JP7242245B2 - Manufacturing method of laser welded body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a laser-welded body, and more particularly to a method for manufacturing a laser-welded body in which a member made of a polyester resin is laser-welded with stable high welding strength.

BACKGROUND ART In recent years, automobile parts and consumer parts are becoming lighter and more environmentally friendly, such as recycling. Polyester resin has excellent mechanical strength, chemical resistance, electrical insulation, etc., and also has excellent heat resistance, moldability, and recyclability, so it is widely used for various equipment parts. . In particular, thermoplastic polyester resins such as polybutylene terephthalate resin are excellent in mechanical strength and moldability, and can be made flame-retardant, so they are widely used in electrical and electronic equipment parts that require fire safety. ing.

Spaces are provided inside these equipment parts to accommodate electronic circuits, driving parts such as motors and fans, electronic circuits, connectors, etc. Molded products for these are divided into multiple resin members. By joining the molded parts together, compared with the case of integral molding, it is possible to optimize the shape by reducing the weight and making it hollow.
Methods for joining resin members include methods using adhesives, mechanical joining, hot plate welding, vibration welding, ultrasonic welding, and heat welding. A method for manufacturing a laser welded body has been attracting attention because of its advantages such as less influence on the body and good workability.

In laser welding, the parts to be joined of a transmission side member that transmits laser light and an absorption side member that absorbs laser light are overlapped, and laser light is irradiated from the transmission side member side to the joining surface to scan. The absorption side member is melted to weld the two members together.
However, thermoplastic polyester resins, particularly polybutylene terephthalate resins, have low laser transmittance compared to polycarbonate resins, polystyrene resins, and the like, and thus have poor laser weldability and tend to have insufficient welding strength.

In addition, since polybutylene terephthalate resin is a crystalline resin, a member molded from the polybutylene terephthalate resin is likely to have a difference in height due to warpage deformation, and a gap is generated between the joint surfaces of the resin members to be joined. In such cases, it becomes more difficult to obtain high weld strength.

In order to improve the laser weldability of polybutylene terephthalate resin, a method of compounding polybutylene naphthalate (PBN) or polyethylene naphthalate (PEN) has been proposed (Patent Document 1). However, this technique is not sufficient to improve the weld strength of members with gaps at the joining surfaces.

In Patent Document 2, in order to improve the welding strength of a member having a gap on the joint surface, it is proposed to install a convex part in the part to be welded, but the width of the part to be welded for installing the convex part is proposed. This is not necessarily desirable because it limits the size and shape and limits the welding conditions.

Japanese Patent No. 3510817 Japanese Patent Application Laid-Open No. 2011-5705

In view of the above situation, the object (problem) of the present invention is to obtain a stable and high welding strength with a low pressure without providing a convex portion even in a polyester member having a gap on the joint surface. To provide a laser welding method capable of

As a result of repeated studies to solve the above problems, the present inventors used a transmission side member that transmits at least a part of the laser light and an absorption side member that absorbs the laser light, and the transmission side member is a thermoplastic polyester The absorption side member is made of a composition containing a coloring material capable of transmitting and absorbing laser light with respect to resin (hereinafter referred to as "laser light transmitting and absorbing coloring material"), and the absorption side member is a thermoplastic polyester resin 100 parts by mass. A composition containing 0.001 to 0.15 parts by mass of a coloring material capable of absorbing laser light without transmitting it (hereinafter referred to as "laser light absorbing coloring material"), which is less than usual, The above problem can be solved by not having a convex structure at the junction with the side member and by providing a recess with a depth of 0.1 μm or more in the junction surface of the transmission-side member or the absorption-side member. I found it and arrived at the present invention.
The present invention relates to a method for manufacturing a laser-welded body and a kit for manufacturing a laser-welded body as described below.

[1] A method for manufacturing a laser-welded body in which at least a part of a transmission-side member that transmits laser light and an absorption-side member that absorbs laser light are laser-welded via a joint surface,
The transmitting side member is made of a composition containing a laser light transmitting and absorbing coloring material for a thermoplastic polyester resin, and the absorbing side member contains 0.00% laser light absorbing coloring material for 100 parts by mass of the thermoplastic polyester resin. 001 to 0.15 parts by mass of a composition containing
The joint surface between the transmission-side member and the absorption-side member does not have a convex structure, and the joint surface of the transmission-side member and/or the absorption-side member has a concave portion with a depth of 0.1 μm or more. A method for manufacturing a laser welded body characterized by:
[2] The method for producing a laser-welded body according to [1] above, wherein the laser light transmitting and absorbing coloring material is nigrosine and the laser light absorbing coloring material is carbon black.
[3] A kit for manufacturing a laser-welded body including at least a part of a transmission side member that transmits laser light and an absorption side member that absorbs laser light,
The transmitting side member is made of a composition containing a laser light transmitting and absorbing coloring material in a thermoplastic polyester resin, and the absorption side member contains 0.001 to 0.001 to 0 of the laser light absorbing coloring material with respect to 100 parts by mass of the thermoplastic polyester resin. .15 parts by mass of a composition containing
Laser welding characterized in that each bonding surface of both members does not have a convex structure, and a concave portion having a depth of 0.1 μm or more is provided on the bonding surface of the transmission-side member and/or the absorption-side member. Body building kit.
[4] The kit for producing a laser-welded body according to [3] above, wherein the laser light transmitting and absorbing coloring material is nigrosine and the laser light absorbing coloring material is carbon black.

According to the method for producing a laser-welded body of the present invention, even a polyester member having gaps between the joining surfaces can be laser-welded with stable high welding strength.

1 is an overview diagram of a method for manufacturing a laser-welded body showing an embodiment of the present invention; FIG. FIG. 4 is a perspective view showing the shape of the joint surface of the absorption-side member used in Examples and Comparative Examples. It is the figure which showed the permeation|transmission side member I for airtightness measurement produced in the Example.

The method for producing a laser-welded body of the present invention is a method for producing a laser-welded body in which at least a part of a transmission side member that transmits laser light and an absorption side member that absorbs laser light are laser-welded via a joint surface. hand,
The transmitting side member is made of a composition containing a laser light transmitting and absorbing coloring material for a thermoplastic polyester resin, and the absorbing side member contains 0.00% laser light absorbing coloring material for 100 parts by mass of the thermoplastic polyester resin. 001 to 0.15 parts by mass of a composition containing
The joint surface between the transmission-side member and the absorption-side member does not have a convex structure, and the joint surface of the transmission-side member and/or the absorption-side member has a concave portion with a depth of 0.1 μm or more. characterized by

The contents of the present invention will be described in detail below. Although the following description may be made based on representative embodiments and specific examples of the present invention, the present invention should not be construed as being limited to such embodiments and specific examples.

[Thermoplastic polyester resin (A)]
The transmission-side member and the absorption-side member used in the method for producing a laser-welded body of the present invention consist of molded articles of thermoplastic polyester resin (A).

The thermoplastic polyester resin (A) includes (A1) polybutylene terephthalate homopolymer, (A2) polybutylene terephthalate copolymer resin, (A3) homo PBT mixed resin containing polybutylene terephthalate homopolymer, or (A4 ) a copolymerized PBT-based mixed resin containing a polybutylene terephthalate copolymerized resin.

<(A1) Polybutylene terephthalate homopolymer>
Polybutylene terephthalate homopolymer (also referred to as "homo PBT") is a polymer having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded. It is a polymer.

The amount of terminal carboxyl groups of homo-PBT is preferably 60 eq/ton or less, more preferably 50 eq/ton or less, and even more preferably 30 eq/ton or less.
The terminal carboxyl group content of polybutylene terephthalate homopolymer can be obtained by dissolving 0.5 g of resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol/l benzyl alcohol solution of sodium hydroxide. can.
As a method for adjusting the amount of terminal carboxyl groups, any conventionally known method may be used, such as a method of adjusting polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and a decompression method, or a method of reacting a terminal blocking agent. You can do it.

Homo PBT preferably has an intrinsic viscosity of 0.5 to 2.0 dl/g. If the intrinsic viscosity is 0.5 dl/g or more, the mechanical strength of the weld body does not become too low. It is possible to prevent deterioration of laser weldability.
From this point of view, the intrinsic viscosity of the homo-PBT is preferably 0.5 to 2 dl/g, especially 0.6 dl/g or more, or 1.5 dl/g or less, especially 0.7 dl/g or more, or It is more preferably 1.2 dl/g or less.
The intrinsic viscosity is a value measured at 30° C. in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

<(A2) Polybutylene terephthalate copolymer resin>
Polybutylene terephthalate copolymer resin (also referred to as “copolymerized PBT”) is a polybutylene terephthalate copolymer containing other copolymer components other than terephthalic acid units and 1,4-butanediol units.

Examples of dicarboxylic acid units other than terephthalic acid include isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2′- Aromas such as dicarboxylic acids, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid dicarboxylic acids, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4′-dicyclohexyldicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and dimer acid, etc. can be mentioned.

