Material for laser welding

Abstract

Disclosed is a material for laser welding, which contains a resin and a cyanine compound represented by the following formula (1), wherein the cyanine compound has an average transmittance of 81% or more in the wavelength range of 380 nm to 780 nm when the transmittance at the maximum absorption wavelength is 10% in the wavelength range of 300 nm to 1,300 nm. (In formula (1), L represents a methine chain having carbon atoms 3 to 9 inclusive, methine groups contained in the methine chain may each independently have substituent groups, the substituent groups may be connected to each other, A+ and A represent a group that is bonded to the methine chain L, and X- represents a monovalent anion, a conjugate acid of which has a pKa of -8.0 or less.)

Description

Laser welding materials

[0001] The present invention relates to a laser-weldable material, specifically to a laser-weldable material containing a resin and a cyanine compound. The present invention also provides a laminate having a light-absorbing layer formed from the laser-weldable material of the present invention, and an absorber formed from the laser-weldable material of the present invention.

[0002] Laser welding is a joining method in which components are welded together by irradiating them with laser light. Laser welding typically involves overlapping a transparent material that transmits laser light with an absorbing material that absorbs laser light, and then irradiating the laser light from the transparent material side to join the transparent and absorbing materials. Resins containing coloring pigments such as carbon black or black dyes are used as absorbing materials. By using such absorbing materials, the energy of the laser light is efficiently absorbed by the absorbing material, allowing for favorable laser welding. However, in this case, since the transparent and absorbing materials have different colors, the joint between the transparent and absorbing materials is noticeable, which may limit the uses of the welded body obtained by welding the transparent and absorbing materials. In response to this, Patent Document 1 discloses a laser welding material containing a specific squarylium compound as a dye that absorbs laser light. The laser welding material of Patent Document 1 allows transparent resins to be laser welded together, has high invisibility, and makes the joint formed by laser welding less noticeable.

[0003] JP 2019-11455 A

[0004] It is desirable for the laser welding material to have a high visible light transparency of the dye that absorbs laser light, which makes it easy to match the color of the laser welding material to the color of the members to be joined or to form it in any color, thereby widening the range of applications. The present invention was made in consideration of the above circumstances, and its object is to provide a laser welding material that can be suitably used for laser welding and in which the laser beam-absorbing dye has high visible light transparency. The present invention also provides a laminate having a light-absorbing layer formed from the laser welding material of the present invention, and an absorber formed from the laser welding material of the present invention.

[0005] The laser weldable material, laminate, and absorber of the present invention, which can solve the above-mentioned problems, are as follows: [1] A laser weldable material containing a resin and a cyanine compound represented by the following formula (1), [In formula (1), L represents a methine chain having 3 to 9 carbon atoms, and each methine group contained in the methine chain may independently have a substituent, and the substituents may be linked to each other; A ＋ and A represents a group bonded to the methine chain L; X － represents a monovalent anion having a pKa of -8.0 or less of the conjugate acid.] The cyanine compound has a laser welding material in which, when the transmittance at the absorption maximum wavelength is 10% in the wavelength range of 300 nm to 1300 nm, the average transmittance in the wavelength range of 380 nm to 780 nm is 81% or more. [2] The laser welding material according to [1], wherein the cyanine compound has a maximum absorption wavelength in the wavelength range of 750 nm to 1300 nm. [3] The laser welding material according to [1] or [2], further containing a solvent. [4] The laser welding material according to any one of [1] to [3], wherein the resin is a thermoplastic resin. [5] The laser welding material according to any one of [1] to [4], wherein the resin is a (meth)acrylic resin containing a structural unit having a ring structure in the main chain, and the ring structure contains at least one selected from the group consisting of a lactone ring structure, a glutarimide structure, and a maleimide structure. [6] In the formula (1), A ＋ and A represents any one of groups represented by the following formulas (2) to (7): [1] The laser welding material according to any one of [1] to [5]. [In formula (2), R １１ represents an organic group, R １２ ~R １７ each independently represents a hydrogen atom, a halogen atom, or an organic group, and * represents the bonding site with the methine chain L in formula (1). [In formula (3), R ２１represents an organic group, ring S represents a hydrocarbon ring having a fused ring structure which may have a substituent, or a heterocycle having a fused ring structure which may have a substituent, and is spiro-bonded to the adjacent pyrrole ring, ring T represents an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, or a fused ring containing these ring structures which may have a substituent, and * represents the bonding site to the methine chain L in formula (1). [In formula (4), R ３１ represents an organic group, R ３２ ~R ３５ each independently represents a hydrogen atom, a halogen atom, or an organic group, or R ３２ and R ３３ , R ３３ and R ３４ , R ３４ and R ３５ may be linked to each other to form a ring, and Y １ represents an oxygen atom, a sulfur atom, CH═CH, or CR ３６ R ３７ represents R ３６ and R ３７ represents an organic group, and * represents a bonding site with the methine chain L in formula (1). [In formula (5), R ４１ ~R ４４ each independently represents a hydrogen atom, a halogen atom, or an organic group, or R ４１ and R ４２ , R ４３ and R ４４ may be linked to each other to form a ring, and Y ２ is an oxygen atom, a sulfur atom, or NR ４５ represents R ４５ represents an organic group, and * represents the bonding site with the methine chain L in formula (1). [In formula (6), R ５１ ~R ５４ each independently represents a hydrogen atom, a halogen atom, or an organic group; Y ３ is an oxygen atom, a sulfur atom, or NR ５５ represents R ５５ represents an organic group, and * represents the bonding site with the methine chain L in formula (1). [In formula (7), R ６１~R ６３ , R ６５ ~R ６７ each independently represents a hydrogen atom, a halogen atom, or an organic group; R ６４ represents an organic group, and * represents a bonding site with the methine chain L in formula (1).] [7] A laminate having a substrate and a light-absorbing layer provided on the substrate and formed from the laser welding material according to any one of [1] to [6]. [8] The laminate according to [7], wherein the light-absorbing layer has an average transmittance of 80% or more in a wavelength range of 380 nm to 780 nm. [9] An absorber formed from the laser welding material according to any one of [1] to [6].

[0006] The laser welding material of the present invention can suitably weld members together by irradiating them with laser light, and since the cyanine compound contained therein has high visible light transmittance, it can be easily formed into any color, thereby widening the range of applications.

[0007] 1 shows the transmission spectrum of the light absorbing layer of resin substrates B1 to B4 produced in the examples. 2 shows the transmission spectrum of the light absorbing layer of resin substrates B5 and B6 produced in the examples. 3 shows the transmission spectrum of the light absorbing layer of resin substrates B7 to B9 produced in the examples. 4 shows the transmission spectrum of the light absorbing layer of resin substrate B10 produced in the examples. 5 shows the transmission spectrum of the light absorbing layer of resin substrate B11 produced in the examples. 6 shows the transmission spectrum of resin substrate D1 produced in the examples. 7 shows the transmission spectrum of resin substrates D2 and D3 produced in the examples. 8 shows the transmission spectrum of resin substrate D4 produced in the examples. 9 shows the transmission spectrum of resin substrate D5 produced in the examples. 10 shows the transmission spectrum of resin substrate D6 produced in the examples. 11 shows the transmission spectrum of the dye component of resin substrate D1 produced in the examples. 12 shows the transmission spectrum of the dye component of resin substrate D2 and D3 produced in the examples. 13 shows the transmission spectrum of the dye component of resin substrate D4 produced in the examples. 14 shows the transmission spectrum of the dye component of resin substrate D5 produced in the examples. 1 shows the transmission spectrum of the dye component of resin substrate D6 produced in the example.

[0008] The present invention relates to a laser-weldable material containing a resin and a cyanine compound. The laser-weldable material is used to weld members together by irradiating them with laser light, and when irradiated with laser light, the laser-weldable material absorbs the laser light and generates heat, thereby welding the members together.

[0009] The laser welding material of the present invention uses a cyanine compound as a dye that absorbs laser light. Laser welding uses laser light having a wavelength of, for example, 800 nm to 1300 nm, and cyanine compounds can effectively absorb light in this wavelength range and function as a heat source. On the other hand, cyanine compounds have high transmittance to light in the visible light range and excellent invisibility. Therefore, the laser welding material of the present invention can be substantially free of coloring derived from the cyanine compound, making it easy to match the color of the laser welding material with that of the transmitting material or to form it into any color, thereby broadening its range of applications. The laser welding material of the present invention can be used to form an absorbing material that absorbs laser light, or to form a light-absorbing layer that is disposed between components to be laser welded and that joins these components. In the latter case, at least one of the components to be laser welded is a transmitting material that transmits laser light. The laser welding material of the present invention is described in detail below.

[0010] The laser welding material of the present invention contains a resin and a cyanine compound represented by the following formula (1): In formula (1), L represents a methine chain having 3 to 9 carbon atoms, and each methine group contained in the methine chain may independently have a substituent, and the substituents may be linked to each other; ＋ and A represents a group bonded to the methine chain L; X － represents a monovalent anion whose conjugate acid has a pKa of −8.0 or less. The cyanine compound of formula (1) also includes compounds in a resonance relationship.

[0011]

[0012] In formula (1), L represents a methine chain having 3 to 9 carbon atoms, i.e., a methine chain in which 3 to 9 methine groups (-CH=) are connected to form a conjugated double bond. Each methine group (i.e., a hydrogen atom on a methine group) included in the methine chain may independently have a substituent, and the substituents may be linked to each other. Examples of the substituent that the methine group may have (hereinafter, sometimes referred to as "substituent P") include a halogeno group (halogen atom) and an organic group. Note that, when a methine group included in the methine chain has a substituent, the number of carbon atoms in the methine chain means the number of carbon atoms excluding the substituent.

[0013] The methine chain L preferably has an odd number of linked methine groups, and therefore preferably has 3, 5, 7, or 9 carbon atoms, and preferably has 3, 5, 7, or 9 linked methine groups. In this case, the methine compound represented by formula (1) is represented by the following formulas (1A) to (1D). In formulas (1A) to (1D), R ７１ ~R ７９ each independently represents a hydrogen atom, a halogen atom or an organic group.

[0014]

[0015] Examples of the organic group of the substituent P that the methine group may have include an alkyl group, an alkoxy group, an alkylthio group, an alkoxycarbonyl group, an alkylsulfonyl group, an alkylsulfinyl group, an aryl group, an aralkyl group, an aryloxy group, an arylthio group, an aryloxycarbonyl group, an arylsulfonyl group, an arylsulfinyl group, a heteroaryl group, an amino group, an amide group, a sulfonamide group, a carboxy group (a carboxylic acid group), and a cyano group.

[0016] Examples of the alkyl group for the substituent P include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl. The alkyl group may have a substituent, and examples of the substituent for the alkyl group include aryl, heteroaryl, halogeno, hydroxyl, carboxy, alkoxy, cyano, nitro, amino, and sulfo groups. Examples of alkyl groups having a halogeno group include monohalogenoalkyl groups, dihalogenoalkyl groups, alkyl groups having a trihalomethyl unit, and perhalogenoalkyl groups. As the halogeno group, a fluorine atom, a chlorine atom, or a bromine atom is preferred, with a fluorine atom being particularly preferred. The number of carbon atoms in the alkyl group (the number of carbon atoms excluding substituents) is preferably 1 to 20. Specifically, if the alkyl group is a linear or branched alkyl group, the number of carbon atoms is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5, and if the alkyl group is a cyclic alkyl group, the number of carbon atoms is preferably 4 to 10, and more preferably 5 to 8.

[0017] For specific examples of the alkyl group contained in the alkoxy group, alkylthio group, alkoxycarbonyl group, alkylsulfonyl group, and alkylsulfinyl group of the substituent P, see the above description of the alkyl group.

[0018] Examples of the aryl group for the substituent P include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, and an indenyl group. The aryl group may have a substituent, and examples of the substituent that the aryl group has include an alkyl group, an alkoxy group, a heteroaryl group, a halogeno group, a halogenoalkyl group, a hydroxyl group, a cyano group, a nitro group, an amino group, a thiocyanate group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfo group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, and a sulfamoyl group. The number of carbon atoms in the aryl group (the number of carbon atoms excluding the substituent) is preferably 6 to 20, and more preferably 6 to 12.

[0019] Examples of the aralkyl group for the substituent P include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, a phenylpentyl group, and a naphthylmethyl group. The aralkyl group may have a substituent, and examples of the substituent that the aralkyl group has include an alkyl group, an alkoxy group, a halogeno group, a halogenoalkyl group, a cyano group, a nitro group, a thiocyanate group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfo group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, and a sulfamoyl group. The number of carbon atoms in the aralkyl group (the number of carbon atoms excluding the substituent) is preferably 7 to 25, and more preferably 7 to 15.

[0020] For specific examples of the aryl group contained in the aryloxy group, arylthio group, aryloxycarbonyl group, arylsulfonyl group, and arylsulfinyl group of the substituent P, see the above description of the aryl group.

[0021] Examples of heteroaryl groups for the substituent P include a thienyl group, a thiopyranyl group, an isothiochromenyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a pyridyl group, a pyraridinyl group, a pyrimidinyl group, a pyridazinyl group, a thiazolyl group, an isothiazolyl group, a furanyl group, and a pyranyl group. The heteroaryl group may have a substituent, and examples of the substituent that the heteroaryl group has include an alkyl group, an alkoxy group, an aryl group, a halogeno group, a halogenoalkyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a thiocyanate group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfo group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, and a sulfamoyl group. The number of carbon atoms in the heteroaryl group (the number of carbon atoms excluding the substituent) is preferably 2 to 20, and more preferably 3 to 15.

