JP4685439B2 - Laser welding resin composition and molded body - Google Patents

Description

  The present invention relates to a resin composition for laser welding for bonding to a resin molded body that is an object to be bonded using welding by laser light irradiation, and a bonded composite molded body.

  As a method of bonding resin members, a method of bonding resin members via an adhesive or a pressure-sensitive adhesive is known, but welding that directly bonds resin members from the viewpoints of recyclability and shortening of work processes is known. Attention has been focused on the joining method by the above. Among welding methods by welding, the laser welding method using laser light irradiation is less susceptible to heat and vibration than the hot plate welding method, ultrasonic welding method, and vibration welding method, and the shape of the resin molded product In recent years, it has attracted attention because it has the advantage that it can be joined efficiently without greatly depending on the above. However, in the laser welding method, when the resin molded body is welded, the resin member on the laser transmission side is required to have high transparency with respect to the laser beam, and usually has no transmittance of 20% or more, at least 10% or more. , Sufficient welding cannot be obtained.

  On the other hand, polyester resins represented by polyethylene terephthalate (PET) resins and polybutylene terephthalate (PBT) resins are excellent in properties such as heat resistance, chemical resistance, electrical properties, mechanical properties, and moldability. Therefore, it is used for a wide range of applications such as home appliances, office automation (OA) devices, and automobile parts. In such laser welding of polyester resins, polyester resins having high crystallinity (for example, PBT) have low laser light transmittance, and are sufficiently welded when used as a resin member on the laser transmission side. Therefore, it is necessary to reduce the thickness of the member. Furthermore, a member made of a polyester-based resin is liable to cause sinks and warpage, and has insufficient impact resistance.

  Therefore, Japanese Patent Application Laid-Open No. 2003-292752 (Patent Document 1) describes PBT resin (A), polycarbonate resin, acrylonitrile-styrene copolymer, polyphenylene oxide, styrene resin, acrylic resin, polyethersulfone, polyarylate. And at least one resin (B) selected from PET, and the ratio of the resin (B) is 1 to 50% by weight with respect to the total of the PBT resin (A) and the resin (B) A welding resin composition is disclosed.

  However, even this resin composition does not have sufficient mechanical properties such as rigidity. For example, when the polycarbonate mentioned as a preferable resin is mix | blended, fluidity | liquidity falls. In addition, polycarbonate and PBT are liable to undergo transesterification, resulting in instability in resin characteristics, slowing down the crystallization rate, and easy occurrence of sink marks and warpage. Further, when acrylonitrile-styrene resin (AS resin) is blended, the impact resistance is lowered and becomes brittle.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-262961 (Patent Document 2) discloses a rubber reinforced resin (A1) obtained by polymerizing a vinyl monomer in the presence of a rubbery polymer (a), or this rubber reinforced resin. A wavelength of 808 nm when formed as a test piece having a thickness of 4 mm, comprising a thermoplastic resin (A) containing a composition (A2) of a resin (A1) and a (co) polymer (b) of a vinyl monomer. A laser welding molding material having a light transmittance of 5% or more is disclosed.

However, when a rubber reinforced resin such as ABS resin is used, not only the heat resistance, chemical resistance and molding processability are lowered, but also welding is not sufficient as compared with the polyester resin. Furthermore, depending on the type of rubber-reinforced resin, gas is generated by laser welding, and the weldability decreases.
Japanese Patent Laying-Open No. 2003-292752 (Claim 1, paragraph number [0020]) Japanese Patent Laying-Open No. 2004-262961 (Claim 1)

  Accordingly, an object of the present invention is to provide a resin composition that can be firmly bonded to a bonded body (resin molded body) by laser light irradiation and that is excellent in various resin characteristics, a molded body thereof, and the molding thereof. An object of the present invention is to provide a laser welding method using a body and a composite molded body obtained by the method.

  Another object of the present invention is to provide a laser-welded resin composition that can be strongly bonded to an object to be bonded even when a polyester resin is used, and that can improve impact resistance, a molded body thereof, and the molding thereof. An object of the present invention is to provide a laser welding method using a body and a composite molded body obtained by the method.

  Still another object of the present invention is to provide a laser welding resin composition having high heat resistance, low gas generation amount, and capable of being strongly bonded to an object to be bonded even if it contains a rubber-containing styrene resin. And a molded body thereof, a laser welding method using the molded body, and a composite molded body obtained by the method.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention can combine the polyester resin and the styrene resin containing the rubber component at a specific ratio, and can be firmly laser-welded, and various It was found that the resin characteristics were also excellent, and the present invention was completed.

