Laser-transmissive resin composition and molded article thereof

Abstract

To provide a laser transmissive resin composition that has high laser transmittance and shows good color development without color transfer, and a molded article using the same.SOLUTION: This laser transmissive resin composition (I) comprises, per 100 pts.mass of polyester-based resin (A), 0.005-5.0 pts.mass of organic pigment (B) containing at least benzimidazolone-based yellow pigment (b1). A molded article of this resin composition (I) with a thickness of 1 mm has a CIE L* value of 25 or less and a 940 nm laser transmittance of 40% or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a laser-transparent resin composition and a molded article thereof.

Background Art

[0002] Welding is a method applied to thermoplastic resins. After applying heat to the parts of the resin product to be joined to melt them, the parts are brought into close contact and cooled and solidified to be joined. Among these, laser welding involves overlapping a laser-transparent resin and a resin containing a laser absorber, and irradiating the laser to join the resins. In laser welding, diode lasers or YAG lasers with wavelengths slightly longer than visible light, around 800 to 1200 nm, are generally used. If laser transparency and absorbability can be ensured in this wavelength range, joining is possible, and it is also possible to join colored resin products by selecting dyes or laser absorbers.

[0003] The laser transparency varies depending on the resin, and is applied to resins with high transparency and high laser transparency such as polycarbonate resins, polymethyl (meth) acrylate resins (PMMA resins), polystyrene resins (PS resins), translucent resins such as polyacetal resins (POM resins) and polyamide resins (PA resins), and resins with high concealability and low laser transparency such as polyester resins. Resins with relatively high transparency also have high laser transparency, so they can develop sufficient color even with a small amount of colorant, and can maintain high laser transparency. On the other hand, polyester resins with low laser transparency are difficult to laser-weld, and methods such as combining amorphous resins (for example, Patent Document 1) or adding colorants with high transparency (for example, Patent Document 2) are adopted.

[0004] Regarding laser-transparent colorants, for example, Patent Document 3 describes that a mixture of perylene-based red, isoindolinone-based yellow, and phthalocyanine-based blue can be used to color a laser-transparent resin black. Conventionally, colorants used for laser welding have emphasized transparency, and dyes and pigments with relatively small particle diameters have been used. Such colorants are suitable for laser welding because of their excellent transparency. However, the dye itself has low heat resistance, and when used at high temperatures, the colorant sublimates or fades. In addition, there are problems such as color transfer when the members are in contact or contamination of the members.

[0005] Regarding the above problems, Patent Document 4 describes that a laser light-transmissive resin composition containing an anthraquinone-based and / or naphthalimide-based polymer dye is less likely to transfer color to other articles during laser welding. Further, Patent Document 5 describes that a thermoplastic coloring resin composition for laser welding containing a metal oxide not containing Mn is less likely to fade even in a high-temperature environment. Furthermore, Patent Document 6 describes that a polyester resin composition for laser welding having a colorant containing a phthalocyanine-based pigment is less likely to fade or undergo thermal degradation. However, none of these resin compositions sufficiently suppress color transfer during laser welding.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a laser-transparent resin composition having high laser transparency, good color development, and no color migration, and a molded article using the same.

Means for Solving the Problems

[0008] As a result of intensive studies by the present inventors, it has been found that by blending a certain amount of an organic pigment containing at least a benzimidazolone-based yellow pigment with a polyester-based resin, a laser-transparent resin composition capable of solving all of the above problems can be obtained, and the present invention has been completed. That is, the present invention has the following aspects. [1] A laser-transparent resin composition (I) containing 0.005 to 5.0 parts by mass of an organic pigment (B) containing at least a benzimidazolone-based yellow pigment (b1) with respect to 100 parts by mass of a polyester-based resin (A), wherein the CIE L * value of a molded article having a thickness of 1 mm of the resin composition (I) is 25 or less, and the laser transmittance at 940 nm is 40% or more. [2] The laser-transparent resin composition (I) according to [1], wherein the organic pigment (B) contains at least one pigment selected from the benzimidazolone-based yellow pigment (b1), a phthalocyanine-based blue pigment (b2), and a perylene-based red pigment (b3). [3] The yellow pigment (b1) contains at least one pigment selected from Pigment Yellow 180 and Pigment Yellow 181, the blue pigment (b2) contains at least one pigment selected from Pigment Blue 15:3 and Pigment Blue 16, and the red pigment (b3) contains Pigment Red 149. The laser-transparent resin composition (I) according to [2]. [4] The laser-transparent resin composition (I) according to any one of [1] to [3], wherein the polyester-based resin (A) contains a polybutylene terephthalate-based resin. [5] The laser-transparent resin composition (I) according to any one of [1] to [4], further containing an inorganic filler (C). [6] The laser-transmissive resin composition (I) according to any one of [1] to [5], further containing an amorphous resin (D). [7] A molded article obtained by using the laser-transmissive resin composition (I) according to any one of [1] to [6].

