Transparent resin composition for laser welding, kit, molded article, and method for producing molded article

Abstract

Provided are a permeable resin composition for laser welding having exceptional properties such as mechanical strength and low warpage as well as high light transmittance, a kit, a molded article, and a method for producing a molded article. A permeable resin composition for laser welding that includes 10-120 parts by mass of glass flakes having a thickness of 0.1-2 μm per 100 parts by mass of a crystalline thermoplastic resin, and a light-transmitting dye.

Description

Technical Field

[0001] The present invention relates to a permeable resin composition for laser welding, a kit, a molded article, and a method for manufacturing the molded article.

Background Art

[0002] Thermoplastic resins are easy to process and are widely used in vehicle parts, electrical and electronic equipment parts, and other precision equipment parts by taking advantage of their excellent properties. Recently, parts with complex shapes have also come to be manufactured using thermoplastic resins, particularly crystalline thermoplastic resins. For the adhesion of parts having a hollow portion such as an intake manifold, various welding techniques are used, specifically, adhesive welding, vibration welding, ultrasonic welding, hot plate welding, injection welding, laser welding techniques, and the like.

[0003] However, welding with an adhesive has problems such as environmental load problems such as contamination of the surroundings in addition to the time loss until curing. Ultrasonic welding, hot plate welding, etc. have been pointed out to have problems such as damage to the product due to vibration and heat, and the need for post-treatment due to the generation of abrasion powder and burrs. In addition, injection welding often requires special molds and molding machines, and further has problems such as not being able to be used if the fluidity of the material is not good.

[0004] On the other hand, laser welding is a method of bringing into contact and welding a resin member having permeability (also referred to as non-absorbability or weak absorbability) with respect to laser light (hereinafter sometimes referred to as a "permeable resin member") and a resin member having absorbability with respect to laser light (hereinafter sometimes referred to as an "absorbing resin member") to join the two resin members. Specifically, it is a method of irradiating laser light from the side of the permeable resin member to the joining surface and melting and joining the absorbing resin member forming the joining surface with the energy of the laser light. Laser welding generates no abrasion powder or burrs, causes little damage to the product, and furthermore, since the polyamide resin itself is a material having a relatively high laser transmittance, processing of polyamide resin products by laser welding technology has recently attracted attention.

[0005] The above-mentioned transmissive resin member is usually obtained by molding a light-transmissive resin composition. As such a light-transmissive resin composition, Patent Document 1 describes a resin composition obtained by blending (A) 100 parts by mass of a polyamide resin with (B) 1 to 150 parts by mass of a reinforcing filler having a refractive index at 23°C of 1.560 to 1.600, wherein at least one monomer constituting at least one of the (A) polyamide resins contains an aromatic ring, and a resin composition for laser welding is described. In the examples of Patent Document 1, a resin composition in which glass fibers and a colorant are blended with a blend of polyamide MXD6 and polyamide 66, or a blend of polyamide 6I / 6T and polyamide 6 is disclosed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Here, as the laser welding technology advances, there is an increasing demand for new materials. In particular, materials having excellent physical properties such as mechanical strength and low warpage and high light transmittance are in demand. An object of the present invention is to solve such problems, and to provide a transmissive resin composition for laser welding, a kit, a molded article, and a method for manufacturing a molded article, which are excellent in physical properties such as mechanical strength and low warpage and have high light transmittance.

Means for Solving the Problems

[0008] As a result of investigations by the inventors under the above problems, it has been found that the above problems can be solved by using glass flakes having a thickness of 0.1 to 2 μm as the reinforcing filler. Specifically, the above problems have been solved by the following means. <1> A transmissive resin composition for laser welding, comprising 10 to 120 parts by mass of glass flakes having a thickness of 0.1 to 2 μm and a light transmissive dye with respect to 100 parts by mass of a crystalline thermoplastic resin. <2> The resin composition according to <1>, wherein the light transmissive dye has a perylene skeleton. <3> The resin composition according to <1> or <2>, wherein the crystalline thermoplastic resin contains a polyamide resin. <4> The polyamide resin contained in <3> is composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, and 70 mol% or more of the structural unit derived from diamine is derived from xylylenediamine, and 70 mol% or more of the structural unit derived from dicarboxylic acid is derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 30 mol% or more of the structural unit derived from xylylenediamine is a structural unit derived from metaxylylenediamine. The resin composition according to <3>. <5> When the resin composition is formed into a molded product having a size of 60 mm × 60 mm × 1 mm in thickness, the warpage amount of the molded product is 1 mm or less. The resin composition according to any one of <1> to <4>; the warpage amount refers to the difference between the height of the highest part and the height of the lowest part of the test piece when the molded product is placed on a reference table. <6> The resin composition according to any one of <1> to <5>, wherein the crystalline thermoplastic resin contains a polyamide resin having a heat of crystallization of 0 to -1 mJ / mg when measured with a differential scanning calorimeter. <7> A kit having the resin composition according to any one of <1> to <6>, a light-absorbing resin composition containing a thermoplastic resin and a light-absorbing dye. <8> A molded product formed from the resin composition according to any one of <1> to <6> or the kit according to <7>. <9> A method for manufacturing a molded product, comprising laser-welding a molded product formed from the resin composition according to any one of <1> to <6> and a molded product formed from a light-absorbing resin composition containing a thermoplastic resin and a light-absorbing dye.

Advantages of the Invention

[0009] According to the present invention, it has become possible to provide a transmissive resin composition for laser welding, a kit, a molded article, and a method for manufacturing a molded article, which are excellent in physical properties such as mechanical strength and low warpage, and have a high light transmittance.

