JP2008222903A - Light-absorbing resin composition for laser welding, light-absorbing resin molded article, and method for producing light-absorbing resin molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-absorbing resin composition for laser welding which has thermal stability which conventional organic light-absorbing agents do not have and gives transparency and translucency after laser welding which is not obtained by conventional carbon light-absorbing agents to plastic members, and to provide a light-absorbing resin molded item. <P>SOLUTION: The light-absorbing resin composition for laser welding comprises a polymer dispersing agent having a glass transition temperature of 30°C or higher and laser beam-absorbing particulates, wherein the laser beam-absorbing particulates are nitride particulates selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride and tantalum nitride. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser-welding light-absorbing resin composition and a light-absorbing resin molding used when plastic members are joined by a laser welding method, and a method for producing a light-absorbing resin molding. More specifically, the laser welding light has the thermal stability not found in conventional organic light absorbers, and gives the plastic member transparency and translucency after laser welding that cannot be obtained with conventional carbon light absorbers. The present invention relates to an absorbent resin composition, a light-absorbing resin molded body, and a method for producing a light-absorbing resin molded body.

  In recent years, an opportunity to apply a laser welding method as a joining method of a thermoplastic resin is increasing. This is because when the laser welding method is used, even a member having a fine and complicated joining interface can be easily and stably joined without vibration, the generation of burrs and smoke can be improved, and the appearance of the joined product can be improved. This is considered to be due to the advantage that the degree of freedom of design increases.

  In the laser welding method, usually, one of the plastic members to be joined is composed of a light-transmitting resin molded body, and the other is composed of a light-absorbing resin molded body that absorbs laser light and generates heat.

  When laser irradiation is performed on the plastic member from the side of the light-transmitting resin molded body, the light-absorbing resin molded body is first dissolved, and then the periphery of the dissolved light-absorbing resin molded body is Heat is transferred to the side, melting occurs and bonding is performed.

  As a laser light source, an Nd: YAG laser with a wavelength of 1064 nm and a semiconductor laser with a wavelength of 800 to 1000 nm are mainly used. Therefore, a material that efficiently absorbs a near infrared wavelength of 800 to 1200 nm is a light absorbing resin composition. Used as a thing.

  The light absorbing resin composition includes an organic phthalocyanine compound, a cyanine compound, an aminium compound, an imonium compound, a squalium compound, a polymethine compound, an anthraquinone compound, an azo compound, or carbon in the inorganic system. A resin composition containing black is known (see Patent Document 1).

  Patent Document 2 proposes a light-absorbing resin composition in which a metal simple substance, salt, oxide, hydroxide or the like is added together with copper phosphonate having an aromatic ring in order to improve sensitivity to laser. Has been. Specific examples of the metal oxide include silicon oxide, titanium oxide, aluminum oxide, iron oxide, magnesium oxide, zinc oxide, cobalt oxide, lead oxide, tin oxide, antimony oxide, indium oxide, manganese oxide, molybdenum oxide, Resin compositions containing nickel oxide, copper oxide, palladium oxide, lanthanum oxide, antimony-doped tin oxide (ATO), indium-doped tin oxide (ITO) and the like are presented.

Patent Document 3 proposes a light-absorbing resin composition in which tin-added indium oxide (ITO) or antimony-added tin oxide (ATO) is added as an inorganic material having a light absorption capability in the laser wavelength range. .
JP 2004-148800 A JP 2005-290087 A International Publication WO2005 / 084955 A1 Pamphlet

  However, according to the study by the present inventors, the organic light-absorbing resin composition (laser light-absorbing material) described in Patent Document 1 generally has a narrow absorption wavelength width, and is compared for obtaining sufficient heat generation. Requires a large amount of addition. Moreover, since it is inferior in heat stability, decomposition | disassembly occurs in parallel with heat_generation | fever and depending on laser irradiation conditions, a uniform stable joined body may not necessarily be obtained.

  On the other hand, the inorganic carbon material described in Patent Document 1 has high thermal stability. However, the plastic member is colored black due to absorption itself in the visible light wavelength region, which is inconvenient for obtaining a transparent plastic joint member or a member that dislikes blackening of the joint portion. However, in the medical field and the like, there is an increasing demand for bonding that is transparent and colorless. Also, carbon black is easy to agglomerate, and if the dispersion state in the host resin is uneven or agglomerated, heat generation due to laser light absorption will be uneven and partial unevenness will occur in the weld. There are problems such as the occurrence of general foaming and the long welding time.

  The light-absorbing resin composition added with a simple substance of metal, salt, oxide, hydroxide, etc. together with copper phosphonate having an aromatic ring described in Patent Document 2 has insufficient sensitivity to laser light, which is a problem. It is necessary to add a large amount of the composition in order to join without any problems. However, the addition of a large amount of the composition may change the basic physical properties of the resin molded body itself, which causes problems such as a decrease in mechanical strength.

  The light-absorbing resin composition added with tin-doped indium oxide (ITO) and antimony-doped tin oxide (ATO) described in Patent Document 3 is excellent in transparency, but the infrared absorption rate per unit weight is higher than that of carbon or the like. Is much lower. In addition, since absorption starts from near infrared rays having a relatively long wavelength of 1000 nm or more, there is a problem that absorption at a wavelength of 800 to 1000 nm of a semiconductor laser or a wavelength of 1064 nm of an Nd: YAG laser is substantially very weak. For this reason, in order to perform appropriate laser welding, it is necessary to add a large amount of the composition to a plastic member. However, addition of a large amount of the composition not only changes the basic physical properties of the member itself, but also increases cost constraints. In particular, ITO has a large resource and price problem.

  The present invention has been made in consideration of the above-mentioned circumstances, and the problem to be solved is that uniform heat generation is generated by laser light and stable laser welding is possible, and the welded portion maintains transparency. An object of the present invention is to provide a laser-absorbing light-absorbing resin composition, a light-absorbing resin molded body, and a method for producing the light-absorbing resin molded body.

As a result of repeated researches by the present inventors to solve the above-mentioned problems, the characteristics required as a light-absorbing resin for laser welding are:
1. Having a strong absorption over a near infrared wavelength of 800 to 1200 nm, which is near the wavelength region of the laser, and having a high absorption coefficient,
2. Less absorption at 380 to 780 nm which is a visible light wavelength,
3. The solubility or dispersibility of the light-absorbing material in the host resin is high,
I came up with that.

  Therefore, the present inventors have strong absorption over the near-infrared wavelength range of 800 to 1200 nm, which is the wavelength range of the laser beam used for laser welding, and can maintain transparency because the absorption is sufficiently small in visible light, Laser-absorbing light-absorbing resin composition and light-absorbing resin molded body capable of stable laser welding by generating uniform heat generation by laser light without impairing the transparent appearance of the joint-welded portion, and light-absorbing resin-molded body The manufacturing method was studied.

  As a result of the research, the present inventors, in a laser-welding light-absorbing resin composition containing a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser-light-absorbing fine particles, nitrided as laser-light-absorbing fine particles. By using at least one kind of nitride fine particles selected from titanium, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride, the laser strongly absorbs light in the wavelength range of Nd: YAG laser and semiconductor laser. The inventors have found that a light-absorbing resin composition for laser welding capable of transmitting light having a wavelength in the visible light range and maintaining the transparency of an object can be obtained while facilitating welding, and has led to the present invention.

