JP7168414B2 - Laser welding body - Google Patents

Description

TECHNICAL FIELD The present invention relates to 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 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, quaterrylenes, 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 a resin that is widely used in fields such as the electric/electronics field and the automobile field because it has a high conversion rate, 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 by the above, a molten pool is formed through the laser-transmitting-absorptive molded member in the thickness direction to reach the laser-absorptive molded member. It is characterized in that even if there is a gap between it and the absorbent molded member, it is filled with the molten resin and can be welded relatively firmly.

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 is likely to occur, and gaps caused by the warping may cause uneven welding strength. Therefore, even the laser-welded body having the above structure has a problem that it is difficult to increase the welding strength.

Accordingly, the present invention provides a laser beam transmissive and absorptive molded member made of a polybutylene terephthalate material and a laser beam absorptive molded member made of a polybutylene terephthalate material. It is intended to provide a new laser-welded body that can further increase the bonding strength with respect to the laser-welded body obtained by integrating the two by laser welding.

The present invention provides a laser-welded body having a structure in which a member I and a member II are joined and integrated,
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 per 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 a polybutylene terephthalate homopolymer,
Member II comprises a polyester resin B and a coloring material capable of absorbing laser light without transmitting it (“laser light absorbing coloring material”) in an amount of 0.15 to 10.00 parts by weight per 100 parts by weight of the polyester resin B. and the polyester resin B is a resin containing any one of the following (B1), (B2) and (B3).

(B1) Polybutylene terephthalate copolymer resin (B2) Polybutylene terephthalate homopolymer (B2-1) selected from the group consisting of polybutylene terephthalate copolymer resin, polyethylene terephthalate resin, polycarbonate resin and aromatic vinyl resin A resin composition (B3) containing at least one resin (B2-2) selected from the group consisting of a polybutylene terephthalate copolymer resin (B3-1) and a polyethylene terephthalate resin, a polycarbonate resin and an aromatic vinyl resin A resin composition containing at least one resin (B3-2)

In the 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. A polybutylene terephthalate homopolymer was selected as the base resin, which enables the member I to have a transmittance of 5 to 90%. On the other hand, 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 and melts with heat to efficiently transfer heat to member I. Furthermore, since it is preferable to use a polyester resin B that is less warped in order to reduce the gap between the member I and the member II, among the above (B1), (B2) and (B3), the polyester resin B that is the base resin of the member II is Any polybutylene terephthalate resin was selected. In this way, by selecting the material compositions of members I and II in consideration of their combination, warpage is reduced, so that the gap between members I and II is reduced and the joint strength is further increased. is now possible.

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.

[This laser welded body]
A laser-welded body according to an embodiment of the present invention (referred to as "this laser-welded body") is formed by joining and integrating two members made of a polybutylene terephthalate-based material, member I and member II, by laser welding. It is a laser welded body having a configuration.
Since the present laser-welded body only has to have such a configuration, it is possible to arbitrarily have other configurations.
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.

<<Member I>>
The member I may be a member molded from a resin composition 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-based resin A preferably contains a polybutylene terephthalate homopolymer (also referred to as "homo 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 even more preferably 30 eq/ton or less.
The terminal carboxyl group content of polybutylene terephthalate homopolymer can be obtained by dissolving 0.5 g of resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol/l benzyl alcohol solution of sodium hydroxide. can.
As a method for adjusting the amount of terminal carboxyl groups, any conventionally known method may be used, such as a method of adjusting polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and a decompression method, or a method of reacting a terminal blocking agent. You can do it.

Homo PBT preferably has an intrinsic viscosity of 0.5 to 2.0 dl/g.
If the intrinsic viscosity is 0.5 dl/g or more, the mechanical strength of the weld body does not become too low. It is possible to prevent deterioration of laser weldability.
From this point of view, the intrinsic viscosity of the homo-PBT is preferably 0.5 to 2 dl/g, especially 0.6 dl/g or more or 1.5 dl/g or less, especially 0.7 dl/g or more or 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.