That is, the laser welding resin composition of the present invention is a resin composition for constituting a molded body that can be bonded to a resin molded body by irradiation with laser light, and the polyester resin (A), It is comprised with the styrene-type resin (B) which contains a rubber component 1 to 60weight%. The styrene resin (B) may contain, for example, a rubber component at a ratio of about 3 to 30% by weight. Furthermore, the ratio of sodium, chlorine and sulfate ions contained in the styrene resin (B) may be 10 ppm or less in total. The styrene resin (B) is a rubber graft styrene resin (for example, acrylonitrile-butadiene rubber-styrene resin, acrylonitrile-acrylic) containing an acrylic monomer and / or a vinyl cyanide monomer as a structural unit. Rubber-styrene resin, acrylonitrile-ethylene / propylene rubber-styrene resin, methyl methacrylate-butadiene rubber-styrene resin, methyl methacrylate-acrylonitrile-butadiene rubber-styrene resin, and the like. The polyester resin (A) may be a polyester resin containing at least a C _2-4 alkylene arylate unit (for example, a butylene terephthalate unit). The ratio (weight ratio) between the polyester resin (A) and the styrene resin (B) is, for example, the former / the latter = about 90/10 to 10/90. In the resin composition of the present invention, the ratio of the organic acid contained in the composition may be 2000 ppm or less.

  The molded body comprised with the said resin composition is also contained in this invention. The present invention also includes a composite molded body in which a first molded body composed of the resin composition and a second molded body composed of a thermoplastic resin are joined by laser welding. In this composite molded body, the molded body composed of the resin composition of the present invention is excellent in laser transmittance, and may be used as a transmissive member, for example. Furthermore, the present invention also includes a method of joining the first molded body composed of the resin composition and the second molded body composed of the thermoplastic resin by irradiating with laser light.

  In the present invention, since the resin composition for laser welding is composed of a polyester-based resin and a specific rubber-containing styrene-based resin, it can be firmly bonded to an object to be bonded by laser light irradiation, and various resins Excellent characteristics. In addition, despite the use of a polyester-based resin, it can be strongly bonded to the object to be bonded and the impact resistance can be improved. Furthermore, even if it contains a rubber-containing styrene resin, the heat resistance is high, the amount of gas generation is small, and it can be firmly bonded to the object to be bonded.

[Laser welding resin composition]
The laser welding resin composition of the present invention comprises a polyester resin (A) and a styrene resin (B) containing 1 to 60% by weight of a rubber component.

(A) Polyester resin The polyester resin (A) includes aromatic polyester resins and aliphatic polyester resins. As the polyester resin, an aromatic polyester resin (for example, a polyalkylene arylate resin or a saturated aromatic polyester resin) is usually used.

  The aromatic polyester resin can be obtained by a polycondensation reaction between a dicarboxylic acid component containing an aromatic dicarboxylic acid or an ester thereof and a diol component.

Examples of the aromatic dicarboxylic acid include aromatic dicarboxylic acids having about 8 to 14 carbon atoms such as phthalic acid, isophthalic acid, terephthalic acid and naphthalenedicarboxylic acid, or esters thereof (for example, C _1-3 such as methyl ester). Alkyl ester, etc.). These aromatic dicarboxylic acids can be used alone or in combination of two or more. Of these aromatic dicarboxylic acids, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, particularly terephthalic acid is preferred.

  In addition to aromatic dicarboxylic acids, dicarboxylic acid components include aliphatic dicarboxylic acids (for example, saturated aliphatic dicarboxylic acids having about 2 to 14 carbon atoms such as adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, and maleic acid. , Unsaturated aliphatic dicarboxylic acids such as fumaric acid and itaconic acid, unsaturated aliphatic tricarboxylic acids such as aconitic acid), alicyclic dicarboxylic acids (eg, tetrahydrophthalic acid, tetrahydroisophthalic acid, tetrahydroterephthalic acid, etc.) May be included.

Examples of the diol component include aliphatic diols (e.g., ethylene glycol, trimethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol and the like having about 2 to 12 carbon atoms). Aliphatic glycols and unsaturated aliphatic glycols such as 1,4-butenediol), and alicyclic diols (for example, 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol). These diol components can be used alone or in combination of two or more. Among these diol components, C _2-4 alkanediols such as ethylene glycol and 1,4-butanediol, particularly 1,4-butanediol is preferable.

Examples of the aromatic polyester-based resin include poly C _2-4 alkylene terephthalates such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); poly C _2-4 alkylene naphthalates corresponding to the polyalkylene terephthalate (for example, Examples thereof include polyethylene naphthalate); poly 1,4-cyclohexyldimethylene terephthalate (PCT) and the like.

The aromatic polyester resin may be a copolyester containing an alkylene arylate unit as a main component (for example, 50% by weight or more). Examples of the copolymer component include ethylene glycol, propylene glycol, butanediol, and hexanediol. Examples thereof include C _2-6 alkylene glycol, poly C _2-4 alkylene glycol, asymmetric aromatic dicarboxylic acids such as phthalic acid and isophthalic acid, or acid anhydrides thereof, and aliphatic dicarboxylic acids such as adipic acid. Further, a branched chain structure may be introduced into the linear polyester using a small amount of polyol and / or polycarboxylic acid.

