Polybutylene terephthalate resin composition

Abstract

To provide a polybutylene terephthalate resin composition which is excellent in jet-blackness, is reduced in gloss unevenness and has low glossiness.SOLUTION: A polybutylene terephthalate resin composition contains (A) a polybutylene terephthalate resin, (B) a polycarbonate resin, (C) a glass flake, and (D) carbon black, wherein (A) the polybutylene terephthalate resin contains (a1) a modified polybutylene terephthalate resin containing 5 to 30 mol% of a comonomer unit, (C) the glass flake has average thickness of 1 μm or less and a median size of 5 to 70 μm or less, and with respect to 100 pts.mass of (A) the polybutylene terephthalate resin, a content of (B) the polycarbonate resin is 60 to 100 pts.mass, a content of (C) the glass flake is 60 to 100 pts.mass, and a content of (D) the carbon black is 0.8 to 15 pts.mass.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Members of optical devices such as drive recorders, rear cameras, and ADAS mounted on vehicles such as automobiles, and members of display devices such as head-up displays, liquid crystal meters, and car navigation systems are required to have low glossiness in order to reduce reflections and other glare. Since many plastic materials form a high-gloss surface when molded, a mold for injection molding is provided with a texture to apply a texture process to the surface of the molded product, or a matting agent is applied to the surface of the molded product to achieve low glossiness. As attempts to achieve low glossiness based on the characteristics of the material itself, there are, for example, Patent Documents 1 and 2.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0005] The present disclosure includes the following aspects. [1] (A) A polybutylene terephthalate resin, (B) A polycarbonate resin, (C) Glass flakes, and (D) Carbon black, (A) The polybutylene terephthalate resin contains a modified polybutylene terephthalate resin containing (a1) 5 to 30 mol% of comonomer units, (C) The average thickness of the glass flakes is 1 μm or less and the median diameter is 5 to 70 μm, (A) Based on 100 parts by mass of the polybutylene terephthalate resin, (B) The content of the polycarbonate resin is 60 to 100 parts by mass, (C) The content of the glass flakes is 60 to 100 parts by mass, (D) The content of carbon black is 0.8 to 15 parts by mass, a polybutylene terephthalate resin composition. [2] The polybutylene terephthalate resin composition according to [1], further containing (F) a phosphorus-based compound. [3] A molded article containing the resin composition according to [1] or [2]. [Effect of the Invention]

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

[0007] Hereinafter, an embodiment of the present disclosure will be described in detail. 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. Further, when a plurality of upper limit values and lower limit values are described for a specific parameter, any upper limit value and lower limit value can be combined to form a suitable numerical range. Further, the lower limit value and / or upper limit value of the numerical range described in the present disclosure can be replaced with a numerical value within that numerical range and shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less". When a specific description given for one embodiment also applies to other embodiments, the description may be omitted in other embodiments. Each configuration and their combinations in each embodiment are examples, and within the scope not departing from the gist of the present disclosure, addition, omission, substitution, and other changes of the configuration can be made as appropriate.

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

[0009] When light is incident on the surface of a molded article, reflection, transmission, and absorption phenomena of light occur. From the viewpoint of enhancing light absorption and reducing light reflection on the surface of the molded article, it is preferable that the resin composition has excellent blackness. Conventionally, black coloring has been performed by blending carbon black into the resin composition. However, depending on the composition of the resin composition, sufficient blackness may not be obtained even when carbon black is blended. In addition, when there is a large amount of reflected light on the surface of the molded article, the glossiness increases, so it is preferable to reduce the reflected light. By increasing the light transmittance of the resin material, it is expected that light will be taken into the interior of the molded article and the reflected light will decrease. However, if the light transmittance is too high, the glossiness may increase or the blackness may decrease. Furthermore, when the injection speed changes during injection molding of the resin composition, uneven gloss may occur in the obtained molded article. In particular, for a molded article having a complex shape, even when multi-stage speed control is performed, the resin filling speed varies depending on the location of the molded article, so uneven gloss may occur in the obtained molded article. By having the above configuration, the resin composition of the present disclosure can achieve both excellent blackness and low glossiness, and can provide a molded article with little gloss unevenness.

