CN111278633A

CN111278633A - Method for manufacturing laser welded body

Info

Publication number: CN111278633A
Application number: CN201880070960.1A
Authority: CN
Inventors: 冈明宏; 宇尾野宏之; 樋渡有希; 山中康史
Original assignee: Mitsuba Corp; Mitsubishi Engineering Plastics Corp
Current assignee: Mitsuba Corp; Mitsubishi Chemical Corp
Priority date: 2017-10-31
Filing date: 2018-10-30
Publication date: 2020-06-12
Also published as: JP7145167B2; WO2019088058A1; JPWO2019088058A1

Abstract

A method for producing a laser welded structure, comprising laser welding a transmission-side member for transmitting at least a part of a laser beam and an absorption-side member for absorbing the laser beam with a joint surface interposed therebetween, wherein the joint surface has a shape free from a symmetry axis, the transmission-side member is formed of a composition containing a thermoplastic polyester resin and a coloring material capable of transmitting and absorbing the laser beam, and the absorption-side member is formed of a composition containing a thermoplastic polyester resin and a coloring material capable of absorbing the laser beam and not transmitting the laser beam, wherein the welding is performed while applying a thrust per unit distance of 10N/mm or less between the two members.

Description

Method for manufacturing laser welded body

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 members formed of a polyester resin and having a welding joint surface of a complicated shape are laser welded with a stable high welding strength.

Background

In recent years, automobile parts and consumer parts have been made resin-molded and resin-molded products made smaller in size, which have been conventionally made of metal, from the viewpoint of environmental protection such as weight reduction and recycling. Polyester resins are widely used for various device parts because they are excellent in mechanical strength, chemical resistance, electrical insulation, and the like, and also excellent in heat resistance, moldability, and recyclability. Particularly, thermoplastic polyester resins such as polybutylene terephthalate resins are widely used for electric and electronic equipment parts and the like which require flame-retardant safety because they are excellent in mechanical strength and moldability and can be made flame-retardant.

These equipment parts are provided with a space therein to house an electronic circuit, a driving portion such as a motor or a fan, an electronic circuit, a connector, and the like, and molded articles used for these are manufactured by dividing the molded articles into a plurality of resin members and joining the resin members, whereby weight reduction and optimization of shape by hollowing can be achieved as compared with the case of integral molding.

As a method of joining resin members to each other, there are a method using an adhesive, a method of mechanical joining, a method of hot plate welding, vibration welding, ultrasonic welding, heat welding, and the like, and recently, a method of manufacturing a laser welded body having advantages such as little influence on a resin member, a housed electronic component, and the like, and good workability has been attracting attention.

The laser welding is as follows: the laser beam is irradiated from the side of the transmitting side member to the joint surface of the transmitting side member, and the laser beam is scanned to melt the absorbing side member, thereby welding the two members.

However, thermoplastic polyester resins, particularly polybutylene terephthalate resins, have lower laser transmissivity than polycarbonate resins, polystyrene resins, and the like, and therefore have poor laser weldability and tend to have insufficient weld strength.

Further, since the polybutylene terephthalate resin is a crystalline resin, a difference in level is likely to occur in members formed by molding the resin members due to warping deformation, and a gap is likely to occur in the joint surfaces between the resin members to be joined, and in this case, it is more difficult to obtain high weld strength. With the recent complication of product design, there has been a demand for welding a molded article having a complicated shape without an axis of symmetry, such as a shape in which a joint surface is not circular, with a laser beam.

In order to improve the laser weldability of polybutylene terephthalate resins, a method of blending polybutylene naphthalate (PBN) and polyethylene naphthalate (PEN) has been proposed (patent document 1). However, this method is not sufficient for improving the welding strength of the members having the gaps at the joint surfaces. Further, a method of providing a ridge at the absorption side member and irradiating a laser beam with both resin materials in a pressurized state with a jig or the like has been proposed, and various ridge shapes have been proposed (patent document 2). However, although providing the ribs, and adopting various rib shapes and pressing are effective methods, a combination of a transmissive material and an absorptive material, or a complex shape without a symmetry axis cannot fill the gaps and is difficult to weld stably. Patent document 3 proposes a method of providing a projection on the joint surface of the transmission-side member, forming the projection into a polygonal shape, and applying pressure, but it is difficult to obtain stable welding strength only with the combination of the transmission material and the absorption material described in the complicated shape without the axis of symmetry. Further, there is a problem that the product is deformed when the pressure is excessively applied to fill the gap.

Documents of the prior art

Patent document

Patent document 1 Japanese patent No. 3510817

Patent document 2 Japanese laid-open patent publication No. 2005-288934

Patent document 3 Japanese patent laid-open publication No. 2011-

Disclosure of Invention

Problems to be solved by the invention

In view of the above circumstances, an object (problem) of the present invention is to provide a method for manufacturing a laser welded body in which members having welding joint surfaces of complicated shapes are laser welded at a stable high welding strength.

Means for solving the problems

The present inventors have made extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by forming a transmitting side member from a thermoplastic polyester resin containing a coloring material capable of transmitting and absorbing a laser beam (hereinafter referred to as a "laser beam transmitting and absorbing coloring material") and forming an absorbing side member from a thermoplastic polyester resin containing a coloring material capable of absorbing a laser beam and not transmitting a laser beam (hereinafter referred to as a "laser beam absorbing coloring material"), and performing laser welding while applying a thrust per unit distance of 10N/mm or less between the transmitting side member and the absorbing side member without having a symmetry axis at the joint surface therebetween, thereby completing the present invention.

The present invention relates to the following method for manufacturing a laser welded body.

[1] A method for manufacturing a laser welded body, characterized in that a transmission-side member for transmitting at least a part of a laser beam and an absorption-side member for absorbing the laser beam are laser welded with a joint surface interposed therebetween, the joint surface having a shape without a symmetry axis,

the transmitting side member is formed of a composition containing a laser beam transmitting and absorbing coloring material in a thermoplastic polyester resin, the absorbing side member is formed of a composition containing a thermoplastic polyester resin and a laser beam absorbing coloring material,

in the method for manufacturing the laser welded body, welding is performed while applying a thrust per unit distance of 10N/mm or less between the two members.

[2] The method of producing a laser welded body according to the above [1], wherein a height difference between a bonding surface of the absorption-side member and the transmission-side member, which is not pressed, is 0.01mm or more.

[3] The method of manufacturing a laser welded body according to the above [1] or [2], wherein a convex portion is formed on the joining surface of the absorption-side member.

[4] The method of manufacturing a laser welded body according to any one of the above [1] to [3], wherein a spot diameter of the laser beam is 1.5 to 3.0 mm.

[5] The method of manufacturing a laser welded body according to any one of the above [1] to [4], wherein a contour of a joint surface of the absorption-side member, which is in contact with the transmission-side member, is formed of 2 or more lines selected from a plurality of curves and straight lines having different curvatures.

[6] The method of manufacturing a laser welded structure according to any one of the above [1] to [5], wherein the power of the laser, the welding planned route, the scanning speed, and/or the scanning method are changed according to the shape of the joining surface of the absorbing-side member.

[7] The method for producing a laser welded structure according to any one of the above [3] to [6], wherein a decrease in height of the projection provided on the joining surface of the absorbing-side member before and after welding is 0.06 to 0.6 mm.

[8] The method of manufacturing a laser welded body according to any one of the above [1] to [7], wherein the laser beam transmittances of the joining portions of the transmitting-side members are partially different and continuously change.

[9] The method of manufacturing a laser welded body according to any one of the above [1] to [8], wherein a spot diameter of the laser beam is selected according to a shape, a width, and a height of the convex portion provided on the joining surface of the absorption-side member.

[10] The method for producing a laser welded structure according to any one of the above [1] to [9], wherein the laser beam transmitting and absorbing coloring material is Niger black.

[11] The method for producing a laser welded structure according to any one of the above [1] to [10], wherein the laser beam absorbing coloring material is carbon black.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the method for manufacturing a laser welded body of the present invention, laser welding can be performed with a stable high welding strength even for a member having a complicated joint surface.

Drawings

Fig. 1 is a schematic view showing an example of the method for producing a laser welded structure according to the present invention.

Fig. 2 is a view showing the shape of a convex portion (convex line) provided on the joint surface of the absorbent-side member used in the embodiment.

Fig. 3 is a diagram showing the shapes of the transmission-side member and the absorption-side member used in reference example 1.

Detailed Description

The method for manufacturing a laser welded body according to the present invention is a method for manufacturing a laser welded body in which a transmission-side member that transmits at least part of a laser beam and an absorption-side member that absorbs the laser beam are welded by laser with a joint surface interposed therebetween, the joint surface having a shape that does not have a symmetry axis,

the manufacturing method performs welding while applying a thrust per unit distance of 10N/mm or less between both members.

The present invention will be described in detail below. The following description is sometimes made based on representative embodiments and specific examples of the present invention, but the present invention is not 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 comprise a molded body of a thermoplastic polyester resin (a).

As the thermoplastic polyester resin (a), any of the following is preferable: (A1) a polybutylene terephthalate homopolymer, (a2) a polybutylene terephthalate copolymer resin, (A3) a homopolypbt-series mixed resin containing a polybutylene terephthalate homopolymer, or (a4) a copolymeric PBT-series mixed resin containing a polybutylene terephthalate copolymer resin.

(A1) polybutylene terephthalate homopolymer

A polybutylene terephthalate homopolymer (also referred to as "homopolypbt") is a polymer having a structure in which a terephthalic acid unit and a1, 4-butanediol unit are bonded to each other by an ester bond, and is a polymer containing a terephthalic acid unit and a1, 4-butanediol unit.

