JP2008007584A - Joining method for different kinds of members and joined article of different kinds of members - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method which can be used for joining various materials and can maintain high joining strength by relaxing stress generated between different kinds of materials. <P>SOLUTION: The joining method comprising joining a first member 2 composed of a material having transparency to a laser beam and a second member 4 composed of a material different from the first member 2 comprises the steps of inserting an adhesive sheet 3 between the first member 2 and the second member 4, wherein the adhesive sheet 3 is composed of an elastomer having a storage modulus at 20°C of 0.05-500 MPa and has a thickness of 20-1,000 μm and irradiating a laser beam L onto the first member 2 to melt the adhesive sheet 3 to join the first member 2 and the second member 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for joining a first member made of a material having transparency to laser light and a second member made of a material different from the first member. Especially this invention is used suitably for joining of 2 types of materials from which a linear expansion coefficient differs, and joining of materials with low mutual affinity.

  As a method of bonding members made of different materials such as different types of resins or materials other than resin and resin, a bonding method by laser light irradiation (so-called laser welding method) has been used for some time. This is because a transparent member that is transparent to laser light and a non-transparent 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-transmitting and non-transmitting materials, or it is not possible to bond materials having low affinity to each other well. It was restricted. Moreover, even if it was able to join, the intensity | strength and reliability were not enough.

  As a method for joining laser transmissive materials by laser welding, a laser-absorbing member is laminated with a resin member containing toner or paint that absorbs laser light at the joining interface between the laser transmissive members. A method of irradiating a beam 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. .

  In addition, as a method for bonding resins having low affinity to each other, a first resin member made of a first resin material having laser permeability, and a second resin material having low laser compatibility with the first resin member. A mixed powder of the first resin powder made of the first resin material and the second resin powder made of the second resin material between the second resin member made of A method of irradiating a laser beam with a mixed powder containing what it has is disclosed (for example, see Patent Document 4). In laser welding, it is said that a resin material having low compatibility with each other can be satisfactorily bonded to each other by interposing a mixed powder of laser absorbing properties at the bonding interface between the first resin member and the second resin member. Yes.

  However, since it is necessary to use a mixed powder of two types of resins to be bonded in the above bonding method, it is necessary to prepare a mixed powder corresponding to the combination of resins to be bonded. Moreover, although such a method can be used for joining resin materials, it has been difficult to use for joining a resin and an inorganic substance such as a metal. Furthermore, by interposing the mixed powder at the bonding interface between the resins, it is estimated that the stress caused by the difference in linear expansion between the resins at the bonding interface can be alleviated to some extent. Some combinations were insufficient.

JP 2003-181931 A JP 2004-1071 A JP 2005-238462 A JP 2006-26974 A

  The present invention has been made to solve the above problems, and provides a bonding method that can be used for bonding various materials and can maintain high bonding strength by relaxing stress generated between different materials. The purpose is to do.

  The present inventors have a specific storage elastic modulus in a joining method for joining a first member made of a material having transparency to laser light and a second member made of a material different from the first member. It has been found that by interposing an elastomer sheet at the joint interface between the two materials, the stress generated at the joint interface can be reduced in the joining of various materials, thereby maintaining a high joint strength. Completed the invention.

  That is, the present invention is a joining method for joining a first member made of a material that is transparent to laser light and a second member made of a material different from the first member, and has a storage elasticity at 20 ° C. An adhesive sheet made of an elastomer having a rate of 0.05 to 500 MPa and having a thickness of 20 to 1000 μm is sandwiched between the first member and the second member, and the laser beam is irradiated from the first member side for the bonding. The sheet is melted to join the first member and the second member.

  At this time, it is preferable that the first member is made of a resin and the second member is made of a metal, glass, ceramics, or an inorganic filler-containing resin composition. More preferably, the second member is made of metal. Further, it is also preferable that the first member is made of a resin that does not substantially contain an inorganic filler, and the second member is made of an inorganic filler-containing resin composition.

Moreover, in this invention, it is also preferable that a 1st member consists of glass and a 2nd member consists of a metal, ceramics, resin, or an inorganic filler containing resin composition. At this time, it is more preferable that the 2nd member consists of resin or an inorganic filler containing resin composition which does not contain an inorganic filler substantially. It is also preferable that the first member and the second member are made of a resin, and that the difference between the solubility parameters of both resins (calculated from the Fedors equation) is 1 (cal / cm ³ ) ^1/2 or more.

  In the present invention, the elastomer is preferably a thermoplastic elastomer. Moreover, it is preferable that the thermoplastic elastomer used in the present invention is an olefin elastomer, a styrene elastomer, or an acrylic elastomer. Furthermore, it is preferable that the thermoplastic elastomer has a carboxyl group, an epoxy group, an amino group, or an anhydrous carboxyl group.

  It is also preferred that the adhesive sheet used in the present invention contains a laser beam absorber.