    At least one nitride fine particle selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride has a large amount of free electrons and the wavelength of plasmon excitation is in the near infrared region. Therefore, it is considered that the above characteristics are exhibited.

That is,
The first configuration is
A laser-absorbing light-absorbing resin composition comprising a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser-absorbing fine particles,
The laser-welding light-absorbing resin composition, wherein the laser-light-absorbing fine particles are at least one kind of nitride fine particles selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride It is.

The second configuration is
The average particle size of the nitride fine particles is 1000 nm or less. The light-absorbing resin composition for laser welding according to the first configuration.

The third configuration is
The laser-welding light-absorbing resin composition according to either the first or second configuration is diluted and kneaded with a polymer dispersant and a thermoplastic resin contained in the laser-welding light-absorbing resin composition. A light-absorbing resin molded article molded by
The light characterized in that the content of nitride fine particles in the surface layer of the light-absorbing resin molding is 3 mm or less from the surface is 0.001 g / m ² or more and 0.4 g / m ² or less. This is an absorbent resin molding.

The fourth configuration is
The laser-welding light-absorbing resin composition according to either the first or second configuration is diluted and kneaded with the polymer dispersant and the thermoplastic resin contained in the laser-welding light-absorbing resin composition. A light-absorbing resin molded article,
The light-absorbing resin molded body is characterized in that the shape of the molded light-absorbing resin molded body is a plate shape or a film shape.

The fifth configuration is
The thermoplastic resin is at least one selected from the group consisting of acrylic resin, polycarbonate resin, styrene resin, low density polyethylene resin, polypropylene resin, polyurethane resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and fluororesin. The light-absorbing resin molded body according to any one of the third and fourth configurations, which is a resin.

The sixth configuration is
A light-absorbing resin molded article, wherein the light-absorbing resin composition according to any one of the first and second configurations is diluted with a binder and coated on the surface of a substrate.

The seventh configuration is
The light-absorbing resin molded body according to any one of the third to sixth configurations is a light-absorbing resin molded body having an absorption maximum at a wavelength of 500 to 1000 nm.

The eighth configuration is
Polymer dispersion in which a laser welding light absorbing resin composition containing a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser light absorbing fine particles is contained in the laser welding light absorbing resin composition A method for producing a light-absorbing resin molded article that is diluted and kneaded with an agent and a thermoplastic resin,
A light-absorbing resin composition in which the laser light-absorbing fine particles are at least one kind of nitride fine particles selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride; Using a thermoplastic resin, the content of nitride fine particles in the surface layer of the light-absorbing resin molded body and in a region of 3 mm or less from the surface is 0.001 g / m ² or more and 0.4 g / m ² or less. The method for producing a light-absorbing resin molded body is characterized in that the light-absorbing resin molded body is manufactured by diluting as described above, kneading and molding.

According to the present invention, a laser-welding light-absorbing resin composition containing a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser-light-absorbing fine particles includes titanium nitride, zirconium nitride, At least one kind of nitride fine particles selected from hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride are used, and these fine particles have a solid powder shape in which they are highly dispersed in a polymer dispersant. ing.

  As a result of having the above configuration, the laser-absorbing light-absorbing resin composition can be easily molded into a laser-light-absorbing resin molding, and strongly absorbs light in the wavelength range of Nd: YAG lasers and semiconductor lasers to facilitate laser welding. On the other hand, since the transparency of the object can be maintained almost through the light having a wavelength in the visible light range and a transparent welding interface with less coloring can be obtained, the application range of laser welding is increased, and the heat Since it is excellent in stability, it can provide a stable joint between plastics, which is extremely useful industrially.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The laser-welding light-absorbing resin composition containing a polymer dispersant having a glass transition temperature of 30 ° C. or higher and a laser-light-absorbing fine particle according to the present embodiment is composed of titanium nitride, zirconium nitride, and nitride. It is characterized by being at least one kind of nitride fine particles selected from hafnium, vanadium nitride, niobium nitride, and tantalum nitride.

  The laser light-absorbing fine particles of the present embodiment are inorganic fine particles having a function of absorbing light in the laser light wavelength region, and are fine particles that retain a large amount of free electrons and cause plasma resonance vibration. When laser light is incident on the fine particles, free electrons are excited in accordance with the frequency of the light to cause collective vibration of electrons, and energy is absorbed and radiated. The absorption wavelength at this time depends on the free electron density and the effective mass of electrons, and depending on the type of fine particles, those having a plasma absorption wavelength in the vicinity of the wavelength range of 800 to 1200 nm of Nd: YAG laser or semiconductor laser light. is there. When electron energy loss spectroscopy (EELS) with high energy resolution is used, an energy loss peak due to plasmon excitation can be directly observed.

Specific examples of the laser light absorbing fine particles of the present embodiment include nitride fine particles such as titanium nitride TiN, zirconium nitride ZrN, hafnium nitride HfN, vanadium nitride VN, niobium nitride NbN, and tantalum nitride TaN. These nitrides are intermetallic compounds having a NaCl type (B1 type) crystal structure, but have characteristics as non-stoichiometric compounds (beltride compounds). For example, titanium nitride is represented by TiN _x. , X is known to have a wide range of 0.8 <X <1.16. Since the absorption characteristics of near-infrared when nano-particles are formed can be seen in a wide range of non-stoichiometry of such a composition, in the present invention, it means a nitride having a NaCl-type crystal structure including non-stoichiometry. It shall be.

The nitride fine particles used in the present invention may be partially or wholly replaced with oxynitride. These nitride fine particles are preferably not oxidized on the surface, but are usually slightly oxidized, and it is inevitable that oxidation of the surface occurs in the fine particle dispersion process to some extent. However, even in that case, there is no change in the effectiveness of developing the near infrared absorption effect. Further, these nitride fine particles have a greater near-infrared absorption effect as the crystal completeness is higher, but even if the crystallinity is low and X-ray diffraction produces a very broad diffraction peak, If the basic atomic bond is composed of a bond between each metal element and nitrogen, a near-infrared absorbing effect is exhibited.
The laser light-absorbing fine particles have a maximum value of absorption at a wavelength of 500 to 1000 nm when dispersed in a sufficiently small size. Since the wavelength near the maximum value has a sufficiently large absorption coefficient, the laser beam in the wavelength range of 800 to 1200 nm is sufficiently absorbed to generate heat.

  The nitride fine particles described above may be used alone, but it is also preferable to use a mixture of two or more kinds. According to the experiments of the present inventors, in the composition in which these fine particles are sufficiently finely and uniformly dispersed, the laser light-absorbing fine particles have a maximum value of absorption at a wavelength of 500 to 1000 nm. Since the wavelength near the maximum value has a sufficiently large absorption coefficient, the laser beam in the wavelength range of 800 to 1200 nm is sufficiently absorbed to generate heat.

  Considering that the visible light wavelength is 380 to 780 nm and the visibility is a bell-shaped peak with a peak at around 550 nm, such a film effectively transmits visible light and effectively uses light of other wavelengths. Can be absorbed.