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a laser-transmissive resin composition having high laser transmissivity, good color development, and no color shift, and a molded article using the same.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range that does not inhibit the effects of the present invention. In this specification, the description of "~" means "more than or equal to and less than or equal to". For example, "0.005 to 5.0 parts by mass" means "0.005 parts by mass or more and 5.0 parts by mass or less".

[0011] [Laser-Transmissive Resin Composition (I)] The laser-transmissive resin composition (I) according to the present invention is a laser-transmissive resin composition (I) containing 0.005 to 5.0 parts by mass of an organic pigment (B) containing at least a benzimidazolone-based yellow pigment (b1) with respect to 100 parts by mass of a polyester-based resin (A). The CIE L of a molded article having a thickness of 1 mm of the resin composition (I) * value is 25 or less, and the 940 nm laser transmittance is 40% or more. The laser-transmissive resin composition (I) of this embodiment (hereinafter simply referred to as "resin composition (I)") has high laser transmissivity, good color development, and no color shift.

[0012] The CIE L of a molded article having a thickness of 1 mm of the resin composition (I) according to the present invention * value is 25 or less, preferably 23 or less, and more preferably 20 or less. The molded article having a thickness of 1 mm of the resin composition (I) according to the present invention has a CIE L *Since the value is 25 or less, it exhibits a dark color. Note that "CIE" is a quantitative color representation method defined by the Commission Internationale de l'Eclairage. Also, "L * value" is an index representing lightness. The CIE L * value in the molded article of the resin composition (I) according to the present invention specifically refers to the value measured by the following method. (Measurement method of CIE L * value) The resin composition (I) is injection molded under the conditions of a cylinder temperature of 260°C and a mold temperature of 80°C to prepare a test piece (molded article) of 80 mm × 80 mm × 1 mm thickness. The obtained test piece is measured using a color computer (manufactured by Nippon Denshoku Co., Ltd., product name: Spectrophotometric Color Difference Meter SE6000) under the conditions of a pore diameter of φ10 mm, a C light 2° field of view, and reflection, and the measured value is taken as the CIE L * value.

[0013] The resin composition (I) according to the present invention has a laser transmittance of 40% or more at a wavelength of 940 nm. The laser transmittance is preferably 42% or more, and more preferably 44% or more. If the laser transmittance is 40% or more, the molded article obtained from the resin composition (I) according to the present invention can be easily joined to other members by laser welding. The laser transmittance in the molded article of the resin composition (I) according to the present invention specifically refers to the value measured by the following method. (Measurement method of laser transmittance) The resin composition (I) is injection molded under the conditions of a cylinder temperature of 260°C and a mold temperature of 80°C to prepare a test piece (molded article) of 80 mm × 80 mm × 1 mm thickness. The transmittance of a 940 nm laser is measured for the obtained test piece using a spectrophotometer (manufactured by JASCO Corporation, product name: UV-Visible Near-Infrared Spectrophotometer V-770, integrating sphere ISN-923).

[0014] <Polyester resin (A)> The resin composition (I) according to the present invention contains a polyester resin (A). From the viewpoint of moldability of the resin composition (I), the proportion of the polyester resin (A) in the resin composition (I) is preferably 30 to 90 mass %, more preferably 35 to 80 mass %, and even more preferably 45 to 70 mass %, relative to the total mass of the resin composition (I).

[0015] As the polyester resin (A), a conventionally known polyester resin may be used alone or in combination of two or more. A polyester resin composed of a dicarboxylic acid or a derivative thereof and a diol is preferred. Examples of dicarboxylic acids or derivatives thereof include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, aliphatic dicarboxylic acids, or ester-forming derivatives thereof. Among these, it is preferable to include aromatic dicarboxylic acids or ester-forming derivatives thereof. Examples of polyester-based resins (A) containing aromatic dicarboxylic acids or ester-forming derivatives thereof include polyethylene terephthalate-based resins (PET resins), polybutylene terephthalate-based resins (PBT resins), polytetramethylene terephthalate-based resins (PTT), etc. Among these, it is preferable to include PBT resins, PET resins, and PTT resins from the viewpoints of mechanical properties and laser transmittance, and it is more preferable to include PBT resins from the viewpoint of moldability. In one embodiment, the polyester-based resin (A) may be a PBT resin.

[0016] (PBT resin) The PBT resin is obtained by polycondensation of an aromatic dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (such as an alkyl ester or acid halide having 1 to 6 carbon atoms) and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (such as an acetylated product). In this embodiment, the PBT resin is not limited to a homopolybutylene terephthalate resin, and may be a copolymer containing 60 mol % or more of butylene terephthalate units.

