JP2008208247A - Resin or resin composition for laser welding use, and molded form using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin material or resin composition capable of forming a firm joint by laser welding, and to provide a molded form joined by laser welding using the resin or resin composition. <P>SOLUTION: The resin for laser welding use is provided, being 35 mN/m or greater in surface free energy, 150°C or higher in melting point and 20°C or higher in glass transition temperature. The resin contains, in its structure, either one kind of linkage component such as an imino group, amido group, ester group, urethane group, imido group, ether group, carbonate group or urea group, or an ionic group or reactive group such as a carboxylic acid group, hydroxy group, metal sulfonate group, amine group, glycidyl group, silanol group, carbodiimido group or isocyanate group. The resin composition for laser welding use comprises the above resin and, optionally, one or more ingredients among a heteroresin, reinforcing fiber, foaming agent, coloring material, filler and stabilizer. The molded form joined by laser welding using the above resin or resin composition is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin and a resin composition suitable for laser welding of a resin material and a resin material, a resin material and a metal material, a resin material and glass, a resin material and ceramic, or the like. Moreover, this invention relates to the molded object for laser joining obtained from these resin and resin composition.

  As a conventional method used for joining a resin material and a resin material, and joining a metal material, glass, ceramic, and a resin material, there are a method using rivet fastening and an adhesive. Adhesion is a method in which a metal material and a resin material are fixed by an adhesive with a physical adsorption force and a chemical adsorption force. On the other hand, rivet fastening is a physical fastening method in which a rivet having a diameter of several millimeters to several tens of millimeters is driven and fixed so as to penetrate a metal material and a resin material.

  However, the field of application is currently limited in methods using adhesives and rivet fastening. Bonding does not increase in size or mass, but technically, it is difficult to bond pinpoints precisely because the adhesive spreads wet, and adhesive strength is higher on uneven surfaces than on flat surfaces. In terms of limitation of the adhesive surface and production, there are problems such as a decrease in production tact and difficulty in maintaining and managing the state of the adhesive due to a long curing time. Since rivet fastening has a certain size and mass at the fastening part, it is inevitable to increase the size and weight of the part, and the degree of freedom in design is reduced, so it is mainly applied to large or simple products or parts. ing. On the other hand, there is a strong demand for simply joining a resin material and a resin material, or a resin material and a different material. The reason is that the resin material is used only in the necessary part and the rest is replaced with another resin material or a different material, and various merits such as the creation of a new composite functional material having the characteristics of various materials can be mentioned. . For example, when a part of a conventional metal material is changed to a resin material, since the cost of the resin material is less than half that of the metal material, a significant cost reduction can be expected. On the other hand, when a part of the resin material is changed to a metal material, it is possible to impart characteristics such as heat dissipation. In joining at that time, it is preferable that a suitable amount can be joined to a suitable place.

  In joining using a laser, a method of joining by welding or welding metal materials or the same kind of resins is put into practical use, but a resin material different from a resin material, or a resin material and metal, glass, ceramic, etc. The dissimilar materials are not joined. However, in recent years, laser resin bonding is an epoch-making process in which a transparent material and an opaque material are superposed on the wavelength of the laser beam, and the laser beam is irradiated from the transparent material side to melt and bond only the joint. Have been put to practical use. In this method, a large bonding area can be obtained, and generation of gas based on decomposition of the resin during heating can be suppressed (see Patent Documents 1 to 3 and Non-Patent Document 1).

  In welding or welding using lasers between metal materials or the same type of resin, the laser is only used as a heat source, and bonding is only due to the mutual diffusion of metal and resin between the same type of materials. No special technique is required for welding. On the other hand, in the bonding between resin materials different from resin materials and the bonding of resin materials to dissimilar materials such as metal, glass, and ceramic, such techniques are required in spite of the necessity of special techniques from the viewpoint of resin and processing. No technology has been reported.

  The present invention was devised in view of the problems of the prior art, and its purpose is not limited in the application field, and a resin material and a resin composition capable of forming a strong joint by laser welding, It is providing the molded object joined by laser welding using resin and a resin composition.

