JP7593074B2 - Manufacturing method of the joint body - Google Patents

Description

The present invention relates to a method for manufacturing a joined body formed by joining the same type of resin and different types of resin by ultrasonic welding, and a method for manufacturing a joined body formed by joining a resin and at least one material selected from metal, glass, and ceramics by ultrasonic welding. It also relates to a joined body formed by joining resins together by ultrasonic welding, and a joined body formed by joining a resin and at least one material selected from metal, glass, and ceramics by ultrasonic welding.

In recent years, from the viewpoint of reducing the weight and cost of products, it has become common to resinify parts in various fields, such as automobile parts, medical equipment, and home appliances, to produce resin molded products. Also, from the viewpoint of improving the productivity of resin molded products, a method is sometimes used in which a resin molded product is molded by dividing it into multiple parts in advance and then joining these divided molded parts together.

Methods of joining such divided resin molded products together include mechanical joining, adhesive joining, and welding. Among these, welding is a joining method with high productivity, and there are various methods depending on the method of heating the joining material. Specific methods include ultrasonic welding, vibration welding, heat welding, hot air welding, induction welding, and injection welding. Of these welding methods, ultrasonic welding in particular is widely used because of its excellent reproducibility and productivity.

Regarding ultrasonic bonding, for example, Patent Documents 1 and 2 disclose a technology for ultrasonic welding in which a thermoplastic sheet material having functional groups and a bundle of reinforcing fibers are interposed between a molded body made by molding a thermoplastic resin composition and a thermoplastic resin of a different type from the thermoplastic resin of the molded body. Patent Document 3 also discloses a technology for ultrasonic welding of the two welded members by inserting an intermediate layer between the members to be welded and fixing this intermediate layer to an ultrasonic resonator horn and vibrating it.

JP 2017-202667 A JP 2017-206014 A JP 2008-284862 A

In ultrasonic welding, welding occurs due to entanglement and crystallization caused by molecular diffusion at the bonding interface heated by ultrasonic vibration. However, the ultrasonic welding methods described in Patent Documents 1 to 3 have the problem that the entanglement and crystallization caused by molecular diffusion are insufficient, making it difficult to obtain sufficient bonding strength.
Ultrasonic welding is a joining method generally used for joining resins to resins, but compared to other types of welding, ultrasonic welding has advantages such as low power consumption and low cost, ease of automation and control, and particularly excellent productivity and reproducibility, and no unpleasant odor is generated during welding, making it environmentally friendly. Therefore, there has been a demand for a manufacturing method that can join dissimilar materials such as resin and metal, glass, and ceramics with sufficient joining strength by ultrasonic welding.

The present invention has been made in view of these circumstances, and aims to provide a method for manufacturing a joined body that can join the same type of resin and different types of resin with sufficient joining strength by ultrasonic welding, and the joined body. It also aims to provide a method for manufacturing a joined body that can join a resin and at least one material selected from metal, glass, and ceramics with sufficient joining strength by ultrasonic welding, and the joined body.

That is, the present invention provides the following means.
[1] A method for producing a bonded body obtained by bonding a first resin and a second resin, comprising the steps of:
A step of forming a primer layer (A) on a surface of the first resin by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5° C. lower than the softening point of the first resin or a temperature 5° C. lower than the melting point of the first resin;
a step of welding the primer layer (A) to the second resin by ultrasonic welding.
[2] A step of forming a primer layer (B) on a surface of the second resin by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5° C. lower than the softening point of the second resin or a temperature 5° C. lower than the melting point of the second resin,
The method for producing a joined body according to the above-mentioned [1], wherein the welding step includes welding the primer layer (A) and the primer layer (B) by ultrasonic welding.
[3] A method for producing a bonded body obtained by bonding a first resin to at least one material selected from metal, glass, and ceramics, comprising the steps of:
A step of forming a primer layer (A) on a surface of the first resin by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5° C. lower than the softening point of the first resin or a temperature 5° C. lower than the melting point of the first resin;
forming a primer layer (C) on the material using at least one selected from a thermoplastic resin composition and a thermoplastic resin;
A method for producing a bonded body, comprising: a step of welding the primer layer (A) and the primer layer (C) by ultrasonic welding.
[4] The method for producing a joined body according to any one of the above [1] to [3], wherein the step of forming the primer layer (A) comprises heating an in situ polymerization type thermoplastic resin composition on a surface of the first resin to a temperature that is 5° C. lower than the softening point of the first resin or a temperature that is 5° C. lower than the melting point of the first resin, thereby polymerizing the composition to form a primer layer (A) containing a thermoplastic resin.
[5] The method for producing a joined body according to the above-mentioned [2], wherein the step of forming the primer layer (B) comprises heating an in situ polymerization type thermoplastic resin composition on a surface of the second resin to a temperature that is 5° C. lower than the softening point of the second resin or a temperature that is 5° C. lower than the melting point of the second resin, thereby polymerizing the composition to form the primer layer (B).
[6] The method for producing a joined body according to the above-mentioned [3], wherein the step of forming the primer layer (C) comprises polymerizing an in situ polymerization type thermoplastic resin composition on the material to form the primer layer (C).
[7] The method for producing a joint body according to any one of the above [1] to [6], wherein a joint surface of the first resin on the primer layer (A) side is subjected to one or more surface treatments selected from a degreasing treatment, a sanding treatment, a plasma treatment, a corona discharge treatment, and a UV ozone treatment.
[8] The method for producing a joint body according to the above-mentioned [1], wherein the joint surface of the second resin on the primer layer (A) side is subjected to one or more surface treatments selected from a degreasing treatment, a sanding treatment, a plasma treatment, a corona discharge treatment, and a UV ozone treatment.
[9] The method for producing a joint body according to the above [2] or [5], wherein a joint surface of the second resin on the side of the primer layer (B) is subjected to one or more surface treatments selected from a degreasing treatment, a sanding treatment, a plasma treatment, a corona discharge treatment, and a UV ozone treatment.
[10] The method for producing a joint body according to the above [3] or [6], wherein the joint surface of the material on the primer layer (C) side is subjected to one or more surface treatments selected from a degreasing treatment, a sanding treatment, a plasma treatment, a corona discharge treatment, a UV ozone treatment, and a functional group imparting treatment.
[11] The method for producing a joined body according to any one of the above [4] to [6], wherein the in situ polymerization type thermoplastic resin composition contains at least one selected from the following (a) to (g):
(a) a combination of a bifunctional isocyanate compound and a diol; (b) a combination of a bifunctional isocyanate compound and a bifunctional amino compound; (c) a combination of a bifunctional isocyanate compound and a bifunctional thiol compound; (d) a combination of a bifunctional epoxy compound and a diol; (e) a combination of a bifunctional epoxy compound and a bifunctional carboxy compound; (f) a combination of a bifunctional epoxy compound and a bifunctional thiol compound; and (g) a combination of a radically polymerizable monofunctional monomer. [12] The method for producing a joined body according to the above [11], wherein the in-situ polymerization type thermoplastic resin composition further contains a maleic anhydride modified polyolefin.
[13] The method for producing a joined body according to any one of the above [3], [6] and [10], further comprising applying a solution containing at least any one selected from the following (c1) to (c7) to the material to form a functional group-imparting treated surface, and then forming a primer layer (C) on the functional group-imparting treated surface:
(c1) a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group; (c2) a silane coupling agent having an amino group, and at least one compound selected from the group consisting of an epoxy compound and a thiol compound; (c3) a silane coupling agent having a mercapto group, and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) a silane coupling agent having a (meth)acryloyl group, and a thiol compound; (c5) a silane coupling agent having an epoxy group, and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having an amino group and a (meth)acryloyl group; (c6) an isocyanate compound. (c7) Thiol compound [14] The method for producing a joined body according to any one of the above-mentioned [1] to [6], wherein the step of forming the primer layer (A) comprises heating at least one selected from a thermoplastic resin composition and a thermoplastic resin on a surface of the first resin to a temperature not higher than 15° C. higher than the softening point of the first resin or not higher than 5° C. higher than the melting point of the first resin to form the primer layer (A).
[15] The method for producing a joined body according to the above [2] or [5], wherein the step of forming the primer layer (B) comprises heating at least one selected from a thermoplastic resin composition and a thermoplastic resin on a surface of the second resin to a temperature not higher than 15° C. higher than the softening point of the second resin or not higher than 5° C. higher than the melting point of the second resin to form the primer layer (B).
[16] A bonded body obtained by the method for producing a bonded body according to any one of [1] to [15] above.

According to the method for producing a joined body of the present invention, it is possible to join the same type of resin and different types of resin with sufficient joining strength by ultrasonic welding, and also possible to join a resin and at least one material selected from metal, glass, and ceramics with sufficient joining strength by ultrasonic welding.
Therefore, according to the present invention, it is possible to provide a joined body in which the same type of resin and different types of resin are joined with sufficient joining strength by ultrasonic welding, as well as a joined body in which a resin is joined to at least one material selected from metal, glass, and ceramics.

Hereinafter, an embodiment of the method for producing a bonded body and the bonded body of the present invention will be described.
The definitions of each term in this specification are as follows:
"Bonding" means joining two objects together, and welding and adhesion are subordinate concepts. "Welding" means heating the joining surfaces of joining materials such as resin, metal, glass, and ceramics to a temperature exceeding the softening point or melting point of the components present on at least one of the joining surfaces, and joining them by entanglement or crystallization due to molecular diffusion when contacting and pressing and cooling. "Bonding" means joining the adherends together using an organic material such as tape or adhesive (thermosetting resin, thermoplastic resin, etc.).
"(Meth)acryloyl" means acryloyl and/or methacryloyl. Similarly, "(meth)acrylic" means acrylic and/or methacrylic, and "(meth)acrylate" means acrylate and/or methacrylate.
"Normal temperature" means a general room temperature within the range of 5 to 30°C.

[Method of manufacturing the bonded body]
A manufacturing method of a joined body according to one aspect of the present embodiment is a manufacturing method of a joined body obtained by joining a first resin and a second resin, and includes a step of forming a primer layer (A) on a surface of the first resin by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature that is 5° C. lower than the softening point of the first resin or a temperature that is 5° C. lower than the melting point of the first resin or higher, and a step of welding the primer layer (A) to the second resin by ultrasonic welding.
In this embodiment, ultrasonic welding refers to heating the joining surfaces of joining materials such as resin, metal, glass, and ceramics to a temperature above the softening point or melting point of a component present on at least one of the joining surfaces by ultrasonic vibration, and joining the materials by entanglement or crystallization due to molecular diffusion upon contact pressure and cooling.

In the method for producing a joint body according to one aspect of the present embodiment, the primer layer (A) of the first resin and the second resin may be welded by ultrasonic welding without forming a primer layer on the second resin. Alternatively, before the ultrasonic welding, a primer layer (B) may be formed on the surface of the second resin, and the primer layer (A) and the primer layer (B) may be welded by ultrasonic welding. That is, the method for producing a joint body according to one aspect of the present embodiment includes a step of forming a primer layer (B) on the surface of the second resin by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the second resin material or a temperature 5°C lower than the melting point of the second resin material, and the welding step may be a step of welding the primer layer (A) and the primer layer (B) by ultrasonic welding.

A method for producing a bonded body according to another aspect of this embodiment is a method for producing a bonded body formed by bonding a first resin and at least one material selected from metal, glass, and ceramics, and includes the steps of forming a primer layer (A) on the surface of the first resin by heating at least one material selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the first resin or 5°C lower than the melting point of the first resin, forming a primer layer (C) on the material using at least one material selected from a thermoplastic resin composition and a thermoplastic resin, and welding the primer layer (A) and the primer layer (C) by ultrasonic welding.