Brief Description of the Drawings

[0010]

Figure 1

Modes for Carrying Out the Invention

[0011] Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. It should be noted that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to the present embodiment. In this specification, “~” is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value. In this specification, various physical property values and characteristic values are those at 23° C. unless otherwise specified.

[0012] The transmissive resin composition for laser welding of the present embodiment (hereinafter sometimes simply referred to as “the resin composition of the present embodiment”) is characterized by containing 10 to 120 parts by mass of glass flakes having a thickness of 0.1 to 2 μm and a light-transmissive dye with respect to 100 parts by mass of a crystalline thermoplastic resin. By adopting such a configuration, it becomes possible to provide a transmissive resin composition for laser welding that is excellent in physical properties such as mechanical strength and low warpage and has a high light transmittance. Conventionally, in order to achieve mechanical strength and low warpage, etc., blending of inorganic fillers has been carried out. However, until now, it has not been known at all that the shape of the inorganic filler affects light transmittance. In the present invention, surprisingly, it has been found that by adopting glass flakes having a thickness of 0.1 to 2 μm as the inorganic filler, it is possible to improve the light transmittance in addition to mechanical strength and low warpage.

[0013] <Crystalline thermoplastic resin> The resin composition of this embodiment contains a crystalline thermoplastic resin. Examples of the crystalline thermoplastic resin include polyamide resins, polyacetal resins, polyester resins (preferably polybutylene terephthalate resins), etc. Polyamide resins and polybutylene terephthalate resins are preferred, and polyamide resins are more preferred. When using a crystalline polyamide resin, when molding a molded product, it can be cured faster. Also, when using a crystalline polyamide resin, the resulting resin composition tends to be excellent in oil resistance, grease resistance, lubricity, slidability, abrasion resistance, and friction resistance. A crystalline thermoplastic resin is one that has a "crystalline part" in which molecules are arranged regularly when the temperature of the resin drops to the crystallization temperature and solidifies.

[0014] In the resin composition of this embodiment, it is preferable that the crystalline thermoplastic resin occupies 30% by mass or more, more preferably 40% by mass or more, and even more preferably 45% by mass or more. Also, as the upper limit value of the content of the crystalline thermoplastic resin in the resin composition, it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. The resin composition of this embodiment may contain only one type of crystalline thermoplastic resin, or may contain two or more types. When containing two or more types, it is preferable that the total amount is within the above range.

[0015] <<Polyamide resin>> The polyamide resin used in this embodiment is not particularly defined, and known polyamide resins can be used. For example, regarding the polyamide resin, the descriptions in paragraphs 0011 to 0013 of JP-A-2011-132550 can be referred to. The polyamide resin used in this embodiment may be an aliphatic polyamide resin or a semi-aromatic polyamide resin, and is preferably a semi-aromatic polyamide resin.

[0016] Examples of aliphatic polyamide resins include polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide 1010, polyamide 1012, etc.

[0017] On the other hand, examples of semi-aromatic polyamide resins include those composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, and among the total structural units of the structural unit derived from diamine and the structural unit derived from dicarboxylic acid, 30 to 70 mol% are structural units containing an aromatic ring. Preferably, 40 to 60 mol% of the total structural units of the structural unit derived from diamine and the structural unit derived from dicarboxylic acid are structural units containing an aromatic ring. By using such a semi-aromatic polyamide resin, the mechanical strength of the obtained molded product can be increased. Examples of semi-aromatic polyamide resins include terephthalic acid-based polyamide resins (polyamide 6T, polyamide 9T), xylylenediamine-based polyamide resins described later, and the like.

[0018] The polyamide resin used in this embodiment preferably has at least one type composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, and 70 mol% or more of the structural unit derived from diamine is derived from xylylenediamine (preferably, 30 mol% or more of the structural unit derived from xylylenediamine is derived from metaxylylenediamine), and 70 mol% or more of the structural unit derived from dicarboxylic acid is derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms (hereinafter sometimes referred to as "xylylenediamine-based polyamide resin"). For the structural unit derived from diamine of the xylylenediamine-based polyamide resin, more preferably 75 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more, and still even more preferably 95 mol% or more is derived from xylylenediamine. For the structural unit derived from dicarboxylic acid of the xylylenediamine-based polyamide resin, more preferably 75 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more, and still even more preferably 95 mol% or more is derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms.

[0019] The xylylenediamine is preferably para-xylylenediamine and / or meta-xylylenediamine, more preferably contains at least meta-xylylenediamine, and even more preferably 30 mol% or more (preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more) of the xylylenediamine is meta-xylylenediamine. The xylylenediamine is more preferably 30 to 90 mol% (preferably 60 to 90 mol%) is meta-xylylenediamine and 70 to 10 mol% (preferably 40 to 10 mol%) is para-xylylenediamine. The total of meta-xylylenediamine and para-xylylenediamine is 100 mol% or less of the raw material diamine, and preferably 90 to 100 mol%.

[0020] Examples of diamines other than meta-xylylenediamine and para-xylylenediamine that can be used as the raw material diamine component of the xylylenediamine-based polyamide resin include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, etc., alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, bis(aminomethyl)tricyclodecane, etc., and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, bis(aminomethyl)naphthalene, etc. One kind or a mixture of two or more kinds can be used.

[0021] Preferred α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms for use as the raw material dicarboxylic acid component of xylylenediamine-based polyamide resins include, for example, aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, etc. One kind or a mixture of two or more kinds can be used. Among these, adipic acid or sebacic acid is more preferred because the melting point of the polyamide resin falls within an appropriate range for molding.