JP 2003-325710 A JP-A-60-214931 JP 2002-67165 A Proceedings of the 59th Laser Processing Society, pp. 1-7 (September 2003)

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following means, and have reached the present invention. That is, this invention consists of the structure of following (1)-(6).
(1) Laser welding resin having a surface free energy of 35 mN / m or more (2) Laser welding resin having a melting point of 150 ° C. or higher (3) Glass transition temperature of 20 ° C. or higher (1) The resin for laser welding (4) In any one of the main chain, side chain and / or terminal of the resin of (1) to (3), an imino group, an amide group, an ester group, a urethane group in the resin structure Bonding components such as imide group, ether group, carbonate group, urea group or ionic groups such as carboxylic acid, hydroxyl group, sulfonic acid metal base, amine group, glycidyl group, silanol group, carbodiimide group, isocyanate group or reactivity A laser welding resin comprising any one of groups.
(5) In any one of the resins of (1) to (4), a different resin, a reinforcing fiber, a foaming agent, a colorant, a filler, a foaming agent, a stabilizer strong fiber, a colorant, a filler, a foaming agent, a stabilizer, The resin composition for lasers containing any one or more among these.
(6) The laser welding resin and resin composition according to any one of (1) to (5), which are foamed by a laser.
(7) A molded article for laser bonding obtained from the laser welding resin or resin composition of (1) to (6).

When joining resin materials and dissimilar materials, or resin materials and metal materials, glass, or ceramics, special interaction must occur at the interface during laser welding, so the resin material is covalently bonded to the interface. And a functional group capable of forming a strong bond such as a hydrogen bond or an ionic bond. Specifically, when the surface free energy of the resin material is 35 mN / m or more, strong bonding is possible. More preferably, the melting point is 150 ° C. or higher or the glass transition temperature is 20 ° C. or higher. If the material is amorphous and has a glass transition point of less than 20 ° C. at room temperature, it is difficult to obtain a good appearance when the resin flows out greatly during laser welding. Furthermore, a resin composition in which a filler or glass fiber for adjusting the thermal expansion coefficient, a foaming agent for promoting foaming, a rubber component for relaxing residual stress at the interface, or the like is compounded to the resin material. It is preferable to use it.
In the joining, it is most preferable to heat the resin materials in the joined portion to the extent that the vaporized or thermally decomposed gas swells from the inside of the resin material and generates bubbles in the inside of the resin in a state where the materials are combined. At this time, although it is a micro-sized region, explosive pressure accompanying the generation of bubbles is applied to the joint, and the temperature of the resin material at the joint is high, and the resin material and adherend around the bubble The materials meet the conditions that enable physical bonding such as anchor effect, and chemical bonding through covalent bonds, hydrogen bonds, and ionic bonds. Further, when the resin material cools and hardens, the temperature of the bubbles also decreases, so that the pressure inside the bubbles is reduced and an adsorption force is also generated. It becomes possible to bond a metal or the like to a resin in a form in which these bonding forces are combined. Furthermore, by using laser light as a heating source, local rapid heating and rapid cooling are possible, pressure and adsorption force associated with bubble generation can be increased, and material joining can be promoted. Can do. Therefore, a resin or resin composition that foams upon laser irradiation is preferred. A molded body joined by laser welding of such a resin and a resin composition exhibits excellent adhesive strength, adhesion durability, and interface confidentiality.

  The laser welding resin of the present invention enables the resin material to be strongly bonded to a different resin material, a metal material, a glass material, or a ceramic material. Specifically, by providing a structure having a surface free energy of 35 mN / m or more of the resin material, strong bonds such as covalent bonds, hydrogen bonds, and ionic bonds are generated at the interface with the adherend during laser welding, and the resin material is strong. Can be promoted. Furthermore, laser welding by adding different types of resin, reinforcing fiber, foaming agent, colorant, filler, foaming agent, stabilizer long fiber, filler, foaming material, stabilizer, etc., or foaming inside the resin during laser irradiation Bonding by is further improved. The molded body of the present invention can be provided as automotive interior / exterior parts, electrical parts, electronic material parts, building material parts, household goods, office supplies, medical parts, industrial material goods, clothing goods, etc. It is useful industrially.