Diol units other than 1,4-butanediol include aliphatic or alicyclic diols having 2 to 20 carbon atoms and bisphenol derivatives. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, and 4,4′-dicyclohexylhydroxymethane. , 4,4′-dicyclohexylhydroxypropane, ethylene oxide-added diol of bisphenol A, and the like.

From the viewpoint of mechanical properties and heat resistance, the copolymerized PBT preferably has a ratio of terephthalic acid in dicarboxylic acid units of 70 mol % or more, more preferably 90 mol % or more.
Also, the proportion of 1,4-butanediol in the diol units is preferably 70 mol % or more, more preferably 90 mol % or more.

In addition to the bifunctional monomers described above, the copolymerized PBT may contain trifunctional or tetrafunctional alcohols such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane to introduce a branched structure. A small amount of a polyfunctional monomer or a monofunctional compound such as a fatty acid may be used in combination for adjusting the molecular weight.

Copolymerized PBT particularly includes polybutylene terephthalate resin obtained by copolymerizing polyalkylene glycols (especially polytetramethylene glycol (PTMG)), dimer acid-copolymerized polybutylene terephthalate resin, and especially isophthalic acid as a copolymerization component. A copolymer polybutylene terephthalate resin is preferred.

In the copolymerized PBT obtained by copolymerizing polytetramethylene glycol (PTMG), the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass. Among them, the content is more preferably 10% by mass or more or 25% by mass or less. Such a copolymerization ratio tends to provide an excellent balance between laser weldability and heat resistance, which is preferable.
On the other hand, in the case of a copolymerized PBT obtained by copolymerizing a dimer acid, the ratio of the dimer acid component to the total carboxylic acid component is preferably 0.5 to 30 mol% as a carboxylic acid group, especially 1 mol% or more. Alternatively, it is 20 mol % or less, more preferably 3 mol % or more or 15 mol % or less. Such a copolymerization ratio tends to provide an excellent balance between laser weldability, long-term heat resistance, and toughness, which is preferable.
In the case of a copolymerized PBT obtained by copolymerizing isophthalic acid, the proportion of the isophthalic acid component in the total carboxylic acid component is preferably 1 to 30 mol % as carboxylic acid groups, especially 2 mol % or more, or 20 mol % or less, more preferably 3 mol % or more or 15 mol % or less. Such a copolymerization ratio tends to provide an excellent balance of laser weldability, heat resistance, injection moldability and toughness, which is preferable.
As the copolymerized PBT, from the viewpoint of laser weldability and moldability, a copolymerized PBT obtained by copolymerizing polytetramethylene glycol or a copolymerized PBT obtained by copolymerizing isophthalic acid is particularly preferable.

Copolymerized PBT preferably has an intrinsic viscosity of 0.5 to 2.0 dl/g. If the intrinsic viscosity is 0.5 dl/g or more, the mechanical strength of the weld body does not become too low. It is possible to prevent deterioration of laser weldability.
From this point of view, the intrinsic viscosity of the copolymerized PBT is preferably 0.5 to 2.0 dl/g, especially 0.6 dl/g or more or 1.5 dl/g or less, especially 0.7 dl/g or more. Alternatively, it is more preferably 1.2 dl/g or less.
The intrinsic viscosity is a value measured at 30° C. in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

The terminal carboxyl group content of the copolymerized PBT is preferably 60 eq/ton or less. When the amount of terminal carboxyl groups is 60 eq/ton or less, generation of gas can be suppressed during melt molding of the resin composition.
From this point of view, the terminal carboxyl group content of the copolymerized PBT is preferably 60 eq/ton or less, more preferably 50 eq/ton or less, and more preferably 30 eq/ton or less.
On the other hand, the lower limit of the amount of terminal carboxyl groups is not particularly defined. It is usually 5 eq/ton or more.
The terminal carboxyl group content of copolymerized PBT can be obtained by dissolving 0.5 g of resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol/l benzyl alcohol solution of sodium hydroxide.
As a method for adjusting the amount of terminal carboxyl groups, any conventionally known method may be used, such as a method of adjusting polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and a decompression method, or a method of reacting a terminal blocking agent. You can do it.

<(A3) Homo-PBT mixed resin containing polybutylene terephthalate homopolymer>
Homo PBT mixed resin containing polybutylene terephthalate homopolymer (also referred to as "homo PBT mixed resin") is polybutylene terephthalate homopolymer (A3-1), polybutylene terephthalate copolymer resin, polyethylene terephthalate resin, polycarbonate resin. and at least one resin (A3-2) selected from the group consisting of aromatic vinyl resins.

(Polybutylene terephthalate homopolymer (A3-1))
The polybutylene terephthalate homopolymer is the same as the polybutylene terephthalate homopolymer (A1) described above.

(Polybutylene terephthalate copolymer resin (A3-2-1))
The polybutylene terephthalate copolymer resin (A3-2-1) is the same as the polybutylene terephthalate copolymer resin (A2) described above.

(Polyethylene terephthalate resin (A3-2-2))
The polyethylene terephthalate resin (also referred to as “PET”) is a resin containing oxyethyleneoxyterephthaloyl units composed of terephthalic acid and ethylene glycol as main structural units for all structural repeating units.
It may contain a repeating unit having a constitution other than the oxyethyleneoxyterephthaloyl unit.

PET is produced using terephthalic acid or its lower alkyl ester and ethylene glycol as main raw materials. Other acid components and/or other glycol components may be used together as raw materials.

Examples of acid components other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3 -Phenylenedioxydiacetic acid and structural isomers thereof, dicarboxylic acids such as malonic acid, succinic acid and adipic acid and derivatives thereof, oxyacids such as p-hydroxybenzoic acid and glycolic acid, and derivatives thereof. .
Diol components other than ethylene glycol include aliphatic glycols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol and neopentyl glycol, Alicyclic glycols such as cyclohexanedimethanol and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S can be used.

PET is a branched component, for example trifunctional acids such as tricarballylic acid, trimellitic acid, trimellitic acid, etc., or tetrafunctional acids such as pyromellitic acid, or acids with ester-type performance such as glycerin, trimethylolpropane, pentaerythritol, etc. preferably 1.0 mol % or less, more preferably 0.5 mol % or less, still more preferably 0.3 mol % or less of an alcohol having trifunctional or tetrafunctional ester-forming ability such as may

The intrinsic viscosity of PET is preferably 0.3 to 1.5 dl/g, especially 0.4 dl/g or more or 1.2 dl/g or less, especially 0.5 dl/g or more or 0.8 dl/g More preferably:
The intrinsic viscosity of polyethylene terephthalate resin is a value measured at 30° C. in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

The terminal carboxyl group content of PET is preferably 3 to 60 eq/ton. By setting the amount of terminal carboxyl groups to 60 eq/ton or less, gas is less likely to be generated during melt molding of the resin material, and the resulting laser welding member tends to have improved mechanical properties. is 3 eq/ton or more, the heat resistance, retention heat stability, and hue of the member for laser welding tend to be improved, which is preferable.

From this point of view, the amount of terminal carboxyl groups of PET is preferably 3 to 60 eq/ton, more preferably 5 eq/ton or more or 50 eq/ton or less, more preferably 8 eq/ton or more or 40 eq/ton or less. preferable.
The terminal carboxyl content of polyethylene terephthalate resin is obtained by dissolving 0.5 g of polyethylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol/L benzyl alcohol solution of sodium hydroxide. is.
As a method for adjusting the amount of terminal carboxyl groups, any conventionally known method may be used, such as a method of adjusting polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and a decompression method, or a method of reacting a terminal blocking agent. You can do it.

(Polycarbonate resin (A3-2-2))
The polycarbonate resin (also referred to as "PC") is an optionally branched thermoplastic polymer or copolymer obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonic acid diester. is.
The method for producing PC is not particularly limited, and one produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester exchange method) can be used. Polycarbonate resin is preferred from the viewpoint of laser light transmittance and laser weldability.

The dihydroxy compound used as a raw material is preferably an aromatic dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane (that is, bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, Hydroquinone, resorcinol, 4,4-dihydroxydiphenyl and the like, preferably bisphenol A. A compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound can also be used.

As PC, among those mentioned above, aromatic polycarbonate resins derived from 2,2-bis(4-hydroxyphenyl)propane, or 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds Aromatic polycarbonate copolymers derived from and are preferred. Further, it may be a copolymer such as a copolymer with a polymer or oligomer having a siloxane structure. Furthermore, two or more of the above polycarbonate resins may be mixed and used.

The viscosity-average molecular weight of PC is preferably 5,000 to 30,000. When a PC having a viscosity-average molecular weight of 5000 or more is used, the mechanical strength of the obtained weld body can be maintained. It is possible to suppress deterioration of laser weldability.
From this point of view, the viscosity average molecular weight of PC is preferably 5,000 to 30,000, more preferably 10,000 or more or 28,000 or less, and more preferably 14,000 or more or 24,000 or less.
The viscosity-average molecular weight of PC is the viscosity-average molecular weight [Mv] converted from the solution viscosity measured at 25° C. using methylene chloride as a solvent.