  These polyester resins can be used alone or in combination of two or more.

In the present invention, among these polyester resins, polyester resins containing at least C _2-4 alkylene arylate units (for example, C _2-4 alkylene terephthalate units such as ethylene terephthalate and butylene terephthalate, particularly butylene terephthalate units) are preferable. . Specifically, as the polyester resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), a copolyester containing an ethylene terephthalate unit, a copolyester containing a butylene terephthalate unit, or a combination thereof is preferable. In particular, in the present invention, a resin composition having high weldability can be obtained even when PBT having a low laser transmittance is used.

(B) Rubber-containing styrenic resin The rubber-containing styrenic resin (B) has a rubbery polymer (rubber component) formed in a matrix composed of styrenic resin by copolymerization (graft polymerization, block polymerization, etc.). It may be a polymer dispersed in the form of particles. Usually, at least an aromatic vinyl monomer is used in the presence of a rubber-like polymer in the usual manner (bulk polymerization, bulk suspension polymerization, solution polymerization, emulsion polymerization, etc. ) Is a graft copolymer (rubber-grafted styrene polymer) obtained by polymerization.

  The styrene resin is a homopolymer or a copolymer containing an aromatic vinyl monomer as a main structural unit. Examples of the aromatic vinyl monomer for forming the styrene-based resin include styrene, alkyl-substituted styrene (for example, vinyl toluene, vinyl xylene, p-ethyl styrene, p-isopropyl styrene, butyl styrene, pt- Butyl styrene, etc.), halogen-substituted styrene (for example, chlorostyrene, bromostyrene, etc.), α-alkyl-substituted styrene (for example, α-methylstyrene, etc.) having an alkyl group substituted at the α-position. These aromatic vinyl monomers can be used alone or in combination of two or more. Of these monomers, styrene, vinyl toluene, α-methylstyrene and the like are usually used.

The aromatic vinyl monomer may be used in combination with a copolymerizable monomer (copolymerizable monomer). Examples of copolymerizable monomers include unsaturated polycarboxylic acids or acid anhydrides thereof (eg, maleic acid, itaconic acid, citraconic acid or acid anhydrides thereof), imide monomers [eg, maleimide N-alkylmaleimide (eg, N—C _1-4 alkylmaleimide), N-cycloalkylmaleimide (eg, N-cyclohexylmaleimide), N-arylmaleimide (eg, N-phenylmaleimide), etc. -Substituted maleimide], acrylic monomer [for example, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) (Meth) acrylic acid C _1-20 alkyl esters such as octyl acrylate, 2-ethylhexyl (meth) acrylate, (meth T) cyclohexyl acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, etc. (Meth) acrylic acid hydroxy C _2-4 alkyl ester etc.], vinyl cyanide monomer ((meth) acrylonitrile etc.) and the like.

  These copolymerizable monomers can be used alone or in combination of two or more. Among these copolymerizable monomers, acrylic monomers such as methyl (meth) acrylate, vinyl cyanide monomers such as (meth) acrylonitrile, particularly vinyl cyanide monomers such as acrylonitrile preferable. The amount of the copolymerizable monomer in all monomers can be selected from the range of usually 1 to 50% by weight, preferably 3 to 40% by weight, more preferably about 5 to 30% by weight.

  The weight average molecular weight of the styrene resin as the matrix resin is, for example, about 10,000 to 1,000,000, preferably about 50,000 to 500,000, and more preferably about 100,000 to 500,000.

Examples of the rubber-like polymer include diene rubber [polybutadiene (low cis type or high cis type polybutadiene), polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, butadiene-acrylonitrile copolymer, isobutylene. -Isoprene copolymer, styrene-isobutylene-butadiene copolymer rubber, etc.], ethylene-vinyl acetate copolymer, acrylic rubber (copolymer elastomer mainly composed of polyacrylic acid C _2-8 alkyl ester, etc.), ethylene -Α-olefin copolymer [ethylene-propylene rubber (EPR), etc.], ethylene-α-olefin-polyene copolymer [ethylene-propylene-diene rubber (EPDM), etc.], urethane rubber, silicone rubber, butyl rubber, water Diene rubber (hydrogenated styrene) Butadiene copolymer, and hydrogenated butadiene polymer) and the like. In these rubbery polymers, the copolymer may be a random or block copolymer, and the block copolymer has a structure of AB type, ABA type, tapered type, radial teleblock type. Copolymers and the like are included. These rubbery polymers can be used alone or in combination of two or more.

  A preferred rubber component is a polymer of conjugated 1,3-diene or a derivative thereof, particularly a diene rubber such as polybutadiene (butadiene rubber), isoprene rubber, styrene-butadiene copolymer.

  In the rubber-containing styrenic resin, the content of the rubber component is about 1 to 60% by weight, preferably about 3 to 30% by weight, and more preferably about 5 to 30% by weight (particularly 10 to 30% by weight). If the content of the rubber component is too small, the effect of improving the impact resistance is not sufficient, and if the content of the rubber component is too large, the rigidity decreases.