[0022] Examples of dicarboxylic acid components other than the above α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms include phthalic acid compounds such as isophthalic acid, terephthalic acid, orthophthalic acid, isomers of naphthalenedicarboxylic acid such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, etc. One kind or a mixture of two or more kinds can be used.

[0023] Note that the structural units derived from diamine and the structural units derived from dicarboxylic acid are the main components, but it goes without saying that other structural units are not completely excluded, and it may contain structural units derived from lactams such as ε-caprolactam and laurolactam, and aliphatic aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid. Here, the main component means that among the structural units constituting the xylylenediamine-based polyamide resin, the total number of the structural units derived from diamine and the structural units derived from dicarboxylic acid is the largest among all the structural units. In this embodiment, in the xylylenediamine-based polyamide resin, the total of the structural units derived from diamine and the structural units derived from dicarboxylic acid preferably accounts for 90% or more, and more preferably 95% or more of all the structural units.

[0024] The crystalline thermoplastic resin used in this embodiment preferably contains a polyamide resin having a heat of crystallization of 0 to -1 mJ / mg when measured with a differential scanning calorimeter, and more preferably contains a polyamide resin having a heat of crystallization of 0 to -0.8 mJ / mg. By using such a polyamide resin, crystallization proceeds effectively, and even when water is absorbed over time, a significant decrease in mechanical strength is less likely to occur. Here, the heat of crystallization means the value measured under the conditions described in the examples below.

[0025] As one embodiment of the resin composition of this embodiment, there is an embodiment that substantially does not contain a thermoplastic resin other than the polyamide resin. Substantially not containing means that the content of the thermoplastic resin other than the polyamide resin is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1% by mass or less of the resin composition of this embodiment.

[0026] In addition, as the polyacetal resin used in this embodiment, the description in paragraphs 0009 to 0012 of JP-A-2019-123836 can be referred to, and this content is incorporated herein. As the polybutylene terephthalate resin used in this embodiment, the description in paragraphs 0016 to 0024 of JP-A-2020-019950 can be referred to, and this content is incorporated herein.

[0027] <Glass flake> The resin composition of this embodiment contains 10 to 120 parts by mass of glass flakes having a thickness of 0.1 to 2 μm with respect to 100 parts by mass of the crystalline thermoplastic resin. By adopting such a configuration, it becomes possible to improve the light transmittance in addition to the mechanical strength and the flatness.

[0028] In this embodiment, the thickness of the glass flakes refers to the average thickness. The thickness of the glass flakes is preferably 0.3 μm or more, more preferably 0.4 μm or more, still more preferably 0.5 μm or more, even more preferably 0.6 μm or more. Also, the thickness of the glass flakes is preferably 1.8 μm or less, more preferably 1.6 μm or less, still more preferably 1.4 μm or less, even more preferably 1.2 μm or less, even more preferably 1.0 μm or less, and still even more preferably 0.8 μm or less. Here, the average thickness is measured by the following method. <<Measurement Method of Average Thickness>> Using a scanning electron microscope (SEM), the thickness of each of 100 or more glass flakes is measured, and the average value of the measured values is obtained. The sample stage of the scanning electron microscope is adjusted by a sample stage fine adjustment device so that the cross-section (thickness plane) of the glass flakes is perpendicular to the irradiation electron beam axis of the scanning electron microscope.

[0029] In this embodiment, the number average value of the aspect ratio of the glass flakes is preferably 3 to 20. The aspect ratio is also measured by the same method as the above-described measurement method of the average thickness.

[0030] For the glass composition of the above glass flakes, various glass compositions typified by A glass, C glass, D glass, R glass, S glass, E glass, etc. are applicable and are not particularly limited.

[0031] The resin composition of the present embodiment contains 10 to 120 parts by mass of glass flakes with a thickness of 0.1 to 2 μm with respect to 100 parts by mass of the crystalline thermoplastic resin. The glass flakes are preferably 20 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, and may be 45 parts by mass or more, 60 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more with respect to 100 parts by mass of the crystalline thermoplastic resin. Also, the glass flakes with a thickness of 0.1 to 2 μm are preferably 120 parts by mass or less, more preferably 115 parts by mass or less, still more preferably 110 parts by mass or less, and may be 105 parts by mass or less with respect to 100 parts by mass of the crystalline thermoplastic resin.

[0032] The glass flakes with a thickness of 0.1 to 2 μm preferably account for 10 to 60% by mass, more preferably 20 to 60% by mass, and may be 25 to 55% by mass in the resin composition of the present embodiment. The resin composition of the present embodiment may contain only one type of glass flakes with a thickness of 0.1 to 2 μm, or may contain two or more types. When containing two or more types, it is preferable that the total amount is within the above range. The resin composition of the present embodiment may or may not contain other inorganic fillers other than the glass flakes with a thickness of 0.1 to 2 μm. Examples of other inorganic fillers include fibrous, scaly, spherical, and acicular inorganic fillers, and examples of the components include glass, metal oxides, metal hydroxides, carbonates, sulfates, etc. An example of the resin composition of the present embodiment is a resin composition that substantially does not contain other inorganic fillers other than the glass flakes with a thickness of 0.1 to 2 μm. Substantially not containing means that the content of inorganic fillers other than the glass flakes with a thickness of 0.1 to 2 μm is 5% by mass or less of the total amount of inorganic fillers contained in the resin composition, preferably 3% by mass or less, and more preferably 1% by mass or less. Note that the inorganic fillers in the present embodiment do not include those corresponding to nucleating agents.