  The present invention also includes a first member made of a material that is transparent to laser light, a second member made of a material different from the first member, and the first member and the second member. A dissimilar member bonded article having an adhesive sheet fused to each of the first member and the second member, wherein the adhesive sheet is an elastomer having a storage elastic modulus at 20 ° C. of 0.05 to 500 MPa. It is a dissimilar member joining product which consists of 20-1000 micrometers in thickness.

  ADVANTAGE OF THE INVENTION According to this invention, in joining of dissimilar materials, it can maintain the high joining strength by relieving the stress which arises between dissimilar materials, and provides the joining method which can be used for joining of various materials. it can.

  The joining method of the present invention is a method for joining a first member made of a material having transparency to laser light and a second member made of a material different from the first member, at 20 ° C. By sandwiching an adhesive sheet made of an elastomer having a storage elastic modulus of 0.05 to 500 MPa and a thickness of 20 to 1000 μm between the first member and the second member, the laser beam is irradiated from the first member side. The adhesive sheet is melted to join the first member and the second member.

  The first member used in the present invention is made of a material that is transparent to laser light (laser transparent). Here, having transparency to the laser beam means that the laser beam as a heating source is transmitted without being reflected or absorbed, 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 adhesive sheet.

  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 the resin include polyamide resins such as nylon 6 and nylon 66; polyolefin resins such as polyethylene and polypropylene; polyoxymethylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; acrylic resins such as polymethyl methacrylate; polycarbonate resins; Among various known materials including vinyl chloride; styrene-based resins such as polystyrene and ABS, epoxy resins, and the like, those having transparency to laser light may be 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 only needs to be made of a material different from that of the first member, and the above-described laser transmissive material or other materials can be used. As the laser transmissive material, any material that is different from the first member among the materials that can be used for the first member can be used. As the second member, in addition to the laser transmissive material, a material having a laser beam absorptivity (laser absorptivity) can also be used.

  In the present invention, having an absorptivity with respect to a laser beam means that the laser beam as a heat source absorbs the remainder even if it is partially transmitted and / or reflected and has the property of being heated. Examples of such a laser-absorbing material include metals, ceramics, and inorganic filler-containing resin compositions obtained by adding an inorganic filler to a resin. 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.

  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, a composite material of the above metal and ceramics can also be used.

  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. A resin composition containing such an inorganic filler in a resin has laser absorbability as a whole composition.

  The adhesive sheet used in the present invention is made of an elastomer having a storage elastic modulus at 20 ° C. of 0.05 to 500 MPa and a thickness of 20 to 1000 μm. The adhesive sheet is irradiated with laser light while being sandwiched between the first member and the second member, and is heated and melted by the energy to join the first member and the second member. Used to do. As long as the elastomer in this invention has the storage elastic modulus of the said range, arbitrary polymeric materials, such as crosslinked rubber and a thermoplastic elastomer, can be used and it does not specifically limit. As the crosslinked rubber, various known rubbers such as isoprene rubber and butadiene rubber can be used. Examples of the thermoplastic elastomer include olefin elastomers, acrylic elastomers, styrene elastomers, polyester elastomers, polyurethane elastomers, polyamide elastomers, silicon elastomers, and fluorine elastomers. In the present invention, a thermoplastic elastomer can be preferably used from the viewpoints of melt adhesion and processability. Of these, olefin elastomers, acrylic elastomers, and styrene elastomers are more preferably used.

  In addition, when bonding a resin and a metal, or when bonding a hydrophobic resin and a polar resin, each of the thermoplastic elastomers has a carboxyl group, an epoxy group, an amino group, a carboxylic anhydride group, a hydroxyl group, or an ester group. It is preferable to have a polar group such as Among these, a thermoplastic elastomer having a carboxyl group, an epoxy group, an amino group or a carboxylic anhydride group is more preferably used. Since these polar groups have high affinity with metals and polar resins, by using an adhesive sheet made of an elastomer modified with a monomer having the polar group, the adhesive sheet and the metal or polar resin It is considered that the bonding strength can be increased. In addition, the elastomer having the polar group may be more absorbable with respect to the laser beam than the thermoplastic elastomer having no polar group depending on the wavelength of the laser beam to be used. Can be used. Further, when the adhesive sheet contains an after-mentioned laser beam absorber, if the elastomer having the polar group is used, the dispersibility of the absorber in the elastomer can be increased, so that the laser beam absorption rate is improved. The effect is also confirmed.

  The elastomer used in the present invention has a storage elastic modulus at 20 ° C. of 0.05 to 500 MPa. By using such an elastic material, stress (strain) at the interface between the two members caused by the difference in linear expansion coefficient can be reduced when two different materials are joined. For this reason, high adhesive strength can be maintained. When the storage elastic modulus is too low, the shape of the adhesive sheet cannot be maintained due to the influence of viscosity in the operating temperature range. Therefore, the storage elastic modulus at 20 ° C. of the elastomer is preferably 1 MPa or more, more preferably 10 MPa or more. On the other hand, if the storage elastic modulus is too high, the stress generated at the joint interface between the two members cannot be sufficiently relaxed. Therefore, the storage elastic modulus at 20 ° C. of the elastomer is preferably 300 MPa or less, more preferably 200 MPa or less.