  The particle diameter of the laser light absorbing fine particles used in the present embodiment is arbitrary as long as it functions as a laser light absorbing component, but is preferably 1000 nm or less, more preferably 200 nm or less. If the particle diameter is 1000 nm or less, fine particles or coarse aggregate particles formed by agglomeration of fine particles do not serve as a light scattering source for the molded light-absorbing resin molded product, and the transparent molded product after laser welding looks transparent without being clouded. is there. Further, if the particle diameter is 1000 nm or less, the attenuation of the laser light absorption itself is small, and therefore the particle diameter is preferably 1000 nm or less.

  The laser light-absorbing fine particles used in the present embodiment are not completely transparent in the visible light region, and have some color depending on the kind of fine particles, the particle diameter, the state of dispersion aggregation, and the like. By making the fine particle size smaller and more uniformly dispersed, the scattered light by the fine particles is reduced. For example, when the fine particles are uniformly dispersed to an average fine particle size of 200 nm or less, the Rayleigh scattering mode is set, and the light is emitted with visible light. Even if it is a black material that does not pass through, the aggregate of the fine particles produces transparency under visible light.

The dispersion state of the laser-absorbing fine particles in the host thermoplastic resin is extremely important for the characteristics of the laser-welding light-absorbing resin composition. When the fine particles are sufficiently dispersed without agglomeration, the final colored state of the composition becomes uniform, and the heat generation site by laser irradiation becomes uniform, so that the appearance after welding is good. Become. On the other hand, when the fine particles are not sufficiently dispersed and aggregated in the host thermoplastic resin, not only the final colored state becomes non-uniform, but also the heat generation site due to laser irradiation becomes non-uniform. Become. And the local site | part of the light-absorbing resin composition for laser welding foams due to the nonuniformity of the heat generating site, or the appearance is poor.
In order to avoid foaming at the local site and poor appearance in the laser-absorbing light-absorbing resin composition, it is preferable to take the following steps.
(1) A dispersion in which laser light absorbing fine particles are uniformly dispersed in a solvent together with a dispersant is produced.
(2) Using a heating mixer such as a vacuum dryer, hot air dryer, Henschel mixer or the like, the solvent is removed from the dispersion by heating to produce the laser-welded light absorbing composition.
(3) The produced laser-absorbing light-absorbing composition is diluted, kneaded, and molded with the dispersant and the thermoplastic resin to produce a desired light-absorbing resin molded body.

  Here, the present inventors finally found that the dispersion state of the laser-light-absorbing fine particles in the light-absorbing resin molding obtained in the step (3) is the dispersion obtained in the production of the fine particle dispersion in the step (1). The laser-welding light absorbing composition obtained in the step (2), which is a solid powder that is easy to handle, and that is highly dependent on the state and the advanced dispersion state realized in the fine particle dispersion in the step (1) I came to realize that it is important to hold the object.

  Therefore, the present inventors examined a dispersant suitable for the laser light-absorbing fine particles in the preparation of the fine particle dispersion in the step (1). Based on the results of many studies, the present inventors have found that the dispersant is not a dispersant having a short molecule and having a low steric hindrance effect even if it adheres to the surface of the fine particle, but has a long molecule and adheres to the fine particle surface. Then, it has been found that a polymer dispersant that prevents aggregation of the fine particles is suitable due to its steric hindrance.

  Furthermore, the glass transition temperature of the polymer dispersant needs to be 30 ° C. or higher. If the glass transition temperature of the polymer dispersant is 30 ° C. or higher, after removing the solvent in the step (2), the polymer dispersant will solidify in a jelly shape and become inconvenient to handle such as stickiness. This is because it can be avoided.

  The polymer dispersant is preferably a polymer in which various lipophilic functional groups and hydrophilic functional groups are attached to the terminal of the main polymer skeleton including polyester, acrylic, and urethane. . The type and blending amount of the polymer dispersant are appropriately determined according to the type of laser light absorbing fine particles to be dispersed and the surface characteristics thereof. Generally, the blending amount of the polymer dispersant is preferably about 2 to 10 times the weight of the laser light absorbing fine particles.

  By blending an appropriate amount of the polymer dispersant, the dispersion uniformity of the fine particles in the finally obtained light-absorbing resin molding can be maintained. On the other hand, by avoiding excessive addition of the polymer dispersant, molding is performed according to the degree of affinity between the polymer dispersant and the resin that is the main component of the finally obtained light-absorbing resin molding. Inconveniences such as cloudiness on the body can be avoided.

  In order to uniformly disperse the laser light absorbing fine particles, the dispersant and the solvent, any method and apparatus for uniformly dispersing the fine particles in the resin can be selected. As an example, a method and apparatus such as a bead mill, a ball mill, a sand mill, and an ultrasonic dispersion apparatus can be used.

  The laser-absorbing light-absorbing resin composition can be diluted, kneaded and molded with a thermoplastic resin to obtain a light-absorbing resin molding directly. Further, the laser welding light-absorbing resin is diluted and kneaded with a thermoplastic resin to produce a granular, pellet-shaped masterbatch mainly containing the laser-welding light-absorbing resin composition. The final light-absorbing resin molding is further diluted, kneaded and molded with the same thermoplastic resin molding material as the thermoplastic resin or a thermoplastic resin molding material compatible with the thermoplastic resin of the masterbatch. It is also possible to obtain

  For the above dilution and kneading, mixers such as ribbon blender, tumbler, nauter mixer, Henschel mixer, super mixer, planetary mixer, banbury mixer, kneader, roll, kneader ruder, single screw extruder, twin screw extruder, etc. The melt kneader can be used. In this dilution and kneading process, stabilizers, lubricants, fillers, viscosity modifiers, conductivity-imparting agents, antioxidants, release materials, reinforcing agents such as glass fibers and carbon fibers, dyes, pigments, and other materials as necessary It is possible to add additives. However, in any step, it is important that the dispersibility of the laser-absorbing fine particles is kept sufficiently uniform in the laser-absorbing light-absorbing resin composition. This is because if the dispersibility of the laser light-absorbing fine particles is kept sufficiently uniform in the dilution, kneading and molding steps, the initial dispersion uniformity is hardly lost in the subsequent steps.

  As described above, in the present embodiment, the thermoplastic resin for diluting the laser-absorbing light-absorbing resin composition is the same thermoplastic resin as the polymer dispersant, or the compatible polymer dispersant. Different thermoplastic resins can be used.

  As the thermoplastic resin, a thermoplastic resin such as acrylic resin, styrene resin, fluororesin, polycarbonate resin, low density polyethylene resin, polypropylene resin, polyurethane resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, or the like is used. Is preferred.

  For example, as acrylic resins, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate are used as main raw materials, and acrylic acid esters having 1 to 8 carbon atoms, vinyl acetate, styrene, acrylonitrile, methacryloyl as required. Examples thereof include polymers or copolymers using nitrile or the like as a copolymerization component. For example, a copolymer obtained by adding methyl methacrylate to 50 to 99.95 mol% and another copolymerizable monomer such as alkyl acrylate in a proportion of 0.05 to 50 mol% can be mentioned. It is done.

  Examples of the styrene resin include polystyrene, acrylonitrile-styrene copolymer, methyl methacrylate-styrene copolymer, acrylonitrile-methyl methacrylate-styrene copolymer, acrylonitrile-butadiene-styrene resin, acrylonitrile-acrylic rubber- Examples thereof include copolymers obtained by adding 0 to 70 mol% of a copolymerizable monomer to 30 to 100 mol% of styrene, such as styrene resin and acrylonitrile-EPDM-styrene resin.