The terminal carboxyl group amount of the homopolymeric PBT is preferably 60 eq/ton or less, more preferably 50 eq/ton or less, and still more preferably 30 eq/ton or less.

The amount of terminal carboxyl groups of the polybutylene terephthalate homopolymer can be determined as follows: the resin was dissolved in 25mL of benzyl alcohol (0.5 g), and the solution was titrated with a 0.01 mol/l solution of sodium hydroxide in benzyl alcohol.

The amount of the terminal carboxyl group can be adjusted by any conventionally known method such as a method of adjusting the polymerization conditions such as the charging ratio of raw materials, the polymerization temperature, and the method of reducing the pressure during polymerization, and a method of reacting an end-capping agent.

The intrinsic viscosity of the homopolyPBT is preferably 0.5 to 2.0 dl/g. If the intrinsic viscosity is 0.5dl/g or more, the mechanical strength of the welded body is not excessively lowered, and if it is 2.0dl/g or less, it is possible to prevent the fluidity from being lowered to deteriorate the moldability or to lower the laser weldability.

From the above viewpoint, the intrinsic viscosity of the homopolyPBT is preferably 0.5 to 2dl/g, more preferably 0.6dl/g or more or 1.5dl/g or less, particularly preferably 0.7dl/g or more or 1.2dl/g or less.

The intrinsic viscosity is 1: 1 (mass ratio) in the mixed solvent at 30 ℃.

(A2) polybutylene terephthalate copolymer resin

The polybutylene terephthalate copolymer resin (also referred to as "copolymerized PBT") is a polybutylene terephthalate copolymer containing other copolymerized components than terephthalic acid units and 1, 4-butanediol units.

Examples of dicarboxylic acid units other than terephthalic acid include: aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 1, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, biphenyl-2, 2 ' -dicarboxylic acid, biphenyl-3, 3 ' -dicarboxylic acid, biphenyl-4, 4 ' -dicarboxylic acid, bis (4,4 ' -carboxyphenyl) methane, anthracenedicarboxylic acid, and 4,4 ' -diphenyletherdicarboxylic acid; 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.

Examples of the diol unit other than 1, 4-butanediol include aliphatic or alicyclic diols having 2 to 20 carbon atoms, bisphenol derivatives, and the like. Specific examples thereof include ethylene glycol, propylene glycol, 1, 5-pentanediol, 1, 6-hexanediol, neopentyl glycol, decanediol, cyclohexanedimethanol, 4 '-dicyclohexylhydroxymethane, 4' -dicyclohexylhydroxypropane, and ethylene oxide adduct diol of bisphenol A.

In the copolymerized PBT, the ratio of terephthalic acid in the dicarboxylic acid units is preferably 70 mol% or more, and more preferably 90 mol% or more, from the viewpoint of mechanical properties and heat resistance.

The ratio of 1, 4-butanediol in the diol unit is preferably 70 mol% or more, and more preferably 90 mol% or more.

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

The copolymerized PBT is particularly preferably a polybutylene terephthalate resin obtained by copolymerizing polyalkylene glycols (particularly polybutylene glycol (PTMG)) as a copolymerization component, or a dimer acid-copolymerized polybutylene terephthalate resin, and particularly preferably an isophthalic acid-copolymerized polybutylene terephthalate resin.

In the copolymerized PBT obtained by copolymerizing polytetramethylene glycol (PTMG), the ratio of the butylene glycol component in the copolymer is preferably 3 to 40 mass%, more preferably 5 mass% or more or 30 mass% or less, and particularly preferably 10 mass% or more or 25 mass% or less. Such a copolymerization ratio tends to result in excellent balance between laser weldability and heat resistance, and is preferable.

On the other hand, in the case of the 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% in terms of carboxylic acid groups, more preferably 1 mol% or more or 20 mol% or less, and particularly preferably 3 mol% or more or 15 mol% or less. Such a copolymerization ratio tends to be excellent in balance among laser weldability, long-term heat resistance, and toughness, and is preferable.

In the case of the copolymerized PBT obtained by copolymerizing isophthalic acid, the ratio of the isophthalic acid component to the total carboxylic acid component is preferably 1 to 30 mol% based on the carboxylic acid groups, more preferably 2 mol% or more or 20 mol% or less, and particularly preferably 3 mol% or more or 15 mol% or less. Such a copolymerization ratio tends to be excellent in balance among laser weldability, heat resistance, injection moldability and toughness, and is preferable.

As the PBT copolymer, in particular, PBT copolymer obtained by copolymerizing polytetramethylene glycol or PBT copolymer obtained by copolymerizing isophthalic acid is preferable from the viewpoint of laser weldability and moldability.

The intrinsic viscosity of the copolymerized PBT is preferably 0.5 to 2.0 dl/g. If the intrinsic viscosity is 0.5dl/g or more, the mechanical strength of the welded body is not excessively lowered, and if it is 2.0dl/g or less, it is possible to prevent the fluidity from being lowered to deteriorate the moldability or to lower the laser weldability.

From the above viewpoint, the intrinsic viscosity of the copolymerized PBT is preferably 0.5 to 2.0dl/g, more preferably 0.6dl/g or more and 1.5dl/g or less, and particularly preferably 0.7dl/g or more and 1.2dl/g or less.

The intrinsic viscosity is 1: 1 (mass ratio) in the mixed solvent at 30 ℃.

The amount of the terminal carboxyl group in the copolymerized PBT is preferably 60 eq/ton or less. When the amount of the terminal carboxyl group is 60 eq/ton or less, the generation of gas can be suppressed at the time of melt molding of the resin composition.

From the above-mentioned viewpoints, the amount of the terminal carboxyl group in the copolymerized PBT is preferably 60 eq/ton or less, more preferably 50 eq/ton or less, particularly preferably 30 eq/ton or less.

On the other hand, the lower limit of the amount of the terminal carboxyl group is not particularly limited. Usually 5 eq/ton or more.

The amount of the terminal carboxyl group of the copolymerized PBT can be determined as follows: the resin was dissolved in 25mL of benzyl alcohol (0.5 g), and the solution was titrated with a 0.01 mol/l solution of sodium hydroxide in benzyl alcohol.

< (A3) homopolymeric PBT-series hybrid resin comprising a polybutylene terephthalate homopolymer

The homopolymeric PBT-series hybrid resin comprising a polybutylene terephthalate homopolymer (also referred to as "homopolymeric PBT-series hybrid resin") is preferably a resin composition comprising a polybutylene terephthalate homopolymer (A3-1) and at least one resin (A3-2) selected from the group consisting of a polybutylene terephthalate copolymer resin, a polyethylene terephthalate resin, a polycarbonate resin, and an aromatic vinyl-series resin.

(polybutylene terephthalate homopolymer (A3-1))

The polybutylene terephthalate homopolymer is the same as the polybutylene terephthalate homopolymer (A1).

(polybutylene terephthalate copolymer resin (A3-2-1))

The polybutylene terephthalate copolymer resin (A3-2-1) was the same as the polybutylene terephthalate copolymer resin (A2).

(polyethylene terephthalate resin (A3-2-2))

The polyethylene terephthalate resin (also referred to as "PET") is a resin having an oxyethylene oxypropylene terephthaloyl unit composed of terephthalic acid and ethylene glycol as a main constituent unit with respect to all the constituent repeating units.

The resin composition may further contain repeating units other than the oxyethylene oxypropylene terephthalamide units.

PET is produced from terephthalic acid or a lower alkyl ester thereof and ethylene glycol as main raw materials. Other acid components and/or other glycol components may also be used in combination as the raw material.

Examples of the acid component other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4 '-diphenylsulfonedicarboxylic acid, 4' -biphenyldicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 3-phenylenedioxydiacetic acid and their structural isomers, dicarboxylic acids such as malonic acid, succinic acid, adipic acid and their derivatives, and oxo acids such as p-hydroxybenzoic acid and diglycolic acid and their derivatives.

Examples of the diol component other than ethylene glycol include aliphatic diols such as 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, pentamethylene glycol, hexamethylene glycol, and neopentyl glycol, alicyclic diols such as cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol a and bisphenol S.

The PET may be one obtained by copolymerizing a branched component, for example, a trifunctional acid such as trimesic acid, trimellitic acid, or a tetrafunctional acid having an ester-forming ability such as pyromellitic acid, or a trifunctional or tetrafunctional alcohol having an ester-forming ability such as glycerin, trimethylolpropane, pentaerythritol, or the like, in an amount of preferably 1.0 mol% or less, more preferably 0.5 mol% or less, and still more preferably 0.3 mol% or less.

The intrinsic viscosity of PET is preferably 0.3 to 1.5dl/g, more preferably 0.4dl/g or more or 1.2dl/g or less, particularly preferably 0.5dl/g or more or 0.8dl/g or less.

The intrinsic viscosity of the polyethylene terephthalate resin was measured in a ratio of 1: 1 (mass ratio) in the mixed solvent at 30 ℃.

The amount of terminal carboxyl group of PET is preferably 3 to 60 eq/ton. When the amount of the terminal carboxyl group is 60 eq/ton or less, gas is less likely to be generated during melt molding of the resin material, and mechanical properties of the obtained member for laser welding tend to be improved, and conversely, when the amount of the terminal carboxyl group is 3 eq/ton or more, heat resistance, heat retention stability, and hue of the member for laser welding tend to be improved, and this is preferable.

From the above viewpoint, the amount of the terminal carboxyl group of PET is preferably 3 to 60 eq/ton, more preferably 5 eq/ton or more or 50 eq/ton or less, and particularly preferably 8 eq/ton or more or 40 eq/ton.

