JP4849574B2 - Joining method using laser light - Google Patents

Description

The present invention relates to a method of bonding a first member made of a material permeable to laser light, and a second member made of a first member of the same or different materials by laser welding. The present invention also relates to a joined product obtained by such a method .

  As a method for joining members made of different materials such as resins or materials other than resin and resin, a joining method by laser light irradiation (so-called laser welding method) has been used. This is because a transparent member that is transparent to laser light and a non-transmissive member that is not transparent to laser light are brought into contact with each other, and then the laser light is irradiated from the transparent member side and transmitted. This is a method in which the contact portion between the permeable member and the non-permeable member is heated and melted to integrally bond the two. In such a method, it is necessary to use a combination of laser transmissive and non-transmissive materials, or materials having low affinity to each other cannot be bonded satisfactorily. It was restricted. Moreover, even if it was able to join, the intensity | strength and reliability were not enough.

  When performing laser bonding, it is important to irradiate the laser while keeping the gap between the members to be bonded constant. That is, if the gap is too narrow, the local volume change of the resin melted by laser irradiation cannot be absorbed, and undesirable residual stress may occur. If the gap is too wide, the area to be melted and bonded is insufficient. There is a fear. Therefore, in order to keep the gap between the members in the range of several μm to several tens of μm, a method is adopted in which laser irradiation is performed while applying a certain pressure. However, it has been difficult to maintain a constant gap by applying an appropriate pressure to a member having a complicated shape.

  As a method for joining laser-transmitting materials by laser welding, a laser-absorbing member is laminated with a resin member containing a toner or paint that absorbs laser light at the bonding interface between the laser-transmitting members. A method of irradiating light has been proposed (see, for example, Patent Documents 1 to 3). The laser absorber interposed between the laser transmissive materials absorbs the energy of the laser beam, so that the bonding interface between the two melts and joins. Yes. However, when dissimilar materials are joined together by such a method, stress is likely to be generated at the joining interface due to the difference in the linear expansion coefficient, so that sufficient joining strength may not be obtained and peeling may occur easily. . Further, as described above, it was still difficult to perform laser irradiation while maintaining an appropriate gap.

  As a method of joining resin materials having low compatibility with each other, from a first resin member made of a first resin material having laser transparency, and a second resin material having low compatibility with the first resin member and no laser transparency. The first resin member and the second resin member are integrally formed by irradiating a laser beam with an alloy resin material made of the first resin material and the second resin material interposed between the first resin member and the second resin member. A joining method is disclosed (see Patent Document 4). Thereby, even if it is resin materials with little compatibility, it is supposed that it can join favorably. However, in this joining method, since it is necessary to use an alloy (polymer composition) composed of two kinds of resins to be joined, it can be used for joining resin materials, but for joining a resin and an inorganic substance such as a metal. Could not be used. In general, since the first resin material and the second resin material are both hard resins, the obtained alloy resin material is also a hard material, and it is difficult to closely adhere to the shape of the joint surface. . It is speculated that by interposing such an alloy resin material, the stress caused by the difference in linear expansion coefficient between the resins at the bonding interface and the residual stress at the time of bonding can be alleviated to some extent, but it is still insufficient. there were.

  A method of sandwiching a sheet made of an elastomer between a first member made of a laser transmissive material and a second member made of the same material as or different from the first member, and irradiating a laser beam from the first member side for joining Has been proposed (see Patent Documents 5 and 6). By interposing a flexible sheet in this way, it can be closely adhered to the shape of the joint surface, and stress caused by the difference in linear expansion coefficient between resins at the joint interface or residual stress at the time of joining Can be relaxed. However, depending on the type of resin used as the first member or the second member, good adhesive force may not be obtained, and improvement has been desired. In particular, when trying to join a resin having a high crystallinity and a high melting point, there are many cases where sufficient adhesive strength cannot be obtained.

JP 2003-181931 A JP 2004-1071 A JP 2005-238462 A JP 2002-18961 A JP 2008-7584 A WO2008 / 044349

The present invention has been made to solve the above-described problems, and provides a laser bonding method that can be used for bonding various materials and can obtain high bonding strength with a simple operation. With the goal. Moreover, it aims at providing the joined article obtained by such a joining method .

The above-described problem is a joining method for joining a first member made of a material having transparency to laser light and a second member made of the same or different material as the first member;
An intermediate for laser bonding comprising a polymer composition comprising a polymer (A) having a tensile modulus of elasticity at 23 ° C. of 0.01 to 500 MPa and a polymer (B) having a tensile modulus of elasticity of more than 500 MPa and not more than 10,000 MPa at 23 ° C. The member is sandwiched between the first member and the second member so as to contact the first member and the second member,
When the first member and the second member are joined by melting the laser joining sheet by irradiating laser light from the first member side,
The polymer (B) and the polymer constituting at least one of the first member and the second member include 50 mol% or more of structural units derived from the same monomer,
The weight ratio (A / B) of the polymer (A) to the polymer (B) is 40/60 to 95/5,
Solved by providing a joining method characterized in that particles of the polymer (B) are dispersed in a matrix of the polymer (A), and the thickness of the intermediate member for laser joining is 10 to 5000 μm. The

At this time, it is preferable that the intermediate member for laser bonding further contains a laser beam absorber. The polymer (A) is also preferably an elastomer modified with a monomer having a polar functional group. It is also preferred that the polymer (B) is a crystalline polymer having a melting point of 200 ° C. or higher and 400 ° C. or lower . It is also preferable that the intermediate member for laser bonding is formed by mixing the polymer (B) powder with the polymer (A).