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

[0011] <(A) Polybutylene terephthalate resin> (A) The polybutylene terephthalate resin contains (a1) a modified polybutylene terephthalate resin containing 5 to 30 mol% of comonomer units (hereinafter, also simply referred to as "(a1) modified polybutylene terephthalate resin"). By containing the (a1) modified polybutylene terephthalate resin, it is possible to obtain a polybutylene terephthalate resin composition having excellent blackness and low glossiness with little gloss unevenness. In addition, the blackness by blending carbon black can be further enhanced.

[0012] (a1) The modified polybutylene terephthalate resin is mainly composed of polybutylene terephthalate obtained by polycondensation reaction of terephthalic acid or its ester-forming derivative (such as alkyl ester or acid halide of C 1-6 ) as the dicarboxylic acid component and alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (such as acetylated product) as the glycol component. To this, based on 100 mol% of the total dicarboxylic acid component, another comonomer component (third component) is introduced in an amount of 5 to 30 mol% (preferably 7 to 25 mol%, more preferably 8 to 20 mol%, still more preferably 10 to 15 mol%, for example, 10 to 13 mol%). The other comonomer component (third component) means a copolymerizable monomer component different from terephthalic acid or its ester-forming derivative and 1,4-butanediol or its ester-forming derivative. The measurement of the content of the comonomer component (third component) in the (a1) modified polybutylene terephthalate resin can be carried out, for example, 1 by using 1H-NMR.

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

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

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

[0016] Among these glycol components, alkylene glycols such as ethylene glycol, trimethylene glycol, etc. C 2-6 of alkylene glycol, polyoxyalkylene glycols such as diethylene glycol, or alicyclic diols such as cyclohexanedimethanol are more preferable.

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

[0018] The polybutylene terephthalate copolymers produced by polycondensing the above compounds as comonomer components can all be suitably used as (a1) modified polybutylene terephthalate resins. 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.

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

[0021] (A) The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.65 to 1.15 dL / g, more preferably 0.67 to 1.00 dL / g, from the viewpoint of improving moldability. It is also possible to blend polybutylene terephthalate resins having different intrinsic viscosities to adjust the intrinsic viscosity. 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 and a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity of the (A) polybutylene terephthalate resin is the value measured in o-chlorophenol at a temperature of 35 °C using an Ubbelohde viscometer.

[0022] (A) The amount of terminal carboxyl groups (CEG) of the polybutylene terephthalate resin is not particularly limited as long as it does not inhibit 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 an amount of terminal carboxyl groups within such a range, it is possible to suppress a decrease in strength of the obtained polybutylene terephthalate resin composition in a wet heat environment.

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

[0024] The resin composition may contain, as will be described later, a thermoplastic resin other than (A) polybutylene terephthalate resin and (B) polycarbonate resin. However, from the viewpoint of easily obtaining a low gloss polybutylene terephthalate resin composition having excellent blackness and little gloss unevenness, the total content of (A) polybutylene terephthalate resin and (B) polycarbonate resin is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, still more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass in the total amount (100% by mass) of the thermoplastic resins constituting the resin composition. In one embodiment, the thermoplastic resin contained in the resin composition may be composed of only (A) polybutylene terephthalate resin and (B) polycarbonate resin.

[0025] <(B) polycarbonate resin> The resin composition contains (B) polycarbonate resin. By containing (B) polycarbonate resin, a low gloss polybutylene terephthalate resin composition having excellent blackness and little gloss unevenness can be obtained. Examples of the (B) polycarbonate resin include polymers obtained by the reaction of a dihydroxy compound and a carbonate ester such as phosgene or diphenyl carbonate. The method for producing the polycarbonate resin is not particularly limited, and those produced by a conventionally known phosgene method (interfacial polymerization method) or melting method (transesterification method) can be used.

[0026] Examples of the dihydroxy compound include alicyclic compounds (for example, alicyclic diols) and bisphenol compounds, and bisphenol compounds are preferred.

[0027] Examples of the bisphenol compound 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(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, 2,2,2’,2’-tetrahydro3,3,3’,3’-tetramethyl-1,1’-spirobi-[1H-indene]-6,6’-diol, and other bis(hydroxyaryl)C 1-10 alkane, preferably bis(hydroxyaryl)C 1-6 alkane; 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and other bis(hydroxyaryl)C 4-10Cycloalkanes; dihydroxyaryl ethers such as 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; dihydroxyaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone; dihydroxyaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; dihydroxyaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; dihydroxyaryl ketones such as 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ketone, etc. may be mentioned.