[0017] The amount of carboxyl group terminals in the PBT resin is preferably 50 meq / kg or less, more preferably 30 meq / kg or less, and even more preferably 25 meq / kg or less. The amount of carboxyl group terminals is a value representing the amount of unreacted carboxylic acid groups in the polymer chain. If the amount of carboxyl group terminals is 50 meq / kg or less, the hydrolysis resistance tends to be good. The amount of carboxyl group terminals can be determined by heating and dissolving in benzyl alcohol at 215°C for 10 minutes and then titrating with a 0.01N aqueous sodium hydroxide solution.

[0018] The intrinsic viscosity of the PBT resin can be appropriately adjusted within a range that does not inhibit the object of the present invention. From the viewpoint of fluidity, it is preferably 0.60 dL / g or more and 1.20 dL / g or less, and more preferably 0.65 dL / g or more and 0.90 dL / g or less. Also, PBT resins having different intrinsic viscosities may be blended to adjust the intrinsic viscosity. For example, a PBT resin having an intrinsic viscosity of 0.80 dL / g can be prepared by blending a PBT resin having an intrinsic viscosity of 0.90 dL / g and a PBT resin having an intrinsic viscosity of 0.70 dL / g. The intrinsic viscosity of the PBT resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0019] In the preparation of the PBT resin, when using an aromatic dicarboxylic acid other than terephthalic acid or its ester-forming derivative as a comonomer component, for example, aromatic dicarboxylic acids having 8 to 14 carbon atoms such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether; alkanedicarboxylic acids having 4 to 16 carbon atoms such as succinic acid, adipic acid, azelaic acid, sebacic acid; cycloalkanedicarboxylic acids having 5 to 10 carbon atoms such as cyclohexanedicarboxylic acid; ester-forming derivatives of these dicarboxylic acid components (alkyl ester derivatives having 1 to 6 carbon atoms, acid halides, etc.) can be used. These dicarboxylic acid components may be used alone or in combination of two or more. Among the above dicarboxylic acid components, aromatic dicarboxylic acids having 8 to 14 carbon atoms such as isophthalic acid; alkane dicarboxylic acids having 4 to 16 carbon atoms such as adipic acid, azelaic acid, and sebacic acid are preferred.

[0020] In the preparation of PBT resin, when using a glycol component other than 1,4-butanediol as a comonomer component, for example, alkylene glycols having 2 to 10 carbon atoms such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol; alicyclic diols such as cyclohexanedimethanol, hydrogenated bisphenol A; aromatic diols such as bisphenol A, 4,4'-dihydroxybiphenyl; alkylene oxide adducts of bisphenol A having 2 to 4 carbon atoms such as 2-mole ethylene oxide adduct of bisphenol A, 3-mole propylene oxide adduct of bisphenol A; or ester-forming derivatives (such as acetylated products) of these glycols can be used. These glycol components may be used alone or in combination of two or more. Among these glycol components, alkylene glycols having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, or alicyclic diols such as cyclohexanedimethanol are more preferred.

[0021] The PBT resin may contain other comonomer components in addition to the aforementioned dicarboxylic acid component and glycol component. Examples of other comonomer components 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; lactones having 3 to 12 carbon atoms such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); and ester-forming derivatives of these comonomer components (alkyl ester derivatives having 1 to 6 carbon atoms, acid halides, acetylated products, etc.). These comonomer components may be used alone or in combination of two or more.

[0022] The proportion of the PBT resin contained in the polyester resin (A) is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total mass of the polyester resin (A). Also, the proportion of the PBT resin in the polyester resin (A) may be 100% by mass. Further, the proportion of the PBT resin in the resin composition (I) is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 50 to 70% by mass, based on the total mass of the resin composition (I).

[0023] (PET resin) The PET resin is obtained by polycondensation reaction of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative and a glycol component containing at least an alkylene glycol having 2 carbon atoms (ethylene glycol) or its ester-forming derivative. The PET resin may be a homopolymer PET resin or a copolymer (copolymer PET) resin containing 60 mol% or more (particularly about 75 mol% to 95 mol%) of ethylene terephthalate units.

[0024] In the copolyester PET resin, examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include aromatic dicarboxylic acid components (aryl dicarboxylic acids having 6 to 12 carbon atoms such as isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, etc.), aliphatic dicarboxylic acid components (alicyclic dicarboxylic acids having 5 to 10 carbon atoms such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc.), aromatic hydroxycarboxylic acids (hydroxybenzoic acid, hydroxynaphthoic acid, etc.), and their ester-forming derivatives. Preferred dicarboxylic acid components (comonomer components) include aromatic dicarboxylic acid components (especially aryl dicarboxylic acids having 6 to 10 carbon atoms such as isophthalic acid), and aliphatic dicarboxylic acid components (especially alkyl dicarboxylic acids having 6 to 12 carbon atoms such as adipic acid, azelaic acid, sebacic acid).

