) Glass Flakes> The resin composition contains (C) glass flakes. The glass flakes have an average thickness of 1 μm or less. The median diameter (D50) of the (C) glass flakes contained in the resin composition is 5 to 70 μm. By containing (C) glass flakes having an average thickness of 1 μm or less and a median diameter of 5 to 70 μm, a polybutylene terephthalate resin composition can be obtained that has excellent jet-black color and low gloss with little gloss unevenness.

[0034] The average thickness of the (C) glass flakes is preferably 1 μm or less, more preferably 0.9 μm or less, even more preferably 0.8 μm or less, and particularly preferably 0.7 μm or less. In one embodiment, the average thickness of the (C) glass flakes may be 0.01 to 1 μm, 0.05 to 1 μm (e.g., 0.05 to 0.9 μm, 0.05 to 0.8 μm, or 0.05 to 0.7 μm), or 0.1 to 1 μm (e.g., 0.1 to 0.9 μm, 0.1 to 0.8 μm, 0.1 to 0.7 μm, 0.7 to 1 μm, or 0.7 to 0.9 μm). The average thickness of the (C) glass flakes may be a value provided by the raw material manufacturer or calculated by measurement. For example, images taken with a CCD camera using a 2-propanol solvent are analyzed using a dynamic image analysis / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd., and the weighted average can be calculated. Alternatively, the average value may be determined by direct observation using an electron microscope, etc. The average thickness of the (C) glass flakes in the experimental data is a value measured by the above method for the (C) glass flakes in the resin composition.

[0035] The median diameter (D50) of the (C) glass flakes contained in the resin composition is 5 to 70 μm, preferably 10 to 60 μm, more preferably 20 to 50 μm, even more preferably 30 to 48 μm, and particularly preferably 35 to 45 μm. In one embodiment, the median diameter of the (C) glass flakes may be 40 μm or 41 μm, or may be within the upper or lower limit of the above-mentioned numerical range. In the present disclosure, the median diameter is the median diameter of the (C) glass flakes in the resin composition measured by a laser diffraction / scattering method (e.g., LA-960 manufactured by Horiba, Ltd.). The median diameter of the (C) glass flakes in the resin composition can be measured by treating the resin composition or a molded product thereof in an electric furnace at 600°C for 4 hours, and then measuring the remaining residue by the laser diffraction / scattering method.

[0036] In one embodiment, the average thickness of the (C) glass flakes may be 1 μm or less, and the median diameter (D50) of the (C) glass flakes may be 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 20 to 50 μm, and particularly preferably 35 to 45 μm. In one embodiment, the average thickness of the (C) glass flakes may be 0.01 to 1 μm, and the median diameter (D50) of the (C) glass flakes may be 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 20 to 50 μm, and particularly preferably 35 to 45 μm. In one embodiment, the average thickness of the (C) glass flakes may be 0.05 to 1 μm, and the median diameter (D50) of the (C) glass flakes may be 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 20 to 50 μm, and particularly preferably 35 to 45 μm. In one embodiment, the average thickness of the (C) glass flakes may be 0.1 to 1 μm, and the median diameter (D50) of the (C) glass flakes may be 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 20 to 50 μm, and particularly preferably 35 to 45 μm. In one embodiment, the average thickness of the (C) glass flakes may be 0.7 μm or less, and the median diameter (D50) of the (C) glass flakes may be 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 20 to 50 μm, and particularly preferably 35 to 45 μm.

[0037] The average aspect ratio of the (C) glass flakes is not limited as long as it does not impair the effects of the present disclosure, and is preferably 5 to 200, more preferably 20 to 150, and even more preferably 30 to 100. The average aspect ratio is used here as an index representing the anisotropy of the plate shape, and is the ratio of the median diameter to the average thickness (aspect ratio = median diameter / average thickness). The median diameter can be measured by a laser diffraction / scattering method (LA-960 manufactured by Horiba, Ltd.) or the like. Alternatively, the ratio of particle size to thickness may be calculated by direct observation using an electron microscope or the like, and the average values ​​thereof may be determined. The median diameter and aspect ratio of the (C) glass flakes are values ​​measured by the above-mentioned method for the (C) glass flakes remaining as residue after treating a molded article made of a resin composition in an electric furnace at 600°C for 4 hours.