  The form of the rubber-like polymer dispersed in the matrix composed of the styrene resin is not particularly limited, and may be a salami structure, a core / shell structure, an onion structure, or the like.

  The particle diameter of the rubber-like polymer constituting the dispersed phase can be selected, for example, from the range of a weight average particle diameter of 230 to 3000 nm, preferably 240 to 2000 nm, more preferably about 240 to 1500 nm. The graft ratio of the rubbery polymer is about 5 to 150%, preferably about 10 to 150%.

  Examples of rubber-containing styrene resins include impact-resistant polystyrene (HIPS), methyl methacrylate-modified HIPS (transparent HIPS), styrene-acrylonitrile-butadiene copolymer (ABS resin), and methyl methacrylate-modified ABS resin (transparent ABS). Resin), α-methylstyrene-modified ABS resin, imide-modified ABS resin, styrene-methyl methacrylate-butadiene copolymer (MBS resin), AXS resin, methyl methacrylate-modified AXS resin, and other rubber-containing styrene resins. . Here, the AXS resin refers to a resin obtained by graft polymerization of acrylonitrile A and styrene S to rubber component X (acrylic rubber, chlorinated polyethylene, ethylene-propylene rubber, ethylene-vinyl acetate copolymer, etc.). These include acrylonitrile-acrylic rubber-styrene resin (AAS resin), acrylonitrile-ethylene-propylene rubber-styrene resin (AES resin), and the like. These rubber-containing styrenic resins can be used alone or in combination of two or more. Among these, the rubber-containing styrene resin is a rubber-grafted styrene resin containing an acrylic monomer and / or a vinyl cyanide monomer as a structural unit (the acrylic monomer and / or cyanide is included in the rubber component). For example, ABS resin, AAS resin, AES resin, MBS resin, methacrylic acid-modified AAS resin, and the like.

  In the present invention, the ratio of sodium, chlorine and sulfate ions contained in the rubber-containing styrenic resin (B) is, for example, 10 ppm (μg / g) or less in total, preferably 5 ppm or less, more preferably 1 ppm or less (particularly 0). 0.5 ppm or less).

  Such sodium, chlorine and sulfate ions are mixed in, for example, the production process of rubber-containing styrenic resin. However, if such elements and ions are present, the weldability of the resin member is lowered, which may cause gas generation. Become. The content of these elements and ions may be reduced by purifying the rubber-containing styrene resin, but may be reduced by adjusting or selecting the production method. For example, when producing a rubber-containing styrene resin by emulsion polymerization, suspension polymerization, or solution polymerization (particularly emulsion polymerization), a solvent used for polymerization, a surfactant, a polymerization initiator, a salt used for salting out, etc. It is preferable to use a rubber-containing styrenic resin produced by bulk polymerization because elements and ions derived from the above are mixed.

  The ratio (weight ratio) between the polyester resin (A) and the rubber-containing styrene resin (B) is the former / the latter = 90/10 to 10/90, preferably 90/10 to 20/80, more preferably 85. / 15 to 30/70 (80/20 to 40/60).

  The resin composition for laser welding of the present invention may contain other thermoplastic resins as long as the characteristics of both resins are not impaired. Examples of other thermoplastic resins include olefin resins, acrylic resins, vinyl resins, polycarbonate resins, polyamide resins, polyphenylene oxide resins, polyurethane resins, and the like. These other thermoplastic resins can be used alone or in combination of two or more. From the point of compatibility, polystyrene (GPPS), styrene-acrylonitrile copolymer (AS resin), styrene-methyl methacrylate copolymer (MS resin), acrylonitrile-styrene-methyl methacrylate copolymer, styrene-anhydrous malein Non-rubber-containing styrene resins such as acid copolymers (SMA resins), acrylic resins, and thermoplastic elastomers (such as styrene thermoplastic elastomers and polyester thermoplastic elastomers) are preferred.

  The resin composition of the present invention includes conventional additives such as compatibilizers, plasticizers, flame retardants, colorants, fillers (glass fibers, carbon fibers, metals) as long as the laser transmittance and resin properties are not deteriorated. Fillers, etc.), stabilizers (antioxidants, light stabilizers, heat stabilizers, etc.), lubricants, dispersants, foaming agents, antibacterial agents and the like may be included. These additives can be used alone or in combination of two or more.

  Among these additives, in particular, a filler may be used to suppress sink marks and improve heat resistance and mechanical properties. As the filler, a conventional inorganic or organic filler can be used, but from the viewpoint of laser transmission, a fibrous inorganic filler (for example, glass fiber, silica fiber, carbon fiber, alumina fiber, metal fiber, etc.), particularly Glass fiber can be preferably used. The average diameter of the glass fiber is, for example, about 1 to 50 μm (preferably 3 to 30 μm), and the average length may be, for example, about 100 μm to 3 mm (preferably 500 μm to 1 mm). A filler can be used individually or in combination of 2 or more types.