  Moreover, many advantages are generated by using a laser light source or an ionizing radiation source as a heating source. First, laser light sources, ionizing radiation sources, and the like can be locally heated, so that small joints can be created. Therefore, a rivet-sized joint part and rivet itself in rivet fastening are not necessary, and an increase in the size and mass of the joint part can be prevented. Second, in the bonding method using an adhesive, it is difficult to bond a pinpoint precisely because the adhesive spreads wet, but for example, a laser light source can reduce the beam diameter to the micron order, so a precise and fine bonding part is also available. Is possible. Third, since the adsorption force generated when the resin material cools and hardens works more favorably on a flat surface, it is possible to reduce the limitation of the bonding surface. Fourth, the laser beam irradiation time required for bonding is shorter than the time required for curing the adhesive, and does not become a process for limiting production. In addition, when joining with a laser beam, it may be possible to suppress the occurrence of oxidation / deterioration than when joining with an adhesive, and maintenance and management are relatively easy. Fifth, by selecting the wavelength of the laser light that passes through the resin material and the ionizing radiation source, it is possible to heat from the metal material, glass material, or ceramic material side as well as the resin material side. There is no restriction on the direction of the source. This increases the degree of freedom of design and material selection, and is very effective in terms of production technology. In fact, there are cases where there is a restriction that laser light can be irradiated only from one side in joining of resin materials using laser light.

As the resin of the present invention, it is necessary to use a resin having a surface free energy of 35 mN / m or more, more preferably 40 mN / m or more, and most preferably 45 mN / m or more. When the surface free energy is less than 35 mN / m, the resin has few sites for hydrogen bonding or ionic bonding, and there are no sites for interaction with different types of resin adherends. In the case of ceramic, adhesion failure occurs due to a significant decrease in wettability. The surface free energy shown here refers to a value obtained from contact angle measurement. Using water and methylene iodide as droplet components for contact angle measurement, calculate γsd and γsp from γl (1 + COSθ) = 2 (γsd · γld) ^0.5 + 2 (γsp · γlp) ^0.5, and the surface of the resin from γs = γsd + γsp Free energy can be obtained. Where θ is the contact angle, γsd is the dispersion component in the surface free energy of the resin, γsp is the polar component in the surface free energy of the resin, γl is the surface free energy of the liquid component, and γld is in the surface free energy of the liquid component. The dispersion component γlp is a polar component in the surface free energy of the liquid component.

  The resin of the present invention preferably has a melting point of 150 ° C. or higher or a glass transition point of 20 ° C. or higher. If the melting point is less than 150 ° C and the glass transition point is less than 20 ° C, the resin will flow easily during laser irradiation and it will be difficult not only to obtain a good appearance, but it can also be easily bonded by heat sealing. Therefore, the advantage of using laser welding is reduced. In the case of irradiating a laser from a resin component, an amorphous resin, a low crystalline resin, or a crystalline resin composed of a microcrystalline size is preferable because of its high transparency to the laser. The melting point and glass transition point described here refer to the melting peak temperature and the inflection point temperature of specific heat that appear when a sufficiently heat-treated resin is heated from a low temperature at 20 ° C./min using DSC.