[0028] Preferred (B) polycarbonate resins include bisphenol A type polycarbonates.

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

[0030] (B) From the viewpoint of fluidity, the melt viscosity of the polycarbonate resin 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, as the melt viscosity at 300 °C and 1000 sec -1 in accordance with ISO11443. The melt viscosity is measured using a Capillograph manufactured by Toyo Seiki Seisakusho, using a 1 mmφ×20 mmL / flat die as the capillary, a barrel temperature of 300 °C, and a shear rate of 1000 sec -1 and is the value measured under these conditions.

[0031] (B) The content of the polycarbonate resin is 60 to 100 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, preferably 65 to 95 parts by mass, more preferably 70 to 90 parts by mass, still more preferably 75 to 85 parts by mass, and particularly preferably 75 to 83 parts by mass. By blending a predetermined amount of the (B) polycarbonate resin with the (A) polybutylene terephthalate resin, a low gloss polybutylene terephthalate resin composition excellent in blackness and having little gloss unevenness can be obtained. As a non-limiting mechanism, by blending a predetermined amount of the (B) polycarbonate resin with the (A) polybutylene terephthalate resin, the transparency can be moderately increased, and the light incident on the surface of the molded product can be transmitted into the interior of the molded product without reducing the blackness, and the transmitted light can be absorbed by a light absorber such as (D) carbon black, so that the reflected light on the surface of the molded product can be reduced.

[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, 85 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, and these may be in the range of taking the upper limit value or the lower limit value of the above numerical range, or these may be in a combined range.

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

[0034] (C) The average thickness of the glass flakes is preferably 0.9 μm or less, more preferably 0.8 μm or less, and may be 0.7 μm or less. In one embodiment, the average thickness of the (C) glass flakes may be 0.01 to 1 μm, may be 0.05 to 1 μm (for example, 0.05 to 0.9 μm, 0.05 to 0.8 μm, or 0.05 to 0.7 μm), or may be 0.1 to 1 (for example, 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). (C) The average thickness of the glass flakes may be the value provided by the raw material manufacturer or may be measured and calculated. For example, for those manufactured by Seishin Enterprise Co., Ltd., an image taken with a CCD camera using a 2-propanol solvent can be analyzed by a dynamic image analysis method / particle (state) analyzer PITA-3, etc., and calculated by weighted average. Also, the average value may be obtained by direct observation using an electron microscope or the like. The average thickness of the (C) glass flakes in the experimental data is the 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, and more preferably 20 to 50 μm. In one embodiment, the median diameter of the (C) glass flakes may be 40 μm, may be 41 μm, or may be in a range with these as the upper limit value or lower limit value of the above numerical range. In the present disclosure, the median diameter is the median diameter measured by the laser diffraction / scattering method (for example, LA-960 manufactured by Horiba, Ltd.) for the (C) glass flakes in the resin composition. The median diameter of the (C) glass flakes in the resin composition can be measured by the laser diffraction / scattering method for the residue remaining after treating the resin composition or its molded article in an electric furnace at 600 °C for 4 hours.

[0036] (C) The average aspect ratio of the glass flakes is not limited as long as it does not inhibit the effects of the present disclosure, and is preferably 5 to 200, more preferably 20 to 150, and even more preferably 30 to 100. Here, the average aspect ratio is used 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 the particle diameter to the thickness may be calculated by direct observation using an electron microscope or the like, and the average value thereof may be obtained respectively. The median diameter and aspect ratio of the (C) glass flakes are values measured by the above method for the (C) glass flakes remaining as a residue after treating a molded product made of the resin composition in an electric furnace at 600 °C for 4 hours.

[0037] (C) The content of the 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 with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. By blending a (C) glass flake having a predetermined thickness and a predetermined median diameter in the resin composition into the (A) polybutylene terephthalate resin in a predetermined amount, a low gloss polybutylene terephthalate resin composition excellent in blackness and having little gloss unevenness can be obtained. As a non-limiting mechanism, the thin (C) glass flakes having a predetermined thickness and median diameter are likely to break into an amorphous state during molding to form a surface without regularity, and by blending them in a predetermined amount, the surface of the molded product is likely to be roughened into a satin finish having fine irregularities, so that light is reflected randomly. When light is reflected randomly, the reflected light is repeatedly taken into or absorbed by the inside of the molded product and attenuated, whereby it is considered that low gloss with little gloss unevenness can be realized without reducing blackness.

