JP7168413B2 - Manufacturing method of laser welded body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a laser-welded body having a structure in which two members made of polybutylene terephthalate-based material are joined and integrated by laser welding.

Laser welding is performed by irradiating a laser beam in the thickness direction of the resin members on the overlapping part of the two resin members, and the laser beam penetrates one of the resin members and melts the resin member near the boundary of the resin members to melt the resin. In this method, a molten pool is formed between the members, and the molten pool is cooled and solidified to join the resin members.

This kind of laser welding not only enables efficient joining without the use of joining parts or adhesives, but also makes it possible to easily join members with complicated shapes. It is widely used for joining automobile parts, electric and electronic parts, etc. It is

Regarding this type of laser welding, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-112127), a laser light transmission-absorption laser containing 0.001 to 0.3% by weight of a coloring agent consisting only of nigrosine and a thermoplastic resin is disclosed. A molded member and a laser light absorptive molded member containing 0.1 to 5% by weight of another colorant containing nigrosine and/or carbon black and a thermoplastic resin are superimposed, and are irradiated with the laser beam. A laser-welded body is disclosed which is welded and integrated by heat generation.

In addition, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2013-155277), as a resin composition used for welding by laser light, (A) 100 parts by mass of a thermoplastic polyester resin, (B) 5 to 150 parts of a reinforcing filler (C) 0 to 20 parts by weight of an impact modifier, (D) 0 to 5 parts by weight of an epoxy compound, (E) 0 to 10 parts by weight of a flow modifier, and (F) nigrosine, aniline black, Laser welding resin containing 0.001 to 0.2 parts by mass of one or more laser light absorbing dyes selected from phthalocyanines, naphthalocyanines, porphyrins, perylenes, quaterylenes, azo dyes, anthraquinones, squaric acid derivatives and immonium A composition is disclosed.

By the way, polybutylene terephthalate-based resins are not only excellent in heat resistance, mechanical strength, dimensional stability, electrical properties, oil resistance, solvent resistance, surface glossiness, colorability, flame retardancy, etc. It is widely used in fields such as electrical/electronics and automobiles because it has a high rate of transformation, good fluidity, and excellent moldability.
However, polybutylene terephthalate-based resins have relatively low laser transmittance compared to polycarbonate resins, polystyrene-based resins, etc., and are prone to warping. was

Therefore, regarding the polybutylene terephthalate-based material used for laser welding, for example, a method of using copolymerized polybutylene terephthalate (Patent Document 3 (Japanese Patent No. 3510817)), or an alloying of polybutylene terephthalate with a polycarbonate resin or a styrene resin. (Patent Document 4 (Japanese Unexamined Patent Publication No. 2003-292752) and Patent Document 5 (Japanese Patent No. 4641377)) are disclosed.

In addition, Patent Document 6 (Japanese Patent Laid-Open No. 2013-155278) describes polybutylene terephthalate resin, specific other resins, specific laser light absorbing dyes, and if necessary, reinforcing fillers, epoxy compounds, fluid As a resin composition having excellent moldability and extremely excellent laser welding workability, by using a resin composition containing a modifier etc.,
A resin composition used for welding by laser light, comprising: (A) a polybutylene terephthalate-based resin; and (B) at least one resin selected from (B-1) to (B-5) below; ) and (B) total 100 parts by mass, containing 50 to 95 parts by mass of (A) and 50 to 5 parts by mass of (B),
Furthermore, with respect to a total of 100 parts by mass of (A) and (B), (D) 0 to 120 parts by mass of reinforcing filler, (E) 0 to 5 parts by mass of epoxy compound, and (F) flow modifier 0 to 10 parts by mass, and (G) one or more laser light absorbing dyes selected from nigrosine, aniline black, phthalocyanine, naphthalocyanine, porphyrin, perylene, quaterrylene, azo dyes, anthraquinone, squaric acid derivatives and immonium disclosed is a resin composition for laser welding containing 0.001 to 0.2 parts by mass of
(B-1) Polyethylene terephthalate resin (B-2) Polycarbonate resin (B-3) Aromatic vinyl resin (B-4) Acrylic resin (B-5) Polyamide resin

JP 2007-112127 A JP 2013-155277 A Japanese Patent No. 3510817 Japanese Patent Application Laid-Open No. 2003-292752 Japanese Patent No. 4641377 JP 2013-155278 A

As in the above Patent Document 1, a laser beam transmitting and absorbing molded member containing a coloring agent consisting only of nigrosine and a laser beam absorbing molded member containing a coloring agent containing nigrosine and/or carbon black are laser welded together. In the laser-welded body integrated with the laser-transmitting/absorptive molded member, a vertically elongated molten pool is formed through the laser-transmitting/absorptive molded member in the thickness direction to the laser-absorptive molded member. It has the characteristic that it can be welded relatively firmly even if there is a gap between it and the laser light-absorbing molded member.

However, when both the laser light transmissive and absorptive molded member and the laser light absorptive molded member are made of polybutylene terephthalate homopolymer, warping tends to occur in each member. It is difficult to increase the welding strength even with the laser-welded body having the structure described above. Therefore, in order to suppress this warp, a large pressing force is applied during laser welding to correct the warp.
However, if the pressing force at this time is large, residual stress will remain in the welded body, making it likely to deteriorate over time.
Conventionally, the same spot is repeatedly irradiated with a laser several times to increase the welding strength.

Accordingly, the present invention relates to a method for manufacturing a laser-welded body in which a laser beam transmissive and absorptive molded member made of a polybutylene terephthalate-based material and a laser beam-absorbing molded member made of a polybutylene terephthalate-based material are integrated by laser welding. A new laser welded body that can reduce the pressing force that presses the joining member during laser welding, can reduce the number of times of laser irradiation, and can improve productivity by increasing the scanning speed of the laser. It is intended to provide a manufacturing method of.
A polybutylene terephthalate-based material is a material in which 50% by mass or more of the resin component constituting the material is occupied by polybutylene terephthalate or a polybutylene terephthalate copolymer.