The resin of the present invention preferably has a polar group or a group reactive with a resin, metal, glass, or ceramic as an adherend in the side chain and / or terminal. Such a functional group is not limited to the following, but in particular at any one of the main chain, side chain and / or terminal, imino group, amide group, ester group, urethane group, imide group, ether group, thioether group, carbonate group , Urea group, or any one of carboxylic acid, hydroxyl group, sulfonic acid metal base, polar group such as amine group, glycidyl group, silanol group, carbodiimide group, isocyanate group, ionic group or reactive group It is preferable. For example, a polyamide resin represented by nylon 6 or nylon 66, a polyester resin represented by polyethylene terephthalate or polybutylene terephthalate, a polycarbonate resin, an acrylic resin represented by polymethyl methacrylate or polyacrylic acid Polyimide resin, polyamide imide resin, polyphenylene sulfide resin, polyurethane resin, styrene resin thermoplastic resin, such as “Kapton” manufactured by DuPont Co., Ltd. and Ube Industries “Upilex”, and these thermoplastic resins as epoxy resins And resins modified with silane coupling agents, thermosetting resins such as epoxy resins, unsaturated polyester resins, melamine resins, urea resins, polycarbodiimide resins, and modified resins. Among these, polyester resins, polyamide resins, polycarbonate resins, polyimide resins, polyamideimide resins, and polyphenylene sulfide resins that are used as engineering plastics and super engineering plastics are preferable. As specific constituent components of the polyester, polyvalent carboxylic acids shown below, alkyl esters thereof, or acid anhydrides can be used. Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and 2,2′-diphenyl. Aromatic dicarboxylic acids such as dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 5-sulfonic acid sodium isophthalic acid, 5-hydroxyisophthalic acid, fumaric acid, maleic acid, succinic acid, itaconic acid, adipic acid, azelaic acid, Sebacic acid, 1,12-dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid, etc. Aliphatic and alicyclic dicarboxylic acids, trimellitic acid, pyromellitic acid Acid, benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, ethylene glycol bis (anhydrotrimellitate), and aromatic polycarboxylic acids, such as glycerol tris (anhydrotrimellitate) and the like. Examples of the polyol component of the polyester include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3. -Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, dipropylene glycol 2,2,4-trimethyl-1,5-pentanediol, neopentylhydroxypivalate, bisphenol A ethylene oxide adduct and propylene oxide adduct, hydrogenated bisphenol A ethylene oxide adduct And propylene oxide adduct, 1,9- Nandiol, 2-methyloctanediol, 1,10-decanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, dimer diol, polycarbonate glycol, Examples thereof include glycerin, trimethylolpropane, pentaerythritol, dimethylolbutanoic acid, dimethylolpropionic acid, polycarbonate diol, and polyether glycol. Polyether glycols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and copolymers thereof. Furthermore, diols such as neopentyl glycol and bisphenol A, diphenols, and the like are co-polymerized with these alkylene glycols. Polymerized products also apply. The number average molecular weight of the polyether glycol is preferably 400 to 10,000. A preferred lower limit is 600, more preferably 800. Furthermore, lactones such as ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, β-propiolactone, γ-butyrolactone, lactic acid, glycolic acid, 2-hydroxyisobutanoic acid, 3-hydroxybutane Examples thereof include hydroxycarboxylic acids such as acid, 4-hydroxybutanoic acid and 6-hydroxycaproic acid and cyclic dimers thereof. Among them, polyarylate, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and other crystalline polyesters, these are copolymerized with cyclohexanedimethanol, neopentyl glycol, isophthalic acid, etc. A resin whose crystallinity is lowered or amorphous is preferred.
As the amine component of polyamide, ethylenediamine, trimethylenediamine, tetramethylenediamine, bentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, Tridecamethylenediamine, hexadecamethylenediamine, octadecamethylenediamine, aliphatic diamines such as 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, cyclohexanediamine, methylcyclohexanediamine, bis- ( 4,4'-aminocyclohexyl) methane, cycloaliphatic diamines such as isophoronediamine, metaxylylenediamine, paraxylylenediamine, paraphenylenediamine, metaphenyle Aromatic diamines and like these hydrogenated products such as an aromatic diamine such as diamines. As the acid component of the polyamide, the following polyvalent carboxylic acids or acid anhydrides can be used. Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and 2,2′-diphenyl. Aromatic dicarboxylic acids such as dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 5-sulfonic acid sodium isophthalic acid, 5-hydroxyisophthalic acid, fumaric acid, maleic acid, succinic acid, itaconic acid, adipic acid, azelaic acid, Sebacic acid, 1,12-dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid, etc. Aliphatic and alicyclic dicarboxylic acids, trimellitic acid, pyromellitic acid Acid, benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, ethylene glycol bis (anhydrotrimellitate), and aromatic polycarboxylic acids, such as glycerol tris (anhydrotrimellitate) and the like. Moreover, lactams, such as epsilon caprolactam, aminocarboxylic acid, etc. are mention | raise | lifted. In particular, polycaproamide (nylon 6), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyun Decamethylene adipamide (nylon 116), polymetaxylylene adipamide (nylon MXD6), polyhexamethylene sebamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyhexamethylene terephthalamide (nylon 6T ), Polyhexamethylene isophthalamide (nylon 6I), polynonamethylene terephthalamide (nylon 9T), polyundecamethylene terephthalamide (nylon 11T), polyundecamethylene hexahydroterephthalamide (Niro) 11T (H)), polybis (3-methyl-4-aminohexyl) methane dodecanamide (nylon PACM12), polybis (3-methyl-4-aminohexyl) methane dodecanamide (nylon PACM12), Tg of 100 ° C. or higher Transparent nylon, copolymerized polyamides thereof, mixed polyamides and the like are preferable.