  Further, for example, as the fluororesin, polyfluorinated ethylene, polydifluorinated ethylene, polytetrafluoroethylene, ethylene-2 fluoroethylene copolymer, ethylene-4 fluoroethylene copolymer, tetrafluoroethylene- Examples include perfluoroalkoxyethylene copolymers.

In the obtained light-absorbing resin molded body, at least one kind selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride in the surface layer and in a region of 3 mm or less from the surface. It is desirable that the content of the nitride fine particles is 0.001 g / m ² or more and 0.4 g / m ² or less.
Here, the region that defines the content of the nitride fine particles is the surface layer of the light-absorbing resin molded body and the region that is 3 mm or less from the surface when the light-absorbing resin molded body is irradiated with laser. This is because the portion that melts and contributes to the bonding is substantially the surface layer of the light-absorbing resin molded body and is an area of 3 mm or less from the surface.

  In the surface layer of the light-absorbing resin molded body, if the content of the nitride fine particles is excessive in a region of 3 mm or less from the surface, a member having excessively deep indigo coloration is obtained. Furthermore, when the laser is irradiated, the amount of heat generated locally increases too much, causing the resin and the dispersant to evaporate, resulting in problems such as the generation of bubbles around the welded part. On the other hand, if the content is too small, the energy of the laser cannot be sufficiently absorbed when the laser is irradiated. As a result, even if the laser power is increased, the laser heat generation amount of the light transmitting resin and the light absorbing resin molded body becomes approximately the same, and both the light transmitting resin and the light absorbing resin molded body are dissolved or deformed. Or problems such as poor bonding.

To avoid these problems, in the region from a to the surface a surface layer less 3mm of the light-absorbent resin molding, the content of the nitride particles are of 0.001g / m ² ~0.4g / m ² It is preferable to be within the range.

  In the region of 3 mm or less from the surface, the measurement of the content of the nitride fine particles is such that when the thickness of the plastic member is 3 mm or less, the ratio of the weight of the nitride fine particles to the weight of the plastic member is the content. When the thickness exceeds 3 mm, a cross-sectional transmission electron micrograph of the molded body is taken, and the area fraction is calculated from the area of the nitride fine particles contained in the region from the surface to the thickness of 3 mm. The volume fraction was calculated as if it was uniformly contained in the molded product, and this was taken as the content.

  If necessary, the light-absorbing resin molded body may be a viscosity modifier, a conductivity-imparting material, an antioxidant, a stabilizer, a lubricant, a filler, a reinforcing material such as glass fiber or carbon fiber, a dye, or a pigment. Or you may contain 2 or more types.

  The shape of the light-absorbing resin molding can be molded into an arbitrary shape as necessary, and can be molded into a flat shape, a curved surface shape, or other complicated shapes. Moreover, the thickness of a planar molded object can be adjusted to arbitrary thickness from plate shape to film shape as needed. Furthermore, the resin sheet formed into a flat shape can be formed into an arbitrary shape such as a spherical shape by post-processing.

  Examples of the method for molding the light-absorbing resin molded body include arbitrary methods such as injection molding, extrusion molding, compression molding, and rotational molding. In particular, a method of obtaining a molded product by injection molding and a method of obtaining a molded product by extrusion molding are preferably employed. As a method for obtaining a plate-like or film-like molded article by extrusion molding, the molded thermoplastic resin is produced by a method in which a molten thermoplastic resin extruded using an extruder such as a T-die is taken out while being cooled by a cooling roll.

  When a resin molding can be produced by casting a monomer solution such as an acrylic resin or a fluororesin, the above laser-absorbing light-absorbing resin composition is mixed and dissolved in the acrylic syrup stock solution, or directly nitride fine particles The dispersion may be mixed and dissolved, cast into a mold for molding, and then formed into a molded body through a polymerizing step. In this case, the solvent and dispersant contained in the fine particle dispersion are selected from those compatible with the monomer liquid, initiator, crosslinking agent, and other additives usually contained in the acrylic syrup stock solution. This is because these solvents and dispersants inhibit the polymerization process of the acrylic polymer and, as a result, avoid the formation of voids in the resin molded body.

  The nitride fine particles, which are laser light absorbing fine particles, may be uniformly dispersed throughout the light absorbing resin molded body, or may be uniformly dispersed in the coating film on the surface of the light absorbing resin molded body. It may be. The coating film includes a case where the laser light absorbing fine particles are uniformly dispersed and contained in the surface layer formed by coextrusion used in the case of extrusion sheet molding.

  Depending on the method of manufacturing the molded body, the distribution state of the dispersed fine particles is largely divided as described above, but when the light-absorbing resin molded body is irradiated with a laser, the part that contributes to the bonding by melting is substantially light. It is a surface layer of the absorbent resin molding, and is an area of 3 mm or less from the surface. Therefore, regardless of the manufacturing method, as described above, the region defining the content of the nitride fine particles is the surface layer of the obtained light-absorbing resin molded body and is a region of 3 mm or less from the surface.

  As a method for uniformly dispersing the laser light absorbing fine particles in the coating film on the surface of the light absorbing resin molded body, first, the laser light absorbing fine particles are made into an arbitrary solvent by using a method such as a bead mill, a ball mill, a sand mill, or an ultrasonic dispersion. And a laser light-absorbing fine particle dispersion dispersed in a dispersing agent, and after adding a binder resin to this, coating the surface of the substrate, evaporating the solvent and curing the binder resin by a predetermined method, A coating thin film in which fine particles are dispersed in a medium can be formed. Although the thickness of a coating film is not specifically limited, The range of about 1 micrometer-100 micrometers is preferable. The coating method is not particularly limited as long as the fine particle-containing resin can be uniformly coated on the surface of the substrate, and examples thereof include a bar coating method, a gravure coating method, a spray coating method, a dip coating method, screen printing, and brush coating. Can be mentioned. In addition, a material in which fine particles are directly dispersed in a binder resin is environmentally and industrially preferable because it is not necessary to evaporate the solvent after coating on the substrate surface.

  As the binder resin, for example, a UV curable resin, a thermosetting resin, an electron beam curable resin, a room temperature curable resin, a thermoplastic resin, or the like can be selected according to the purpose.

  Specifically, polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluorine resin, polycarbonate resin, acrylic resin And polyvinyl butyral resin. Also, a binder using a metal alkoxide can be used. Representative examples of the metal alkoxide include alkoxides such as Si, Ti, Al, and Zr. A binder using these metal alkoxides can be hydrolyzed and heated to form an oxide film.

  The bonding surface between the light-transmitting resin member to be laser-welded and the light-absorbing resin molding may be a flat surface or a concave and convex fitting. It may be coated on one side or both sides of the joint surface.

  Irradiation conditions of the laser beam to be irradiated can be appropriately determined. Usually, the laser output is in the range of 5 to 500 W, the scanning speed is in the range of 2 mm / s to 500 mm / s, and the laser beam irradiation angle is irradiated perpendicularly to the bonding surface. Is preferred.

  Examples of the present invention will be specifically described below together with comparative examples. However, the present invention is not limited to the following examples.

(Example 1)
Fine particles of titanium nitride TiN were prepared by a thermal plasma method. It was confirmed by powder X-ray diffraction that the TiN fine particles were a TiN single phase having a NaCl type crystal structure.