[0038] The content of the (C) glass flakes is 60 to 100 parts by mass, preferably 65 to 95 parts by mass, more preferably 70 to 90 parts by mass, even more preferably 75 to 85 parts by mass, and particularly preferably 75 to 83 parts by mass, relative to 100 parts by mass of the (A) polybutylene terephthalate resin. By blending a predetermined amount of (C) glass flakes having a predetermined thickness and a predetermined median diameter in the resin composition with the (A) polybutylene terephthalate resin, a polybutylene terephthalate resin composition can be obtained that has excellent jet-black color and low gloss with little gloss unevenness. A non-limiting mechanism is thought to be that thin-walled (C) glass flakes having a predetermined thickness and median diameter tend to break into an amorphous shape during molding, forming an irregular surface, and blending them in a predetermined amount tends to roughen the surface of the molded article into a matte finish with fine irregularities, resulting in random reflection of light. When light is reflected randomly, the reflected light is repeatedly taken in and absorbed inside the molded product, thereby attenuating it, which is thought to achieve a low gloss with little gloss unevenness without reducing the jet black color.

[0039] In one embodiment, the content of the (C) glass flakes may be 77 parts by mass, 78 parts by mass, 80 parts by mass, 81 parts by mass, or 85 parts by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin, or may be within a range in which these are the upper or lower limit values ​​of the above-mentioned numerical range, or may be a range that combines these.

[0040] As described below, the resin composition may contain fillers other than the (C) glass flakes, but from the viewpoint of easily obtaining a polybutylene terephthalate resin composition having excellent jet blackness and low gloss with little gloss unevenness, the content of the (C) glass flakes is preferably 80 to 100 mass %, more preferably 85 to 100 mass %, even more preferably 90 to 100 mass %, and particularly preferably 95 to 100 mass % of the total amount (100 mass %) of the inorganic fillers contained in the resin composition. In one embodiment, the inorganic filler contained in the resin composition may contain only the (C) glass flakes.

[0041] <(D) Carbon Black> The resin composition contains (D) carbon black. Examples of (D) carbon black include furnace black, ketjen black, channel black, acetylene black, and thermal black. (D) carbon black can be used alone or in combination of two or more. (D) carbon black may be used as a pigment (or colorant).

[0042] (D) The dibutyl phthalate (DBP) oil absorption of carbon black is 30 to 600 cm from the viewpoint of blackness and light absorption. ３ / 100g is preferred, and 40 to 550cm ３ / 100g is more preferable, 50 to 500cm ３ In one embodiment, the DBP oil supply amount of the carbon black (D) is 40 to 100 cm ３ / 100g (for example, 50-80cm ３ / 100g), and 100cm ３ / Over 100g 500cm ３ / 100g or less (for example, 100 to 495cm ３ The dibutyl phthalate oil absorption is a value measured in accordance with JIS K6217-4:2008.

[0043] The average particle size of the (D) carbon black is preferably 5 to 100 nm, more preferably 8 to 50 nm, and even more preferably 10 to 40 nm. In one embodiment, the average particle size of the (D) carbon black is preferably 8 to 30 nm, more preferably 10 to 30 nm, from the viewpoint of further enhancing the jet blackness of the molded article and easily providing a molded article with high light absorption. In one embodiment, the average particle size of the (D) carbon black may be 13 nm, 16 nm, 22 nm, or 34 nm, or may be within the range defined by the upper or lower limit of the above numerical range, or may be a combination of these ranges. The average particle size is the arithmetic mean particle size determined by electron microscopy of 1,000 randomly selected particles of carbon black before being blended into the resin composition.