<First Resin and Second Resin>
The first resin and the second resin may be the same type of resin or different types of resin.
The first resin and the second resin are not particularly limited, but are preferably thermoplastic resins.
The thermoplastic resin may be a general synthetic resin, for example, general-purpose resins such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), etc.; polyester resins such as polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.; polyamide resins such as polyamide 6 (PA6), polyamide 66 (PA66), etc.; general-purpose engineering plastics such as polyacetal (POM), modified polyphenylene ether (m-PPE), etc.; super engineering plastics such as polyetherimide (PEI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyamide imide (PAI), polysulfone (PSU), liquid crystal polymer (LCP), etc. The thermoplastic resin is not particularly limited, but from the viewpoint of obtaining sufficient bonding strength, PP, PC, PBT, PA6, PA66, PEI, and PPS are preferable.

The first resin and the second resin may be composed of only resin, or may be fiber-reinforced plastic (FRP) reinforced with glass fiber or carbon fiber.
The first resin and the second resin are preferably preformed bodies, and may be formed as coating films. Examples of the form of the resin include bulk, film, sheet, FRP molded body, etc. One type selected from these may be used, or a composite of two or more types may be used.

The manufacturing method and molding method of the first resin and the second resin are not particularly limited, and in this embodiment, resins obtained by known methods can be applied. The first resin and the second resin may contain additives such as colorants such as pigments, fillers, antioxidants, and ultraviolet protection agents.

In this embodiment, when the first resin and the second resin are thermoplastic resins, and the first resin is a thermoplastic resin material made of the same type of thermoplastic resin as the thermoplastic resin constituting the second resin, the present invention is suitable for applications in which the first resin and the second resin are firmly welded together. In addition, when the first resin is a thermoplastic resin material made of a different type of thermoplastic resin from the thermoplastic resin constituting the second resin, the SP values of the first resin and the second resin are generally far apart, but the present invention is also suitable for applications in which such different types of thermoplastic resin materials are firmly welded together.
In this specification, "same kind of thermoplastic resin" means a thermoplastic resin in which the monomers constituting the thermoplastic resin are the same and the contents of the monomers are 70 mass% or more. "Different kinds of thermoplastic resin" means a thermoplastic resin other than "same kind of thermoplastic resin", specifically, a thermoplastic resin in which a common monomer does not exist, a thermoplastic resin in which the monomers constituting the thermoplastic resin are different in the maximum content, or a thermoplastic resin in which the monomers constituting the maximum content are the same and at least one of the monomers constituting the maximum content is less than 70 mass%.

<Metal>
The metal is not particularly limited, and examples thereof include aluminum, iron, copper, magnesium, and titanium.
In this embodiment, the term "iron" is used to include iron and its alloys. Examples of iron alloys include steel and stainless steel. Similarly, copper, aluminum, magnesium, and titanium are used to include their simple substances and alloys.
Among these, aluminum is preferred from the viewpoint of reducing the weight of the resulting joined body.

<Glass>
The glass is not particularly limited, and may be general glass, heat-resistant glass, fireproof glass, fire-resistant glass, chemically strengthened glass used for protecting smartphones, etc. Specific examples include soda-lime glass, lead glass, borosilicate glass, and quartz glass.

<Ceramics>
The ceramics are not particularly limited, and examples thereof include fine ceramics used in semiconductors, automobiles, industrial equipment, etc. Specific examples thereof include oxide-based ceramics such as alumina, zirconia, barium titanate, etc.; hydroxide-based ceramics such as hydroxyapatite, carbide-based ceramics such as silicon carbide, and nitride-based ceramics such as silicon nitride.

[Surface treatment]
From the viewpoint of improving the bonding strength by cleaning and anchoring effect, the bonding surfaces of the first resin, the second resin, the metal, the glass, and the ceramics on which the primer layers (A) to (C) are formed may be subjected to a surface treatment before forming the primer layers (A) to (C). In particular, when the primer layer (C) is formed on the surface of materials such as metal, glass, and ceramics, the bonding between the material and the primer layer (C) is likely to be good, which can indirectly contribute to improving the bonding strength between the first resin and the material.

Examples of the surface treatment include cleaning with a solvent or the like, degreasing treatment, blasting treatment, polishing treatment such as sanding, plasma treatment, corona discharge treatment, UV ozone treatment, laser treatment, etching treatment, boehmite treatment, and functional group imparting treatment, and the like can be appropriately selected depending on the material of the bonding material.
In the first resin, the joining surface on the primer layer (A) side is preferably subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment and UV ozone treatment.
In the second resin, the joining surface on the primer layer (A) side is preferably subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment and UV ozone treatment.
In addition, it is also preferable that the bonding surface of the second resin on the primer layer (B) side is subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment and UV ozone treatment.
In the case of materials such as metals, glasses and ceramics, it is preferable to subject the joining surface on the primer layer (C) side to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment and UV ozone treatment.
The surface treatment may be performed by one type alone or in combination of two or more types. As the specific method for the surface treatment, a known method can be applied.

(Functional Group Addition Treatment)
The functional group imparting treatment is a treatment for imparting a functional group to the surface of metal, glass, or ceramic. The joining surface of the metal, glass, or ceramic on the primer layer (C) side is preferably subjected to the functional group imparting treatment in order to obtain sufficient joining strength. When the functional group imparting treatment is performed in combination with a surface treatment other than the above-mentioned functional group imparting treatment, it is preferable to perform the functional group imparting treatment after performing a surface treatment other than the functional group imparting treatment.

From the viewpoint of obtaining sufficient bonding strength, the bonding surface of the metal, glass, or ceramic on the side of the primer layer (C) is preferably a surface (functional group-imparting treated surface) imparted with at least one functional group selected from the following (C1) to (C7) by functional group imparting treatment:
(C1) At least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group derived from a silane coupling agent. (C2) A functional group generated by the reaction of an amino group derived from a silane coupling agent with at least one compound selected from the group consisting of an epoxy compound and a thiol compound. (C3) A functional group generated by the reaction of a mercapto group derived from a silane coupling agent with at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group. (C4) A functional group generated by the reaction of a (meth)acryloyl group derived from a silane coupling agent with a thiol compound. (C5) A functional group generated by the reaction of an epoxy group derived from a silane coupling agent with at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having an amino group and a (meth)acryloyl group. (C6) An isocyanato group derived from an isocyanate compound. (C7) A mercapto group derived from a thiol compound.

The functional group-imparted treated surface, which is the surface to which functional groups have been imparted, preferably contains a functional group among the functional groups (C1) to (C7) above that is reactive with the functional group contained in the thermoplastic resin composition or thermoplastic resin forming the primer layer (C). These functional groups may be of one type alone or may contain two or more types.
Examples of the functional group present on the functional group-imparting treated surface include an epoxy group, an amino group, a mercapto group, an isocyanato group, a carboxy group, a hydroxyl group, and a (meth)acryloyl group.

Examples of the silane coupling agents having an epoxy group in (C1) and (C5) include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.
Examples of the silane coupling agent having an amino group in (C1) and (C2) include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane.
Examples of the silane coupling agents having a (meth)acryloyl group in (C1) and (C4) include 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane.
Examples of the silane coupling agent having a mercapto group in (C1) and (C3) include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and the like.

The epoxy compounds in (C2) and (C3) are not limited to silane coupling agents, and examples of such compounds include the bifunctional epoxy compounds in the in-situ polymerized thermoplastic resin compositions described below.

The thiol compounds in (C2), (C4), (C5) and (C7) are those other than silane coupling agents, and examples thereof include dithiol compounds in the in situ polymerization type thermoplastic resin composition described later.
The amino compounds in (C3) and (C5) are those other than silane coupling agents and include, for example, the in situ polymerization type thermoplastic resin composition diamino compounds described later.
As the isocyanate compound in the functional groups (C3) and (C6), other than the silane coupling agent, for example, a diisocyanate compound in the in-situ polymerization type thermoplastic resin composition described later can be mentioned.

An example of the compound (C3) having an epoxy group and a (meth)acryloyl group is glycidyl (meth)acrylate.
Examples of the compounds having an amino group and a (meth)acryloyl group in (C3) and (C5) include (meth)acrylamide.

From the viewpoint of obtaining sufficient bonding strength, it is preferable that, for metals, glasses, and ceramics, a solution containing at least any one selected from the following (c1) to (c7) is applied to form a functional group-imparting treated surface, and then a primer layer (C) is formed on the functional group-imparting treated surface:
(c1) a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group; (c2) a silane coupling agent having an amino group, and at least one compound selected from the group consisting of an epoxy compound and a thiol compound; (c3) a silane coupling agent having a mercapto group, and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) a silane coupling agent having a (meth)acryloyl group, and a thiol compound; (c5) a silane coupling agent having an epoxy group, and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having an amino group and a (meth)acryloyl group; (c6) an isocyanate compound; (c7) a thiol compound.

The compounds (c1) to (c7) correspond to the functional groups (C1) to (C7) described above, respectively, and generate these functional groups. That is, a functional group-imparting treatment surface containing the functional group of (C1) can be formed by a functional group imparting treatment using a solution containing (c1). The same applies to (c2) to (c7).
For example, in the treatment of (c2), when a dithiol compound is reacted with an amino group, a mercapto group, which is a functional group of the dithiol compound, is introduced to the terminal.Similarly, in the treatment of (c3), when a polyfunctional isocyanate compound is reacted with a mercapto group, an isocyanato group, which is a functional group of the polyfunctional isocyanate compound, is introduced to the terminal.

When a primer layer (C) is formed on a functional group-imparted surface of metal, glass, or ceramic, the functional groups (C1) to (C7) on the functional group-imparted surface react with the functional groups of the compounds that make up the primer layer (C), making it impossible to confirm their presence. In addition, the functional groups generated using each compound (c1) to (c7) are not limited to one type, and may be diverse. In view of this situation, in this invention, based on the well-known technology that a specific functional group is generated by the reaction of specific functional groups with each other and the inference based thereon, it is assumed that a functional group-imparted surface having a specific functional group is formed by performing a functional group imparting process using a compound having a specific functional group, and is therefore represented as (C1) to (C7) and (c1) to (c7).

The method for applying the solution containing at least one selected from (c1) to (c7) is not particularly limited, and for example, a dipping method, a spraying method, or the like can be used.
In the case of the immersion method, for example, metal, glass, and ceramics are immersed in the solution having a concentration of about 0.5 to 50% by mass at 20 to 100° C. for 1 minute to 5 days, and then pulled out and dried at room temperature to 100° C. for 1 minute to 5 hours, thereby forming a functional group-imparting treated surface.
In the case of the spray method, for example, the solution having a concentration of about 0.5 to 50% by mass is sprayed onto metal, glass, or ceramics, and then dried at room temperature to 100° C. for 1 minute to 5 hours, thereby forming a functional group-imparting treated surface.