[0022] The amino group of the substituent P is a group represented by the formula: -NR ａ１ R ａ２ and R ａ１ and R ａ２ are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a heteroaryl group. Specific examples of the alkyl group, the aryl group, the aralkyl group, and the heteroaryl group are described above, and examples of the alkenyl group and the alkynyl group include the alkyl groups exemplified above in which some of the carbon-carbon single bonds have been replaced with double bonds or triple bonds. ａ１ and R ａ２ may be linked to each other to form a ring. ａ１ and R ａ２ The number of ring members in the ring formed by linking the groups is preferably 5 or 6, and the constituent atoms of the ring, other than the nitrogen atom, are preferably carbon atoms, oxygen atoms, and sulfur atoms.

[0023] The amide group of the substituent P is an amide group represented by the formula: -NH-C(=O)-R ａ３ and R ａ３is an alkyl group, an aryl group, an aralkyl group, a heteroaryl group, etc. For specific examples of the alkyl group, the aryl group, the aralkyl group, and the heteroaryl group, see the explanations for these groups above.

[0024] The sulfonamide group of the substituent P is a group represented by the formula: -NH-SO ２ -R ａ４ and R ａ４ is an alkyl group, an aryl group, an aralkyl group, a heteroaryl group, etc. For specific examples of the alkyl group, the aryl group, the aralkyl group, and the heteroaryl group, see the explanations for these groups above.

[0025] The substituent P is preferably a halogeno group, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or an amino group, and more preferably a halogeno group, an alkyl group, an aryl group, or an amino group. In this case, the alkyl group or the alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms, the aryl group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms. The amino group is represented by the formula: -NR ａ１ R ａ２ and R ａ１ and R ａ２ are each independently a hydrogen atom, an alkyl group, or an aryl group, the alkyl group preferably having 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and the aryl group preferably having 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms.

[0026] When the substituents P of the methine groups are bonded to each other, it is preferable that the substituents bonded to the two adjacent methine groups are bonded to each other to form a ring. ７１ and R ７３ , R ７２ and R ７４ , R ７３ and R ７５ , R ７４ and R ７６ , R ７５ and R ７７ , R ７６ and R ７８ or R ７７and R ７９ are preferably linked to each other to form a ring.

[0027] The ring formed by mutually linking the substituents P possessed by the methine groups is preferably a 5- to 8-membered ring, more preferably a 5- to 7-membered ring, and even more preferably a 5- or 6-membered ring. The ring formed by mutually linking the substituents P possessed by the methine groups is formed by partially sharing with the methine chain, but may or may not have an unsaturated bond other than the part shared with the methine chain. Preferably, the ring formed by mutually linking the substituents P possessed by the methine groups does not have an unsaturated bond other than the part shared with the methine chain.

[0028] The ring formed by linking the substituents P of the methine groups together may have a substituent, and examples of such a substituent include an organic group and a polar functional group. For details of the organic group, see the explanation of the organic group of the substituent P above. Examples of the polar functional group include a halogeno group, a hydroxyl group, a nitro group, a sulfo group (sulfonic acid group), etc., with a halogeno group being preferred. Among these, the substituents on the ring formed by linking the substituents P together are preferably a halogeno group, an alkyl group, an alkoxy group, an aryl group, or an amino group. In this case, the alkyl group and alkoxy group preferably have 1 to 5 carbon atoms, more preferably 1 to 3, and even more preferably 1 or 2, and the aryl group preferably has 6 to 12 carbon atoms.

[0029] The substituent P that the methine group may have is preferably bonded to the methine group at the meso position (center) or the adjacent methine group, and other methine groups preferably have no substituent. ７１ ~R ７３ may be a hydrogen atom, an organic group, or a polar functional group. ７２ ~R ７４ may be a hydrogen atom, an organic group, or a polar functional group, and R ７１ and R ７５ is preferably a hydrogen atom. ７３ ~R ７５ may be a hydrogen atom, an organic group, or a polar functional group, and R ７１ , R ７２ , R ７６, R ７７ is preferably a hydrogen atom. ７４ ~R ７６ may be a hydrogen atom, an organic group, or a polar functional group, and R ７１ ~R ７３ , R ７７ ~R ７９ is preferably a hydrogen atom. More preferably, the substituents that do not link to form a ring are bonded to the methine group at the meso position, and the substituents that link to form a ring are bonded to the methine group next to the meso position, so that they are linked to each other. It is also preferred that the methine chain L has no substituent.

[0030] In formula (1), A ＋ and A represents a group bonded to the methine chain L. The cyanine compound represented by formula (1) can be obtained by bonding the methine chain L to A. ＋ and A, and the π electron system preferably extends from A ＋ and A is preferably a group that forms such a π electron system. ＋ Preferred examples of A include groups represented by the following formulae (2) to (7).

[0031]

[0032] In formula (2), R １１ represents an organic group, R １２ ~R １７ each independently represents a hydrogen atom, a halogen atom or an organic group, and * represents the bonding site with the methine chain L in formula (1).

[0033]

[0034] In formula (3), R ２１ represents an organic group; ring S represents a hydrocarbon ring having a fused ring structure which may have a substituent, or a heterocycle having a fused ring structure which may have a substituent, and is spiro-bonded to the adjacent pyrrole ring; ring T represents an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, or a fused ring containing any of these ring structures which may have a substituent; and * represents the bonding site to the methine chain L in formula (1).

[0035]

[0036] In formula (4), R ３１ represents an organic group, R ３２ ~R ３５ each independently represents a hydrogen atom, a halogen atom, or an organic group, or R ３２ and R ３３ , R ３３ and R ３４ , R ３４ and R ３５ may be linked to each other to form a ring, and Y １ represents an oxygen atom, a sulfur atom, CH═CH, or CR ３６ R ３７ represents R ３６ and R ３７ represents an organic group, and * represents the bonding site with the methine chain L in formula (1).

[0037]

[0038] In formula (5), R ４１ ~R ４４ each independently represents a hydrogen atom, a halogen atom, or an organic group, or R ４１ and R ４２ , R ４３ and R ４４ may be linked to each other to form a ring, and Y ２ is an oxygen atom, a sulfur atom, or NR ４５ represents R ４５ represents an organic group, and * represents the bonding site with the methine chain L in formula (1).

[0039]

[0040] In formula (6), R ５１ ~R ５４ each independently represents a hydrogen atom, a halogen atom, or an organic group; Y ３ is an oxygen atom, a sulfur atom, or NR ５５ represents R ５５ represents an organic group, and * represents the bonding site with the methine chain L in formula (1).

[0041]

[0042] In formula (7), R ６１ ~R ６３ , R ６５~R ６７ each independently represents a hydrogen atom, a halogen atom, or an organic group; R ６４ represents an organic group, and * represents the bonding site with the methine chain L in formula (1).

[0043] In formulas (2) to (7), R １２ ~R １７ , R ３２ ~R ３５ , R ４１ ~R ４４ , R ５１ ~R ５４ , R ６１ ~R ６３ , R ６５ ~R ６７ Examples of the halogen atom (halogeno group) in R include a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), and an iodine atom (iodo group). １１ ~R １７ , R ２１ , R ３１ ~R ３５ , R ４１ ~R ４４ , R ５１ ~R ５５ , R ６１ ~R ６７ For details of the organic group, the description of the organic group of the substituent P is referred to.

[0044] In formula (2), R １１ R is preferably an alkyl group, an aryl group, or an aralkyl group, and more preferably an alkyl group. Examples of the alkyl group include linear or branched alkyl groups, and more preferably a linear alkyl group. １１ The alkyl group preferably has 3 or more carbon atoms, more preferably 4 or more carbon atoms, and preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less carbon atoms.

[0045] In formula (2), R １２ ~R １７is preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an amino group, more preferably a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and even more preferably a hydrogen atom, an alkyl group, or an alkoxy group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3 carbon atoms, the aryl group or aryloxy group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0046] In formula (3), R ２１ R is preferably an alkyl group, an aryl group, or an aralkyl group, and more preferably an alkyl group. Examples of the alkyl group include linear or branched alkyl groups, and more preferably a linear alkyl group. ２１ The alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms, and is particularly preferably a methyl group or an ethyl group.

[0047] In formula (3), ring S represents a hydrocarbon ring having a fused ring structure or a heterocycle having a fused ring structure. The hydrocarbon ring and heterocycle of ring S may or may not have aromaticity. The number of ring members of ring S is not particularly limited, but the number of ring members of the hydrocarbon ring or heterocycle spiro-bonded to the adjacent pyrrole ring is preferably 5 to 8, more preferably 5 to 7, and even more preferably 5 or 6. Examples of the hydrocarbon ring having a fused ring structure or the heterocycle having a fused ring structure of ring S include an indene ring, a naphthalene ring, an anthracene ring, a fluorene ring, a benzofluorene ring, an indole ring, an isoindole ring, a benzimidazole ring, a quinoline ring, a benzopyran ring, an acridine ring, a xanthene ring, a carbazole ring, a purine ring, and a pteridine ring.

[0048] Group A represented by formula (3) ＋In a cyanine compound having the group A, the ring S is spiro-bonded to the adjacent pyrrole ring, resulting in a twisted bond between the ring S and the pyrrole ring. This results in molecular distortion in the cyanine compound, which affects the band gap and can shift the absorption wavelength to longer wavelengths. Furthermore, association and aggregation of the cyanine compound are suppressed, improving its solubility in organic solvents and resins.

[0049] The hydrocarbon ring or heterocyclic ring of ring S may have a substituent, and examples of such a substituent include an organic group and a polar functional group. For details of these organic groups and polar functional groups, see the explanation of the organic group of the substituent P and the polar functional group described above. As the substituent that ring S may have, an alkyl group, an alkoxy group, an alkylthio group, an alkoxycarbonyl group, an aryl group, an aryloxycarbonyl group, or a halogeno group is preferred, an alkyl group, an alkoxy group, an alkylthio group, a halogeno group, or an aryl group is preferred, and an alkyl group, an alkoxy group, or a halogeno group is more preferred.

[0050] It is preferable that ring S has a π bond, and specifically, it is preferable that the hydrocarbon ring or heterocycle spiro-bonded to the pyrrole ring has a π bond. This makes it easier for the entire ring S to assume a twisted configuration with respect to the pyrrole ring, thereby increasing the molecular distortion of the cyanine compound. In this case, it is preferable that the atom one adjacent to the carbon atom spiro-bonded to the pyrrole ring and the atom two adjacent thereto are connected by a π bond. Examples of the π bond include a double bond, such as a double bond between carbon atoms, a double bond between carbon atoms and nitrogen atoms, and a double bond between nitrogen atoms and nitrogen atoms. The π bond of the hydrocarbon ring or heterocycle spiro-bonded to the adjacent pyrrole ring of ring S may share a portion with the fused ring.

[0051] In the ring S, the fused ring is preferably formed so as to share a bond between the atom one adjacent to the carbon atom spiro-bonded to the pyrrole ring and the atom two adjacent thereto, whereby the ring S is formed bulkily in a twisted state with respect to the pyrrole ring, thereby increasing the molecular distortion of the cyanine compound.

[0052] Ring S is particularly preferably a hydrocarbon ring having a fused ring structure or a heterocyclic ring having a fused ring structure represented by the following formulas (8-1) to (8-4): １ ~Kan U ６ each independently represents a hydrocarbon ring which may have a substituent; Y １１ is -CH ２ represents -, -NH-, -O- or -S-; Y １２ ~Y １６ are each independently —CH ２ Ring U represents -, -CH=, -NH-, -N=, -O- or -S-, and * represents the site of spiro bonding with the adjacent pyrrole ring. １ ~Kan U ６ For the substituents which may be possessed by the ring S, the above description of the substituents which may be possessed by the ring S is referred to.

[0053]

[0054] Ring U １ ~Kan U ６ Examples of the hydrocarbon ring include an aromatic hydrocarbon ring and an aliphatic hydrocarbon ring. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, and a fluoranthene ring. The aromatic hydrocarbon ring may have only one ring structure, or may be one in which two or more ring structures are condensed. Examples of the aliphatic hydrocarbon ring include monocyclic cycloalkanes having 3 to 10 carbon atoms such as cyclopentane, cyclohexane, and cycloheptane; and monocyclic cycloalkenes having 3 to 10 carbon atoms such as cyclopentene, cyclopentadiene, cyclohexene, cyclohexadiene (for example, 1,3-cyclohexadiene), cycloheptene, and cycloheptadiene. Ring U １ ~Kan U ６ is preferably a monocyclic ring, specifically a monocyclic cycloalkene or benzene ring having 3 to 10 carbon atoms (preferably 5 to 8 carbon atoms), and more preferably a benzene ring (specifically a benzene ring fused with a 5- or 6-membered ring spiro-bonded at the * position).

[0055] In formula (3), ring T represents an aromatic hydrocarbon ring, an aromatic heterocycle, or a fused ring containing any of these ring structures, and these ring structures may have a substituent. By having ring T, the cyanine compound has a π-electron system that extends over a wide range from the methine chain L to ring T via the pyrrole ring, thereby enabling the absorption wavelength to be shifted to a longer wavelength.