[0044] The content of (D) carbon black is 0.8 to 15 parts by mass (e.g., 0.9 to 15 parts by mass or 1 to 15 parts by mass) and preferably 0.8 to 12 parts by mass (e.g., 0.9 to 12 parts by mass or 1 to 12 parts by mass) relative to 100 parts by mass of the (A) polybutylene terephthalate resin. By including (D) carbon black in an amount of 0.8 to 15 parts by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin, a polybutylene terephthalate resin composition can be obtained that has excellent jet blackness and low gloss with little gloss unevenness. From the viewpoint of easily obtaining a polybutylene terephthalate resin composition having better jet blackness, less gloss unevenness, and better low gloss, the content of (D) carbon black is more preferably 0.8 to 11 parts by mass (e.g., 0.9 to 11 parts by mass, 1 to 11 parts by mass), more preferably 0.8 to 10 parts by mass, even more preferably 0.8 to 8 parts by mass, or even 1 to 6 parts by mass, relative to 100 parts by mass of the (A) polybutylene terephthalate resin. In one embodiment, the content of (D) carbon black may be 1.3 parts by mass, 2.6 parts by mass, or 5.3 parts by mass, relative to 100 parts by mass of the (A) polybutylene terephthalate resin, or may be within the range defined by the upper or lower limit of the above-mentioned numerical range, or may be within a combination of these ranges.

[0045] In one embodiment, the polybutylene terephthalate resin composition may be such that, relative to 100 parts by mass of the (A) polybutylene terephthalate resin, the content of the (B) polycarbonate resin is 60 to 100 parts by mass, preferably 65 to 95 parts by mass, more preferably 70 to 90 parts by mass, even more preferably 75 to 85 parts by mass, and particularly preferably 75 to 83 parts by mass; the content of the (C) glass flakes is 60 to 100 parts by mass, preferably 65 to 95 parts by mass, more preferably 70 to 90 parts by mass, even more preferably 75 to 85 parts by mass, and particularly preferably 75 to 83 parts by mass; and the content of the (D) carbon black is 0.8 to 15 parts by mass, preferably 0.8 to 12 parts by mass, more preferably 0.8 to 11 parts by mass, even more preferably 0.8 to 10 parts by mass, particularly preferably 0.8 to 8 parts by mass, and most preferably 1 to 6 parts by mass. In all embodiments, the respective numerical ranges of the content of the (B) polycarbonate resin, the content of the (C) glass flakes, and the content of the (D) carbon black relative to 100 parts by mass of the (A) polybutylene terephthalate resin may be combined.

[0046] <(F) Phosphorus-Based Compound> The resin composition may contain a (F) phosphorus-based compound as needed. By containing a (F) phosphorus-based compound, it is possible to improve the mold releasability during injection molding and the heat resistance of the molded article.

[0047] Examples of phosphorus-based compounds include organic phosphite compounds, organic phosphonite compounds, alkali metal phosphates, and alkaline earth metal phosphates. Examples of organic phosphite compounds include bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and bis(nonylphenyl)pentaerythritol diphosphite. Examples of organic phosphonite compounds include tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphonite. Examples of alkali metal phosphates include alkali metal salts such as potassium phosphate and sodium phosphate [monosodium phosphate (sodium dihydrogen phosphate), disodium phosphate (sodium hydrogen phosphate, sodium monohydrogen phosphate, disodium hydrogen phosphate)]. Examples of alkaline earth metal phosphates include alkaline earth metal salts such as calcium phosphate [monocalcium phosphate (calcium dihydrogen phosphate, calcium bis(dihydrogen phosphate) monohydrate, etc.], dibasic calcium phosphate (calcium hydrogen phosphate, calcium hydrogen phosphate dihydrate, etc.)], and magnesium phosphate (magnesium hydrogen phosphate, magnesium dihydrogen phosphate, etc.). The alkali metal salt or alkaline earth metal salt may be either anhydrous or hydrated. The (F) phosphorus-based compound may be used alone or in combination of two or more.

[0048] Of these phosphorus compounds, one or more selected from alkali metal phosphates, alkaline earth metal phosphates, and organic phosphites are preferred.

[0049] The content of the (F) phosphorus-based compound is preferably 0.01 to 2.0 parts by mass, and more preferably 0.05 to 1.0 part by mass, per 100 parts by mass of the (A) polybutylene terephthalate resin.