[0025] Examples of glycol components (comonomer components) other than ethylene glycol include aliphatic diol components [e.g., alkylene glycols (alkylene glycols having 3 to 10 carbon atoms such as propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol, etc.); polyoxy C2-C4 alkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, etc.], alicyclic diol components such as cyclohexanedimethanol, hydrogenated bisphenol A, etc., aromatic diol components [aromatic alcohols such as bisphenol A, 4,4'-dihydroxybiphenyl, etc.; alkylene oxide adducts of bisphenol A having 2 to 4 carbon atoms (e.g., ethylene oxide 2-mol adduct of bisphenol A, propylene oxide 3-mol adduct of bisphenol A, etc.)], or their ester-forming derivatives. These glycol components can also be used alone or in combination of two or more.

[0026] Preferred glycol components (comonomer components) include aliphatic diol components (especially alkylene glycols having 3 to 6 carbon atoms, polyoxy C2-C3 alkylene glycols such as diethylene glycol; alicyclic diols such as cyclohexanedimethanol). The homo-PET resin and the copolymerized PET resin can be used alone or in combination of two or more thereof. Furthermore, the comonomer unit of the copolymerized PET resin is at least one selected from aromatic dicarboxylic acid residues (especially at least alkylene glycol residues having 3 to 10 carbon atoms, polyoxy C2-C3 alkylene glycol residues). The copolymerized PET resin includes isophthalic acid copolymerized PET resin (isophthalic acid-modified PET resin) and the like.

[0027] (PTT resin) The PTT resin is obtained by a polycondensation reaction of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative and at least 1,3-propanediol having 3 carbon atoms. The PTT resin is not limited to the homo-PTT resin, and may be a copolymer (copolymerized PTT) resin containing 60 mol% or more of tetramethylene terephthalate units.

[0028] In the case of the copolymerized PTT, monomers to be copolymerized include dicarboxylic acids, dicarboxylic acid esters, and the like. Specific examples include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid, 2-potassium sulfoisophthalic acid, 2-lithium sulfoisophthalic acid, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid, 2-sodium sulfo-4-hydroxybenzoic acid, 5-sulfoisophthalic acid tetrabutylphosphonium, and lower alcohol esters thereof such as methanol, and oxyacetic acid. These can be used alone or in combination of two or more.

[0029] <Organic Pigment (B)> The resin composition (I) according to the present invention contains 0.005 to 5.0 parts by mass of an organic pigment (B) containing at least a benzimidazolone-based yellow pigment (b1) with respect to 100 parts by mass of the polyester resin (A). By containing such an organic pigment (B), a resin composition (I) and its molded article having good color development and no color shift can be obtained. Note that "good color development" means that coloring can be achieved with a small amount of pigment and there is no color development unevenness. The proportion of the organic pigment (B) in the resin composition (I) is preferably 0.1 to 0.8 parts by mass, more preferably 0.2 to 0.7 parts by mass, and particularly preferably 0.3 to 0.6 parts by mass with respect to 100 parts by mass of the polyester resin (A).

[0030] (benzimidazolone-based yellow pigment (b1)) The organic pigment (B) contains at least a benzimidazolone-based yellow pigment (b1) (hereinafter referred to as "yellow pigment (b1)"). The yellow pigment (b1) is an organic yellow pigment containing a benzimidazolone structure in its skeleton. Examples of the yellow pigment (b1) include Pigment Yellow 120, Pigment Yellow 151, Pigment Yellow 154, Pigment Yellow 175, Pigment Yellow 180, Pigment Yellow 181, Pigment Yellow 194, etc., which are indicated by the Color Index (CI) name and number jointly established by the Society of Dyers and Colourists, UK and the American Association of Textile Chemists and Colorists. These may be used alone or in combination of two or more. Among these, from the viewpoint of easily obtaining a resin composition (I) with less color shift, it is preferable to contain at least one yellow pigment selected from Pigment Yellow 180 and Pigment Yellow 181.

[0031] Pigment Yellow 181, which is one of the preferred examples of the yellow pigment (b1), is a compound represented by 4'-carbamoyl-4-[1-(2,3-dihydro-2-oxo-1H-benzimidazol-5-ylcarbamoyl)acetonylazo]benz anilide.

[0032] The proportion of the yellow pigment (b1) in the organic pigment (B) is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass based on the total mass of the organic pigment (B). Further, the proportion of the yellow pigment (b1) in the resin composition (I) is preferably 0.01 to 0.4 parts by mass, more preferably 0.05 to 0.35 parts by mass, and even more preferably 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the polyester resin (A).

[0033] The organic pigment (B) preferably contains the yellow pigment (b1) and at least one pigment selected from phthalocyanine-based blue pigments (b2) and perylene-based red pigments (b3). Such an organic pigment (B) makes it easier to adjust the CIE L * value of a molded article having a thickness of 1 mm of the resin composition (I) to 25 or less. Further, the organic pigment (B) more preferably contains the yellow pigment (b1), the phthalocyanine-based blue pigment (b2), and the perylene-based red pigment (b3).