  The proportion of the filler can be selected from a range of about 0 to 100 parts by weight with respect to a total of 100 parts by weight of the polyester resin (A) and the rubber-containing styrene resin (B). Preferably it is 20-80 weight part, More preferably, it is about 30-80 weight part.

  Further, in order to improve the appearance characteristics of the molded product, a colorant may be used in particular. The colorant includes a colorant that can transmit laser light and a colorant that is non-absorbable with respect to laser light. Examples of such colorants include various chromatic or achromatic colorants, such as white dyes and pigments (for example, inorganic pigments such as titanium white, calcium carbonate, zinc oxide, zinc sulfide, and lithopone), yellow dyes [for example, , Inorganic pigments such as cadmium yellow (cadmium yellow), yellow lead (chrome yellow), zinc chromate, ocher (ocher), organic pigments such as hansa yellow, benzidine yellow, and pigment yellow], orange dye pigments, red dye pigments [for example , Red pigment, amber, cadmium red (fire red), inorganic pigments such as red lead (lead tetroxide, Komyotan), organic pigments such as permanent red, lake red, watch chan red, brilliant carmine 6B], Blue dyes [for example, inorganic pigments such as bitumen, ultramarine blue, cobalt blue (tenal blue), phthalocyanine blue, etc. Machine pigments, green dyes and pigments [e.g., inorganic pigments such as chrome green, organic pigments such as phthalocyanine green] and the like.

  As the colorant, the dyes and pigments exemplified above may be used alone, or a plurality of colorants may be used in combination to adjust to a desired color tone. For example, the resin can be colored black using three primary colors.

  The colorant may have a light scattering property. When such a colorant (for example, a pigment such as titanium oxide) is used, a light scattering property can be imparted to the molded product, and the bonded object can be effectively formed. It can also be concealed. When using a colorant that does not transmit laser light but reflects and diffuses it, the laser light is transmitted to the extent that laser welding is possible. It is preferable to do this.

  The ratio of the colorant is not particularly limited, but can be appropriately selected according to the type of the resin and the colorant, the oscillation wavelength of the laser beam, the color of the joined body, and the like. For example, the polyester resin (A) and the rubber-containing styrene system 0 to 10 parts by weight (for example, 0.0001 to 10 parts by weight), preferably 0.001 to 7 parts by weight, more preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the resin (B). It may be a degree.

  In the laser welding resin composition of the present invention, the ratio of the organic acid in the resin composition is, for example, about 2000 ppm (μg / g) or less, preferably 1000 ppm or less, more preferably 500 ppm or less (particularly 100 ppm or less). . Organic acids include carboxylic acids such as acetic acid, higher fatty acids such as lauric acid, organic sulfonic acids such as alkylbenzene sulfonic acid, and terpenic acids such as rosin acid.

  The organic acid is also mixed in, for example, the production process of the rubber-containing styrenic resin. However, the presence of the organic acid causes direct gas generation and decreases the weldability of the resin member. The content of the organic acid may be reduced by purifying the resin composition or the raw material resin, but may be reduced by adjusting the method for producing the raw material resin. For example, when producing a rubber-containing styrenic resin by emulsion polymerization, the organic acid derived from the solvent, surfactant, etc. used for the polymerization is mixed, and therefore the rubber-containing styrenic resin produced by bulk polymerization is used. preferable.

[Resin molding]
The resin molded body of the present invention is composed of the resin composition for laser welding, and may be used as a member that transmits laser light (transmitting member), or as a member that absorbs laser (absorbing member). May be used. Since the resin molding of the present invention is excellent in laser transmittance, it is usually used as at least a transmitting member.

  The transmittance of the resin molded body with respect to the laser beam is usually 10 in the thickness direction of the molded body having a thickness of 2 mm, for example, depending on the oscillation wavelength of the laser beam to be used (for example, a wavelength selected from the range of 740 to 1600 nm). % Or more (for example, about 10 to 100%), for example, 15 to 100%, preferably 20 to 100%, more preferably about 30 to 100% (particularly 40 to 100%).

  Such a resin molded body includes a polyester-based resin (A), a rubber-containing styrene-based resin (B), and other components (fillers, colorants, other thermoplastic resins, etc.) as necessary, as an extruder. Obtained by mixing (for example, melt-kneading) using a conventional mixing method using a kneader, mixer, roll, or the like, and molding by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, or the like. be able to.

  The shape of the resin molded body is not particularly limited as long as it has at least part of a contact surface (such as a flat surface) sufficient for bonding, and may be a two-dimensional shape (for example, a plate shape) or a three-dimensional shape. Good.

  The thickness of the resin molded body (at least the thickness of the laser welding position of the transmitting member) is, for example, 50 μm to 10 mm, preferably 70 μm to 8 mm, more preferably 100 μm, depending on the application and the laser light transmission or absorption. It may be about ˜5 mm.