(Resin constituting polyester resin A)
The polyester resin A constituting the member I may contain "another resin" in addition to the homo-PBT as long as the effect of the present invention is not impaired. However, the homo PBT is preferably the main component resin of the polyester resin A constituting the member I, and the homo PBT preferably accounts for 50% by mass or more of the resin constituting the member I, especially 60% by mass or more. Among them, it is more preferable to occupy 70% by mass or more.

When polyester resin A constituting member I contains "another resin" in addition to homo-PBT, it must have a composition different from that of polyester 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 the "other resin" that can be contained in the polyester resin A include copolymerized PBT, polyethylene terephthalate resin, polycarbonate resin, aromatic vinyl resin, 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 an azine-based compound 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 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. , a yellow dye can be combined 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 further select one having a measured value (decomposition initiation temperature) of 300° C. or higher by 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 C2 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 and pigments 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 laser light 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 molded product will be weak, 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 4.0 mm, especially 0.4 mm or more or 3.5 mm or less, especially 0.5 mm or more or 3.5 mm or less. It is more preferably 0 mm or less.

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, when the reflectance of the member I is measured using light with a wavelength of 940 nm, the reflectance of the member I is preferably 1 to 90% at a thickness of 1.5 mm or more, especially 5% or more or 80% or less. 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 molded from a resin composition containing a polyester-based resin B and a laser-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 resin B preferably contains any one of (B1), (B2) and (B3) below.
By containing any one of the following (B1), (B2) and (B3) as the polyester resin B of the member II, the warpage of the member II can be reduced, and the members I and II at the time of welding can be reduced. The welding strength can be increased because the gap between them can be reduced. Also, the residual stress in the weld body can be reduced.

(B1): Polybutylene terephthalate copolymer resin (B2): Homo PBT mixed resin containing polybutylene terephthalate homopolymer (B3): Copolymerized PBT mixed resin containing polybutylene terephthalate copolymer resin

<(B1) Polybutylene terephthalate copolymer resin>
Polybutylene terephthalate copolymer resin (also referred to as “copolymerized PBT”) is a polybutylene terephthalate copolymer containing other copolymer components other than terephthalic acid units and 1,4-butanediol units.

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

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

From the viewpoint of mechanical properties and heat resistance, the copolymerized PBT preferably has a ratio of terephthalic acid in dicarboxylic acid units of 70 mol % or more, more preferably 90 mol % or more.
Also, the proportion of 1,4-butanediol in the diol units is preferably 70 mol % or more, more preferably 90 mol % or more, particularly 95 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 particularly includes polybutylene terephthalate resin obtained by copolymerizing polyalkylene glycols (especially polytetramethylene glycol (PTMG)), dimer acid-copolymerized polybutylene terephthalate resin, and especially isophthalic acid as a copolymerization component. A copolymer polybutylene terephthalate resin is preferred.

In the copolymerized PBT obtained by copolymerizing polytetramethylene glycol (PTMG), the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass, 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 copolymerized PBT, from the viewpoint of laser weldability and moldability, a copolymerized PBT obtained by copolymerizing polytetramethylene glycol or a copolymerized PBT obtained by copolymerizing isophthalic acid is particularly preferable.

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

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

<(B2) Homo PBT mixed resin composition>
The homo PBT mixed resin (B2) is a homo PBT (B2-1) and at least one resin (B2- 2) is preferably a resin composition comprising:

(Polybutylene terephthalate homopolymer (B2-1))
The polybutylene terephthalate homopolymer (B2-1) is the same as the polybutylene terephthalate homopolymer (homo PBT) as the polyester resin A.

(Polybutylene terephthalate copolymer resin (B2-2))
The polybutylene terephthalate copolymer resin (B2-2) is the same as the polybutylene terephthalate copolymer resin (B1) described above.

(Polyethylene terephthalate resin (B2-2))
The polyethylene terephthalate resin (also referred to as “PET”) is a resin containing oxyethyleneoxyterephthaloyl units composed of terephthalic acid and ethylene glycol as main structural units for all structural repeating units.
It may contain a repeating unit having a constitution other than the oxyethyleneoxyterephthaloyl unit.