  The thickness of the adhesive sheet is 20 to 1000 μm. The adhesive sheet used in the present invention has an appropriate thickness, so that when the first member and the second member are joined by heating and melting with the energy of laser light, the stress generated at the joining interface between the two members is relieved. It becomes possible. If the adhesive sheet is too thin, it is difficult to relieve the stress between the two members, which is not preferable. Therefore, the thickness of the adhesive sheet is preferably 800 μm or less, more preferably 600 μm or less. On the other hand, when the adhesive sheet is too thick, the laser beam irradiated from the first member side may not reach the interface between the adhesive sheet and the second member, so it is difficult to obtain a good bonding state. Become. From such a viewpoint, the thickness of the adhesive sheet is preferably 50 μm or more, and more preferably 80 μm or more.

  For the purpose of improving the laser absorptivity of the adhesive sheet, it is also preferable that the adhesive sheet contains a laser light absorbent (hereinafter also referred to as “laser absorbent”). The laser absorbent in the present invention refers to an agent that can improve the laser absorbability of the adhesive sheet 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.

  Hereinafter, the joining method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating an example of a dissimilar member bonded product obtained by the bonding method of the present invention. 1 is formed by laminating a first member 2, an adhesive sheet 3, and a second member 4 in this order. In the joining method of the present invention, as shown in FIG. 1, the adhesive sheet 3 is sandwiched between the first member 2 and the second member 4, and the laser beam L is applied in this state so that the position of each member does not shift. Irradiate from the first member side.

  In the present invention, any known laser beam such as a gas laser, a solid laser, or a semiconductor laser can be used and is not particularly limited. According to the types and thicknesses of the first member, the second member, and the adhesive sheet, those having the optimum wavelength and output can be selected and used. Further, the laser beam is not limited to one having a single wavelength, and may be a mixture of two or more wavelengths.

  Further, when the bonding range is wider than the irradiation diameter of the laser beam, the laser light source or the laminated product to be joined (the first member and the second member laminated with the adhesive sheet sandwiched) is moved as necessary. Laser light irradiation may be performed.

  Since the first member is transmissive to the laser beam, at least a part of the laser beam irradiated from the first member side passes through the first member and reaches the adhesive sheet. When the adhesive sheet is made of a material that absorbs laser light, the adhesive sheet is heated and melted by the energy of the laser light absorbed by the adhesive sheet itself. At this time, when at least one of the first member and the second member is made of resin, the heat of the adhesive sheet is also transferred to these resins and melted. When the irradiation of the laser beam is finished, the adhesive sheet and the resin of the first member and / or the second member are cooled and solidified again, whereby the adhesive sheet 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 adhesive sheet heated and melted by laser light irradiation is fused to the material other than resin. And after completion | finish of irradiation of a laser beam, by cooling and solidifying again, materials other than an adhesive sheet and resin are welded. In this manner, the first member and the second member are welded to each other, and the first member and the second member are joined by welding the adhesive sheet and the second member at the joining interface.

  Further, when the adhesive sheet is made of a laser-transmitting material, at least a part of the laser light reaching the adhesive sheet passes through the adhesive sheet and reaches the second member. In order for the laser-permeable adhesive sheet to be heated and melted, the second member needs to be heated by the laser beam to generate heat, so the second member needs to be made of a laser-absorbing material. The adhesive sheet is heated and melted by the heat generated by heating the second member with the laser beam, and then cooled and solidified, whereby the first member and the second member are joined. In this way, the first member, the second member, and the dissimilar member joined product of the present invention having the adhesive sheet sandwiched between them and fused to each of the first member and the second member Is obtained.

  The bonding method of the present invention is to bond dissimilar materials by melting an adhesive sheet made of an elastomer by laser light irradiation. Accordingly, as described above, the bonding sheet and the bonding interface of the first member and the second member on the bonding sheet side are subjected to a thermal cycle in which they are heated by laser light irradiation and then cooled. At this time, although stress due to the difference in the linear expansion coefficient between the first member and the second member is generated at the bonding interface, the dissimilar member bonded product obtained by the bonding method of the present invention has a storage elastic modulus at 20 ° C. of 0.05. Since an adhesive sheet made of an elastomer having a viscosity of ˜500 MPa is provided at the bonding interface between the two members, such stress can be relaxed, and a decrease in bonding strength and peeling can be prevented. Thereby, the reliability of joining can be improved. Furthermore, if an adhesive sheet made of the elastomer having the polar group is used, the members made of materials having low affinity can be bonded well while relaxing the stress at the bonding interface.

  In addition, thermal stress and mechanical stress are generated at the bonding interface due to the use of the obtained joined product of different members. Even in such a case, the stress and the stress are caused by the presence of an adhesive sheet made of an elastomer having a specific storage elastic modulus. Since the stress is relieved, the bonding strength can be maintained even after long-term use.

