JP7298068B2 - Adhesion method of rubber members - Google Patents

Description

The present invention relates to a method for bonding rubber members. In particular, the present invention relates to a method of adhering rubber members having adhesion regions with excellent adhesiveness.

Conventionally, a solution containing a reducing agent is applied to the surface of a member to be joined in advance as a primer, and a composition containing (1) a polymerizable vinyl monomer, (2) a polymerization initiator, and (3) butyl rubber is applied to the surface of the member to be joined. A method of joining members together is known (see, for example, Patent Document 1). According to the method described in Patent Document 1, when the members to be joined are joined with a butyl rubber-based material, good adhesiveness can be exhibited, and joint strength can be developed quickly after joining.

JP 2007-197638 A

However, in the method described in Patent Document 1, since a primer containing a reducing agent is used, adhesive strength may not be sufficient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for bonding rubber members having a bonding region with excellent adhesiveness.

In order to achieve the above object, the present invention provides a primer application step of applying a primer containing hydroperoxide to a predetermined region of an adherend composed of a rubber member, and a primer containing hydroperoxide. An adhesive application step of applying a liquid room temperature curing adhesive to at least a part of the applied area, and applying a primer containing hydroperoxide of the adherend and a liquid room temperature curing adhesive to the applied part, A method for bonding rubber members is provided, comprising a bonding step of bonding a part of an adherend or an adherend different from the adherend to obtain a joint member.

According to the method for bonding rubber members of the present invention, it is possible to provide a method for bonding rubber members having a bonding region with excellent adhesiveness.

Adhering an adherend (first adherend) composed of a rubber member to another adherend (second adherend), or adhering parts of the adherends together (That is, bonding an end or the like of an adherend to an end or the like of the adherend different from the end or the like of the adherend) yields a joining member. In recent years, such joining members are required to have heat resistance and adhesiveness. In the case of bonding the first adherend to the second adherend or bonding parts of the adherend to each other, if conventional instant adhesives or the like are used for bonding, heat resistance and adhesiveness may be affected. may be inferior. In addition, when the first adherend is adhered to the second adherend using only the two-component acrylic adhesive, or when parts of the adherend are adhered to each other, the hardened adhesive and the adherend Peeling occurs at the interface with the body, and adhesion is not sufficient. Therefore, the present inventors used various adhesives, various primers, etc., and as a result of examining various adhesion processes, found that organic peroxides (particularly, hydro After applying a primer containing a peroxide), applying a liquid room temperature curing adhesive, and then bonding another adherend or other part of the adherend and curing the adhesive, the adhesiveness will be reduced. An excellent adhesion region is specifically formed, and the adhesive and the adherend strongly adhere (or the first adherend and the second adherend strongly adhere, or the adherend and other parts of the adherend strongly adhere). The method for bonding rubber members according to the present invention is based on such findings.

Specifically, the method for bonding a rubber member according to the present invention includes a step of applying a primer containing a hydroperoxide to a predetermined region of an adherend made of a rubber member; An adhesive application step of applying a liquid room temperature curable adhesive to at least a part of the area coated with the containing primer, and the primer containing hydroperoxide of the adherend and the liquid room temperature curable adhesive were applied and a bonding step of bonding a part of the adherend or an adherend different from the adherend to the part to obtain a joint member. In addition, from the viewpoint of improving the wettability of the organic peroxide to the adherend, a predetermined area of the adherend may be subjected to surface roughening, polishing, degreasing, UV cleaning, or corona discharge before the primer coating step. It is preferable to include a pretreatment step for performing pretreatment such as treatment, plasma treatment, flame treatment, halogenation treatment, and the like. A bonding member is formed by bonding a first adherend and a second adherend or by bonding a portion of the adherend to another portion of the adherend. In the following description, in principle, an example using a first adherend and a second adherend will be described.

[Adherend]
The first adherend and the second adherend may be made of the same material or may be made of different materials. However, the adherend and the first adherend are configured using a rubber member. Various rubber materials can be used as the rubber material constituting the rubber member, and it is preferable to use a rubber material having heat resistance of 60° C. or more at the high temperature use limit. Examples of the rubber material include natural rubber, chloroprene rubber, urethane rubber, and the like, and it is particularly suitable for bonding diene rubber. In addition, there is no particular limitation on the shape of the adherend, or the first adherend and the second adherend. It can have various shapes as long as it has at least a portion thereof (which is preferably flat).