[0033] <Light-transmitting pigment> The resin composition of this embodiment contains a light-transmitting pigment. By containing the light-transmitting pigment, the resulting molded product can be given a color tone, and the appearance of the molded product can be improved. In particular, the color tone of the transparent resin member molded from the resin composition of this embodiment can be unified with that of the absorption resin member, the details of which will be described later, and the appearance of the resulting molded product (laser welded body) can be improved. The light-transmitting pigment used in this embodiment is usually a black pigment. Specifically, dyes having a structure selected from a nigrosine skeleton, a naphthalocyanine skeleton, an aniline black skeleton, a phthalocyanine skeleton, a porphyrin skeleton, a perinone skeleton, a quinoterylene skeleton, an azo skeleton, an anthraquinone skeleton, a pyrazolone skeleton, a squaric acid derivative skeleton, a perylene skeleton, a chromium complex, and an immonium skeleton are exemplified, and a pigment having a perylene skeleton is preferred. The light-transmitting pigment refers to, for example, a pigment that, when polyamide resin, 30% by mass of glass flakes, and 0.2% by mass of a pigment (thought to be a light-transmitting pigment) are blended to a total of 100% by mass and the light transmittance at a wavelength of 1060 nm is measured by the measurement method described in the examples below, has a transmittance of 2% or more. The light-transmitting pigment may be a dye or a pigment, but a pigment is preferred. Examples of commercially available products include e-BIND LTW-8731H and e-BIND LTW-8701H, which are colorants (pigments) manufactured by Orient Chemical Industries, Ltd., Plast Yellow 8000, Plast Red M 8315, and Oil Green 5602, which are colorants manufactured by Yumoto Chemical Co., Ltd., Macrolex Yellow 3G, Macrolex Red EG, and Macrolex Green 3, which are colorants manufactured by LANXESS, and Spectrasence K0087 (former: Lumogen® Black K0087, Lumogen Black FK4280), Spectrasence K0088 (former: Lumogen Black K0088, Lumogen Black FK4281), etc., which are colorants manufactured by BASF.

[0034] In the resin composition of this embodiment, the content of the light-transmissive pigment is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and may further be 0.08 part by mass or more, 0.1 part by mass or more, 0.15 part by mass or more, or 0.2 part by mass or more, per 100 parts by mass of the resin composition. Also, the upper limit of the content of the light-transmissive pigment is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, still more preferably 1.0 part by mass or less, and may also be 0.8 part by mass or less, 0.5 part by mass or less, 0.4 part by mass or less, or 0.3 part by mass or less, per 100 parts by mass of the resin composition. The resin composition may contain only one kind of light-transmissive pigment or may contain two or more kinds. When two or more kinds are contained, it is preferable that the total amount is within the above range. Further, the transmissive resin composition for laser welding of this embodiment preferably does not substantially contain carbon black. "Not substantially containing" means, for example, 0.0001% by mass or less of the resin composition.

[0035] <Nucleating agent> The resin composition of this embodiment may contain a nucleating agent. The nucleating agent is not particularly limited as long as it is unmelted during melt processing and can become nuclei of crystals during the cooling process. Among them, talc and calcium carbonate are preferable, and talc is more preferable. The number average particle diameter of the nucleating agent preferably has a lower limit of 0.1 μm or more, more preferably 1 μm or more, and still more preferably 3 μm or more. The number average particle diameter of the nucleating agent preferably has an upper limit of 40 μm or less, more preferably 30 μm or less, still more preferably 28 μm or less, even more preferably 15 μm or less, and still even more preferably 10 μm or less.

[0036] The ratio of the nucleating agent in the resin composition of this embodiment is preferably 0.01 to 1% by mass, more preferably 0.1% by mass or more, and more preferably 0.5% by mass or less. The resin composition of the present embodiment may contain only one type of nucleating agent or two or more types of nucleating agents. When two or more types are contained, it is preferable that the total amount is within the above range.

[0037] <Copper compound> The resin composition of the present embodiment may contain a copper compound. By using a copper compound, significantly excellent heat aging resistance can be achieved. Examples of the copper compound used in the present embodiment include copper halides (e.g., copper iodide, copper bromide, copper chloride) and copper acetate, and are preferably selected from cuprous iodide, cupric iodide, cuprous bromide, cupric bromide, cuprous acetate, cupric acetate, cuprous chloride, and cupric chloride, and more preferably selected from cuprous iodide, cuprous acetate, and cuprous chloride. Further, the copper compound is preferably used in combination with an alkali metal halide described later. When a copper compound and an alkali metal halide are combined, it is preferably a mixture of copper compound:alkali metal halide in a mass ratio of 1:1 to 1:15, more preferably a mixture of 1:1 to 1:5, and even more preferably a mixture of 1:2 to 1:4. Regarding the case of combining a copper compound and an alkali metal halide, the descriptions in paragraphs 0046 to 0048 of Japanese Patent Application Laid-Open No. 2013-513681 can also be referred to, and these contents are incorporated herein.

[0038] The proportion of the copper compound in the resin composition of the present embodiment is preferably 0.01 to 1% by mass, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and more preferably 0.5% by mass or less. The resin composition of the present embodiment may contain only one type of copper compound or two or more types of copper compounds. When two or more types are contained, it is preferable that the total amount is within the above range.

[0039] <Alkali metal halide> The alkali metal halide used in this embodiment refers to a halide of an alkali metal. As the alkali metal, potassium and sodium are preferred, and potassium is more preferred. As the halogen atom, iodine, bromine, and chlorine are preferred, and iodine is more preferred. Specific examples of the alkali metal halide used in this embodiment include potassium iodide, potassium bromide, potassium chloride, and sodium chloride, and potassium iodide is preferred.