At this time, the first member made of a polymer, Ri second member Do a metal, a polymer (B), the polymer constituting the first member, a constituent unit derived from the same monomer 50 mol % Or more is a preferred embodiment.

Furthermore, the above-described problem is sandwiched between a first member made of a material that is transparent to laser light, a second member made of the same or different material as the first member, and the first member and the second member. And a joined product having a laser joining intermediate member fused to each of the first member and the second member by laser irradiation;
The laser joining intermediate member includes a polymer (A) having a tensile elastic modulus at 23 ° C. of 0.01 to 500 MPa and a polymer (B) having a tensile elastic modulus at 23 ° C. of more than 500 MPa and 10000 MPa or less. Consisting of a combined composition,
The polymer (B) and the polymer constituting at least one of the first member and the second member include 50 mol% or more of structural units derived from the same monomer,
The weight ratio (A / B) of the polymer (A) to the polymer (B) is 40/60 to 95/5,
The problem can also be solved by providing a bonded product in which the particles of the polymer (B) are dispersed in the matrix of the polymer (A) and the thickness of the intermediate member for laser bonding is 10 to 5000 μm. Is done.

With the bonding method of the present invention, various materials can be laser-welded with high bonding strength by a simple operation.

It is a typical sectional view of the joined article obtained by the joining method of the present invention. It is a typical top view and sectional view for explaining a method of laminating the 1st member, the sheet for joining, and the 2nd member in an example. It is a schematic perspective view for demonstrating the measuring method of shear strength in an Example.

  The intermediate member for laser joining according to the present invention is for joining a first member made of a material having transparency to laser light and a second member made of the same material as or different from the first member by a laser welding method. Prior to the laser beam irradiation, the first member and the second member are sandwiched.

  The first member used in the present invention is made of a material that is transmissive to laser light (laser transmissive). Here, having transparency to the laser beam means that the laser beam as a heating source is transmitted with almost no reflection or absorption, or is not melted even if the laser beam is partially absorbed and / or reflected. It means having a transmittance that allows the remaining laser light to pass through and reach the intermediate member for bonding.

  Although it will not specifically limit if a 1st member consists of a material which has the above permeation | transmission with respect to a laser beam, For example, what consists of resin, glass, etc. is used suitably. Examples of resins include polyamides such as nylon 6 and nylon 66; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyolefins such as polyethylene and polypropylene; polyacetals; acrylic resins such as polymethyl methacrylate; polycarbonates; polyvinyl chloride; Styrenic resin such as; epoxy resin; fluoropolymer; polyphenylene sulfide; polyether ether ketone; polyphenylene ether; polysulfone; polyether sulfone; polyimide; The thing which has property is mentioned. As the glass, among various known materials such as soda lime glass, lead glass, and borosilicate glass, those having transparency to laser light can be widely used. Further, tempered glass, laminated glass, multilayer glass and the like can also be used.

  The second member used in the present invention may be made of the same material as that of the first member, or may be made of a material different from that of the first member. The laser transmissive material as described above or any other material can be used. As the laser transmitting material, the same material as that used for the first member can be used. Further, as the second member, in addition to the laser transmissive material, a material having a laser beam absorptivity (laser absorptivity) can be used.

  In the present invention, the expression “absorbing with respect to laser light” means that the laser light as a heat source is partially transmitted and / or reflected so that the remainder is absorbed and heated. Examples of such laser-absorbing materials include metals, ceramics, and inorganic filler-containing compositions obtained by adding inorganic fillers to polymers such as resins and rubbers. In addition, a material that is made laser-absorbing by adding a dye or a pigment to the laser-transmitting material can also be used. Furthermore, wood, paper, fabric, etc. can also be used.

  The metal may be a simple substance or an alloy of two or more metals. Further, as ceramics, various known types such as oxides such as zirconia and alumina (including composite oxides), carbides such as silicon carbide, nitrides such as silicon nitride, phosphates such as apatite, etc. Things can be used. Furthermore, the composite material of the said metal and ceramics etc. can also be used. Especially, it is preferable to use a metal as a 2nd member from a practical viewpoint, and steel, stainless steel, aluminum (alloy), copper (alloy), titanium (alloy), magnesium (alloy), etc. are illustrated.

  As the resin used in the inorganic filler-containing resin composition, each resin exemplified in the description of the laser transmitting material can be used. As the inorganic filler, a filler capable of absorbing laser light such as glass fiber, carbon fiber, silica, alumina, talc, carbon black, and inorganic powder coated with a material that absorbs laser is used. In many cases, a resin composition obtained by adding such an inorganic filler to a resin has laser absorptivity as a whole composition. However, depending on the type and amount of the inorganic filler to be blended, it may be used as a laser transmissive material in the present invention.

  In the present invention, at least one of the first member and the second member needs to be made of the same type of polymer as the polymer (B). Here, the polymer (B) is a polymer component contained in a polymer composition constituting an intermediate member for laser bonding described later. At this time, it is a particularly preferable embodiment that the first member is made of the same type of polymer as the polymer (B) and the second member is made of metal.