In addition, you may use for the resin material in this invention what added different resin, a reinforcing fiber, a foaming agent, a coloring material, a filler, a stabilizer, etc. As the dissimilar resin, not only the resin typified above having a surface free energy of 35 mN / m or more, but also a resin having a surface free energy of less than 35 mN / m can be used. Examples of the resin less than 35 include polyolefins such as polyethylene and polypropylene, fluorine-based resins such as polytetrafluoroethylene, silicon resins, and rubbers. Addition of a different resin reduces the residual stress at the interface and enables good bonding. Examples of the reinforcing fiber include carbon fiber, glass fiber, metal fiber, ceramic fiber, and organic fiber. By adding the reinforcing fiber, the warping of the resin at the time of bonding is reduced, and good bonding can be obtained. Examples of the foaming agent include a physical foaming agent that uses hydrocarbons that are foamed by being vaporized from a liquid during heating, and a chemical foaming agent that utilizes reaction of a compound or thermal decomposition. Among them, a thermal decomposition type organic foaming agent such as an azo compound, a hydrazine derivative, a semicarbazide compound, an azide compound, a nitroso compound, or a triazole compound is preferable because the foaming start temperature is sharp. Moreover, since the water, residual solvent, monomer, and oligomer in the resin are foamed by heating, it can be used as a foaming agent. Examples of the colorant include carbon black, titanium oxide and other pigments and dyes. Examples of the filler include a reinforcing filler, a conductive filler, a magnetic filler, a flame retardant filler, and a heat conductive filler. Specifically, glass beads, glass flakes, silica, talc, kaolin, wollastonite, mica, alumina, hydrotalcite, montmorillonite, carbon nanotubes, carbon microtubes, fullerene, zinc oxide, zinc oxide, indium oxide, tin oxide , Iron oxide, titanium oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, red phosphorus, calcium carbonate, potassium titanate, lead zirconate titanate, barium titanate, aluminum nitride, boron nitride, zinc borate, boric acid Aluminum, barium sulfate, magnesium sulfate and the like can be mentioned. Preferably, these fillers are dispersed with a particle size of 1 μm or less. When the particle size is 1 μm or more, the laser transmittance is greatly reduced, and a large amount of energy is required for adhesion. Stabilizers include antioxidants such as hindered phenol antioxidants, sulfur antioxidants, phosphorus antioxidants, heat stabilizers, light stabilizers such as hindered amines, benzophenones, and imidazoles, metal stabilizers, and the like. An activator is mentioned. These additives may be used in combination of several types, not just one type.
Although it does not specifically limit as a form of the resin material of this invention, A film, a sheet | seat, an injection molded product, an extrusion molded product, a fiber, a nonwoven fabric, a film | membrane, a laminated body, and the form of a foam can also be used. Further, this patent also includes a molded product that is joined by a laser using a resin material processed in such a form.

As the adherend in the present invention, it is possible to use a different resin material, metal material, glass material, or ceramic material having a composition different from that of the resin material of the present invention.
Although the resin is not particularly limited as the different resin material used as the adherend in the present invention, it is preferable that the melting point or the glass transition point is equal or higher than that of the resin material of the present invention. When the melting point and glass transition point of the different resin material of the adherend are low, the different resin material that is the adherend is also softened by the laser, and it becomes difficult to maintain the form. Further, the surface free energy of the different resin material is preferably a resin close to the surface free energy of the resin material of the present invention from the viewpoint of compatibility of the resin. It is possible to use the same resin material as that of the present invention as the different resin material.
Examples of the metal material used in the present invention include iron, aluminum, titanium, copper, and alloys thereof, but are not particularly limited. However, metal materials having a low melting point such as magnesium, aluminum, and alloys thereof are not preferable because there is a possibility that sufficient heat cannot be input to the joint. In the present invention, a metal material made of carbon steel, stainless steel, titanium alloy or the like that can rapidly heat the joint to a high temperature is particularly preferable. The metal material is preferably subjected to a surface treatment for increasing the bonding force with the resin material. In the case of austenitic stainless steel SUS304, a high-strength joint is obtained with an unpolished receiving material, and the roughness of the surface of the metal material to be joined is determined as a result of experiments by the present inventors. It has been observed that there may be little impact on strength. The thickness of the metal material is not particularly limited, and may be a metal material having a thickness of 0.1 mm or more, further 1 mm or more, and further 3 mm or more.