In the present invention, the member I and the member II are superimposed and arranged so that the member I side faces the light source side of the laser beam. In a method for manufacturing a laser welded body, the overlapping portion of the member I and the member II is irradiated with a laser beam to weld and integrate the member I and the member II,
Member I consists of a polyester resin A and a color material capable of transmitting and absorbing laser light in an amount of 0.0005 to 5.0 parts by mass with respect to 100 parts by mass of the polyester resin A (“laser light transmitting and absorbing color material” and the polyester resin A is a resin containing polybutylene terephthalate homopolymer and/or polybutylene terephthalate copolymer resin,
Member II has a configuration in which one or two ridges are provided along the laser beam irradiation position of the surface in contact with member I, and the polyester resin B and 100 parts by mass of the polyester resin B 0.15 to 10.00 parts by mass of a coloring material that can absorb laser light without transmitting it (referred to as a "laser light absorbing coloring material"), and the polyester resin B is polybutylene A method for producing a laser-welded body is proposed, which is characterized by a resin composition containing a terephthalate homopolymer and an aromatic vinyl resin.

In the method for manufacturing a laser-welded body proposed by the present invention, the member I contains a laser-transmitting and absorbing color material capable of transmitting and absorbing laser light, and during laser welding, transmits and absorbs laser light, generating heat and For melting, polybutylene terephthalate homopolymer and/or polybutylene terephthalate copolymer resin that can make the transmittance of member I 5 to 90% is adopted, while for member II, the base resin of member II is used. By selecting a resin composition containing a polybutylene terephthalate homopolymer and an aromatic vinyl resin as a certain polyester resin B, the warp of member II is reduced, the gap between members I and II is reduced, and welding is achieved. Strength can be increased. As a result, according to the method for manufacturing a laser-welded body proposed by the present invention, it is possible to reduce the pressing force that presses the members to be joined during laser welding. Therefore, it is possible to more efficiently manufacture a high-quality laser-welded body.

FIG. 10 is a diagram showing an example of a protruding portion provided on the member II. FIG. 4 is a diagram illustrating a cross-sectional shape of a protruding portion provided on a member II. It is the figure which showed the member I produced in the Example. FIG. 4 is a diagram showing a member II produced in Examples. FIG. 4 is a perspective view showing an example of a state in which members I and II produced in Examples are laser-welded. FIG. 4 is an explanatory diagram of a method for measuring welding strength in Examples. FIG. 4 is an explanatory diagram of a method of measuring warpage in Examples.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below.

[Manufacturing method of this laser welded product]
In a method for manufacturing a laser welded body according to an example of the embodiment of the present invention (referred to as "this method for manufacturing a laser welded body"), member I and member II are overlapped, and the member I side becomes the light source side of the laser beam. While applying a pressing force from both sides to the surface where the member I and the member II abut against the member I and the member II, the overlapping portion of the member I and the member II is irradiated with a laser beam, This is a method for manufacturing a laser-welded body in which a member I and a member II are welded and laminated together.

The laser welding method will be described below after describing the member I and the member II.

<<Member I>>
The member I may be a member molded from a resin composition A containing a polyester-based resin A and a laser light transmitting and absorbing color material capable of transmitting and absorbing laser light.
The member I can appropriately contain components other than the polyester-based resin A and the laser light transmitting and absorbing coloring material, as will be described later.

<Polyester resin A>
The polyester resin A is preferably a resin containing a polybutylene terephthalate homopolymer (also referred to as "homo PBT") and/or a polybutylene terephthalate copolymer resin (also referred to as "copolymerized PBT").

(homo PBT)
Homo PBT is a polymer having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and is a polymer composed of terephthalic acid units and 1,4-butanediol units.

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

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

(Copolymerized PBT)
By containing the copolymerized PBT as the polyester-based resin A, the warpage of the member I is likely to be reduced, so even if the pressing pressure of the member I during welding is small, the gap during welding becomes small and the welding strength increases. , and the effect of reducing the residual stress can be obtained.

Copolymerized PBT is a polybutylene terephthalate copolymer containing other copolymerized components other than terephthalic acid units and 1,4-butanediol units.

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

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

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

Copolymerized PBT introduces a branched structure in addition to the above-mentioned bifunctional monomers. polyfunctional monomers such as acids that have the ability to form trifunctional or tetrafunctional esters such as glycerin, trimethylolpropane, pentaerythritol, etc., or monofunctional compounds such as fatty acids to adjust the molecular weight. can also

Copolymerized PBT can be modified with copolymer components.
For example, as the copolymerization component, a polybutylene terephthalate resin obtained by copolymerizing polyalkylene glycols (especially polytetramethylene glycol (PTMG)), a dimer acid-copolymerized polybutylene terephthalate resin, and particularly an isophthalic acid-copolymerized polybutylene terephthalate Resins may be mentioned.

In the copolymerized PBT obtained by copolymerizing polytetramethylene glycol (PTMG), the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass, especially 5% by mass or more or 30% by mass or less. Among them, it is more preferable that the content is 10% by mass or more or 25% by mass or less. Such a copolymerization ratio tends to provide an excellent balance between laser weldability and heat resistance, which is preferable.
On the other hand, in the case of a copolymerized PBT obtained by copolymerizing a dimer acid, the ratio of the dimer acid component to the total carboxylic acid component is preferably 0.5 to 30 mol% as a carboxylic acid group, especially 1 mol% or more. Alternatively, it is 20 mol % or less, more preferably 3 mol % or more or 15 mol % or less. Such a copolymerization ratio tends to provide an excellent balance between laser weldability, long-term heat resistance, and toughness, which is preferable.
In the case of a copolymerized PBT obtained by copolymerizing isophthalic acid, the proportion of the isophthalic acid component in the total carboxylic acid component is preferably 1 to 30 mol % as carboxylic acid groups, especially 2 mol % or more, or 20 mol % or less, more preferably 3 mol % or more or 15 mol % or less. Such a copolymerization ratio tends to provide an excellent balance of laser weldability, heat resistance, injection moldability and toughness, which is preferable.
As the copolymer PBT, a copolymer PBT obtained by copolymerizing polytetramethylene glycol or a copolymer PBT obtained by copolymerizing isophthalic acid is particularly preferable from the viewpoint of moldability.

Copolymerized PBT preferably has an intrinsic viscosity of 0.5 to 2.0 dl/g.
If the intrinsic viscosity is 0.5 dl/g or more, the mechanical strength of the weld body does not become too low. It is possible to prevent deterioration of laser weldability.
From this point of view, the intrinsic viscosity of the copolymerized PBT is preferably 0.5 to 2.0 dl/g, especially 0.6 dl/g or more or 1.5 dl/g or less, especially 0.8 dl/g or more. Alternatively, it is more preferably 1.3 dl/g or less.
The intrinsic viscosity is a value measured at 30° C. in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

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

(homo PBT + copolymer PBT)
By containing homo-PBT and copolymer PBT as the polyester-based resin A, warpage of the member I is reduced, so that the effect of increasing the welding strength and reducing the residual stress of the weld body can be obtained.