<Step of forming primer layer (A)>
The step of forming the primer layer (A) in this embodiment is a step of heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the first resin or a temperature 5°C lower than the melting point of the first resin on the surface of the first resin to form the primer layer (A). In addition, the primer layer (A) in one aspect of this embodiment refers to a layer containing a thermoplastic resin that is in contact with the first resin and is interposed between the second resin that is bonded to the first resin, and can bond the first resin and the second resin by ultrasonic welding. In addition, the primer layer (A) in another aspect of this embodiment refers to a layer containing a thermoplastic resin that is interposed between the first resin and at least one material selected from metal, glass, and ceramics, and can bond the first resin and the material by ultrasonic welding.
From the viewpoint of improving the bonding strength between the first resin and the primer layer (A), from the viewpoint of bonding the first resin and the second resin with sufficient bonding strength, and from the viewpoint of bonding the first resin and a material with sufficient bonding strength, it is preferable to form the primer layer (A) by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin on the surface of the first resin that has been subjected to the above-mentioned surface treatment to a temperature that is 5° C. lower than the softening point of the first resin or a temperature that is 5° C. lower than the melting point of the first resin.

In this embodiment, by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the first resin or a temperature 5°C lower than the melting point of the first resin to form the primer layer (A), molecular diffusion occurs between the primer layer (A) and the first resin, and it becomes possible to form the primer layer (A) firmly bonded to the first resin. As a result, it becomes possible to bond the first resin and the second resin, and the first resin and the material with sufficient bonding strength.
When at least one selected from the thermoplastic resin composition and the thermoplastic resin is heated at a temperature 5 ° C lower than the softening point of the first resin or at a temperature 5 ° C lower than the melting point, when the first resin is an amorphous resin, from the viewpoint of obtaining sufficient bonding strength, the temperature is preferably 4 ° C lower than the softening point of the first resin, more preferably 3 ° C lower than the softening point, and even more preferably 2 ° C lower than the softening point. From the viewpoint of suppressing deformation of the first resin due to heat, the temperature is preferably 15 ° C higher than the softening point, more preferably 10 ° C higher than the softening point, and even more preferably 8 ° C higher than the softening point. When the first resin is a crystalline resin, from the viewpoint of obtaining sufficient bonding strength, the temperature is preferably 4 ° C lower than the melting point of the first resin, more preferably 3 ° C lower than the melting point, and even more preferably 2 ° C lower than the melting point. From the viewpoint of suppressing deformation of the first resin due to heat, the temperature is preferably 5 ° C higher than the melting point, more preferably 3 ° C higher than the melting point, and even more preferably 1 ° C higher than the melting point.

The heating time when at least one selected from the thermoplastic resin composition and the thermoplastic resin is heated at a temperature equal to or higher than the softening point or melting point of the first resin is preferably 1 second to 30 minutes, more preferably 30 seconds to 20 minutes, and even more preferably 1 to 15 minutes, from the viewpoint of suppressing deformation of the first resin due to heat.

The primer layer (A) may be a layer obtained by heating a thermoplastic resin composition, or may be a layer made of a thermoplastic resin.
When the primer layer (A) is a layer obtained by heating a thermoplastic resin composition, the primer layer (A) can be formed, for example, by applying a solution containing the thermoplastic resin composition and a solvent to the surface of a first resin, volatilizing the solvent, and then heating to a temperature equal to or higher than the softening point or melting point of the first resin to polymerize the monomer.
When the primer layer (A) is a layer made of a thermoplastic resin, it can be formed, for example, by arranging a film-like thermoplastic resin so as to be in contact with a first resin, and then heating the surface of the first resin to a temperature equal to or higher than the softening point or melting point of the first resin.

In this embodiment, from the viewpoint of obtaining sufficient bonding strength, it is preferable that the primer layer (A) is a layer obtained by heating a thermoplastic resin composition, and it is more preferable that the thermoplastic resin composition is an in-situ polymerization type thermoplastic resin composition described later.
In addition, from the viewpoint of obtaining sufficient bonding strength, the step of forming the primer layer (A) is preferably a step of forming the primer layer (A) by heating an in-situ polymerization type thermoplastic resin composition on the surface of the first resin to a temperature that is 5° C. lower than the softening point of the first resin or a temperature that is 5° C. lower than the melting point of the first resin, thereby polymerizing the composition.
The thermoplastic resin composition is an in situ polymerization type thermoplastic resin composition, and the in situ polymerization type thermoplastic resin composition is heated to a temperature 5°C lower than the softening point of the first resin or 5°C lower than the melting point of the first resin to polymerize the composition on the surface of the first resin, thereby improving the bonding strength between the first resin and the entire first resin side of the primer layer (A). Furthermore, even if ultrasonic vibration is not transmitted to the bonding surface between the first resin and the primer layer (A) during ultrasonic welding, the first resin and the primer layer (A) are already firmly bonded together, so that it is possible to obtain a bonded body with excellent bonding strength without any portion having inferior bonding strength.

In this embodiment, from the viewpoint of suppressing deformation of the first resin due to heat, before the in situ polymerization type thermoplastic resin composition is heated to a temperature equal to or higher than 5° C. lower than the softening point or melting point of the first resin to polymerize it, the in situ polymerization type thermoplastic resin composition may be preheated on the surface of the first resin at a temperature lower than 5° C. lower than the softening point or lower than 5° C. lower than the melting point of the first resin to polymerize it.
When the first resin is heated to polymerize at a temperature less than 5°C lower than the softening point or less than 5°C lower than the melting point, if the first resin is a non-crystalline resin, the temperature may be less than 5°C lower than the softening point of the first resin as long as it is a temperature required for polymerization, and if the first resin is a crystalline resin, the temperature may be less than 5°C lower than the melting point of the first resin as long as it is a temperature required for polymerization.
The heating time when polymerizing by heating at a temperature less than 5° C. lower than the softening point or less than 5° C. lower than the melting point of the first resin is preferably 1 to 60 minutes, more preferably 10 to 50 minutes, and even more preferably 15 to 45 minutes, from the viewpoint of suppressing deformation of the first resin due to heat.
Specifically, for example, when the first resin is PA6 having a melting point of 225°C, the in-situ polymerization type thermoplastic resin composition may be polymerized on the surface of the PA6 at 40 to 180°C for 1 to 30 minutes, and then further polymerized at 220 to 230°C for 1 second to 30 minutes.
In addition, in the case of a resin having a relatively low softening point or melting point, for example, 150° C. or lower, the in-situ polymerization type thermoplastic resin composition may not be polymerized by heating at a temperature less than 5° C. lower than the softening point or less than 5° C. lower than the melting point of the first resin, but may be polymerized only by heating at a temperature equal to or higher than 5° C. lower than the softening point or 5° C. lower than the melting point of the first resin.
In this embodiment, it is preferable to carry out polymerization of the in-situ polymerization type thermoplastic resin composition using as a guide the softening point and melting point temperatures of the resin shown in the following Table 1. The softening point is a value (Vicat softening temperature) obtained by measurement in accordance with ISO 306 (2013), and the melting point is a value obtained by measurement in accordance with ISO 11357-3 (2011).

When the thermoplastic resin composition is an in-situ polymerization type thermoplastic resin composition, the primer layer (A) can be obtained by applying a solution containing the in-situ polymerization type thermoplastic resin composition and a solvent to the surface of the first resin, volatilizing the solvent, and then heating the in-situ polymerization type thermoplastic resin composition at a temperature equal to or higher than the softening point or melting point of the first resin to polymerize it.
The coating method for forming the primer layer (A) is not particularly limited, and for example, a dipping method, a spray coating method, etc. can be used.
In the case of the immersion method, for example, the first resin is immersed in a solution having a concentration of about 0.5 to 50 mass% of the in-situ polymerization type thermoplastic resin composition at room temperature to 100° C. for 1 minute to 5 days, and then dried at a temperature within a range of room temperature to 100° C. for 1 minute to 5 hours. Thereafter, the in-situ polymerization type thermoplastic resin composition is heated at a temperature that is 5° C. lower than the softening point of the first resin or at least 5° C. lower than the melting point of the first resin, for a heating time, to polymerize the in-situ polymerization type thermoplastic resin composition, thereby forming the primer layer (A).

In the case of the spray method, for example, a solution having a concentration of about 0.5 to 50% by mass of the in-situ polymerization type thermoplastic resin composition is sprayed onto the first resin, and dried at a temperature within the range of room temperature to 100°C for 1 minute to 5 hours. The in-situ polymerization type thermoplastic resin composition is then heated and polymerized at a temperature and for a heating time that is at least 5°C lower than the softening point or at least 5°C lower than the melting point of the first resin described above, thereby forming the primer layer (A).

Alternatively, a solution in which the in situ polymerization type thermoplastic resin composition is dissolved in a solvent may be applied onto a release film, and the solvent may be volatilized in an environment of room temperature to 40° C. to form a partially polymerized film. The film may then be placed in contact with a first resin, and the release film may be peeled off. The polymerization of the in situ polymerization type thermoplastic resin composition in the film may be further advanced on the surface of the first resin at a temperature that is 5° C. lower than the softening point or 5° C. lower than the melting point of the first resin or more for a heating time period to form a primer layer (A).
Alternatively, the primer layer (A) can be formed by applying the in-situ polymerized thermoplastic resin composition in the form of a powder or emulsion to the surface of the first resin, and polymerizing the composition by heating at a temperature that is 5° C. lower than the softening point of the first resin or at least 5° C. lower than the melting point of the first resin, for a heating time. As the powder, for example, the film obtained by pulverizing the film can be used in the form of a powder paint, or the pulverized film can be emulsified in water or the like using an emulsifier to form the emulsion.

The thickness of the primer layer (A) depends on the type of the first resin and the contact area of the joint, but in order to obtain sufficient joint strength and to prevent thermal deformation of the resulting joint due to the difference in thermal expansion coefficient between the first resin and the second resin, and the difference in thermal expansion coefficient between the first resin and the material, it is preferably 1 μm to 1 mm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 60 μm.

<Step of forming primer layer (B)>
The step of forming the primer layer (B) in this embodiment is a step of heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the second resin or a temperature 5°C lower than the melting point of the second resin on the surface of the second resin to form the primer layer (B). The primer layer (B) in this embodiment refers to a layer that is in contact with the second resin and is interposed between the first resin that is bonded to the second resin together with the primer layer (A), and can bond the second resin and the first resin by ultrasonic welding. From the viewpoint of improving the bonding strength between the second resin and the primer layer (B) and from the viewpoint of bonding the first resin and the second resin with sufficient bonding strength, it is preferable to form the primer layer (B) by heating at least one selected from a thermoplastic resin composition and a thermoplastic resin to a temperature 5°C lower than the softening point of the second resin or a temperature 5°C lower than the melting point of the second resin on the surface of the second resin that has been subjected to the above-mentioned surface treatment.

In this embodiment, at least one selected from the thermoplastic resin composition and the thermoplastic resin is heated to a temperature 5°C lower than the softening point of the second resin or 5°C lower than the melting point of the second resin, whereby molecular diffusion occurs between the primer layer (B) and the second resin, making it possible to form a primer layer (B) that is firmly bonded to the second resin. In this way, by forming the primer layer (B) on the surface of the second resin and welding the primer layer (A) and the primer layer (B), a bonded body with improved bonding strength can be obtained.

When the second resin is a non-crystalline resin, the temperature at which the second resin is heated to a temperature 5°C lower than the softening point or 5°C lower than the melting point is preferably 4°C lower than the softening point of the second resin, more preferably 3°C lower than the softening point, and even more preferably 2°C lower than the softening point, from the viewpoint of obtaining sufficient bonding strength; and preferably 15°C higher than the softening point, more preferably 10°C higher than the softening point, and even more preferably 8°C higher than the softening point, from the viewpoint of suppressing deformation of the second resin due to heat; when the second resin is a crystalline resin, the temperature is preferably 4°C lower than the melting point of the second resin, more preferably 3°C lower than the melting point, and even more preferably 2°C lower than the melting point, from the viewpoint of obtaining sufficient bonding strength; and preferably 5°C higher than the melting point, more preferably 3°C higher than the melting point, and even more preferably 1°C higher than the melting point, from the viewpoint of suppressing deformation of the second resin due to heat.