[0038] In one embodiment, the content of (C) glass flakes may be 77 parts by mass, 78 parts by mass, 80 parts by mass, 81 parts by mass, 85 parts by mass, or any value within the range defined by these upper and lower limits, or any combination thereof, based on 100 parts by mass of (A) polybutylene terephthalate resin.

[0039] As described later, the resin composition may contain fillers other than (C) glass flakes. However, from the perspective of easily obtaining a low-gloss polybutylene terephthalate resin composition with excellent blackness and less gloss unevenness, the content of (C) glass flakes is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, still more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of inorganic fillers contained in the resin composition. In one embodiment, the inorganic filler contained in the resin composition may be composed of only (C) glass flakes.

[0040] <(D) Carbon black> The resin composition contains (D) carbon black. Examples of (D) carbon black include furnace black, ketjen black, channel black, acetylene black, thermal black, etc. (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).

[0041] (D) The dibutyl phthalate (DBP) oil absorption of carbon black is preferably 30 to 600 cm 3 / 100 g from the viewpoints of blackness and light absorption, more preferably 40 to 550 cm 3 / 100 g, and still more preferably 50 to 500 cm 3 / 100 g. In one embodiment, the DBP oil absorption of (D) carbon black is 40 to 100 cm 3 / 100 g (for example, 50 to 80 cm 3 / 100 g) and may also be 100 cm3 exceeding 500 cm / 100 g 3 not exceeding 500 cm / 100 g (for example, 100 to 495 cm 3 / 100 g) may be used. The dibutyl phthalate oil absorption amount shall be the value measured in accordance with JIS K6217-4:2008.

[0042] (D) The average particle diameter of 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, from the viewpoint of further enhancing the jet blackness of the molded product and easily providing a molded product with high light absorption, the average particle diameter of (D) carbon black is preferably 8 to 30 nm, and more preferably 10 to 30 nm. In one embodiment, the average particle diameter of (D) carbon black may be 13 nm, may be 16 nm, may be 22 nm, may be 34 nm, and may be within the range where these are the upper limit value or the lower limit value of the above numerical range, or may be within the range of combinations thereof. The average particle diameter is the arithmetic average particle diameter determined by electron microscope observation of 1000 particles of carbon black before being blended in the resin composition.

[0043] (D) The carbon black content is 0.8 to 15 parts by mass (for example, 0.9 to 15 parts by mass, or 1 to 15 parts by mass) with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, and 0.8 to 12 parts by mass (for example, 0.9 to 12 parts by mass, or 1 to 12 parts by mass) is preferable. By including (D) carbon black in an amount of 0.8 to 15 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, a low gloss polybutylene terephthalate resin composition excellent in blackness and having little gloss unevenness can be obtained. From the viewpoint of easily obtaining a polybutylene terephthalate resin composition having more excellent blackness, less gloss unevenness, and more excellent low gloss property, the content of (D) carbon black is more preferably 0.8 to 11 parts by mass (0.9 to 11 parts by mass, 1 to 11 parts by mass) with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, further preferably 0.8 to 10 parts by mass, still more preferably 0.8 to 8 parts by mass, and may be 1 to 6 parts by mass. In one embodiment, the content of (D) carbon black may be 1.3 parts by mass, may be 2.6 parts by mass, may be 5.3 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin, and may be in a range using these as the upper limit value or the lower limit value of the above numerical range, or may be a combined range of these.

[0044] <(F) Phosphorus-based compound> The resin composition may optionally contain a (F) phosphorus-based compound. By containing the (F) phosphorus-based compound, the mold release property during injection molding and the heat resistance of the molded product can be improved.