  A toluene solution of 5% by weight of the TiN fine particles and a styrene / acrylic polymer dispersant UG-4030 (solid powder at room temperature, glass transition temperature 52 ° C.) manufactured by Toagosei Co., Ltd. as a polymer dispersant. 40% active ingredient) 37.5% by weight and 57.5% by weight of toluene, weighed in a paint shaker containing zirconia beads, and pulverized and dispersed for 6 hours. A fine particle dispersion (liquid A) was prepared.

  Here, when the dispersed particle diameter of the fine particles in the fine particle dispersion (liquid A) was measured by an apparatus based on the principle of dynamic light scattering (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.), it was 104 nm. . Next, the solution A was diluted with toluene to adjust the laser light absorber concentration to 0.001% by weight. The toluene diluted solution of the solution A was put in a glass cell having a thickness of 1 cm, and the transmittance was measured from ultraviolet to near infrared using a spectrophotometer (Hitachi Ltd. spectrophotometer U-4000). Assuming that the Lambert-Beer law holds in the toluene dilution of the A solution, the absorption coefficient ε in terms of weight concentration of TiN was determined at each wavelength using the following equation (1). The weight absorption coefficient ε plotted with respect to the wavelength in the visible / near infrared region is shown by a thick solid line in FIG.

ε = [log (100 / T)] / C (T:% transmittance at wavelength λ, C: concentration of laser light absorber in dispersion liquid g / L) (1)
As shown in FIG. 1, a large absorption band having a peak near a wavelength of 710 nm was observed in the titanium nitride TiN fine particles. Since the visible light portion is absorbed, the TiN fine particle dispersion has a deep purple to indigo color. From the absorption profile of FIG. 1, the TiN fine particle dispersion has a sufficiently large absorption coefficient of 30.61 L / gcm at a wavelength of 940 nm and 23.82 L / gcm at a wavelength of 1064 nm, and is 20 L / gcm or more over a wavelength range of 800 to 1130 nm. It has been confirmed that it is advantageous for absorbing laser light from an Nd: YAG laser having a wavelength of 1064 nm or a semiconductor laser having a wavelength of 800 to 1000 nm.

(Example 2)
The light-absorbing resin composition, which is a solid powder in which the liquid A according to Example 1 is heated to evaporate the toluene solvent component and 25% by weight of titanium nitride TiN fine particles are uniformly dispersed in the polymer dispersant. (B powder) was obtained. 9 parts by weight of this light-absorbing resin composition (B powder) and 1 part by weight of uncolored and transparent acrylic resin pellets are mixed, melt-kneaded at 280 ° C. using a twin-screw extruder, and the extruded strand is It was cut into pellets to obtain a light-absorbing component-containing master batch having a TiN fine particle concentration of 2.5% by weight.

  This master batch and acrylic resin pellets are filled into a blender, mixed uniformly, and then extruded to a thickness of 2.0 mm using a T-die. TiN fine particles are uniformly distributed throughout the resin at a concentration of 0.002% by weight. A plate 1 (light-absorbing resin molding), which is an acrylic resin test plate dispersed in, was prepared. The size of the plate 1 is 5 cm wide × 9 cm long.

Here, the content of the TiN fine particles contained in the plate 1 having a thickness of 2 mm is obtained by (volume of acrylic resin plate 1 m ² ) × (density of acrylic resin g / cm ³ ) × (weight fine particle concentration%). 100 cm × 100 cm × 0.2 cm × 1.2 g / cm ³ × 0.00002 = 0.048 g.

  Next, the optical characteristic of the said plate 1 was measured using the spectrophotometer (Hitachi Ltd. U-4000). As a result, as shown in FIG. 2, the visible light transmittance is 59%, and the transmittance at 940 nm is 56%. At the same time, the light of the semiconductor laser having a wavelength of 940 nm is sufficiently bright. It was found that it was absorbed.

  Next, a plate having the same size as that of the plate 1 but not containing TiN fine particles was prepared and used as a plate 2 (light-transmitting resin molded product).

  Here, the plate 1 containing TiN fine particles and the plate 2 not containing were superposed and brought into close contact with a crimping jig, and laser light was irradiated over 3 cm in the width direction (5 cm). The laser beam irradiation was performed using a fine device semiconductor laser (wavelength 940 nm) with an output of 30 W at a focal diameter of 1.2 mm and a scanning speed of 16 mm / s. With the irradiation of the laser beam, the plate 1 containing the light-absorbing fine particles was heated and melted, and further, the plate 2 was melted by the propagation of heat and fused together, and solidified by cooling to complete the joining. Even when the crimping jig was opened, the bonding was maintained.

  The appearance was visually observed, and it was evaluated that there was no color unevenness and the surface gloss was satisfactory.

  The jointed two plates were held with both hands, and the strength of the joint was estimated by applying a force to both ends of the plate downward and the center toward the top. It was found that the joint was firmly maintained even when a strong force was applied. Hereinafter, as shown in FIG. 2, as for the bonding strength, the case where the bonding is maintained even with a strong force is indicated as ○, the case where the bonding is peeled off with a light force but the bonding is peeled off, and the bonding itself is incomplete. XX was evaluated and displayed.

(Comparative Example 1)
In Example 1, instead of styrene / acrylic polymer dispersant UG-4030 (solid powder at room temperature, glass transition temperature 52 ° C.) manufactured by Toagosei Co., Ltd., a polymer dispersant that is liquid at room temperature A TiN fine particle dispersion according to Comparative Example 1 was prepared in the same manner as in Example 1 except that XG-4000 manufactured by Toagosei Co., Ltd. (with a glass transition temperature of −61 ° C.) was used. A TiN fine particle dispersion having a dispersed particle diameter of 121 nm was prepared. Next, this was heated to evaporate toluene, and a light-absorbing resin composition according to Comparative Example 3 in which 25% by weight of TiN fine particles were uniformly dispersed in the polymer dispersant was obtained. However, the light-absorbing resin composition according to Comparative Example 3 was sticky in a jelly form, and accurate weighing and mixing with clear pellets were difficult in the subsequent steps.

(Example 3)
A fine particle dispersion of zirconium nitride ZrN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 123 nm). Subsequently, the fine ZrN particles were obtained in the same manner as in Example 2. The dispersion was heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (ZrN). This light-absorbing resin composition was mixed with transparent pellets of acrylic resin, melt-kneaded with a twin-screw extruder, and extruded to obtain a master batch containing 2.5 wt% of light-absorbing fine particles (ZrN fine particles). . The melt kneading temperature was 280 ° C. This master batch was further diluted with the same clear acrylic resin pellets to produce plate 1 according to Example 3, which was an acrylic resin test plate in which ZrN fine particles were uniformly dispersed throughout the resin at a concentration of 0.002% by weight. (The plate 1 according to Example 3 has the same size as the plate 1 according to Example 2.)
About the plate 1 which concerns on the said Example 3, the transmission profile of 300-2600 nm was measured using the spectrophotometer, and the visible light transmittance | permeability and the transmittance | permeability in 940 nm were shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the content of the ZrN fine particles in the plate 1 (thickness 2 mm) is 0.048 g / m ² . The evaluation results are summarized in FIG.