The heating time when the in-situ polymerized thermoplastic resin composition is heated to a temperature 5°C lower than the softening point of the second resin or 5°C lower than the melting point of the second resin is preferably 1 second to 30 minutes, more preferably 30 seconds to 20 minutes, and even more preferably 1 to 15 minutes, from the viewpoint of obtaining sufficient bonding strength and suppressing deformation of the second resin due to heat.

The primer layer (B) may be a layer obtained by heating a thermoplastic resin composition, or may be a layer made of a thermoplastic resin.
When the primer layer (B) is a layer obtained by heating a thermoplastic resin composition, the primer layer (B) can be formed, for example, by applying a solution containing the thermoplastic resin composition and a solvent to the surface of the second resin, volatilizing the solvent, and then heating to a temperature that is 5° C. lower than the softening point of the second resin or a temperature that is 5° C. lower than the melting point of the second resin.
When the primer layer (B) is a layer made of a thermoplastic resin, it can be formed, for example, by arranging a film-like thermoplastic resin so as to be in contact with a second resin, and then heating the surface of the second resin to a temperature that is 5° C. lower than the softening point of the second resin or a temperature that is 5° C. lower than the melting point of the second resin.

In this embodiment, from the viewpoint of obtaining sufficient bonding strength, it is preferable that the primer layer (B) is a layer obtained by heating a thermoplastic resin composition, and it is more preferable that the thermoplastic resin composition is an in-situ polymerization type thermoplastic resin composition described later.
In addition, from the viewpoint of obtaining sufficient bonding strength, the step of forming the primer layer (B) is preferably a step of forming the primer layer (B) by heating and polymerizing an in-situ polymerization type thermoplastic resin composition on the surface of the second resin to a temperature that is 5° C. lower than the softening point of the second resin or a temperature that is 5° C. lower than the melting point of the second resin.
When the thermoplastic resin composition is an in situ polymerization type thermoplastic resin composition, and the in situ polymerization type thermoplastic resin composition is heated to a temperature 5°C lower than the softening point of the second resin or 5°C lower than the melting point of the second resin to polymerize the composition on the surface of the second resin, the bonding strength between the second resin and the entire second resin side of the primer layer (B) is improved. In addition, even if ultrasonic vibration is not transmitted to the bonding surface between the second resin and the primer layer (B) during ultrasonic welding, the second resin and the primer layer (B) are already firmly bonded to each other, so that a bonded body having excellent bonding strength without any portions having inferior bonding strength can be obtained.

In this embodiment, from the viewpoint of suppressing deformation of the second resin due to heat, before the in-situ polymerization type thermoplastic resin composition is heated to a temperature that is 5° C. lower than the softening point or 5° C. lower than the melting point of the second resin or more to polymerize it, similar to the first resin, the in-situ polymerization type thermoplastic resin composition may be pre-heated on the surface of the second resin at a temperature that is less than 5° C. lower than the softening point or less than 5° C. lower than the melting point of the second resin to polymerize it.
When the second resin is heated to polymerize at a temperature less than 5°C lower than the softening point or less than 5°C lower than the melting point, if the second resin is a non-crystalline resin, the temperature may be less than 5°C lower than the softening point of the second resin as long as it is a temperature required for polymerization, and if the second resin is a crystalline resin, the temperature may be less than 5°C lower than the melting point of the second resin as long as it is a temperature required for polymerization.
The heating time when polymerizing by heating at a temperature less than 5° C. lower than the softening point or less than 5° C. lower than the melting point of the second resin is preferably 1 to 60 minutes, more preferably 10 to 50 minutes, and even more preferably 15 to 45 minutes, from the viewpoint of suppressing deformation of the second resin due to heat.
In this embodiment, it is preferable to carry out polymerization of the in situ polymerization type thermoplastic resin composition using the softening point and melting point of the resin shown in Table 1 as a guide for the second resin as well as the first resin.

When the thermoplastic resin composition is an in situ polymerization type thermoplastic resin composition, the primer layer (B) can be obtained by applying a solution containing the in situ polymerization type thermoplastic resin composition and a solvent to the surface of the second resin, volatilizing the solvent, and polymerizing the in situ polymerization type thermoplastic resin composition at a temperature that is 5°C lower than the softening point of the second resin or a temperature that is 5°C lower than the melting point of the second resin or a temperature that is 5°C lower than the melting point of the second resin.
The coating method for forming the primer layer (B) is not particularly limited, and the same coating method as the coating method for forming the primer layer (A) can be used.

In addition, a film in which the above-mentioned partially polymerized in-situ polymerization type thermoplastic resin composition is formed may be placed in contact with a second resin, and then the release film may be peeled off. Polymerization of the in-situ polymerization type thermoplastic resin composition may be further advanced on the surface of the second resin at a temperature that is 5° C. lower than the softening point of the above-mentioned second resin or at least a temperature that is 5° C. lower than the melting point of the second resin, and for a heating time period to form a primer layer (B).
Alternatively, the primer layer (B) can be formed by applying the in-situ polymerized thermoplastic resin composition in the form of a powder or emulsion to the surface of the second resin, and polymerizing the composition at a temperature that is 5° C. lower than the softening point of the second resin or at least 5° C. lower than the melting point of the second resin, for a heating time of 100° C. to 200° C. As the powder, for example, the film obtained by pulverizing the film can be used in the form of a powder coating material, and the pulverized film can be emulsified in water or the like using an emulsifier to form the emulsion.

The thickness of the primer layer (B) depends on the type of second resin and the contact area of the joint, but in order to obtain sufficient joint strength and to prevent the resulting joint from being thermally deformed due to the difference in thermal expansion coefficient between the second resin and the first resin, it is preferably 1 μm to 1 mm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 60 μm.

<Step of forming primer layer (C)>
The step of forming the primer layer (C) in this embodiment is a step of forming the primer layer (C) on at least one material selected from metal, glass, and ceramics using at least one selected from a thermoplastic resin composition and a thermoplastic resin. The primer layer (C) in this embodiment refers to a layer that can be interposed between at least one material selected from metal, glass, and ceramics and a first resin to be bonded together with the primer layer (A), and can bond the material and the first resin by welding the primer layer (A) and the primer layer (C) by ultrasonic welding. From the viewpoint of improving the bonding strength between the material and the primer layer (C) and from the viewpoint of bonding the first resin and the material with sufficient bonding strength, it is preferable to form the primer layer (C) on the surface of the material that has been subjected to the above-mentioned surface treatment, and it is more preferable to form the primer layer (C) on the functional group-imparting treated surface of the material.
The primer layer (C) may be formed in one layer or in two or more layers.

The primer layer (C) may be a layer obtained by using a thermoplastic resin composition, or may be a layer made of a thermoplastic resin.
When the primer layer (C) is a layer obtained by using a thermoplastic resin composition, the primer layer (C) can be formed, for example, by applying a solution containing the thermoplastic resin composition and a solvent onto a material, volatilizing the solvent, and then heating or irradiating with light.
When the primer layer (C) is a layer made of a thermoplastic resin, it can be formed, for example, by arranging a film-like thermoplastic resin so as to be in contact with the material, and then heating the film-like thermoplastic resin.

In this embodiment, from the viewpoint of obtaining sufficient bonding strength, it is preferable that the primer layer (C) is a layer obtained by using a thermoplastic resin composition, and it is more preferable that the thermoplastic resin composition is an in-situ polymerization type thermoplastic resin composition described later.
In addition, from the viewpoint of obtaining sufficient bonding strength, the step of forming the primer layer (C) is preferably a step of forming the primer layer (C) on the material by polymerizing an in-situ polymerization type thermoplastic resin composition.
The thermoplastic resin composition is an in-situ polymerized thermoplastic resin composition, and the in-situ polymerized thermoplastic resin composition is polymerized on the material, thereby improving the bonding strength of the bonded body.

When the thermoplastic resin composition is an in situ polymerized thermoplastic resin composition, the primer layer (C) can be obtained by applying a solution containing the in situ polymerized thermoplastic resin composition and a solvent to the surface of the material, volatilizing the solvent, and polymerizing the in situ polymerized thermoplastic resin composition.
The coating method for forming the primer layer (C) is not particularly limited, and for example, a dipping method, a spray coating method, etc. can be used.
In the case of the immersion method, for example, the concentration of the in-situ polymerization type thermoplastic resin composition is about 0.5 to 50 mass%, and the material is immersed in a solution at room temperature to 100 ° C. for 1 minute to 5 days, then dried at a temperature in the range of room temperature to 100 ° C. for 1 minute to 5 hours, and then heated to a temperature in the range of room temperature to 200 ° C. and left for 5 to 120 minutes to polymerize the in-situ polymerization type thermoplastic resin composition, thereby forming a primer layer (C). When forming the primer layer (C) by photocuring, the material immersed in the solution for 1 minute to 5 days is irradiated with ultraviolet light or visible light at a temperature in the range of room temperature to 100 ° C. for 10 seconds to 60 minutes to polymerize the in-situ polymerization type thermoplastic resin composition, thereby forming the primer layer (C).

In the case of the spray method, for example, a solution having a concentration of about 0.5 to 50% by mass of the in situ polymerization type thermoplastic resin composition is sprayed onto the material, dried at a temperature in the range of room temperature to 100°C for 1 minute to 5 hours, and then left at a temperature in the range of room temperature to 200°C for 5 to 120 minutes to polymerize the in situ polymerization type thermoplastic resin composition, thereby forming the primer layer (C). In the case of forming the primer layer (C) by photocuring, the primer layer (C) can be formed by irradiating the in situ polymerization type thermoplastic resin composition with ultraviolet light or visible light for 10 seconds to 60 minutes at a temperature in the range of room temperature to 100°C to polymerize the in situ polymerization type thermoplastic resin composition.

In addition, the primer layer (C) may be formed by arranging a film in which the above-mentioned partially polymerized in-situ polymerization type thermoplastic resin composition is in contact with the material, peeling off the release film, heating to a temperature in the range of 40 to 150°C, and leaving it for 1 to 30 minutes to further polymerize the in-situ polymerization type thermoplastic resin composition.
Alternatively, the primer layer (C) can be formed by applying the in-situ polymerization type thermoplastic resin composition in the form of a powder or emulsion to the surface of the material so that the thickness after polymerization is 1 to 100 μm, and polymerizing the in-situ polymerization type thermoplastic resin composition. As the powder, for example, the film obtained by pulverizing the film can be used in the form of a powder paint, or the pulverized film can be emulsified in water or the like using an emulsifier to form the emulsion.

The thickness of the primer layer (C) depends on the type of the first resin and material, the contact area of the joint, etc., but in order to obtain sufficient joint strength and to prevent the resulting joint from being thermally deformed due to the difference in thermal expansion coefficient between the first resin and the material, it is preferably 1 μm to 1 mm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 50 μm.

<Thermoplastic resin composition>
The thermoplastic resin composition is not particularly limited, but is preferably an in-situ polymerized thermoplastic resin composition.