[0034] (Phthalocyanine-based blue pigment (b2)) The organic pigment (B) may contain a phthalocyanine-based blue pigment (b2) (hereinafter referred to as "blue pigment (b2)"). The blue pigment (b2) is a pigment having a phthalocyanine skeleton in its structure. Specifically, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Blue 15:6, Pigment Blue 16, Pigment Blue 17:1, Pigment Blue 75, Pigment Blue 79, etc., represented by the aforementioned CI names and numbers, can be mentioned. These may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining a resin composition (I) that is less likely to undergo color shift and has good color development, it is preferable to contain at least one blue pigment selected from Pigment Blue 15:3 and Pigment Blue 16.

[0035] When the organic pigment (B) contains a blue pigment (b2), its content is preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and still more preferably 25 to 40% by mass with respect to the total mass of the organic pigment (B) from the viewpoint of color mixing. By including the blue pigment (b2) as the complementary color to the benzimidazolone yellow pigment (b1), it is possible to approach achromatic color and make it easier to control the b * value. Further, the content of the blue pigment (b2) in the resin composition (I) is preferably 0.01 to 0.4 parts by mass, more preferably 0.05 to 0.35 parts by mass, and still more preferably 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the polyester resin (A).

[0036] (Perylene-based red pigment (b3)) The organic pigment (B) may contain a perylene-based red pigment (b3) (hereinafter referred to as "red pigment (b3)"). The red pigment (b3) is a pigment having a structure in which two oxygen atoms constituting the six-membered ring of perylene tetracarboxylic dianhydride are removed. Specifically, Pigment Red 149, Pigment Red 179, etc. represented by the aforementioned CI names and numbers can be mentioned. These may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining a resin composition (I) that is less likely to undergo color shift and has good color development, it is preferable to contain Pigment Red 149.

[0037] When the organic pigment (B) contains the red pigment (b3), its content is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and still more preferably 30 to 40% by mass with respect to the total mass of the organic pigment (B). Further, the content of the red pigment (b3) in the resin composition (I) is preferably 0.01 to 0.4 parts by mass, more preferably 0.05 to 0.35 parts by mass, and still more preferably 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the polyester resin (A).

[0038] (Other pigments) The organic pigment (B) can include pigments other than the yellow pigment (b1), blue pigment (b2), and red pigment (b3). The other pigments can be appropriately selected and used from organic pigments used as colorants for the laser-transmissive resin composition from the perspective of adjusting the CIE L * value to a more preferable range of the present invention. Note that a resin composition (I) that does not undergo color migration is easily obtained, and from the perspective of color reproducibility, it is preferable that the organic pigment (B) does not contain other pigments.

[0039] <Inorganic filler (C)> The resin composition (I) preferably contains an inorganic filler (C). By including the inorganic filler (C), the mechanical strength and heat resistance become good. Examples of the inorganic filler (C) include fibrous inorganic fillers such as glass fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, and boron fiber; and plate-like inorganic fillers such as mica and glass flake. These may be used alone or in combination of two or more. Among these, from the perspective of mechanical strength and moldability, the inorganic filler (C) preferably contains a fibrous inorganic filler, and more preferably contains glass fiber. As the glass fiber, those having an average fiber length in the range of 150 to 800 μm are preferable, and 200 to 600 μm are more preferable. If the glass fiber length is short, the effect of improving the strength is low, and if the glass fiber length is too long, the fluidity decreases and the dispersibility of the glass fiber easily deteriorates. Also, the glass fiber diameter is preferably 5 to 20 mm, and more preferably 10 to 18 mm. If the glass fiber diameter is small, the scattering of the resin and the glass fiber increases due to laser irradiation and the transmittance easily decreases, and if the glass fiber diameter is too large, it easily clogs at the thin parts of the nozzle and the cavity during molding. Note that the average fiber length is a value obtained by calculating the weight average fiber length after ashing the molded product in an electric furnace at 600°C, dispersing the obtained glass fiber in a solvent such as water, and excluding glass fibers of 50 μm or less using an image measuring device or the like.

[0040] When the resin composition (I) contains the inorganic filler (C), its content is preferably 40 to 80 parts by mass, more preferably 50 to 70 parts by mass, per 100 parts by mass of the polyester resin (A). If the content of the inorganic filler (C) is within the above range, the balance between fluidity and mechanical properties is more likely to be good.

[0041] <Amorphous resin (D)> The resin composition (I) preferably further contains an amorphous resin (D). By including the amorphous resin (D), the shrinkage rate decreases, and welding defects due to warping of the molded product are likely to be improved. The amorphous resin (D) is preferably a thermoplastic amorphous resin. Examples thereof include polyvinyl chloride-based resins (PVC resins), PS resins, PMMA resins, acrylonitrile-butadiene-styrene resins (ABS resins), acrylonitrile-styrene resins (AS resins), PC resins, modified polyphenylene ether-based resins (m-PPE resins), polyetherimide-based resins (PEI resins), polyamideimide-based resins (PAI resins), and the like. Among these, from the viewpoint of easily adjusting the 940 nm laser transmittance of a molded product with a thickness of 1 mm to 40% or more and easily improving the permeability, a PC resin, an AS resin, or a PS resin is preferable, and it is more preferable to contain a PC resin.