[0040] The proportion of the alkali metal halide in the resin composition of this embodiment is preferably 0.01 to 1% by mass, more preferably 0.1% by mass or more, and still more preferably 0.5% by mass or less. The resin composition of this embodiment may contain only one kind or two or more kinds of alkali metal halides. When two or more kinds are contained, the total amount is preferably within the above range.

[0041] <Release agent> The resin composition of this embodiment preferably contains a release agent. By containing a release agent, when molding using a mold such as injection molding, the releasability from the mold can be improved. The release agent preferably contains at least one selected from amide waxes and fatty acid metal salts, and more preferably contains a fatty acid metal salt.

[0042] Examples of the amide wax include carboxylic acid amide wax and bisamide wax, and carboxylic acid amide wax is preferred. The carboxylic acid amide wax is obtained, for example, by a dehydration reaction of a mixture of a higher aliphatic monocarboxylic acid and a polybasic acid with a diamine compound. As the higher aliphatic monocarboxylic acid, a saturated aliphatic monocarboxylic acid and a hydroxycarboxylic acid having 16 or more carbon atoms are preferable, and examples thereof include palmitic acid, stearic acid, behenic acid, montanic acid, 12-hydroxystearic acid, and the like. As the polybasic acid, a carboxylic acid having two or more carboxyl groups, for example, aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, sebacic acid, pimelic acid, azelaic acid, aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, cyclohexyl succinic acid, and the like can be mentioned. As the diamine compound, for example, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, metaxylylenediamine, tolylenediamine, paraxylylenediamine, phenylenediamine, isophoronediamine, and the like can be mentioned.

[0043] In the carboxylic acid amide wax of the present embodiment, the softening point can be arbitrarily adjusted by changing the mixing ratio of the polybasic acid with respect to the higher aliphatic monocarboxylic acid used in its production. The mixing ratio of the polybasic acid is preferably in the range of 0.18 to 1 mol with respect to 2 mol of the higher aliphatic monocarboxylic acid. Further, the amount of the diamine compound used is preferably in the range of 1.5 to 2 mol with respect to 2 mol of the higher aliphatic monocarboxylic acid, and varies according to the amount of the polybasic acid used.

[0044] Examples of the bisamide wax include compounds of a diamine compound and a fatty acid such as N,N'-methylenebisstearic acid amide and N,N'-ethylenebisstearic acid amide, or dioctadecyl dibasic acid amides such as N,N'-dioctadecyl terephthalic acid amide.

[0045] As the fatty acid metal salt, a metal salt of a long-chain fatty acid having 16 to 36 carbon atoms is preferred. For example, metal stearates such as calcium stearate, zinc stearate, aluminum stearate, sodium stearate, lithium stearate, etc., and metal montanates such as calcium montanate, sodium montanate, etc. are mentioned, and metal montanates are preferred.

[0046] As the release agent, in addition to the above, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15,000, polysiloxane-based silicone oils, ketone waxes, etc. are also exemplified. Details of the release agent can refer to the descriptions in paragraphs 0055 to 0061 of JP-A-2018-095706 and paragraphs 0022 to 0027 of JP-A-2019-108526, and the contents of these are incorporated herein.

[0047] The content of the release agent in the resin composition of this embodiment is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more in the resin composition. By setting the lower limit value or more, the releasability tends to be further improved. Also, the content of the release agent is preferably 3% by mass or less, more preferably 2% by mass or less, further preferably 1% by mass or less, still more preferably 0.8% by mass or less, and even more preferably 0.6% by mass or less. The resin composition of this embodiment may contain only one kind of release agent or two or more kinds. When two or more kinds are contained, the total amount is preferably within the above range.

[0048] <Other components> The resin composition of this embodiment may contain other components as long as it does not deviate from the gist of this embodiment. Such additives include fillers other than glass flakes with a thickness of 0.1 to 2 μm, light stabilizers, antioxidants, ultraviolet absorbers, fluorescent brighteners, anti-dripping agents, antistatic agents, antifogging agents, antiblocking agents, fluidity improvers, plasticizers, dispersants, antiviral agents, antibacterial agents, flame retardants, and the like. These components may be used alone or in combination of two or more. As the flame retardant, a phosphorus-based flame retardant is preferred. Examples of the phosphorus-based flame retardant include phosphazene-based flame retardants, phosphinate-based flame retardants, and diphosphinate-based flame retardants. In addition, for the resin composition of this embodiment, the content of the crystalline thermoplastic resin (preferably a polyamide resin), glass flakes with a thickness of 0.1 to 2 μm, and light-transmitting dyes, and further, nucleating agents, copper compounds, alkali metal halides, mold release agents, and other additives is adjusted so that the total of each component is 100% by mass. In this embodiment, an aspect is exemplified in which the total of the crystalline thermoplastic resin, glass flakes with a thickness of 0.1 to 2 μm, and optionally added nucleating agents, copper compounds, alkali metal halides, and mold release agents accounts for 99% by mass or more of the resin composition.

[0049] <Physical properties of the resin composition> When formed into a molded product, the resin composition of this embodiment preferably has little warpage. Specifically, when the resin composition of this embodiment is formed into a molded product with a size of 60 mm × 60 mm × 1 mm in thickness, the warpage amount of the molded product is preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.9 mm or less. The warpage amount refers to the difference between the height of the highest part and the height of the lowest part of the test piece when the molded product is placed on the reference table. Details follow the description of the examples described later. The ideal lower limit value of the warpage amount is 0 mm, but 0.05 mm or more is practical.