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

(Resin constituting polyester resin A)
The polyester resin A constituting the member I may contain "another resin" in addition to homo-PBT and/or copolymer PBT within a range that does not impair the effects of the present invention. However, homo PBT and / or copolymer PBT is preferably the main component resin of the polyester resin A constituting the member I, among the resins constituting the member I, homo PBT and / or copolymer PBT is 50 mass % or more, preferably 60% by mass or more, more preferably 70% by mass or more.

When polyester resin A constituting member I contains "another resin" in addition to homo-PBT and/or copolymerized PBT, it is necessary to have a composition different from that of polyester-based resin B constituting member II, which will be described later. . The term “different compositions” includes cases where the types of resins contained are different, cases where the resins contained are of the same type but at different blending ratios, and cases where the copolymerization components and copolymerization ratios constituting the resins are different. is.
Examples of "other resins" that the polyester resin A may contain include polyethylene terephthalate resins, polycarbonate resins, aromatic vinyl resins, and the like.

<Laser light transmission absorption color material>
Examples of the laser light transmitting and absorbing coloring materials contained in the member I include azine-based materials such as nigrosine and aniline black, phthalocyanine-based materials, naphthalocyanine-based materials, porphyrin-based materials, quaterrylene-based materials, azo-based materials, azomethine-based materials, anthraquinone-based materials, and squaric acid derivatives. and immonium, quinacridone, dioxazine, diketopyrrolopyrrole, anthrapyridone, isoindolinone, indanthrone, perinone, perylene, indigo, thioindigo, quinophthalone, quinoline, triphenyl Various organic dyes and pigments such as methane-based dyes can be used. One of these may be selected and used, or two or more may be used in combination.
In the present invention, the term "dye or pigment" means dye or pigment.

As the laser light transmission and absorption color material contained in the member I, among the above, in order to increase the degree of blackness, the dye and pigment (X) that mainly absorbs the wavelength of the laser light and the dye and pigment that mainly transmits the laser light ( Y) is preferably used in combination.

The dye or pigment (X) that mainly absorbs at the wavelength of the laser light preferably contains a condensed mixture of azine-based compounds having an azine skeleton.
Nigrosine is preferred as a condensed mixture of azine-based compounds having an azine skeleton.
Nigrosine acts as a dye or pigment having laser light absorption properties, and has moderate absorption in the laser light range of 800 nm to 1200 nm.

Nigrosine is C.I. I. Solvent Black 5 and C.I. I. Solvent Black 7 is a black azine-based condensation mixture as described in the Color Index.
Nigrosine can be synthesized, for example, by subjecting aniline, aniline hydrochloride and nitrobenzene to oxidation and dehydration condensation at a reaction temperature of 160 to 190° C. in the presence of iron chloride. Examples of commercially available products of nigrosine include "NUBIAN (registered trademark) BLACK series" (trade name, manufactured by Orient Chemical Industry Co., Ltd.).

On the other hand, examples of dyes and pigments (Y) that mainly transmit laser light include anthraquinone dyes and pigments, perinone dyes and pigments, and azomethine dyes and pigments.
The color of these dyes and pigments is determined by the absorption wavelength of light. A combination of dyes and pigments (hereinafter sometimes referred to as yellow dyes) and red dyes and pigments (hereinafter sometimes referred to as red dyes), dyes and pigments that exhibit purple (hereinafter sometimes referred to as purple dyes) and a combination of yellow dyes, dyes and pigments that exhibit green (hereinafter sometimes referred to as green dyes), red dyes, blue dyes, and dyes and pigments that exhibit brown (hereinafter sometimes referred to as brown dyes), etc. Combinations of dyes and pigments may be mentioned.

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

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

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

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

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

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

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

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

R ¹ to R ⁸ in formula (2) have the same definitions as R ¹ to R ⁸ in formula (1).

By metallizing this azomethine dye with a nickeling agent such as nickel acetate, a 1:1 type azomethine nickel complex is obtained as shown below.

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

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

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

The dyes and pigments (Y) that mainly transmit laser light and are used as the laser light transmitting and absorbing color material contained in member I are anthraquinone dyes and pigments (C1) having a maximum absorption wavelength in the range of 590 to 635 nm and an anthraquinone dye and pigment (C1) having a maximum absorption wavelength of It is preferable to use a perinone dye (C2) having a wavelength in the range of 460-480 nm and an anthraquinone dye (C3) having a maximum absorption wavelength in the range of 435-455 nm.
Due to the compatibility with the thermoplastic polyester resin A, the hue of the nigrosine, which is the dye and pigment (X) that mainly absorbs at the wavelength of the laser light, and the oil-soluble dye and pigment that constitutes the dye and pigment (Y) that mainly transmits the laser light are changed. Therefore, in order to obtain a jet-black molded plate suitable as a black hue, it is necessary to adjust the proportion of the oil-soluble dye/pigment constituting the dye/pigment (Y). Therefore, the content ratio of C1 to C3 is preferably C1:C2:C3=24 to 42:24 to 48:22 to 46 (based on a total of 100 parts by mass of C1, C2 and C3). A more preferred C1:C2:C3 ratio is 24-41:24-39:22-46.

Further, the dye and pigment (Y) mainly transmitting laser light used as the laser light transmitting and absorbing coloring material contained in member I are perinone dye and pigment C2 having a maximum absorption wavelength in the range of 460 to 480 nm and A coloring agent containing an anthraquinone dye/pigment C1 with a wavelength range of 590 to 635 nm in a mass ratio C2/C1 of 0.4 to 2 is preferable. Considering the color developability of the resin composition of the present invention and the suppression of bleeding out, it is more preferably 0.4 to 1.5, and still more preferably 0.6 or more or 1.5 or less.
Other dyes and pigments that may be used in combination include azo dyes, quinacridone dyes, dioxazine dyes, quinophthalone dyes, perylene dyes, perinone dyes (compounds with wavelengths different from C2 described above), isoindolinone dyes, triphenylmethane dyes, Dyes such as anthraquinone dyes (compounds having wavelengths different from those of C1 and C3 described above) and azomethine dyes can be used. However, it is preferable not to contain nickel.