  As described above, the method of the present invention is also suitably used for joining different kinds of materials having different linear expansion coefficients, which are difficult to join by the conventional laser welding method, and joining materials having low affinity. be able to. Below, the example of the combination of the material which can implement this invention suitably is shown.

<First Embodiment>
When the first member is made of resin and the second member is made of metal or ceramics In the present embodiment, a case where a laser-permeable resin and an inorganic laser-absorbing material (metal or ceramics) are joined will be described. In the present embodiment, since the second member is made of a laser-absorbing material, the second member is heated by laser light irradiation, and the adhesive sheet is heated and melted by the heat conduction. After the irradiation of the laser beam, the molten adhesive sheet is cooled and solidified, whereby the adhesive sheet and the first member, and the adhesive sheet and the second member are welded at the interface. Thereby, joining of the 1st member and the 2nd member is made.

  In this embodiment, since the adhesive sheet is heated and melted by the energy of the laser light absorbed by the second member, the adhesive sheet may be laser-absorbing or laser-transmitting. However, in order to heat and melt the adhesive sheet more efficiently when irradiated with laser light, it is preferable to make the adhesive sheet laser-absorbing, for example, by containing the laser absorbent. In addition, since the metal has a high affinity with the polar group, when the metal is used as the second member, the first member is a nonpolar resin when an adhesive sheet made of an elastomer having a polar group is used. Moreover, since both members can be favorably joined, it is preferable. The same applies to the case where some ceramics having high affinity with the polar group are used as the second member.

  Conventionally, since resin and metal or ceramics have low affinity and the linear expansion coefficient is also greatly different, joining by the laser welding method is difficult, and even if it can be joined, stress or Strain is likely to occur, and it has been difficult to obtain sufficient bonding strength. However, by using the joining method of the present invention, the stress at the joining interface between both members can be relaxed. Furthermore, when an adhesive sheet made of an elastomer having a polar group is used, it has a high affinity for both resin, metal and ceramics, so it maintains high bonding strength coupled with the stress relaxation effect described above. can do.

Second Embodiment
When 1st member consists of resin which does not contain an inorganic filler substantially, and 2nd member consists of resin composition containing an inorganic filler In this embodiment, laser-permeable resin which does not contain an inorganic filler substantially, and inorganic The case where a filler containing resin composition is joined is demonstrated. When the resin and the inorganic filler-containing resin composition are bonded by the conventional laser welding method (without using the adhesive sheet in the present invention), the inorganic filler-containing resin composition is burned by the absorption of the laser beam by the inorganic filler. Therefore, it has been difficult to use the inorganic filler-containing resin composition for laser welding. However, since a thermoplastic elastomer generally has a lower melting point or softening point than a resin, a bonding interface between a resin as a first member and an inorganic filler-containing resin composition as a second member as in the present invention. By sandwiching the above adhesive sheet, laser welding can be performed at a lower temperature than when the adhesive sheet is not used. When the adhesive sheet absorbs a certain amount of laser light, the energy of the laser light reaching the second member can be reduced to some extent by absorbing the laser light of the adhesive sheet. As a result, the second member is protected by the adhesive sheet. For this reason, both members can be joined satisfactorily without the inorganic filler-containing resin composition being burned.

  The inorganic filler-containing resin composition also has laser absorbability as a whole composition because the inorganic filler in the composition has laser absorbability. Therefore, as in the first embodiment, the adhesive sheet may be either laser-absorbing or laser-transmitting. However, when the adhesive sheet is laser-absorbing, the energy of the laser light incident on the inorganic filler-containing resin composition as the second member is reduced. The problem of burning can be solved more effectively. Therefore, also in this embodiment, it is preferable that the adhesive sheet is made to be laser-absorbing, for example, by containing a laser absorber.

<Third Embodiment>
When one of the first member and the second member is made of resin and the other is made of glass In the present embodiment, a case where a resin and glass are bonded will be described. When both the resin and the glass have laser transparency, it is necessary that the adhesive sheet sandwiched between the two members has the ability to absorb laser light. Therefore, it is necessary to make the adhesive sheet laser-absorbing, for example, by incorporating a laser absorbent into the adhesive sheet. The bonding sheet is sandwiched between resin and glass and irradiated with laser light to bond them together. At this time, resin may be irradiated from the resin side with the resin as the first member and glass as the second member, or laser light may be irradiated from the glass side with the glass as the first member and resin as the second member. Good.

  In addition, when one of resin or glass has laser transparency and the other has laser absorption, both members can be obtained by irradiating laser light from this side, with the laser transparency as the first member. Bonding is performed. In this case, as in the first embodiment, the adhesive sheet may be either a laser-absorbing sheet or a laser-transmitting sheet, but the bonding sheet is more efficient when irradiated with laser light. In order to heat and melt the adhesive sheet, the adhesive sheet is preferably made of a laser-absorbing material.