The ratio (Mw/Mn) of the weight average molecular weight Mw in terms of polystyrene and the number average molecular weight Mn measured by gel permeation chromatography (GPC) of PC is preferably 2 to 5, especially 2. More preferably, it is 5 or more or 4 or less. If Mw/Mn is too small, the fluidity in the molten state tends to increase and the moldability tends to decrease. On the other hand, if Mw/Mn is too large, the melt viscosity tends to increase, making molding difficult.

In addition, the amount of terminal hydroxyl groups of PC is preferably 100 mass ppm or more, more preferably 120 mass ppm or more, still more preferably 150 mass ppm or more, from the viewpoint of thermal stability, hydrolysis stability, color tone, etc. , and most preferably at least 200 mass ppm. However, it is usually 1500 mass ppm or less, preferably 1300 mass ppm or less, more preferably 1200 mass ppm or less, most preferably 1000 mass ppm or less. If the amount of terminal hydroxyl groups in the polycarbonate resin is too small, the laser transmittance tends to be lowered, and the initial color hue during molding may deteriorate. If the amount of terminal hydroxyl groups is excessively large, the retention heat stability and the resistance to moist heat tend to decrease.

(Aromatic vinyl resin (A3-2-3))
Aromatic vinyl resins are polymers containing aromatic vinyl compounds as main components. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, paramethylstyrene, vinyltoluene, and vinylxylene. can.
A copolymer obtained by copolymerizing an aromatic vinyl compound with another monomer can also be used as the aromatic vinyl resin. Typical examples include acrylonitrile-styrene copolymer (AS resin) obtained by copolymerizing styrene and acrylonitrile, maleic anhydride-styrene copolymer obtained by copolymerizing styrene and maleic anhydride (maleic anhydride-modified polystyrene resin) can be mentioned.
Representative examples of aromatic vinyl resins include polystyrene (PS), acrylonitrile-styrene (AS), methyl methacrylate-styrene (MS), and styrene-maleic acid copolymer.

A rubber component can be copolymerized with the aromatic vinyl resin. Examples of rubber components include conjugated diene hydrocarbons such as butadiene, isoprene, and 1,3-pentadiene. When the rubber component is copolymerized, the amount of the rubber component to be copolymerized should be 1% by mass or more and less than 50% by mass in all segments of the aromatic vinyl resin. The amount of rubber component is preferably 3-40% by weight, more preferably 5-30% by weight.

Rubber component copolymerized aromatic vinyl resins include, for example, rubber-modified polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylic rubber copolymer, methyl methacrylate-butadiene-styrene (MBS), and acrylonitrile. -Styrene-acrylic acid (ASA), styrene-butadiene copolymer (SBS) and hydrides thereof (SEBS), styrene-isoprene copolymers (SIS) and hydrides thereof (SEPS), etc. .

Other copolymerizable monomers include, for example, α,β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid; , β-unsaturated carboxylic acid esters, α,β-unsaturated dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride, α such as N-phenylmaleimide, N-methylmaleimide and Nt-butylmaleimide , and imide compounds of β-unsaturated dicarboxylic acids.

The aromatic vinyl resin preferably has a weight average molecular weight of 50,000 to 500,000 as measured by GPC. If the molecular weight is 50,000 or more, bleeding out can be suppressed, and a decrease in weld strength due to decomposition gas generation during molding can be suppressed. On the other hand, if the molecular weight is 500,000 or less, fluidity and laser welding strength can be enhanced. From this point of view, the aromatic vinyl resin preferably has a mass average molecular weight measured by GPC of 50,000 to 500,000, more preferably 100,000 or more or 400,000 or less, and more preferably 150,000 or more or 300,000 or less.

When the aromatic vinyl resin is an acrylonitrile-styrene copolymer, it preferably has a melt flow rate (MFR) of 0.1 to 50 g/10 minutes measured at 220° C. and 98 N. If the MFR is 0.1 g/10 minutes or more, the compatibility with the polybutylene terephthalate resin is good, and appearance defects such as delamination can be suppressed during injection molding. On the other hand, if the MFR is 50 g/10 minutes or less, the decrease in impact resistance can be suppressed. From this point of view, the melt flow rate (MFR) of the aromatic vinyl resin is preferably 0.1 to 50 g/10 minutes, especially 0.5 g/10 minutes or more or 30 g/10 minutes or less, especially It is more preferably 1 g/10 minutes or more or 20 g/10 minutes or less.

Further, when the aromatic vinyl resin is polystyrene, the MFR measured at 200° C. and 48 N is preferably 1 to 50 g/10 min, especially 3 g/10 min or more or 35 g/10 min or less. Among them, it is more preferably 5 g/10 minutes or more or 20 g/10 minutes or less.
When the aromatic vinyl resin is butadiene rubber-containing polystyrene, the MFR measured at 200° C. and 49 N is preferably 0.1 to 40 g/10 min, especially 0.5 g/10 min or more or 30 g/ 10 minutes or less, more preferably 0.8 g/10 minutes or more or 20 g/10 minutes or less.

(Homo PBT and copolymer PBT)
(A3) When the homo-PBT-based mixed resin contains homo-PBT and copolymerized PBT, the content of copolymerized PBT is 10 to 90% by weight in a total of 100% by weight of homo-PBT and copolymerized PBT. is preferred.
When the content of the copolymerized PBT is 10% by mass or more, the laser welding performance is improved, and when the content is 90% by mass or less, the moldability is improved, which is preferable. From this point of view, the content of the copolymerized PBT in the total 100% by mass of the homo PBT and the copolymerized PBT is preferably 10 to 90% by mass, especially 15% by mass or more or 85% by mass or less, and among them 20% by mass. % or more or 80 mass % or less.

(homo PBT + PET)
(A3) When the homo PBT-based mixed resin contains homo PBT and PET, the content of PET is preferably 5 to 50% by mass based on the total 100% by mass of homo PBT and PET. When the content of PET is 5% by mass or more, the laser welding performance is enhanced, and when the content is 50% by mass or less, moldability is improved, which is preferable. From this point of view, the content of PET in the total 100% by mass of homo PBT and PET is preferably 5 to 50% by mass, especially 10% by mass or more or 45% by mass or less, and among them 15% by mass or more or 40% by mass. % by mass or less is more preferable.

(homo PBT + PC)
(A3) When homo-PBT-based mixed resin contains homo-PBT and PC, the content of PC is preferably 5 to 50% by mass based on the total 100% by mass of homo-PBT and PC. When the content of PC is 5% by mass or more, the laser welding performance is improved, and when the content is 50% by mass or less, moldability is improved, which is preferable. From this point of view, the content of PC in the total 100% by mass of homo PBT and PC is preferably 5 to 50% by mass, especially 10% by mass or more or 45% by mass or less. % by mass or less is more preferable.

(Homo PBT + aromatic vinyl resin)
(A3) When the homo-PBT-based mixed resin contains homo-PBT and an aromatic vinyl-based resin, the content of the aromatic vinyl-based resin is 5% in the total 100% by mass of the homo-PBT and the aromatic vinyl-based resin. It is preferably ~50% by mass. When the content of the aromatic vinyl resin is 5% by mass or more, the laser welding performance is improved, and when the content is 50% by mass or less, the moldability is improved, which is preferable. From this point of view, the content of the aromatic vinyl resin in the total 100% by mass of the homo PBT and the aromatic vinyl resin is preferably 5 to 50% by mass, especially 10% by mass or more or 45% by mass or less, Among them, the content is more preferably 15% by mass or more or 40% by mass or less.

In the above description, preferred content ratios when homo PBT (A3-1) is combined with one of copolymerized PBT, PET, PC and aromatic vinyl resin (A3-2) are described. However, a plurality of types may be used by appropriately selecting from the above (A3-2). In addition, it is preferable that the total of (A3-2) does not exceed 100% by mass in each ratio range.
For example, as (A3-2), when an aromatic vinyl resin and PC are used in combination, a total of 50% by mass or more of homo PBT, 5 to 50% by mass of aromatic vinyl resin, and 5 to 50% by mass of PC is preferably 100% by mass.
Also in (A4) described later, when multiple types are used from (A4-2), they can be combined based on the same idea as above.

<(A4) Copolymerized PBT mixed resin containing polybutylene terephthalate copolymerized resin>
Copolymerized PBT-based mixed resin containing polybutylene terephthalate copolymerized resin (hereinafter also referred to as "copolymerized PBT-based mixed resin") consists of copolymerized PBT (A4-1), PET, PC and aromatic vinyl resin. A resin composition containing at least one resin (A4-2) selected from the group is preferable.

At this time, the copolymerized PBT (A4-1) in the copolymerized PBT-based mixed resin (A4) is the same as the copolymerized PBT in the homo-PBT-based mixed resin (A3).
The PET, PC and aromatic vinyl resin in the copolymerized PBT mixed resin (A4) are the same as the PET, PC and aromatic vinyl resin in the homo PBT mixed resin (A3).