The amount of terminal carboxyl groups in the polyethylene terephthalate resin was determined as follows: the amount of the polyethylene terephthalate resin was determined by dissolving 0.5g of the polyethylene terephthalate resin in 25mL of benzyl alcohol and titrating the solution with 0.01 mol/L of sodium hydroxide in benzyl alcohol.

The method for adjusting the terminal carboxyl group can be carried out by any conventionally known method such as a method of adjusting the polymerization conditions such as the charging ratio of raw materials, the polymerization temperature, and the method of reducing the pressure during the polymerization, and a method of reacting an end-capping agent.

(polycarbonate resin (A3-2-2))

The above polycarbonate resin (also referred to as "PC") is an optionally branched thermoplastic polymer or copolymer obtained by reacting a dihydroxy compound or a dihydroxy compound with a small amount of a polyhydroxy compound and phosgene or a carbonic diester.

The method for producing PC is not particularly limited, and polycarbonate resins produced by a melt polymerization method are preferably used from the viewpoint of laser beam transmittance and laser weldability, and those produced by a conventionally known phosgene method (interfacial polymerization method) and melt method (transesterification method) can be used.

The dihydroxy compound as the raw material is preferably an aromatic dihydroxy compound, and examples thereof include 2, 2-bis (4-hydroxyphenyl) propane (i.e., bisphenol a), tetramethylbisphenol a, bis (4-hydroxyphenyl) -p-diisopropylbenzene, hydroquinone, resorcinol, and 4, 4-dihydroxybiphenyl, and bisphenol a is preferably used. Further, a compound in which 1 or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound can also be used.

Of the above, as PC, an aromatic polycarbonate resin derived from 2, 2-bis (4-hydroxyphenyl) propane or an aromatic polycarbonate copolymer derived from 2, 2-bis (4-hydroxyphenyl) propane and another aromatic dihydroxy compound is preferable. Further, the polymer may be a copolymer such as a copolymer with a polymer or oligomer having a siloxane structure. Further, two or more of the above polycarbonate resins may be mixed and used.

The viscosity average molecular weight of the PC is preferably 5000-30000. When PC having a viscosity average molecular weight of 5000 or more is used, the mechanical strength of the resultant welded article can be maintained, and when it is 30000 or less, the deterioration of the flowability and the moldability of the resin composition, and the deterioration of the laser weldability can be suppressed.

From the above viewpoint, the viscosity average molecular weight of PC is preferably 5000 to 30000, more preferably 10000 or more or 28000 or less, particularly 14000 or more or 24000 or less.

The viscosity average molecular weight of PC is a viscosity average molecular weight [ Mv ] converted from the solution viscosity measured at a temperature of 25 ℃ using methylene chloride as a solvent.

The ratio (Mw/Mn) of the mass average molecular weight Mw to the number average molecular weight Mn of PC in terms of polystyrene as measured by Gel Permeation Chromatography (GPC) is preferably 2 to 5, more preferably 2.5 or more and 4 or less. If the Mw/Mn is excessively small, the fluidity in the molten state tends to be increased, and the moldability tends to be lowered. On the other hand, if the Mw/Mn is too large, the melt viscosity tends to increase, and molding tends to become difficult.

The amount of the terminal hydroxyl group of PC is preferably 100 mass ppm or more, more preferably 120 mass ppm or more, further preferably 150 mass ppm or more, and most preferably 200 mass ppm or more, from the viewpoints of thermal stability, hydrolytic stability, color tone, and the like. Among them, the content is usually 1500 mass ppm or less, preferably 1300 mass ppm or less, more preferably 1200 mass ppm or less, and most preferably 1000 mass ppm or less. When the amount of terminal hydroxyl groups in the polycarbonate resin is excessively small, the laser transmissivity tends to be reduced, and the initial color at the time of molding may be deteriorated. When the amount of terminal hydroxyl groups is too large, the heat retention stability and the moist heat resistance tend to be lowered.

(aromatic vinyl resin (A3-2-3))

The aromatic vinyl resin is a polymer mainly composed of an aromatic vinyl compound, and examples of the aromatic vinyl compound include styrene, α -methylstyrene, p-methylstyrene, vinyltoluene, and vinylxylene.

Further, as the aromatic vinyl resin, a copolymer obtained by copolymerizing an aromatic vinyl compound with another monomer may be used. As representative examples, there may be mentioned, for example: an acrylonitrile-styrene copolymer (AS resin) obtained by copolymerizing styrene and acrylonitrile, and a maleic anhydride-styrene copolymer (maleic anhydride-modified polystyrene resin) obtained by copolymerizing styrene and maleic anhydride.

Typical examples of the aromatic vinyl resin include Polystyrene (PS), acrylonitrile-styrene (AS), methyl methacrylate-styrene (MS), and styrene-maleic acid copolymer.

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

Examples of the rubber component copolymerized aromatic vinyl resin include rubber-modified polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylic rubber copolymer, methyl methacrylate-butadiene-styrene (MBS), acrylonitrile-styrene-acrylic (ASA), styrene-butadiene copolymer (SBS), and hydrogenated products thereof (SEBS), styrene-isoprene copolymer (SIS), and hydrogenated products thereof (SEPS).

Examples of the other copolymerizable monomer include α -unsaturated carboxylic acids such as acrylic acid and methacrylic acid, α -unsaturated carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, t-butyl methacrylate and cyclohexyl methacrylate, α -unsaturated dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, and imide compounds of α -unsaturated dicarboxylic acids such as N-phenylmaleimide, N-methylmaleimide and N-t-butylmaleimide.

The aromatic vinyl resin preferably has a mass average molecular weight of 50000 to 500000 as measured by GPC. When the molecular weight is 50000 or more, bleeding out can be suppressed, and lowering of weld strength due to generation of decomposition gas during molding can be suppressed. On the other hand, if the molecular weight is 500000 or less, the fluidity and the laser welding strength can be improved. From the above viewpoint, the aromatic vinyl resin preferably has a mass average molecular weight of 50000 to 500000 as measured by GPC, more preferably 100000 or more or 400000 or less, particularly 150000 or more or 300000.

When the aromatic vinyl resin is an acrylonitrile-styrene copolymer, the Melt Flow Rate (MFR) measured at 220 ℃ and 98N is preferably 0.1 to 50g/10 min. When the MFR is 0.1g/10 min or more, the compatibility with the polybutylene terephthalate resin is good, and appearance defects such as layer separation at the time of injection molding can be suppressed. On the other hand, if the MFR is 50g/10 min or less, the decrease in impact resistance can be suppressed. From the above-mentioned viewpoint, the Melt Flow Rate (MFR) of the aromatic vinyl resin is preferably 0.1 to 50g/10 min, more preferably 0.5g/10 min or more or 30g/10 min or less, particularly 1g/10 min or more or 20g/10 min or less.

When the aromatic vinyl resin is polystyrene, the MFR measured at 200 ℃ and 48N is preferably 1 to 50g/10 min, more preferably 3g/10 min or more or 35g/10 min or less, particularly preferably 5g/10 min or more or 20g/10 min or less.

When the aromatic vinyl resin is a butadiene rubber-containing polystyrene, the MFR measured at 200 ℃ and 49N is preferably 0.1 to 40g/10 min, more preferably 0.5g/10 min or more or 30g/10 min or less, particularly 0.8g/10 min or more or 20g/10 min or less.

(homopolyPBT and copolymeric PBT)

(A3) When the homopolypbt-series hybrid resin contains the homopolypbt and the copolymeric PBT, the content of the copolymeric PBT is preferably 10 to 90 mass% of 100 mass% of the total of the homopolypbt and the copolymeric PBT.

The content of the copolymerized PBT is preferably 90 mass% or less because moldability is improved because laser weldability is improved when the content is 10 mass% or more. From the above viewpoint, the content ratio of the copolymerized PBT is preferably 10 to 90 mass%, more preferably 15 mass% or more or 85 mass% or less, and particularly preferably 20 mass% or more or 80 mass% or less, with respect to 100 mass% of the total of the homopolypbt and the copolymerized PBT.

(homopolyPBT + PET)

(A3) When the homopolyPBT-series hybrid resin contains homopolyPBT and PET, the content of PET is preferably 5 to 50% by mass based on 100% by mass of the total of the homopolyPBT and the PET. The content ratio of PET is preferably 5% by mass or more because laser welding performance is high, and preferably 50% by mass or less because moldability is good. From the above viewpoint, the content of PET is preferably 5 to 50% by mass, more preferably 10% by mass or more or 45% by mass or less, and particularly preferably 15% by mass or more or 40% by mass or less, based on 100% by mass of the total of the homopolypbt and the PET.

(homopolyPBT + PC)

(A3) When the homopolyPBT-series hybrid resin contains homopolyPBT and PC, the content of PC is preferably 5 to 50% by mass based on 100% by mass of the total of the homopolyPBT and the PC. The content of PC is preferably 5% by mass or more because laser welding performance is high, and preferably 50% by mass or less because moldability is good. From the above viewpoint, the content of PC is preferably 5 to 50 mass%, more preferably 10 mass% or more or 45 mass% or less, and particularly preferably 15 mass% or more or 40 mass% or less, based on 100 mass% of the total of the homopolypbt and the PC.

(homopolyPBT + aromatic vinyl resin)

(A3) When the homopolypbt-series mixed resin contains the homopolypbt and the aromatic vinyl-series resin, the content ratio of the aromatic vinyl-series resin is preferably 5 to 50% by mass of 100% by mass of the total of the homopolypbt and the aromatic vinyl-series resin. The content ratio of the aromatic vinyl resin is preferably 5% by mass or more because the laser weldability is high, and preferably 50% by mass or less because the moldability is good. From the above viewpoint, the content ratio of the aromatic vinyl resin is preferably 5 to 50% by mass, more preferably 10% by mass or more or 45% by mass or less, and particularly preferably 15% by mass or more or 40% by mass or less, based on 100% by mass of the total of the homopolypbt and the aromatic vinyl resin.