  As is apparent from FIG. 2, when this light-absorbing resin molded product added with the zirconium nitride ZrN fine particles is used, the visible light transmittance is 62% and the transmittance at 940 nm is 58%, so that visible light is sufficiently transmitted. In addition, it is possible to perform laser welding with no problem in the appearance and strength of the joint portion, while maintaining beautiful and transparent transparency and maintaining beautiful surface gloss.

Example 4
A fine particle dispersion of hafnium nitride HfN (the dispersion particle size of the fine particles in the fine particle dispersion was 130 nm) was prepared in the same manner as in Example 1, and then the fine particles of HfN were prepared in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (HfN). This light-absorbing resin composition was mixed with transparent pellets of polycarbonate resin, melt-kneaded with a twin screw extruder, and extruded to obtain a master batch containing 2.5% by weight of light-absorbing fine particles (HfN fine particles). . The melt kneading temperature was 280 ° C. This master batch was further diluted with the same clear polycarbonate resin pellets to prepare plate 1 according to Example 4, which is a polycarbonate resin test plate in which HfN fine particles were uniformly dispersed throughout the resin at a concentration of 0.002% by weight.

The plate 1 according to Example 4 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the HfN fine particle content of the plate 1 (thickness 2 mm) is 0.048 g / m ² . The evaluation results are summarized in FIG.

  As is apparent from FIG. 2, when the light-absorbing resin molded product to which the hafnium nitride HfN fine particles are added is used, the visible light transmittance is 58% and the transmittance at 940 nm is 55%. In addition, it is possible to perform laser welding with no problem in the appearance and strength of the joint portion, while maintaining beautiful and transparent transparency and maintaining beautiful surface gloss.

(Example 5)
A fine particle dispersion of tantalum nitride TaN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 196 nm). Subsequently, the fine particles of TaN were prepared in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (TaN). This light-absorbing resin composition was mixed with transparent pellets of polycarbonate resin, melt-kneaded with a twin-screw extruder, and extruded to obtain a master batch containing 2.5 wt% of light-absorbing fine particles (TaN fine particles). . The melt kneading temperature was 280 ° C. This master batch was further diluted with the same clear polycarbonate resin pellets to produce Plate 1 according to Example 5, which was a polycarbonate resin test plate in which TaN fine particles were uniformly dispersed throughout the resin at a concentration of 0.0025% by weight.

The plate 1 according to Example 5 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the content of TaN fine particles in the plate 1 (thickness 2 mm) is 0.061 g / m ² . The evaluation results are summarized in FIG.

  As is apparent from FIG. 2, when the light-absorbing resin molded product to which the tantalum nitride TaN fine particles are added is used, the visible light transmittance is 50%, and the transmittance at 940 nm is 47%. In addition, it is possible to perform laser welding with no problem in the appearance and strength of the joint portion, while maintaining beautiful and transparent transparency and maintaining beautiful surface gloss.

(Example 6)
A fine particle dispersion of titanium nitride TiN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 112 nm). Subsequently, the fine particles of TiN were prepared in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (TiN). This light-absorbing resin composition is mixed with transparent pellets of polyethylene terephthalate resin, melt-kneaded with a twin screw extruder, and extruded to obtain a masterbatch containing 2.5% by weight of light-absorbing fine particles (TiN fine particles). It was. The master batch was further diluted with the same clear polyethylene terephthalate resin pellets, and the plate 1 according to Example 6, which is a polyethylene terephthalate resin test plate in which TiN fine particles were uniformly dispersed throughout the resin at a concentration of 0.004% by weight, was obtained. Produced.

The plate 1 according to Example 6 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the TiN fine particle content of the plate 1 (thickness 2 mm) is 0.096 g / m ² . The evaluation results are summarized in FIG.
As can be seen from FIG. 2, when the light-absorbing resin molding based on polyethylene terephthalate to which the TiN fine particles are added is used, the visible light transmittance is 39% and the transmittance at 940 nm is 34%. Therefore, it is possible to perform laser welding with no problem in the appearance and strength of the bonded portion, while maintaining beautiful transparency while maintaining transparency.

(Example 7)
In the same manner as in Example 1, a fine particle dispersion of niobium nitride NbN (dispersed particle size of fine particles in the fine particle dispersion was 225 nm) was prepared. Subsequently, in the same manner as in Example 2, NbN fine particles The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (NbN). This light-absorbing resin composition was mixed with transparent pellets of polystyrene resin, melt-kneaded with a twin screw extruder, and extruded to obtain a masterbatch containing 2.5 wt% of light-absorbing fine particles (NbN fine particles). . This master batch was further diluted with the same clear polystyrene resin pellets to produce plate 1 according to Example 7, which was a polystyrene resin test plate in which NbN fine particles were uniformly dispersed throughout the resin at a concentration of 0.0068% by weight. .

The plate 1 according to Example 7 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the NbN fine particle content of the plate 1 (thickness 2 mm) is 0.163 g / m ² . The evaluation results are summarized in FIG.

  As can be seen from FIG. 2, when this polystyrene-based light-absorbing resin molding added with NbN fine particles is used, the visible light transmittance is 25%, and the transmittance at 940 nm is 24%. While maintaining transparency, beautiful welding is performed while maintaining surface gloss, and laser welding can be performed with no problem in the appearance and strength of the joint.

(Example 8)
A fine particle dispersion of titanium nitride TiN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 139 nm). Subsequently, TiN fine particles were obtained in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (TiN). This light-absorbing resin composition was mixed with transparent pellets of polyamide resin, melt-kneaded with a twin-screw extruder, and extruded to obtain a master batch containing 2.5 wt% of light-absorbing fine particles (TiN fine particles). . This master batch was further diluted with the same clear polyamide resin pellets to produce plate 1 according to Example 8, which was a polyamide resin test plate in which TiN fine particles were uniformly dispersed throughout the resin at a concentration of 0.001% by weight. .

The plate 1 according to Example 8 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the TiN fine particle content of the plate 1 (thickness 2 mm) is 0.024 g / m ² . The evaluation results are summarized in FIG.

  As can be seen from FIG. 2, when the light-absorbing resin molding based on polyethylene terephthalate to which the TiN fine particles are added is used, the visible light transmittance is 73%, and the transmittance at 940 nm is 69%. It is possible to perform laser welding without causing any problems in the appearance and strength of the bonded portion, while maintaining beautiful transparency while maintaining the bright transparency.

Example 9
A fine particle dispersion of titanium nitride TiN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 160 nm), and subsequently, fine particles of TiN were obtained in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (TiN). This light-absorbing resin composition was mixed with transparent pellets of polyethylene resin, melt-kneaded with a twin screw extruder, and extruded to obtain a master batch containing 2.5% by weight of light-absorbing fine particles (TiN fine particles). . This master batch was further diluted with the same clear polyethylene resin pellets, and a plate 1 according to Example 9 which was a polyethylene resin test plate in which TiN fine particles were uniformly dispersed throughout the resin at a concentration of 0.0021% by weight was produced. . Although this plate 1 transmitted light sufficiently, it was slightly cloudy.

The plate 1 according to Example 9 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the TiN fine particle content of the plate 1 (thickness 2 mm) is 0.050 g / m ² . The evaluation results are summarized in FIG.

  As can be seen from FIG. 2, when the polyethylene-based light-absorbing resin molded product to which TiN fine particles are added is used, the visible light transmittance is 53% and the transmittance at 940 nm is 55%. As a result, it is possible to perform beautiful laser welding with maintaining the surface gloss while maintaining bright transparency, and it is possible to perform laser welding with no problem in the appearance and strength of the joint.