[Composite molded body]
In the composite molded body of the present invention, the first molded body (joined body) composed of the resin composition and the second molded body (joined body) composed of a thermoplastic resin are joined by laser welding. Has been. As described above, since the joined body composed of the resin composition is excellent in laser transmittance, it is usually used as a transmissive member, and a joined body composed of a thermoplastic resin is used as an absorbing member. .

  The thermoplastic resin in the joined body is not particularly limited as long as it can be joined (or attached) to the joined body by laser welding, and various thermoplastic resins can be used.

Examples of the thermoplastic resin include polyamide resins (polyamide 5, polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, polyamide 612, polyamide 6/66, polyamide 6/11, and other aliphatic polyamide resins; Aromatic polyamide resins such as polyamide 6T, polyamide 9T, polyamide MXD; alicyclic polyamide resins, etc., polyester resins (poly C _2-4 alkylene terephthalate, poly C _2-4 alkylene naphthalate, copolyesters thereof) , Polyarylate, liquid crystalline polyester, etc.), polycarbonate resin (bisphenol A polycarbonate such as bisphenol A polycarbonate, hydrogenated bisphenol polycarbonate, etc.), olefin resin [polyethylene (low Polyethylene, high-density polyethylene, etc.), polypropylene, ethylene-propylene copolymers, olefin homo- or copolymers (including elastomers) such as ethylene-propylene rubber, etc.], styrene resins [polystyrene (GPPS, etc.), styrene -Acrylic copolymer (styrene- (meth) acrylic acid copolymer, AS resin, MS resin, etc.), styrene-diene or olefin copolymer (styrene-butadiene-styrene (SBS) block copolymer, styrene -Isoprene-styrene (SIS) block copolymer, etc.), rubber-containing styrene resin (HIPS, ABS resin, AXS resin (ASA resin, AES resin, etc.), MBS resin etc.), etc.], acrylic resin (eg, poly Poly (meth) a such as methyl methacrylate Alkyl acrylate, etc.), vinyl resins (vinyl chloride resins, vinyl acetate resins, ethylene-vinyl acetate copolymers, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, etc.), polyphenylene oxide resins [polyphenylene oxide, Modified polyphenylene oxide (blend with polystyrene, polyphenylene oxide grafted with polystyrene, etc.) and the like. These resins can be used alone or in combination of two or more. The thermoplastic resin constituting the resin molded body may be a crystalline resin or an amorphous resin.

  Among the thermoplastic resins, polyamide resins, polyester resins, polycarbonate resins, olefin resins, styrene resins, acrylic resins, vinyl resins, and polyphenylene oxide resins [particularly polyamide resins (such as polyamide 6) Aliphatic polyamide resins, etc.), olefin resins (polypropylene, ethylene-propylene copolymers and other olefin homo- or copolymers), styrene resins (rubber-containing styrene resins such as ABS resins), etc.] Is preferred. Furthermore, from the point of affinity with the joined body, a polyester resin, a styrene resin, or a combination thereof, particularly the laser welding resin composition is preferable.

  The joined body may contain a laser light absorbent and / or a colorant. In particular, when the member to be joined is used as an absorbing member and is laser transmissive (for example, when the resin composition for laser welding of the present invention is used), a thermoplastic resin, a laser light absorber and / or a colorant. And a laser absorbing ability may be imparted in combination.

  As the laser light absorber, for example, black pigments such as carbon black (for example, acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, etc.), titanium black, and black iron oxide may be used. Many. These laser light absorbers can be used alone or in combination of two or more. Moreover, these laser light absorbers may be added as a colorant. The average particle diameter of the black pigment can be selected from a wide range of about 10 nm to 3 μm (preferably 10 nm to 1 μm), for example. The average particle diameter of carbon black may be, for example, about 10 to 100 nm, preferably about 15 to 90 nm. The ratio of the laser light absorber is 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin constituting the joined body. It may be about parts by weight.

  Examples of the colorant include various inorganic or organic dyes and pigments used for coloring of resins, such as white dyes (such as titanium white), yellow dyes (such as benzidine yellow), and orange dyes (such as Hansa Yellow). ), Red dye pigment (organic pigment such as lake red), blue dye pigment (organic pigment such as phthalocyanine blue), green dye pigment (organic pigment such as phthalocyanine green), and the like. The ratio of the colorant is not particularly limited, and is, for example, 0 to 10 parts by weight (for example, 0.001 to 10 parts by weight), preferably about 0.01 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin. It may be.

  The joined body may contain the same conventional additive as the laser welding resin composition, if necessary.

  The composite molded body is formed by bringing a joined body (for example, a transmissive member) and a body to be joined (for example, an absorbing member) into surface contact with at least a joint portion between them and irradiating a laser beam. It is obtained by partially melting the interface with the body to bring the bonding surface into close contact, and cooling to bond (or integrate).