  In addition, since glass has a high affinity with a polar group in the same manner as a metal, in this embodiment, when an adhesive sheet made of an elastomer having a polar group is used, a nonpolar resin is used as the first member or the second member. Is also preferable because both members can be bonded satisfactorily.

  As in this embodiment, even in materials having different linear expansion coefficients such as resin and glass, the elastomer of the adhesive sheet absorbs the stress caused by the difference between the two linear expansion coefficients, so that high bonding strength is maintained. be able to. In addition, when joining laser transmissive dissimilar materials, if an adhesive sheet having laser absorptivity is used, the adhesive sheet is heated and melted by laser irradiation, so that both members can be suitably bonded. is there.

<Fourth embodiment>
When the first member is made of glass and the second member is made of a metal, ceramic, or inorganic filler-containing resin composition In this embodiment, a laser-transmitting glass and a laser-absorbing material (metal, ceramic, or inorganic filler-containing resin) The case of joining the composition) will be described. In the present embodiment, as in the first and second embodiments, since the second member is made of a laser-absorbing material, the second member is heated by laser light irradiation, and the adhesive sheet is heated and melted by the heat conduction. To do. After the irradiation of the laser beam, the molten adhesive sheet is cooled and solidified, whereby the adhesive sheet and the first member, and the adhesive sheet and the second member are welded at the interface. Thereby, joining of the 1st member and the 2nd member is made.

  In this embodiment, since the adhesive sheet is heated and melted by the energy of the laser light absorbed by the second member, the adhesive sheet may be laser-absorbing or laser-transmitting. However, in order to heat and melt the adhesive sheet more efficiently when irradiated with laser light, it is preferable to make the adhesive sheet laser-absorbing by adding a laser absorbent or the like. For the same reason as described in the first and second embodiments, it is also preferable to use an adhesive sheet made of an elastomer having a polar group.

  Thus, according to the joining method of the present invention, it is possible to perform laser welding using not only resin but also glass as a member on the side irradiated with laser light. In addition, as in the other embodiments, the bonding sheet elastomer sandwiched between the glass and the metal or ceramic or inorganic filler resin composition relieves stress at the bonding interface, thus maintaining high bonding strength. can do.

<Fifth Embodiment>
A combination in which the first member and the second member are made of a resin, and the difference between the solubility parameters of both resins (calculated from the equation of Fedors) is 1 (cal / cm ³ ) ^1/2 or more. A case will be described in which resins having a difference in solubility parameter calculated from the equation of 1 (cal / cm ³ ) ^1/2 or more are joined. Conventionally, it has been difficult to join a hydrophobic resin and a polar resin having low affinity to each other using a laser welding method. However, by using an adhesive sheet made of the elastomer as in the present invention, even resins having low affinity such that the difference in solubility parameter is 1 (cal / cm ³ ) ^1/2 or more can be easily obtained. Bonding can be performed and high bonding strength can be maintained. In order to further exert the effect of the present invention that allows such low affinity resins to be satisfactorily joined together, the difference in solubility parameter is more preferably 2 or more, and even more preferably 3 or more. .

In the present invention, the solubility parameter refers to a value calculated from the Fedors equation and is determined by the method described in “Polymer Engineering and Science, Vol. 14, No. 2, p 147 to 154 (1974)”. As a combination of resins having a difference in solubility parameter of 1 (cal / cm ³ ) ^1/2 or more, polyolefin resin and polyoxymethylene, polyolefin resin and polyvinyl chloride, polyolefin and epoxy resin, polyolefin resin and polyamide resin, Examples thereof include, but are not limited to, acrylic resin and polyamide resin, and styrene resin and polyamide resin. Moreover, this embodiment can be used suitably also for joining of hydrophobic resin and polar resin.

  In this embodiment, when the resin used as the second member is a laser-absorbing material and the adhesive sheet can be heated and melted by the energy of the laser light absorbed by the second member, the adhesive sheet is a laser-absorbing material. Or may be laser transmissive. However, when the resin used as the second member is also a laser-transmitting material like the first member, the adhesive sheet sandwiched between the two members needs to be absorbable with respect to the laser beam. Therefore, it is necessary to make the adhesive sheet laser-absorbing by, for example, containing the laser absorbent as described above in the adhesive sheet.

  Moreover, since this embodiment joins resin with low affinity, it is preferable to use what consists of an elastomer which has a polar group as an adhesive sheet. Since the elastomer having a polar group has a high affinity for both the hydrophobic resin and the polar resin, when the laser beam is irradiated between the resins having low affinity as described above, the hydrophobic resin and Since the elastomer, the polar resin, and the elastomer are respectively welded, the hydrophobic resin and the polar resin can be joined well. In addition, since the adhesive sheet made of the elastic elastomer is interposed at the joint interface between the two members after joining, the stress caused by the difference in the linear expansion coefficient between the two members can be reduced, and the joint strength can be reduced. Can be maintained.