[In-situ polymerizable thermoplastic resin composition]
In the present embodiment, the in-situ polymerization type thermoplastic resin composition is a thermoplastic structure, which is formed by reacting a composition containing a predetermined combination of reactive bifunctional compounds on-site, i.e., on various materials. That is, it is a composition that forms a linear polymer structure. The in-situ polymerization type thermoplastic resin composition does not form a three-dimensional network due to a crosslinked structure, unlike a thermosetting resin that forms a three-dimensional network due to a crosslinked structure. First, it is a polymerizable composition having thermoplastic properties.

The in situ polymerization type thermoplastic resin composition preferably contains at least one of the following (a) to (g), more preferably contains the following (d), and further preferably contains a combination of a bifunctional epoxy resin and a bifunctional phenol compound:
(a) A combination of a bifunctional isocyanate compound and a diol (b) A combination of a bifunctional isocyanate compound and a bifunctional amino compound (c) A combination of a bifunctional isocyanate compound and a bifunctional thiol compound (d) A combination of a bifunctional epoxy compound and a diol (e) A combination of a bifunctional epoxy compound and a bifunctional carboxy compound (f) A combination of a bifunctional epoxy compound and a bifunctional thiol compound (g) A monofunctional radically polymerizable monomer

The blend ratio of the bifunctional isocyanate compound and the diol in (a) is set so that the molar equivalent ratio of the isocyanate group to the hydroxyl group is preferably 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.
The blending ratio of the bifunctional isocyanate compound and the bifunctional amino compound in (b) is set so that the molar equivalent ratio of the isocyanate group to the amino group is preferably 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.
The blend ratio of the bifunctional isocyanate compound and the bifunctional thiol compound in (c) is preferably set so that the molar equivalent ratio of the isocyanate group to the thiol group is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.

The blend ratio of the bifunctional epoxy compound and the diol in (d) is set so that the molar equivalent ratio of epoxy groups to hydroxyl groups is preferably 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.
The blending ratio of the bifunctional epoxy compound and the bifunctional carboxy compound in (e) is set so that the molar equivalent ratio of the epoxy group to the carboxy group is preferably 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.
The blending ratio of the bifunctional epoxy compound and the bifunctional thiol compound in (f) is preferably set so that the molar equivalent ratio of the epoxy group to the thiol group is 0.7 to 1.5, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.3.

When the in-situ polymerization type thermoplastic resin composition contains at least one selected from the above (a) to (g), for example, a tertiary amine such as triethylamine or 2,4,6-tris(dimethylaminomethyl)phenol-phosphorus compound such as triphenylphosphine is preferably used as a catalyst for polymerization.

As a polymerization initiator for radical polymerization, for example, a known organic peroxide or photoinitiator is preferably used. A room temperature radical polymerization initiator in which an organic peroxide is combined with a cobalt metal salt or amines may be used. Examples of organic peroxides include those classified as ketone peroxides, peroxyketals, hydroperoxides, diallyl peroxides, diacyl peroxides, peroxy esters, and peroxydicarbonates. It is preferable that the photopolymerization initiator is one that can initiate radical polymerization by irradiation with light in the wavelength range from ultraviolet light to visible light. These may be used alone or in combination of two or more types. Of these, organic peroxides are preferable.

(Difunctional isocyanate compound)
The bifunctional isocyanate compound is a compound having two isocyanato groups, and examples thereof include diisocyanate compounds such as hexamethylene diisocyanate, tetramethylene diisocyanate, dimer acid diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI) or a mixture thereof, p-phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate (MDI), etc. Among these, TDI, MDI, etc. are preferred from the viewpoint of the strength of the primer layer.

(Diol)
The diol is a compound having two hydroxy groups, and examples thereof include aliphatic glycols such as ethylene glycol, propylene glycol, diethylene glycol, and 1,6-hexanediol, and bisphenols such as bisphenol A, bisphenol F, and bisphenol S. Among these, propylene glycol, diethylene glycol, bisphenol A, bisphenol S, etc. are preferred from the viewpoint of the toughness of the primer layer.

(Bifunctional amino compound)
The bifunctional amino compound is a compound having two amino groups, and examples thereof include bifunctional aliphatic diamines and aromatic diamines. Examples of aliphatic diamines include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-diaminobutane, 1,6-hexamethylenediamine, 2,5-dimethyl-2,5-hexanediamine, 2,2,4-trimethylhexamethylenediamine, isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane, 1,3-diaminocyclohexane, and N-aminoethylpiperazine. Examples of aromatic diamines include diaminodiphenylmethane and diaminodiphenylpropane. Among these, 1,3-propanediamine, 1,4-diaminobutane, and 1,6-hexamethylenediamine are preferred from the viewpoint of the toughness of the primer layer.

(Bifunctional thiol compound)
The bifunctional thiol compound is a compound having two mercapto groups in the molecule, and examples thereof include 1,4-bis(3-mercaptobutyryloxy)butane (e.g., Karenz MT (registered trademark) BD1 (manufactured by Showa Denko K.K.)), a bifunctional secondary thiol compound.

(Difunctional epoxy compound)
The bifunctional epoxy compound is a compound having two epoxy groups in one molecule, and examples thereof include aromatic epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenol type epoxy resin, and naphthalene type bifunctional epoxy resin, and aliphatic epoxy compounds such as 1,6-hexanediol diglycidyl ether.
These may be used alone or in combination of two or more.
Specific examples include jER (registered trademark) 828, 834, 1001, 1004, 1007, and YX-4000 (all manufactured by Mitsubishi Chemical Corporation). In addition, epoxy compounds having special structures can also be used as long as they are bifunctional.

(Bifunctional Carboxy Compound)
The bifunctional carboxy compound may be any compound having two carboxy groups, and examples thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, isophthalic acid, terephthalic acid, etc. Among these, isophthalic acid, terephthalic acid, adipic acid, etc. are preferred from the viewpoint of the strength and toughness of the primer layer.

(Monofunctional radically polymerizable monomer)
The monofunctional radical polymerizable monomer is a monomer having one ethylenically unsaturated bond. Examples include styrene monomers, α-, o-, m-, p-alkyl, nitro, cyano, amide, and ester derivatives of styrene, chlorostyrene, vinyltoluene, and divinylbenzene; and (meth)acrylic acid esters such as ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofuryl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate, and glycidyl (meth)acrylate. Of the above compounds, one type may be used, or two or more types may be used. Among these, from the viewpoint of strength and toughness of the primer layer, one or a combination of two or more of styrene, methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and phenoxyethyl (meth)acrylate are preferred.

In order to allow the radical polymerization reaction to proceed sufficiently and form the desired primer layers (A) to (C), a solvent and, if necessary, additives such as a colorant may be included. In this case, it is preferable that the monofunctional radical polymerizable monomer is the main component among the components contained in the in-situ polymerization type thermoplastic resin composition other than the solvent. The main component means that the content of the monofunctional radical polymerizable monomer is 50 to 100 mass %. The content is preferably 60 mass % or more, more preferably 80 mass % or more.

Examples of the in situ polymerization type thermoplastic resin composition include the following in situ polymerization type thermoplastic resin compositions (A) to (D).
In-situ polymerization type thermoplastic resin composition (A): A composition containing at least one of the above (a) to (g).
In-situ polymerization type thermoplastic resin composition (B): A composition containing at least one of the above (a) to (g) and maleic anhydride-modified polypropylene or modified polyphenylene ether.
In-situ polymerization type thermoplastic resin composition (C): A composition containing at least one of the (a) to (g) and a thermoplastic resin different from the resin constituting the first resin.
In-situ polymerization type thermoplastic resin composition (D): A composition containing at least one of the above (a) to (g), maleic anhydride modified polypropylene or modified polyphenylene ether, and a thermoplastic resin different from the resin constituting the first resin.

The maleic anhydride-modified polypropylene is a polypropylene graft-modified with maleic anhydride. Specific commercial products include "Kayabrid 002PP, 002PP-NW, 003PP, 003PP-NW" (all manufactured by Kayaku Akzo Co., Ltd.), "Modic (registered trademark)" (manufactured by Mitsubishi Chemical Corporation), and the like.
In addition, "SCONA TPPP2112GA, TPPP8112GA, TPPP9212GA" (all manufactured by BYK) may be used in combination as a polypropylene additive functionalized with maleic anhydride.
In particular, when polypropylene (PP) is used as the resin, the in situ polymerization type composition preferably contains maleic anhydride modified polyolefin.

As the modified polyphenylene ether, known ones can be used.
The modified polyphenylene ether is a blend of polyphenylene ether with polystyrene, polyamide, polyphenylene sulfide, polypropylene, etc. Specific commercial products include "NORYL series (PPS/PS) 731, 7310, 731F, 7310F" (all manufactured by SABIC Japan LLC), "ZYLON series (PPE/PS, PP/PPE, PA/PPE, PPS/PPE, PPA/PPE)" (all manufactured by Asahi Kasei Chemicals Corporation), "EPIACE series (PPE/PS, PPE/PA)" (manufactured by Mitsubishi Engineering Plastics Corporation), and "LEMALLOY series (PPE/PS, PPE/PA)" (all manufactured by Mitsubishi Engineering Plastics Corporation).

The total amount of the (a) to (g) in the in situ polymerization type composition (B) is preferably 5 to 100 parts by mass, more preferably 5 to 60 parts by mass, and even more preferably 20 to 40 parts by mass, based on 100 parts by mass of the maleic anhydride-modified polypropylene or the modified polyphenylene ether.
The total amount of the (a) to (g) in the in situ polymerization type composition (D) is preferably 5 to 100 parts by mass, more preferably 5 to 60 parts by mass, and even more preferably 20 to 40 parts by mass, based on 100 parts by mass of the maleic anhydride-modified polypropylene or the modified polyphenylene ether.

The in-situ polymerization type thermoplastic resin composition may contain, in addition to the components (a) to (g), a rubber component such as a carboxy-terminated butadiene nitrile rubber, or a polymer capable of imparting toughness, such as an aromatic polyether ketone, a silicone elastomer, or an acrylic resin.
An example of the aromatic polyether ketone is polyether ether ketone (PEEK).
Examples of silicone elastomers include "DOWSIL EP-2600" (manufactured by The Dow Chemical Company) and "DOWSIL EP-2601" (manufactured by The Dow Chemical Company).
Examples of acrylic resins include methyl methacrylate-butadiene styrene-styrene copolymers (MBS) such as "BTA-730" (manufactured by The Dow Chemical Company), polymethyl methacrylate (PMMA), and the like.
The in-situ polymerization type composition contains a rubber component and a polymer capable of imparting toughness, thereby improving the impact resistance of the bonded body.

As the in-situ polymerization type thermoplastic resin composition, although it depends on the type of resin, it is preferable to select a composition containing a resin similar to the resin constituting the first resin. For example, when the first resin is a polyolefin, stronger welding can be achieved by using an in-situ polymerization type thermoplastic resin composition containing maleic anhydride modified polyolefin. Also, when the first resin is a modified polyphenylene ether, stronger welding can be achieved by using an in-situ polymerization type thermoplastic resin composition containing modified polyphenylene ether.
In addition, it is preferable to select a composition containing a resin similar to the resin constituting the second resin as the in-situ polymerization type thermoplastic resin composition. Here, the similar resin refers to a resin having a similar SP value (solubility parameter). However, it is preferable that the in-situ polymerization type thermoplastic resin composition constituting the primer layer (A) and the in-situ polymerization type thermoplastic resin composition constituting the primer layer (B) have similar components, and more preferably, they have the same components.

The in situ polymerization type thermoplastic resin composition may contain any additives such as a solvent, a colorant, an antioxidant, etc. If the in situ polymerization type thermoplastic resin composition is liquid, a solvent may not be used.
Examples of the solvent include methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, toluene, xylene, tetrahydrofuran, and water.