[0045] Examples of the phosphorus-based compound include organic phosphite-based compounds, organic phosphonite-based compounds, alkali metal phosphates, alkaline earth metal phosphates, and the like. Examples of the organic phosphite compound include bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, and the like. Examples of the organic phosphonite compound include tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphonite and the like. Examples of the alkali metal phosphate include alkali metal salts such as potassium phosphate, sodium phosphate [sodium dihydrogen phosphate (sodium phosphate dihydrate), disodium phosphate (sodium hydrogen phosphate, monosodium hydrogen phosphate, disodium hydrogen phosphate), etc.]. Examples of the alkaline earth metal phosphate include alkaline earth metal salts such as calcium phosphate [calcium dihydrogen phosphate (calcium bis(dihydrogen phosphate) monohydrate, etc.), calcium hydrogen phosphate (calcium hydrogen phosphate dihydrate, etc.)], magnesium phosphate (magnesium hydrogen phosphate, magnesium dihydrogen phosphate, etc.). The alkali metal salt or alkaline earth metal salt may be either an anhydride or a hydrate. (F) The phosphorus-based compound can be used alone or in combination of two or more.

[0046] Among these phosphorus-based compounds, one or more selected from alkali metal phosphates, alkaline earth metal phosphates, and organic phosphites are preferred.

[0047] (F) The content of the phosphorus-based compound is preferably 0.01 to 2.0 parts by mass, more preferably 0.05 to 1.0 parts by mass, based on 100 parts by mass of the (A) polybutylene terephthalate resin.

[0048] (Other resin components) The resin composition may contain other thermoplastic resins other than the (A) polybutylene terephthalate resin and the (B) polycarbonate resin as long as the effects of the present disclosure are not impaired. Examples of the other thermoplastic resins include polyethylene terephthalate, acrylonitrile styrene resin, etc. The content of the other thermoplastic resin is preferably 0 to 20 parts by mass, preferably 0 to 10 parts by mass, and may be 0 to 5 parts by mass, based on 100 parts by mass of the (A) polybutylene terephthalate resin.

[0049] The resin composition may generally contain an elastomer (e.g., ABS, core-shell elastomer, etc.) used to improve impact resistance. However, since a large refractive index difference from polybutylene terephthalate or polycarbonate easily causes whitening, the refractive index of the elastomer is preferably about 1.55 to 1.60 in order to further enhance the 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. However, since the refractive index of the acrylic resin used in the shell or the like is low and it easily whitens, its content is preferably less than 2% by mass, more preferably less than 1% by mass, based on the total amount (100% by mass) of the resin composition.

[0050] (Other fillers) The resin composition may optionally contain other fillers (excluding (C) glass flakes). As the filler, depending on the purpose, fibrous fillers, powdery and granular fillers (excluding carbon black), and plate-like fillers (excluding glass flakes) can be used. The content of the other fillers is preferably 0 to 60 parts by mass, more preferably 0 to 50 parts by mass, still more preferably 0 to 30 parts by mass, and may be 0 to 20 parts by mass, based on 100 parts by mass of the (A) polybutylene terephthalate resin.

[0051] Glass fibers are likely to be oriented and less likely to cause diffuse reflection in molded products by injection molding, so uneven gloss is likely to occur. In one embodiment, from the viewpoint of easily realizing a low-gloss polybutylene terephthalate resin composition, the content of glass fibers in the resin composition is preferably less than 20 parts by mass, more preferably less than 10 parts by mass, still more preferably less than 5 parts by mass, and particularly preferably less than 1 part by mass, based on 100 parts by mass of the (A) polybutylene terephthalate resin.

[0052] (Additives) In the resin composition, within a range not detrimental to the effects of the present disclosure, in addition to the above components, known additives generally added to thermoplastic resins and thermosetting resins, namely, burr inhibitors, mold 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. may be blended.

[0053] The method for adjusting the resin composition is not limited. For example, a method of pelletizing by melt-kneading and extruding each component using a melt-kneading device such as a single-screw or twin-screw extruder, or a method of preparing pellets (master batches) with different compositions and mixing a predetermined amount of those pellets, etc. may be mentioned. The pellets may be prepared, for example, by melt-mixing the components excluding the brittle components (such as glass flakes, etc.) and then mixing the brittle components.