  The glass materials used in the method of the present invention are as follows from the classification by chemical components. That is, “soda glass” made of silicic acid, soda ash and lime, “lead glass” made of silicic acid, calcium carbonate and lead oxide, “borosilicate glass” made of silicic acid, boric acid and soda ash, etc. However, it is not limited to these. The thickness of the glass material is not particularly limited, and may be a glass material having a thickness of 0.1 mm or more, further 1 mm or more, and further 3 mm or more.

  The ceramic material used in the present invention is as follows from the viewpoint of composition. That is, alumina and zirconia as oxides, silicon carbide as carbides, silicon nitride as nitrides, and other carbonates, phosphates, hydroxides, halides, and elements Although it is mentioned, it is not limited to these. The thickness of the ceramic material is not particularly limited, and may be a ceramic material of 0.1 mm or more, further 1 mm or more, and further 3 mm or more.

  The resin material of the present invention preferably generates bubbles by heating with a laser light source or ionizing radiation source. For example, it is possible to generate bubbles by generating gas by heating moisture in the hygroscopic resin material, generating gas by decomposing the resin material at a high temperature, or generating gas by a foaming agent.

  In the state in which the resin material of the present invention and the adherend (including different resin materials, metal materials, glass materials, ceramic materials, etc., as described above) are combined, Both materials can be firmly joined by heating with ionizing radiation or the like. The heating temperature of the bonded portion needs to be a temperature at which fine bubbles are generated inside the resin material. Specifically, it is equal to or higher than the softening temperature of the resin and lower than the softening temperature of the adherend. It is preferable that it is a C-1500 degreeC. The heating temperature is preferably not set to such a high temperature that the resin bubbles are accompanied by movement from the vicinity of the joint. This is because if the bubbles in the resin move, bonding due to pressure and heat associated with the generation of bubbles in the bonded portion cannot be expected. In addition, the upper limit of the sphere equivalent diameter of bubbles generated in the resin at the joint by heating is 5 mm or less, preferably 3 mm or less, more preferably 1 mm or less, and particularly preferably 0.5 mm or less from the viewpoint of bonding strength and appearance. is there. The lower limit is 0.0001 mm or more, preferably 0.001 mm or more, more preferably 0.01 mm or more, and particularly preferably 0.05 mm or more from the viewpoint of bonding strength.

As the laser light source, for example, a YAG laser, a fiber laser, a semiconductor laser, a carbon dioxide gas laser, or the like can be used. As the ionizing radiation source, for example, an electron beam, γ-ray, X-ray or the like can be used, and an electron beam is particularly preferable. Further, the irradiation of these heating sources may be either continuous irradiation or pulse irradiation.
When a laser light source is used, irradiation conditions such as laser power, power density, processing speed (moving speed), and defocus distance can be set as appropriate according to the purpose. For example, the power density of the laser is preferably 1 W / mm ^{2 to} 10 kW / mm ² . Moreover, it is preferable to set conditions for generating fine bubbles only in the resin material in the vicinity of the joint surface between the metal material, the glass material, or the ceramic material and the resin material. Specifically, when the power of the laser is increased, the joint becomes hot, and the subsequent cooling also slows down and the bubbles generated in the resin also increase. On the other hand, if the power is decreased, bubbles are not generated in the resin, or bubbles are generated. Is extremely reduced, and the bonding strength is reduced. The bonding strength increases when the molten resin is brought into close contact with the surface of a metal, glass or ceramic by rapidly generating bubbles of an appropriate size. In addition, when the laser defocusing distance is increased, the power density decreases, so it is possible to irradiate a large power laser that covers it, and as a result, good joints can be obtained over a wide range of conditions, and control is easy It is. In addition, when the moving speed of the laser is increased, the range of the laser power for obtaining a suitable bonding is widened, so that the control becomes easy. Note that the direction of the laser irradiation can form a strong joint even if it is performed from any material side in a state where the adherend and the resin material are combined.