[0042] When the resin composition (I) contains the amorphous resin (D), its content is preferably 5 to 100 parts by mass, more preferably 15 to 35 parts by mass, per 100 parts by mass of the polyester resin (A).

[0043] <Other components> The resin composition (I) may contain components other than the aforementioned polyester resin (A), organic pigment (B), inorganic filler (C), and amorphous resin (D) (other components) in order to impart desired properties according to the purpose, as long as the effects of the present invention are not inhibited. As the other components, components conventionally blended in laser-transparent resins can be appropriately selected and used. For example, stabilizers such as antioxidants and ultraviolet absorbers, hydrolysis resistance improvers (e.g., epoxy resins, etc.), antistatic agents, flame retardants, flame retardant aids, dripping inhibitors, mold release agents, lubricants, lubricants, crystallization accelerators, crystal nucleating agents (excluding the inorganic filler (C)), plasticizers, thermoplastic elastomers, etc. can be blended. The total amount of these other components is preferably less than 30 parts by mass, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less with respect to 100 parts by mass of the polyester resin (A).

[0044] [Method for producing the laser-transparent resin composition (I)] The resin composition (I) according to the present invention can be prepared by adopting a conventionally known method as long as the effects of the present invention are not inhibited. For example, (1) a method of mixing the polyester resin (A), the organic pigment (B), the inorganic filler (C), the amorphous resin (D), and, if necessary, the aforementioned other components, and kneading and extruding them with a single-screw or twin-screw extruder to obtain pellets of the resin composition (I); (2) a method of once preparing pellets (master batches) with different compositions, and mixing (diluting) the pellets in a predetermined amount to obtain the composition of the resin composition (I); (3) a method of directly charging each component into a molding machine to obtain the resin composition (I), etc. can be adopted. The pellets may be prepared, for example, by melt-mixing the components excluding the brittle components (inorganic filler (C), glass-based reinforcing materials, etc.) and then mixing the brittle components.

[0045] [Molded article] The molded article according to the present invention is obtained by molding the resin composition (I) according to the present invention. The molding method is not particularly limited, and known molding methods can be adopted. For example, after obtaining the resin composition (I) by the methods of (1) to (3) described above, it can be molded into the molded article according to the present invention. Further, the molding method of other molded articles made of thermoplastic resin is also not particularly limited, and known molding methods can be adopted.

[0046] The molded article may be obtained by melt-kneading the resin composition (I) and molding it by a conventional method such as extrusion molding, injection molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc., but is usually molded by injection molding. The mold temperature during injection molding is usually 40 to 90°C, preferably 50 to 80°C, and more preferably about 60 to 80°C.

[0047] The shape of the molded article is not particularly limited, but since the molded article is used by being joined to a mating material (another molded article made of thermoplastic resin) by laser welding, it usually has a shape having at least a contact surface (such as a flat surface) (for example, a plate shape). Further, since the molded article according to the present invention has high transparency to laser light, the thickness of the molded article at the site where the laser light passes through (the thickness in the direction in which the laser light passes through) can be selected from a wide range, for example, 0.1 to 3 mm, preferably 0.1 to 2 mm, and more preferably about 0.5 to 1.5 mm.

[0048] The laser light source is not particularly limited, and for example, a dye laser, a gas laser (excimer laser, argon laser, krypton laser, helium-neon laser, etc.), a solid laser (YAG laser, etc.), a semiconductor laser, etc. can be used. As the laser light, a semiconductor laser is usually used.

[0049] Since the molded article according to the present invention is excellent in laser weldability, it is usually preferable to weld it to a resin molded article of a mating material by laser welding. If necessary, it can also be welded to other resin molded articles by other thermal welding methods, for example, vibration welding method, ultrasonic welding method, hot plate welding method, etc.

[0050] <Composite molded body> The molded product according to the present invention can be a composite molded body. The composite molded body according to the present invention is composed of a molded product (first molded product) made of a resin composition (I) and a resin molded product on the other side (second molded product, another molded product made of a thermoplastic resin), which are joined and integrated by laser welding. For example, by bringing the first molded product and the second molded product into contact (especially bringing at least the joint part into surface contact) and irradiating laser light, the interface between the first molded product and the second molded product is partially melted to make the joint surface adhere, and by cooling, the two molded products can be joined and integrated into one molded body (composite molded body). The composite molded body including the molded product according to the present invention has a high laser transmissivity, good color development, and does not undergo color migration, and is provided with a first molded product. Therefore, even when the first molded product and the second molded product are joined by laser welding, the color of the first molded product does not migrate to the second molded product and is also difficult to fade. In addition, since the molded product according to the present invention can maintain a high joint strength, a composite molded body in which the first molded product and the second molded product are firmly joined can be obtained in the composite molded body after laser welding. Also, the strength is not easily reduced before and after welding.