[0056] The aromatic hydrocarbon ring of ring T is not particularly limited as long as it is composed of carbon atoms and hydrogen atoms and has an aromatic ring structure, and examples thereof include a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, and a fluoranthene ring. The aromatic hydrocarbon ring may have only one ring structure, or two or more ring structures fused together. The aromatic heterocycle of ring T is not particularly limited as long as it contains one or more atoms selected from N (nitrogen atom), O (oxygen atom), and S (sulfur atom) in the ring structure and has aromaticity, and examples thereof include a furan ring, a thiophene ring, a pyrrole ring, a pyrazole ring, an oxazole ring, a thiazole ring, an imidazole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a purine ring, and a pteridine ring. The aromatic heterocycle may have only one ring structure, or two or more ring structures fused together. The fused ring containing these ring structures has a structure in which an aromatic hydrocarbon ring and an aromatic heterocycle are fused together, and examples thereof include an indole ring, an isoindole ring, a benzimidazole ring, a quinoline ring, a benzopyran ring, an acridine ring, a xanthene ring, and a carbazole ring.

[0057] Ring T may have a substituent, and examples of such a substituent include an organic group and a polar functional group. For details of these organic groups and polar functional groups, see the explanations of the organic group of the substituent P and the polar functional group above. Preferred substituents that Ring T may have include alkyl groups, alkoxy groups, alkylthio groups, alkoxycarbonyl groups, aryl groups, aryloxycarbonyl groups, amino groups, cyano groups, halogeno groups, and nitro groups, and are more preferred than alkyl groups, alkoxy groups, alkylthio groups, halogeno groups, and aryl groups. When Ring T has a substituent, the number of substituents is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 to 2. When Ring T has multiple substituents, the multiple substituents may be the same or different. Ring T may not have a substituent.

[0058] The number of π electrons contained in ring T, i.e., the number of π electrons contained in the above-mentioned aromatic hydrocarbon ring, aromatic heterocycle, or fused ring containing these ring structures, is not particularly limited and may be, for example, 4 or more, or 6 or more. There is no particular upper limit on the number of π electrons contained in ring T, but it is preferably 18 or less, more preferably 14 or less, and even more preferably 10 or less. The number of π electrons contained in ring T includes the π electrons of the carbon-carbon bond shared by ring T and the pyrrole ring. From the viewpoint of ease of production of the cyanine compound, ring T is preferably an aromatic hydrocarbon ring, and particularly preferably a benzene ring or a naphthalene ring.

[0059] In formula (4), R ３１ R is preferably an alkyl group, an aryl group, or an aralkyl group, and more preferably an alkyl group. Examples of the alkyl group include linear or branched alkyl groups, and more preferably a linear alkyl group. １１ The alkyl group preferably has 3 or more carbon atoms, more preferably 4 or more carbon atoms, and preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less carbon atoms.

[0060] In formula (4), R ３２ ~R ３５ is an independent group, R ３２ ~R ３５are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an amino group, more preferably a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and even more preferably a hydrogen atom, an alkyl group, or an alkoxy group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3 carbon atoms, the aryl group or aryloxy group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0061] In formula (4), R ３２ and R ３３ , R ３３ and R ３４ , R ３４ and R ３５ Examples of each ring formed by linking the R's together (hereinafter referred to as "ring R") include hydrocarbon rings and heterocyclic rings, and these ring structures may or may not have aromaticity. Examples of ring R include aromatic hydrocarbon rings, aromatic heterocyclic rings, non-aromatic hydrocarbon rings, and non-aromatic heterocyclic rings. The number of ring members in ring R is preferably 5 to 8, more preferably 5 to 7, and even more preferably 5 or 6.

[0062] For the aromatic hydrocarbon and aromatic heterocycle of ring R, see the description of ring T above. Examples of non-aromatic hydrocarbon rings of ring R include aliphatic hydrocarbon rings, such as monocyclic cycloalkanes having 3 to 10 carbon atoms, such as cyclopentane, cyclohexane, and cycloheptane; and monocyclic cycloalkenes having 3 to 10 carbon atoms, such as cyclopentene, cyclopentadiene, cyclohexene, cyclohexadiene (for example, 1,3-cyclohexadiene), cycloheptene, and cycloheptadiene. Examples of non-aromatic heterocycles of ring R include rings in which one or more carbon atoms constituting the above-mentioned aliphatic hydrocarbon rings are substituted with at least one atom selected from N (nitrogen atom), S (sulfur atom), and O (oxygen atom). Examples of non-aromatic heterocycles include a pyrrolidine ring, a tetrahydrofuran ring, a tetrahydrothiophene ring, a piperidine ring, a tetrahydropyran ring, a tetrahydrothiopyran ring, a morpholine ring, a hexamethyleneimine ring, a hexamethylene oxide ring, a hexamethylene sulfide ring, a heptamethyleneimine ring, etc. Ring R may have a fused ring structure fused with another ring, and examples of such ring structures include an indene ring, a fluorene ring, a benzofluorene ring, an indole ring, an isoindole ring, a benzimidazole ring, a quinoline ring, a benzopyran ring, an acridine ring, a xanthene ring, a carbazole ring, a purine ring, a pteridine ring, etc.

[0063] The ring R may have a substituent, and examples of the substituent include an organic group and a polar functional group. For details of these organic groups and polar functional groups, see the explanations of the organic group of the substituent P and the polar functional group above. The polar functional group is preferably a halogeno group. When the ring R has multiple substituents, the multiple substituents may be the same or different. The ring R may not have a substituent.

[0064] In formula (4), Y １ represents CH=CH, the group A ＋ and group A has a quinoline skeleton. １ is CR ３６ R ３７ When R represents ３６ and R ３７For details of the organic group, see the description of the organic group of the substituent P above. ３６ and R ３７ are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or an amino group, and more preferably a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and even more preferably 1 to 3 carbon atoms, the aryl group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0065] In formula (5), R ４１ ~R ４４ is an independent group, R ４１ ~R ４４ are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an amino group, more preferably a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and even more preferably a hydrogen atom, an alkyl group, or an alkoxy group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3 carbon atoms, the aryl group or aryloxy group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0066] In formula (5), R ４１ and R ４２ , R ４３ and R ４４ When they are linked to each other to form a ring, the above description of the ring R applies to each ring.

[0067] In formula (5), Y ２ NR ４５ When R represents ４５ For details of the organic group, see the description of the organic group of the substituent P above. ４５is preferably a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and more preferably a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and even more preferably 1 to 3 carbon atoms. The aryl group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms. The aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0068] In formula (6), R ５１ ~R ５４ is an independent group, R ５１ ~R ５４ are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an amino group, more preferably a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and even more preferably a hydrogen atom, an alkyl group, or an alkoxy group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3 carbon atoms, the aryl group or aryloxy group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0069] In formula (6), Y ３ NR ５５ When R represents ５５ For details of the organic group, see the description of the organic group of the substituent P above. ５５ is preferably a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and more preferably a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and even more preferably 1 to 3 carbon atoms. The aryl group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms. The aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0070] In formula (7), R ６１ ~R ６７ is an independent group, R ６１ ~R ６７are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an amino group, more preferably a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and even more preferably a hydrogen atom, an alkyl group, or an alkoxy group. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3 carbon atoms, the aryl group or aryloxy group preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and the aralkyl group preferably has 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms.

[0071] In formula (1), X － represents a monovalent anion whose conjugate acid has a pKa of −8.0 or less. In the cyanine compound of the present invention, a cation having a cyanine skeleton forms a salt with a monovalent anion whose conjugate acid has a pKa of −8.0 or less. This can increase the solubility of the cyanine compound in resins.

[0072] Examples of acids having a pKa of -8.0 or less include acids having a pKa of -8.0 or less described in Table 1 of Agnes Kutt et al., "Equilibrium Acidities of Super acids", J. Org. Chem., 76, 391-395 (2011). When the pKa is publicly known from literature or the like, the value is cited, and when it is not publicly known, a calculated value obtained using Advanced Chemistry Development (ACD / Labs) Software can be used. － The pKa of the conjugate acid of the anion of X is preferably −10.0 or less, more preferably −11.0 or less, and even more preferably −18.0 or less. － The anion is preferably a weakly nucleophilic anion, and is preferably an anion formed by dissociating a proton from an acid having a low pKa, generally called a super acid.

[0073] X － Examples of the anion include anions represented by the following formulas (9-1) to (9-3). ８１ ~R ８７each independently represents a fluorine atom, a fluoroalkyl group, a fluoroaryl group, or a cyano group; R ８８ and R ８９ each independently represents a fluorine atom, a fluoroalkyl group, a fluoroaryl group, a cyano group, or —SO ２ -R ９０ represents R ９０ represents a fluorine atom, a fluoroalkyl group, a fluoroaryl group, or a cyano group.

[0074]

[0075] X － The anion may be a perchlorate ion, a fluorosulfonate ion, a fluoroalkylsulfonate ion, a cyanoalkylsulfonate ion, a 2,4,6-trinitrobenzenesulfonate ion, a 1,1,3,3-tetracyanoallyl ion, a fluorophosphate ion, a fluoroantimonate ion, or the like, in addition to the anions of formulae (9-1) to (9-3).

[0076] In formulas (9-1) to (9-3), R ８１ ~R ９０ The fluoroalkyl group in R may be linear, branched, or cyclic, preferably linear or branched, and more preferably linear. The fluoroalkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, and is preferably a perfluoroalkyl group. ８１ ~R ９０ The number of carbon atoms in the fluoroaryl group is preferably 6 to 12, more preferably 6 to 10, and is preferably a perfluoroaryl group. Furthermore, the fluoroalkylsulfonate ion, fluorophosphate ion, and fluoroantimonate ion listed above as anions other than the anions of formulas (9-1) to (9-3) are preferably perfluoroalkylsulfonate ion, hexafluorophosphate ion, and hexafluoroantimonate ion, respectively. The number of carbon atoms in the alkyl group of the fluoroalkylsulfonate ion is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 4.

[0077] X － The anion of R is preferably an anion represented by formula (9-1), i.e., a borate ion, which can further increase the solubility of the cyanine compound in the resin. ８１ ~R ８４ is more preferably a fluoroalkyl group, a fluoroaryl group, or a cyano group, even more preferably a fluoroalkyl group or a fluoroaryl group, and particularly preferably a fluoroaryl group. An example of a borate ion having a fluoroaryl group and a conjugate acid with a pKa of −8.0 or less is tetrakis(pentafluorophenyl)borate anion (the conjugate acid has a pKa of approximately −30).

[0078] The cyanine compound used in the present invention preferably has an average transmittance of 81% or more in the wavelength range of 380 nm to 780 nm when the transmittance at the absorption maximum wavelength is 10% in the wavelength range of 300 nm to 1300 nm. This allows the cyanine compound to transmit light in the visible light region with high transmittance, and the laser welding material is substantially free from coloration derived from the cyanine compound. The average transmittance of the cyanine compound in the wavelength range of 380 nm to 780 nm is more preferably 85% or more, and even more preferably 88% or more.

[0079] The cyanine compound preferably has an absorption maximum wavelength in the wavelength range of 750 nm to 1300 nm. Specifically, the cyanine compound preferably has an absorption peak in the wavelength range of 750 nm to 1300 nm in its absorption spectrum in the wavelength range of 600 nm to 1300 nm, and the absorption maximum of the absorption peak preferably reaches its maximum value in the wavelength range of 600 nm to 1300 nm. The absorption maximum wavelength of the cyanine compound may be 780 nm or more, 800 nm or more, 850 nm or more, 900 nm or more, or 1000 nm or more, or may be 1280 nm or less, 1200 nm or less, 1150 nm or less, or 1100 nm or less.

[0080] The cyanine compound preferably has an absorption peak with a half-width of 40 nm or more, more preferably 45 nm or more, and even more preferably 50 nm or more, which allows it to absorb laser light over a wide wavelength range and allows various laser lights to be used in laser welding. On the other hand, the cyanine compound preferably has an absorption peak with a half-width of 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less, which makes it easy to increase the transmittance of light in the visible light region.

[0081] The absorption spectrum of the cyanine compound described above refers to the absorption spectrum of the cyanine compound in chloroform. The half-width refers to the width of the absorption peak at a transmittance of 50% when the transmittance of the absorption maximum wavelength is 10%.

[0082] The resin used in the laser welding material is not particularly limited as long as it melts when irradiated with laser light and can weld together components, but a thermoplastic resin is preferable. This makes it easier for the resin in the laser welding material to melt when irradiated with laser light and weld together components. The resin may be not only one that has undergone complete polymerization, but also a resin raw material (including a resin precursor, raw materials for the precursor, a monomer that constitutes the resin, etc.) that undergoes a polymerization reaction or a crosslinking reaction during use and is incorporated into the resin.

[0083] Examples of resins used in laser welding materials include (meth)acrylic resins, (meth)acrylic urethane resins, polyacrylic acid and its salts, polyacrylamide, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinylpyrrolidone, polyolefin resins (e.g., polyethylene resins, polypropylene resins), cycloolefin resins, polyethyleneimine, melamine resins, polyurethane resins, polystyrene resins, polyvinyl acetate, polyamide resins (e.g., nylon), aramid resins, polyimide resins, polyamideimide resins, alkyd resins, phenolic resins, epoxy resins, polyester resins (e.g., polybutylene terephthalate (PBT) resins, polyethylene terephthalate (PET) resins, polyarylate resins, etc.), polysulfone resins, polyethersulfone resins, polysulfonamides and their salts, butyral resins, polycarbonate resins, and the like. Examples of the resin include carbonate resin, polyacetal resin, polyether resin, polyphenylene sulfide resin, ABS resin (acrylonitrile butadiene styrene resin), AS resin (acrylonitrile-styrene copolymer), styrene-maleic anhydride copolymer, silicone resin, modified silicone resin (e.g., (meth)acrylic silicone resin, alkyl polysiloxane resin, silicone urethane resin, silicone polyester resin, silicone acrylic resin, etc.), fluorine resin (e.g., fluorinated aromatic polymer, polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorine resin (PFA), fluorinated polyaryl ether ketone (FPEK), fluorinated polyimide (FPI), fluorinated polyamic acid (FPAA), fluorinated polyether nitrile (FPEN)), carboxymethyl cellulose, polyethylene glycol, etc. Among these, polyimide resin, polyamideimide resin, (meth)acrylic resin, cycloolefin resin, epoxy resin, polyester resin, polyarylate resin, polyamide resin, polycarbonate resin, polysulfone resin, and fluorinated aromatic polymer are preferred. These resins have high transparency, and when members are welded together using the laser welding material, the welded body can have a good appearance.