  As a laser light source used for welding, a laser light source having an oscillation wavelength of about 193 to 1600 nm can be used. In many cases, a laser (630 to 1550 nm), a titanium sapphire laser (Nd: YAG excitation, 690 to 1000 nm), or the like is used.

  The laser welding resin composition, molded product and composite molded product of the present invention are used for home or office automation (OA) equipment such as computers, word processors, printers, copiers, fax machines, telephones, mobile devices (cell phones, Components such as personal digital assistants (PDAs) and household appliances (TVs, VCRs, DVD (Digital Versatile Disc) players, air conditioners, refrigerators, washing machines, etc.) (housings, cases, covers, doors) In addition to cartridges (ink cartridges, toner cartridges, etc.), it is useful in applications such as automobile parts, household goods, and building materials.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the content of the symbol of each component used by the Example and the comparative example, and the evaluation method of each evaluation item are as follows.

[Each component of resin molding]
PBT: Polybutylene terephthalate (Wintech Polymer Co., Ltd., trade name “700FP”)
PET: Polyethylene terephthalate (Mitsubishi Rayon Co., Ltd., trade name “MA-521H”)
ABS1: ABS resin, polymer obtained by bulk polymerization method, rubber type: polybutadiene, rubber content 20% by weight, copolymerization ratio of monomer components constituting the matrix: styrene / acrylonitrile = 77/23 (weight ratio), rubber Weight average particle size 1300nm
ABS2: polymer obtained by emulsion polymerization method, rubber type: polybutadiene and styrene-butadiene copolymer (the former / the latter = 80/20 (weight ratio)), rubber content 27% by weight, monomer component constituting the matrix Copolymerization ratio: Styrene / acrylonitrile = 74/26 (weight ratio), rubber weight average particle diameter 350 nm
AS: AS resin, copolymerization ratio of monomer components constituting the matrix: styrene / acrylonitrile = 73/27 (weight ratio), solution viscosity ηsp / c (4 mg / ml chloroform solution, 25 ° C.): 0.85
GF: Glass fiber (manufactured by Nippon Electric Glass Co., Ltd., trade name “CS-03-T-120”), average diameter 13 μm, average length 3 mm.

[Transmittance of laser light]
Place a set of 60φ integration balls for ultraviolet-visible-near infrared region in a spectrophotometer (manufactured by Hitachi, Ltd., U-3410), set a test piece, and measure transmittance at wavelength λ = 840 nm. The evaluation was based on the following criteria.

○: 30% or more Δ: 20% or more and less than 30% ×: less than 20%

[Organic acid concentration]
A sample of 20 mg was precisely weighed and heated at 250 ° C. for 10 minutes to trap the gas generated by a −50 ° C. collection tube, and then regasified at a Curie point. The regasified sample was injected into a gas chromatography analyzer [analytical instrument: Hewlett Packard, HP5890II type, detector: hydrogen flame ionization detector (FID)]. The total amount of organic acid was measured (unit: ppm (μg / g)).

(Measurement condition)
Oven: 100 ° C, 5 minutes
100-240 ° C (temperature rise at 10 ° C / min)
Detector: 300 ° C.

[Sodium concentration]
Sample 2g was precisely weighed in a platinum crucible and carbonized with an electric heater and a burner, and then ashing was completed in an electric furnace (400 ° C, 1.5 hours and 500 ° C, 2 hours). A small amount of ultrapure water and 0.5 ml of nitric acid were added to this ashed product and heated on a sand bath to dissolve the ash. After evaporation to dryness, a 0.1N nitric acid aqueous solution was added, and the volume was increased to 20 ml to obtain a test solution for atomic absorption analysis. The total amount of sodium in this test solution was measured (unit: ppm (μg / g)) using an atomic absorption analyzer (manufactured by Shimadzu Corporation, AA-680).

  In addition, the blank test using the crucible which is not filled with a sample was done, and this blank value was subtracted and it was set as the total amount of sodium in a sample. For the calibration curve standard solution, a commercially available standard solution for atomic absorption analysis was appropriately diluted with a 0.1N nitric acid aqueous solution, and a sodium concentration of 0, 0.02, 0.05, 0.1, 0.5, 1.0 μg was used. The one adjusted to / ml was used.

[Chlorine concentration]
20-30 mg of a sample was precisely weighed, and the total amount of chlorine in the sample was measured by a coulometric titration method using a chlorine analyzer (manufactured by Mitsubishi Chemical Co., Ltd., TOX-100) (unit: ppm (μg / g)). ).

[Sulfate ion concentration]
6 g of a sample was precisely weighed and filled in a polytetrafluoroethylene (Teflon: registered trademark) container that had been washed with ultrapure water in advance. And extracted with steam. This solution was diluted as appropriate and measured with the following anion analyzer using the filtrate filtered through a 0.2 μm membrane filter as the measurement solution (unit: ppm (μg / g)).