  The intermediate member for laser bonding according to the present invention is irradiated with laser light while being sandwiched between the first member and the second member, and is heated and melted by the energy, whereby the first member and the first member Used to join two members. The said intermediate member for laser joining consists of a polymer composition containing the polymer (A) whose tensile elasticity modulus in 23 degreeC is 0.01-500 Mpa, and the polymer (B) whose tensile elasticity modulus in 23 degreeC exceeds 500 Mpa. .

  When the polymer composition constituting the intermediate member for laser bonding of the present invention contains the polymer (A) having a tensile elastic modulus at 23 ° C. of 500 MPa or less, the entire intermediate member becomes flexible, and the shape of the bonding surface is obtained. It becomes easy to make good contact with each other. The tensile elastic modulus of the polymer (A) is more preferably 200 MPa or less, and even more preferably 100 MPa or less. When the tensile elastic modulus at 23 ° C. of the polymer (A) is less than 0.01 MPa, the handling of the intermediate member may be difficult and the adhesive strength may be lowered.

  The polymer (A) is not particularly limited as long as it has a tensile elastic modulus at 23 ° C. of 500 MPa or less. Polyolefins represented by various modified polyethylenes such as ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid (ester) copolymer, ethylene-maleic anhydride copolymer; Various resins such as an acrylic resin such as a (meth) acrylate copolymer; a polyester resin; a polyamide resin; a polystyrene resin; a polyvinyl chloride resin; and a polyurethane resin can be used.

  An elastomer is suitably used as the polymer (A). This is because it is flexible and elastic, and is suitable for being brought into close contact with the shape of the joint surface. As the elastomer, a thermoplastic elastomer or a crosslinked rubber can be used, and is not particularly limited. As the cross-linked rubber, various known ones such as isoprene-based rubber and butadiene-based rubber can be used. However, since a highly cross-linked rubber may lower the laser weldability, the degree of cross-linking is lower. preferable. Examples of the thermoplastic elastomer include styrene elastomers, olefin elastomers, acrylic elastomers, polyester elastomers, polyurethane elastomers, polyamide elastomers, silicon elastomers, and fluorine elastomers. In the present invention, a thermoplastic elastomer is preferably used from the viewpoints of melt adhesion and processability.

  The polymer (A) is preferably modified with a monomer having a polar functional group. Since these polar functional groups have a high affinity with metals and polar resins, an intermediate member for laser bonding comprising a polymer composition containing a polymer (A) modified with a monomer having the polar functional group is used. Thus, the bonding strength between the intermediate member and the metal or polar resin can be increased. In addition, the polymer (A) having the polar functional group may have higher absorbability with respect to the laser beam than the polymer having no polar functional group depending on the wavelength of the laser beam to be used. In some cases, it can be suitably used. The polar functional group preferably has a polar group such as a carboxyl group (including a carboxylic anhydride group), an epoxy group, an amino group, a hydroxyl group or an ester group. Of these, the polymer (A) having a carboxyl group (including a carboxylic anhydride group) is particularly preferably used.

  Furthermore, the polymer composition constituting the intermediate member for laser bonding of the present invention contains a polymer (B) having a tensile elastic modulus at 23 ° C. exceeding 500 MPa. The polymer (B) is composed of the first member and the first member. It is the same type of polymer as that constituting at least one of the two members. In general, the first member or the second member to be laser bonded is often a hard resin. However, if such a hard resin is used as it is as an intermediate member for laser bonding, the intermediate member becomes too hard. Therefore, by blending such a hard polymer (B) with the flexible polymer (A), the entire intermediate member becomes flexible, and it becomes easy to adhere closely to the shape of the joint surface. In general, a polymer material having a high elastic modulus is often difficult to be laser-bonded, and even if such a polymer is used, the advantage of using the intermediate member for laser bonding according to the present invention, which can be expected to improve the adhesion, is great. Therefore, the tensile elastic modulus at 23 ° C. of the polymer (B) is more preferably 1 GPa (1000 MPa) or more, and further preferably 2 GPa (2000 MPa) or more. In general, the tensile modulus of elasticity of the polymer (B) at 23 ° C. is 10 GPa (10000 MPa) or less.

  Here, it is important that the polymer (B) is the same type of polymer as that constituting at least one of the first member and the second member, whereby the first member or the second member and the laser bonding are used. The adhesive force between the intermediate member is improved. It is possible to obtain a high adhesive strength by blending the polymer (B) having affinity with the first member or the second member while making the entire intermediate member soft and closely adhering to the shape of the joining surface. it can.

  Here, the “same kind of polymer” means that the polymers belong to the same group for classification. For example, it refers to those belonging to groups such as polyolefin, polyester, polyamide, polyphenylene sulfide, polyoxymethylene, acrylic resin, polycarbonate, polyvinyl chloride, styrene resin, and epoxy resin. At this time, even if it is a composition containing the polymer of another group in the range which does not inhibit the effect of invention, it shall be the same group. Here, when the polymer is a copolymer, the polymers are grouped on the basis of the constituent component having the highest weight ratio. For example, since SEBS (styrene-hydrogenated butadiene-styrene block copolymer) used in Example 1 of the present application has a styrene content of 32% by weight, it contains hydrogenated butadiene units more than twice as much. . Here, since the hydrogenated butadiene unit is an ethylene-butylene unit, it is substantially an olefin unit. That is, since the content of olefin units is more than twice the content of styrene units, such copolymers are classified as polyolefins in the present invention.