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

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

The dye or pigment (Y) is preferably 0.0005 to 5 parts by weight per 100 parts by weight of the polyester resin A.
If the content of the dye or pigment (Y) that mainly transmits laser light is 5.0 parts by mass or less, bleeding out of the dye and pigment hardly occurs, which is preferable.
From this point of view, the content of the dye and pigment (Y) that mainly transmits the laser light is preferably 0.0005 to 5 parts by weight, especially 0.05 parts by weight, with respect to 100 parts by weight of the polyester resin A. It is more preferably 0.1 parts by mass or more or 3 parts by mass or less.

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

<Other ingredients>
Component I can contain various additives as desired. Such additives include, for example, reinforcing fillers, impact modifiers, flow modifiers, color auxiliaries, dispersants, stabilizers, plasticizers, UV absorbers, light stabilizers, antioxidants, antistatic agents, Inhibitors, lubricants, release agents, crystallization promoters, nucleating agents, flame retardants, epoxy compounds, and the like can be mentioned.

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

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

Since the member I must be transparent to the laser light over its entire thickness, it is not preferred that it be too thick. On the other hand, if it is too thin, the strength of the weld body is lowered, which is not preferable.
From this point of view, the thickness of the joint portion of the member I to be laser-welded is preferably 0.2 mm to 4 mm, especially 0.3 mm or more or 3.5 mm or less, especially 0.5 mm or more or 3 mm or less. is more preferred.

The transmittance of member I is not limited. However, the higher the transmittance of the member I, the easier it is for the laser beam to pass therethrough, which tends to increase the bonding strength of the molded product. Therefore, when the transmittance of the member I is measured using a light beam with a wavelength of 940 nm, the transmittance of the member I is preferably 10 to 80% when the thickness of the member I is 1.5 mm or more, especially 10% or more or 70% or less. Above all, it is preferably 15% or more or 60% or less, and among these, 20% or more or 50% or less is particularly preferable.
Also, the reflectance of the member I is not limited. However, the lower the reflectance of the member I, the less the loss of the laser light, and the more the laser light tends to enter the member I. Therefore, the reflectance of the member I is preferably 1 to 90%, especially 5% or more or 80% or less, when the member I has a thickness of 1.5 mm or more, when measured using a light beam with a wavelength of 940 nm. Above all, it is preferably 10% or more or 70% or less, and among these, 10% or more or 60% or less is particularly preferable.

<<Member II>>
The member II may be a member obtained by molding a resin composition containing a polyester-based resin B and a laser light-absorbing coloring material capable of absorbing laser light without transmitting it.
The member II can appropriately contain components other than the polyester-based resin B and the laser light-absorbing coloring material, as will be described later.

<Polyester resin B>
The polyester-based resin B is preferably a resin containing homo-PBT and an aromatic vinyl-based resin.
By containing the homo-PBT and the aromatic vinyl resin as the polyester resin B, the warp of the member II is reduced, so that the gap at the time of welding is reduced, the welding strength is increased, and the residual stress is reduced. can be obtained.

(homo PBT)
The homo PBT contained as the polyester resin B is the same as the homo PBT of the polyester resin A.

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

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

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

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

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

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

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

(Homo PBT + aromatic vinyl resin)
When polyester-based resin B contains homo-PBT and aromatic vinyl-based resin, the content ratio of homo-PBT and aromatic vinyl-based resin is not limited.
When the content of the aromatic vinyl resin is 5% by mass or more, the laser welding performance is improved, and when the content is 50% by mass or less, the moldability is improved, which is preferable.
From this point of view, the content of the aromatic vinyl resin in the total 100% by mass of the homo PBT and the aromatic vinyl resin is preferably 5 to 50% by mass, especially 10% by mass or more or 45% by mass or less, Among them, the content is more preferably 15% by mass or more or 40% by mass or less.

(Resin constituting polyester resin B)
The polyester resin B constituting the member II may contain "another resin" in addition to the homo-PBT and the aromatic vinyl resin as long as the effect of the present invention is not impaired. However, it is preferable that the homo PBT and the aromatic vinyl resin are the main component resins of the polyester resin B constituting the member II, and the homo PBT and the aromatic vinyl resin of the resin constituting the member II are 50 mass. % or more, preferably 60% by mass or more, more preferably 70% by mass or more.

When the polyester resin B constituting the member II contains the above-mentioned "other resin", it is necessary to have a composition different from that of the polyester resin A constituting the member I described above. The term “different compositions” includes cases where the types of resins contained are different, cases where the resins contained are of the same type but at different blending ratios, and cases where the copolymerization components and copolymerization ratios constituting the resins are different. is.
Examples of the "other resin" that the polyester resin B may contain include copolymerized PBT, polyethylene terephthalate resin, polycarbonate resin, and the like.

<Laser light absorption color material>
Examples of the laser light absorbing color material contained in the member II include black colorants such as carbon black, and white colorants such as titanium oxide and zinc sulfide. The above can be used in combination. Among them, those containing carbon black are preferable.

As carbon black, for example, at least one of furnace black, thermal black, channel black, lamp black and acetylene black can be used, or two or more of them can be used in combination.
It is also preferable to use carbon black that has been previously masterbatched in order to facilitate dispersion.

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

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

The content of the laser light absorbing coloring material is preferably 0.15 to 10.00 parts by mass with respect to 100 parts by mass of polyester resin B.
If the content of the laser light absorbing coloring material is 0.15 parts by mass or more, heat is generated during laser irradiation and the resin melts evenly. It is preferable because it can prevent foaming.
From this point of view, the content of the laser light absorbing coloring material is preferably 0.15 to 10.00 parts by mass with respect to 100 parts by mass of the polyester resin B, especially 5 parts by mass or less, especially 1 part by mass or less. is more preferable.

<Other ingredients>
Component II can contain various additives as desired. Such additives include, for example, reinforcing fillers, impact modifiers, flow modifiers, color auxiliaries, dispersants, stabilizers, plasticizers, UV absorbers, light stabilizers, antioxidants, antistatic agents, Inhibitors, lubricants, release agents, crystallization promoters, nucleating agents, flame retardants, epoxy compounds, and the like can be mentioned.

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

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

The transmittance of member II is preferably 10% or less at a thickness of 1.5 mm or more when measured using a light beam with a wavelength of 940 nm from the viewpoint of increasing the production efficiency and welding strength of the weld body. 5% or less, particularly preferably 0%.
Moreover, the reflectance of the member II is not particularly limited.