(Copolymerized PBT + PET)
When the copolymerized PBT-based mixed resin (A4) contains copolymerized PBT and PET, the content of PET is preferably 50% by mass or less in a total of 100% by mass of copolymerized PBT and PET. If the content of PET is 50% by mass or less, it is preferable because moldability is excellent. From this point of view, the content of PET in the total 100% by mass of copolymerized PBT and PET is preferably 50% by mass or less, especially 5% by mass or more or 40% by mass or less, and among them 5% by mass or more or 30% by mass. % by mass or less is more preferable.

(Copolymerized PBT + PC)
When the copolymerized PBT-based mixed resin (A4) contains copolymerized PBT and PC, the content of PC is preferably 50% by mass or less in a total of 100% by mass of copolymerized PBT and PC. If the content of PC (B3-2) is 50% by mass or less, it is preferable because moldability is excellent. From this point of view, the content of PC in the total 100% by mass of copolymerized PBT and PC is preferably 50% by mass or less, especially 5% by mass or more or 40% by mass or less, and among them 5% by mass or more or 30% by mass. % by mass or less is more preferable.

(Copolymerized PBT + aromatic vinyl resin)
When the copolymerized PBT-based mixed resin (A4) contains the copolymerized PBT and the aromatic vinyl-based resin, the content of the aromatic vinyl-based resin is It is preferably 50% by mass or less. If the content of the aromatic vinyl resin is 50% by mass or less, it is preferable because moldability is excellent. From this point of view, the content of the aromatic vinyl resin in the total 100% by mass of the copolymerized PBT and the copolymerized PBT is preferably 50% by mass or less, especially 5% by mass or more or 45% by mass or less. It is more preferably 5% by mass or more or 40% by mass or less.

[Transmission side member]
The transmission side member that transmits laser light is a member made of a resin composition containing a thermoplastic polyester resin (A) and a laser light transmission and absorption color material, and transmits at least a portion of the laser light and a portion of the laser light. absorb light.
Examples of laser light transmitting and absorbing coloring materials include azine-based materials such as nigrosine and aniline black, phthalocyanine-based materials, naphthalocyanine-based materials, porphyrin-based materials, quaterrylene-based materials, azo-based materials, azomethine-based materials, anthraquinone-based materials, squaric acid derivatives, immonium, and quinacridone-based materials. , dioxazine-based, diketopyrrolopyrrole-based, anthrapyridone-based, isoindolinone-based, indanthrone-based, perinone-based, perylene-based, indigo-based, thioindigo-based, quinophthalone-based, quinoline-based, triphenylmethane-based, etc. Dyes and pigments can be mentioned. One of these may be selected and used, or two or more may be used in combination.
In the present invention, the term "dye or pigment" means dye or pigment.
Among the above-mentioned laser light transmitting and absorbing color materials contained in the transmission side member, dyes and pigments (X) that mainly absorb laser light wavelengths and dyes and pigments that mainly transmit laser light are used in order to increase the degree of blackness. (Y) is preferably used in combination.
The dye or pigment (X) that mainly absorbs at the wavelength of the laser light preferably contains a condensed mixture of azine-based compounds having an azine skeleton. Nigrosine is preferred as a condensed mixture of azine-based compounds having an azine skeleton. By containing nigrosine, the transmission side member is also exothermically melted by the laser beam, and sufficient welding strength can be achieved even for a complicated shape that would be difficult to weld appropriately only by exothermic melting of the absorption side member alone.

Nigrosine is a mixture of azine-based compounds having an azine (Azine) skeleton, acts as a dye having laser light absorption properties, and has moderate absorption in the laser light range of 800 nm to 1200 nm. Nigrosine is C.I. I. Solvent Black 5 and C.I. I. Solvent Black 7 is a black azine-based condensation mixture as described in the Color Index.
Nigrosine can be synthesized, for example, by subjecting aniline, aniline hydrochloride and nitrobenzene to oxidation and dehydration condensation at a reaction temperature of 160 to 190° C. in the presence of iron chloride.

The content of the dye or pigment (X) such as nigrosine is preferably 0.001 to 0.6 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). When the content of the dye or pigment (X) is 0.001 parts by mass or more, nigrosine is evenly dispersed, laser light is absorbed, and the resin melts evenly, which is preferable. In addition, when the amount is 0.6 parts by mass or less, the laser beam is transmitted, and foaming due to decomposition of the resin is less likely to occur, which is preferable.
From this point of view, the content of the dye and pigment (X) is preferably 0.001 to 0.6 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A), especially 0.02 parts by mass or more. Alternatively, it is 0.3 parts by mass or less, more preferably 0.05 parts by mass or more or 0.1 parts by mass or less.

Examples of dyes and pigments (Y) that mainly transmit laser light include anthraquinone dyes and pigments, perinone dyes and pigments, and azomethine dyes and pigments.
The color of these dyes and pigments is determined by the absorption wavelength of light. (hereinafter also referred to as "yellow dye") and a combination of a red dye and pigment (hereinafter also referred to as a "red dye"), a combination of a purple dye and pigment (hereinafter also referred to as a "purple dye") and a yellow dye , dyes and pigments exhibiting green (hereinafter also referred to as “green dye”), red dyes, blue dyes, and dyes and pigments exhibiting brown (hereinafter also referred to as “brown dyes”). can.

Preferred blue dyes are anthraquinone dyes with maximum absorption wavelengths in the range of 590-635 nm. Anthraquinone dyes are usually blue oil-soluble dyes.
By combining this dye as the laser light transmitting and absorbing color material contained in the transmission side member, for example, the visibility is higher than that of the green anthraquinone dye. By combining a yellow dye, it is possible to obtain a coloring agent exhibiting a black color with high coloring power.
As an anthraquinone dye having a maximum absorption wavelength in the range of 590 to 635 nm, it is preferable to select one having a measured value (decomposition initiation temperature) of 300° C. or higher with a thermogravimetric analyzer TG/DTA in the presence of air.

Preferred anthraquinone dyes are C.I. I. Solvent Blue 97 (decomposition initiation temperature 320° C.), C.I. I. Examples include Solvent Blue 104 (decomposition start temperature: 320°C). One or more of them may be used. However, if the blending amount is too large, the molded product tends to bleed in a high-temperature atmosphere, and the heat discoloration property tends to deteriorate.
Examples of commercially available anthraquinone dyes include "NUBIAN (registered trademark) BLUE series" and "OPLAS (registered trademark) BLUE series" (both trade names, manufactured by Orient Chemical Industry Co., Ltd.).

As a preferable red dye, a perinone dye having good heat resistance is selected, and a red perinone dye having a maximum absorption wavelength in the range of 460 to 480 nm is exemplified. Specific examples of such perinone dyes include C.I. I. Solvent Red 135, 162, 178, 179 and the like can be used. One or more of them may be used. However, if the blending amount is too large, the molded product tends to bleed in a high-temperature atmosphere, and the heat discoloration property tends to deteriorate.
Commercially available red perinone dyes include, for example, "NUBIAN (registered trademark) RED series, OPLAS (registered trademark) RED series" (both trade names, manufactured by Orient Chemical Industry Co., Ltd.).

As a preferable yellow dye, an anthraquinone dye having good heat resistance is selected, and an anthraquinone dye having a maximum absorption wavelength in the range of 435 to 455 nm is suitable. Anthraquinone dyes with maximum absorption wavelengths in the range of 435-455 nm are usually yellow oil-soluble dyes.
Specific examples of yellow anthraquinone dyes are C.I. I. Solvent Yellow 163, C.I. I. Vat Yellow 1, 2, 3, etc. can be used. One or more of them may be used. One or more of them may be used. However, if the blending amount is too large, the molded product tends to bleed in a high-temperature atmosphere, and the heat discoloration property tends to deteriorate.
Commercially available yellow anthraquinone dyes include, for example, "NUBIAN (registered trademark) YELLOW series, OPLAS (registered trademark) YELLOW series" (both trade names, manufactured by Orient Chemical Industry Co., Ltd.).

Azomethine dyes are selected as preferred brown dyes. Examples thereof include dyes containing at least a 1:1 type azomethine nickel complex represented by the following formula (1).

[In Formula (1), R ¹ to R ⁸ are the same or different, and are a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a carboxy group, a hydroxy group, an amino group, an alkyl It is an amino group, a nitro group or a halogen atom. ]

Examples of alkyl groups having 1 to 18 carbon atoms in R ¹ to R ⁸ in formula (1) include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group and i-butyl group. , sec-butyl group, t-butyl group, n-pentyl group, neo-pentyl group, i-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-decyl group Examples of alkoxy groups having 1 to 18 carbon atoms include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, sec-butoxy, t-butoxy group, n-pentyloxy group, neo-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group and the like are preferred, and examples of alkylamino groups include methylamino group, A dimethylamino group, ethylamino, diethylamino and the like can be preferably mentioned, and halogen atoms are, for example, F, Cl, Br and the like.