[0054] The resin composition is excellent in low gloss and has little gloss unevenness. In one embodiment, the resin composition preferably has a 60° glossiness in accordance with JIS-Z-8741 of the molded article of 27 or less, more preferably 23 or less. In one embodiment, for the molded articles injection-molded at an injection speed of 30 mm / s, 80 mm / s, or 120 mm / s, the 60° glossiness in accordance with JIS-Z-8741:1997 is preferably 27 or less, more preferably 23 or less. The glossiness can be measured at an angle of 60° using a gloss meter (e.g., Handy Gloss Meter PG-II manufactured by Nippon Denshoku Industries Co., Ltd.).

[0055] In one embodiment, the resin composition is excellent in jet blackness. In one embodiment, the resin composition preferably has an L* value in accordance with JIS-Z-8781-4:2013 of the molded article of 14 or less, more preferably 13 or less. Since it is excellent in jet blackness, it can absorb light and prevent reflection. In one embodiment, for the L* values measured by the above method at arbitrarily selected three locations on the molded article, all are preferably 14 or less, more preferably 13 or less.

[0056] (Use) Since the resin composition of the present disclosure is excellent in blackness, has little gloss unevenness, and has low gloss, it can be preferably used in the production of members for various optical devices and members for display devices. For example, it can be preferably used in the production of members used in drive recorders, back cameras, ADAS, head-up displays, liquid crystal meters, car navigators, etc.

[0057] [Molded article] The molded article contains the above-mentioned polybutylene terephthalate resin composition. Since it contains the above polybutylene terephthalate resin composition, it is excellent in blackness and low gloss, and has little gloss unevenness depending on the part of the molded article.

[0058] In one embodiment, the molded article preferably has a 60° glossiness conforming to JIS-Z-8741 of 27 or less, more preferably 23 or less. In one embodiment, the molded article preferably has a 60° glossiness measured by the above method at any three arbitrarily selected locations of 27 or less, more preferably 23 or less.

[0059] In one embodiment, the molded article preferably has an L* value conforming to 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 any three arbitrarily selected locations of 14 or less, more preferably 13 or less.

[0060] In order to enhance the lower glossiness, the surface of the molded article may be subjected to embossing, but since it is excellent in lower glossiness and has little gloss unevenness by containing the above resin composition, the surface may not be subjected to embossing. In order to enhance the lower glossiness, the surface of the molded article may be coated with a matting agent, but since it is excellent in lower glossiness and has little gloss unevenness by containing the above resin composition, the surface may not be coated with a matting agent. Examples of the matting agent include acrylic-based, urethane-based, and epoxy-based paints.

[0061] The method for molding the molded product is not limited, and it may be molded by a conventional method such as extrusion molding, injection molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc., but it is usually molded by injection molding. The mold temperature during injection molding is usually 40 to 120 °C, preferably 50 to 80 °C, and more preferably about 60 to 80 °C.

Examples

[0062] Examples are shown below to explain the present disclosure more specifically, but the interpretation of the present disclosure is not limited by these examples.

[0063] <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 flake (manufactured by Nippon Sheet Glass Co., Ltd., Fine Flake MEG160FY-M01), average thickness 0.7 μm, average particle diameter 160 μm (manufacturer catalog value) C-2: Glass flake (manufactured by Nippon Sheet Glass Co., Ltd. REFG-108), average thickness 5 μm, average particle diameter 600 μm (manufacturer 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 495 cm 3 / 100 g D-2: Carbon black (manufactured by Mitsubishi Chemical Corporation, Carbon black #750B), average particle size 22 nm, DBP absorption 116 cm 3 / 100 g D-3: Carbon black (manufactured by Mitsubishi Chemical Corporation, Carbon black #960B), average particle size 16 nm, DBP absorption 69 cm 3 / 100 g D-4: Carbon black (manufactured by Mitsubishi Chemical Corporation, Carbon black #2600), average particle size 13 nm, DBP absorption 77 cm 3 / 100 g E-1: Core-shell elastomer (manufactured by Kaneka Corporation, Kane Ace MP90) E-2: Core-shell elastomer (manufactured by Aika Industries Co., Ltd., Staffroid PO-0935) F: Monocalcium phosphate (manufactured by Taihei Chemical Industry Co., Ltd., transesterification inhibitor) G: Boron nitride (manufactured by Mizushima Alloy Iron Co., Ltd., nucleating agent) H: Fatty acid ester (manufactured by Riken Vitamin Co., Ltd., Rikemal B-150, lubricant)