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

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

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

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

The terminal carboxyl group content of PET is preferably 3 to 60 eq/ton.
By setting the amount of terminal carboxyl groups to 60 eq/ton or less, gas is less likely to be generated during melt molding of the resin material, and the resulting laser welding member tends to have improved mechanical properties. is 3 eq/ton or more, the heat resistance, retention heat stability, and hue of the member for laser welding tend to be improved, which is preferable.
From this point of view, the amount of terminal carboxyl groups of PET is preferably 3 to 60 eq/ton, more preferably 5 eq/ton or more or 50 eq/ton or less, more preferably 8 eq/ton or more or 40 eq/ton or less. preferable.
The terminal carboxyl content of polyethylene terephthalate resin is obtained by dissolving 0.5 g of polyethylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol/L benzyl alcohol solution of sodium hydroxide. is.
As a method for adjusting the amount of terminal carboxyl groups, any conventionally known method may be used, such as a method of adjusting polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and a decompression method, or a method of reacting a terminal blocking agent. You can do it.

(Polycarbonate resin (B2-2))
The polycarbonate resin (also referred to as "PC") is an optionally branched thermoplastic polymer or copolymer obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonic acid diester. is.
The method for producing PC is not particularly limited, and one produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester exchange method) can be used. Polycarbonate resin is preferred from the viewpoint of laser light transmittance and laser weldability.

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

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

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

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

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

(Aromatic vinyl resin (B2-2))
Aromatic vinyl resins are polymers having an aromatic vinyl structure as a main component. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, paramethylstyrene, vinyltoluene, and vinylxylene. can.
A copolymer obtained by copolymerizing an aromatic vinyl compound with another monomer can also be used as the aromatic vinyl resin. Typical examples include acrylonitrile-styrene copolymer (AS resin) obtained by copolymerizing styrene and acrylonitrile, maleic anhydride-styrene copolymer obtained by copolymerizing styrene and maleic anhydride (maleic anhydride-modified polystyrene resin) can be mentioned.
Representative examples of aromatic vinyl resins include polystyrene (PS), acrylonitrile-styrene (AS), methyl methacrylate-styrene (MS), and styrene-maleic acid copolymer.

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

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

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

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

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

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

(homo PBT + copolymer PBT)
When the homo PBT-based mixed resin (B2) contains the homo PBT (B2-1) and the copolymerized PBT (B2-2), the content ratio of the copolymerized PBT (B2-2) is the homo PBT (B2- 1) and copolymer PBT (B2-2) in a total of 100% by mass, preferably 10 to 90% by mass.
When the content of the copolymer PBT (B2-2) 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 copolymer PBT (B2-2) in the total 100% by mass of the homo PBT (B2-1) and the copolymer PBT (B2-2) is preferably 10 to 90% by mass. Among them, it is more preferably 15% by mass or more or 85% by mass or less, more preferably 20% by mass or more or 80% by mass or less.

(homo PBT + PET)
When the homo PBT-based mixed resin (B2) contains homo PBT (B2-1) and PET (B2-2), the content ratio of PET (B2-2) is the homo PBT (B2-1) and PET It is preferably 5 to 50% by mass in the total 100% by mass of (B2-2).
When the content of PET (B2-2) is 5% by mass or more, the laser welding performance is improved, and when the content is 50% by mass or less, moldability is improved, which is preferable.
From this point of view, the content of PET (B2-2) in the total 100% by mass of homo PBT (B2-1) and PET (B2-2) is preferably 5 to 50% by mass, especially 10% by mass. It is more preferably 15% by mass or more or 40% by mass or less.

(homo PBT + PC)
When the homo PBT mixed resin (B2) contains homo PBT (B2-1) and PC (B2-2), the content ratio of PC (B2-2) is the homo PBT (B2-1) and PC ( It is preferably 5 to 50% by mass in the total 100% by mass of B2-2).
When the content of PC (B2-2) is 5% by mass or more, laser welding performance is enhanced, and when the content is 50% by mass or less, moldability is improved, which is preferable.
From this point of view, the content of PC (B2-2) in the total 100% by mass of homo PBT (B2-1) and PC (B2-2) is preferably 5 to 50% by mass, especially 10% by mass. It is more preferably 15% by mass or more or 40% by mass or less.