The azomethine dye used for the 1:1 type azomethine nickel complex can be produced by a known method. For example, it can be obtained by reacting diaminomaleonitrile and salicylaldehyde, which may have a substituent, as shown in the following reaction formula.

In formula (2), R ¹ to R ⁸ have the same definitions as in formula (1).
By metallizing this azomethine dye with a nickeling agent such as nickel acetate, a 1:1 type azomethine nickel complex is obtained as shown below.

In formula (3), R ¹ to R ⁸ have the same definitions as in formula (1).
The resulting nickel complex forms a stable complex with the azomethine dye acting as a chelating tetraligand.

Since the 1:1 type azomethine nickel complex has good fastness such as heat resistance and light resistance, it is useful for resin compositions for outdoor members and members exposed to heat. is less likely to occur, and is suitable as a coloring agent for laser-welded members.

Specific examples of the 1:1 type azomethine nickel complex represented by the formula (1) include compounds 1 to 7 in Table 1 below, in which R ¹ to R ⁸ are as follows.
In addition, the azomethine nickel complex used as the above-mentioned laser light transmitting and absorbing coloring material contained in the transmission side member is not limited to these.

When the transmission-side member contains a dye or pigment (Y) that mainly transmits the laser light used as the laser light transmission/absorption color material, an anthraquinone dye or pigment (C1) having a maximum absorption wavelength in the range of 590 to 635 nm It is preferable to use a perinone dye (C2) having a maximum absorption wavelength in the range of 460-480 nm and an anthraquinone dye (C3) having a maximum absorption wavelength in the range of 435-455 nm.
Due to the compatibility with the thermoplastic polyester resin (A), the dye and pigment (X), which is a dye and pigment that mainly absorbs at the laser light wavelength, and the dye and pigment (Y) that constitutes the dye and pigment that mainly transmits the laser light. Since the hue changes, it is desirable to adjust the ratio of each dye constituting the dye/pigment (Y) in order to obtain a jet-black molded plate suitable for a black hue. In that case, the content ratio of C1 to C3 is preferably C1:C2:C3=24 to 42:24 to 48:22 to 46 (based on a total of 100 parts by mass of C1, C2, and C3). . A more preferred C1:C2:C3 ratio is 24-41:24-39:22-46.

Furthermore, the dyes and pigments (Y) that mainly transmit the laser light used as the laser light transmission and absorption color material contained in the transmission side member are perinone dyes and pigments (C2) having a maximum absorption wavelength in the range of 460 to 480 nm and The colorant preferably contains an anthraquinone dye (C1) having an absorption wavelength in the range of 590 to 635 nm in a mass ratio C2/C1 of 0.4 to 2. Taking into consideration the color developability of the resin composition used in the present invention and the suppression of bleeding out, it is more preferably 0.4 to 1.5, still more preferably 0.6 to 1.5.
Other dyes and pigments that may be used in combination include azo-based, quinacridone-based, dioxazine-based, quinophthalone-based, perylene-based, perinone-based (compounds having wavelengths different from C2 described above), isoindolinone-based, triphenylmethane-based, Anthraquinone-based dyes and pigments (compounds with different wavelengths from C1 and C3 described above) and azomethine-based dyes and pigments can be used. However, it is preferable not to contain nickel.

The content of the laser light transmitting and absorbing coloring material is preferably 0.0005 to 5.0 parts by mass with respect to 100 parts by mass of the polyester resin material (A). If the content of the transmission absorption coloring material is 0.0005 parts by mass or more, the resin absorbs the laser light and melts, which is preferable. On the other hand, if the content is 5.0 parts by mass or less, bleeding out of the dye and pigment can be suppressed and the amount of heat generated can be controlled, which is preferable.
From this point of view, the content of the laser light transmitting and absorbing coloring material is preferably 0.0005 to 5.0 parts by mass, more preferably 0.001 part by mass or more or 4.0 parts by mass, relative to the polyester resin (A). 0 parts by mass or less, more preferably 0.005 parts by mass or more or 3.0 parts by mass or less.

As described above, when the dye/pigment (X) that mainly absorbs the laser light wavelength and the dye/pigment (Y) that mainly transmits the laser light are combined as the laser light transmission/absorption color material, the dye/pigment (X ) is preferably 0.0005 to 0.6 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A).
If the content of the dye (X) is 0.0005 parts by mass or more, the absorbing dye and pigment are evenly dispersed, and the resin absorbs the laser light and melts evenly, which is preferable. On the other hand, if the content is 0.6 parts by mass or less, the laser beam is transmitted, and foaming due to decomposition of the resin is less likely to occur, which is preferable.
From this point of view, the content of the dye or pigment (X) is preferably 0.0005 to 0.6 parts by mass, especially 0.001 part by mass, with respect to 100 parts by mass of the thermoplastic polyester resin (A). 0.3 parts by mass or less, more preferably 0.003 parts by mass or more and 0.1 parts by mass or less.

The dye or pigment (Y) that mainly transmits laser light is preferably 0.0005 to 5 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A).
If the content of the dye or pigment (Y) that mainly transmits laser light is 5.0 parts by mass or less, bleeding out of the dye and pigment hardly occurs, which is preferable.
From this point of view, the content of the dye and pigment (Y) that mainly transmits laser light is preferably 0.0005 to 5 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). 0.05 parts by mass or more or 4 parts by mass or less, more preferably 0.1 parts by mass or more or 3 parts by mass or less.
The ratio (Y/X) of dye/pigment (Y) content to dye/pigment (X) content is preferably 1 to 100, especially 10 or more or 90 or less, especially 20 or more or 80 or less. is more preferred.

[Absorption side member]
The absorption side member is made of a resin composition containing 0.001 to 0.15 parts by mass of a laser light absorbing coloring material with respect to 100 parts by mass of the thermoplastic polyester resin (A). Examples of the laser light absorbing color material include black colorants such as carbon black, and white colorants such as titanium oxide and zinc sulfide. be able to. Among them, those containing carbon black are preferable.

As carbon black, at least one of furnace black, thermal black, channel black, lamp black, acetylene black and the like can be used alone, or two or more of them can be used in combination.
In order to facilitate dispersion of carbon black, it is also preferable to use one that has been masterbatched in advance with the resin component constituting the thermoplastic polyester resin (A) or other resins.

From the viewpoint of dispersibility, the primary particle size of carbon black is preferably 10 nm to 30 nm, more preferably 15 nm or more and 25 nm or less. Good dispersibility reduces welding unevenness during laser welding.
In addition, from the viewpoint of jet blackness, the carbon black preferably has a nitrogen adsorption specific surface area of 30 to 400 m ² /g, especially 50 m ² /g or more, especially 80 m ² /g or more, as measured by JIS K6217. is more preferred.

Furthermore, from the viewpoint of dispersibility, the carbon black preferably has a DBP absorption of 20 to 200 cm ³ /100 g, more preferably 40 to 170 cm ³ /100 g, further preferably 50 to 150 cm 3 /100 ^g , as measured by JIS K6221. 100 g is preferred. Good dispersibility reduces welding unevenness during laser welding.

The content of the laser light absorbing coloring material such as carbon black is, as described above, 0.001 to 0.15 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). If the content of the laser light absorbing coloring material is 0.001 parts by mass or more, the resin heats up and melts during laser irradiation. can be done. The content of the laser light absorbing color material is 0.001 or more and less than 0.15 parts by mass, and 0.005 parts or more and 0.1 parts or less by mass, with respect to 100 parts by mass of the thermoplastic polyester resin (A). is preferred, and more preferably 0.01 parts by mass or more and 0.08 parts by mass or less.

In addition, the absorption side member can appropriately contain components other than the thermoplastic polyester resin (A) and the laser light absorbing coloring material.

Other components include laser light transmitting and absorbing coloring materials such as nigrosine. The absorption side member may or may not contain a laser light transmitting and absorbing coloring material such as nigrosine. By not containing a laser light transmitting and absorbing coloring material, particularly nigrosine, it is possible to prevent heat-resistant discoloration and light-resistant discoloration.
Nigrosine is as described above. When the absorbent member contains nigrosine, the content is preferably 0.001 to 0.6 parts by mass with respect to 100 parts by mass of the thermoplastic polyester resin (A). When the content of nigrosine is 0.001 parts by mass or more, nigrosine is uniformly dispersed and the resin uniformly melts by absorbing laser light, which is preferable. The content of nigrosine is more preferably 0.02 to 0.3 parts by mass, since it can transmit as much as possible and suppress foaming due to decomposition of the resin caused by excessive absorption of laser light. 05 to 0.1 parts by mass is more preferable.

[Other ingredients]
The permeation side member and the absorption side member can contain various additives other than the components described above as desired. Such additives include, for example, reinforcing fillers, impact modifiers, flow modifiers, color auxiliaries, dispersants, stabilizers, plasticizers, UV absorbers, light stabilizers, antioxidants, antistatic agents, Inhibitors, lubricants, release agents, crystallization promoters, nucleating agents, flame retardants, epoxy compounds, and the like can be mentioned.