As shown in FIG. 1, the member II has a structure in which one or two or more ridges are provided along the laser beam irradiation position of the surface in contact with the member I. preferable.
By providing such a ridge, even if a gap occurs between the members I and II due to warpage or deformation of the members, the ridge of the member II can easily be brought into contact with the member I, resulting in stable and high welding strength. laser welding is possible.

It is preferable that the protruding portion is provided so as to extend along the welded portion. For example, as shown in FIG. 4, it can be provided so as to encircle the entire circumference of the upper surface of the absorbing member II, and in this case, it can be provided in one, two, or three or more rows.
Moreover, as shown in FIG. 2, the cross-sectional shape of the protruding portion may be semicircular, triangular, rectangular such as a trapezoid, or any other shape.

The width a of the ridge is preferably 0.05 mm to 10 mm.
It is preferable that the height b of the protruding portion, that is, the height b of the protrusion in the thickness direction of the member II is 0.005 mm to 5 mm.

When the member II consists of two ridges, the pitch c between the two ridges is preferably 0.1 mm to 10 mm. In addition, the pitch c refers to the distance between vertices in the case of a ridge having a shape with vertices, and in the case of a ridge having a shape that does not have a single vertex such as a trapezoid, each It is the distance between the center points of the width.

<Production of members I and II>
As a method for producing member I or member II, a resin composition may be prepared by a conventional method, and the resin composition may be molded by a conventional method.

First, the raw materials constituting the member I or II may be mixed and melt-kneaded by a single-screw or twin-screw extruder. Alternatively, the resin composition may be prepared without pre-mixing the respective components, or pre-mixing only a part of them, supplying the components to an extruder using a feeder, and melt-kneading them.
Alternatively, a part of the resin constituting member I or II is mixed with a part of another resin to prepare a masterbatch, which is then mixed with the remaining resin and other components and melted. It can be kneaded.
When a fibrous reinforcing filler such as glass fiber is used, it is also preferable to supply it from a side feeder in the middle of the cylinder of the extruder.

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

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

<Relationship between member I and member II>
From the viewpoint of welding strength and compressive strength, regarding the relationship between member I and member II, the difference between melting point Tm-A and crystallization temperature Tc-A of member I ((Tm-A) - (Tc-A)) is , the difference between the melting point Tm-B and the crystallization temperature Tc-B of the member II ((Tm-B)-(Tc-B)). In particular, although strongly affected by the resin used for the absorption side member, the difference between the two (((Tm-A)-(Tc-A))-((Tm-B)-(Tc-B)), "Member I -The difference in (Tm-Tc) of member II) is preferably 0 to 30 ° C., more preferably 2 ° C. or more or 20 ° C. or less, and among them 3 ° C. or more or 15 °C or below, more preferably 4°C or above or 10°C or below.
In order to achieve this, for example, adjustment of the mixing ratio of polyester resin B used in member II, selection of various additives and adjustment of blending amounts, and selection of laser light transmitting and absorbing dyes and pigments for polyester resin A used in member I and adjustment of the compounding amount. However, it is not limited to these adjustment methods.

Further, from the viewpoint of welding strength and pressure resistance, the melting enthalpy ΔHm-A of member I and the melting enthalpy ΔHm-B of member II are such that the melting enthalpy ΔHm-A of member I is the melting enthalpy ΔHm-A of polyester resin B. Higher than B is even more preferred. The difference (ΔHm-A)−(ΔHm-B) between the melting enthalpy ΔHm-A of the member I and the melting enthalpy ΔHm-B of the member II is preferably 0 to 20 J/g, especially 0.5 J/g or more. Alternatively, it is more preferably 10 J/g or less, more preferably 2 J/g or more or 9 J/g or less.
In order to achieve this, for example, adjustment of the mixing ratio of polyester resin B used in member II, selection of various additives and adjustment of blending amounts, and selection of laser light transmitting and absorbing dyes and pigments for polyester resin A used in member I and adjustment of the compounding amount. However, it is not limited to these adjustment methods.
The melting point Tm, the crystallization temperature Tc, and the melting enthalpy ΔHm are measured by cutting out a sample of the member I and the member II molded by injection molding at a distance of 5 mm or more from the gate of the injection molding die. is preferred.

<Laser welding>
In the manufacturing method of this laser welded body, the member I and the member II are superimposed and arranged so that the member I side is on the light source side of the laser beam, and the member I and the member II are arranged inward from both sides in the thickness direction. A laser beam may be applied to the overlapped portion of the member I and the member II while applying a pressing force.
The irradiated laser beam penetrates the member I in the thickness direction to form a vertically elongated molten pool up to the member II, and the molten pool cools and solidifies, so that the member I and the member II can be joined. .

When the members I and II are superimposed, they can be in surface contact or butt contact, for example. Preferably, the ridges of member II overlap member I.

When the member II has one ridge, it is preferable to irradiate the ridge with a laser beam.
On the other hand, when the member II has two ridges, it is preferable to irradiate the laser beam between the ridges.
Preferred laser welding conditions are detailed below.

(Laser welding conditions)
Next, preferable laser welding conditions will be described. However, it is not intended to be limited to the welding conditions described below.

As for the laser welding conditions, it is preferable to appropriately select preferable conditions according to, for example, the specifications of the device, the type of laser, the diameter of the laser, the laser output, and the scanning speed.

Examples of the type of laser light to be irradiated include solid lasers, fiber lasers, semiconductor lasers, gas lasers, liquid lasers, and the like. For example, YAG (yttrium aluminum garnet crystal) laser (wavelength 1064 nm, 1070 nm), LD (laser diode) laser (wavelength 808 nm, 840 nm, 940 nm, 980 nm), etc. can be preferably used. Among them, laser beams with wavelengths of 940 nm, 980 nm and 1070 nm are preferable.
The oscillation form may be either CW or pulse.
The irradiation method is also not particularly limited. For example, a method in which a laser head is moved by a robot, a galvano scan method in which a laser beam is reflected by a mirror and scanned, a method in which a large number of laser heads are equipped and the welding surface is irradiated simultaneously can be selected as appropriate.