  More preferably, the polymer (B) and the polymer constituting at least one of the first member and the second member contain 50 mol% or more of a structural unit derived from the same monomer, and contain 70 mol% or more. Further preferred. It is optimal that both are substantially the same polymer.

  The polymer (B) is not particularly limited as long as the tensile elastic modulus at 23 ° C. exceeds 500 MPa. It may be a crystalline polymer or an amorphous polymer. In general, a crystalline polymer tends to adhere less easily when melted than an amorphous polymer, so that even such a polymer can be expected to improve adhesion. The benefit of using an intermediate member is great. In general, those having a high melting point are close to the melting temperature and the thermal decomposition temperature, and tend to be hard to be joined by laser joining. Therefore, the present invention can be expected to improve adhesion even with such a polymer. The advantage of using the intermediate member for laser bonding is great. Therefore, it is preferable that the polymer (B) is a crystalline polymer having a melting point of 200 ° C. or higher.

  Examples of crystalline polymers having a melting point of 200 ° C. or higher include polyphenylene sulfide; polyether ether ketone; polyphenylene ether; polysulfone; polyether sulfone; polyacetal; polyimide; polyether imide, aliphatic polyamides such as PA6 and PA66, and polyhexamethylene. Semi-aromatic polyamides such as terephthalamide, polyhexamethylene terephthalamide / isophthalamide, polynanomethylene terephthalamide, and wholly aromatic polyamides such as poly p-phenylene terephthalamide and poly m-phenylene isophthalamide (aramid) ) Containing polyamides; semi-aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyesters including wholly aromatic polyesters (polyarylate); fluororesins, etc. It is exemplified. More preferably, the melting point of the polymer (B) is 250 ° C. or higher. Usually, the melting point of the polymer (B) is 400 ° C. or lower.

  The weight ratio (A / B) of the polymer (A) to the polymer (B) in the polymer composition constituting the intermediate member for laser bonding is not particularly limited, but is preferably 10/90 to 95/5. . When the weight ratio (A / B) is less than 10/90, the flexibility of the intermediate member may be reduced, and it may be difficult to closely adhere to the shape of the joint surface. The weight ratio (A / B) is more preferably 20/80 or more, and further preferably 40/60 or more. On the other hand, when the weight ratio (A / B) exceeds 95/5, the adhesive force between the first member or the second member made of the polymer (B) and the intermediate member for laser bonding becomes insufficient. There is a case. The weight ratio (A / B) is more preferably 90/10 or less, and even more preferably 80/20 or less. In particular, when importance is attached to the flexibility of the intermediate member, the content of the polymer (A) is made larger than the content of the polymer (B), that is, the weight ratio (A / B) exceeds 50/50. However, it is preferable.

  Further, in the polymer composition, the polymer (B) particles are preferably dispersed in the polymer (A) matrix. By having such a dispersed form, the flexibility of the intermediate member is improved, and it is easy to make the intermediate member adhere well along the shape of the joint surface. Even if the polymer (A) constitutes a matrix and the polymer (B) is contained in the form of particles, it is surprising that the adhesiveness is improved, thereby achieving both flexibility and adhesiveness. can do.

  For the purpose of improving the laser absorptivity of the intermediate member for laser bonding, it is also preferable that the intermediate member contains a laser beam absorber (hereinafter also referred to as “laser absorber”). The laser absorber in the present invention refers to a material that can improve the laser absorptivity of the intermediate member when added. Examples of such laser absorbers include inorganic pigments such as carbon black and composite oxide pigments; organic pigments such as phthalocyanine pigments, lake pigments, and polycyclic pigments; and various types of pigments depending on the wavelength of the laser light used. Known materials such as dyes can be used as appropriate. The blending amount of the laser absorber varies greatly depending on the type, but is usually about 0.01 to 20 parts by weight with respect to 100 parts by weight of the base polymer.

  In order to impart tackiness to the intermediate member for laser bonding, a tackifier may be added. Since the intermediate member has adhesiveness, when the intermediate member is sandwiched between the first member and the second member prior to the irradiation of the laser beam, the intermediate member can be temporarily fixed to the joining surface easily. Workability is greatly improved. Moreover, the improvement of the adhesive strength derived from adhesive force can also be expected. Examples of tackifiers include coumarone resins such as coumarone / indene resin and coumarone resin / naphthene oil / phenol resin mixtures; terpene resins, modified terpene resins (eg, aromatic modified terpene resins), terpene-phenol resins And terpene resins such as hydrogenated terpene resins; gum rosin, tall oil rosin, wood rosin, rosin pentaerythritol ester, rosin glycerol ester, hydrogenated rosin, hydrogenated wood rosin, hydrogenated rosin methyl ester, hydrogenated rosin Pentaerythritol ester, hydrogenated rosin triethylene glycol ester, disproportionated rosin, polymerized rosin, rosin derivatives such as polymerized rosin glycerol ester and cured rosin; terpine tackifier; aromatic hydrocarbon resin, Aliphatic hydrocarbon resins, unsaturated hydrocarbon (olefin, diolefin) polymers, isoprene resins, hydrogenated hydrocarbon resins, hydrocarbon tackifying resins, polybutene, liquid polybutadiene, low molecular weight butyl rubber, etc. Examples thereof include petroleum hydrocarbon resins; styrene resins; phenol resins; xylene resins. Among these, terpene resin is preferable. Moreover, other various additives can also be mix | blended.