[0084] Polyimide resins are polymers containing imide bonds in the repeating units of the main chain, and can be produced, for example, by condensation polymerization of tetracarboxylic dianhydride and diamine to obtain polyamic acid, which is then dehydrated and cyclized (imidized). As the polyimide resin, aromatic polyimides in which aromatic rings are linked by imide bonds are preferably used. Examples of polyimide resins that can be used include Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc., Kapton (registered trademark) manufactured by DuPont, Aurum (registered trademark) manufactured by Mitsui Chemicals, Inc., Merdin (registered trademark) manufactured by Saint-Gobain, and TPS (registered trademark) TI3000 series manufactured by Toray Plastics Precision Co., Ltd.

[0085] The polyamide-imide resin is a polymer containing an amide bond and an imide bond in the repeating unit of the main chain. Examples of the polyamide-imide resin include Torlon (registered trademark) manufactured by Solvay Advanced Polymers, Viromax (registered trademark) manufactured by Toyobo Co., Ltd., and TPS (registered trademark) TI5000 series manufactured by Toray Plastics Seiko Co., Ltd.

[0086] The (meth)acrylic resin is a polymer having a repeating unit derived from (meth)acrylic acid or its derivative, and for example, a resin having a repeating unit derived from a (meth)acrylic acid ester, such as a poly(meth)acrylic acid ester resin, is preferably used. The (meth)acrylic resin is also preferably one having a ring structure in the main chain, and examples thereof include carbonyl group-containing ring structures such as lactone ring structures, glutaric anhydride structures, glutarimide structures, maleic anhydride structures, and maleimide ring structures; and carbonyl group-free ring structures such as oxetane ring structures, azetidine ring structures, tetrahydrofuran ring structures, pyrrolidine ring structures, tetrahydropyran ring structures, and piperidine ring structures. The carbonyl group-containing ring structures also include structures containing carbonyl group derivative groups such as imide groups. Examples of (meth)acrylic resins having a carbonyl group-containing ring structure that can be used include those described in JP-A Nos. 2004-168882, 2008-179677, WO 2005 / 54311, and 2007-31537.

[0087] The cycloolefin resin is a polymer obtained by polymerizing a cycloolefin as at least a part of a monomer component, and is not particularly limited as long as it has an alicyclic structure in a part of the main chain. Examples of the cycloolefin resin include Topas (registered trademark) manufactured by Polyplastics Co., Ltd., Apel (registered trademark) manufactured by Mitsui Chemicals, Inc., Zeonex (registered trademark) and Zeonor (registered trademark) manufactured by Nippon Zeon Co., Ltd., and Arton (registered trademark) manufactured by JSR Corporation.

[0088] Epoxy resins are resins that can be cured by crosslinking an epoxy compound (prepolymer) in the presence of a curing agent or curing catalyst. Examples of epoxy compounds include aromatic epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, and hydrogenated epoxy compounds. Examples of such epoxy compounds include fluorene epoxy (Oxol (registered trademark) PG-100) manufactured by Osaka Gas Chemicals Co., Ltd., bisphenol A epoxy compound (JER (registered trademark) 828EL) and hydrogenated bisphenol A epoxy compound (JER (registered trademark) YX8000) manufactured by Mitsubishi Chemical Corporation, and an alicyclic liquid epoxy compound (Celloxide (registered trademark) 2021P) manufactured by Daicel Corporation.

[0089] The polyester resin is a polymer containing an ester bond in the repeating unit of the main chain, and can be obtained by, for example, condensation polymerization of a polycarboxylic acid (dicarboxylic acid) and a polyalcohol (diol). Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate. Examples of the polyester resin include the OKP series manufactured by Osaka Gas Chemicals Co., Ltd., the TRN series manufactured by Teijin Limited, Teonex (registered trademark), Rynite (registered trademark) manufactured by DuPont, Novapex (registered trademark) manufactured by Mitsubishi Chemical Corporation, Novaduran (registered trademark) manufactured by Mitsubishi Engineering Plastics Corporation, Lumirror (registered trademark) and Toraycon (registered trademark) manufactured by Toray Industries, Inc., and Elitel (registered trademark) manufactured by Unitika Ltd.

[0090] The polyarylate resin is a polymer obtained by polycondensation of a dihydric phenol compound and a dibasic acid (e.g., an aromatic dicarboxylic acid such as phthalic acid), and has a repeating unit containing an aromatic ring and an ester bond in the repeating unit of the main chain. Examples of the polyarylate resin that can be used include Vectran (registered trademark) manufactured by Kuraray Co., Ltd., and U-Polymer (registered trademark) and Unifiner (registered trademark) manufactured by Unitika Ltd.

[0091] Polyamide resins are polymers containing amide bonds in the repeating units of their main chains, and can be obtained, for example, by condensation polymerization of diamines and dicarboxylic acids. Polyamide resins may have an aliphatic skeleton in their main chains, and nylon, for example, can be used as such an amide resin. Polyamide resins may have an aromatic skeleton, and aramid resins are known as such polyamide resins. Aramid resins are preferably used because of their excellent heat resistance and high mechanical strength, and examples of such aramid resins include Twaron (registered trademark) and Conex (registered trademark) manufactured by Teijin Limited, and Kevlar (registered trademark) and Nomex (registered trademark) manufactured by DuPont.

[0092] Polycarbonate resin is a polymer containing a carbonate group (—O—(C═O)—O—) in the repeating unit of the main chain. Examples of polycarbonate resins that can be used include Panlite (registered trademark) and Multilon (registered trademark) manufactured by Teijin Limited, Iupilon (registered trademark) manufactured by Mitsubishi Engineering Plastics Corporation, Iupizeta (registered trademark), Novarex (registered trademark), and Zanter (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc., SD Polyca (registered trademark) manufactured by Sumika Styron Polycarbonate Co., Ltd., and Toughlon (registered trademark) manufactured by Idemitsu Kosan Co., Ltd.

[0093] Polysulfone resins consist of aromatic rings and sulfonyl groups (-SO ２ The polysulfone resin is a polymer having a repeating unit containing a hydroxyl group (-) and an oxygen atom. Examples of polysulfone resins that can be used include Sumikaexcel (registered trademark) PES3600P and PES4100P manufactured by Sumitomo Chemical Co., Ltd., and UDEL (registered trademark) P-1700 manufactured by Solvay Specialty Polymers.

[0094] The fluorinated aromatic polymer is a polymer having a repeating unit containing an aromatic ring having one or more fluorine atoms and at least one bond selected from the group consisting of an ether bond, a ketone bond, a sulfone bond, an amide bond, an imide bond, and an ester bond, and among these, a polymer essentially containing a repeating unit containing an aromatic ring having one or more fluorine atoms and an ether bond is preferred. As the fluorinated aromatic polymer, for example, those described in JP 2008-181121 A can be used.

[0095] It is also preferable to use a (meth)acrylic resin containing a structural unit having a ring structure in the main chain as the resin. Specifically, it is also preferable to use a (meth)acrylic resin containing a structural unit having a ring structure in the main chain, the ring structure including at least one selected from the group consisting of a lactone ring structure, a glutarimide structure, and a maleimide structure. By using such a (meth)acrylic resin, a laser welding material with excellent transparency can be obtained. In addition, because it has excellent heat resistance, a welded body obtained by welding members together using the laser welding material can maintain stable welding even at high temperatures.

[0096] In the (meth)acrylic resin, when the ring structure contained in the main chain is a lactone ring structure, the number of ring members of the lactone ring structure is not particularly limited, and may be, for example, any of 4 to 8. From the viewpoint of excellent stability of the ring structure, the lactone ring structure is preferably a 5- or 6-membered ring, and more preferably a 6-membered ring.

[0097] An example of a structural unit containing a lactone ring structure is a structure represented by the following formula (10): ９１ , R ９２ and R ９３ each independently represents a hydrogen atom or an organic group.

[0098]

[0099] In the lactone ring structural unit of formula (10), R ９１ , R ９２ and R ９３Examples of the organic group include a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. These groups may have any substituent (for example, a hydroxy group, a carboxyl group, an alkoxy group, an ester group, etc.). In addition, in view of the ease of production of (meth)acrylic resins having a lactone ring structure, R ９１ and R ９３ is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ９２ is preferably an alkyl group having 1 to 6 carbon atoms.

[0100] In the (meth)acrylic resin, when the ring structure contained in the main chain is a glutarimide ring structure, an example of a structural unit containing a glutarimide ring structure is a structure represented by the following formula (11): ９４ and R ９５ each independently represents a hydrogen atom or a methyl group, R ９６ represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms.

[0101]

[0102] In the (meth)acrylic resin, when the ring structure contained in the main chain is a maleimide ring structure, an example of a structural unit containing a maleimide ring structure is a structure represented by the following formula (12). The ring structural unit of the following formula (12) is a structural unit derived from maleimide, and can also be referred to as a structural unit containing a succinimide structure. In the following formula (12), ９７ and R ９８ each independently represents a hydrogen atom or a methyl group, R ９９ represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms.

[0103]

[0104] Examples of the structural unit containing the maleimide ring structure of formula (12) include structural units derived from N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-benzylmaleimide, and the like.

[0105] The (meth)acrylic resin containing a structural unit having a ring structure in the main chain preferably contains a unit derived from a (meth)acrylic acid ester. By introducing a (meth)acrylic acid ester unit, the glass transition temperature and fluidity of the (meth)acrylic resin can be adjusted. The content of the structural unit having a ring structure in the main chain in 100% by mass of the (meth)acrylic resin is, for example, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less. The (meth)acrylic resin containing a structural unit having a ring structure in the main chain may contain a unit derived from a styrene-based monomer.

[0106] The resin may be either transparent to visible light or opaque to visible light, but it is preferable that the resin be highly transparent in order to improve the appearance of the welded body obtained by laser welding components and to broaden the range of applications of laser welding materials. For example, the resin preferably has a total light transmittance of 75% or more at a thickness of 0.1 mm, more preferably 80% or more, and even more preferably 85% or more. The upper limit of the total light transmittance of the resin is not particularly limited, and the total light transmittance may be 100% or less, but may be, for example, 95% or less. The total light transmittance is measured in accordance with JIS K 7105.

[0107] The glass transition temperature (Tg) of the resin is not particularly limited, but from the viewpoint of enhancing the heat resistance of a welded body obtained by welding members together with the laser welding material, it is, for example, preferably 110° C. or higher, more preferably 120° C. or higher, and even more preferably 130° C. or higher. The upper limit of the glass transition temperature of the resin is not particularly limited, but from the viewpoint of facilitating laser welding, it is, for example, preferably 380° C. or lower, more preferably 300° C. or lower, and even more preferably 250° C. or lower.

[0108] The content of the cyanine compound in the laser welding material is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more, based on 100% by mass of the solid content of the laser welding material. This allows the cyanine compound contained in the laser welding material to generate sufficient heat upon irradiation with laser light, making it easier to melt the resin. As a result, it becomes easier to properly weld components together using the laser welding material. Meanwhile, the content of the cyanine compound in the laser welding material is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on 100% by mass of the solid content of the laser welding material. This makes it easier to increase the transparency of the laser welding material. Note that, when the laser welding material contains a solvent, the solid content of the laser welding material refers to the amount of the laser welding material excluding the solvent.

[0109] The laser welding material may contain a solvent. The inclusion of a solvent makes it easier to apply the laser welding material. The solvent may function as a solvent (dispersion medium) for the cyanine compound, or may function as a dispersion medium. Examples of solvents include alcohols such as methanol, ethanol, and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; glycol derivatives (ether compounds, ester compounds, ether ester compounds, etc.) such as PGMEA (2-acetoxy-1-methoxypropane), ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, and ethylene glycol ethyl ether acetate; amides such as N,N-dimethylacetamide and N,N-dimethylformamide; ethyl acetate, propyl acetate, etc. esters such as butyl acetate; pyrrolidones such as N-methyl-pyrrolidone (specifically, 1-methyl-2-pyrrolidone, etc.); aromatic hydrocarbons such as toluene, xylene, 1,2,4-trimethylbenzene, etc.; aliphatic hydrocarbons such as cyclohexane, heptane, etc.; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 4-methyltetrahydropyran, dioxane, diethyl ether, dibutyl ether, etc.; halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, etc.; lactones such as γ-butyrolactone, etc. These solvents may be used alone or in combination of two or more.

[0110] The content of the solvent is, for example, preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on 100% by mass of the laser welding material. The content of the solvent is preferably less than 100% by mass, and more preferably 99% by mass or less. By adjusting the content of the solvent within this range, the handleability of the laser welding material can be easily improved.