(Homo PBT + aromatic vinyl resin)
When the homo PBT mixed resin (B2) contains the homo PBT (B2-1) and the aromatic vinyl resin (B2-2), the content ratio of the aromatic vinyl resin (B2-2) is the homo PBT It is preferably 5 to 50% by mass in 100% by mass in total of (B2-1) and aromatic vinyl resin (B2-2).
When the content of the aromatic vinyl resin (B2-2) is 5% by mass or more, the laser welding performance is improved, and when the content is 50% by mass or less, moldability is improved. preferable.
From this point of view, the content of the aromatic vinyl resin (B2-2) is 5 to 50% by mass in the total 100% by mass of the homo PBT (B2-1) and the aromatic vinyl resin (B2-2). Among them, the content is preferably 10% by mass or more and 45% by mass or less, and more preferably 15% by mass or more and 40% by mass or less.

In the above description, preferred content ratios are described when homo PBT (B2-1) is combined with one of copolymerized PBT, PET, PC and aromatic vinyl resin (B2-2). However, a plurality of types may be used by appropriately selecting from the above (B2-2). In addition, it is preferable that the total amount of (B2-2) does not exceed 100% by mass in each ratio range.
For example, as (B2-2), when an aromatic vinyl resin and PC are used in combination, a total of 50% by mass or more of homo PBT, 5 to 50% by mass of aromatic vinyl resin, and 5 to 50% by mass of PC is preferably 100% by mass.
Also, in (B3) described later, when multiple types are used from (B3-2), they can be combined based on the same idea as above.

<(B3) Copolymerized PBT-based mixed resin composition>
The copolymerized PBT-based mixed resin (B3) contains a copolymerized PBT (B3-1) and at least one resin (B3-2) selected from the group consisting of PET, PC and aromatic vinyl resins. It is preferably a resin composition.

At this time, the copolymerized PBT (B3-1) in the copolymerized PBT-based mixed resin (B3) is the same as the copolymerized PBT (B2-2) in the homo-PBT-based mixed resin (B2).
The PET, PC and aromatic vinyl resin in the copolymerized PBT mixed resin (B3) are the same as the PET, PC and aromatic vinyl resin in the homo PBT mixed resin (B2).

(Copolymerized PBT + PET)
When the copolymerized PBT-based mixed resin (B3) contains the copolymerized PBT (B3-1) and PET (B3-2), the content of PET (B3-2) is the copolymerized PBT (B3-1 ) and PET (B3-2) in a total of 100% by mass, preferably 50% by mass or less.
If the content of PET (B3-2) is 50% by mass or less, it is preferable because moldability is excellent.
From this point of view, the content of PET (B3-2) in the total 100% by mass of copolymerized PBT (B3-1) and PET (B3-2) is preferably 50% by mass or less, especially 5% by mass. or 40% by mass or less, more preferably 5% by mass or more or 30% by mass or less.

(Copolymerized PBT + PC)
When the copolymerized PBT-based mixed resin (B3) contains the copolymerized PBT (B3-1) and PC (B3-2), the content of PC (B3-2) is the copolymerized PBT (B3-1 ) and PC (B3-2) in a total of 100% by mass, preferably 50% by mass or less.
If the content of PC (B3-2) is 50% by mass or less, it is preferable because moldability is excellent.
From this point of view, the content of PC (B3-2) in the total 100% by mass of copolymerized PBT (B3-1) and PC (B3-2) is preferably 50% by mass or less, especially 5% by mass. or 40% by mass or less, more preferably 5% by mass or more or 30% by mass or less.