[0050] (Other Resin Components) The resin composition may contain other thermoplastic resins other than (A) polybutylene terephthalate resin and (B) polycarbonate resin, as long as the effects of the present disclosure are not impaired. Examples of other thermoplastic resins include polyethylene terephthalate and acrylonitrile styrene resin. The content of the other thermoplastic resin is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, and may be 0 to 5 parts by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin.

[0051] The resin composition may contain an elastomer (e.g., ABS, core-shell elastomer, etc.) generally used to improve impact resistance. However, since a large difference in refractive index between the elastomer and polybutylene terephthalate or polycarbonate can easily cause whitening, the refractive index of the elastomer is preferably about 1.55 to 1.60 in order to further enhance the jet-blackness of the molded product. For example, a core-shell elastomer with a particle size of about 1 to 10 μm has the effect of reducing gloss, but the acrylic resin used in the shell, etc., has a low refractive index and is prone to whitening. Therefore, the content of the core-shell elastomer is preferably less than 2% by mass, and more preferably less than 1% by mass, of the total amount (100% by mass) of the resin composition.

[0052] (Other Fillers) The resin composition may contain fillers other than (C) glass flakes, as necessary. As the filler, a fibrous filler, a powdery filler (excluding carbon black), and a plate-like filler (excluding glass flakes) can be used depending on the purpose. The content of the other filler is preferably 0 to 60 parts by mass, preferably 0 to 50 parts by mass, preferably 0 to 30 parts by mass, or may be 0 to 20 parts by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin.

[0053] In one embodiment, from the viewpoint of easily realizing a low-gloss polybutylene terephthalate resin composition, the content of the glass fiber in the resin composition is preferably less than 20 parts by mass, more preferably less than 10 parts by mass, even more preferably less than 5 parts by mass, and particularly preferably less than 1 part by mass, relative to 100 parts by mass of the polybutylene terephthalate resin (A).

[0054] (Additives) In addition to the above components, the resin composition may contain known additives that are generally added to thermoplastic resins and thermosetting resins, i.e., burr inhibitors, release agents, lubricants (e.g., fatty acid esters, etc.), plasticizers, flame retardants, colorants such as dyes and pigments (excluding carbon black), crystallization accelerators, crystal nucleating agents (e.g., boron nitride, etc.), various antioxidants, heat stabilizers, weather resistance stabilizers, corrosion inhibitors, etc., within the scope of not impairing the effects of the present disclosure.

[0055] The method for preparing the resin composition is not limited, and examples thereof include a method in which each component is melt-kneaded and extruded into pellets using a melt-kneading device such as a single-screw or twin-screw extruder, a method in which pellets (master batches) having different compositions are prepared and then a predetermined amount of the pellets is mixed, etc. The pellets may be prepared, for example, by melt-mixing components other than a brittle component (such as glass flakes) and then mixing the brittle component.

[0056] The resin composition has excellent low gloss and little gloss unevenness. In one embodiment, the resin composition has a molded article having a 60° gloss according to JIS-Z-8741 of preferably 27 or less, more preferably 23 or less. In one embodiment, the resin composition has a molded article having a 60° gloss according to JIS-Z-8741:1997 of preferably 27 or less, more preferably 23 or less, when injection molded at an injection speed of 30 mm / s, 80 mm / s, or 120 mm / s. The gloss can be measured at an angle of 60° using a gloss meter (for example, a Handy Gloss Meter PG-II manufactured by Nippon Denshoku Industries Co., Ltd.).

[0057] In one embodiment, the resin composition has excellent jet-black properties. In one embodiment, the resin composition has a molded article having an L* value of preferably 14 or less, more preferably 13 or less, as measured in accordance with JIS-Z-8781-4:2013. Because of its excellent jet-black properties, it is possible to absorb light and prevent reflection. In one embodiment, the resin composition has a molded article having an L* value of preferably 14 or less, more preferably 13 or less, as measured at three arbitrarily selected locations on the molded article by the above method.

[0058] (Applications) The resin composition of the present disclosure has excellent jet-black color and low gloss with little uneven gloss, and therefore can be preferably used for manufacturing components for various optical devices and display devices, such as drive recorders, backup cameras, ADAS, head-up displays, liquid crystal meters, and car navigation systems.