[0111] The laser-weldable material may contain two or more cyanine compounds. Furthermore, as long as the desired performance of the laser-weldable material is ensured, it may contain a dye other than a cyanine compound, such as at least one dye selected from a near-infrared absorbing dye, a visible light absorbing dye, and an ultraviolet absorbing dye. The laser-weldable material may also contain various additives, such as a dispersant, a plasticizer, a surfactant, a viscosity modifier, an antifoaming agent, a preservative, and a resistivity modifier, as needed.

[0112] The laser welding material can be produced by mixing a cyanine compound with a resin. It is preferable to mix the resin with a cyanine compound solution in which the cyanine compound is dissolved in a solvent, since this facilitates uniform mixing of the cyanine compound and the resin. It is also preferable to premix the resin with a solvent, and then mix the resulting mixture with the cyanine compound solution to produce the laser welding material.

[0113] In the difference spectrum of transmittance in the wavelength range of 300 nm to 1300 nm between the laser welding material and a resin composition obtained by removing the cyanine compound from the laser welding material, the average transmittance in the wavelength range of 380 nm to 780 nm when the transmittance at the absorption maximum wavelength is 10% is preferably 81% or more. This allows the laser welding material to transmit light in the visible light range with high transmittance, resulting in transparency and excellent invisibility. The average transmittance in the wavelength range of 380 nm to 780 nm in the difference spectrum is more preferably 85% or more, and even more preferably 88% or more.

[0114] The difference spectrum was obtained by measuring the transmission spectrum of the laser weldable material and the transmission spectrum of a resin composition obtained by removing the cyanine compound from the laser weldable material, and then taking the logarithm (log １０ ) and then exponentially converting the difference. Specifically, the transmittance of the difference spectrum can be calculated based on the following formula: Transmittance of the difference spectrum (%) = 10^[log １０ (Transmittance of laser welding material) -log １０ (transmittance of resin composition)]×100.

[0115] The laser weldable material can be used, for example, by coating it on members to be joined by laser welding. Hereinafter, the members to be joined by laser welding and to which the laser weldable material is applied will be referred to as the "substrate." The present invention also provides a laminate having a substrate and a light absorbing layer provided on the substrate and formed from the laser weldable material.

[0116] The substrate may be either laser-transparent or laser-opaque. A coating of a laser welding material is formed on the substrate, and the coating is dried or cured as necessary to form a light-absorbing layer on the substrate. A member to be bonded to the substrate (hereinafter referred to as a "bonding member") is superimposed on the substrate with the light-absorbing layer from the light-absorbing layer side, and laser light is irradiated onto the light-absorbing layer. The cyanine compound contained in the light-absorbing layer absorbs the energy of the laser light, generates heat, melts the resin of the light-absorbing layer, and welds the substrate and the bonding member. In other words, the substrate and the bonding member can be laser-welded by a process of applying the laser welding material to the substrate to form a light-absorbing layer from the laser welding material, and a process of superimposing the bonding member on the substrate with the light-absorbing layer from the light-absorbing layer side, and irradiating the light-absorbing layer with laser light.

[0117] Although the materials of the substrate and the joining member are not particularly limited, the substrate and the joining member are preferably made of a resin, which facilitates more solid welding using the laser welding material. The resin constituting the substrate and the joining member may be the same or different from the resin contained in the laser welding material, but the substrate and the joining member are preferably made of the same resin as the resin contained in the laser welding material, which facilitates more solid bonding between the substrate and the joining member and makes the joint between the substrate and the joining member less noticeable.

[0118] The laser welding material can be applied to a substrate by known coating methods such as spin coating, solvent casting, roll coating, spray coating, bar coating, dip coating, screen printing, flexographic printing, and inkjet printing. The method for applying the laser welding material is not limited to these, and application may be performed using, for example, a pen-type coating tool (a coating tool consisting of a container and a pen core). The thickness of the light-absorbing layer formed from the coating film of the laser welding material is not particularly limited, but is preferably 1 mm or less, more preferably 500 μm or less, even more preferably 300 μm or less, even more preferably 100 μm or less, and preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

[0119] Examples of laser welding machines include Trumpf TruDiode (registered trademark) (laser wavelength: 920-1050 nm), Han's Laser WFD series (laser wavelength: 915 nm), LPKF Laser & Electronics PowerWeld 2600 (laser wavelength: 980 nm), Coherent ExactWeld 230P, Emerson Electric GLX series (laser wavelength: 990 nm) or GL-300 (laser wavelength: 1080 nm), Amada ML-5120 Direct Diode Laser Welder-120W (laser wavelength: 915 nm), IPTE Factory Automation laser welding machine, and EVLASER SRL TITAN. WELD system (laser wavelength: 980 nm), IPG Photonics laser welding machine, Panasonic Industries VL-W1 series (laser wavelength: 1070 nm), Mecco 200W or 300W (laser wavelength: 1064 nm), Hamamatsu Photonics laser heating system L16490-343 or T-SMILS laser heating system L15570 series, Fine Devices FD2330 (laser wavelength: 808 nm, 940 nm, 980 nm), Nippon Avionics semiconductor laser welding machine LW-D30A / LW-D100 (laser wavelength: 980 nm), TOWA Laserfront fiber laser processing machine M720A series, laser resin welding system LS-W100 (laser wavelength: 940 nm) manufactured by Seidensha Electronics Co., Ltd., Galweld type M or type S (laser wavelength: 1070 nm) manufactured by Hiroshima Corporation, etc. can be used.

[0120] The laser light may be irradiated from the substrate side or from the bonding member side. When the laser light is irradiated from the substrate side, a substrate that transmits the laser light is used. In this case, the bonding member may or may not be a material that transmits the laser light. When the laser light is irradiated from the bonding member side, a bonding member that transmits the laser light is used. In this case, the substrate may or may not be a material that transmits the laser light.

[0121] Examples of laser light include solid-state lasers, fiber lasers, semiconductor lasers, gas lasers, and liquid lasers. For example, YAG lasers (wavelengths of 1064 nm and 1070 nm) and semiconductor lasers (wavelengths of 808 nm, 840 nm, 940 nm, and 980 nm) can be preferably used. The wavelength of the laser light is preferably within the range of 800 nm to 1300 nm, more preferably 850 nm to 1200 nm, and even more preferably 900 nm to 1100 nm. Of these, laser light with a wavelength of 940 nm, 980 nm, or 1070 nm is particularly preferred.

[0122] The laser welding material can also be used to form an absorbent material for laser welding. Laser welding is usually performed by overlapping a transparent material that transmits laser light with an absorbent material that absorbs laser light and irradiating the laser light from the transparent material side. However, the laser welding material can also be used as a material to form the absorbent material. The present invention also provides an absorbent material formed from the laser welding material. The absorbent material can be formed by molding the laser welding material into any shape. For example, the absorbent material can be formed by placing the laser welding material in a mold and drying or curing it. Alternatively, a sheet-like absorbent material can be formed by pressing or stretching the laser welding material in a semi-molten state. The absorbent material formed from the laser welding material can be welded to the transparent material by overlapping the transparent material and irradiating the laser light from the transparent material side, or by overlapping the transparent materials with an absorbent material sandwiched between them and irradiating the laser light.

[0123] The shapes of the substrate and absorbent are not particularly limited, and examples include plate-like, sheet-like, granular, powder-like, lumpy, particle aggregate-like, spherical, oval-spherical, lenticular, cubic, columnar, rod-like, conical, cylindrical, needle-like, fibrous, hollow fiber-like, and porous shapes. A sheet-like absorbent is preferred because it can improve the handleability of the absorbent and broaden its range of application. A sheet-like absorbent, i.e., an absorbent sheet, can be used on a substrate with a curved surface, not just a flat substrate. Furthermore, since the absorbent sheet can be formed from a solvent-free laser welding material, it is possible to use a resin material with low solvent resistance, thereby increasing the freedom of resin material selection. The thickness of the absorbent sheet is, for example, preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less.

[0124] In the absorption spectrum of a wavelength range of 600 nm to 1300 nm, the laser welding material, light-absorbing layer, or absorber preferably has an absorption maximum wavelength in the wavelength range of 750 nm to 1300 nm. Specifically, in the absorption spectrum of a wavelength range of 600 nm to 1300 nm, it is preferable that the absorption peak has an absorption maximum in the wavelength range of 750 nm to 1300 nm, and that the absorption maximum of the absorption peak preferably reaches a maximum value in the wavelength range of 600 nm to 1300 nm. If the light-absorbing layer or absorber has an absorption maximum wavelength in such a range, it becomes easier to perform appropriate laser welding with commonly used laser light such as a YAG laser or semiconductor laser. The absorption maximum wavelength of the laser welding material, light-absorbing layer, or absorber may be 780 nm or more, 800 nm or more, 850 nm or more, 900 nm or more, or 1000 nm or more, or 1280 nm or less, 1200 nm or less, 1150 nm or less, or 1100 nm or less.

[0125] The light-absorbing layer preferably has a transmittance of 0% or more and 99% or less at a wavelength of 1070 nm, which is a wavelength that is relatively commonly used in laser light. The transmittance of the light-absorbing layer at a wavelength of 1070 nm may be 1% or more, 2% or more, 3% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more.

[0126] The light-absorbing layer preferably has a transmittance of 0% or more and 99% or less at a maximum absorption wavelength in the wavelength range of 750 nm to 1300 nm. The transmittance of the light-absorbing layer at the maximum absorption wavelength may be 1% or more, 2% or more, 3% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more.

[0127] The light-absorbing layer preferably has an average transmittance of 80% or more in the wavelength range of 380 nm to 780 nm. This allows the light-absorbing layer to transmit light in the visible light range with high transmittance, resulting in transparency and excellent invisibility. This makes it possible to make the bond between the substrate and the bonding member less noticeable, improving the appearance of the welded body formed by welding the substrate and the bonding member. The average transmittance of the light-absorbing layer in the wavelength range of 380 nm to 780 nm may be 83% or more, or even 85% or more. The average transmittance of the light-absorbing layer in the wavelength range of 380 nm to 780 nm is preferably higher than the transmittance at a wavelength of 1070 nm, and is preferably higher than the transmittance at the maximum absorption wavelength in the wavelength range of 750 nm to 1300 nm.

[0128] The absorber formed from the laser welding material preferably has a transmittance of 0% or more and 99% or less at a wavelength of 1070 nm, which is a wavelength that is relatively commonly used in laser light. The transmittance of the absorber at a wavelength of 1070 nm may be 1% or more, 2% or more, 3% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, or may be 98% or less, 97% or less, 95% or less, or 93% or less.

[0129] The absorber formed from the laser welding material preferably has a transmittance of 0% or more and 99% or less at a maximum absorption wavelength in the wavelength range of 750 nm to 1300 nm. The transmittance of the absorber at the maximum absorption wavelength may be 1% or more, 2% or more, 3% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 85% or more, or may be 98% or less, 97% or less, 95% or less, 93% or less, or 90% or less.

[0130] The absorbent formed from the laser welding material may have high transmittance for light in the visible light region, or may have low transmittance for light in the visible light region. The absorbent formed from the laser welding material may have an average transmittance of 70% or more, 73% or more, or 75% or more in the wavelength range of 380 nm to 780 nm. In the absorbent formed from the laser welding material, the average transmittance in the wavelength range of 380 nm to 780 nm is preferably higher than the transmittance at a wavelength of 1070 nm, and is preferably higher than the transmittance at the maximum absorption wavelength in the wavelength range of 750 nm to 1300 nm.

[0131] This application claims the benefit of priority based on Japanese Patent Application No. 2023-197624, filed on November 21, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-197624, filed on November 21, 2023, are incorporated herein by reference.

[0132] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0133] (1) Synthesis of Compounds (1-1) Synthesis Example 1: Synthesis of Cyanine Compound 1 To a 500 mL four-neck flask placed in a water bath, 21.9 g (0.195 mol) of potassium tert-butoxide, 98.1 g of ultra-dehydrated tetrahydrofuran, 10.8 g (0.065 mol) of fluorene, and 11.5 g (0.13 mol) of ethyl acetate were added in this order under a nitrogen flow (10 mL / min) while taking care to avoid heat generation. The mixture was then stirred for 3 hours under reflux conditions while heating in a water bath. The resulting reaction solution was cooled and quenched with dilute hydrochloric acid, extracted with ethyl acetate, and washed three times with brine. The resulting organic phase was dehydrated with magnesium sulfate and concentrated using an evaporator. The resulting solid was then purified by silica gel column chromatography (developing solvent: ethyl acetate) to obtain 12.5 g of 9-acetyl-9H-fluorene.

[0134] A 500 mL separable flask was charged with 6.2 g (0.026 mol) of 9-acetyl-9H-fluorene, 5.0 g (0.026 mol) of 1-phenylhydrazine hydrochloride, and 112.1 g of tert-amyl alcohol as a solvent, and the mixture was reacted at 90°C for 4 hours while stirring under a nitrogen flow (10 mL / min). After completion of the reaction, the reaction solution was cooled to room temperature, quenched with 100 g of water, and extracted with 100 g of ethyl acetate. The resulting organic phase was dehydrated with magnesium sulfate and concentrated using an evaporator. The resulting solid was purified by silica gel column chromatography (developing solvent: chloroform) to obtain 5.1 g of indolenine compound 1.

[0135] Next, 2.0 g (0.007 mol) of the indolenine compound 1 obtained above, 11.2 g (0.079 mol) of iodomethane, and 53.3 g of N,N-dimethylformamide were placed in a 100 mL four-neck flask and stirred at 80° C. for 6 hours under a nitrogen flow (5 mL / min). After cooling to room temperature, the reaction solution was precipitated in 300 g of toluene, and the precipitated solid was separated by filtration to obtain 1.8 g of indolenium salt 1.