[0064] [Examples 1 to 10, Comparative Examples 1 to 21] The raw materials were mixed at the ratios shown in Tables 1 and 2, and using a twin-screw extruder, melt kneaded and extruded at a cylinder temperature of 260°C and a screw rotation of 150 rpm to produce the polybutylene terephthalate resin compositions of Examples 1 to 10 and Comparative Examples 1 to 21. Using the obtained polybutylene terephthalate resin compositions, at a cylinder temperature of 260°C, a mold temperature of 80°C, and a holding pressure of 60 MPa, three flat molded articles (dimensions: 70 mm × 50 mm × thickness 3 mm) were molded with an injection speed of 30 mm / s, 80 mm / s, or 120 mm / s.

[0065] [Measurement and Evaluation] By the following method, the 60° glossiness and lightness L* of each of the obtained molded articles were measured. The results are shown in Tables 1 and 2.

[0066] <60° Glossiness> The glossiness (%) was measured in accordance with JIS-Z-8741:1997 using a handy gloss meter PG-II(60°) manufactured by Nippon Denshoku Industries Co., Ltd. Based on the following criteria, low glossiness and gloss unevenness were evaluated. (Low glossiness) 3: The glossiness of all three molded products with different injection speeds is 23% or less (excellent low glossiness and little gloss unevenness) 2: The glossiness of all three molded products with different injection speeds is 27% or less (good low glossiness) 1: The glossiness of one or more of the three molded products with different injection speeds exceeds 27% (poor low glossiness (high glossiness)) (Gloss unevenness) 3: The difference between the maximum and minimum glossiness of the three molded products with different injection speeds is 5 or less 2: The difference between the maximum and minimum glossiness of the three molded products with different injection speeds exceeds 5 and is 10 or less 1: The difference between the maximum and minimum glossiness of the three molded products with different injection speeds exceeds 10

[0067] (Brightness L*) The L* value was measured in accordance with JIS-Z-8781-4:2013 using an SM-P type color computer manufactured by Suga Test Instruments Co., Ltd. Based on the following criteria, blackness was evaluated. 3: The L* value of all three molded products with different injection speeds is 13 or less (excellent blackness) 2: The L* value of all three molded products with different injection speeds exceeds 13 and is 14 or less (good blackness) 1: The L* value of one or more of the three molded products with different injection speeds exceeds 14

[0068] (Median diameter of glass flakes) A molded product made of a polybutylene terephthalate resin composition (among the above molded products, the molded product molded at an injection speed of 80 mm / s) was treated in an electric furnace at 600 °C for 4 hours, and the remaining residue was used to calculate the median diameter of the glass flakes with a laser diffraction / scattering particle size distribution measuring device LA-960 manufactured by Horiba, Ltd.

[0069]

Table 1

Table 2

[0070] As shown in Table 1, the resin compositions of Examples 1 to 10 are excellent in blackness and can provide low-gloss molded articles with little gloss unevenness.

Industrial Applicability

[0071] Since the resin composition of the present disclosure is excellent in blackness, has little gloss unevenness, and is low in gloss, it can be preferably used for manufacturing members for various optical devices and members for display devices, and has industrial applicability.

Claims

Claim 1 comprising (A) a polybutylene terephthalate resin, (B) a polycarbonate resin, (C) glass flakes, and (D) carbon black, wherein (A) the polybutylene terephthalate resin comprises a modified polybutylene terephthalate resin containing (a1) 5 to 30 mol% of comonomer units, wherein the average thickness of (C) the glass flakes is 1 μm or less and the median diameter is 5 to 70 μm, per 100 parts by mass of (A) the polybutylene terephthalate resin, the content of (B) the polycarbonate resin is 60 to 100 parts by mass, the content of (C) the glass flakes is 60 to 100 parts by mass, the content of (D) the carbon black is 0.8 to 15 parts by mass, the modified polybutylene terephthalate resin is an isophthalic acid-modified polybutylene terephthalate copolymer, and the (B) polycarbonate resin is a bisphenol A-type polycarbonate, a polybutylene terephthalate resin composition. Claim 2 The polybutylene terephthalate resin composition according to claim 1, further comprising (F) a phosphorus compound. Claim 3 A molded article comprising the resin composition according to claim 1 or 2.

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