The above describes a preferable content ratio in the case of combining the homopolyPBT (A3-1) with one of the homopolyPBT, PET, PC, and the aromatic vinyl resin (A3-2). Among them, a plurality of kinds can be suitably selected and used from the above (A3-2), and the content ratio of each of these is preferably 50% by mass or more of the homopolyPBT and/or the copolymeric PBT as a whole, and the total content of the above (A3-2) is preferably not more than 100% by mass in each ratio range.

For example, when an aromatic vinyl resin and PC are used in combination as (A3-2), it is preferable that the homopolyPBT is 50 mass% or more, the aromatic vinyl resin is 5 to 50 mass%, and the PC is 5 to 50 mass% and the total is 100 mass%.

When a plurality of the compounds (A4-2) are used in (A4) described later, the compounds can be combined in the same manner as described above.

< (A4) copolymerized PBT Mixed resin comprising a polybutylene terephthalate copolymerized resin

The copolymerized PBT-series hybrid resin comprising a polybutylene terephthalate copolymerized resin (hereinafter also referred to as "copolymerized PBT-series hybrid resin") is preferably a resin composition comprising copolymerized PBT (A4-1) and at least one resin (A4-2) selected from the group consisting of PET, PC and aromatic vinyl-series resins.

In this case, the copolymerized PBT (A4-1) in the copolymerized PBT-series hybrid resin (A4) was the same as the copolymerized PBT in the homopolymeric PBT-series hybrid resin (A3).

The PET, PC, and aromatic vinyl resin in the copolymerized PBT-series hybrid resin (a4) were the same as those in the homopolymeric PBT-series hybrid resin (A3).

(copolymerization PBT + PET)

When the copolymerized PBT-series hybrid resin (a4) contains copolymerized PBT and PET, the content of PET is preferably 50 mass% or less out of 100 mass% of the total of the copolymerized PBT and PET. It is preferable that the content of PET is 50% by mass or less because moldability is excellent. From the above viewpoint, the content of PET is preferably 50% by mass or less, more preferably 5% by mass or more or 40% by mass or less, and particularly preferably 5% by mass or more or 30% by mass or less, based on 100% by mass of the total of the copolymerized PBT and PET.

(copolymerization PBT + PC)

When the copolymerized PBT-series hybrid resin (a4) contains copolymerized PBT and PC, the content of PC is preferably 50 mass% or less out of 100 mass% of the total of the copolymerized PBT and PC. A content ratio of PC (B3-2) of 50% by mass or less is preferable because moldability is excellent. From the above viewpoint, the content of PC is preferably 50 mass% or less, more preferably 5 mass% or more or 40 mass% or less, and particularly preferably 5 mass% or more or 30 mass% or less, based on 100 mass% of the total of the copolymerized PBT and PC.

(PBT + aromatic vinyl resin copolymer)

When the copolymerized PBT-series hybrid resin (a4) contains the copolymerized PBT and the aromatic vinyl-series resin, the content ratio of the aromatic vinyl-series resin is preferably 50 mass% or less out of 100 mass% of the total of the copolymerized PBT and the copolymerized PBT. The content ratio of the aromatic vinyl resin is preferably 50% by mass or less because moldability is excellent. From the above viewpoint, the content ratio of the aromatic vinyl resin is preferably 50% by mass or less, more preferably 5% by mass or more or 45% by mass or less, and particularly preferably 5% by mass or more or 40% by mass or less, based on 100% by mass of the total of the copolymerized PBT and the copolymerized PBT.

[ transmitting-side Member ]

The laser beam transmitting member on the transmitting side is a member formed of a resin composition containing a thermoplastic polyester resin (A) and a laser beam transmitting absorbing coloring material, and transmits at least a part of the laser beam and absorbs a part of the laser beam.

Examples of the laser beam transmitting and absorbing coloring material include: various organic dye pigments such as azine-based pigments including nigrosine and nigrosine, phthalocyanine-based pigments, naphthalocyanine-based pigments, porphyrin-based pigments, quaterrylene-triphenylene-based pigments, azo-methine-based pigments, anthraquinone-based pigments, squaric acid derivatives, iminium-based pigments, quinacridone-based pigments, dioxazine-based pigments, diketopyrrolopyrrole-based pigments, anthrapyridone-based pigments, isoindolinone-based pigments, indanthrone-based pigments, perinone-based pigments, perylene-based pigments, indigo-based pigments, thioindigo-based pigments, quinophthalone-based pigments, quinoline-based pigments, and triphenylmethane-based pigments. One of these may be selected and used, or two or more of these may be used in combination.

In the present invention, "dye pigment" refers to a dye or a pigment.

The laser beam transmitting and absorbing coloring material contained in the transmitting-side member is preferably a dye pigment (X) which mainly absorbs at the wavelength of the laser beam and a dye pigment (Y) which mainly transmits the laser beam among the above-mentioned dye pigments to improve the degree of blackness.

As the above-mentioned dye pigment (X) which mainly absorbs at the wavelength of the laser beam, a condensation mixture containing an Azine-based compound having an Azine (Azine) skeleton is preferable. As the condensation mixture of the azine-based compound having an azine skeleton, nigrosine is preferable. By containing nigrosine, the transmission-side member is also melted by heat radiation by the laser beam, and sufficient welding strength can be achieved even for a complicated shape that is difficult to weld properly when only the absorption-side member is melted by heat radiation.

Nigrosine is a mixture of Azine-based compounds having an Azine (Azine) skeleton, functions as a dye having laser beam absorbability, and has a moderate absorption in a laser beam range of 800nm to 1200 nm. Nilotin Black is a Black azine-based condensation mixture described as C.I. solvent Black 5 and C.I. solvent Black 7 in the Color Index.

Nile black can be synthesized, for example, as follows: aniline, aniline hydrochloride and nitrobenzene are subjected to oxidation and dehydration condensation at the reaction temperature of 160-190 ℃ in the presence of ferric chloride, so that the synthesis can be realized.

The content of the dye pigment (X) such as Niger black is preferably 0.001 to 0.6 part by mass based on 100 parts by mass of the thermoplastic polyester resin (A). When the content of the dye pigment (X) is 0.001 parts by mass or more, the dye pigment (X) is preferably uniformly dispersed and absorbs the laser beam, and the resin is uniformly melted. Further, if it 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, and therefore, it is preferable.

From the above viewpoint, the content of the dye pigment (X) is preferably 0.001 to 0.6 parts by mass, more preferably 0.02 parts by mass or more and 0.3 parts by mass or less, and particularly preferably 0.05 parts by mass or more and 0.1 parts by mass or less, based on 100 parts by mass of the thermoplastic polyester resin (a).

Examples of the dye pigment (Y) that mainly transmits a laser beam include anthraquinone dye pigments, perinone dye pigments, and azomethine dye pigments.

The color exhibited by these dye pigments depends on the absorption wavelength of light, and in order to improve the degree of blackness, specifically, there can be mentioned: a combination of a dye pigment exhibiting blue color (hereinafter also referred to as a blue dye) and a dye pigment exhibiting yellow color (hereinafter also referred to as a yellow dye) and a dye pigment exhibiting red color (hereinafter also referred to as a red dye); a combination of a dye pigment exhibiting violet color (hereinafter also referred to as violet dye) and a yellow dye; a combination of a dye pigment exhibiting green color (hereinafter also referred to as a green dye) and a dye pigment such as a red dye, a blue dye, and a dye pigment exhibiting brown color (hereinafter also referred to as a brown dye).

The preferred blue dye is an anthraquinone dye having a maximum absorption wavelength in the range of 590 to 635 nm. Anthraquinone dyes are typically blue oil soluble dyes. By combining the dye as the laser beam transmitting absorbing coloring material contained in the transmitting side member, for example, the visibility is higher than that of a green anthraquinone dye, and even when a black mixed dye is combined, a red dye and a yellow dye can be combined by subtractive color mixing, thereby obtaining a coloring agent having high coloring power and expressing black.

As the anthraquinone dye having a maximum absorption wavelength of 590 to 635nm, one having a thermogravimetric analyzer TG/DTA measurement value (decomposition initiation temperature) in the presence of air of 300 ℃ or higher is preferably selected.

Preferable anthraquinone dyes may be exemplified by c.i. solvent blue 97 (decomposition start temperature 320 ℃) described in COLOR INDEX, c.i. solvent blue 104 (decomposition start temperature 320 ℃) and the like. These may be used singly or in combination. However, if the amount of the compound is increased, bleeding from the molded article tends to occur in a high-temperature atmosphere, and the thermal discoloration resistance tends to deteriorate.

Examples of the commercially available anthraquinone dyes include "NUBIAN (registered trademark) BLUE series" and "opas (registered trademark) BLUE series" (both trade names, Orient Chemical Industries co., ltd.).

As a preferable red dye, a perinone dye having excellent heat resistance can be selected, and a red perinone dye having a maximum absorption wavelength in the range of 460 to 480nm can be mentioned. Specific examples of such a perinone dye include c.i. solvent red 135, 162, 178, 179, and the like. These may be used singly or in combination. However, if the amount of the compound is increased, bleeding from the molded article tends to occur in a high-temperature atmosphere, and the thermal discoloration resistance tends to deteriorate.

Examples of commercially available RED perinone dyes include "NUBIAN (registered trademark) RED series" and "OPLAS (registered trademark) RED series" (both trade names, Orient Chemical Industries co., ltd.) and the like.