  The thickness of the intermediate member for laser bonding is preferably 10 to 5000 μm. When the intermediate member has an appropriate thickness, when the first member and the second member are joined by heating and melting with the energy of the laser beam, it is possible to moderate the stress generated at the joining interface between the two members. It becomes. If the intermediate member is too thin, there is a risk that it will be insufficient to relieve the stress between the two members. From such a viewpoint, the thickness of the intermediate member is more preferably 20 μm or more, and further preferably 50 μm or more. On the other hand, when the intermediate member is thick, it may be necessary to devise the laser light irradiation conditions in order to melt and bond the joint surfaces of both the first member and the second member. In addition, since there are cost requirements and problems with the strength of the intermediate member itself, the intermediate member should not be too thick. The thickness of the intermediate member is more preferably 2000 μm or less, and still more preferably 1000 μm or less. Here, the thickness of the intermediate member refers to the distance between the surface in contact with the first member and the surface in contact with the second member.

  The intermediate member for laser bonding of the present invention may be composed of a single layer of a polymer composition containing the polymer (A) and the polymer (B), or a multilayer structure containing the polymer composition. It doesn't matter. In the case of a multi-layer structure, a layer made of a polymer composition is arranged on the surface layer so that it comes into contact with the first member or the second member made of the same type of polymer as the polymer (B), and then the laser. Irradiate light.

  The manufacturing method of such a laser joining intermediate member is not particularly limited. Using a kneader such as a kneader or an extruder, the polymer (A) and the polymer (B) can be mixed and melt-kneaded before forming the intermediate member. In melt kneading, both can be mixed by melt kneading at a temperature higher than at least one of the polymer (A) and the polymer (B). At this time, other additives such as a laser beam absorber may be kneaded simultaneously. In the case of molding after melt-kneading, it may be molded after being pelletized once or may be molded directly. A desired molded product can be obtained by extruding from a die or rolling with a calender.

  Alternatively, the laser joining intermediate member may be produced by dissolving or dispersing the polymer (A) and the polymer (B) in a solvent, applying the solution to a release paper, and drying. At this time, other additives such as a laser beam absorber may be kneaded simultaneously. In particular, when a tackifier is blended, melt molding is often difficult, and thus it is often preferable to manufacture by such a method.

  When manufacturing the intermediate member for laser bonding according to the present invention, it is preferable that the powder of the polymer (B) is mixed with the polymer (A) and molded. At this time, the form of the polymer (A) is not particularly limited, and may be a pellet, powder, other shapes, or a solution. As will be described later, when melt-kneading at a low temperature or when applying a dispersion, the particle diameter of the powder is preferably smaller than the thickness of the intermediate member.

  When the polymer (A) and the polymer (B) are mixed by melt-kneading, generally the melting point (or softening point) of the polymer (B) is more than the melting point (or softening point) of the polymer (A). Since it is often high, it is preferable to melt-knead the polymer (A) and the powder of the polymer (B). In this case, melt kneading can be performed at a temperature not lower than the melting point (or softening point) of the polymer (A) and lower than the melting point (or softening point) of the polymer (B). Further, even when melt kneading at a temperature equal to or higher than the melting point (or softening point) of the polymer (B), the time required to disperse both polymers can be shortened, so that a short melt kneading operation is sufficient. Therefore, by thermally kneading the polymer (A) and the polymer (B) powder, thermal decomposition of the polymer during melt kneading can be suppressed. In particular, this is an effective method when the melting point (or softening point) of the polymer (B) is high.

  In the case of producing an intermediate member for laser bonding by dissolving and dispersing the polymer (A) and the polymer (B) in a solvent and then drying, the polymer (B) is generally more resistant to the solvent. Since the solubility is often low, it is preferable to use a dispersion in which the polymer (B) powder is dispersed in the polymer (A) solution.

  The intermediate member for laser bonding described above is sandwiched between the first member and the second member, and the intermediate member is melted by irradiating laser light from the first member side, so that the first member and the second member are joined. Is done. Hereinafter, the joining method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a bonded product obtained by the bonding method of the present invention. 1 is formed by laminating a first member 2, a laser bonding sheet 3, and a second member 4 in this order. In the joining method of the present invention, the laser joining sheet 3 is sandwiched between the first member 2 and the second member 4 as shown in FIG.

  In the present invention, any known laser beam such as a gas laser, a solid-state laser, or a semiconductor laser can be used and is not particularly limited. According to the kind and thickness of the first member, the second member, and the intermediate member for laser bonding, the one having the optimum wavelength and output can be selected and used. The laser beam is not limited to one having a single wavelength, and may be a mixture of two or more wavelengths. In addition, when the joining range is wider than the laser beam irradiation diameter, the laser light source or the laminated product to be joined (a laminate of the first member and the second member sandwiching the intermediate member) is moved as necessary. Laser light irradiation may be performed.