<Thermoplastic resin>
In this embodiment, the thermoplastic resin used to form the primer layer (A), the primer layer (B), and the primer layer (C) is not particularly limited, and may be the same as the thermoplastic resin used as the first resin and the second resin described above. The thermoplastic resin used to form the primer layer (A), the primer layer (B), and the primer layer (C) may be the same type of thermoplastic resin as the first resin and the second resin, or may be a different type of thermoplastic resin.

In the method for producing a bonded body in this embodiment, a primer layer different from the primer layer (C) may be formed on a material such as metal, glass, ceramics, etc. The other primer layer may be a polymer layer obtained by polymerizing the in-situ polymerization type thermoplastic resin composition, a primer layer made of the thermoplastic resin, or a primer layer made of a different component.
Since the primer layer (C) is welded to the primer layer (A) by ultrasonic welding, at least the outermost surface of materials such as metals, glass, and ceramics is the primer layer (C). From the viewpoint of obtaining sufficient bonding strength, it is preferable that the primer layer (C) contacts the material, that is, when the material forms the other primer layer, at least two layers, the bonding surface in contact with the material and the outermost surface, are the primer layer (C).

From the viewpoint of improving the strength and heat resistance of the primer layer, the material may be provided with a thermosetting resin layer formed from a composition containing a thermosetting resin as the other primer layer.
The composition containing the thermosetting resin may contain a solvent and, if necessary, an additive such as a colorant, in order to sufficiently advance the curing reaction of the thermosetting resin and form a desired thermosetting resin layer. In this case, it is preferable that the thermosetting resin is the main component among the components contained in the composition other than the solvent. The main component means that the content of the thermosetting resin is 40 to 100 mass%. The content is preferably 60 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more.

Examples of the thermosetting resin include urethane resin, epoxy resin, vinyl ester resin, and unsaturated polyester resin.
The thermosetting resin layer may be formed of one of these resins alone or a mixture of two or more of them. Alternatively, the thermosetting resin layer may be composed of multiple layers, each layer being formed of a composition containing a different type of thermosetting resin.

The coating method for forming a thermosetting resin layer using a composition containing the thermosetting resin monomer is not particularly limited, but examples include spray coating and dipping.

The thermosetting resin in this embodiment broadly means a resin that cures by crosslinking, and is not limited to the heat-curing type, but also includes the room temperature curing type and the light-curing type. The light-curing type can be cured in a short time by irradiation with visible light or ultraviolet light. The light-curing type may be used in combination with the heat-curing type and/or the room temperature curing type. Examples of the light-curing type include vinyl ester resins such as "Lipoxy (registered trademark) LC-720, LC-760" (both manufactured by Showa Denko KK).

(urethane resin)
The urethane resin is usually a resin obtained by reacting an isocyanato group of an isocyanate compound with a hydroxyl group of a polyol compound, and is preferably a urethane resin that corresponds to the definition of "a coating material containing a polyisocyanate with a vehicle non-volatile component of 10 wt % or more" in ASTM D16. The urethane resin may be of one-component type or two-component type.

Examples of one-component urethane resins include oil-modified types (cured by oxidative polymerization of unsaturated fatty acid groups), moisture-cured types (cured by reaction of isocyanato groups with water in the air), block types (cured by reaction of hydroxyl groups with isocyanato groups regenerated by dissociation of the blocking agent by heating), and lacquer types (cured by evaporation of the solvent and drying). Among these, moisture-cured one-component urethane resins are preferably used from the viewpoint of ease of handling. A specific example is "UM-50P" (manufactured by Showa Denko KK).

Examples of two-component urethane resins include catalyst-curing types (which cure when isocyanato groups react with water in the air in the presence of a catalyst) and polyol-curing types (which cure when isocyanato groups react with hydroxyl groups of a polyol compound).

Examples of the polyol compound in the polyol curing type include polyester polyol, polyether polyol, and phenol resin.
Examples of the isocyanate compound having an isocyanato group in the polyol curing type include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), tetramethylene diisocyanate, and dimer acid diisocyanate; aromatic isocyanates such as 2,4- or 2,6-tolylene diisocyanate (TDI) or mixtures thereof, p-phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate (MDI) and polymeric MDI, which is a polynuclear mixture thereof; and alicyclic isocyanates such as isophorone diisocyanate (IPDI).
The compounding ratio of the polyol compound to the isocyanate compound in the polyol-curing type two-component urethane resin is preferably such that the molar equivalent ratio of hydroxyl group/isocyanato group is in the range of 0.7 to 1.5.

Examples of urethanization catalysts used in the two-component urethane resin include amine-based catalysts such as triethylenediamine, tetramethylguanidine, N,N,N',N'-tetramethylhexane-1,6-diamine, dimethyletheramine, N,N,N',N'',N''-pentamethyldipropylene-triamine, N-methylmorpholine, bis(2-dimethylaminoethyl)ether, and dimethylaminoethoxyethanol-triethylamine; and organotin-based catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin thiocarboxylate, and dibutyltin dimaleate.
In the polyol curing type, it is generally preferable to mix 0.01 to 10 parts by mass of the urethane catalyst with respect to 100 parts by mass of the polyol compound.

(Epoxy resin)
The epoxy resin is a resin having at least two epoxy groups in one molecule.
Examples of the prepolymer of the epoxy resin before curing include ether-based bisphenol-type epoxy resins, novolac-type epoxy resins, polyphenol-type epoxy resins, aliphatic-type epoxy resins, ester-based aromatic epoxy resins, cyclic aliphatic epoxy resins, ether-ester-based epoxy resins, etc., and among these, bisphenol A-type epoxy resins are preferably used. Among these, one type may be used alone, or two or more types may be used in combination.
Specific examples of bisphenol A type epoxy resins include "jER (registered trademark) 828 and 1001" (both manufactured by Mitsubishi Chemical Corporation).
Specific examples of novolac type epoxy resins include "D.E.N. (registered trademark) 438 (registered trademark)" (manufactured by The Dow Chemical Company).

Examples of the curing agent used for the epoxy resin include known curing agents such as aliphatic amines, aromatic amines, acid anhydrides, phenolic resins, thiols, imidazoles, cationic catalysts, etc. The curing agent, when used in combination with a long-chain aliphatic amine and/or thiols, can provide the effect of providing a large elongation and excellent impact resistance.
Specific examples of the thiols include the same compounds as those exemplified as the thiol compounds for forming the functional group-containing layer described below. Among these, pentaerythritol tetrakis(3-mercaptobutyrate) (e.g., Karenz MT (registered trademark) PE1 (manufactured by Showa Denko K.K.)) is preferred from the viewpoints of elongation and impact resistance.

(Vinyl ester resin)
The vinyl ester resin is a compound obtained by dissolving a vinyl ester compound in a polymerizable monomer (such as styrene). Although it is also called an epoxy (meth)acrylate resin, the vinyl ester resin also includes a urethane (meth)acrylate resin.
As the vinyl ester resin, for example, those described in "Polyester Resin Handbook" (published by Nikkan Kogyo Shimbun, Ltd. in 1988) and "Paint Terminology Dictionary" (published by Shikizai Kyokai, 1993) can be used. Specific examples include "Lipoxy (registered trademark) R-802, R-804, R-806" (all manufactured by Showa Denko K.K.).

The urethane (meth)acrylate resin may be, for example, a radically polymerizable unsaturated group-containing oligomer obtained by reacting an isocyanate compound with a polyol compound, followed by reaction with a hydroxyl group-containing (meth)acrylic monomer (and, if necessary, a hydroxyl group-containing allyl ether monomer). Specific examples include "Lipoxy (registered trademark) R-6545" (manufactured by Showa Denko KK).

The vinyl ester resin can be cured by radical polymerization through heating in the presence of a catalyst such as an organic peroxide.
The organic peroxide is not particularly limited, but examples thereof include ketone peroxides, peroxyketals, hydroperoxides, diallyl peroxides, diacyl peroxides, peroxy esters, peroxydicarbonates, etc. By combining these with a cobalt metal salt or the like, curing at room temperature is also possible.
The cobalt metal salt is not particularly limited, but examples thereof include cobalt naphthenate, cobalt octylate, cobalt hydroxide, etc. Among these, cobalt naphthenate and/or cobalt octylate are preferred.

(Unsaturated polyester resin)
The unsaturated polyester resin is prepared by dissolving a condensation product (unsaturated polyester) obtained by an esterification reaction between a polyol compound and an unsaturated polybasic acid (and, if necessary, a saturated polybasic acid) in a polymerizable monomer (e.g., styrene, etc.).
As the unsaturated polyester resin, those described in "Polyester Resin Handbook" (published by Nikkan Kogyo Shimbun, 1988) and "Paint Terminology Dictionary" (published by Shikizai Kyokai, 1993) can be used. Specific examples include "Rigolac (registered trademark)" (manufactured by Showa Denko K.K.).

The unsaturated polyester resin can be cured by radical polymerization through heating in the presence of a catalyst similar to that used for the vinyl ester resin.

The total thickness of the primer layers (A) to (C) (the thickness after polymerization of the in-situ polymerized thermoplastic resin composition and before ultrasonic welding) and the thickness of the other primer layer different from the primer layers (A) to (C) (the thickness after polymerization of the in-situ polymerized thermoplastic resin composition and before ultrasonic welding) depends on the materials of the first resin, the second resin, the metal, the glass, and the ceramics, and the contact area of the joint, but is preferably 1 μm to 500 μm, more preferably 3 μm to 100 μm, and even more preferably 5 μm to 70 μm, from the viewpoint of obtaining sufficient joint strength.

<Ultrasonic welding>
As mentioned above, ultrasonic welding refers to heating the joining surfaces of the same or different materials using ultrasonic vibrations to a temperature above the softening point or melting point of the components present on at least one of the joining surfaces, and joining the same or different materials by entanglement or crystallization due to molecular diffusion upon contact pressure and cooling.
In one aspect of this embodiment, ultrasonic welding is performed by arranging the first resin and the second resin so as to be joined via the primer layer (A).
In another aspect of this embodiment, ultrasonic welding is performed by arranging the first resin and the second resin so as to be joined via the primer layers (A) and (B).
In yet another aspect of this embodiment, ultrasonic welding is performed in such a manner that a first resin and at least one material selected from metal, glass, and ceramics are joined via primer layers (A) and (C).

The pressure (holding pressure) applied to the first resin, second resin, metal, glass and ceramics during ultrasonic welding is preferably 0.15 to 0.6 MPa/sec, more preferably 0.2 to 0.5 MPa/sec, and even more preferably 0.25 to 0.5 MPa/sec, from the viewpoint of obtaining sufficient joint strength and suppressing deformation of the first resin and second resin.