[0136]

[0137] Bioconjugate Chemistry, 29 (11), pp. 3886-3895 (2018) according to the method described, N-((1E)-2-phenyl-3-((E)-(phenylimino)methyl)cyclohex-2-en-1-ylidene)methylaniline hydrochloride (dianiline salt 1) was synthesized. In a 100 mL four-neck flask, 1.0 g (0.0021 mol) of the indolenium salt 1 obtained above, 0.42 g (0.0011 mol) of dianiline salt 1, 0.28 g (0.003 mol) of sodium acetate, 9.9 g of acetic acid, and 10.1 g of acetic anhydride were added and stirred at 100 ° C. for 8 hours. The reaction solution was cooled to room temperature, 150 g of water was added, and the precipitated solid was collected by filtration. This solid was purified by silica gel column chromatography (developing solvent: chloroform) to obtain 0.21 g of the iodide salt of cyanine compound 1.

[0138]

[0139] 0.50 g (0.50 mmol) of the iodide salt of cyanine compound 1 was dissolved in 20 mL of acetone, and 6.7 g (0.10 mmol) of a 10.5% aqueous solution of sodium tetrakis(pentafluorophenyl)borate (manufactured by Nippon Shokubai Co., Ltd.) was added, followed by stirring overnight at room temperature. The reaction solution was concentrated using an evaporator and then purified by silica gel column chromatography (developing solvent: chloroform) to obtain 0.57 g of cyanine compound 1 shown in Table 1. The pKa of the tetrakis(pentafluorophenyl)borate anion in cyanine compound 1 was -8.0 or less.

[0140]

[0141] (1-2) Synthesis Example 2: Synthesis of Cyanine Compound 2 Using 3-butyl-2-(2-[3-[2-(3-butyl-1,1-dimethyl-1,3-dihydrobenzo[e]indol-2-ylidene)ethylidene]-2-chloro-cyclohex-1-enyl]vinyl)-1,1-dimethyl-1H-benzo[e]indolium hexafluorophosphate (Few Chemicals, S0712) as the starting cyanine compound, 1.00 g (1.2 mmol) of the starting cyanine compound was dissolved in 100 g of acetone, and 9.00 g (1.4 mmol) of a 10.5% aqueous solution of sodium tetrakis(pentafluorophenyl)borate heated to 40°C was added thereto, followed by stirring at room temperature for 2 hours. Next, the solvent was distilled off, and the resulting solid was washed with ion-exchanged water to obtain 1.47 g of Cyanine Compound 2 shown in Table 1.

[0142] (1-3) Synthesis Example 3: Synthesis of cyanine compound 3

[0123] 1.23 g of cyanine compound 3 shown in Table 1 was obtained in the same manner as in Synthesis Example 2, except that 6-butoxy-2-[5-(6-butoxy-1-butyl-1H-benzo[cd]indol-2-ylidene)-penta-1,3-dienyl]-1-butyl-benzo[cd]indolium tetrafluoroborate (manufactured by Few Chemicals, S2437) was used as the starting cyanine compound.

[0143] (1-4) Synthesis Example 4: Synthesis of cyanine compound 4

[0123] 1.79 g of cyanine compound 4 shown in Table 1 was obtained in the same manner as in Synthesis Example 2, except that 1-butyl-2-(2-[3-(2-[1-butyl-1H-benzo[cd]indol-2-ylidene]ethylidene)-2-chloro-1-cyclohex-1-enyl]-vinyl)-benzo[cd]indolium tetrafluoroborate (IR1014, manufactured by Exciton) was used as the starting cyanine compound.

[0144] (1-5) Synthesis Example 5: Synthesis of cyanine compound 5

[0123] 2.12 g of cyanine compound 5 shown in Table 1 was obtained in the same manner as in Synthesis Example 2, except that 1-butyl-2-(2-[3-(2-[1-butyl-1H-benzo[cd]indol-2-ylidene]ethylidene)-2-phenyl-1-cyclopent-1-enyl]-vinyl)-benzo[cd]indolium tetrafluoroborate (manufactured by Few Chemicals, S0813) was used as the starting cyanine compound.

[0145] (1-6) Synthesis Example 6: Synthesis of cyanine compound 6

[0089] 1.12 g of cyanine compound 6 shown in Table 1 was obtained in the same manner as in Synthesis Example 2, except that 1-butyl-2[7-(1-butyl-1H-benzo[cd]indol-2-ylidene)-hepta-1,3,5-trienyl]-benzo[cd]indolium hexafluorophosphate (manufactured by Few Chemicals, S2058) was used as the starting cyanine compound.

[0146]

[0147] (1-7) Synthesis Example 7: Synthesis of phthalocyanine compound 1 According to the method described in Example 16 of Japanese Patent No. 4278923, phthalocyanine compound 1 shown in Table 2 was synthesized.

[0148] (1-8) Synthesis Example 8: Synthesis of phthalocyanine compound 2 According to the method described in Example 2 of Japanese Patent No. 3260317, phthalocyanine compound 2 shown in Table 2 was synthesized.

[0149]

[0150] (1-9) Synthesis Example 9: Synthesis of acrylic resin A A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen inlet tube was charged with 83.5 parts by mass of methyl methacrylate, 12 parts by mass of 2-hydroxymethyl (meth)acrylate, 88.7 parts by mass of toluene, and 0.05 parts by mass of an antioxidant (ADEKA CORPORATION, Adekastab (registered trademark) 2112), and the temperature was raised to 105°C while nitrogen was passed through the reaction vessel. When refluxing began due to the temperature increase, 0.435 parts by mass of a 20% by weight toluene solution of t-amylperoxyisononanoate (Arkema Yoshitomi Co., Ltd., Luperox (registered trademark) 570T20) was added as a polymerization initiator. Subsequently, 4.5 parts by mass of styrene and 0.15 parts by mass of n-dodecyl mercaptan were added dropwise over 2 hours, and then 0.865 parts by mass of a 20 wt % toluene solution of t-amylperoxyisononanoate was added dropwise over 4 hours. During the dropwise addition, the mixed solution was refluxed at approximately 105°C to 110°C to allow solution polymerization to proceed. After the dropwise addition was completed, the mixture was aged for another 2 hours at the same temperature.

[0151] To the resulting polymer solution, 0.075 parts by mass of stearyl phosphate (Phoslex A-18, manufactured by SC Organic Chemical Industry Co., Ltd.) was added, and a cyclization condensation reaction to form a lactone ring structure was carried out for 2 hours under reflux at approximately 90 to 110°C. The polymer solution was then passed through a multi-tube heat exchanger heated to 240°C to complete the cyclization condensation reaction. The polymer solution was then introduced into a vented twin-screw screw extruder (L / D = 52) at a processing rate of 100 parts by mass / hour (equivalent to the amount of resin). The vented twin-screw screw extruder had a barrel temperature of 250°C, one rear vent, four fore vents (referred to as the first, second, third, and fourth vents from the upstream side), and a side feeder located between the third and fourth vents, and a leaf disc-type polymer filter (filtration accuracy 10 μm) was disposed at the tip. Devolatilization was performed by setting the degree of vacuum at the rear vent to 798 hPa, the degree of vacuum at the first vent to 266 hPa, and the degree of vacuum at the second vent to the fourth vent to 27 hPa. During this process, ion-exchanged water was introduced from behind the second vent, the third vent, and the fourth vent at an introduction rate of 1.5 parts by mass / hour.

[0152] After devolatilization was completed, the molten resin composition remaining in the extruder was discharged from the tip of the extruder while being filtered through a polymer filter. The resin composition was then passed through a die attached to the tip of the extruder and introduced into a water tank filled with cooling water for cooling, yielding strands of the resin composition. The cooling water was filtered through a 1 μm pore size filter (Micropore Filter 1EU, manufactured by Organo Corporation) and maintained at a temperature within the range of 30±10°C. The cooled strands were introduced into a cutter (pelletizer) to obtain pellets of acrylic resin A having a lactone ring structure in the main chain.

[0153] (2) Spectroscopic Measurement of Cyanine Compounds and Phthalocyanine Compounds Chloroform solutions of cyanine compounds 1 to 6 and phthalocyanine compounds 1 and 2 were prepared, and their transmission spectra were measured in the wavelength range of 300 nm to 1300 nm. The concentrations of the chloroform solutions of the cyanine compounds and phthalocyanine compounds were adjusted so that the transmittance at the absorption maximum wavelength was 10% (±0.05%). Using a spectrophotometer (Shimadzu Corporation, UV-3600), the light transmittance was measured at a measurement interval of 1.0 nm. The wavelength at which absorption was maximized in the wavelength range of 300 nm to 1300 nm (maximum absorption wavelength λmax), the peak width at 50% transmittance of the peak corresponding to the maximum absorption wavelength (half-width), and the average visible light transmittance in the wavelength range of 380 nm to 780 nm were determined. The results are shown in Table 3. Cyanine compounds 1 to 6 had an average transmittance of 81% or more in the wavelength range of 380 nm to 780 nm when the transmittance at the absorption maximum wavelength was 10%.

[0154]

[0155] (3) Preparation of Laser Weldable Materials (3-1) Preparation Example 1: Preparation of Laser Weldable Material 1 47.5 parts by mass of chloroform was added to 4.94 parts by mass of polymethyl methacrylate (hereinafter referred to as "PMMA") and stirred at room temperature for 1 hour to obtain resin solution 1. 47.5 parts by mass of chloroform was added to 0.06 parts by mass of cyanine compound 4 and stirred at room temperature for 1 hour to obtain dye solution 1. Resin solution 1 and dye solution 1 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser weldable material 1 with a solute concentration of 5.0%.

[0156] (3-2) Preparation Example 2: Preparation of Laser Welding Material 2 45.0 parts by mass of chloroform was added to 9.52 parts by mass of PMMA, and the mixture was stirred at room temperature for 1 hour to obtain resin solution 2. 45.0 parts by mass of chloroform was added to 0.48 parts by mass of cyanine compound 5, and the mixture was stirred at room temperature for 1 hour to obtain dye solution 2. Resin solution 2 and dye solution 2 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 25N) to remove foreign matter, obtaining laser welding material 2 with a solute concentration of 10.0%.

[0157] (3-3) Preparation Example 3: Preparation of Laser Weldable Material 3 47.5 parts by mass of chloroform was added to 4.94 parts by mass of PMMA, and the mixture was stirred at room temperature for 1 hour to obtain Resin Solution 3. 47.5 parts by mass of chloroform was added to 0.06 parts by mass of Cyanine Compound 5, and the mixture was stirred at room temperature for 1 hour to obtain Dye Solution 3. Resin Solution 3 and Dye Solution 3 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining Laser Weldable Material 3 with a solute concentration of 5.0%.

[0158] (3-4) Preparation Example 4: Preparation of Laser Welding Material 4 48.8 parts by mass of chloroform was added to 2.50 parts by mass of PMMA, and the mixture was stirred at room temperature for 1 hour to obtain resin solution 4. 48.8 parts by mass of chloroform was added to 0.003 parts by mass of cyanine compound 5, and the mixture was stirred at room temperature for 1 hour to obtain dye solution 4. Resin solution 4 and dye solution 4 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 4 with a solute concentration of 2.5%.

[0159] (3-5) Preparation Example 5: Preparation of Laser Welding Material 5 45.0 parts by mass of chloroform was added to 9.52 parts by mass of acrylic resin A and stirred at room temperature for 1 hour to obtain resin solution 5. 45.0 parts by mass of chloroform was added to 0.48 parts by mass of cyanine compound 5 and stirred at room temperature for 1 hour to obtain dye solution 5. Resin solution 5 and dye solution 5 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 25N) to remove foreign matter, obtaining laser welding material 5 with a solute concentration of 10.0%.

[0160] (3-6) Preparation Example 6: Preparation of Laser Welding Material 6 47.5 parts by mass of chloroform was added to 4.94 parts by mass of acrylic resin A, and the mixture was stirred at room temperature for 1 hour to obtain resin solution 6. 47.5 parts by mass of chloroform was added to 0.06 parts by mass of cyanine compound 5, and the mixture was stirred at room temperature for 1 hour to obtain dye solution 6. Resin solution 6 and dye solution 6 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 6 with a solute concentration of 5.0%.

[0161] (3-7) Preparation Example 7: Preparation of Laser Welding Material 7 48.8 parts by mass of chloroform was added to 2.50 parts by mass of acrylic resin A and stirred at room temperature for 1 hour to obtain resin solution 7. 48.8 parts by mass of chloroform was added to 0.003 parts by mass of cyanine compound 5 and stirred at room temperature for 1 hour to obtain dye solution 7. Resin solution 7 and dye solution 7 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 7 with a solute concentration of 2.5%.

[0162] (3-8) Preparation Example 8: Preparation of Laser Welding Material 8 47.5 parts by mass of chloroform was added to 4.94 parts by mass of cycloolefin polymer (hereinafter referred to as "COP") and stirred at room temperature for 1 hour to obtain resin solution 8. 47.5 parts by mass of chloroform was added to 0.06 parts by mass of cyanine compound 5 and stirred at room temperature for 1 hour to obtain dye solution 8. Resin solution 8 and dye solution 8 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 8 with a solute concentration of 5.0%.