[0051] In the preparation of the composite molded body, the irradiation of the laser light is usually performed from the first molded product toward the second molded product. The laser light transmitted through the first molded product heats and melts the interface of the second molded product containing an absorber or a colorant, whereby the first molded product and the second molded product are welded. If necessary, a condensing lens or the like may be used to condense the laser light on the interface between the first molded product and the second molded product for welding.

[0052] (Second molded product) As the thermoplastic resin constituting the second molded article, a polyester resin is preferable. By using a polyester resin, high welding strength can be obtained. Examples of the polyester resin include the same ones as the aforementioned polyester resin (A). Further, as the thermoplastic resin constituting the second molded article, various thermoplastic resins other than the polyester resin, for example, olefin resins, vinyl resins, styrene resins, acrylic resins, polyamide resins, polycarbonate resins, etc. may be included. In particular, a polycarbonate resin, a styrene resin, an acrylic resin, or a resin composition containing at least one of them may constitute the second molded article.

[0053] The second molded article may contain an absorber or a colorant for laser light. As the colorant, it can be selected according to the wavelength of the laser light, and conventionally known inorganic pigments and organic pigments can be adopted. Examples of the inorganic pigment include black pigments such as carbon black (for example, acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, etc.); red pigments such as iron oxide red; orange pigments such as molybdate orange; white pigments such as titanium oxide, etc. Examples of the organic pigment include an organic pigment capable of developing yellow, orange, red, blue, green, etc. and having laser transparency. There is no particular limitation on their structures, and examples thereof include organic pigments such as azomethine-based, anthraquinone-based, quinacridone-based, dioxazine-based, diketopyrrolopyrrole-based, anthrapyridone-based, isoindolinone-based, indanthrone-based, perinone-based, perylene-based, indigo-based, thioindigo-based, quinophthalone-based, quinoline-based, and various dyes and pigments of triphenylmethane-based. These absorbents or colorants may be used alone or in combination of two or more. Among these, a black pigment, particularly carbon black, can be preferably used. The average particle diameter of carbon black can be 10 to 1000 nm, and preferably about 10 to 100 nm. The ratio of the absorbent or colorant is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, and even more preferably 0.3 to 3% by mass with respect to the total mass of the resin composition constituting the second molded article. When the thermoplastic resin constituting the second molded article does not contain an absorbent or colorant for laser light, it is possible to perform laser welding by applying an infrared absorbent or the like to the interface between the first molded article and the second molded article.

[0054] [Use] As described above, the resin composition (I) and the molded article thereof according to the present invention have high laser transparency, good color development, and no color transfer to other members. Therefore, they can be suitably used as a resin composition and a molded article for laser welding. Of course, the resin composition (I) and the molded article thereof according to the present invention are not limited to laser welding in terms of their uses.

[0055] A preferred embodiment of the present invention also includes a composite molded body obtained by welding and joining a molded article made of the resin composition (I) according to the present invention and a molded article (second molded article) made of the above thermoplastic resin. Another aspect of the present invention is the use of the organic pigment (B), preferably the yellow pigment (b1), as a color migration inhibitor for the resin composition for laser welding or a method of using the same. Further, the resin component contained in the resin composition for laser welding is preferably a polyester resin (A), more preferably a PBT resin. Further, as the resin component, only the PBT resin may be contained.

Examples

[0056] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by the following description.

[0057] <Materials> The materials used in the examples and comparative examples are as follows. · Polyester resin (A) (A-1): Isophthalic acid 12.5 mol modified polybutylene terephthalate resin (manufactured by Polyplastics Co., Ltd.) · Organic pigment (B) Yellow pigment (b1) (b1-1): Pigment Yellow 181 Blue pigment (b2) (b2-1): Pigment Blue 15:3 Red pigment (b3) (b3-1): Pigment Red 149 · Other organic pigment (B’) (B’-1): Phthalocyanine-based green pigment (Pigment Green 36) (B’-2): Phthalocyanine-based green pigment (Pigment Green 7) (B’-3): Monoazo-based yellow pigment (Pigment Yellow 183) (B’-4): Anthraquinone-based yellow pigment (Pigment Yellow 147) (B’-5): Isoindolinone-based yellow pigment (Pigment Yellow 110) (B’-6): Perylene-based purple pigment (Pigment Violet 29) (B’-7): Perylene-based black pigment (Lumogen black K0087) · Inorganic filler (C) (C-1): Glass fiber (manufactured by Nippon Electric Glass Co., Ltd., product name: ECS03 T-127 (average fiber diameter 13 μm, average fiber length 3 mm)) · Amorphous resin (D) (D-1): Polycarbonate resin (manufactured by Teijin Ltd., product name: Panlite (registered trademark) L-1225L) · Other components Thermoplastic elastomer: Polyester-based elastomer (manufactured by Toyobo Co., Ltd., product name: Pelprene (registered trademark) P-90BD) Hydrolysis resistance improver: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: 1004K) Antioxidant: Hindered phenol-based antioxidant (manufactured by BASF Japan Ltd., product name: IRGANOX (registered trademark) 1010) Lubricant: Diglycerin fatty acid ester (manufactured by Riken Vitamin Co., Ltd., product name: Rikemal (registered trademark) B74) Stabilizer: Calcium monophosphate (manufactured by Ohira Chemical Industry Co., Ltd.) Nucleating agent: Boron nitride (manufactured by Mizushima Alloy Iron Co., Ltd.) Plasticizer: Pyromellitic acid mixed linear alkyl ester (manufactured by ADEKA Corporation, product name: Adekaizer (registered trademark) UL-100)