Equipment used: DIONEX DX-320
Precolumn: AG-15
Column: AS-15
Eluent: 5-70 mM KOH gradient Flow rate: 0.5 ml / min Detector: Electrical conductivity detector Column temperature: 30 ° C
Injection volume: 200 μl.

[warp]
A flat plate molded into a size of 120 mm in length × 120 mm in width × 2 mm in thickness is placed on a flat horizontal plane so that the center of the flat plate is in contact with the horizontal plane (if there is warping, each corner will float up) ) Next, after fixing each corner part to a horizontal plane, the height (lifting height) of the corner part on the diagonal with respect to the fixed corner part was measured. This was measured for each corner, and the largest lifting height was evaluated according to the following criteria.

○: Less than 2 mm Δ: 2 mm or more and less than 10 mm ×: 10 mm or more.

[Weldability]
After laser welding, using a tensile tester (Orientec Corp., Tensilon UCT-1T), each of the absorbing member and the transmissive member is bonded to the bonding part under the conditions of a distance between chucks of 80 mm and a head speed of 5.0 mm / min. The center was pulled outwardly, and the broken state was visually observed and evaluated according to the following criteria.

○: High weld strength and fracture at a portion other than the weld surface Δ: Slightly low weld strength, fracture at the weld surface and portions other than the weld surface ×: Low weld strength and fracture at the weld surface

[Amount of generated gas]
The amount of gas generated during laser welding was visually evaluated according to the following criteria.

○: Less △: Slightly more ×: More

[Heating deformation temperature (HDT)]
It was measured at a load of 1.8 MPa according to ISO 75.

[Shock resistance]
Using the obtained molded article, a test piece was prepared in accordance with ISO 179 / 1eA. Both ends of the test piece were supported and subjected to a Charpy impact tester to measure the impact strength (kJ / m ² ).

Examples 1-5 and Comparative Examples 1-4
Using the resin composition having the composition shown in Table 1, a resin molded body (three-stage plate, length 90 mm × width 50 mm × thickness 1, 2 and 3 mm) (laser light transmitting member) is molded, and the composition shown in Table 1 A laser light absorbing member having the same size and shape as the molded body was molded using a resin composition containing 0.5% by weight of carbon black based on the total composition.

  A laser beam transmitting member is placed on the black colored laser beam absorbing member, and a transparent glass plate is placed on the transmitting member as a weight. ) Were used to weld (welding conditions: output 40 W and scanning speed 10 mm / second). The absorption-side three-stage plate and the transmission-side three-stage plate were overlapped, and the laser beam was irradiated to a position where both the transmission member and the absorption member had a thickness of 2 mm. Table 1 shows the results of evaluating the characteristics of the obtained composite molded body.

  As is apparent from the table, in the examples, a composite molded body having no warp and having high weldability, heat resistance, and impact resistance is produced without generating gas. On the other hand, Comparative Examples 1 and 3 do not contain ABS resin, and therefore have low weldability, impact resistance, warpage, and the like. In Comparative Examples 2 and 4, since AS resin is used, impact resistance cannot be improved.

Claims (10)

A resin composition for forming a molded body that can be bonded to a resin molded body by laser light irradiation, the polyester resin (A) and a styrene resin containing 10 to 30 % by weight of a rubber component (B), the ratio (weight ratio) of the polyester resin (A) and the styrene resin (B) is the former / the latter = 80/20 to 40/60, and in the composition The resin composition for laser welding in which the ratio of the organic acid contained in is 2000 ppm or less.   The resin composition according to claim 1, wherein the ratio of sodium, chlorine and sulfate ions contained in the styrene-based resin (B) is 10 ppm or less in total.   The resin composition according to claim 1, wherein the ratio of the organic acid contained in the composition is 1000 ppm or less.   The resin composition according to claim 1, wherein the styrene resin (B) is a rubber-grafted styrene resin containing at least one selected from an acrylic monomer and a vinyl cyanide monomer as a constituent unit. The resin composition according to claim 1, wherein the polyester resin (A) is a polyester resin containing at least a C _2-4 alkylene arylate unit.   The polyester resin (A) is composed of a polyester resin containing at least a butylene terephthalate unit, and the styrene resin (B) is acrylonitrile-butadiene rubber-styrene resin, acrylonitrile-acrylic rubber-styrene resin, acrylonitrile-ethylene The resin composition according to claim 1, wherein the resin composition is at least one selected from propylene rubber-styrene resin, methyl methacrylate-butadiene rubber-styrene resin, and methyl methacrylate-acrylonitrile-butadiene rubber-styrene resin.   The molded object comprised with the resin composition of Claim 1.   A composite molded body in which a first molded body composed of the resin composition according to claim 1 and a second molded body composed of a thermoplastic resin are joined by laser welding. The composite molded body according to claim 8 , wherein the first molded body is a member that transmits laser light.   The method to join the 1st molded object comprised with the resin composition of Claim 1 and the 2nd molded object comprised with the thermoplastic resin by irradiating a laser beam.