As a preferred yellow dye, an anthraquinone dye having good heat resistance can be selected, and an anthraquinone dye having a maximum absorption wavelength in the range of 435 to 455nm is suitable. Anthraquinone dyes with a maximum absorption wavelength in the range of 435-455 nm are typically yellow oil-soluble dyes.

Specific examples of the yellow anthraquinone dye include c.i. solvent yellow 163, c.i. vat yellow 1,2, and 3. These may be used singly or in combination. These may be used singly or in combination. However, if the amount of the compound is increased, bleeding from the molded article tends to occur in a high-temperature atmosphere, and the thermal discoloration resistance tends to deteriorate.

Examples of commercially available YELLOW anthraquinone dyes include "NUBIAN (registered trademark) YELLOW series" and OPLAS (registered trademark) YELLOW series "(trade name, Orient Chemical Industries Co., Ltd.).

As a preferred brown dye, azomethine dyes can be selected. Examples thereof include a composition containing at least 1 represented by the following formula (1): a dye of type 1 azomethine nickel complex.

[ in the formula (1), R¹～R⁸The same or different from each other, hydrogen atom, alkyl group having 1 to 18 carbon atoms, alkoxy group having 1 to 18 carbon atoms, carboxyl group, hydroxyl group, amino group, alkylamino group, nitro group or halogen atom.]

As R in formula (1)¹～R⁸The alkyl group having 1 to 18 carbon atoms in (b) preferably includes, for example, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a neopentyl group, an isopentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a 2-ethylhexyl group, a n-decyl group, etc., the alkoxy group having 1 to 18 carbon atoms preferably includes, for example, a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a n-pentoxy group, a neopentoxy group, a n-hexoxy group, a n-heptoxy group, a n-octo.

1: the azomethine dye used for the type 1 azomethine nickel complex can be produced by a known method. For example, the compound can be obtained by reacting diaminomaleonitrile represented by the following reaction formula with salicylaldehyde optionally having a substituent.

[ solution 2]

In the formula (2), R¹～R⁸The same as in the above formula (1).

By metallizing the azomethine dye with a nicking agent, such as nickel acetate, 1: type 1 azomethine nickel complex.

[ solution 3]

In the formula (3), R¹～R⁸The same as in the above formula (1).

The resulting nickel complex is a stable complex in which azomethine dye acts as a chelating 4-dentate ligand.

1: the type 1 azomethine nickel complex is excellent in soundness such as heat resistance and light resistance, and therefore is useful as a resin composition for outdoor members or members exposed to heat, is less likely to undergo thermal change during melting during laser welding, and is suitable as a colorant for laser-welded members.

1 represented by the above formula (1): specific examples of the type 1 azomethine nickel complex include R¹～R⁸Examples of the compounds are shown in the following Table 1, examples 1 to 7, and the like.

The azomethine nickel complex used as the laser beam transmitting/absorbing coloring material contained in the transmitting member is not limited to these

[ Table 1]

When the transmitting member contains a dye pigment (Y) mainly transmitting the laser beam, which is used as the laser beam transmitting/absorbing colorant, it is preferable to use an anthraquinone dye pigment (C1) having a maximum absorption wavelength of 590 to 635nm, a perinone dye pigment (C2) having a maximum absorption wavelength of 460 to 480nm, and an anthraquinone dye pigment (C3) having a maximum absorption wavelength of 435 to 455 nm.

Since the hues of the dye pigment (X) which is a dye pigment mainly absorbing at the wavelength of a laser beam and the hue of the dye pigment (Y) which is a dye pigment mainly transmitting a laser beam vary depending on the compatibility with the thermoplastic polyester resin (a), it is desirable to adjust the ratio of each dye constituting the dye pigment (Y) so as to obtain a molded plate of jet black suitable as a black hue. In this case, the content ratio of C1 to C3 is preferably C1: c2: c3 is 24-42: 24-48: 22 to 46. Further preferred is C1: c2: the ratio of C3 is 24-41: 24-39: 22 to 46.

The laser beam transmitting dye pigment (Y) mainly transmitting the laser beam used as the laser beam transmitting/absorbing coloring material contained in the transmitting side member is preferably a coloring agent containing a perinone dye pigment (C2) having a maximum absorption wavelength in the range of 460 to 480nm and an anthraquinone dye pigment (C1) having a maximum absorption wavelength in the range of 590 to 635nm, and the mass ratio of the two is C2/C1 in the range of 0.4 to 2. In view of color development and bleeding inhibition by the resin composition used in the present invention, the amount is more preferably 0.4 to 1.5, and still more preferably 0.6 to 1.5.

Examples of the other dye pigments which can be used in combination include azo-based, quinacridone-based, dioxazine-based, quinophthalone-based, perylene-based, perinone-based (compounds having a wavelength different from that of C2), isoindolinone-based, triphenylmethane-based, anthraquinone-based (compounds having a wavelength different from that of C1 or C3), azomethine-based dye pigments, and the like. Among them, nickel is preferably not contained.

The content of the laser beam transmitting/absorbing coloring material is preferably 0.0005 to 5.0 parts by mass per 100 parts by mass of the polyester resin material (A). When the content of the transparent and absorptive coloring material is 0.0005 parts by mass or more, the resin absorbs the laser beam and melts, and therefore, it is preferable. On the other hand, if the content is 5.0 parts by mass or less, bleeding of the dye and pigment can be suppressed, and the amount of heat generation can be controlled, which is preferable.

From the above viewpoint, the content of the laser beam transmitting/absorbing coloring material is preferably 0.0005 to 5.0 parts by mass, more preferably 0.001 part by mass or more and 4.0 parts by mass or less, particularly preferably 0.005 part by mass or more and 3.0 parts by mass or less, per 100 parts by mass of the polyester resin (a).

As described above, in the case of combining the dye pigment (X) for main absorption at the wavelength of the laser beam and the dye pigment (Y) for main transmission of the laser beam as the laser beam transmitting absorption coloring material, the dye pigment (X) is preferably 0.0005 to 0.6 parts by mass with respect to 100 parts by mass of the polyester-based resin (A).

When the content of the dye pigment (X) is 0.0005 parts by mass or more, the dye pigment is preferably uniformly dispersed, and the resin is preferably uniformly melted by absorbing the laser beam. 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, and therefore, it is preferable.

From the above viewpoint, the content of the dye pigment (X) is preferably 0.0005 to 0.6 parts by mass, more preferably 0.001 parts by mass or more or 0.3 parts by mass or less, particularly preferably 0.003 parts by mass or more or 0.1 parts by mass or less, based on 100 parts by mass of the polyester resin (a).

The dye pigment (Y) for transmitting mainly laser beam is preferably 0.0005 to 5 parts by mass with respect to 100 parts by mass of the polyester resin (A).

The content of the dye pigment (Y) for transmitting mainly laser beam is preferably 5.0 parts by mass or less because bleeding of the dye pigment is less likely to occur.

From the above viewpoint, the content of the dye pigment (Y) for transmitting mainly laser beam is preferably 0.0005 to 5 parts by mass, more preferably 0.05 part by mass or more or 4 parts by mass or less, particularly 0.1 part by mass or more or 3 parts by mass or less, based on 100 parts by mass of the polyester resin (a).

The ratio (Y/X) of the dye-pigment (Y) content to the dye-pigment (X) content is preferably 1 to 100, more preferably 10 or more or 90 or less, particularly 20 or more or 80 or less.

[ absorbent side Member ]

The absorption side member is formed of a resin composition containing a thermoplastic polyester resin (A) and a laser beam absorbing coloring material. Examples of the laser beam absorbing coloring material include black coloring agents such as carbon black, white coloring agents such as titanium oxide and zinc sulfide, and at least one of these may be used or two or more of these may be used in combination. Among them, carbon black is preferably contained.

As the carbon black, at least one of furnace black, thermal black, channel black, lamp black, acetylene black, and the like; or two or more of them may be used in combination.

For the carbon black, carbon black which is masterbatch-formed in advance with a resin component constituting the thermoplastic polyester resin (a) or another resin is also preferably used for easy dispersion.

From the viewpoint of dispersibility, the primary particle diameter of the carbon black is preferably from 10nm to 30nm, and more preferably from 15nm to 25 nm. When the dispersibility is good, welding unevenness at the time of laser welding is reduced.

Further, from the viewpoint of jet-blackness, the nitrogen adsorption specific surface area of the carbon black measured in JIS K6217 is preferably 30 to 400m²In terms of/g, 50m is more preferred²More than g, in particular 80m²More than g.

Further, from the viewpoint of dispersibility, the DBP absorption of the carbon black measured according to JIS K6221 is preferably 20 to 200cm³100g, more preferably 40 to 170cm³100g, more preferably 50 to 150cm³100g of the total weight. When the dispersibility is good, welding unevenness at the time of laser welding is reduced.

The content of the laser beam-absorbing coloring material is preferably 0.15 to 10 parts by mass per 100 parts by mass of the thermoplastic polyester resin (A). When the content of the laser beam absorbing coloring material is 0.15 parts by mass or more, the resin releases heat and melts upon laser irradiation, and when it is 10 parts by mass or less, the resin can be prevented from being decomposed by rapid and excessive heat release, which is preferable.

From the above viewpoint, the content of the laser beam absorbing coloring material is preferably 0.15 to 10 parts by mass, more preferably 0.15 to 5 parts by mass, and still more preferably 0.15 to 1 part by mass, based on 100 parts by mass of the polyester resin (a).

The absorbing-side member may suitably contain other components than the thermoplastic polyester resin (a) and the laser beam absorbing coloring material.