[0050] The resin composition of this embodiment is preferably formed into an ISO tensile test piece with a thickness of 4 mm and has a high flexural strength measured in accordance with ISO 178. Specifically, the flexural strength is preferably 200 MPa or more. Also, the upper limit is preferably as high as possible, but for example, 500 MPa or less is practical. The resin composition of this embodiment is preferably formed into an ISO tensile test piece with a thickness of 4 mm and has a high flexural modulus measured in accordance with ISO 178. Specifically, the flexural modulus is preferably 9000 MPa or more. Also, the upper limit is preferably as high as possible, but for example, 20000 MPa or less is practical.

[0051] <Method for producing resin composition> The method for producing the resin composition of this embodiment is not particularly limited, but a method using a single-screw or twin-screw extruder having a facility capable of degassing from a vent port as a kneader is preferred. The above crystalline thermoplastic resin component, glass flakes with a thickness of 0.1 to 2 μm, light-transmissive pigment, and other additives blended as required may be supplied to the kneader all at once, or other compounding components may be sequentially supplied to the crystalline thermoplastic resin. Inorganic fillers such as glass flakes with a thickness of 0.1 to 2 μm are preferably supplied from the middle of the extruder in order to suppress crushing during kneading. Also, two or more components selected from each component may be premixed and kneaded. In this embodiment, the light-transmissive pigment is a thermoplastic resin such as polyamide 6 or polyamide 66. After preparing a masterbatch in advance, it may be kneaded with other components (such as thermoplastic resins) to adjust the resin composition in this embodiment.

[0052] <Method for producing molded article> The method for producing a molded article using the resin composition of this embodiment is not particularly limited, and molding methods generally used for thermoplastic resins, that is, injection molding, blow molding, extrusion molding, press molding, etc. can be applied. The resin composition of this embodiment is particularly suitable for a method of molding using a mold. Furthermore, it is suitable for a molding method of cooling by a mold.

[0053] The kit of this embodiment has the resin composition of this embodiment and a light-absorbing resin composition containing a thermoplastic resin and a light-absorbing dye. The kit of this embodiment is preferably used for manufacturing a molded article by laser welding. That is, the resin composition contained in the kit serves as a light-transmissive resin composition, and the molded article formed by molding the light-transmissive resin composition becomes a transmissive resin member for laser light during laser welding. On the other hand, the molded article formed by molding the light-absorbing resin composition becomes an absorbing resin member for laser light during laser welding.

[0054] <<Light-absorbing resin composition>> The light-absorbing resin composition used in this embodiment contains a thermoplastic resin (preferably a crystalline thermoplastic resin) and a light-absorbing dye. Examples of the thermoplastic resin include polyamide resins, olefin resins, vinyl resins, styrene resins, acrylic resins, polyphenylene ether resins, polyester resins, polycarbonate resins, polyacetal resins, etc. Particularly, polyamide resins, polyacetal resins, and polyester resins (preferably polybutylene terephthalate resins) are preferred from the viewpoint of good compatibility with the resin composition, and polyamide resins are more preferred. Also, the thermoplastic resin may be one kind or two or more kinds. As the polyamide resin used in the light-absorbing resin composition, the type and the like are not defined, but the above xylylenediamine-based polyamide resin is preferred. The light-absorbing resin composition may also contain an inorganic filler. Examples of the inorganic filler include fillers capable of absorbing laser light such as glass flakes (particularly glass flakes having a thickness of 0.1 to 2 μm), glass fibers, carbon fibers, and inorganic powders coated with a material that absorbs laser light. A light-absorbing pigment refers to a pigment that is less permeable to laser light during laser welding than a light-transmitting pigment. Examples of light-absorbing pigments include those having a maximum absorption wavelength in the range of the laser light wavelength to be irradiated, for example, in the range of wavelengths from 800 nm to 1100 nm. As an embodiment of the light-absorbing pigment in the present embodiment, a pellet obtained by blending 0.07 parts by mass of a pigment with respect to 100 parts by mass of a polyamide resin (MP10 synthesized in the examples described later) and melt-kneading at a set temperature of 280°C of an extruder, and having a light transmittance of less than 2% at a wavelength of 1060 mm measured by the method described in the examples described later is mentioned. The mold temperature at this time is 110°C. Specific examples of the light-absorbing pigment include inorganic pigments (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), organic pigments (yellow pigments, orange pigments, red pigments, blue pigments, green pigments, etc.). Among them, inorganic pigments are generally preferred because of their strong hiding power, black pigments are more preferred, and carbon black is even more preferred. These light-absorbing pigments may be used in combination of two or more. The content of the light-absorbing pigment is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

[0055] In the kit of the present embodiment, it is preferable that 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95 to 100% by mass of the components excluding the light-transmitting pigment in the laser-welding-permeable resin composition and the components excluding the light-absorbing pigment in the light-absorbing resin composition are common.

[0056] <<Laser Welding Method>> Next, the laser welding method will be described. In the present embodiment, a molded article (transparent resin member) formed from the laser-welding transparent resin composition of the present embodiment and a molded article (absorbing resin member) formed from the light-absorbing resin composition are laser-welded to manufacture a molded article. By laser welding, the transparent resin member and the absorbing resin member can be firmly welded without using an adhesive. The shape of the members is not particularly limited, but since the members are joined by laser welding for use, they usually have a shape with at least a surface contact portion (plane, curved surface). In laser welding, the laser light transmitted through the transparent resin member is absorbed by the absorbing resin member, melted, and both members are welded. Here, the thickness of the member through which the laser light passes (the thickness in the laser transmission direction in the portion where the laser light passes) can be appropriately determined in consideration of the application, the composition of the resin composition, and the like. For example, it is 5 mm or less, preferably 4 mm or less. The lower limit of the thickness of the member through which the laser passes is, for example, 0.01 mm or more.