  Since the first member is transmissive to the laser beam, at least part of the laser beam irradiated from the first member side passes through the first member and reaches the intermediate member for laser bonding. When the intermediate member is made of a material that absorbs laser light, the intermediate member is heated and melted by the energy of the laser light absorbed by the intermediate member itself. At this time, since at least one of the first member and the second member is made of resin, the heat of the intermediate member is also transferred to these resins and melted. When the irradiation of the laser beam is finished, the resin of the intermediate member and the first member and / or the second member is cooled and solidified again, whereby the intermediate member and the resin are welded. On the other hand, when at least one of the first member and the second member is made of a material other than resin (metal, glass, ceramics, etc.), the intermediate member for laser bonding heated and melted by irradiation with laser light is made of a material other than these resins. By fusing and cooling and solidifying again after the end of the laser beam irradiation, the intermediate member and the material other than the resin are welded. In this way, the first member and the intermediate member, and the intermediate member and the second member are welded to each other at the joining interface, whereby the first member and the second member are joined.

  Further, when the laser joining intermediate member is made of a laser transmissive material, at least a part of the laser light reaching the intermediate member passes through the intermediate member and reaches the second member. In order for the laser transmissive intermediate member to be heated and melted, the second member needs to be heated by the laser beam to generate heat, and thus the second member needs to be made of a laser absorbing material. The intermediate member is heated and melted by the heat generated when the second member is heated by the laser beam, and then cooled and solidified, whereby the first member and the second member are joined. Thus, the joined product of the present invention having the first member, the second member, and the intermediate member sandwiched between them and fused to each of the first member and the second member is obtained. .

  In the bonding method of the present invention, the intermediate member for laser bonding is melted by irradiation with laser light, and the first member and the second member are bonded. Therefore, as described above, the intermediate member and the joining interface on the intermediate member side of the first member and / or the second member are subjected to a thermal cycle in which they are heated by laser light irradiation and then cooled. At this time, stress due to the difference in linear expansion coefficient between the first member and the second member may occur at the bonding interface. However, when a flexible intermediate member is used, such stress can be relaxed. Further, it is possible to prevent the bonding strength from being lowered or peeled off. Thereby, the reliability of joining can be improved. In addition, thermal stress and mechanical stress are generated at the bonding interface due to the use of the obtained bonded product. Even in such a case, the stress and stress are alleviated when a flexible intermediate member for laser bonding is used. Therefore, the bonding strength can be maintained even after long-term use.

  Examples of the combination of the first member and the second member (first member / second member) include resin / resin, resin / metal, resin / ceramics, resin / glass, glass / resin, and the like. When only one of the first member and the second member is a resin, the resin is made of the same type of polymer as the polymer (B). Moreover, when both the 1st member and the 2nd member are resin, at least one should just consist of the same kind of polymer as a polymer (B). Among these combinations, when the first member is made of the same type of polymer as the polymer (B) and the second member is made of a metal, the combination effectively exhibits the effects of the present invention. Is also a particularly important combination. In this case, not only the first member and the second member can be firmly bonded, but also the stress generated due to the difference in thermal expansion coefficient can be reduced by the intermediate member of the present invention.

  Hereinafter, the present invention will be described more specifically with reference to examples. Test methods in the following examples are as follows.

(1) Tensile elastic modulus Based on JIS K7161 and JIS K6251, the tensile elastic modulus specified in “4.6 Tensile elastic modulus” of JIS K7161 was measured and calculated. The shape of the sample was “Dumbell No. 3 type”. The measurement was performed after adjusting the condition in an environment of 23 ° C.

(2) Shear strength A shear test of the obtained bonded product was performed by Instron 3382 (Instron Corporation). As shown in FIG. 3, a spacer 8 made of the same member as the first member 2 is overlapped on the joining surface side of the second member 4 and fixed with a chuck of the testing machine, and a spacer made of the same member as the second member 4. 9 was stacked on the joining surface side of the first member 2 and fixed to the chuck of the testing machine. Subsequently, a tensile test parallel to the first member 2 and the second member 4 (arrow direction in the figure) was applied, and a shear test was performed. At that time, the shear rate was 0.5 mm / sec and the maximum strength was obtained. The maximum strength (N) obtained was defined as the shear strength.

Example 1
A styrene-hydrogenated butadiene-styrene triblock copolymer modified with a monomer having a carboxyl group using a plastmill manufactured by Toyo Seiki Co., Ltd. (modified SEBS: styrene content 32% by weight, molecular weight 52,000: tensile) 67 parts by weight of pellets having an elastic modulus of 80 MPa) and 33 parts by weight of pellets of polyamide 6 (poly-ε-caprolactam (PA6): melting point 225 ° C .: tensile elastic modulus 2.7 GPa) were melt-kneaded at 230 ° C. to obtain a polymer. Composition pellets were obtained. To 100 parts by weight of the obtained polymer composition pellets, 0.5 part by weight of a near-infrared absorber (“IR-13F” manufactured by Showa Denko KK) is uniformly mixed, and then 190 ° C. using the plastmill. The mixture was melt kneaded to obtain near infrared absorbing polymer composition pellets. The obtained near-infrared absorbing polymer composition pellets were press-molded at 190 ° C. to obtain a sheet having a thickness of 100 μm. In the obtained sheet, the polyamide 6 particles were dispersed in the matrix of the modified SEBS.