  In a state where the resin material of the present invention and the adherend are combined, the thermally decomposed gas swells from the inside of the resin material by heating the joint between the resin material and the adherend with a laser, and the resin inside Bubbles are generated. The principle is not clear, but at this time, in the micro-size region, the explosive pressure accompanying the generation of bubbles is applied to the joint, and the resin material at the joint and the temperature of the adherend are high. Conditions that the adherend and resin material can be bonded to each other by physical bonding force such as anchor effect and / or chemical bonding force through metal, glass or ceramic oxide Meet and join. Further, when the resin material cools and hardens, the temperature of the bubbles also decreases, so that the pressure inside the bubbles is reduced and an adsorption force is also generated. It is possible to bond a strong metal, glass or ceramic and resin in a form in which these bonding forces are combined. Furthermore, by using laser light as a heating source, local rapid heating and rapid cooling are possible, and the pressure and adsorption force associated with the generation of bubbles can be increased. Bonding can be promoted.

  The method of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The measuring method is shown below about each physical property of the junction part of the resin material and to-be-adhered body measured in the Example.
1. Joint strength of joint (tensile shear strength and fracture state)
As a molded article for laser bonding, a film-like or plate-like resin material (each 70 mm long × 30 mm wide × thickness (see below)) and a plate-like adherend (each 70 mm long × 30 mm wide × thickness (each (See below))), and 20 mm out of 70 mm in length was left as a tensile test holding part, and 50 mm was overlapped and joined to obtain a tensile shear test piece. 10 mm each of the adherend and the resin material test holding part is sandwiched between the upper and lower chucks of a tensile tester (maximum load 1 ton) and pulled together at a speed of 5 mm / min to obtain a load-elongation curve, The breaking load was measured and used as the tensile shear strength. When the tensile shear adhesive strength was 50 kg or more, or the fracture (breakage) occurred in the base material of the resin material other than the joint (base material failure), the adhesive strength evaluation was evaluated as “good”. Moreover, adhesive evaluation was set to x in the case of what peeled spontaneously immediately after joining, or the adhesive force of less than 50 kg in a tensile shear test.
2. Bubbles in the bonded portion The bonded portion of the bonded body having the maximum bonding strength was observed with a stereomicroscope to confirm the presence or absence of bubbles.

[Example 1]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a metal resin bonding method according to the first embodiment. As shown in FIG. 1, a fiber laser beam 4 having a wavelength of 1090 nm is introduced from a fiber laser oscillator 1 into a laser processing head 3 by a fiber 2 and stopped by a condensing lens 5 having a focal length of 80 mm, in a direction away from the lens from the focal position. At a position 20 mm apart (beam diameter is 5 mm), the metal material stainless steel SUS 304 plate (thickness 2 mm) of the workpiece 6 and the resin material crystalline polyamide plate of the workpiece 7 (“T-714H manufactured by Toyobo Co., Ltd.) ”) (Thickness: 2 mm) was superposed, fixed by the clamp 8, and moved at a moving speed of 10 mm / s during irradiation with the laser beam 4. At that time, the crystalline polyamide of the workpiece 7 is located on the condenser lens 5 side (heating source side). When the workpiece 7 is irradiated with the laser beam 4, the laser beam 4 passes through the workpiece 7 as shown in FIG. 2, and the workpiece 6 has a high absorption rate with respect to the wavelength of the laser beam 4. Stainless steel is mainly heated, and due to heat transport 9 from the workpiece 6 to the workpiece 7, the boundary portion 10 between the workpiece 6 and the workpiece 7 and its peripheral portion have heat. As a result, as shown in FIG. 3, thermal decomposition occurs inside the crystalline polyamide of the workpiece 7 and gas is generated, whereby bubbles 11 are formed. At this time, the pressure 12 accompanying the generation of the bubbles 11 is generated, the temperature of the metal material of the workpiece 6 is lower than the melting point temperature, and the temperature of the resin material of the workpiece 7 is heated above the softening temperature. In combination, the resin material of the workpiece 7 and the metal material of the workpiece 6 can be physically bonded such as an anchor effect or chemically bonded through a metal oxide in the periphery of the bubble 11. Meet the conditions to be joined. Further, when the irradiation of the laser beam 4 is stopped, the bubbles 11 are rapidly cooled, the pressure 12 is lowered, and a force 13 for adsorbing the stainless steel of the workpiece 6 is generated as shown in FIG. These bonding forces were combined to form a metal resin bonding portion 14 as shown in FIG.