[0057] The laser light source used for laser welding can be determined according to the light absorption wavelength of the light-absorbing dye, and a laser in the wavelength range of 800 to 1100 nm is preferred. For example, a semiconductor laser or a fiber laser can be used.

[0058] More specifically, for example, when welding a transparent resin member and an absorbing resin member, first, the welding portions of both are brought into contact with each other. At this time, surface contact is desirable for the welding portions of both, and they may be a combination of planes, curved surfaces, or a plane and a curved surface. Next, laser light is irradiated from the transparent resin member side. At this time, a lens may be used to condense the laser light at the interface between the two if necessary. The condensed beam passes through the transparent resin member, is absorbed near the surface of the absorbing resin member, generates heat, and melts. Next, the heat is also transmitted to the transparent resin member by heat conduction and melts, forming a molten pool at the interface between the two. After cooling, the two are joined. The molded product (laser welded body) in which the transparent resin member and the absorbent resin member are welded in this way has high welding strength. Note that the molded product in the present embodiment includes, in addition to the finished product and parts, members that form a part of these.

[0059] The molded product obtained by laser welding in this embodiment has good mechanical strength, high welding strength, and little damage to the resin due to laser light irradiation. Therefore, it can be applied to various uses, for example, various storage containers, electrical and electronic equipment parts, office automation (OA) equipment parts, household electrical appliance parts, mechanical mechanism parts, vehicle mechanism parts, etc. In particular, it can be suitably used for food containers, medicine containers, oil and fat product containers, vehicle hollow parts (various tanks, intake manifold parts, camera housings, etc.), vehicle electrical parts (various control units, ignition coil parts, etc.), motor parts, various sensor parts, connector parts, switch parts, breaker parts, relay parts, coil parts, transformer parts, lamp parts, etc. In particular, the resin composition and kit of the present embodiment are suitable for vehicle hollow parts such as in-vehicle camera housings.

Examples

[0060] The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. When the measuring instruments etc. used in the examples are difficult to obtain due to obsolescence etc., measurement can be performed using other instruments having equivalent performance.

[0061] Raw materials MP10: A polyamide resin composed of metaxylylenediamine, paraxylylenediamine (MP molar ratio: 7:3), and sebacic acid, synthesized according to the description in paragraph 0071 of JP-A-2018-119043. The heat of crystallization measured by the following method was -0.5 mJ / mg. MP6: A polyamide resin composed of metaxylylenediamine, paraxylylenediamine (molar ratio: 7:3), and adipic acid, synthesized according to the description in paragraph 0072 of JP-A-2018-119043. The heat of crystallization measured by the following method was -0.5 mJ / mg. PA66: Polyamide 66, manufacturer: INVISTA Nylon Polymer, Invista U4800. The heat of crystallization measured by the following method was -0.9 mJ / mg. The heat of crystallization was measured using a differential scanning calorimeter as follows. <Heat of crystallization> For the synthesized resin pelletized and formed into a test piece (60×60×1 mm thick) at a cylinder temperature of 280°C, the heat of crystallization was measured at a heating rate of 10°C / min and from 30 to 300°C using differential scanning calorimetry (DSC). The cylinder temperature was 260°C when MP10 was used as the polyamide resin, 280°C when MP6 was used, and 280°C when PA66 was used. The mold surface temperature was 110°C when MP10 was used as the polyamide resin, 130°C when MP6 was used, and 90°C when PA66 was used. Also, DSC7020 manufactured by Hitachi High-Tech Science Corporation was used for DSC. The unit of the heat of crystallization was shown as mJ / mg.

[0062] Talc: manufactured by Hayashi Kasei, #5000S Cuprous iodide: manufactured by Nippon Chemical Industry Co., Ltd., cuprous iodide Potassium iodide: manufactured by Fujifilm Wako Pure Chemical Corporation Zinc(II) stearate: manufactured by Fujifilm Wako Pure Chemical Corporation Release agent: manufactured by Nitto Kasei Kogyo Co., Ltd., CS8CP, calcium montanate Light-transmissive dye: manufactured by BASF Color & Effect Japan Co., Ltd., Lumogen (registered trademark) Black K 0088 (former Lumogen Black FK 4281), a pigment having a perylene skeleton Inorganic filler Glass fiber: manufactured by Nippon Electric Glass Co., Ltd., ECS03T-211H Fine Flakes: manufactured by Nippon Sheet Glass Co., Ltd., Micro Glass Fine Flakes MEG160FY-M06, average thickness of about 0.7 μm, aspect ratio of 3 to 20