(Copolymerized PBT + aromatic vinyl resin)
When the copolymerized PBT-based mixed resin (B3) contains the copolymerized PBT (B3-1) and the aromatic vinyl-based resin (B3-2), the content ratio of the aromatic vinyl-based resin (B3-2) is , the total 100% by mass of the copolymer PBT (B3-1) and the copolymer PBT (B3-1), preferably 50% by mass or less.
If the content of the aromatic vinyl resin (B3-2) is 50% by mass or less, it is preferable because moldability is excellent.
From this point of view, the content of the aromatic vinyl resin (B3-2) in the total 100% by mass of the copolymerized PBT (B3-1) and the copolymerized PBT (B3-1) is 50% by mass or less. It is preferably 5% by mass or more and 45% by mass or less, and more preferably 5% by mass or more and 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 above-mentioned (B1), (B2) or (B3) as long as the effect of the present invention is not impaired. However, the above (B1), (B2) or (B3) is preferably the main component resin of the polyester resin B constituting the member II, and among the resins constituting the member II, (B1) and (B2) Alternatively, (B3) accounts for 50% by mass or more, preferably 60% by mass or more, and 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 homo PBT, copolymer 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, especially 50 m ² /g or more, especially 80 m ² /g or more, as measured by JIS K6217. is more preferred.

Furthermore, from the viewpoint of dispersibility, the carbon black preferably has a DBP absorption of 20 to 200 cm ³ /100 g 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, the resin heats up and melts during laser irradiation, and if the content is 10.00 parts by mass or less, rapid and excessive heat generation occurs It is preferable because it can prevent the decomposition of the resin.
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 and 1 part by mass or less. is more preferred.

The member II may or may not contain a laser light transmitting and absorbing coloring material such as nigrosine. Since the member II does not contain a laser light transmitting and absorbing coloring material, particularly nigrosine, it is possible to prevent heat-resistant discoloration and weather-resistant discoloration.

<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.

<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.

[Manufacturing method of this laser welded body]
The member I or member II may be produced by preparing a resin composition by a conventional method and molding the resin composition by a conventional method.
For example, raw materials constituting 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 blended with a part of another resin to prepare a masterbatch, which is then blended 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.

Next, the member I and the member II are superimposed on each other so that the member I side faces the light source side of the laser beam. A laser beam may be applied.
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.
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 welding strength of the present laser-welded body (welding conditions are the following welding conditions for a cup shape. Pushing force: 4.92 N/mm.) is preferably 500 N or more, more preferably 550 N or more, and still more preferably 600 N or more. is.
In addition, the compressive strength of the present laser-welded body (welding conditions are the following welding conditions for a cup shape; pushing force: 15.8 N/mm) is preferably 400 kPa or more, more preferably 600 kPa or more, and more preferably 600 kPa or more. It is preferably 800 kPa or more, more preferably 850 kPa or more, and even more preferably 1000 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.

(Welding conditions)
Laser welding machine; FD-2330 manufactured by Fine Device Co., Ltd.
Wavelength ;940nm
Output; 140W
Spot diameter; 2.1 mmφ
Scanning speed; 93mm/s
Irradiation energy: 1.51 J/mm
Scanning distance; 137mm

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.

The present invention will be described in further detail below based on 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. 5 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. 5) at the center of the side surface on the front 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")), 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 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.). 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.), as shown in FIG. A black or milky white molded body (member II) was produced.
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. 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.

<Production of laser welded body>
Next, members I and II are selected from the combinations shown in Tables 5 and 6 below, and as shown in FIG. A lid-shaped member I is placed on top of the box-shaped member II, a laser light source is placed vertically above the brim, which is the overlapped portion of the member I and the member II, and a glass plate is used to cover the member I And while applying a pressing force of 4.92 N / mm or 15.8 N / mm (pressing force at the time of welding) from both sides in the thickness direction to the overlapping part of the member II, while scanning the laser under the following conditions, 1 A circular scan was carried out and cooled to obtain a laser welded body.