The laser spot diameter is preferably 0.1 mm or more and 30 mm or less, more preferably 0.2 mm or more or 10 mm or less, and more preferably 0.7 mm or more or 3.0 mm or less.
If the laser spot diameter is 0.1 mm or more, welding for obtaining a desired welding strength can be easily performed, and if it is 30 mm or less, the welding width can be easily controlled. Note that the spot diameter of the laser beam can be selected according to the width and height of the welding surface.
Moreover, the laser beam may be focused on the joint surface or may be defocused, and it is preferable to appropriately select the laser beam according to the desired weld body.

The laser output is preferably 1 W to 1000 W, more preferably 10 W or more or 500 W or less, more preferably 15 W or more or 200 W or less.
If the laser output is 1000 W or less, it is possible to prevent the cost of laser welding equipment from becoming too high, and if it is 1 W or more, sufficient welding strength can be easily obtained.
The laser scanning speed is preferably 0.1 mm/s to 20000 mm/s, more preferably 1 mm/s or more or 10000 mm/s or less, and more preferably 10 mm/s or more or 1000 mm/s or less.
Regarding the laser scanning method, the output of the laser, the line to be welded, the scanning speed, and/or the scanning method are adjusted according to the shape of the joint surface from the viewpoint of welding efficiency, welding strength, welding appearance, and equipment load. is preferred.

In carrying out laser welding, first, the member I and the member II are overlapped, and the state in which the member I and the member II are overlapped is maintained. When maintaining the superimposed state, a transparent plate material such as a glass plate, a quartz plate, or an acrylic plate may be arranged on the transmission side member I, that is, on the laser irradiation side. In particular, when a glass plate or quartz plate is arranged, it is suitable for facilitating the dissipation of heat generated during laser welding and obtaining a good appearance.

Next, from above the member I, a laser beam is scanned and irradiated onto the portion to be welded corresponding to the peripheral edge of the member II. At this time, most or most of the laser light is transmitted through the member I and partially absorbed. Then, the laser light is absorbed by the joint surfaces of the member I and the member II, and the vicinity of the surfaces of the joint surfaces generates heat and melts.
By doing so, the joining surface of the member II and the member I are fused together, and after the irradiation of the laser beam is stopped, the melted portions of the member I and the member II are cooled and solidified to raise the height of both members. It can be strongly welded and integrated.

At this time, it is preferable to apply a pressing force (N/mm) to both members by means of a jig or pressure means at least when the two members are joined by laser welding.
The pressing force (N/mm) is preferably 0.0002 N/mm or more and 160 N/mm or less, especially 80 N/mm or less, especially 50 N/mm or less, especially 40 N/mm or less, especially 30 N/mm or less. mm or less, particularly preferably 20 N/mm or less. By applying a pressing force within this range, residual stress is less likely to remain in the molded product, warping deformation is reduced, and sufficient welding strength can be easily obtained.
On the other hand, the lower limit is preferably 0.4 N/mm or more. By setting it to 0.4 N/mm or more, it is easy to maintain sufficient adhesion between the joint surfaces, and it is easy to achieve sufficient welding.
However, when welding a member with a long laser scanning distance, for example, a member with a laser scanning distance of 200 mm or more, the pressing force (N/mm) is preferably 10 N/mm or less, particularly 9 N/mm. mm or less, more preferably 5 N/mm or less, most preferably 3 N/mm or less.

The above pushing force (N/mm) is the pushing force per unit distance. Imada, LM-20M) and measure the actual pushing force (N). Then, the value obtained by dividing the obtained actual pressing force (N) by the length (mm) of one circumference of the line to be welded can be obtained as the pressing force per unit distance (N/mm).
By doing so, the joining surface of the member II and the member I are fused together, and after the irradiation of the laser beam is stopped, the melted portions of the member I and the member II are cooled and solidified to combine the two members. It can be welded and integrated with high strength.

The compressive strength of the present laser welded body (welding conditions are the following welding conditions in the case of a cup shape; pushing force: 15.8 N/mm) is preferably 400 kPa or more, more preferably 600 kPa or more, and still more preferably 850 kPa or more.
In addition, in the measurement of the various strengths described above, test pieces of a size that can be welded with the described pressing force are used.

(Laser welding conditions)
Wavelength ;940nm
Output: 140W
Spot diameter: 2.1mmφ
Scanning speed; 93mm/s
Irradiation energy; 1.51 J/mm
Scanning distance: 137mm
Scan frequency ;1

The shape, size, thickness, etc. of the present laser-welded body are arbitrary, and can be used for various purposes. Examples include electrical parts for transportation equipment such as automobiles, electrical and electronic parts, parts for industrial machinery, and other parts for consumer use. It is particularly preferable to use it for uses that require airtightness, such as containers for housing electrical and electronic components such as circuits, sensors, solenoids, motors, transformers, and batteries.

<Explanation of terms>
In this specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), "preferably larger than X" or "preferably less than Y" It also includes intent.

Hereinafter, the present invention will be described in further detail based on the following examples and comparative examples.

<Optical properties: measurement of transmittance and reflectance>
Resin composition pellets obtained in the following examples and comparative examples, that is, resin composition pellets for forming member I shown in Table 3 below or resin composition pellets for forming member II shown in Table 4 below , After drying for 7 hours at 120 ° C., using an injection molding machine (“NEX80-9E” manufactured by Nissei Plastic Industry Co., Ltd.), a cylinder temperature of 260 ° C., a mold temperature of 60 ° C., and the following injection conditions, transmittance, A 60 mm x 60 mm x 1.5 mm thick flat test piece for reflectance measurement was injection molded.

(Injection condition)
Holding pressure time: 15 sec
Cooling time: 15 sec
Injection speed: 120mm/sec
Back pressure: 4MPa
Screw rotation speed: 80 rpm

Of the test piece (60 mm × 60 mm × 1.5 mm thick) obtained above, from the point 35 mm from the side of the gate, 10 mm wide and 20 mm long, and at the center of the width of the test piece, UV-visible Using a near-infrared spectrophotometer ("UV-3100PC" manufactured by Shimadzu Corporation), the transmittance (%) and reflectance (%) at a wavelength of 940 nm are obtained, and the transmittance and reflectance of member I and member II are obtained. It is shown in the table below.