[0163] (3-9) Preparation Example 9: Preparation of Laser Welding Material 9 49.4 parts by mass of cyclohexanone was added to 1.25 parts by mass of polycarbonate (hereinafter referred to as "PC"), heated to 75°C, and stirred for 1 hour to obtain resin solution 9. 49.4 parts by mass of cyclohexanone was added to 0.002 parts by mass of cyanine compound 5, and stirred at room temperature for 1 hour to obtain dye solution 9. Resin solution 9 and dye solution 9 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 9 with a solute concentration of 1.25%.

[0164] (3-10) Preparation Example 10: Preparation of Laser Welding Material 10 45.0 parts by mass of chloroform was added to 9.30 parts by mass of PMMA and stirred at room temperature for 1 hour to obtain resin solution 10. 45.0 parts by mass of chloroform was added to 0.48 parts by mass of phthalocyanine compound 1 and stirred at room temperature for 1 hour to obtain dye solution 10. Resin solution 10 and dye solution 10 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 25N) to remove foreign matter, obtaining laser welding material 10 with a solute concentration of 10.0%.

[0165] (3-11) Preparation Example 11: Preparation of Laser Welding Material 11 47.5 parts by mass of chloroform was added to 4.94 parts by mass of PMMA, and the mixture was stirred at room temperature for 1 hour to obtain resin solution 11. 47.5 parts by mass of chloroform was added to 0.06 parts by mass of phthalocyanine compound 2, and the mixture was stirred at room temperature for 1 hour to obtain dye solution 11. Resin solution 11 and dye solution 11 were mixed and stirred at room temperature for 2 hours, and then filtered through a 0.45 μm pore size filter (GL Sciences, non-aqueous 13N) to remove foreign matter, obtaining laser welding material 11 with a solute concentration of 5.0%.

[0166] (3-12) Preparation Example 12: Preparation of laser weldable material 12 0.05 parts by mass of cyanine compound 5 was mixed with PMMA pellets, and the mixture was melt-kneaded for 5 minutes using a Laboplastomill 4C150 manufactured by Toyo Seiki Seisaku-sho, at a screw rotation speed of 150 rpm and a set temperature of 220°C, to obtain a pellet-shaped laser weldable material 12 made of PMMA and cyanine compound 5.

[0167] (3-13) Preparation Example 13: Preparation of laser weldable material 13

[0122] 0.01 parts by mass of cyanine compound 5 was mixed with the pellets of acrylic resin A obtained in Synthesis Example 9, and the mixture was melt-kneaded for 3 minutes using a Laboplastomill 4C150 manufactured by Toyo Seiki Seisaku-sho, Ltd., at a screw rotation speed of 150 rpm and a set temperature of 230°C, to obtain a pellet-shaped laser weldable material 13 made of acrylic resin A and cyanine compound 5.

[0168] (3-14) Preparation Example 14: Preparation of laser weldable material 14

[0123] 0.10 parts by mass of cyanine compound 5 was mixed with the pellets of acrylic resin A obtained in Synthesis Example 9, and the mixture was melt-kneaded for 3 minutes using a Laboplastomill 4C150 manufactured by Toyo Seiki Seisaku-sho, Ltd., at a screw rotation speed of 150 rpm and a set temperature of 240°C, to obtain a pellet-shaped laser weldable material 14 made of acrylic resin A and cyanine compound 5.

[0169] (3-15) Preparation Example 15: Preparation of laser weldable material 15 Pellet-shaped laser weldable material 15 was obtained in the same manner as in Preparation Example 12, except that PMMA in Preparation Example 12 was changed to PC.

[0170] (3-16) Preparation Example 16: Preparation of laser welding material 16 A pellet-shaped laser welding material 16 was obtained in the same manner as in Preparation Example 12, except that PMMA in Preparation Example 12 was changed to polystyrene (hereinafter referred to as “PSt”).

[0171] (3-17) Preparation Example 17: Preparation of laser welding material 17 Pellet-shaped laser welding material 17 was obtained in the same manner as in Preparation Example 12, except that PMMA in Preparation Example 12 was changed to acrylonitrile-styrene copolymer (hereinafter referred to as “AS”).

[0172] (4) Preparation of Resin Substrate for Laser Welding Test (4-1) Production Example 1: Preparation of Resin Substrate A1 A polymethyl methacrylate plate (manufactured by Mitsubishi Chemical Corporation, size 70 mm × 150 mm × 2 mmt, hereinafter referred to as “PMMA plate”) was cut into a size of 37.5 mm × 17 mm using an ultrasonic cutter (manufactured by Suzuki Corporation, SUW-30CT) to obtain a resin substrate A1.

[0173] (4-2) Production Example 2: Preparation of Resin Base Material A2 The pellets of acrylic resin A obtained in Synthesis Example 9 were dried at 100°C for 12 hours or more, and then molded using an injection molding machine (NS40-5A, manufactured by Nissei Resin Co., Ltd.) at a molding temperature of 215°C, a mold temperature of 70°C, and a mold measuring 100 mm x 100 mm x 2 mmt to produce an acrylic plate. This was then cut into a size of 37.5 mm x 17 mm using an ultrasonic cutter (SUW-30CT, manufactured by Suzuki Motor Corporation) to obtain Resin Base Material A2.

[0174] (4-3) Production Example 3: Preparation of resin substrate A3 A cycloolefin polymer plate (manufactured by Zeon Corporation, size 70 mm × 150 mm × 3 mmt, hereinafter referred to as “COP plate”) was cut into a size of 37.5 mm × 17 mm using an ultrasonic cutter (manufactured by Suzuki Corporation, SUW-30CT) to obtain a resin substrate A3.

[0175] (4-4) Production Example 4: Preparation of resin substrate A4 A polycarbonate plate (size 70 mm × 150 mm × 2 mmt, hereinafter referred to as “PC plate”) was cut into a size of 37.5 mm × 17 mm using an ultrasonic cutter (manufactured by Suzuki Corporation, SUW-30CT) to obtain a resin substrate A4.

[0176] (4-5) Production Example 5: Preparation of Resin Substrate B1 The PMMA plate used in Production Example 1 was cut to a size of 70 mm x 50 mm, and 1 cc of laser welding material 1 was dripped onto the PMMA plate. A coating of laser welding material 1 was formed on the PMMA plate using a spin coater (Mikasa Co., Ltd., 1H-D7). The rotation speed of the spin coater was adjusted within a range of 700 rpm to 1600 rpm so that the light absorbing layer formed from the coating had a predetermined transmittance, and the holding time was set to 1 second. The PMMA plate on which the coating of laser welding material 1 was formed was placed in a precision incubator (Yamato Scientific Co., Ltd., DN610I) and heated at 90 ° C. for 30 minutes. The coating of laser welding material 1 was dried to form a light absorbing layer, and a laminate with a light absorbing layer formed on the PMMA plate was produced. This laminate was then cut to a size of 37.5 mm x 17 mm using an ultrasonic cutter to obtain resin substrate B1.

[0177] (4-6) Production Examples 6 to 10: Preparation of resin substrates B2 to B6 Resin substrates B2 to B6 were prepared in the same manner as in Production Example 5, except that laser weldable materials 2 to 6 were used instead of laser weldable material 1.

[0178] (4-7) Production Example 11: Preparation of resin substrate B7 Resin substrate B7 was prepared in the same manner as in Production Example 5, except that the acrylic plate used in Production Example 2 was used instead of the PMMA plate and laser welding material 5 was used instead of laser welding material 1.

[0179] (4-8) Production Examples 12 to 13: Preparation of Resin Substrates B8 to B9 Resin substrates B8 to B9 were prepared in the same manner as in Production Example 11, except that laser welding materials 6 and 7 were used instead of laser welding material 5 in Production Example 11.

[0180] (4-9) Production Example 14: Preparation of resin substrate B10 A resin substrate B10 was prepared in the same manner as in Production Example 5, except that the COP plate used in Production Example 3 was used instead of the PMMA plate and the laser welding material 8 was used instead of the laser welding material 1.

[0181] (4-10) Production Example 15: Preparation of resin substrate B11 In Production Example 5, the PC plate used in Production Example 4 was used instead of the PMMA plate, and the laser welding material 9 was used instead of the laser welding material 1. A resin substrate B11 was prepared in the same manner as in Production Example 5.

[0182] (4-11) Production Examples 16 to 17: Preparation of resin substrates B12 to B13 Resin substrates B12 to B13 were prepared in the same manner as in Production Example 5, except that laser weldable materials 10 to 11 were used instead of the laser weldable material 1 in Production Example 5. Resin substrates B12 to B13 were prepared in the same manner as in Production Example 5.

[0183] (4-12) Production Example 18: Preparation of Resin Substrate C1 After drying the PMMA pellets at 80 ° C for 5 hours, a 100 μm thick PMMA sheet was produced by pressing for 2 minutes at a temperature of 230 ° C and a pressure of 20 MPa using a heating press manufactured by Imoto Machinery Co., Ltd. This was cut into a size of 15 mm × 17 mm to obtain a resin substrate C1. The thickness of the sheet was calculated by measuring at any five points with a micrometer and calculating the average value.

[0184] (4-13) Production Example 19: Preparation of resin substrate C2 The pellets of acrylic resin A obtained in Synthesis Example 9 were dried at 80°C for 5 hours, and then pressed for 2 minutes using a heating press manufactured by Imoto Machinery Works, Ltd. at a temperature of 230°C and a pressure of 20 MPa to produce a 300 μm thick acrylic resin A sheet. This was cut into a size of 37.5 mm × 17 mm to obtain resin substrate C2.

[0185] (4-14) Production Example 20: Preparation of Resin Substrate C3 After drying the acrylic resin A pellets obtained in Synthesis Example 9 at 80 ° C. for 5 hours, a heated press manufactured by Imoto Seisakusho was used to press the acrylic resin A sheet having a thickness of 80 μm for 2 minutes at a temperature of 250 ° C. and a pressure of 20 MPa. The resulting unstretched sheet was cut into a size of 96 mm x 96 mm and sequentially biaxially stretched in the machine direction (MD direction) and the transverse direction (TD direction) at a stretching rate of 240 mm / min at a temperature of 140 ° C. using a Toyo Seiki Seisakusho X-6S. The stretched sheet was heat-treated for 1 minute and cooled to obtain a sheet having a thickness of 20 μm. This was then cut into a size of 15 mm x 17 mm to obtain a resin substrate C3.

[0186] (4-15) Production Example 21: Preparation of resin substrate C4 A PC sheet was prepared in the same manner as in Production Example 18, except that the PMMA pellets in Production Example 18 were changed to PC pellets. The resin substrate C4 was obtained by cutting the sheet to a size of 15 mm × 17 mm.

[0187] (4-16) Production Example 22: Preparation of resin substrate C5 A PSt sheet was prepared in the same manner as in Production Example 18, except that the PMMA pellets in Production Example 18 were changed to PSt pellets, and cut into a size of 15 mm × 17 mm, thereby obtaining a resin substrate C5.

[0188] (4-17) Production Example 23: Preparation of resin substrate C6 An AS sheet was prepared in the same manner as in Production Example 18, except that the PMMA pellets in Production Example 18 were changed to AS pellets, and cut into a size of 15 mm × 17 mm, thereby obtaining a resin substrate C6.

[0189] (4-18) Production Example 24: Preparation of resin substrate D1 The pellet-shaped laser welding material 12 was dried at 80°C for 5 hours, and then pressed for 2 minutes at a temperature of 230°C and a pressure of 20 MPa using a heating press manufactured by Imoto Machinery Co., Ltd. to prepare an absorbent sheet having a thickness of 100 μm. This was cut into a size of 15 mm x 17 mm to obtain a resin substrate D1.

[0190] (4-19) Production Example 25: Preparation of resin substrate D2 Pellet-shaped laser welding material 13 was dried at 80°C for 5 hours, and then pressed for 2 minutes at a temperature of 230°C and a pressure of 20 MPa using a heating press manufactured by Imoto Machinery Co., Ltd. to prepare an absorbent sheet having a thickness of 300 μm. This was cut into a size of 15 mm x 17 mm to obtain resin substrate D2.

[0191] (4-20) Production Example 26: Preparation of Resin Substrate D3 After drying the pellet-shaped laser welding material 14 at 80 ° C. for 5 hours, a sheet having a thickness of 80 μm was produced by pressing for 2 minutes at a temperature of 250 ° C. and a pressure of 20 MPa using a heating press manufactured by Imoto Seisakusho. The obtained unstretched sheet was cut into a size of 96 mm x 96 mm and sequentially biaxially stretched in the machine direction (MD direction) and the transverse direction (TD direction) at a stretching rate of 240 mm / min at a temperature of 140 ° C. using a Toyo Seiki Seisakusho X-6S. The stretched sheet was heat-treated for 1 minute and cooled to produce a 20 μm thick absorbent sheet. This was cut into a size of 15 mm x 17 mm to obtain a resin substrate D3.

[0192] (4-21) Production Example 27: Preparation of resin substrate D4 A resin substrate D4 was prepared in the same manner as in Production Example 24, except that the laser weldable material 15 was used instead of the laser weldable material 12. The thickness of the resin substrate D4 was 100 μm.

[0193] (4-22) Production Example 28: Preparation of resin substrate D5 Resin substrate D5 was prepared in the same manner as in Production Example 24, except that laser weldable material 16 was used instead of laser weldable material 12. The thickness of resin substrate D5 was 80 μm.

[0194] (4-23) Production Example 29: Preparation of resin substrate D6 A resin substrate D6 was prepared in the same manner as in Production Example 24, except that the laser weldable material 17 was used instead of the laser weldable material 12. The thickness of the resin substrate D6 was 120 μm.