The following members were used as members to be joined used in the examples and comparative examples.
(1) Polypropylene (PP)
A plate made of polypropylene (PP; product name: PP-N-BN, manufactured by Shin-Kobe Electric Co., Ltd.) having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm was used. The solubility parameter of PP is 8.0 (cal / cm ³ ) ^1/2 .
(2) Polyoxymethylene (POM)
A plate made of polyoxymethylene (POM) resin (product name: polypen core acetal copolymer, manufactured by Nippon Polypenco Co., Ltd.) having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm was used. The solubility parameter of this POM is assumed to be 9.6 to 10.0 (cal / cm ³ ) ^1/2 .
(3) Glass fiber reinforced nylon A plate made of glass fiber reinforced nylon having a width of 25 mm, a length of 50 mm, and a thickness of 2 mm was used. The solubility parameter of this glass fiber reinforced nylon is assumed to be 12.7 to 13.6 (cal / cm ³ ) ^1/2 .
(4) Aluminum An aluminum plate having a width of 25 mm, a length of 50 mm, and a thickness of 1.5 mm was used.
(5) High-tensile steel A high-tensile steel plate (HT80) having a width of 25 mm, a length of 50 mm, and a thickness of 1.5 mm was used.
(6) Glass A slide glass having a width of 25 mm, a length of 50 mm, and a thickness of 1 mm was used.

<Production Example 1 of Adhesive Sheet>
Styrene-hydrogenated butadiene-styrene block copolymer (SEBS) (styrene content 32% by weight, molecular weight 50,000) is melt-molded into a sheet having a thickness of 500 μm and cut into a size of 25 mm in width and 20 mm in length. Thus, an adhesive sheet A was obtained. The storage elastic modulus of the adhesive sheet was determined by the following method. The viscoelastic spectrometer DMS6100 (SII Nanotechnology Co., Ltd.) was used to measure the dynamic viscoelasticity of the adhesive sheet, and the measured value at 20 ° C. and 10 Hz was defined as the storage elastic modulus in the present invention. The storage elastic modulus of the adhesive sheet A at 20 ° C. was 89 MPa. In addition, the storage elastic modulus of the adhesive sheet obtained in the following Production Examples 2 to 7 was determined by the same method.

<Production Example 2 of Adhesive Sheet>
After mixing 0.05% by weight of an infrared absorber (IR-13F; Showa Denko KK) with the SEBS used in Production Example 1 of the adhesive sheet, this was melt-molded into a sheet having a thickness of 500 μm. The adhesive sheet B was obtained by cutting into a size of 25 mm in width and 20 mm in length. The storage elastic modulus of the adhesive sheet B at 20 ° C. was 89 MPa.

<Production Example 3 of Adhesive Sheet>
After mixing 0.05% by weight of an infrared absorber (IR-13F; Showa Denko KK) with the SEBS used in Production Example 1 of the adhesive sheet, this was melt-molded into a sheet having a thickness of 100 μm. The adhesive sheet C was obtained by cutting into a size of 25 mm in width and 20 mm in length. The storage elastic modulus of the adhesive sheet C at 20 ° C. was 89 MPa.

<Production Example 4 of Adhesive Sheet>
SEBS modified with a monomer having a carboxyl group (styrene content 32% by weight, molecular weight 52,000) was melt-molded into a sheet having a thickness of 500 μm and cut into a size of 25 mm in width and 20 mm in length. An adhesive sheet D was obtained. The storage elastic modulus of the adhesive sheet D at 20 ° C. was 150 MPa.

<Manufacture example 5 of an adhesive sheet>
Adhesive sheet E was obtained using the same method as in Adhesive Sheet Production Example 4 except that the thickness of the adhesive sheet was 100 μm. The storage elastic modulus of the adhesive sheet E at 20 ° C. was 150 MPa.

<Manufacture example 6 of an adhesive sheet>
Infrared absorber (IR-13F; Showa Denko KK) was mixed with 0.05% by weight of the carboxy-modified SEBS used in Production Example 4 of the adhesive sheet, and this was formed into a sheet having a thickness of 100 μm. After molding, the sheet F for bonding was obtained by cutting into a size of 25 mm in width and 20 mm in length. The storage elastic modulus of the adhesive sheet F at 20 ° C. was 150 MPa.

<Manufacture example 7 of an adhesive sheet>
Infrared absorber (IR-T; Showa Denko KK) was mixed with 0.05% by weight of the carboxy-modified SEBS used in Production Example 4 of the adhesive sheet, and this was formed into a sheet having a thickness of 500 μm. After molding, the sheet G for bonding was obtained by cutting into a size of 25 mm in width and 20 mm in length. The storage elastic modulus of the adhesive sheet G at 20 ° C. was 150 MPa.