[Conjugate]
The bonded body in one aspect of this embodiment is a bonded body obtained by a method for producing a bonded body, the method including the steps of: heating at least one selected from a thermoplastic resin composition and a thermoplastic resin on a surface of the first resin to a temperature that is at least 5° C. lower than the softening point of the first resin or at least 5° C. lower than the melting point of the first resin to form a primer layer (A); and welding the primer layer (A) to the second resin by ultrasonic welding.
The bonded body in one aspect of the present embodiment may be a bonded body obtained by a manufacturing method for a bonded body, the manufacturing method including: a step of forming the primer layer (A); and a step of heating at least one selected from a thermoplastic resin composition and a thermoplastic resin on a surface of the second resin to a temperature that is at least 5° C. lower than the softening point of the second resin material or at least 5° C. lower than the melting point of the second resin material to form a primer layer (B), the welding step including welding the primer layer (A) and the primer layer (B) by ultrasonic welding.
The bonded body in another aspect of this embodiment is a bonded body obtained by bonding a first resin to at least one material selected from metal, glass, and ceramics, and is obtained by a method for producing a bonded body, the method including: heating at least one material selected from a thermoplastic resin composition and a thermoplastic resin on a surface of the first resin to a temperature that is at least 5° C. lower than the softening point of the first resin or at least 5° C. lower than the melting point of the first resin to form a primer layer (A); forming a primer layer (C) on the material using at least one material selected from a thermoplastic resin composition and a thermoplastic resin; and welding the primer layer (A) and the primer layer (C) by ultrasonic welding.

Next, specific examples of the present invention will be described, but the present invention is not limited to these examples.

[First Resin and Second Resin Test Pieces]
In the following Examples and Comparative Examples, the details of each resin used as the first resin and the second resin for producing each resin test piece are shown below. The resin test pieces were injection molded using an injection molding machine "SE100V" (manufactured by Sumitomo Heavy Industries, Ltd.) under the conditions shown in Table 2 below, and had dimensions of 10 mm x 45 mm x 3 mm.

PA6: Polyamide 6, containing 30% glass fiber by mass, melting point 225°C, "Novamid (registered trademark)" (manufactured by DSM)
PA66: Polyamide 66, containing 30% by mass of glass fiber, melting point 265°C, "Novamid (registered trademark)" (manufactured by DSM)
PPS: polyphenylene sulfide, containing 40% glass fiber by mass, melting point 278°C, "FZ-2140" (manufactured by DIC Corporation)
PEI: Polyetherimide, softening point 211°C, "Ultem (registered trademark) 1040" (manufactured by SABIC)
PC: Polycarbonate, softening point 144°C, "Makrolon (registered trademark) 2405" (manufactured by SABIC)
PBT: Polybutylene terephthalate, containing 30% glass fiber by mass, melting point 224°C, "Barox 507" (manufactured by SABIC)
PP: Polypropylene, containing 30% by mass of talc, melting point 160°C, "TRC104N" (manufactured by SunAllomer Co., Ltd.)

[Metal, glass and ceramic test pieces]
In the following Examples and Comparative Examples, details of the metals (aluminum, steel and copper), glasses and ceramics used in the manufacture of each test piece are given below.
Aluminum: A6063, 18mm x 45mm, thickness 1.5mm
Steel: Steel plate, SPHC (JIS G 3131:2018), thickness 1.6 mm
Copper: C1100P (JIS H 3100:2018), thickness 1.5 mm
Glass: Chemically strengthened glass, "Dinorex (registered trademark) T2X-1", manufactured by Nippon Electric Glass Co., Ltd., 18 mm x 45 mm, thickness 1.5 mm
Ceramics: Alumina, thick film substrate, Kyocera Corporation, 18 mm x 45 mm, thickness 1 mm

[Surface treatment]
<First Resin and Second Resin>
As a surface treatment of the resins used in the manufacture of the test pieces of the first and second resins, a UV cleaning and modification device "PL16-110" (manufactured by Sen Engineering Co., Ltd., lamp used: SUV110GS-36) was used at an irradiation distance of 50 mm and an irradiation time of 1 minute. UV ozone treatment was performed.

<Aluminum>
The aluminum used to manufacture the test pieces was surface treated as follows.
An aluminum test piece was immersed in a 5% by mass aqueous sodium hydroxide solution at room temperature for 1.5 minutes, neutralized with a 5% by mass aqueous nitric acid solution, washed with water, and dried, thereby carrying out an etching treatment.
Next, the aluminum test piece that had been subjected to the etching treatment was immersed for 20 minutes in a silane coupling agent-containing solution at 70°C in which 2 g of 3-aminopropyltrimethoxysilane (silane coupling agent "KBM-903" (manufactured by Shin-Etsu Silicones Co., Ltd.)) was dissolved in 1000 g of industrial ethanol, and the metal test piece was then taken out and dried to perform a functional group imparting treatment, thereby obtaining an aluminum test piece imparted with functional groups.

<Steel, copper and ceramics>
The steel, copper and ceramics used to manufacture the test pieces were surface treated as follows.
Using an atmospheric pressure plasma treatment device "Openair-Plasma (registered trademark) Generator FG5001" (manufactured by Plasmatreat), plasma treatment was performed on the surfaces of each of the steel, copper, and ceramic test pieces under conditions of an irradiation distance of 15 mm and a feed rate of 5 m/min.
Next, the steel, copper and ceramic test pieces that had been subjected to the plasma treatment were subjected to a functional group imparting treatment in the same manner as the aluminum test pieces, to obtain steel, copper and ceramic test pieces to which functional groups had been imparted.

[Preparation of in situ polymerized thermoplastic resin composition]
<In-situ polymerizable thermoplastic resin composition (1)>
90.1 g of a bifunctional epoxy resin “jER (registered trademark) 1007” (manufactured by Mitsubishi Chemical Corporation), 5.2 g of bisphenol S, 4.6 g of a carboxy-terminated butadiene nitrile rubber “Hiker (registered trademark) CTBN 1300×13” (manufactured by Lubrizol Corporation), and 0.4 g of triphenylphosphine were dissolved in 186 g of methyl ethyl ketone to prepare an in-situ polymerization type thermoplastic resin composition (1).

<In-situ polymerizable thermoplastic resin composition (2)>
5 g of maleic anhydride-modified polypropylene "Modic (registered trademark) ER321P" (manufactured by Mitsubishi Chemical Corporation) and 95 g of xylene were mixed and heated to 125°C with stirring to dissolve the maleic anhydride-modified polypropylene. 1.01 g of bifunctional epoxy resin "jER (registered trademark) 1001" (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, molecular weight approximately 900), 0.24 g of bisphenol A, and 0.006 g of triphenylphosphine were added and dissolved, and then the mixture was heated at room temperature. The mixture was cooled to a temperature of 150° C. to obtain an in-situ polymerization type thermoplastic resin composition (2).

Example 1-1
(Formation of primer layer)
On the surface-treated surface of the resin test piece, the resin material of which was PA6, the in-situ polymerization type thermoplastic resin composition (1) was applied by spraying so that the primer layer thickness after drying was 32 μm. After leaving it in the air at room temperature for 30 minutes to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then heated for 10 minutes in a furnace at a temperature of 224 ° C., which is a temperature 5 ° C. lower than the melting point of PA6 (225 ° C.), and then cooled to room temperature to obtain a primer-attached test piece P1-1 having a primer layer on one surface.
In addition, the in-situ polymerization type thermoplastic resin composition (1) was sprayed onto the surface-treated surface of the resin test piece, the resin material of which was PBT, so that the primer layer thickness after drying was 31 μm. After leaving it in the air at room temperature for 30 minutes to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then heated for 10 minutes in a furnace at a temperature of 223 ° C., which is a temperature 5 ° C. lower than the melting point of PBT (224 ° C.), and then cooled to room temperature to obtain a primer-attached test piece P1-11 having a primer layer on one surface.

(Welding)
The primer-attached test piece P1-1 and the primer-attached test piece P1-11 were overlapped so that the joint surface between the surfaces of both primer layers was 5 mm × 10 mm, and ultrasonic welding was performed under pressure (set pressure: 0.24 MPa) using an ultrasonic welding machine "SONOPET-JII2410" (manufactured by Seidensha Denshi Kogyo Co., Ltd.) under the following conditions to obtain a resin-resin joint. Here, the joint surface means the part where the resin test pieces were overlapped.
Amplitude: 24 μm
・Transmission frequency: 19.15kHz
Transmission time: 0.264 seconds Hold time: 1.0 seconds Peak power: 387W

(tensile shear strength)
The resin-resin bonded body was allowed to stand at room temperature for one day, and then subjected to a tensile shear strength test in accordance with ISO19095 1-4 using a tensile tester (Universal testing machine autograph "AG-IS" (manufactured by Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm/min, temperature 23°C, 50% RH) to measure the tensile shear strength. The measurement results are shown in Table 3.

Example 1-2
(Formation of primer layer)
On the surface-treated surface of the resin test piece, the resin material of which was PA6, the in-situ polymerization type thermoplastic resin composition (1) was applied by spraying so that the primer layer thickness after drying was 54 μm. After leaving it in the air at room temperature for 30 minutes to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then heated for 10 minutes in a furnace at a temperature of 224 ° C., which is a temperature 5 ° C. lower than the melting point of PA6 (225 ° C.), and then cooled to room temperature to obtain a primer-attached test piece P1-2 having a primer layer on one surface.

(Welding)
The primer-attached test piece P1-2 and a test piece p1-1 (without a primer layer) which had been subjected to only a surface treatment and whose resin material was PPS were overlapped so that the joint surface between the surface of the primer layer of the test piece P1-2 and the surface-treated surface of the test piece p1-1 was 5 mm × 10 mm, and they were ultrasonically welded under pressure under the same conditions as in Example 1-1, to obtain a resin-resin joint.

(tensile shear strength)
The tensile shear test was carried out in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 3.

[Examples 1-3, 1-5, 1-7, 1-9, 1-11, and 1-13]
A resin-resin bonded body was obtained in the same manner as in Example 1-1, except that a resin having the material shown in Table 3 was used, and the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)), the heating conditions for forming the primer layer (heating temperature and heating time), and the thickness of the primer layer were shown in Table 3. Furthermore, a tensile shear test was performed on the bonded body in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 3.

[Examples 1-4, 1-6, 1-8, 1-10, 1-12, and 1-14]
A resin-resin bonded body was obtained in the same manner as in Example 1-2, except that a resin having the material shown in Table 3 was used, the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)), the heating conditions for heating the primer layer (heating temperature and heating time), and the thickness of the primer layer were shown in Table 3. Furthermore, a tensile shear test was performed on the bonded body in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 3.

Comparative Example 1-1
(Formation of primer layer)
On the surface-treated surface of a resin test piece whose resin material was PA6, an in-situ polymerization type thermoplastic resin composition (1) was applied by a spray method so that the primer layer thickness after drying was 32 μm. After leaving it at room temperature for 30 minutes in the air to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then cooled to room temperature without heating at a temperature 5 ° C. lower than the melting point of PA6 (225 ° C.) or higher, to obtain a primer-attached test piece Q1-1 having a primer layer on one surface.
In addition, the in-situ polymerization type thermoplastic resin composition (1) was sprayed onto the surface-treated surface of the resin test piece, the resin material of which was PBT, so that the primer layer thickness after drying was 31 μm. After leaving it in the air at room temperature for 30 minutes to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then cooled to room temperature without heating at a temperature 5 ° C. lower than the melting point of PBT (224 ° C.) or higher, to obtain a primer-attached test piece Q1-9 having a primer layer on one surface.

(Welding)
Resin-resin joints were obtained by ultrasonic welding under pressure under the same conditions as in Example 1-1, except that test pieces Q1-1 and Q1-9 were used instead of test pieces P1-1 and P1-11.

(tensile shear strength)
The tensile shear test was carried out in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 4.

Comparative Example 1-2
(Formation of primer layer)
On the surface-treated surface of the resin test piece whose resin material was PA6, the in-situ polymerization type thermoplastic resin composition (1) was spray-coated so that the primer layer thickness after drying was 54 μm. After leaving it at room temperature for 30 minutes in the air to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was heated for 30 minutes in a furnace at a temperature of 150 ° C., and then cooled to room temperature without heating at a temperature 5 ° C. lower than the melting point of PA6 (225 ° C.) or higher, to obtain a primer-coated test piece Q1-2 having a primer layer on one surface.