As other components, laser beam transmitting absorbing coloring materials such as Niger black can be cited. The absorbing member may or may not contain a laser beam transmitting absorbing coloring material such as nigrosine. By not containing a laser beam transmitting/absorbing coloring material, especially nigrosine, it is possible to prevent heat-resistant discoloration and light-resistant discoloration.

Nigrosine is as described above. The content of the absorbent member containing nigrosine is preferably 0.001 to 0.6 parts by mass per 100 parts by mass of the thermoplastic polyester resin (A). If the content of nigrosine is 0.001 parts by mass or more, nigrosine uniformly disperses and absorbs the laser beam and the resin uniformly melts, and therefore, it is preferable, and if it is 0.6 parts by mass or less, the laser beam is transmitted to such an extent that welding is possible, and foaming due to decomposition of the resin caused by excessive absorption of the laser beam can be suppressed, and therefore, it is preferable. The content of nigrosine is more preferably 0.02 to 0.3 part by mass, and still more preferably 0.05 to 0.1 part by mass.

[ other Components contained ]

The transmission-side member and the absorption-side member may contain various additives other than the above components as desired. Examples of such additives include reinforcing fillers, impact modifiers, flow modifiers, color promoters, dispersants, stabilizers, plasticizers, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, lubricants, mold release agents, crystallization promoters, crystallization nucleating agents, flame retardants, and epoxy compounds.

[ shape of Member ]

The shape of the member is arbitrary. For example, the plate-like shape may be a rectangular shape, or may be another complicated shape. For example, the molded article may be a profile extrusion (rod, tube, or the like) to be welded with the ends butted, or may be a molded article in which metal is embedded for use in a current-carrying member, an electronic component, or the like, which requires high water resistance and airtightness.

The method of molding the member is also arbitrary. Examples of the molding method include injection molding, ultrahigh-speed injection molding, injection compression molding, two-color molding, gas-assist or other hollow molding, molding using a heat-insulating mold, molding using a rapid-heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, and the like.

The transmission-side member needs to transmit the laser beam throughout its entire thickness, and therefore is not preferably excessively thick. On the other hand, if it is too thin, the strength of the molded article becomes weak, which is not preferable.

From the above viewpoint, the thickness of the joining portion of the transmission-side member to be laser-welded is preferably 0.2mm to 4.0mm, more preferably 0.4mm or more or 3.5mm or less, and particularly preferably 0.5mm or more or 3.0mm or less.

[ relationship between Transmission-side Member and absorption-side Member ]

From the viewpoint of bonding strength, the transmission-side member and the absorption-side member are further preferably: the difference between the melting point Tm-A and the crystallization temperature Tc-A of the transmission-side member ((Tm-A) - (Tc-A)) is larger than the difference between the melting point Tm-B and the crystallization temperature Tc-B of the absorption-side member ((Tm-B) - (Tc-B)). Particularly, the resin used in the absorbent-side member is strongly influenced, but ((Tm-A) - (Tc-A)) - ((Tm-B) - (Tc-B)) is preferably in the range of 0 to 30 ℃, more preferably in the range of 2 to 20 ℃, particularly preferably in the range of 3 to 15 ℃, particularly 4 to 10 ℃.

In order to satisfy the above, for example, the mixing ratio of the thermoplastic polyester resin (a) used in the absorption-side member, the selection of various additive materials and the adjustment of the amount of blending may be adjusted, the selection of the laser beam transmitting absorption dye pigment of the thermoplastic polyester resin (a) used in the transmission-side member and the adjustment of the amount of blending may be adjusted, and the like. But is not limited to these adjustment methods.

From the viewpoint of bonding strength, the melting enthalpy Δ Hm-a of the transmission-side member and the melting enthalpy Δ Hm-B of the absorption-side member are more preferably: the melting enthalpy of the transmitting side member Δ Hm-A is higher than the melting enthalpy of the thermoplastic polyester-based resin (A) used in the absorbing side member Δ Hm-B. (Δ Hm-A) - (Δ Hm-B) is preferably in the range of 0 to 20J/g, more preferably in the range of 0.5 to 10J/g, and particularly preferably in the range of 2 to 9J/g.

In order to satisfy the above, for example, the mixing ratio of the thermoplastic polyester resin (a) used in the absorption side member, the selection of various additive materials and the adjustment of the amount of blending may be adjusted, and the selection of the laser beam transmitting absorption dye pigment of the thermoplastic polyester resin (a) used in the transmission side member and the adjustment of the amount of blending may be adjusted. But is not limited to these adjustment methods.

The melting point Tm, the crystallization temperature Tc, and the melting enthalpy Δ Hm can be determined as follows: the measurement was carried out by cutting out a sample from a portion located at a distance of 5mm or more from the gate of the injection mold, of the transmission-side member and the absorption-side member molded by injection molding, and measuring the cut sample.

[ method for producing laser welded body ]

The method for producing the thermoplastic polyester resin (a) used for the transmission-side member and the absorption-side member may be a method in which a resin composition is produced by a conventional method and the resin composition is molded by a conventional method.

For example, the raw materials constituting the transmission-side member or the absorption-side member may be mixed and melt-kneaded by a single-screw extruder or a twin-screw extruder. Alternatively, the resin composition may be prepared by supplying the components to an extruder by a feeder without premixing the components or by premixing only a part of the components, and melt-kneading the components.

Further, a portion of the resin constituting the transmission-side member or the absorption-side member may be partially mixed with a portion of the other resin to prepare a master batch, and then the remaining resin and the other components may be mixed therewith to perform melt-kneading.

When a fibrous reinforcing filler such as glass fiber is used, it is also preferably supplied from a side feeder in the middle of the cylinder of the extruder.

The heating temperature in the melt kneading may be suitably selected from the range of 220 to 300 ℃. If the temperature is too high, decomposition gas is likely to be generated, which may cause the opacity. Therefore, it is desirable to select the screw configuration in consideration of shear heat release and the like. In order to suppress decomposition during kneading and molding in the subsequent step, it is desirable to use an antioxidant and a heat stabilizer.

The method of molding the transmission-side member and the absorption-side member may be any method.

Examples of the molding method include injection molding, ultrahigh-speed injection molding, injection compression molding, two-color molding, gas-assist or other hollow molding, molding using a heat-insulating mold, molding using a rapid-heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, and the like.

[ laser welding ]

In laser welding, a transmission-side member formed by molding the thermoplastic polyester resin material by injection molding or the like is brought into surface contact or point contact with an absorption-side member, and a laser beam is irradiated from the transmission-side member side to melt and integrate at least a part of an interface for joining the two members, thereby forming 1 molded article.

The shape of the transmission-side member and the absorption-side member is not limited as long as the shape of each member is a shape that can be joined by laser welding, and in the present invention, the transmission-side member and the absorption-side member can be welded even in a complicated shape, and therefore, when the joint surface of the transmission-side member and the absorption-side member is viewed from the transmission-side member, the shape of the joint surface does not have an axis of symmetry. With respect to the shape of the absorption-side member, it is particularly preferable that the welding planned line of the joint surface is constituted by 2 or more lines selected from the group consisting of a plurality of curved lines and straight lines having different curvatures when the joint surface is viewed from the transmission-side member.

The transmission-side member may have the same size and shape as the joining portion of the absorption-side member, may have a larger size and shape than the joining portion of the absorption-side member, or may have a different shape from the joining portion of the absorption-side member.

The method for manufacturing a laser welded body according to the present invention will be described below with reference to the drawings.

Fig. 1 is a schematic view showing an example of the method for producing a laser welded structure according to the present invention. For example, as shown in fig. 1, the absorption-side member 1 is formed of a box-shaped member, the upper surface 3 of which has a polygonal shape of a to f obtained by cutting out a part of a rectangle, and the transmission-side member 2 has a shape of a cover covering the absorption-side member 1 as shown in fig. 1, for example, and the lower surface of which is in surface contact with the joining surface 3 of the absorption-side member 1.

The joint surface 3 between the absorption-side member 1 and the transmission-side member 2 may be smooth or rough, or may have an intentionally convex projection or fitting structure. Particularly preferably, the joint surface is formed with a convex portion. The shape of the projection when provided is not particularly limited, and the vertical cross-sectional shape of the projection may be, for example, a mountain shape, a semicircle shape, a triangle shape, a quadrangle shape, a trapezoid shape, or the like, or a combination thereof. The width and height of the laser beam are arbitrary, and depend on the laser spot diameter and the desired shape of the fusion body.

The absorbing-side member is particularly preferably formed with a convex portion. In fig. 1, the convex portions 4 in which the convex portions are linearly connected are formed so as to surround the entire circumference of the periphery of the joint surface 3 of the absorbent-side member 1, and the convex portions may be arranged in parallel in 2 rows or 3 rows or more, or in parallel in 2 rows or 3 rows or more, and in a dot-like row in which the convex portions are continuous.

The difference in level of the joining surface is caused by various factors, for example, shrinkage and warpage due to primary shrinkage and secondary shrinkage (annealing, etc.) in molding, which are caused by a combination of factors such as the shape of the molded article and molding conditions. Further, the influence may affect the entire molded product or may affect a part such as a convex part. Although it is possible to achieve the purpose by optimizing the combination of the resin composition, molding conditions, annealing conditions, and the like, the height difference is desired to be reduced infinitely in order to obtain sufficient weld strength, the height difference may be allowed to exist to some extent or more because of the allowable range of the design of the molded product and the manufacturing cost. In the method of the present invention, sufficient welding strength can be achieved even with a height difference of 0.01mm or more.

The difference in height between the bonding surfaces is preferably 0.01 to 0.5mm, more preferably 0.02 to 0.4mm, and still more preferably 0.05 to 0.3mm or less.