<Manufacture example 8 of an adhesive sheet>
Infrared absorber (IR-13F; Showa Denko KK) was mixed with 0.05% by weight of the carboxy-modified SEBS used in Production Example 4 of the adhesive sheet, and this was formed into a sheet having a thickness of 500 μm. After molding, the sheet H for bonding was obtained by cutting into a size of 25 mm in width and 20 mm in length. The storage elastic modulus of the adhesive sheet H at 20 ° C. was 150 MPa.

<Example 1>
A polypropylene plate was used as the first member, and an aluminum plate was used as the second member. As shown in FIG. 2, the first member 2 and the second member 4 are shifted by 30 mm in the length direction and overlapped so that the first member 2 faces upward, and between the first member 2 and the second member 4 (FIG. 2). A laminated product was obtained by sandwiching the adhesive sheet B (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. As a laser heat source, a three-wavelength mixed semiconductor laser of 800, 940, and 980 nm was used. The collimated diameter of the laser beam was 46 mm, the focal length was 100 mm, and the minimum spot diameter was 600 μm. Laser light irradiation was performed under conditions of an output of 250 W and an irradiation distance of 105 mm, and scanning was performed at a speed of 1 mm / sec for 15 mm with respect to the longitudinal direction of the first member (lateral direction in FIG. 2). The adhesive sheet B was melted by repeating the scanning of the laser light three times with a shift of 5 mm in the short direction (vertical direction in FIG. 2) of the first member. After the irradiation was completed, the adhesive sheet B was solidified again by air cooling, whereby the first member and the second member were joined through the adhesive sheet B to obtain a dissimilar member joined product.

  The shear test of the obtained dissimilar member joined product was performed by Instron 3382 (Instron Corporation). As shown in FIG. 3, a member 5 similar to the first member 2 is joined with a nut on the same surface as the joining surface of the second member 4, and is parallel to the first member 2 and the member 5 (in the direction of the arrow in the figure). ) Tensile force was applied and a shear test was performed. At that time, the shear rate was 10 mm / sec and the maximum strength was obtained. The obtained maximum strength was defined as shear strength. The test results are shown in Table 1. Further, when the fracture surface of the bonded product after the shear test was visually observed, each member or adhesive sheet was not burned or discolored by laser irradiation, and there was no problem in appearance.

<Examples 2 to 11>
Except for changing the output of the first member, the second member, the adhesive sheet, and the laser light as shown in Table 1, the first member is used via the adhesive sheet by using the same method as in Example 1. And a second member joined together to obtain a dissimilar member joined product. A shear test similar to that of Example 1 was performed on the obtained bonded product of different members. The results are shown in Table 1. Further, the fracture surface of the joined product after the shear test was visually observed.

  In any of the above Examples 1 to 11 in which resin was used as the first member and metal was used as the second member, it was possible to obtain a dissimilar member bonded product having a good bonded state. Further, as is apparent from the results in Table 1, in the case of bonding a resin and a metal, it is more suitable for bonding made of carboxy-modified SEBS than when using an adhesive sheet B or sheet C made of unmodified SEBS. It was found that the shear strength of the obtained bonded product was higher when the sheet F was used. This is presumably because a carboxy group having high affinity with the metal exists in the elastomer.

  Moreover, when Example 7 and Example 8 were compared, compared with Example 7 with a laser output of 170 W, Example 8 with a laser output of 200 W was able to obtain higher shear strength. . On the other hand, when the fracture surface of the bonded product of different members after the shear test was observed, some foaming was observed in the first member (POM resin), but it was usable. As described above, the optimum laser irradiation condition can be selected in consideration of the balance between the bonding strength of the obtained heterogeneous bonded product and the degree of damage to the first or second member due to the laser irradiation.

<Examples 12 to 15>
Except for changing the output of the first member, the second member, the adhesive sheet, and the laser light as shown in Table 2, the first member is used via the adhesive sheet by using the same method as in Example 1. And a second member joined together to obtain a dissimilar member joined product. The obtained bonded product was subjected to the same shear test as in Example 1. The results are shown in Table 2. When the fracture surface of the bonded product after the shear test was observed, no problem in appearance was observed as in Example 1.

As is apparent from Table 2, even resins having low affinity such that the difference in solubility parameter is 1 (cal / cm ³ ) ^1/2 or more can be easily joined using the joining method of the present invention. And high bonding strength could be obtained. Further, Example 14 using the adhesive sheet G made of carboxy-modified SEBS and containing an infrared absorber has a higher shear strength than Example 13 using the adhesive sheet A made of only unmodified SEBS. I was able to get it. This is presumably because polar groups having affinity for POM are present in the elastomer and the laser absorption rate of the adhesive sheet is improved by the infrared absorber.

<Examples 16 and 17>
By using the same method as in Example 1 except that the first member, the second member, the adhesive sheet, and the output of the laser beam are changed as shown in Table 3, the first member is interposed via the adhesive sheet. And a second member joined together to obtain a dissimilar member joined product. When the joining state was confirmed by visual and hand pulling, both had a good joining state. Thus, it was confirmed that by using the joining method of the present invention, both members can be satisfactorily joined regardless of whether the laser beam is irradiated from either the glass or the resin side.