(Welding)
The primer-attached test piece Q1-2 and a test piece p1-1 (without a primer layer) which had been subjected to only a surface treatment and whose resin material was PPS were overlapped so that the joint surface between the surface of the primer layer of the test piece Q1-2 and the surface-treated surface of the test piece p1-1 was 5 mm × 10 mm, and they were ultrasonically welded under pressure under the same conditions as in Example 1-1, to obtain a resin-resin joint.

(tensile shear strength)
The tensile shear test was carried out in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 4.

[Comparative Examples 1-3, 1-5, 1-7, 1-9, and 1-11]
In Comparative Example 1-1, a resin-resin bonded body was obtained in the same manner as in Example 1-1, except that a resin having the material shown in Table 4 was used, and the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)), the heating conditions for forming the primer layer (heating temperature and heating time), and the thickness of the primer layer were shown in Table 4. Furthermore, a tensile shear test was performed on the bonded body in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 4.

[Comparative Examples 1-4, 1-6, 1-8, 1-10, and 1-12]
In Comparative Example 1-2, a resin-resin bonded body was obtained in the same manner as in Example 1-1, except that a resin having the material shown in Table 4 was used, the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)), the heating conditions for heating the primer layer (heating temperature and heating time), and the thickness of the primer layer were shown in Table 4. Furthermore, a tensile shear test was performed on the bonded body in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 4.

Example 2-1
(Formation of primer layer)
A primer-coated test piece P1-1 having a primer layer and made of PA6 resin was obtained in the same manner as in Example 1-1.
In addition, the in-situ polymerization type thermoplastic resin composition (1) was sprayed onto the surface-treated surface of the aluminum test piece so that the primer layer thickness after drying was 31 μm. After leaving it in the air at room temperature for 30 minutes to volatilize the solvent, the in-situ polymerization type thermoplastic resin composition (1) was polymerized for 60 minutes in a furnace at a temperature of 150 ° C., and then cooled to room temperature to obtain a primer-attached test piece P2-1 having a primer layer on one surface.

(Welding)
The primer-attached test piece P1-1 and the primer-attached test piece P2-1 were overlapped so that the joint surface between the surfaces of both primer layers was 5 mm × 10 mm, and ultrasonic welding was performed under pressure (set pressure: 0.24 MPa) using an ultrasonic welding machine "SONOPET-JG1530S" (manufactured by Seidensha Denshi Kogyo Co., Ltd.) under the same conditions as in Example 1-1 to obtain a resin-metal joint. Here, the joint surface means the portion where the resin test piece and the metal test piece were overlapped.

(tensile shear strength)
The tensile shear test was carried out in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 5.

[Examples 2-2 to 2-10]
In Example 2-1, a resin-metal bonded body, a resin-glass bonded body, and a resin-ceramic bonded body were obtained in the same manner as in Example 2-1, except that the resins and materials shown in Table 4 were used, the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)), the heating conditions for forming the primer layer (heating temperature and heating time), and the thickness of the primer layer were shown in Table 4. Furthermore, a tensile shear test was performed on the bonded bodies in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 5.

[Comparative Examples 2-1 to 2-10]
In Example 2-1, resins and materials of the materials shown in Table 6 were used, and the in situ polymerization type thermoplastic resin composition used to form the primer layer (in situ polymerization type thermoplastic resin composition (1) or in situ polymerization type thermoplastic resin composition (2)) used in the formation of the primer layer shown in Table 6, heating conditions for forming the primer layer (heating temperature and heating time), and thickness of the primer layer were set as shown in Table 6. When the in situ polymerization type thermoplastic resin composition was heated on the surface of the resin test piece, the resin was not heated at a temperature higher than the softening point and melting point of the resin. In addition, a tensile shear test was performed on the bonded body in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 6.

Example 3-1
(Formation of primer layer)
A nylon 6 film "Santonil SNR" (manufactured by Mitsubishi Chemical Corporation, thickness 15 μm) measuring 10 mm x 5 mm was placed on the edge of the surface-treated surface of a resin test piece whose resin material was PPS, and the nylon 6 film was bonded by heating for 5 minutes in an oven at a temperature of 278°C, and then allowed to cool to room temperature to obtain a primer-attached test piece P3-1 having a primer layer on one surface.

(Welding)
The primer-attached test piece P3-1 and the test piece p3-1 (without a primer layer) which had been subjected to only a surface treatment and whose resin material was PA6 were overlapped so that the joint surface between the surface of the primer layer of the test piece P3-1 and the surface-treated surface of the test piece p1-1 was 5 mm x 10 mm, and ultrasonic welding was performed under pressure under the same conditions as in Example 1-1 using an ultrasonic welding machine "SONOPET-JG1530S" (manufactured by Seidensha Denshi Kogyo Co., Ltd.), to obtain a resin-resin joint. Here, the joint surface means the portion where the resin test piece and the resin test piece were overlapped.

(tensile shear strength)
The resin-resin bonded body was immersed in 60° C. hot water for 24 hours, and then subjected to a tensile shear test in the same manner as in Example 1-1 to measure the tensile shear strength. The measurement results are shown in Table 7.

Comparative Example 3-1
A nylon 6 film "Santonil SNR" (manufactured by Mitsubishi Chemical Corporation, thickness 15 μm) measuring 10 mm × 5 mm was sandwiched between an end of the surface-treated surface of resin test piece Q2-1, whose resin material was PPS, and an end of the surface-treated surface of a resin test piece Q2-1 different from the resin test piece Q2-1, and the two were overlapped so that the bonding surfaces were 5 mm × 10 mm, and ultrasonic welding was performed under the same conditions as in Example 3-1, to obtain a resin-resin bonded body that was ultrasonically welded without forming a primer layer by heating to the melting point of PPS or higher. Here, the bonding surface means the part where the resin test piece and the resin test piece were overlapped.
When the resin-resin bonded article was immersed in 60° C. warm water for 24 hours, the bonded portion peeled off, so a tensile shear test was not performed.

As can be seen from Tables 3 to 7 above, the manufacturing method of the bonded body of the present invention can bond resin to resin, and resin to at least one material selected from metal, glass, and ceramics, with sufficient bonding strength, and can also improve the bonding strength.

The uses of the joint produced using the manufacturing method of the present invention are not particularly limited, but can be applied to, for example, door side panels, bonnet roofs, tailgates, steering hangers, A-pillars, B-pillars, C-pillars, D-pillars, crash boxes, power control unit (PCU) housings, electric compressor components (inner wall parts, intake ports, exhaust control valve (ECV) insertion parts, mount boss parts, etc.), lithium ion battery (LIB) spacers, battery cases, LED headlamps and other automotive parts, as well as smartphones, notebook computers, tablet computers, smartwatches, large liquid crystal televisions (LCD-TVs), outdoor LED lighting structures, etc.

Claims (12)

A method for producing a bonded body obtained by bonding a first resin and a second resin, comprising the steps of:
forming a primer layer (A) on the surface of the first resin by heating an in situ polymerization type thermoplastic resin composition to a temperature 5° C. lower than the softening point of the first resin or a temperature 5° C. lower than the melting point of the first resin;
a step of welding the primer layer (A) to the second resin by ultrasonic welding. The method includes a step of forming a primer layer (B) by heating an in situ polymerization type thermoplastic resin composition on a surface of the second resin to a temperature 5° C. lower than the softening point of the second resin or a temperature 5° C. lower than the melting point of the second resin, and polymerizing the composition;
The method for producing a joint body according to claim 1 , wherein the welding step includes welding the primer layer (A) and the primer layer (B) by ultrasonic welding. A method for producing a bonded body obtained by bonding a first resin to at least one material selected from metal, glass, and ceramics, comprising the steps of:
forming a primer layer (A) on the surface of the first resin by heating an in situ polymerization type thermoplastic resin composition to a temperature 5° C. lower than the softening point of the first resin or a temperature 5° C. lower than the melting point of the first resin;
forming a primer layer (C) on the material by polymerizing an in situ polymerized thermoplastic resin composition ;
A method for producing a bonded body, comprising: a step of welding the primer layer (A) and the primer layer (C) by ultrasonic welding. The method for producing a joint body according to any one of claims 1 to 3 , wherein a joint surface of the first resin on the primer layer (A) side is subjected to one or more surface treatments selected from a degreasing treatment, a sanding treatment, a plasma treatment, a corona discharge treatment, and a UV ozone treatment. The method for producing the joint body according to claim 1, wherein the joint surface of the second resin on the primer layer (A) side is subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment, and UV ozone treatment. The method for producing a joint body according to claim 2, wherein the joint surface of the second resin on the primer layer (B) side is subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment, and UV ozone treatment. The method for producing the bonded body according to claim 3, wherein the bonding surface of the material on the primer layer (C) side is subjected to one or more surface treatments selected from degreasing treatment, sanding treatment, plasma treatment, corona discharge treatment, UV ozone treatment, and functional group imparting treatment. The method for producing a joined body according to any one of claims 1 to 7 , wherein the in situ polymerization type thermoplastic resin composition contains at least one selected from the following (a) to (g):
(a) A combination of a bifunctional isocyanate compound and a diol (b) A combination of a bifunctional isocyanate compound and a bifunctional amino compound (c) A combination of a bifunctional isocyanate compound and a bifunctional thiol compound (d) A combination of a bifunctional epoxy compound and a diol (e) A combination of a bifunctional epoxy compound and a bifunctional carboxy compound (f) A combination of a bifunctional epoxy compound and a bifunctional thiol compound (g) A combination of a radical polymerizable monofunctional monomer The method for producing a joined body according to claim 8 , wherein the in-situ polymerization type thermoplastic resin composition further contains a maleic anhydride modified polyolefin. The method for producing a joined body according to claim 3 or 7, further comprising applying a solution containing at least one selected from the following (c1) to (c7) to the material to form a functional group-imparting treated surface, and then forming a primer layer (C ) on the functional group-imparting treated surface:
(c1) a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a mercapto group; (c2) a silane coupling agent having an amino group, and at least one compound selected from the group consisting of an epoxy compound and a thiol compound; (c3) a silane coupling agent having a mercapto group, and at least one compound selected from the group consisting of an epoxy compound, an amino compound, an isocyanate compound, a compound having a (meth)acryloyl group and an epoxy group, and a compound having a (meth)acryloyl group and an amino group; (c4) a silane coupling agent having a (meth)acryloyl group, and a thiol compound; (c5) a silane coupling agent having an epoxy group, and at least one compound selected from the group consisting of an amino compound, a thiol compound, and a compound having an amino group and a (meth)acryloyl group; (c6) an isocyanate compound; (c7) a thiol compound. 4. The method for producing a joined body according to any one of claims 1 to 3, wherein the step of forming the primer layer (A) comprises heating an in situ polymerization type thermoplastic resin composition on a surface of the first resin to a temperature not higher than 15°C higher than the softening point of the first resin or not higher than 5°C higher than the melting point of the first resin to form the primer layer (A). 3. The method for producing a joined body according to claim 2, wherein the step of forming the primer layer (B) comprises heating an in situ polymerization type thermoplastic resin composition on a surface of the second resin to a temperature not higher than 15° C. higher than the softening point of the second resin or not higher than 5° C. higher than the melting point of the second resin to form the primer layer (B).