[0059] [Molded Article] The molded article contains the polybutylene terephthalate resin composition described above. Because the molded article contains the polybutylene terephthalate resin composition described above, it has excellent jet blackness and low gloss, and has little gloss unevenness depending on the part of the molded article.

[0060] In one embodiment, the molded article has a 60° gloss according to JIS-Z-8741 of preferably 27 or less, more preferably 23 or less. In one embodiment, the molded article has a 60° gloss measured by the above method at three arbitrarily selected points of preferably 27 or less, more preferably 23 or less.

[0061] In one embodiment, the molded article preferably has an L* value in accordance with JIS-Z-8781-4 of 14 or less, more preferably 13 or less. In one embodiment, the molded article preferably has an L* value measured by the above method at three arbitrarily selected locations of 14 or less, more preferably 13 or less.

[0062] The molded article may have a surface textured to further enhance its low gloss properties, but the inclusion of the resin composition provides excellent low gloss properties and little gloss unevenness, so the surface does not need to be textured. The molded article may have a surface coated with a matting agent to further enhance its low gloss properties, but the inclusion of the resin composition provides excellent low gloss properties and little gloss unevenness, so the surface does not need to be coated with a matting agent. Examples of matting agents include acrylic, urethane, and epoxy paints.

[0063] The molding method for the molded article is not limited, and may be a conventional method such as extrusion molding, injection molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc., but is usually injection molding. The mold temperature during injection molding is usually about 40 to 120°C, preferably 50 to 80°C, and more preferably about 60 to 80°C.

[0064] The present disclosure will be explained in more detail below by showing examples, but interpretation of the present disclosure is not limited to these examples.

[0065] <Materials> A-1: ​​Polybutylene terephthalate resin (manufactured by Polyplastics Co., Ltd., intrinsic viscosity (IV) 0.69 dL / g, terminal carboxyl group amount (CEG) 16 meq / kg) A-2: Isophthalic acid modified polybutylene terephthalate resin (manufactured by Polyplastics Co., Ltd., isophthalic acid 12.5 mol% modified polybutylene terephthalate resin) B: Polycarbonate resin (manufactured by Teijin Limited, Panlite L-1225L), melt viscosity (300°, 1000 sec) －１) 0.27 kPa s C-1: Glass flakes (manufactured by Nippon Sheet Glass Co., Ltd., Fine Flake MEG160FY-M01), average thickness 0.7 μm, average particle diameter 160 μm (manufacturer's catalog value) C-2: Glass flakes (manufactured by Nippon Sheet Glass Co., Ltd., REFG-108), average thickness 5 μm, average particle diameter 600 μm (manufacturer's catalog value) C-3: Potassium titanate (manufactured by Otsuka Chemical Co., Ltd., Tismo N102) C-4: Talc (manufactured by Hayashi Kasei Co., Ltd., Micron White Upn HS-T0.8), average particle diameter 2.7 μm C-5: Talc (manufactured by Matsumura Sangyo Co., Ltd., Crown Talc ID), average particle diameter 19 μm D-1: Ketjen black (manufactured by Lion Specialty Chemicals Co., Ltd., EC600JD), average particle diameter 34 nm, DBP absorption amount 495 cm ３ / 100g D-2: Carbon black (Mitsubishi Chemical Corporation, Carbon Black #750B), average particle size 22 nm, DBP absorption 116 cm ３ / 100g D-3: Carbon black (Mitsubishi Chemical Corporation, Carbon Black #960B), average particle size 16 nm, DBP absorption 69 cm ３ / 100g D-4: Carbon black (Mitsubishi Chemical Corporation, Carbon Black #2600), average particle size 13 nm, DBP absorption 77 cm ３ / 100g E-1: Core-shell elastomer (Kane Ace MP90, manufactured by Kaneka Corporation) E-2: Core-shell elastomer (Staphyloid PO-0935, manufactured by Aica Kogyo Co., Ltd.) F: Monocalcium phosphate (Taihei Chemical Industry Co., Ltd., transesterification inhibitor) G: Boron nitride (Mizushima Ferroalloy Co., Ltd., nucleating agent) H: Fatty acid ester (Rikemal B-150, lubricant, manufactured by Riken Vitamin Co., Ltd.)