[Shape of member]
The shape of the member is arbitrary. For example, it may be plate-shaped, rectangular, or have other complicated shapes. For example, profiled extruded products (bars, pipes, etc.) whose ends are butted for welding may be used, and metal-inserted molded products used for current-carrying parts and electronic parts that require high waterproofness and airtightness. There may be.

The method of forming the member is also arbitrary. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, blow molding method such as gas assist, molding method using heat insulating mold, molding method using rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding, extrusion molding, sheet molding, thermoforming, rotational molding, laminate molding, press molding, blow molding, etc. can be mentioned.

Since the transmission side member needs to transmit the laser light over its entire thickness, it is not preferable that the transmission side member is too thick. On the other hand, if it is too thin, the strength of the molded product will be weak, which is not preferable.
From this point of view, the thickness of the laser welded joint of the transmitting side member is preferably 0.2 mm to 7.0 mm, more preferably 0.4 mm or more or 6.5 mm or less, and more preferably 0.5 mm or more or 6.5 mm or less. 0 mm or less is more preferable.

[Relationship between transmission-side member and absorption-side member]
From the viewpoint of bonding strength, the difference between the transmission side member and the absorption side member ((Tm−A)−(Tc−A)) between the melting point Tm−A and the crystallization temperature Tc−A of the transmission side member is the absorption More preferably, it is larger than the difference ((Tm-B)-(Tc-B)) between the melting point Tm-B and the crystallization temperature Tc-B of the side member. In particular, ((Tm-A)-(Tc-A))-((Tm-B)-(Tc-B)) is in the range of 0 to 30° C., although it is strongly affected by the resin used for the absorption side member. Among them, the range of 2 to 20°C is more preferred, the range of 3 to 15°C is more preferred, and the range of 4 to 10°C is even more preferred.
In order to do so, for example, adjustment of the mixing ratio of the thermoplastic polyester resin (A) used for the absorption side member, selection of various additives and adjustment of the blending amount, and adjustment of the blending amount of the thermoplastic polyester resin used for the transmission side member It is only necessary to select the laser light transmitting and absorbing dye (A) and adjust the blending amount. However, it is not limited to these adjustment methods.

Further, from the viewpoint of bonding strength, the melting enthalpy ΔHm-A of the transmission side member and the melting enthalpy ΔHm-B of the absorption side member are determined by the thermoplastic polyester used for the absorption side member. It is more preferably higher than the melting enthalpy ΔHm-B of the system resin (A). (ΔHm−A)−(ΔHm−B) is preferably in the range of 0 to 20 J/g, more preferably in the range of 0.5 to 10 J/g, more preferably in the range of 2 to 9 J/g.
In order to do so, for example, adjustment of the mixing ratio of the thermoplastic polyester resin (A) used for the absorption side member, selection of various additives and adjustment of the blending amount, and adjustment of the blending amount of the thermoplastic polyester resin used for the transmission side member It is only necessary to select the laser light transmitting and absorbing dye (A) and adjust the blending amount. However, it is not limited to these adjustment methods.
The melting point Tm, the crystallization temperature Tc, and the melting enthalpy ΔHm were determined by cutting out a sample of the transmission-side member and the absorption-side member molded by injection molding at a distance of 5 mm or more from the gate of the injection molding die. Measured and asked.

[Manufacturing method of laser welded product]
The thermoplastic polyester resin (A) used for the permeation side member and the absorption side member may be produced by preparing a resin composition by a conventional method and molding the resin composition by a conventional method.
For example, raw materials constituting the permeation side member or the absorption side member may be mixed and melt-kneaded by a single-screw or twin-screw extruder. Alternatively, the resin composition may be prepared without pre-mixing the respective components, or pre-mixing only a part of them, supplying the components to an extruder using a feeder, and melt-kneading them.

A part of the resin constituting the permeation side member or the absorption side member is blended with a part of another resin to prepare a masterbatch, which is then blended with the rest of the resin and other components. may be melt-kneaded.
When a fibrous reinforcing filler such as glass fiber is used, it is also preferable to supply it from a side feeder in the middle of the cylinder of the extruder.

The heating temperature for melt-kneading can be appropriately selected from the range of 220 to 300°C. If the temperature is too high, decomposition gas is likely to be generated, which may cause opacification. Therefore, it is desirable to select a screw structure in consideration of shear heat generation and the like. In order to suppress decomposition during kneading and subsequent molding, it is desirable to use antioxidants and heat stabilizers.

Any method can be adopted as a method for forming the transmission side member and the absorption side member.
For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, blow molding method such as gas assist, molding method using heat insulating mold, molding method using rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding, extrusion molding, sheet molding, thermoforming, rotational molding, laminate molding, press molding, blow molding, etc. can be mentioned.

[Laser welding]
In laser welding, the transmission side member and the absorption side member formed by injection molding or the like of the thermoplastic polyester resin material described above are brought into surface contact or point contact, and a laser beam is irradiated from the transmission side member side. are at least partially melted and integrated into one molded product.

The shapes of the transmission-side member and the absorption-side member themselves are not limited as long as they can be joined by laser welding. It is good, but it does not have a convex structure, and has concave portions with a depth of 0.1 μm or more on the joint surfaces of the transmission-side member and/or the absorption-side member. The recess is preferably not intentionally installed, but may be generated by molding shrinkage or the like, and the specific shape thereof is not limited. For example, the depth of the center of the recess is 0.1 μm In addition, the thickness is preferably 500 μm or less, more preferably 1 μm or more and 100 μm or less, and still more preferably 1 μm or more and 50 μm or less. It is difficult to obtain a molded product with recesses less than this, and it is difficult to obtain sufficient welding strength if it is more.

The depth of the recesses can be adjusted within the above range by appropriately combining various molding conditions such as cylinder temperature, mold temperature, injection speed, holding pressure, holding pressure time, and cooling time. Further, by designing the resin composition, the shape and/or the size of the molded product, the gate position, the gate diameter, etc., it is possible to greatly adjust.
Here, the recess is expressed as the joint surface in the mold drawing as a reference plane, and the depth of the recess is within a range of 10 mm in length and width with respect to the reference plane in order to obtain the depth of the part hit by the laser beam. point to

In addition, the convex structure is, but is not limited to, a structure having a height of 0.5 mm or more, for example. It means a projection shape, a fitting shape, and other shapes provided in the. Moreover, even if it is unintentional, it means something that exists on and/or in the vicinity of the joint surface and directly and/or indirectly contributes to the welding.

Hereinafter, the method for producing a laser-welded article according to the present invention will be described with reference to the drawings.
FIG. 1 is an overview diagram showing an example of the method for producing a laser-welded body of the present invention. The absorption side member 1 has, for example, a cylindrical shape with a bottom as shown in FIG. It serves as a lid, and its lower surface is in surface contact with the joint surface 3 of the absorption side member 1 .

As described above, the shapes of the transmission-side member and the absorption-side member themselves are not limited as long as they can be joined by laser welding. ) viewed from the side of the transmission-side member, it may have a shape with an axis of symmetry, such as concentric circles or squares as shown in FIG. 1, or it may have a complex shape with no axis of symmetry. , the outline of the shape of the joining portion of the shape of the absorption side member may be composed of two or more lines selected from the group consisting of a plurality of curves having different curvatures and straight lines.
Further, the transmission-side member may have the same size and shape as the joint portion of the absorption-side member, or may be larger than the joint portion of the absorption-side member, or may have a different shape.
According to the present invention, since the transmission side member is also exothermically melted, it is possible to obtain a sufficient welding strength even with a complicated shape in which proper welding is difficult when only the absorption side member is exothermically melted.

In addition, the height difference of the joint surface is caused by various factors. Caused by factors. In addition, the influence may affect the entire molded product, or it may affect details such as the joint surface. In order to obtain sufficient welding strength, it is desirable to minimize this height difference, and this is possible by optimizing the combination of the resin composition, molding conditions, annealing conditions, and the like. The height difference indicates the difference from the highest part to the lowest part with respect to the reference plane in the entire line to be welded. The height difference is not constant in the line to be welded, but continuously changes.
Since the difference in height is also related to the allowable range in designing the molded product and the manufacturing cost, it may be necessary to allow a difference in height above a certain level. According to the method of the present invention, it is possible to achieve sufficient welding strength even if there is a height difference of 0.01 mm or more.
The height difference between the joint surfaces is preferably 0.01 to 0.5 mm, more preferably 0.02 to 0.4 mm, and still more preferably 0.05 to 0.3 mm.

Sink marks and warpage may occur in either the transmission side member or the absorption side member, or may occur in both. Furthermore, if it occurs in both parts, it is expressed as a gap when both parts are superimposed under no pressure, and these can be detected using special checking tools, or simply as gap gauges, dial gauges, and height gauges. Measure by using a dial gauge together.
Measurement is taken as the distance from the reference plane to the joint surface, with three points on the transmission side and/or the absorption side member as reference planes.