In Example 1, the graph showing the tensile shear load of a junction part when a laser power is changed at 0-1000W is shown in FIG. As is clear from FIG. 6, the tensile shear load at the joint is low at a low laser power with almost no bubbles, but when a moderately large bubble is generated as the laser power increases, an extremely high tensile shear load at the joint. was gotten. However, when the laser power was increased too much, the bubbles were enlarged and the tensile shear load was decreased. In addition, as shown in FIG. 6, in the tensile shear load measurement test, the joint where moderately large bubbles were generated showed fracture of the base material, but the joint or bubbles where bubble generation was insufficient was enlarged. The joints exhibited joint failure. Thus, it is clear that foaming is effective for improving the adhesive force.
Similarly, in Examples 2 to 10 and Comparative Examples 1 and 2, the laser power (0 to 1000 W) was changed, and the highest bonding strength and the presence or absence of bubbles at that time were observed. The thickness on the adherend side was unified at 2 mm.

  Examples are shown below, but are not limited thereto. Table 1 shows the resins used in Examples and Comparative Examples and their surface free energy, melting point, and glass transition temperature obtained from their shapes, thicknesses, and contact angles. Table 2 shows the resin or resin composition used, the type of adherend, the laser incident direction, the bonding strength, and the presence or absence of foaming at the bonded portion. As shown from the Examples, the adhesion with the adherend is good in the resin having a surface free energy of 35 mN / m. In particular, in Examples 1 to 4, 6, 8, and 10, foaming was observed. In Examples 5, 7, and 9, excellent adhesive strength was exhibited even under foaming conditions, but the strongest adhesive strength was exhibited in the unfoamed state due to the strength of the resin. On the other hand, some of the comparative examples foamed, but the surface free energy of the resin was less than 35 mN / m, and sufficient adhesive strength was not obtained.

By using the resin and the resin composition of the present invention, it is possible to perform strong laser bonding between a different resin material, a metal material, a glass material, or a ceramic material and the resin material. In addition, stronger laser bonding is possible by foaming with a laser. Furthermore, it is also characterized by using a molded article for laser bonding obtained from these laser welding resins or resin compositions. The molded article of the present invention can be provided as automotive interior / exterior parts, electrical parts, electronic material parts, building material parts, household goods, office supplies, medical parts, industrial material goods, clothing goods, etc. It can be industrially useful.

The figure which shows the structure of the metal resin joining method which concerns on the form of Example 1. FIG. Schematic of the joining process at the initial stage of laser irradiation in the metal resin joining method according to the form of Example 1 Schematic of the joining process at the time of void generation in the metal resin joining method according to the form of Example 1 Schematic of the bonding process immediately after laser irradiation in the metal resin bonding method according to the form of Example 1 The figure which shows the metal resin joining produced | generated with the metal resin joining method which concerns on the form of Example 1 The laser power (0 to 1000 W) according to the form of Example 1 is changed, and the highest bonding strength at that time and the presence or absence of bubbles at that time

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fiber laser oscillator 2 Fiber 3 Laser processing head 4 Fiber laser beam 5 Condensing lens 6 Work piece 7 Work piece 8 Clamp 9 Heat transport 10 Boundary part 11 of work pieces 6 and 7 Air gap 12 With generation of air gap 11 Pressure 13 Adsorbing force 14 Metal resin joint

Claims (7)

  Laser welding resin having a surface free energy of 35 mN / m or more.   The resin for laser welding according to claim 1, having a melting point of 150 ° C or higher.   The laser welding resin according to claim 1, wherein the glass transition temperature is 20 ° C or higher.   Any one of the main chain, side chain and / or terminal of the resin according to any one of claims 1 to 3, wherein imino group, amide group, ester group, urethane group, imide group, ether group, carbonate in the resin structure Any one of a binding component such as a group, a urea group, or an ionic group or a reactive group such as a carboxylic acid, a hydroxyl group, a metal sulfonate group, an amine group, a glycidyl group, a silanol group, a carbodiimide group, or an isocyanate group. Laser welding resin characterized by containing.     The resin according to any one of claims 1 to 4, wherein any one of a different resin, a reinforcing fiber, a foaming agent, a colorant, a filler, a foaming agent, a stabilizer strong fiber, a colorant, a filler, a foaming agent, and a stabilizer. A resin composition for lasers comprising one or more of these.     The resin and resin composition for laser welding according to any one of claims 1 to 5, wherein the resin is foamed by a laser.     A molded article for laser bonding obtained from the laser welding resin or resin composition according to claim 1.

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