[0058] [Examples 1 to 2] Based on 100 parts by mass of the polyester resin (A), the organic pigment (B) and other components were mixed at the ratios shown in Table 1, and then using a 30 mmφ twin-screw extruder (manufactured by Japan Steel Works, Ltd., product name: TEX-30), melt-kneaded and extruded at a cylinder temperature of 260°C, a discharge rate of 15 kg / hr, and a screw rotation speed of 130 rpm to obtain pellets composed of the resin composition (I). Next, these pellets were injection-molded at a cylinder temperature of 260°C and a mold temperature of 80°C to produce test pieces (molded products) of 80 mm × 80 mm × thickness 1 mm. The laser transmittance, CIE L * value, a * value, b *The value and the color transfer to the second molded product were evaluated by the method shown below. The results are shown in Table 1.

[0059] <CIE L * value, a * value, and b * Measurement method of value> The obtained test piece was measured under the conditions of a pore diameter of φ10 mm, a C light 2-degree field of view, and reflection using a color computer (manufactured by Nippon Denshoku Industries Co., Ltd., product name: Spectrophotometric Color Difference Meter SE6000).

[0060] <Measurement method of laser transmittance> The obtained test piece was used to measure the transmittance of a 940 nm laser using a spectrophotometer (manufactured by JASCO Corporation, product name: Ultraviolet-Visible-Near-Infrared Spectrophotometer V-770, integrating sphere ISN-923).

[0061] <Evaluation of color transfer> Natural color pellets of PBT resin (Polyplastics Co., Ltd., product name: Duranex (registered trademark) 3300 EF2001) were injection molded at a cylinder temperature of 260 °C and a mold temperature of 80 °C to obtain a second molded product of 20 mm × 20 mm × thickness 1 mm. The obtained second molded product and the obtained test piece were overlapped and heated at 130 °C for 30 hours, and then the presence or absence of color transfer to the second molded product was visually confirmed.

[0062] [Comparative Examples 1 to 4] Except that the composition of the resin composition was as shown in Table 1, a test piece (molded product) of 80 mm × 80 mm × thickness 1 mm was produced in the same manner as in Example 1. The laser transmittance, L * value, a * value, b * value, and the color transfer to the second molded product were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0063]

Table 1

[0064] As shown in Table 1, the resin compositions of Examples 1 to 2 that satisfy the configuration of the present invention had a high laser transmittance of the obtained molded products, good color development, and no color transfer when formed into a composite molded body. On the other hand, molded products obtained from the resin compositions of Comparative Examples 1 to 4 containing organic pigments other than the organic pigment (B) of the present invention showed color transfer to the second molded product when formed into a composite molded body. Further, Comparative Examples 1 to 3 also had low laser transmittance. From the above results, it was confirmed that the resin composition (I) according to the present invention and its molded product had high laser permeability, good color development, and no color transfer.

Claims

A laser-transmissive resin composition (I) comprising 0.005 to 5.0 parts by mass of an organic pigment (B) containing only a benzimidazolone-based yellow pigment (b1) and at least one pigment selected from a phthalocyanine-based blue pigment (b2) and a perylene-based red pigment (b3) per 100 parts by mass of a polyester resin (A) containing a polybutylene terephthalate-based resin, The laser-transmissive resin composition (I), wherein a molded article having a thickness of 1 mm of the resin composition (I) has a CIE L* value of 25 or less and a 940 nm laser transmittance of 40% or more.

2. The yellow pigment (b1) contains at least one pigment selected from Pigment Yellow 180 and Pigment Yellow 181, The blue pigment (b2) contains at least one pigment selected from Pigment Blue 15:3 and Pigment Blue 16, The laser-transmissive resin composition (I) according to claim 1, wherein the red pigment (b3) contains Pigment Red 149.

3. The laser-transmissive resin composition (I) according to claim 1 or 2, further comprising an inorganic filler (C).

4. The laser-transmissive resin composition (I) according to any one of claims 1 to 3, further comprising an amorphous resin (D).

5. A molded article obtained by using the laser-transmissive resin composition (I) according to any one of claims 1 to 4.

Images