The transmittance of the transmission-side member is not particularly limited as long as at least part of the laser beam can be transmitted therethrough. is 15 to 80%, more preferably 20 to 70%.
Transmittance does not differ greatly if it is a test piece shape such as JIS standard, but in a practical product shape, there are places where the transmittance is high and places where it is low depending on the gate position of the molded product and the shape of the molded product. The transmittance is often not completely uniform, and the laser light transmittance at the joint of the transmission-side member is often partially different and continuously changing. If the transmittance is different, the welding strength tends to vary when welding is performed at the same output and the same scanning speed. It is possible to obtain good welding strength even with the product.

The type of laser beam irradiated for laser welding is not particularly limited, but can be selected from solid laser, fiber laser, semiconductor laser, gas laser, liquid laser, and the like. For example, YAG (yttrium aluminum garnet crystal) laser (wavelength 1064 nm, 1070 nm), LD (laser diode) laser (wavelength 808 nm, 840 nm, 940 nm, 980 nm), etc. can be preferably used. In particular, laser beams with wavelengths of 940 nm, 980 nm and 1070 nm are preferred. The oscillation form may be either CW or pulse. There are no particular restrictions on the irradiation method, and the laser head is moved by a robot, the galvano scan method that scans the laser light by reflecting it with a mirror, and the method that is equipped with multiple laser heads and irradiates the welding surface at the same time. It can be selected as appropriate.

The laser spot diameter is preferably 0.1 mm or more and 30 mm or less, more preferably 0.2 mm or more and 10 mm or less, still more preferably 0.3 mm or more and 5 mm or less, and particularly preferably 1.5 to 3.0 mm. If it is less than this, welding tends to be difficult, and if it is more than this, it becomes difficult to control the welding width. Moreover, it is preferable to select the spot diameter of the laser beam according to the shape of the joint surface.
Also, the laser beam may be focused on the joint surface or may be defocused.

Welding conditions are not particularly limited, and vary depending on the specifications of the apparatus, and various selections can be made depending on the combination of laser type, laser diameter, laser output, and scanning speed. 10W to 500W, more preferably 15W to 200W. If the output is higher than this, the cost of laser welding equipment tends to increase, and if it is lower than this, it is likely to be difficult to obtain sufficient welding strength.
The laser scanning speed is 0.1 mm/s to 20000 mm/s, preferably 1 mm/s to 10000 mm/s, more preferably 10 mm/s to 1000 mm/s.
As for the laser scanning method, the output and scanning speed can be varied in accordance with changes in the state of the joint surface, which is more preferable in terms of welding efficiency, welding strength, welding appearance, and apparatus load.

In carrying out laser welding, first, the transmission side member 2 and the absorption side member 1 are overlapped at their joint surfaces 3, and the state in which the transmission side member 2 and the absorption side member 1 are overlapped is maintained. When maintaining the superimposed state, a transparent plate material such as a glass plate, a quartz plate, or an acrylic plate may be arranged on the transmission side member 2, that is, on the laser irradiation side. In particular, when a glass plate or a quartz plate is arranged, it is suitable for facilitating the dissipation of heat generated during laser welding and obtaining a good appearance.
Next, a laser beam X is scanned and irradiated from above the transmission side member 2 onto the welding line 4 corresponding to the peripheral edge of the absorption side member 1 . At this time, most or most of the laser light X is transmitted through the transmission side member 2 . Then, the laser beam X is absorbed by the joining surface of the absorption side member 1, and the vicinity of the surface generates heat and melts. In addition, it is preferable to apply a pressing force (N/mm) per unit distance to both members by a jig or pressure means at least when joining the two members by laser welding. This pushing force is preferably 80 N/mm or less, more preferably 0.0002 to 80 N/mm. By doing so, the joint surface of the absorption side member 1 and the transmission side member are fused together, and after the irradiation of the laser beam X is stopped, the melted portions of the transmission side member 2 and the absorption side member 1 are cooled, After solidification, both members are welded and integrated with high strength. The upper limit of the pressing force per unit distance is more preferably 70 N/mm or less, particularly preferably 50 N/mm or less, further preferably 20 N/mm or less, especially 10 N/mm or less, most preferably 5 N/mm or less. If the pressure is too strong, residual stress tends to remain in the molded product, and height difference tends to increase due to warping deformation, which tends to cause smoke or fail to obtain sufficient welding strength.
Also, the pressing force per unit distance is preferably 0.4 N/mm or more. If the thickness is less than this, the adhesion between the joint surfaces cannot be maintained, and welding may become difficult.
The pressing force per unit distance at the time of joining the two members by laser welding can be obtained by dividing the actual pressing force (N) by the length (mm) of one circumference of the line to be welded.

The scanning of the laser beam X may be performed by making one round toward the joint surface 4 at the peripheral edge of the absorbing member 1, or may be carried out by making two or three rounds or more of round scanning. If the scanning of the laser beam X deviates from the joint surface 3, which is the line 4 to be welded, smoke occurs and welding becomes difficult, so selection of the scanning position is important.

According to the method for producing a laser welded body of the present invention, it is possible to obtain a welded body having high bonding strength. The bonding strength of the weld body according to the present invention is preferably 1500 N or more, more preferably 1600 N or more, and even more preferably 1700 N or more.

The laser-welded body manufactured according to the present invention is capable of enhancing the airtightness of the welded portion. For airtightness, for example, the compression strength of a compact welded under a pressing force per unit distance of 4.5 N/mm is preferably 1200 kPa or more, more preferably 1300 kPa or more.

[Laser welded product manufacturing kit]
The method for producing a laser-welded body of the present invention is characterized in that the bonding surfaces do not have a convex structure, and at least one of the bonding surfaces has recesses with a depth of 0.1 μm or more. A transmission-side member made of a composition containing a light-transmitting and absorbing coloring material, and an absorbing member made of a composition containing 0.001 to 0.15 parts by mass of a laser light-absorbing coloring material with respect to 100 parts by mass of a thermoplastic polyester resin. The side members are used as a set. That is, the transmitting side member is made of a composition containing a laser light transmitting and absorbing coloring material in a thermoplastic polyester resin, and the absorption side member contains 0.001 part of the laser light absorbing coloring material per 100 parts by mass of the thermoplastic polyester resin. 0.15 parts by mass of the composition, each bonding surface of both members does not have a convex structure, and the bonding surface of the transmission-side member and/or the absorption-side member has a depth of 0 A kit for manufacturing a laser-welded body characterized by having recesses of 0.1 μm or more is also one of the embodiments of the present invention.

The shape, size, thickness, etc. of the molded product integrated by laser welding are arbitrary. Applications of the welded product include electrical parts for transportation equipment such as automobiles, electrical and electronic equipment parts, industrial machine parts, and others. It is particularly suitable for consumer parts and the like. In addition, the welding strength is high, and as a result, the pressure resistance is also high. Therefore, it is necessary to have airtightness for the container, etc. for incorporating electric and electronic parts such as electronic boards, circuits, sensors, solenoids, motors, transformers, batteries, etc. inside. It is also preferable to use it for various purposes.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the following examples.

[Manufacture of absorption side members A to C]
Each component described in Table 2 below is blended in the amount described in Absorption side composition A to C in Table 2 (all parts by mass), and kneaded at 250 ° C. using a 30 mm vent type twin screw extruder. The strands were extruded with a squeegee to obtain pellets of absorber compositions A to C.

After drying the obtained pellets of the absorption side compositions A to C at 120 ° C. for 7 hours, an injection molding machine ("J55" manufactured by Japan Steel Works, Ltd.) was used to mold the cylinder temperature to 260 ° C., the mold temperature to 80 ° C., At an injection speed of 60 mm/s, a holding pressure of 70 MPa, a holding pressure time of 5 s, and a cooling time of 15 s, a cylindrical absorber (48 mm in diameter, 20 mm in height, and 5 mm in width of the joint surface 3) as shown in the absorption side member 1 in FIG. Side members A to C (without protrusions) were injection molded. The shape of the molded product was designed so that the gate position was the center of the bottom surface of the cylindrical shape, the pin gate had a gate diameter of φ 1.2 mm, and the welding surface 3 was near the flow end of the resin. As shown in FIG. 2(a), no protrusions are provided on the bonding surface 3, and the average depth of the recesses formed is 65 μm, 62 μm, and 70 μm for the absorption side members A, B, and C, respectively. Met. For the depth of the concave portion, a 3D image of the welded portion of each of the absorption side members A to C was acquired at 90° intervals using the KEYENCE 3D shape measuring machine "VR-3200", and the attached analysis software was used to measure the maximum depth of the recess, and the average value was taken.
Also, on the joint surface 3, as shown in FIG. As shown in (c), two rows (double) of protrusions (protrusions) with a height of 0.7 mm and a width of 0.5 mm are provided in parallel with an interval of 0.5 mm between the protrusions. Molding was carried out in the same manner as above except that the shape was changed.