  In this embodiment, a polyamide 6 plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the first member 2, and an aluminum alloy (A5052) having a width of 25 mm, a length of 50 mm, and a thickness of 1.5 mm is used as the second member 4. ) A board was used. As shown in FIG. 2, the first member 2 and the second member 4 are shifted by 25 mm in the length direction and overlapped so that the first member 2 is on top, and between the first member 2 and the second member 4 (FIG. 2). A laminated product was obtained by sandwiching the obtained bonding sheet (3 in the figure) between the overlapping portions indicated by A in FIG. Heating by laser irradiation was performed on the overlapped portion of the obtained laminate from above (first member side) under the following conditions. A pressure of 0.4 MPa was applied from both sides to the overlapped portion of the obtained laminated product, and heating by laser irradiation was performed from above (first member 2 side) under the following conditions. A 940 nm semiconductor laser was used as the laser. The collimated diameter of the laser beam is 46 mm, the focal length is 222.5 mm, the irradiation angle is 45 degrees, the minimum spot diameter is 1.52 mm, the focus is just focused on the surface of the first member, and the scanning speed is fixed at 750 mm / min. Then, as described in Table 1, the output was varied, and scanning was performed once at a length of 25 mm in the lateral direction. After completion of irradiation, the intermediate member for laser bonding was solidified again by air cooling, whereby the first member and the second member were bonded to obtain a bonded product. Table 1 shows the result of measuring the shear strength of the obtained bonded article.

Comparative Example 1
In Example 1, the laser joining intermediate member does not contain polyamide 6. Using a plastmill manufactured by Toyo Seiki Co., Ltd., a styrene-hydrogenated butadiene-styrene triblock copolymer modified with a monomer having a carboxyl group (modified SEBS: styrene content 32% by weight, molecular weight 52,000) A near-infrared absorbing polymer composition obtained by uniformly mixing 0.5 parts by weight of a near-infrared absorber (“IR-13F” manufactured by Showa Denko KK) with 100 parts by weight of a pellet and then melt-kneading at 190 ° C. Product pellets were obtained. The obtained near-infrared absorbing polymer composition pellets were press-molded at 190 ° C. to obtain a sheet having a thickness of 100 μm. Table 1 shows the results of measuring the shear strength of the obtained bonded product by heating by laser irradiation in the same manner as in Example 1 using the obtained bonding sheet.

  As shown in Table 1, in Comparative Example 1 in which the intermediate member for laser bonding did not contain polyamide 6, the shear strength reached a peak near the laser output of 200 W, and the maximum shear strength was about 1000 to 1100 N. The peeling surface at this time was an interface between the intermediate member and the polyamide 6. On the other hand, in Example 1 in which the intermediate member for laser bonding contains polyamide 6, the shear strength at a laser output of 300 W was about 1300 to 1350 N, and bonding was performed with a higher shear strength than in Comparative Example 1. Since the peeling surface at this time was an interface between the intermediate member and the aluminum alloy, it was found that the adhesive force at the interface between the intermediate member and the polyamide 6 was greatly improved. The reason why the shear strength of the bonded product of Example 1 is smaller than the shear strength of Comparative Example 1 when the laser output is small is that more heat energy is required because the high melting point polyamide melts than modified SEBS. It is believed that there is.

Example 2
Styrene-hydrogenated butadiene-styrene triblock copolymer modified with a monomer having a carboxyl group using a uniaxial Brabender (modified SEBS: styrene content 32 wt%, molecular weight 52,000: tensile modulus 80 MPa ) And 40 parts by weight of polyphenylene sulfide (PPS: melting point 280 ° C .: tensile elastic modulus 3.3 GPa) powder (particle size 100 to 200 μm) are melt-kneaded at 300 ° C. to form polymer composition pellets Got. Using 100 parts by weight of the obtained polymer composition pellets, 0.5 part by weight of a near-infrared absorber (“IR-13F” manufactured by Showa Denko KK) is uniformly mixed, and then using the uniaxial Brabender. The mixture was melt-kneaded at 200 ° C. to obtain a near-infrared absorbing polymer composition pellet. The obtained near-infrared absorbing polymer composition pellets were press-molded at 200 ° C. to obtain a sheet having a thickness of 100 μm. In the obtained sheet, polyphenylene sulfide particles were dispersed in a matrix of modified SEBS.

  In this embodiment, a polyphenylene sulfide plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the first member 2, and an aluminum alloy (A5052) having a width of 25 mm, a length of 50 mm, and a thickness of 1.5 mm is used as the second member 4. ) A board was used. As shown in FIG. 2, the first member 2 and the second member 4 are shifted by 25 mm in the length direction and overlapped so that the first member 2 is on top, and between the first member 2 and the second member 4 (FIG. 2). A laminated product was obtained by sandwiching the obtained bonding sheet (3 in the figure) between the overlapping portions indicated by A in FIG. Heating by laser irradiation was performed on the overlapped portion of the obtained laminate from above (first member side) under the following conditions. A pressure of 0.4 MPa was applied from both sides to the overlapped portion of the obtained laminated product, and heating by laser irradiation was performed from above (first member 2 side) under the following conditions. An 800 nm semiconductor laser was used as the laser. The collimated diameter of the laser beam is 46 mm, the focal length is 100 mm, and the minimum spot diameter is 600 μm. The irradiation angle was set to 0 degree (perpendicular incidence), and the laser was irradiated 10 mm closer to the surface of the first member from the position where it was just focused. The output was fixed at 200 W, the scanning speed was varied as described in Table 2, and scanning was performed once at a length of 25 mm in the short direction. After completion of irradiation, the intermediate member for laser bonding was solidified again by air cooling, whereby the first member and the second member were bonded to obtain a bonded product. Table 2 shows the result of measuring the shear strength of the obtained bonded product.