The welding conditions are as follows.
Laser welding machine; FD-2330 manufactured by Fine Device Co., Ltd.
Wavelength: 940nm
Output; 140W
Spot diameter; 2.1 mmφ
Scanning speed; 93mm/s
Irradiation energy: 1.51 J/mm
Scanning distance; 137mm

<Evaluation of welding strength>
As shown in FIG. 4, measuring jigs 25 and 26 are inserted into the upper and lower surfaces of the box body composed of member I and member II respectively, and are coupled with jigs 23 and 24 housed inside, respectively, 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, it was observed whether the color material had migrated to the natural plate in contact with the member II, and evaluation was made according to the following criteria.
O (good): Bleed-out was not observed.
x (poor): Bleed-out was observed.

<Reference example>
In the combination of Comparative Example 5, welding was possible when welding was performed under the conditions of an output of 50 W, a scanning speed of 15 mm/s, an irradiation energy of 3.33 J/mm, and a pressing force during welding of 15.8 N/mm. It had a welding strength of 1322N and a compressive strength of 814N. Productivity deteriorated due to the longer scanning time. At the same time, many welding burrs were observed due to excessive energy irradiation conditions, and white powder adhered to the inside of the welded body. Contamination to the circuit was a concern.

<Comprehensive consideration>
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 with heat, it can be considered that a polybutylene terephthalate homopolymer having a transmittance of 5 to 90% is preferable as the base resin.

On the other hand, by selecting one of the following polybutylene terephthalate-based resins (B1), (B2) and (B3) as the polyester-based resin B that is the base resin of the member II, the warp of the member II is reduced. As a result, the gap between the members I and II is reduced during welding, so that the welding strength is increased and the residual stress is reduced.
(B1) Polybutylene terephthalate copolymer resin (B2) A resin composition containing polybutylene terephthalate homopolymer and at least one resin selected from the group consisting of polybutylene terephthalate copolymer resin, polyethylene terephthalate resin and polycarbonate resin. (B3) A resin composition containing a polybutylene terephthalate copolymer resin and at least one resin selected from the group consisting of polyethylene terephthalate resins and polycarbonate resins.

Member II contains a laser light-absorbing color material that can absorb laser light without transmitting it. B1) It can be considered that the polybutylene terephthalate-based resin of any one of (B2) and (B3) is preferable.
Therefore, a polybutylene terephthalate homopolymer is selected as the base resin for member I, and any one of the above polybutylene terephthalate resins (B1), (B2) and (B3) is selected as the base resin for member II. Thus, it was found that the bonding strength can be further increased.

Claims (6)

A laser welded body having a structure in which a member I and a member II are joined and integrated,
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 per 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 a polybutylene terephthalate homopolymer,
Member II comprises a polyester resin B and a coloring material capable of absorbing laser light without transmitting it (“laser light absorbing coloring material”) in an amount of 0.15 to 10.00 parts by weight per 100 parts by weight of the polyester resin B. and the polyester resin B is a resin containing any one of the following (B1) (B2) and (B3),
A laser-welded article characterized in that polyester resin A of member I and polyester resin B of member II have different compositions .
(B1) Polybutylene terephthalate copolymer resin (B2) Polybutylene terephthalate homopolymer (B2-1) and at least one resin selected from the group consisting of polybutylene terephthalate copolymer resin, polyethylene terephthalate resin and polycarbonate resin ( B2-2) a resin composition (B3) containing a polybutylene terephthalate copolymer resin (B3-1) and at least one resin (B3-2) selected from the group consisting of polyethylene terephthalate resins and polycarbonate resins A resin composition containing 2. The laser welded article according to claim 1, wherein the polybutylene terephthalate homopolymer of member I has an intrinsic viscosity of 0.5 to 2 dl/g. The polybutylene terephthalate copolymer resin of member II contains isophthalic acid as a copolymer component, and the ratio of the isophthalic acid component to the total carboxylic acid component is 1 to 30 mol % as carboxylic acid groups. Item 3. The laser-welded body according to Item 1 or 2. 4. The laser-welded product according to claim 1, wherein said laser light transmitting and absorbing coloring material contains a mixture of azine-based compounds having an azine skeleton. 5. The laser-welded body according to claim 1, wherein the laser-absorbing coloring material contains carbon black. 6. The laser welded body according to claim 1, wherein the member I is a member capable of transmitting and absorbing laser light, and the other member II is a member capable of absorbing laser light. .

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