The height difference of the joint surface is represented as: the difference between the highest position with respect to the reference plane and the lowest position with respect to the reference plane in the entire welding scheduled line. The level difference of the joining surface is continuously varied.

In addition, shrinkage and warpage may occur in either or both of the transmission-side member and the absorption-side member, and particularly, the step in the case of the member side where the convex portion is not provided means the distance from the reference surface to the joint surface. When both the concave portion and the convex portion are formed, they are expressed as a gap when the both members are overlapped without being pressurized, and they can be measured by using a dedicated inspection tool or simply using a combination of a feeler gauge, a dial gauge, a height gauge, a dial gauge, and the like.

In the measurement, the distance from the reference surface to the bonding surface or to the top surface of the convex portion is measured with 3 points of the transmission-side member and/or the absorption-side member as the reference surface.

The transmittance of the transmitting member is not particularly limited as long as at least a part of the laser beam can be transmitted, and the transmittance of 940nm having a wavelength of 1.5mm is preferably 5 to 99%, more preferably 15 to 80%, and further preferably 20 to 70%.

Regarding the transmittance, there is no large difference in transmittance if it is a test piece shape such as JIS standard, and if it is a practical product shape, a position where the transmittance is high and a position where the transmittance is low appear depending on a gate position of a molded product and a shape of the molded product, and the transmittance is not always completely uniform, and the laser beam transmittance of the joint portion of the transmission side member is usually partially different and continuously changes. When welding is performed at the same power and the same scanning speed with different transmittances, although variation in welding strength is likely to occur, the method of the present invention can obtain good welding strength even in a molded article in which the laser beam transmittance is partially different and continuously changes.

The type of laser beam to be irradiated for laser welding is not particularly limited, and may be selected from solid laser, fiber laser, semiconductor laser, gas laser, liquid laser, and the like. For example, YAG (yttrium aluminum garnet crystal) laser light (wavelength 1064nm, 1070nm), LD (laser diode) laser light (wavelength 808nm, 840nm, 940nm, 980nm), or the like can be preferably used. Particularly preferred are laser beams having wavelengths of 940nm, 980nm, 1070 nm. The excitation pattern may be either CW or pulsed. The irradiation method is also not particularly limited, and may be suitably selected from the following methods: the laser head is moved through the mechanical arm; a Galvo scanning mode in which a laser beam is reflected by a mirror and scanned; a method of providing a plurality of laser heads and irradiating the welded surface simultaneously.

The laser spot diameter is preferably 0.1mm or more and 30mm or less, more preferably 0.2mm or more and 10mm or less, still more preferably 0.3mm or more and 5mm or less, and particularly preferably 1.5 to 3.0 mm. If the amount is less than this, welding is likely to be difficult, and if it is more than this, it is difficult to control the welding width. In addition, the spot diameter of the laser beam is preferably selected according to the shape, width, and height of the convex portion.

The laser beam may be focused on the joining surface or defocused on the joining surface, and is appropriately selected according to the desired welded body.

The welding conditions are not particularly limited, and may be variously selected depending on the specifications of the apparatus, depending on the combination of the conditions such as the type of laser, the diameter of the laser, the laser power, the scanning speed, the members to be welded, and the shape of the members, and the like, and for example, the laser power is preferably 1 to 1000W, more preferably 10 to 500W, and further preferably 15 to 200W. If the power is higher than this, the cost of the laser welding equipment is excessively high, and if it is lower than this, it is likely to be difficult to obtain sufficient welding strength.

The laser scanning speed is preferably 0.1 to 20000mm/s, more preferably 1 to 10000mm/s, and still more preferably 10 to 1000 mm/s.

In addition, as the laser scanning method, it is more preferable to change the power of the laser, the welding planned route, the scanning speed, and/or the scanning method in accordance with the shape of the joint surface from the viewpoints of welding efficiency, welding strength, welding appearance, and device load.

When laser welding is performed, first, the transmission-side member 2 and the absorption-side member 1 are overlapped with the convex portion 4 of the joint surface 3, and the transmission-side member 2 and the absorption-side member 1 are maintained in an overlapped state. In the case of maintaining the stacked state, a transparent plate material such as a glass plate, a quartz plate, or an acrylic plate may be disposed on the transmission-side member 2, i.e., on the laser-irradiated side. In particular, when a glass plate or a quartz plate is disposed, it is preferable to promote the release of heat generated during laser welding and to obtain a good appearance.

Next, the laser beam X is scanned and irradiated from above the transmission-side member 2 on the planned welding line 5 corresponding to the projection 4 provided on the peripheral edge of the absorption-side member 1. At this time, almost all or most of the laser beam X is transmitted through the transmission-side member 2. The laser beam X is absorbed around the convex portion 4 of the absorption-side member 1, and the vicinity of the surface of the convex portion 4 releases heat and melts. In addition, a part of the laser beam X is absorbed and heat is released by the resin composition of the transmission-side member 2, contributing to welding. Further, at least at the time of laser welding and joining of the two members, a thrust per unit distance of 10N/mm or less, preferably 9N/mm or less, more preferably 5N/mm or less, and particularly preferably 3N/mm or less is applied to the two members by a jig or a pressing means. When the pressing is performed in the above manner, residual stress remains in the molded product, or the difference in level due to warp deformation tends to increase, and therefore smoke is generated or sufficient welding strength cannot be obtained. By doing so, the joining surface of the absorption-side member 1 and the transmission-side member are fused, and after the irradiation of the laser beam X is stopped, the fused portion of the transmission-side member 2 and the absorption-side member 1 is cooled and solidified, and both members are welded and integrated with high strength.

The thrust per unit distance is preferably 0.4N/mm or more. If the amount is less than this, adhesion of the joining surfaces cannot be ensured, and welding is difficult to achieve.

As described in the examples, the thrust per unit distance at the time of laser welding joining of the two members can be obtained by dividing the actual pressing pressure (N) by the circumferential length (mm) of the planned welding line.

The scanning of the laser beam X may be performed for 1 turn toward the convex portion 4 of the bonding surface 3 of the absorption-side member 1, or may be performed for 2 or more turns. When the scanning of the laser beam X deviates from the welding planned route (in fig. 1, the projection 4), smoke is generated and welding becomes difficult, and therefore, it is important to select the scanning position.

When the convex part is provided on the joint surface of the absorbing side member, the amount of reduction in height of the convex part before and after laser welding is preferably 0.06 to 0.6 mm. The amount of decrease (amount of change) in the height of the projection can be measured by digitizing the displacement caused by the melting of the projection during welding with a displacement meter.

In laser welding, since the total heat amount (J) described below greatly depends on the degree of welding, excellent weldability can be easily achieved by making the total heat amount (J) approximately the same using the total heat amount (J) as an index when various conditions are different.

Note that the total heat amount is calculated by the following equation.

Heat input (J/mm) power (W)/scanning speed (mm/s)

Total heat (J) × 1 turn of scan distance (mm) × number of turns (turn) × heat input (J/mm)

According to the method for manufacturing a laser welded body of the present invention, a welded body having high bonding strength can be obtained. The weld strength of the welded structure of the present invention is preferably 300N or more, more preferably 500N or more, particularly 750N or more, further 900N or more, further 1000N or more, and most preferably 1200N or more.

When laser welding is performed, the resin may be decomposed depending on conditions, and smoke may be generated due to various factors. This smoke is a gaseous substance formed by a resin decomposition product, and may be cooled and fixed to the welded body, thereby significantly impairing the appearance. Further, when electronic components and the like are incorporated in the welded body, the electronic components are also adversely affected, which is not preferable. Therefore, it is preferable that the weld strength is sufficient but not smoke.

Further, the power and scanning speed of the laser welding apparatus are limited by the structure thereof, and when welding is performed under conditions close to the upper limit, not only a welded body with stable bonding strength cannot be obtained and a defective product may be produced, but also the apparatus itself may be damaged, which is not preferable. Therefore, it is also important to consider these factors when determining weldability.

The shape, size, thickness, and the like of the welded body integrated by laser welding are arbitrary, and the welded body is particularly suitable for use as an electric component for transportation equipment such as an automobile, an electric/electronic component device component, an industrial machine component, other consumer components, and the like. Further, since the welding strength is high and as a result, the pressure-resistant strength is also high, it is also preferably used for applications requiring airtightness, such as a container for housing electric and electronic components such as an electronic board, a circuit, a sensor, a solenoid, a motor, a transformer, and a battery.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[ production of absorbent side Member A-C ]

The components shown in Table 2 below were mixed in amounts (parts by mass) shown in compositions A to C on the absorption side of Table 2, and the mixture was kneaded at 250 ℃ with a 30mm vented twin-screw extruder to obtain strands, thereby obtaining pellets of compositions A to C on the absorption side.

[ Table 2]

The obtained pellets of the above-mentioned compositions A to C on the absorption side were dried at 120 ℃ for 7 hours, and then injection-molded into box-shaped absorption side members A to C as shown in the absorption side member 1 of FIG. 1 at a barrel temperature of 260 ℃ and a mold temperature of 80 ℃ by an injection molding machine (manufactured by Japan Steel works, "J55").

Regarding the dimensions of the absorbent-side members A to C, in FIG. 1, the height h is 20mm and the thickness (width) w is 3 mm. On the joining surface 3 having a width w of 3mm, ridges 4 having a cross section of a substantially regular triangle with a base width of 0.75mm and a height of 0.7mm were provided so as to be 2 rows parallel (described as double) and 1 row parallel (described as single), and so as to surround the point a-b-c-d-e-f-a on the center of the width of the joining surface 3. Cross-sectional views of the vicinity of the joint surface showing the shape of the convex strip 4 are shown in fig. 2 (a) and (b). In the case of the 2-row ridges 4 shown in fig. 2 (a), the center of the width of the center of the 2-row ridge is defined as a reference, and in the case of the 1-row ridges 4 shown in fig. 2 (b), the distance between the points is defined as a-b: 80mm, b-c: 50mm, c-d: 45mm, d-e: 30mm, e-f: 35mm, f-a: 20 mm.