[0063] Examples 1 to 6, Comparative Examples 1 to 6 Pellets (resin compositions) for forming a light transmission member described in Table 1 or 2 below were produced. Specifically, for each of the components shown in Table 1 or 2 below, components other than the inorganic fillers (glass fiber and fine flakes) were weighed at the ratios shown in Table 1 or 2 (unit: parts by mass), dry blended, and then charged from the screw root of a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., TEM26SS) using a twin-screw type cassette weighing feeder (manufactured by Kubota Corporation, CE-W-1-MP). For the inorganic fillers, a vibratory cassette weighing feeder (manufactured by Kubota Corporation, CE-V-1B-MP) was used to charge them into the above-mentioned twin-screw extruder from the side of the extruder, and they were melt-kneaded with the resin components, etc., to obtain pellets (resin compositions) for forming a light transmission member. After drying the pellets for forming a light transmission member obtained above at 120 °C for 4 hours, test pieces for a light transmission member (60 mm × 60 mm × 1.0 mm thick) were produced using an injection molding machine (NEX140III-12EG manufactured by Nissei Plastic Industrial Co., Ltd.). Also, after drying the pellets obtained by the above manufacturing method at 120 °C for 4 hours, ISO tensile test pieces (4 mm thick) were injection molded using an injection molding machine (NEX140III-12EG manufactured by Nissei Plastic Industrial Co., Ltd.). During molding, the cylinder temperature was 260 °C when MP10 was used as the polyamide resin, 280 °C when MP6 was used, 280 °C when PA66 was used, and the mold temperature was 130 °C (MP6), 110 °C (MP10), 90 °C (PA66) according to the type of polyamide resin which is the main component of the resin component.

[0064] <Flexural Strength and Flexural Modulus> In accordance with ISO178, using the above ISO tensile test pieces (4 mm thick), the flexural strength (unit: MPa) and flexural modulus (unit: MPa) were measured at a temperature of 23 °C.

[0065] <Warpage evaluation> The test piece for the light transmission member (60 mm × 60 mm × 1.0 mm thick) obtained above was placed on the reference table, and the height of the highest part (Max height, unit: mm) and the height of the lowest part of the test piece (Min height, unit: mm) were measured respectively using a three-dimensional shape measuring machine, and the difference was calculated. Specifically, as shown in FIG. 1, with the height of the reference table 1 being 0 mm, when the test piece 2 for the light transmission member was placed, the difference between the highest part 3 and the lowest part (usually the end of the test piece) among the heights was measured as the warp 4. As the three-dimensional shape measuring machine, VR-3200, manufactured by Keyence Corporation, was used.

[0066] <Light transmittance> For the test piece for the light transmission member (60 mm × 60 mm × 1.0 mm thick) obtained above, the light transmittance at a wavelength of 1060 nm was measured. The unit was shown as %. The measurement of the light transmittance was performed using LMT-F1LC-PA, manufactured by Kobus Electric Co., Ltd.

[0067]

Table 1

[0068]

Table 2

[0069] As is clear from the above results, the molded products formed from the resin composition of the present invention had a high light transmittance (Examples 1 to 6). On the other hand, in Examples 1 to 6, when an equal amount of glass fiber was blended respectively, the light transmittance was low (Comparative Examples 1 to 6). From these results, it was found that when glass flakes with a thickness of 0.1 to 2 μm were used instead of glass fiber as the inorganic filler, the light transmittance was improved. Furthermore, the molded products formed from the resin composition of the present invention could maintain high various mechanical strengths, and furthermore, the warpage could be effectively suppressed.

[0070] Regarding the resin composition described in Example 1, without blending a light-transmissive dye, instead, 3 parts by mass of a carbon black masterbatch (carbon black #45 manufactured by Mitsubishi Chemical Corporation) was blended as a light-absorbing dye, and in the same manner, pellets for forming an absorption resin member were obtained. Using the pellets for forming a light-transmissive member obtained in Example 1 and the pellets for forming an absorption resin member, laser welding was performed according to the descriptions in paragraphs 0072 and 0073 of JP-A-2018-168346 and FIG. 1. It was confirmed that laser welding was appropriately performed.

Explanation of Signs

[0071] 1 Base 2 Test piece for light-transmissive member 3 Highest part in height 4 Warpage

Claims

1. A transmissive resin composition for laser welding, comprising 10 to 120 parts by mass of glass flakes having a thickness of 0.1 to 0.8 μm and a light-transmissive dye with respect to 100 parts by mass of a crystalline thermoplastic resin, wherein the crystalline thermoplastic resin includes a polyamide resin, and the content of thermoplastic resins other than the polyamide resin is 5% by mass or less of the resin composition.

2. The resin composition according to claim 1, wherein the light-transmissive dye has a perylene skeleton.

3. The resin composition according to claim 1 or 2, wherein the polyamide resin is composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, at least 70 mol% of the structural unit derived from diamine is derived from xylylenediamine, at least 70 mol% of the structural unit derived from dicarboxylic acid is derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and at least 30 mol% of the structural unit derived from xylylenediamine is a structural unit derived from metaxylylenediamine.

4. The resin composition according to any one of claims 1 to 3, wherein when the resin composition is formed into a molded article having a size of 60 mm × 60 mm × 1 mm thickness, the warpage amount of the molded article is 1 mm or less; the warpage amount refers to the difference between the height of the highest part and the height of the lowest part of the test piece when the molded article is placed on a reference table.

5. The resin composition according to any one of claims 1 to 4, wherein the crystalline thermoplastic resin includes a polyamide resin having a heat of crystallization of 0 to -1 mJ / mg when measured by a differential scanning calorimeter.

6. A kit comprising the resin composition according to any one of claims 1 to 5, a light-absorbing resin composition containing a thermoplastic resin and a light-absorbing dye.

7. A molded article formed from the resin composition according to any one of claims 1 to 5 or the kit according to claim 6.

8. A method for manufacturing a molded article, comprising laser-welding a molded article formed from the resin composition according to any one of claims 1 to 5 and a molded article formed from a light-absorbing resin composition containing a thermoplastic resin and a light-absorbing dye.

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