Comparative Example 2
In Example 2, the intermediate member for laser bonding does not contain polyphenylene sulfide. 100 weights of pellets of styrene-hydrogenated butadiene-styrene triblock copolymer (modified SEBS: styrene content 32% by weight, molecular weight 52,000) modified with a monomer having a carboxyl group using a uniaxial Brabender NIR absorber (IR-13F manufactured by Showa Denko Co., Ltd.) 0.5 part by weight is uniformly mixed with the part, and then melt-kneaded at 200 ° C. to obtain a near-infrared absorbing polymer composition pellet. Obtained. The obtained near-infrared absorbing polymer composition pellets were press-molded at 200 ° C. to obtain a sheet having a thickness of 100 μm. Table 2 shows the result of measuring the shear strength of the obtained bonded product by heating by laser irradiation using the obtained bonding sheet in the same manner as in Example 2.

Example 3
In Example 2, a polypropylene (PP) plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the first member 2, and a polyphenylene sulfide plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the second member 4. Except for the above, a laser beam was irradiated in the same manner as in Example 2 to obtain a bonded product. Table 2 shows the result of measuring the shear strength of the obtained bonded product.

Comparative Example 3
In Comparative Example 2, a polypropylene (PP) plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the first member 2, and a polyphenylene sulfide plate having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm is used as the second member 4. Except for the above, a laser beam was irradiated in the same manner as in Comparative Example 2 to obtain a bonded product. Table 2 shows the result of measuring the shear strength of the obtained bonded product.

  As shown in Table 2, when the polyphenylene sulfide plate and the aluminum alloy plate are joined (Example 2, Comparative Example 2), when the polyphenylene sulfide plate and the polypropylene plate are joined (Example 3, Comparative Example 3). In addition, the case where the intermediate member contained polyphenylene sulfide was bonded with higher shear strength than the case where the intermediate member did not contain polyphenylene sulfide. From this, it is understood that the adhesive strength at the interface between the intermediate member and the polyphenylene sulfide plate is improved by the polyphenylene sulfide blended in the intermediate member.

1 Joined Product 2 First Member 3 Laser Joining Sheet (Laser Joining Intermediate Member)
4 Second member 8, 9 Spacer A Overlapping portion L Laser beam

Claims (7)

A joining method of joining a first member made of a material having transparency to laser light and a second member made of the same or different material as the first member;
An intermediate for laser bonding comprising a polymer composition comprising a polymer (A) having a tensile modulus of elasticity at 23 ° C. of 0.01 to 500 MPa and a polymer (B) having a tensile modulus of elasticity of more than 500 MPa and not more than 10,000 MPa at 23 ° C. The member is sandwiched between the first member and the second member so as to contact the first member and the second member,
The laser bonding sheet is melted by irradiating laser light from the first member side,
When joining the first member and the second member,
The polymer (B) and the polymer constituting at least one of the first member and the second member include 50 mol% or more of structural units derived from the same monomer,
The weight ratio (A / B) of the polymer (A) to the polymer (B) is 40/60 to 95/5,
A bonding method, wherein particles of the polymer (B) are dispersed in a matrix of the polymer (A), and the thickness of the intermediate member for laser bonding is 10 to 5000 μm.   The joining method according to claim 1, wherein the laser joining intermediate member further contains a laser beam absorber.   The joining method according to claim 1 or 2, wherein the polymer (A) is an elastomer modified with a monomer having a polar functional group. The joining method according to claim 1, wherein the polymer (B) is a crystalline polymer having a melting point of 200 ° C. or higher and 400 ° C. or lower .   The joining method according to claim 1, wherein the laser joining intermediate member is formed by mixing a polymer (B) powder with a polymer (A).   The first member is made of a polymer, the second member is made of a metal, and the polymer (B) and the polymer constituting the first member contain 50 mol% or more of structural units derived from the same monomer. The joining method in any one of -5. A first member made of a material that is transparent to laser light, a second member made of the same or different material as the first member, and the first member and the first member sandwiched between the first member and the second member A joined product having a laser joining intermediate member fused to each of the two members by laser irradiation;
The laser joining intermediate member includes a polymer (A) having a tensile elastic modulus at 23 ° C. of 0.01 to 500 MPa and a polymer (B) having a tensile elastic modulus at 23 ° C. of more than 500 MPa and 10000 MPa or less. Consisting of a combined composition,
The polymer (B) and the polymer constituting at least one of the first member and the second member include 50 mol% or more of structural units derived from the same monomer,
The weight ratio (A / B) of the polymer (A) to the polymer (B) is 40/60 to 95/5,
A bonded article, wherein particles of the polymer (B) are dispersed in a matrix of the polymer (A), and the thickness of the intermediate member for laser bonding is 10 to 5000 μm.

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