(Example 10)
A fine particle dispersion of titanium nitride TiN was prepared in the same manner as in Example 1 (the dispersed particle diameter of the fine particles in the fine particle dispersion was 128 nm), and subsequently, fine particles of TiN were obtained in the same manner as in Example 2. The dispersion is heated to evaporate the toluene solvent component to obtain a light-absorbing resin composition containing 25% by weight of the fine particle component (TiN). This light-absorbing resin composition is mixed with transparent pellets of ethylene-tetrafluoroethylene copolymer resin, melt-kneaded with a twin-screw extruder, and extruded to give 2.5 parts by weight of light-absorbing fine particles (TiN fine particles). % Containing a master batch. This master batch was further diluted with the same clear ethylene-4 fluoroethylene copolymer resin pellets, and ethylene-4 fluoroethylene copolymer with TiN fine particles uniformly dispersed throughout the resin at a concentration of 0.0037% by weight. A plate 1 according to Example 10 which is a united resin test plate was produced.

The plate 1 according to Example 10 was measured for a transmission profile of 300 to 2600 nm using a spectrophotometer, and the visible light transmittance and the transmittance at 940 nm are shown in FIG. Furthermore, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, were brought into close contact with each other and irradiated with semiconductor laser light. In this case, the TiN fine particle content of the plate 1 (thickness 2 mm) is 0.088 g / m ² . The evaluation results are summarized in FIG.

As is apparent from FIG. 2, when the light-absorbing resin molding based on ethylene-4 fluoroethylene copolymer resin added with the TiN fine particles is used, the visible light transmittance is 44%, and the transmittance at 940 nm is 39%. It is possible to perform laser welding with no problem in the appearance and strength of the joint, because beautiful welding is performed while maintaining the surface gloss while maintaining sufficient transparency by passing visible light sufficiently. .
(Example 11)
In the same manner as in Example 1, a TiN fine particle dispersion (solution C) containing 5% by weight of titanium nitride TiN fine particles, 25% by weight of a polymeric dispersant, and 70% by weight of toluene was prepared. The dispersed particle diameter of the fine particles in the fine particle dispersion was 118 nm. 23% by weight of this dispersion and 77% by weight of an ultraviolet curable resin for hard coat (UV-3701 manufactured by Toagosei Co., Ltd., solid content: 100%) were mixed to prepare a coating liquid. This coating solution was applied and formed on a 3 mm thick acrylic resin plate substrate using a bar coater. The acrylic substrate was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp, to produce the plate 1 according to Example 11 which was an acrylic substrate with a coating film.

The coating film thickness of the plate 1 according to Example 11 was measured to be 5 μm with a stylus type film thickness meter. From the solid content ratio, the fine particle concentration in this film is 1.48% by weight, and the content of TiN fine particles over a thickness of 5 μm is 0.09 g / m ² . When the optical characteristics of the plate 1 according to Example 11 were measured, it was found that the visible light transmittance was 46% and the light in the visible light region was sufficiently transmitted. Further, the plate 1 and the plate 2 (which is the same size as the plate 2 described in Example 2), which is a resin test plate not containing light-absorbing fine particles, are brought into close contact with each other via the coating surface of the plate 1. Irradiated with semiconductor laser light. The evaluation results are summarized in FIG.

  As is apparent from FIG. 2, when the light-absorbing resin molding coated with the TiN fine particles is used, the visible light transmittance is 46%, and the transmittance at 940 nm is 39%. Beautiful welding with maintaining surface gloss is made while maintaining the properties, and it becomes possible to perform laser welding with no problem in the appearance and strength of the joint.

(Comparative Example 2)
Sumitomo Metal Mining Co., Ltd. ITO fine particles 20 wt%, polymer dispersant 35 wt%, toluene 45 wt% are weighed and filled in a paint shaker containing zirconia beads for 6 hours pulverization / dispersion treatment By doing so, a fine particle dispersion of ITO was prepared. The dispersion particle diameter of the ITO fine particle dispersion was 140 nm.
The ITO fine particle dispersion was diluted with toluene to a laser light absorber concentration of 0.1% by weight, and the weight absorption coefficient was determined in the same manner as in Example 1 and is shown by a thin broken line in FIG. As is apparent from the profile of FIG. 1, the ITO fine particle dispersion according to Comparative Example 2 has a characteristic of absorbing a long near-infrared wavelength from a wavelength of about 1000 nm, and can be absorbed by an Nd: YAG laser having a wavelength of 1064 nm. You can see that there is sex.
However, the weight absorption coefficient of the ITO fine particles according to Comparative Example 2 is very small at about 0.35 L / gcm at a wavelength of 1064 nm. The weight absorption coefficient of titanium nitride TiN at a wavelength of 1064 nm was 23.8 L / gcm, and it was found that ITO had only about 1/68 of the effect of TiN. In the region related to the semiconductor laser having a wavelength of 800 to 1000 nm, this difference is even greater. The weight absorption coefficient at a wavelength of 940 nm has a value of 30.6 L / gcm, which is 161 times that of TiN, compared to 0.19 L / gcm of ITO. Therefore, when the ITO fine particles according to Comparative Example 2 are used to obtain the same effect as the fine particles according to Examples 1 to 11, two to three orders of magnitude or more are obtained as compared with the fine particles according to Examples 1 to 11. It has been found that it is necessary to use a large amount of ITO fine particles.

By using the prepared ITO toluene dispersion, the same procedure as in Example 2 was followed to prepare an acrylic resin test plate 1 containing 0.017% by weight of ITO. The ITO fine particle content of the plate 1 (thickness 2 mm) at this time was 0.4 g / m ² which is the upper limit of the content of nitride fine particles of this patent. Although the content of ITO fine particles was the highest as compared with the nitride fine particles shown in Examples 2 to 11, the 940 nm transmittance was 87%.

Both the acrylic resin test plate 1 containing 0.017% by weight of ITO and the plate 2 which is a resin test plate not containing ITO fine particles (the same size as the plate 2 described in Example 2) are used together. It was made to adhere and it irradiated with the semiconductor laser beam. In this case, welding did not occur at all by laser light irradiation.

(Comparative Example 3)
Sumitomo Metal Mining Co., Ltd. 20% by weight of ATO fine particles, 35% by weight of polymeric dispersant and 45% by weight of toluene are weighed and filled in a paint shaker containing zirconia beads and pulverized and dispersed for 6 hours. By doing so, a fine particle dispersion of ITO was prepared. Of the ATO
The dispersed particle size of the fine particle dispersion was 117 nm.
The ATO fine particle dispersion was diluted with toluene to a laser light absorber concentration of 0.1% by weight, and the weight absorption coefficient was determined in the same manner as in Example 1 and is shown by the thin broken line in FIG. As apparent from the profile of FIG. 1, the ATO fine particle dispersion according to Comparative Example 3 has a characteristic of absorbing a long near-infrared wavelength from a wavelength of about 1000 nm, and can absorb an Nd: YAG laser having a wavelength of 1064 nm. You can see that there is sex. However, the weight absorption coefficient of the ATO fine particles according to Comparative Example 3 is as small as about 0.57 L / gcm at a wavelength of 1064 nm. The weight absorption coefficient of titanium nitride TiN at a wavelength of 1064 nm was 23.8 L / gcm, and ATO was found to have only about 1/42 of the effect of TiN. In the region related to the semiconductor laser having a wavelength of 800 to 1000 nm, this difference is even greater. The weight absorption coefficient at a wavelength of 940 nm has a value of 30.6 L / gcm which is 80 times that of TiN compared to 0.38 L / gcm of ATO. Therefore, when the ATO fine particles according to Comparative Example 3 are used to obtain the same effect as the fine particles according to Examples 1 to 11, an amount of ATO that is about two orders of magnitude higher than the fine particles according to Examples 1 to 9 is used. It was found that it was necessary to use fine particles.