[Methods for measuring melting point Tm, crystallization temperature Tc, and melting enthalpy ΔHm]
The part to be welded (distance from the gate: 42 mm part) of the formed body of the absorption side member was cut, and a differential scanning calorimeter (DSC) machine ("Pyris Diamond" manufactured by Perkin Elmer) was used to measure the temperature under a nitrogen atmosphere. , the temperature was raised from 30 ° C. to 300 ° C. at a temperature increase rate of 20 ° C./min, held at 300 ° C. for 3 minutes, and then cooled at a temperature decrease rate of 20 ° C./min. was measured.

[Production of Transmission Side Members D-1 to D-4, E]
Dyes and pigments (Y-1) to (Y-3) containing the components shown in Table 3 below in the proportions shown in Table 3 were used in the production of the transmission side member.

Each component described in Table 3 and Table 4 below is blended in the amounts (parts by mass) described in the transmission side compositions D-1 to D-4 and E in Table 4, and this is blended with a 30 mm vent type 2 Using a screw extruder, the mixture was kneaded at 250° C. and extruded into strands to obtain pellets of permeable material compositions D-1 to D-4 and E.

After drying the obtained pellets of the permeable material compositions D-1 to D-4 and E at 120° C. for 7 hours, an injection molding machine (manufactured by Japan Steel Works, Ltd. “J55”) was used at a cylinder temperature of 260° C., gold Injection molding was performed at a mold temperature of 80° C. to produce disk-shaped transmission side members D-1 to D-4 and E having a diameter of 48 mm and a thickness of 1.5 mm.

[Methods for measuring melting point Tm, crystallization temperature Tc, and melting enthalpy ΔHm]
The part to be welded (distance from the gate: 33 mm part) of the formed body of the transmission side member was cut, and a differential scanning calorimeter (DSC) machine ("Pyris Diamond" manufactured by PerkinElmer) was used to measure the temperature under a nitrogen atmosphere. , the temperature was raised from 30 ° C. to 300 ° C. at a temperature increase rate of 20 ° C./min, held at 300 ° C. for 3 minutes, and then cooled at a temperature decrease rate of 20 ° C./min. was measured.

[Laser welding evaluation]
(Examples 1 to 3, 5, Reference Example 4, Comparative Examples 1 to 5)
Any one of the transmission side members D-1 to D-4 and E obtained above is placed on the transmission side, and among the absorption side members A to C, there is no convex portion, with a single convex portion, or with a double convex portion. With one of them on the absorption side, the combination shown in Table 5 is overlapped and pressed, and a laser beam X is irradiated from above the transmission side member 2 toward the joining surface 3 of the absorption side member 1 to weld. Scanning was performed so as to make a turn (the number of turns was 1) along the planned line 4, and laser welding was performed.
Examples 1 and 2 and Comparative Example 3 are the same except that the carbon black concentration of the absorbent is different. Example 3 and Reference Example 4 are the same as Example 2 except that the composition of the dye and pigment is different. Example 5 is the same as Example 1 except that the resin composition of the transmission side member is different. Comparative Example 1 is the same as Example 1 except that it has a single convex portion and Comparative Example 2 has a double convex portion. Comparative Example 4 is the same as Example 1 except that the transparent material does not contain a laser light absorbing coloring material such as nigrosine. Comparative Example 5 is the same as Example 5 except that it has a double convex portion.

For laser welding, a laser device manufactured by Fine Devices (laser wavelength: 940 nm, laser spot diameter φ2.1 mm, maximum output 140 W, maximum scanning speed 200 mm/s) was used. Various welding conditions are shown in Table 5.
The pressing force (N / mm) per unit distance in Table 5 was measured by placing a coin-shaped load cell (LM- 20 kN) was set, and the actual applied pressure was measured. A value obtained by dividing the obtained pressurizing force (N) by the length (mm) of one circumference of the line to be welded was used.

The laser welding strength of the welded body was measured. The bonding strength of the weld body was measured using a tensile tester ("1t Tensilon" manufactured by Orientec), and a tensile bar was attached to a test jig that had been inserted into the weld body before welding. It was evaluated by pulling at 5 mm/min from the transmission side member side.
In addition, the presence or absence of smoke generation during welding was visually observed.

Furthermore, airtightness was evaluated as follows.
For airtightness measurement, the transmitting side member had a diameter of 48 mm, a diameter of 48 mm, a Transmission side members D-1 to D-4 and E with a thickness of 1.5 mm were manufactured. By using the transmission side member having this convex portion, welded bodies of Examples 1 to 5 and Comparative Examples 1 to 5 were obtained. A hole of Φ3.5 mm was made in the location of the convex portion at the center of the transmitting side member of the obtained weld body, and then a coupler for water injection was joined.
First, the interior of the welded body was filled with water, and then immersed in water at 25°C. Next, water is supplied to the interior of the welded body, and the internal pressure of the welded body is increased in increments of 196 kPa.
In addition, the device used was a "bottle pressure resistance tester" manufactured by Toyo Seiki Co., Ltd.
The above results are shown in Table 5 below.

As described above, in Examples 1 to 5, no smoking was confirmed, and very high welding strength was obtained even with a low applied pressure. On the other hand, in Comparative Examples 1 and 2, sufficient welding strength was not obtained. Moreover, in Comparative Example 3, even when the bonding surface did not have a convex portion, the absorption material had a high carbon black concentration, and as a result, excessive heat generation occurred more than required for welding, resulting in decomposition of the resin. Smoke generation was confirmed, and welding could not be performed. Furthermore, in Comparative Example 4, since a conventional transmissive material that does not contain a laser light absorbing material is used, even if the joint surface does not have a convex portion, smoke does not occur, but the gap between the joint surfaces can be sufficiently filled. and could not be welded. In Comparative Example 5, sufficient bonding strength was not obtained due to the presence of the convex portion, whereas in Example 5, good bonding strength was obtained. Further, although sufficient airtightness was maintained in Examples 1 to 5, the airtightness was insufficient in all of the comparative examples.

The method for producing a laser-welded body of the present invention enables laser welding with stable high welding strength even for polyester members with gaps on the joint surface. It can be suitably used for manufacturing equipment parts, industrial machine parts, and other consumer parts. In addition, the welding strength is high, and as a result, the pressure resistance is also high. Therefore, it is necessary to have airtightness for the container, etc. for incorporating electric and electronic parts such as electronic boards, circuits, sensors, solenoids, motors, transformers, batteries, etc. inside. It is also preferable to use it for various purposes.

1: absorption side member 2: transmission side member 3: joint surface 4: planned welding line X: laser beam

Claims (4)

A method for manufacturing a laser-welded body in which a transmission side member that transmits at least a part of laser light and an absorption side member that absorbs laser light are laser-welded via a joint surface,
The transmission side member is made of a composition containing a coloring material capable of transmitting and absorbing laser light with respect to a thermoplastic polyester resin (referred to as a "laser transmission and absorption coloring material"), and the absorption side member is thermoplastic. A composition containing 0.001 to 0.15 parts by mass of a coloring material that can absorb laser light without transmitting it (referred to as a "laser light absorbing coloring material") with respect to 100 parts by mass of polyester resin,
The difference between the melting point Tm−A and the crystallization temperature Tc−A of the transmission side member [(Tm−A)−(Tc−A)] and the difference between the melting point Tm−B and the crystallization temperature Tc−B of the absorption side member [ The difference [(Tm-A)-(Tc-A)]-[(Tm-B)-(Tc-B)] from (Tm-B)-(Tc-B)] is 2 to 10 ° C.,
The joint surface between the transmission-side member and the absorption-side member does not have a convex structure, and the joint surface of the transmission-side member and/or the absorption-side member has a concave portion with a depth of 0.1 μm or more. A method for manufacturing a laser welded body characterized by: 2. The method for producing a laser-welded body according to claim 1, wherein the laser light transmitting and absorbing coloring material is nigrosine, and the laser light absorbing coloring material is carbon black. A kit for manufacturing a laser-welded body, comprising a transmission side member that transmits at least a part of laser light and an absorption side member that absorbs laser light,
The transmitting side member is made of a composition containing a laser light transmitting and absorbing coloring material in a thermoplastic polyester resin, and the absorption side member contains 0.001 to 0.001 to 0 of the laser light absorbing coloring material with respect to 100 parts by mass of the thermoplastic polyester resin. .15 parts by mass of a composition containing
The difference between the melting point Tm−A and the crystallization temperature Tc−A of the transmission side member [(Tm−A)−(Tc−A)] and the difference between the melting point Tm−B and the crystallization temperature Tc−B of the absorption side member [ The difference [(Tm-A)-(Tc-A)]-[(Tm-B)-(Tc-B)] from (Tm-B)-(Tc-B)] is 2 to 10 ° C.,
Laser welding characterized in that each bonding surface of both members does not have a convex structure, and a concave portion having a depth of 0.1 μm or more is provided on the bonding surface of the transmission-side member and/or the absorption-side member. Body building kit. 4. The kit for producing a laser-welded body according to claim 3, wherein the laser light transmitting and absorbing coloring material is nigrosine and the laser light absorbing coloring material is carbon black.

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