<Method for measuring color tone>
Resin composition pellets obtained in the following examples and comparative examples, that is, resin composition pellets for forming member I shown in Table 3 below or resin composition pellets for forming member II shown in Table 4 below , After drying for 7 hours at 120 ° C., using an injection molding machine (“NEX80-9E” manufactured by Nissei Plastic Industry Co., Ltd.), a cylinder temperature of 260 ° C., a mold temperature of 60 ° C., and the above transmittance and reflectance measurement A flat test piece of 60 mm×60 mm×thickness 3 mm for color tone measurement was injection molded under the same injection conditions as when the test piece was molded.
The L* value (SCE) of the flat test piece obtained above was measured and shown in the table below as the L ^* value of member I or II. Measurement was performed using a spectrophotometric color difference meter (Konica Minolta Optics, CM-3600d) compliant with ISO7724/1, D65/10 (reflected illumination, 10° direction light reception), SCE (specular reflection removed) colorimetry. It was measured using a target mask CM-A (φ8 mm) according to the method.

<Method for measuring the amount of warpage>
Resin composition pellets obtained in the following examples and comparative examples, that is, resin composition pellets for forming member I shown in Table 3 below or resin composition pellets for forming member II shown in Table 4 below , After drying at 120 ° C. for 7 hours, using a "model SE-50D" injection molding machine manufactured by Sumitomo Heavy Industries, under the conditions of a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C., the rectangular parallelepiped shown in FIG. A box-shaped molding was molded.
FIG. 7 is a perspective view of the box-shaped molding used for evaluation of warpage, showing a state in which the bottom surface is turned down. The box-shaped body has a width of 25 mm, a length of 30 mm, a height of 25 mm, and a wall thickness of 1 mm on the bottom surface and 0.5 mm on the other side surfaces. The gate is a substantially elliptical one-point gate with a major axis of 2.0 mm and a minor axis of 1.5 mm, and is a submarine gate (GATE in FIG. 7) at the center of the side surface on the near side in FIG.

Place the molded product after molding so that the bottom of the box faces downward, and measure the inward warp length L of the top of the inner side surface when the inner side surface in FIG. mm) and shown in the table below as the amount of warpage of member I or II.
The smaller this value, the smaller the amount of inward warpage of the molded product, and the better the dimensional accuracy.

<Methods for measuring melting point Tm, crystallization temperature Tc, and melting enthalpy ΔHm>
After drying the resin composition pellets obtained in the following examples and comparative examples, that is, the resin composition pellets for forming member I shown in Table 3 below at 120 ° C. for 7 hours, an injection molding machine (Japan Steel Works, Ltd.) ("J55" manufactured by J55)), and molded at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C. to produce a black or milky white molded body (member I) with a thickness of 1.5 mm as shown in FIG. .
The part to be welded (distance from the gate: 33 mm part) of the molded body of the produced member I was cut, and a differential scanning calorimeter (DSC) machine ("Pyris Diamond" manufactured by PerkinElmer) was used to measure the temperature under a nitrogen atmosphere. The temperature was raised from 30° C. to 300° C. at a temperature increase rate of 20° C./min, held at 300° C. for 3 minutes, and then cooled at a temperature decrease rate of 20° C./min. were measured and shown as Tm, Tc, Tm-Tc and ΔHm of member I in the table below.

<Production of member I>
In the production of member I, dyes and pigments containing the components shown in Table 2 below in the proportions shown in Table 2 were used.

The components shown in Table 3 below were placed in a stainless steel tumbler at the mixing ratios shown in Table 3, and stirred and mixed for 1 hour. The resulting mixture was put into the main hopper of a 30 mm vent-type twin-screw extruder (manufactured by Japan Steel Works, Ltd., "TEX30α"). C., a die at 250.degree. C., a screw speed of 200 rpm and a discharge rate of 40 kg/hour.
After drying the obtained pellets at 120 ° C. for 7 hours, they were molded at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C. using an injection molding machine (“J55” manufactured by Japan Steel Works, Ltd.), as shown in FIG. A black or milky white molded body (member I) having a thickness of 1.5 mm was produced.

<Production of member II>
The components shown in Table 4 below were placed in a stainless steel tumbler at the mixing ratio shown in Table 4, and mixed with stirring for 1 hour. The resulting mixture was put into the main hopper of a 30 mm vent-type twin-screw extruder (manufactured by Japan Steel Works, Ltd., "TEX30α"). C., a die at 250.degree. C., a screw speed of 200 rpm and a discharge rate of 40 kg/hour.
After drying the obtained pellets at 120 ° C. for 7 hours, they were molded at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C. using an injection molding machine (“J55” manufactured by Japan Steel Works, Ltd.). A circular cup-shaped black or milky-white molding (member II) with a flange was produced. The ridges were provided as one or two ridges on the upper surface of the brim of the circular cup along the periphery, and were provided by integral molding when the molded body was produced. The dimensions are 0.7 mm in height and 1.5 mm in width when there is one ridge (described as single in the table), and 0.7 mm in height and 1.5 mm in width when there are two ridges (described as double in the table). The projections were of the same shape with a height of 0.7 mm, a width of 0.46 mm and a pitch of 0.5 mm.
The optical properties, color tone, amount of warpage, melting point Tm, melting enthalpy ΔHm, and crystallization temperature Tc were measured in the same manner as described for member I. Further, the melting point Tm, the melting enthalpy ΔHm, and the crystallization temperature Tc were measured at the portion to be welded (distance from the gate: 42 mm portion) of the compact of the member II produced.

A combination of members I and II shown in Tables 5 and 6 below was selected, and as shown in FIG. Then, a lid-shaped member I is placed on the box-shaped member II, a laser light source is arranged vertically above the collar portion where the member I and the member II overlap, and a glass plate is used to separate the member I and the member II. While applying a pressing force (pressing pressure at the time of welding) from both sides in the thickness direction to the overlapping part, that is, the contact surface of both, using "FD-2330 manufactured by Fine Device" as a laser welding machine, the following laser Under welding conditions 1 to 6, a laser beam was scanned, irradiated, and cooled to obtain a laser-welded body.
As welding conditions, the following laser welding conditions 1 to 6 were adopted.