[0066] [Examples 1 to 10, Comparative Examples 1 to 21] Raw materials were mixed in the proportions shown in Tables 1 and 2, and the mixture was melt-kneaded and extruded using a twin-screw extruder at a cylinder temperature of 260°C and a screw rotation of 150 rpm to produce polybutylene terephthalate resin compositions of Examples 1 to 10 and Comparative Examples 1 to 21. Three plate-shaped molded products (dimensions: 70 mm x 50 mm x 3 mm thick) were molded using the obtained polybutylene terephthalate resin compositions at a cylinder temperature of 260°C, a mold temperature of 80°C, a holding pressure of 60 MPa, and injection speeds of 30 mm / s, 80 mm / s, and 120 mm / s.

[0067] [Measurement and Evaluation] The 60° gloss and lightness L* of each of the obtained molded articles were measured by the following methods. The results are shown in Tables 1 and 2.

[0068] <60° Gloss> Gloss (%) was measured in accordance with JIS-Z-8741:1997 using a handy gloss meter PG-II (60°) manufactured by Nippon Denshoku Industries Co., Ltd. Low gloss and gloss unevenness were evaluated based on the following criteria. (Low gloss) 3: All gloss values ​​of three molded products with different injection speeds were 23% or less (excellent low gloss and little gloss unevenness) 2: All gloss values ​​of three molded products with different injection speeds were 27% or less (good low gloss) 1: One or more gloss values ​​of three molded products with different injection speeds exceeded 27% (poor low gloss (high gloss)) (Gloss unevenness) 3: The difference between the maximum and minimum gloss values ​​of three molded products with different injection speeds was 5 or less 2: The difference between the maximum and minimum gloss values ​​of three molded products with different injection speeds was more than 5 but not more than 10 1: The difference between the maximum and minimum gloss values ​​of three molded products with different injection speeds exceeded 10

[0069] (Lightness L*) The L* value was measured in accordance with JIS-Z-8781-4:2013 using an SM-P color computer manufactured by Suga Test Instruments Co., Ltd. The jet-blackness was evaluated based on the following criteria: 3: All L* values ​​of three molded products with different injection speeds were 13 or less (excellent jet-blackness) 2: All L* values ​​of three molded products with different injection speeds were greater than 13 and less than 14 (good jet-blackness) 1: The L* value of one or more of the three molded products with different injection speeds was greater than 14

[0070] (Median diameter of glass flakes) A ​​molded article made of a polybutylene terephthalate resin composition (among the above molded articles, a molded article molded at an injection speed of 80 mm / s) was treated in an electric furnace at 600°C for 4 hours, and the median diameter of the glass flakes was calculated from the remaining residue using a laser diffraction / scattering particle size distribution analyzer LA-960 manufactured by Horiba, Ltd.

[0071]

[0072] As shown in Table 1, the resin compositions of Examples 1 to 10 can give molded articles with excellent jet blackness and low gloss with little uneven gloss.

[0073] INDUSTRIAL APPLICABILITY The resin composition of the present disclosure has excellent jet-black color and low gloss with little uneven gloss, and therefore can be preferably used for producing various optical device components and display device components, and has industrial applicability.

Claims

1. A polybutylene terephthalate resin composition comprising: (A) a polybutylene terephthalate resin; (B) a polycarbonate resin; (C) glass flakes; and (D) carbon black; (A) the polybutylene terephthalate resin comprises (a1) a modified polybutylene terephthalate resin containing 5 to 30 mol% of a comonomer unit; (C) the glass flakes have an average thickness of 1 μm or less and a median diameter of 5 to 70 μm; (B) the polycarbonate resin is contained in an amount of 60 to 100 parts by mass relative to 100 parts by mass of the polybutylene terephthalate resin; (C) the glass flakes are contained in an amount of 60 to 100 parts by mass; and (D) the carbon black is contained in an amount of 0.8 to 15 parts by mass.

2. The polybutylene terephthalate resin composition according to claim 1, further comprising (F) a phosphorus-based compound.

3. A molded article comprising the resin composition according to claim 1 or 2.

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