[0195] (5) Evaluation of Resin Substrate (5-1) Spectroscopic Measurement of Resin Substrate Using a spectrophotometer (Shimadzu Corporation, UV-3600), the transmission spectra of resin substrates A1 to A4, resin substrates B1 to B13, resin substrates C1 to C6, and resin substrates D1 to D6 prepared in Production Examples 1 to 29 were measured at wavelengths of 300 nm to 1300 nm. The light transmittance was measured at a measurement interval of 1.0 nm, and the transmittance at a wavelength of 1070 nm and the average visible light transmittance in the wavelength range of 380 nm to 780 nm were determined, respectively. The results are shown in Tables 4 and 5.

[0196]

[0197]

[0198] (5-2) Transmission Spectra of Light-Absorbing Layers of Resin Substrates B1 to B6 The transmission spectra of the light-absorbing layers of resin substrates B1 to B6 were determined by taking the difference spectrum between the transmission spectrum of resin substrates B1 to B6 and the transmission spectrum of resin substrate A1. Similarly, the transmission spectra of the light-absorbing layers of resin substrates B7 to B9 were determined by taking the difference spectrum between the transmission spectrum of resin substrates B7 to B9 and the transmission spectrum of resin substrate A2. The transmission spectrum of the light-absorbing layer of resin substrate B10 was determined by taking the difference spectrum between the transmission spectrum of resin substrate B10 and the transmission spectrum of resin substrate A3. The transmission spectrum of the light-absorbing layer of resin substrate B11 was determined by taking the difference spectrum between the transmission spectrum of resin substrate B11 and the transmission spectrum of resin substrate A4. The difference spectrum was calculated by taking the logarithm (log １０ ) and then the difference was subjected to exponential transformation to determine the transmittance (difference spectrum) of the light-absorbing layer. Specifically, the transmittance (difference spectrum) of the light-absorbing layer was determined based on the following formula: Transmittance of the light-absorbing layer (%) = 10^[log １０ (Transmittance of resin substrates B1 to B11) -log １０ (Transmittance of resin substrates A1 to A4)] × 100. The results are shown in Figures 1 to 5.

[0199] (5-3) Transmission Spectra of Resin Substrates D1 to D6 The transmission spectra of resin substrates D1 to D6 were determined, and the results are shown in FIGS. 6 to 10. In addition, the transmission spectra of the dye components of resin substrates D1 to D6 were determined, and the results are shown in FIGS. 11 to 15. The transmission spectra of the dye components of resin substrates D1 to D6 were obtained by plotting the logarithm (log １０ Specifically, the transmittance (difference spectrum) of the dye component of resin substrates D1 to D6 was calculated based on the following formula: Transmittance (%) of dye component of resin substrates D1 to D6 = 10^[log １０ (Transmittance of resin substrates D1 to D6) -log １０ (Transmittance of resin base materials C1 to C6)]×100.

[0200] (6) Laser Welding Test Method (6-1) Example 1 Resin substrate A1 was placed on the side of resin substrate B1 on which the light absorbing layer was formed, and laser light was irradiated from the resin substrate A1 side to obtain test specimen 1. The laser light was irradiated using a laser device (VL-W1, manufactured by Panasonic Corporation), and the laser wavelength was adjusted to 1070 nm, the laser output to 20 to 70 W, and the laser scanning speed to 25 to 1050 mm / sec.

[0201] (6-2) Example 2 Specimen 2 was prepared in the same manner as in Example 1, except that resin base material B2 was used instead of resin base material B1.

[0202] (6-3) Example 3 Specimen 3 was prepared in the same manner as in Example 1, except that resin base material B3 was used instead of resin base material B1.

[0203] (6-4) Example 4 Specimen 4 was prepared in the same manner as in Example 1, except that resin base material B4 was used instead of resin base material B1.

[0204] (6-5) Example 5 Specimen 5 was prepared in the same manner as in Example 1, except that resin base material B5 was used instead of resin base material B1.

[0205] (6-6) Example 6 Specimen 6 was prepared in the same manner as in Example 1, except that resin base material B6 was used instead of resin base material B1.

[0206] (6-7) Example 7 Test piece 7 was prepared in the same manner as in Example 1, except that resin substrate A2 was used instead of resin substrate A1 and resin substrate B7 was used instead of resin substrate B1.

[0207] (6-8) Example 8 Specimen 8 was prepared in the same manner as in Example 1, except that Resin substrate B8 was used instead of Resin substrate B7 in Example 7.

[0208] (6-9) Example 9 Specimen 9 was prepared in the same manner as in Example 1, except that Resin substrate B9 was used instead of Resin substrate B7 in Example 7.

[0209] (6-10) Example 10 A test piece 10 was prepared in the same manner as in Example 1, except that resin substrate A3 was used instead of resin substrate A1 and resin substrate B10 was used instead of resin substrate B1.

[0210] (6-11) Example 11 Test specimen 11 was prepared in the same manner as in Example 1, except that resin substrate A4 was used instead of resin substrate A1 and resin substrate B11 was used instead of resin substrate B1.

[0211] (6-12) Comparative Example 1 Resin substrates A1 were stacked on each other and irradiated with laser light to obtain specimen 12.

[0212] (6-13) Comparative Example 2 Resin substrates A2 were stacked on each other and irradiated with laser light to obtain specimen 13.

[0213] (6-14) Comparative Example 3 Resin substrates A3 were stacked on each other and irradiated with laser light to obtain specimen 14.

[0214] (6-15) Comparative Example 4 Resin substrates A4 were stacked on each other and irradiated with laser light to obtain specimen 15.

[0215] (6-16) Comparative Example 5 Specimen 16 was prepared in the same manner as in Example 1, except that resin base material B12 was used instead of resin base material B1.

[0216] (6-17) Comparative Example 6 Specimen 17 was prepared in the same manner as in Example 1, except that resin base material B13 was used instead of resin base material B1.

[0217] (6-18) Example 12 Resin substrate D1 was sandwiched between two resin substrates A1 and stacked together, and then irradiated with laser light to obtain specimen 18.

[0218] (6-19) Example 13 Resin substrate A2 was superimposed on resin substrate D2, and laser light was irradiated from the resin substrate A2 side to obtain specimen 19.

[0219] (6-20) Example 14 Resin substrate D3 was sandwiched between two resin substrates A2 and stacked together, and then irradiated with laser light to obtain specimen 20.

[0220] (6-21) Example 15 Resin substrate D4 was sandwiched between two sheets of resin substrate A4 and stacked together, and then irradiated with laser light to obtain specimen 21.

[0221] (6-22) Example 16 Resin substrate D5 was sandwiched between two PSt plates, which were then stacked together and irradiated with laser light to obtain specimen 22. The PSt plate was prepared by cutting a polystyrene plate (size 50 mm × 100 mm × 2 mm) to a size of 25 mm × 17 mm using an ultrasonic cutter (manufactured by Suzuki Corporation, SUW-30CT).

[0222] (6-23) Example 17 Resin substrate D6 was sandwiched between two AS plates, which were then stacked together and irradiated with laser light to obtain specimen 23. The AS plate was prepared by cutting an acrylonitrile-styrene copolymer plate (size 50 mm × 100 mm × 2 mmt) to a size of 25 mm × 17 mm using an ultrasonic cutter (manufactured by Suzuki Corporation, SUW-30CT).

[0223] (6-24) Comparative Example 7 Resin substrate C1 was sandwiched between two resin substrates A1 and stacked together, and then irradiated with laser light to obtain specimen 24.

[0224] (6-25) Comparative Example 8 Resin substrate A2 was superimposed on resin substrate C2, and laser light was irradiated from the resin substrate A2 side to obtain specimen 25.

[0225] (6-26) Comparative Example 9 Resin substrate C3 was sandwiched between two resin substrates A2 and stacked together, and then irradiated with laser light to obtain specimen 26.

[0226] (6-27) Comparative Example 10 Resin substrate C4 was sandwiched between two sheets of resin substrate A4, and the two sheets were stacked together, and irradiated with laser light to obtain specimen 27.

[0227] (6-28) Comparative Example 11 Resin substrate C5 was sandwiched between the two PSt plates used in Example 16 and stacked together, and then irradiated with laser light to obtain specimen 28.

[0228] (6-29) Comparative Example 12 Resin substrate C6 was sandwiched between the two AS plates used in Example 17 and stacked together, and then irradiated with laser light to obtain specimen 29.

[0229] (7) Measurement of Welding Strength of Test Specimens For each of the test specimens 1 to 29 (size 37.5 mm x 17 mm) prepared in Examples 1 to 17 and Comparative Examples 1 to 12, the welding strength was measured using a digital force gauge (Imada Co., Ltd., ZTS-1000N). In Examples 1 to 11 and Comparative Examples 5 to 6, the tips of the resin substrate A and the resin substrate B were fixed to a jig, respectively, and a tensile load test (test speed 10 mm / min) was performed to measure the welding strength. In Examples 12, 14 to 17 and Comparative Examples 1 to 4, 7, 9 to 12, the tips of one resin substrate A (or resin plate) and the other resin substrate A (or resin plate) were fixed to a jig, respectively, and a tensile load test (test speed 10 mm / min) was performed to measure the welding strength. In Example 13 and Comparative Example 8, the tips of resin substrate A and resin substrate C or D were fixed to a jig, and a tensile load test (test speed 10 mm / min) was performed to measure the welding strength. A welding strength of 10 MPa or more was evaluated as "○", and a welding strength of less than 10 MPa or no welding was performed was evaluated as "×". The results are shown in Tables 6 and 7. Tables 6 and 7 also show the average visible light transmittance in the wavelength range of 380 nm to 780 nm of the dye component of the light-absorbing layer of resin substrate B and resin substrate D (absorbent sheet) in each Example and Comparative Example. The average visible light transmittance of the light-absorbing layer of resin substrate B was determined from the transmission spectrum of the light-absorbing layer of resin substrate B determined in Section (5-2), and the average visible light transmittance of the dye component of resin substrate D was determined from the transmission spectrum of the dye component of resin substrate D determined in Section (5-3).

[0230]

[0231]

[0232] The laser weldable material of the present invention can be used for laser welding applications.

Claims

1. A laser welding material containing a resin and a cyanine compound represented by the following formula (1): [In formula (1), L represents a methine chain having 3 to 9 carbon atoms, each methine group contained in the methine chain may independently have a substituent, and the substituents may be bonded to each other; A ＋ and A represents a group bonded to the methine chain L; X － represents a monovalent anion having a pKa of -8.0 or less of the conjugate acid.] The cyanine compound is a laser welding material having an average transmittance of 81% or more in a wavelength range of 380 nm to 780 nm when the transmittance at the absorption maximum wavelength is 10% in a wavelength range of 300 nm to 1,300 nm.

2. The laser welding material according to claim 1, wherein the cyanine compound has a maximum absorption wavelength in the range of 750 nm to 1,300 nm.

3. The laser welding material according to claim 1, further comprising a solvent.

4. The laser welding material according to claim 1, wherein the resin is a thermoplastic resin.

5. The laser welding material according to claim 1, wherein the resin is a (meth)acrylic resin containing a structural unit having a ring structure in the main chain, and the ring structure contains at least one selected from the group consisting of a lactone ring structure, a glutarimide structure, and a maleimide structure.

6. In the formula (1), A ＋ and A represents any one of groups represented by the following formulas (2) to (7): [In formula (2), R １１ represents an organic group; R １２ ~R １７ each independently represents a hydrogen atom, a halogen atom or an organic group, and * represents a bonding site with the methine chain L in formula (1). [In formula (3), R ２１ represents an organic group, ring S represents a hydrocarbon ring having a fused ring structure which may have a substituent, or a heterocycle having a fused ring structure which may have a substituent, and is spiro-bonded to the adjacent pyrrole ring, ring T represents an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, or a fused ring containing these ring structures which may have a substituent, and * represents a bonding site with the methine chain L in formula (1). [In formula (4), R ３１ represents an organic group; R ３２ ~R ３５ each independently represents a hydrogen atom, a halogen atom, or an organic group; ３２ and R ３３ , R ３３ and R ３４ , R ３４ and R ３５ may be linked together to form a ring, １ is an oxygen atom, a sulfur atom, CH=CH or CR ３６ R ３７ represents R ３６ and R ３７ each represents an organic group, and * represents a bonding site with the methine chain L in formula (1). [In formula (5), R ４１ ~R ４４ each independently represents a hydrogen atom, a halogen atom, or an organic group; ４１ and R ４２ , R ４３ and R ４４ may be linked together to form a ring, ２ is an oxygen atom, a sulfur atom or NR ４５ represents R ４５ represents an organic group, and * represents a bonding site with the methine chain L in formula (1). [In formula (6), R ５１ ~R ５４ each independently represents a hydrogen atom, a halogen atom or an organic group; ３ is an oxygen atom, a sulfur atom or NR ５５ represents R ５５ represents an organic group, and * represents a bonding site with the methine chain L in formula (1). [In formula (7), R ６１ ~R ６３ , R ６５ ~R ６７ each independently represents a hydrogen atom, a halogen atom or an organic group; R ６４ represents an organic group, and * represents a bonding site with the methine chain L in formula (1).

7. A laminate comprising: a substrate; and a light absorbing layer provided on the substrate and formed from the laser weldable material according to any one of claims 1 to 6.

8. The laminate according to claim 7, wherein the light absorbing layer has an average transmittance of 80% or more in the wavelength range of 380 nm to 780 nm.

9. An absorber formed from the laser weldable material according to any one of claims 1 to 6.

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