(Laser welding condition 1)
Wavelength ;940nm
Output: 140W
Spot diameter: 2.1mmφ
Scanning speed; 93mm/s
Irradiation energy; 1.51 J/mm
Scanning distance: 137mm
Scan frequency ;1
Pushing force: 15.8N/mm

(Laser welding condition 2)
Wavelength ;940nm
Output: 100W
Spot diameter: 2.1mmφ
Scanning speed; 100mm/s
Irradiation energy; 1.00 J/mm
Scanning distance: 137mm
Scan frequency ;2
Pushing force: 15.8N/mm

(Laser welding condition 3)
Wavelength ;940nm
Output: 100W
Spot diameter: 2.1mmφ
Scanning speed; 80mm/s
Irradiation energy; 1.25 J/mm
Scanning distance: 137mm
Scan frequency ;2
Pushing force: 15.8N/mm

(Laser welding condition 4)
Wavelength ;940nm
Output: 140W
Spot diameter: 2.1mmφ
Scanning speed; 20mm/s
Irradiation energy; 7.00 J/mm
Scanning distance: 137mm
Scan frequency ;1
Pushing force: 15.8N/mm

(Laser welding condition 5)
Wavelength ;940nm
Output: 140W
Spot diameter: 2.1mmφ
Scanning speed; 93mm/s
Irradiation energy; 1.51 J/mm
Scanning distance: 137mm
Scan frequency ;1
Pushing force: 25.5N/mm

(Laser welding condition 6)
Wavelength ;940nm
Output: 140W
Spot diameter: 2.1mmφ
Scanning speed; 40mm/s
Irradiation energy; 4.67 J/mm
Scanning distance: 137mm
Scan frequency: 2
Pushing force: 15.8N/mm

<Evaluation of welding strength>
As shown in FIG. 6, measuring jigs 25 and 26 are inserted into the upper and lower surfaces of the box made up of member I and member II respectively, coupled with jigs 23 and 24 housed inside, and pulled up and down. (tensile speed: 5 mm/min), the strength (welding strength) at which member I and member II separate was measured. However, when the member I and the member II separated before the test, the test could not be performed (indicated as "impossible" in the table).
As an apparatus, an Instron 5544 universal testing machine was used.

<Evaluation of compressive strength>
A hole of φ3.5 mm is made at the location of the protrusion in the center of member I of the welding body welded under a pressing force of 15.8 N/mm, and then a water injection coupler is joined. First, the inside of the weld body is filled with water, and then immersed in water at 25°C. Next, water is supplied to the interior of the welded body, and the internal pressure of the welded body is increased in increments of 196 kPa. However, when the member I and the member II separated before the test, the test could not be performed (indicated as "impossible" in the table).
In addition, the apparatus used the Toyo Seiki Co., Ltd. "bottle pressure resistance tester."

<Bleed resistance>
The welded body prepared above was placed on a PBT homopolymer resin (NOVADURAN (registered trademark) 5010R5 natural) plate (hereinafter referred to as a natural plate) so that the member II was on the bottom, and placed in an oven at 120 ° C. for 8 hours. After heating for a period of time, it was observed whether or not the color material had migrated to the natural plate in contact with member II, and evaluation was made according to the following criteria.
O (good): Bleed-out was not observed.
x (poor): Bleed-out was observed.

From the above examples and the test results conducted by the present inventors so far, the member I contains a laser light transmitting and absorbing color material capable of transmitting and absorbing laser light, and at the time of laser welding, it transmits and absorbs laser light. However, since it melts exothermically, it is preferable to use a polybutylene terephthalate homopolymer and/or polybutylene terephthalate copolymer resin, which can adjust the transmittance of the member I to 5 to 90%, as the base resin of the member I. can think.
On the other hand, by selecting a resin containing a polybutylene terephthalate homopolymer and an aromatic vinyl resin as the polyester-based resin B that is the base resin of the member II, the warp of the member II is reduced, so that it can be welded with the member I at the time of welding. It was found that the weld strength increased and the residual stress decreased because the gap between IIs decreased. Member II contains a laser light-absorbing coloring material that can absorb laser light without transmitting it, and during laser welding, it absorbs laser light, heats and melts, and transmits heat to the transparent material, so polybutylene terephthalate homopolymer and It can be considered that a resin containing an aromatic vinyl resin is preferable.
As a result, it is possible to reduce the pressing force that presses the members to be joined during laser welding, reduce the number of laser irradiation times, and increase the scanning speed of the laser, thereby improving productivity.

Claims (9)

The member I and the member II are placed on top of each other so that the member I side faces the laser light source side. In a method for manufacturing a laser welded body in which the overlapping portion of II is irradiated with a laser beam to weld and integrate the member I and the member II,
Member I consists of a polyester resin A and a color material capable of transmitting and absorbing laser light in an amount of 0.0005 to 5.0 parts by mass with respect to 100 parts by mass of the polyester resin A (“laser light transmitting and absorbing color material” and the polyester resin A is a resin containing polybutylene terephthalate homopolymer and/or polybutylene terephthalate copolymer resin,
Member II has a configuration in which one or two ridges are provided along the laser beam irradiation position of the surface in contact with member I, and the polyester resin B and 100 parts by mass of the polyester resin B 0.15 to 10.00 parts by mass of a coloring material that can absorb laser light without transmitting it (referred to as a "laser light absorbing coloring material"), and the polyester resin B is polybutylene A resin composition containing a terephthalate homopolymer and an aromatic vinyl resin ,
A method for producing a laser-welded body, wherein polyester resin A of member I and polyester resin B of member II have different compositions . 2. The method for manufacturing a laser welded product according to claim 1, wherein a pressing force of 0.0002 to 160 N/mm is applied from both sides to the contact surfaces of the member I and the member II. 3. The method for producing a laser-welded product according to claim 1, wherein a laser beam having a wavelength of 800 to 1200 nm is irradiated with an output of 1 to 1000 W while scanning at a speed of 1 to 10000 mm/sec. 4. The production of the laser welded body according to any one of claims 1 to 3, wherein each of the ridges of member II has a width of 0.05 mm to 10 mm and a height of 0.05 mm to 5 mm. Method. 5. The method for manufacturing a laser-welded body according to claim 1, wherein the member II has two ridges with a pitch of 0.1 mm to 10 mm. 6. The method for producing a laser welded product according to claim 1, wherein the polybutylene terephthalate homopolymer of member I has an intrinsic viscosity of 0.5 to 2 dl/g. 7. The laser according to any one of claims 1 to 6 , wherein the polyester resin B of member II comprises 50 to 95% by mass of polybutylene terephthalate homopolymer and 5 to 50% by mass of aromatic vinyl resin. A method for manufacturing a welded body. 8. The method for producing a laser-welded body according to claim 1 , wherein the laser light transmitting and absorbing coloring material is a mixture of azine-based compounds having an azine skeleton. 9. The method for producing a laser - welded body according to claim 1, wherein the laser-absorbing coloring material contains carbon black.

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