The height difference of the top surfaces of the protrusions 4 of the absorbent side members a to C was measured over the entire circumference. The average height difference of the top surfaces of the convex portions of the absorbing members A to C was 0.18 to 0.22mm, which is shown in Table 4 below, in each of the points a to f.

[ method for measuring melting Point Tm, crystallization temperature Tc, and melting enthalpy Δ Hm ]

The molded article of the absorption-side member thus produced was cut at a predetermined weld (a distance of 35mm from the gate), heated from 30 ℃ to 300 ℃ at a heating rate of 20 ℃/min under a nitrogen atmosphere using a Differential Scanning Calorimetry (DSC) machine ("Pyris Diamond", manufactured by PerkinElmer, inc.), held at 300 ℃ for 3 minutes, and then cooled at a cooling rate of 20 ℃/min, and the melting point Tm, the melting enthalpy Δ Hm, and the crystallization temperature Tc were measured.

[ production of Transmission-side Member D to H ]

In the production of the transmission-side member, dye pigments (Y-1) to (Y-3) were used, in which the components shown in Table 3 below were blended at the ratios shown in Table 3.

[ Table 3]

The components shown in tables 2 and 3 were mixed in amounts (parts by mass) shown in compositions D to H on the transmission side of Table 2, and the mixture was kneaded at 250 ℃ using a 30mm vented twin-screw extruder to obtain strands, thereby obtaining pellets of transmission material compositions D to H.

The obtained pellets of the above-mentioned transmitting material compositions D to H were dried at 120 ℃ for 7 hours, and then injection-molded at a barrel temperature of 260 ℃ and a mold temperature of 80 ℃ by an injection molding machine (J55, manufactured by Japan Steel works Co., Ltd.), thereby producing transmitting side members D to H having a thickness of 1mm in a shape corresponding to the joint surface 3 of the above-mentioned absorbing side members A to C and shown in FIG. 1.

The transmittance (laser wavelength 940nm) at the points a 'to f' of the planned welding lines 5 of the transmission-side member 2 corresponding to the points a-b-c-d-e-f-a of the absorption-side member 1 is as follows.

In the case of the transmissive material composition D, a': 28.1%, b': 30.2%, C': 27.3%, d': 22.4%, e': 21.4%, f': 25.3 percent,

In the case of the transmissive material composition E, a': 30.5%, b': 27.9%, C': 29.9%, d': 28.6%, e': 26.8%, f': 28.4 percent

In the case of the transmissive material composition F, a': 30.5%, b': 27.9%, C': 29.9%, d': 28.6%, e': 26.8%, f': 28.4 percent

In the case of the transmissive material composition G, a': 30.5%, b': 27.9%, C': 29.9%, d': 28.6%, e': 26.8%, f': 28.4 percent

In the case of the transmissive material composition H, a': 60.9%, b': 63.3%, C': 57.6%, d': 57.6%, e': 41.9%, f': 57.6 percent

The molded article of the transmission-side member thus produced was cut at a predetermined weld (a distance of 35mm from the gate), heated from 30 ℃ to 300 ℃ at a heating rate of 20 ℃/min under a nitrogen atmosphere using a Differential Scanning Calorimetry (DSC) machine ("Pyris Diamond", manufactured by PerkinElmer, inc.), held at 300 ℃ for 3 minutes, and then cooled at a cooling rate of 20 ℃/min, and the melting point Tm, the melting enthalpy Δ Hm, and the crystallization temperature Tc were measured.

[ evaluation of laser welding ]

Examples 1 to 10, comparative examples 1 to 5, and reference example 1

As shown in tables 4 and 5, the laser welding was performed by overlapping one of the transmission-side members a to C as the transmission side and one of the absorption-side members D to H as the absorption side, irradiating the ridge 4 of the absorption-side member 1 with the laser beam X from the peripheral edge of the transmission-side member 2 while applying a thrust per unit distance (unit: N/mm) shown in tables 4 and 5, and scanning the laser beam X along the welding planned line 5 in a winding manner. For the measurement of thrust per unit distance (N/mm), a cylinder for pressurizing (SMC cylinder) was attached

) A coin-type load cell (IMADACO., LTD., LM-20kN) was mounted on the pressurizing table, and the actual pressurizing force was measured. The obtained pressurizing force (N) is divided by the circumferential length (mm) of the planned welding line. In reference example 1,2 rows of ridges 4 (each ridge having a base with a width of 0.75mm and a height of 0.7mm and a substantially regular triangle in cross section) shown in fig. 2 (a) formed on the joining surface 3 of the cylindrical absorbing-side member 1 shown in fig. 3 (a diameter of 48mm and a height of 20mm) were irradiated with laser lightThe beam X.

In laser welding, a Fine Device co., ltd system laser Device (laser wavelength: 940nm, laser spot diameter. phi.2.1 mm, maximum power 140W, maximum scanning speed 200mm/s) was used. The welding conditions are shown in tables 4 to 5.

The laser welding strength of the welded body after welding was measured. For measurement of the bonding strength of the welded body, a tensile tester (ORIENTEC co., Ltd "1 t Tensilon") was used, and a pressing rod was attached to a test jig inserted into the welded body before welding, and the jig was loaded at 5 mm/min from the absorbent member side, thereby performing evaluation.

The amount of height reduction (amount of change) of the ridges 4 was measured by a displacement gauge attached to the pressurizing table.

The weldability is determined based on the following criteria in consideration of the load of the laser welding apparatus and the like.

A: the welding strength of the welding part is larger than 900N, and the welding speed is less than 85% of the maximum scanning speed of the laser device, namely 200 mm/s.

B: has no smoke emission, and has a bonding strength of 900N or less or a welding speed of 85% or more of the maximum speed

C: there is smoking.

The results are shown in tables 4 and 5 below.

[ Table 4]

[ Table 5]

In comparative examples 1 to 5, smoke was generated during welding and welding failure occurred, whereas in examples 1 to 10, smoke was not observed during welding and sufficient bonding strength was obtained. Example 6 was judged to be useful because it had a low strength, but was at a practical level and caused no smoke. In reference example 1, although the thrust force per unit distance was high, smoke was not observed at the time of welding because of the cylindrical symmetrical shape, and sufficient bonding strength was obtained.

Industrial applicability

The method for producing a laser-welded body of the present invention can perform laser welding with stable high welding strength even for a polyester member having a gap at the joint surface, and therefore can be suitably used for production of electric parts for transportation equipment such as automobiles, electric and electronic equipment parts, industrial machine parts, other consumer parts, and the like. Further, since the welding strength is high and as a result, the pressure resistance is also high, it is also preferably used for applications requiring airtightness, such as a container in which electric and electronic components, such as an electronic board, a circuit, a sensor, a solenoid, a motor, a transformer, and a battery, are built.

Description of the reference numerals

1: absorption side member

2: transmission-side member

3: joint surface

4: convex part (convex strip)

5: welding predetermined line

X: laser beam

Claims

1. A method for manufacturing a laser welded body, characterized in that a transmission-side member for transmitting at least a part of a laser beam and an absorption-side member for absorbing the laser beam are laser welded with a joint surface interposed therebetween, the joint surface having a shape without a symmetry axis,

the transmitting side member is formed of a composition containing a coloring material capable of transmitting and absorbing a laser beam (referred to as a "laser beam transmitting and absorbing coloring material") in a thermoplastic polyester resin, the absorbing side member is formed of a composition containing a thermoplastic polyester resin and a coloring material capable of absorbing a laser beam and not transmitting a laser beam (referred to as a "laser beam absorbing coloring material"),

2. The method of manufacturing a laser welded structure according to claim 1, wherein a height difference between a bonding surface of the absorption-side member and the transmission-side member, which is not under pressure, is 0.01mm or more.

3. The method of manufacturing a laser welded body according to claim 1 or 2, wherein a convex portion is formed on the joining surface of the absorption-side member.

4. The method of manufacturing a laser welded body according to any one of claims 1 to 3, wherein a spot diameter of the laser beam is 1.5 to 3.0 mm.

5. The method of manufacturing a laser welded body according to any one of claims 1 to 4, wherein a contour of a joint surface of the absorption-side member that is in contact with the transmission-side member is formed by 2 or more lines selected from a plurality of curved lines and straight lines having different curvatures.

6. The method of manufacturing a laser welded body according to any one of claims 1 to 5, wherein a power of the laser, a welding scheduled line, a scanning speed, and/or a scanning method are changed according to a shape of the joining surface of the absorbing-side member.

7. The method of manufacturing a laser welded structure according to any one of claims 3 to 6, wherein the amount of decrease in height of the protrusions before and after welding, of the protrusions provided on the joining surface of the absorbing-side member, is 0.06 to 0.6 mm.

8. The method of manufacturing a laser welded body according to any one of claims 1 to 7, wherein the laser beam transmittances of the joining portions of the transmission-side members are different and continuously change.

9. The method of manufacturing a laser welded body according to any one of claims 1 to 8, wherein a spot diameter of the laser beam is selected in accordance with a shape, a width, and a height of the convex portion provided on the joining surface of the absorbing-side member.

10. The method of manufacturing a laser welded structure according to any one of claims 1 to 9, wherein the laser beam transmitting/absorbing coloring material is Niger black.

11. The method of manufacturing a laser welded structure according to any one of claims 1 to 10, wherein the laser beam absorbing coloring material is carbon black.