<Examples 18 to 20>
Except for changing the output of the first member, the second member, the adhesive sheet, and the laser light as shown in Table 4, the first member is used via the adhesive sheet by using the same method as in Example 1. And a second member joined together to obtain a dissimilar member joined product. The cross section of each obtained dissimilar member joined product was observed with a stereomicroscope. Stereomicrographs of cross sections of the dissimilar member joined articles obtained in Examples 18 and 20 are shown in FIGS. 4 and 5, respectively.

  As shown in FIG. 4, in Example 18 where the laser output is 160 W, the adhesive sheet and the first member (PP) are melted only in a considerably narrower range than the irradiation diameter of the laser beam, and at the same time, Bubbles are generated. On the other hand, in Example 19 where the laser output was higher than that in Example 18, the generation of bubbles was confirmed in the melted part, but the adhesive sheet and the first member (PP) were melted in a slightly wider width than in Example 18. It was. From this, it was found that by increasing the laser irradiation energy, the melting of the adhesive sheet was promoted, and this heat of fusion was also transmitted to the PP of the first member. In the above-described Examples 7 and 8, considering that the higher laser output has higher shear strength, the region where the adhesive sheet and each member are welded is increased by increasing the laser output, This is considered to provide a high shear strength.

  Moreover, in Example 20 (FIG. 5) using the adhesive sheet H containing an infrared absorber, compared with Examples 18 and 19 using the adhesive sheet D not containing an infrared absorber, the adhesive sheet It was also observed that the melted width increased significantly and roughly corresponded to the laser beam irradiation diameter. In addition, generation of bubbles was not confirmed in the melted portion, and a good joint surface could be obtained. From these results, it is estimated that it is difficult to uniformly bond the first member and the second member through the bonding sheet only by heat conduction by absorption of laser light on the metal (high-tensile steel) surface. The And, by incorporating an infrared absorber in the adhesive sheet, the elastomer in the adhesive sheet efficiently absorbs the laser beam and melts uniformly, so that a more uniform joining state can be obtained. .

<Comparative Examples 1-7>
The first member, the second member, and the laser beam output were changed as shown in Table 5, and the laser beam was emitted from the first member side in the same manner as in Example 1 except that the adhesive sheet was not used. Irradiation was performed. However, in any example, the first member and the second member could not be joined.

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 the method of laminating the 1st member, the sheet for adhesion, and the 2nd member in an example. It is a schematic perspective view for demonstrating the measuring method of shear strength in an Example. 18 is a SEM image of a cross section of a dissimilar member bonded product obtained in Example 18. It is a SEM image of a section of a dissimilar member joined product obtained in Example 20.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joining goods 2 1st member 3 Adhesive sheet 4 2nd member 5 Shear test member A Overlapping part L Laser beam

Claims (12)

  A joining method of joining a first member made of a material having transparency to laser light and a second member made of a material different from the first member, and having a storage elastic modulus at 20 ° C. of 0.05 to An adhesive sheet made of an elastomer of 500 MPa and having a thickness of 20 to 1000 μm is sandwiched between the first member and the second member, and the adhesive sheet is melted by irradiating laser light from the first member side, A joining method comprising joining the first member and the second member.   The joining method according to claim 1, wherein the first member is made of a resin, and the second member is made of a metal, glass, ceramics, or an inorganic filler-containing resin composition.   The joining method according to claim 2, wherein the second member is made of metal.   The joining method according to claim 1, wherein the first member is made of a resin substantially containing no inorganic filler, and the second member is made of an inorganic filler-containing resin composition.   The joining method according to claim 1, wherein the first member is made of glass, and the second member is made of a metal, ceramics, a resin substantially free of an inorganic filler, or an inorganic filler-containing resin composition.   The joining method according to claim 5, wherein the second member is made of a resin substantially containing no inorganic filler or an inorganic filler-containing resin composition. The joining method according to claim 1, wherein the first member and the second member are made of a resin, and a difference in solubility parameter (calculated from the Fedors equation) between the two resins is 1 (cal / cm ³ ) ^1/2 or more.   The joining method according to claim 1, wherein the elastomer is a thermoplastic elastomer.   The joining method according to claim 8, wherein the thermoplastic elastomer is an olefin elastomer, a styrene elastomer, or an acrylic elastomer.   The joining method according to claim 8 or 9, wherein the thermoplastic elastomer has a carboxyl group, an epoxy group, an amino group, or an anhydrous carboxyl group.   The bonding method according to claim 1, wherein the adhesive sheet contains a laser beam absorber.   A first member made of a material that is transparent to laser light; a second member made of a material different from the first member; and the first member and the second member sandwiched between the first member and the second member A bonded member of different types having an adhesive sheet fused to each of the members, wherein the adhesive sheet is made of an elastomer having a storage elastic modulus at 20 ° C. of 0.05 to 500 MPa, and has a thickness of A dissimilar member joined product characterized by being 20 to 1000 μm.