Using the produced ATO toluene dispersion, the same procedure as in Example 2 was followed to produce Plate 1 which was an acrylic resin test plate containing 0.017% by weight of ATO. The ITO fine particle content of the plate 1 (thickness 2 mm) at this time was 0.4 g / m ² which is the upper limit of the content of nitride fine particles of this patent. Although the ATO fine particle content was the highest as compared with the nitride fine particles shown in Examples 2 to 11, the 940 nm transmittance was 88%.

  Both the acrylic resin test plate 1 containing 0.017% by weight of this ATO and the plate 2 which is a resin test plate containing no ATO fine particles (the same size as the plate 2 described in Example 2). It was made to adhere and it irradiated with the semiconductor laser beam. In this case, welding did not occur at all by laser light irradiation.

(Comparative Example 4)
The titanium nitride TiN fine particles were pulverized very simply for 5 minutes by a paint shaker and subjected to dispersion treatment, and the particle diameter was measured to be 1100 nm. Using this TiN fine particle dispersion, a plate 1 according to Comparative Example 4, which is an acrylic resin plate containing 0.048% by weight of TiN fine particles, was produced in the same process as in Example 2.

Since the plate 1 according to Comparative Example 4 had an excessively large particle size, there was almost no absorption in the near-infrared region, and the transmittance at 940 nm was 77% with respect to the visible light transmittance of 56%. The content of the TiN fine particles in the 1 mm-thick portion of the plate 1 according to Comparative Example 6 is 1.2 g / m ² .

  The acrylic resin test plate containing 0.1% by weight of the TiN fine particles and the plate 2 which is a resin test plate not containing the TiN fine particles (the same size as the plate 2 described in Example 2) are adhered to each other. Then, a semiconductor laser beam was irradiated. In this case, although welding occurred by laser light irradiation, it was found that the bonding strength was weak and the two plates could be easily peeled off.

(Comparative Example 5)
Plate 1 according to Comparative Example 5 which is an acrylic resin plate containing TiN fine particles at a high concentration of 0.025 wt% using the light-absorbing resin composition (B powder) containing TiN fine particles obtained in Example 2 Was made.

The content of TiN fine particles in the plate 1 (thickness 2 mm) according to Comparative Example 5 is 0.60 g / m ² . This plate is almost black and hardly transmits visible light, indicating that it cannot be used as a transparent laser light absorbing resin.

  An acrylic resin test plate 1 containing 0.025% by weight of the TiN fine particles and a plate 2 that is a resin test plate not containing TiN fine particles (the same size as the plate 2 described in Example 2). It was made to adhere and it irradiated with the semiconductor laser beam. In this case, heat generation and dissolution due to the laser beam were excessive, foaming was seen on one side along the laser-scanned region, and the appearance was poor.

(Comparative Example 6)
TiN fine particles produced by the thermal plasma method are mixed with a clear acrylic resin pellet and a blender as it is without being wet-dispersed, melted and kneaded with a twin screw extruder, and the extruded strand is cut into a pellet. An acrylic resin master batch containing 2.5% by weight of TiN fine particles was obtained. This was further diluted with a clear pellet to prepare a plate 1 according to Comparative Example 6 which is an acrylic resin test plate containing 0.002 wt% of TiN fine particles.

The content of TiN fine particles in the plate 1 (thickness 2 mm) according to Comparative Example 6 is 0.048 g / m ² . The plate 1 was observed to have uneven color shading.

  An acrylic resin test plate 1 containing 0.002% by weight of the TiN fine particles and a plate 2 that is a resin test plate not containing TiN fine particles (the same size as the plate 2 described in Example 2). Both were closely adhered and irradiated with a semiconductor laser beam. In this case, the welding was performed by laser irradiation, but the bonding strength was weaker than usual and the result was easily peeled off.

It is a graph which shows the relationship between the weight absorption coefficient of each fine particle dispersion of TiN, ITO, and ATO, and the wavelength of light (300 nm-2100 nm). It is a graph which shows the composition outline | summary of the light absorption resin molding which concerns on Examples 2-11 and Comparative Examples 2-6, and its characteristic.

Claims (8)

A laser-absorbing light-absorbing resin composition comprising a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser-absorbing fine particles,
The laser-welding light-absorbing resin composition, wherein the laser-light-absorbing fine particles are at least one kind of nitride fine particles selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride .   2. The light-absorbing resin composition for laser welding according to claim 1, wherein the nitride fine particles have an average particle size of 1000 nm or less. 3. A laser-welding light-absorbing resin composition according to claim 1, wherein the laser-welding light-absorbing resin composition is diluted with a polymer dispersant and a thermoplastic resin contained in the laser-welding light-absorbing resin composition and kneaded and molded. A light-absorbing resin molded body,
The surface layer of the light-absorbing resin molded body, wherein the content of the vaginalized fine particles in a region 3 mm or less from the surface is 0.001 g / m ² or more and 0.4 g / m ² or less. Light-absorbing resin molding. 3. A laser-welding light-absorbing resin composition according to claim 1, wherein the laser-welding light-absorbing resin composition is diluted with a polymer dispersant and a thermoplastic resin contained in the laser-welding light-absorbing resin composition and kneaded and molded. A light-absorbing resin molded body,
The light-absorbing resin molded body according to claim 3, wherein the shape of the molded light-absorbing resin molded body is a plate shape or a film shape.   The thermoplastic resin is at least one selected from the group consisting of acrylic resin, polycarbonate resin, styrene resin, low density polyethylene resin, polypropylene resin, polyurethane resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and fluororesin. The light-absorbing resin molded article according to claim 3 or 4, wherein the molded article is a resin.   3. A light-absorbing resin molded article, wherein the light-absorbing resin composition according to claim 1 is diluted with a binder and coated on the surface of a substrate.   The light-absorbing resin molded body according to any one of claims 3 to 6, wherein the light-absorbing resin molded body has an absorption maximum at a wavelength of 500 to 1000 nm. Polymer dispersion in which a laser welding light absorbing resin composition containing a polymer dispersant having a glass transition temperature of 30 ° C. or higher and laser light absorbing fine particles is contained in the laser welding light absorbing resin composition A method for producing a light-absorbing resin molded article that is diluted and kneaded with an agent and a thermoplastic resin,
A light-absorbing resin composition in which the laser light-absorbing fine particles are at least one kind of nitride fine particles selected from titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, and tantalum nitride; Using a thermoplastic resin, the content of the nitride fine particles in the surface layer of the light-absorbing resin molded body, which is 3 mm or less from the surface, is 0.001 g / m ² or more and 0.4 g / m ² or less. The method for producing a light-absorbing resin molded body is characterized in that a light-absorbing resin molded body is produced by diluting, kneading and molding so as to be.

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