[Primer]
The primer of the present invention is a primer containing an organic peroxide. In addition, the organic peroxide of the present invention is stable at normal temperature as a single substance, and is easy to handle. Use hydroperoxide. Examples of hydroperoxides include t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide and the like. In addition to using the primer alone, the primer can also be used by diluting it with a predetermined solvent. The predetermined solvent is an organic solvent such as acetone, heptane, methyl ethyl ketone, ethyl acetate, and toluene. In the present invention, the primer further includes other additives such as polymethyl methacrylate, polyvinyl butyral, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, methacrylic acid ester-butadiene-styrene copolymer, methacrylic Thermoplastic resin such as acid ester-butadiene-acrylonitrile-styrene copolymer, rubber such as styrene-butadiene rubber, polybutadiene rubber, polyisoprene rubber, chloroprene rubber, nitrile rubber, chlorinated rubber, acrylic rubber, epichlorohydrin rubber, liquid polybutadiene, Liquid rubbers such as acrylic-terminated liquid polybutadiene and liquid acrylonitrile-butadiene copolymer can be blended. For the purpose of imparting thixotropic properties, thixotropic agents such as finely powdered polyethylene, dibenzylidene-D-sorbitol, cellulose triacetate, stearic acid amide, bentonite and finely powdered silicic acid can be blended. Furthermore, dyes and pigments for coloring can be blended.

[Liquid Room Temperature Curing Adhesive]
Examples of liquid room temperature curing adhesives include acrylic adhesives and epoxy adhesives. As the liquid room temperature curing adhesive, it is preferable to use an acrylic adhesive from the viewpoint of excellent heat resistance and durability and rapid curing. Furthermore, as the acrylic adhesive, a two-component acrylic adhesive having a component A containing a polymerizable vinyl monomer and a component B containing a reducing agent that forms a redox catalyst system between the polymerizable vinyl monomer and a polymerization initiator is used. A system adhesive is preferable, and it is more preferable that agent A is a two-liquid acrylic adhesive further containing a polymerization initiator.

(Polymerizable vinyl monomer)
Various polymerizable vinyl monomers can be used as the polymerizable vinyl monomer. Specifically, various polymerizable vinyl monomers capable of radical polymerization can be used. Examples of polymerizable vinyl monomers include (meth)acrylate, styrene, α-alkylstyrene, divinylbenzene, vinyl ether, divinyl ether, maleic anhydride, maleic acid ester, N-vinylpyrrolidone, 2-vinylpyridine, and acetic acid. Examples include vinyl and vinyl propionate. (Meth)acrylic acid esters are preferred from the viewpoint of having good polymerization reactivity.

(Meth)acrylic acid esters include, for example, compounds represented by the following (i) to (v).

(i) a monomer whose general formula is Z—O—R ¹ ;

In formula (i), Z represents a (meth)acryloyl group, R ¹ is hydrogen or an alkyl group having 1 to 20 carbon atoms, cycloalkyl group, benzyl group, phenyl group, tetrahydrofurfuryl group, glycidyl group, dicyclopentyl group, dicyclopentenyl group, (meth)acryloyl group and isobornyl group.

Examples of the monomer represented by formula (i) include methyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (meth) dicyclopentyl acrylate, dicyclopentenyl (meth)acrylate, glycerol (meth)acrylate, glycerol di(meth)acrylate, isobornyl (meth)acrylate, and (meth)acrylic acid.

(ii) a monomer whose general formula is ZO-(R ² O)pR ¹ ;

In formula (ii), Z and R ¹ are the same as above. R ² represents -C ₂ H ₄ -, -C ₃ H ₆ -, -CH ₂ CH(CH ₃ )-, -C ₄ H ₈ -, or -C ₆ H ₁₂ -, p is 1 Represents an integer from ~25.

Examples of the monomer represented by formula (ii) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ethoxyethyl (meth)acrylate, polyethylene glycol (meth)acrylate, phenoxy ethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, tripropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate and the like.

(iii) the general formula is
Z-(OR ² )qO-pH-C(R ³ ) ₂ -pH-O-(R ² O)qZ
A monomer represented by

In formula (iii), Z and ^R2 are the same as above. R ³ represents hydrogen or an alkyl group having 1 to 4 carbon atoms, q represents an integer of 0 to 8, and pH represents a phenylene group.

Examples of the monomer represented by general formula (iii) include 2,2-bis(4-(meth)acryloxyphenyl)propane, 2,2-bis(4-(meth)acryloxyethoxyphenyl) Propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane, and 2,2-bis(4-(meth) ) EO-modified epoxy (meth)acrylates such as acryloxypolyethoxyphenyl)propane.

(iv) (meth)acrylic acid esters of polyhydric alcohols excluding the monomers represented by general formula (i), general formula (ii), or general formula (iii);

Examples of monomers contained in (iv) include trimethylolpropane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. are mentioned.

(v) A urethane prepolymer having a (meth)acryloyloxy group.

Examples of the monomer contained in (v) include a compound obtained by reacting a (meth)acrylic acid ester having a hydroxyl group, an organic polyisocyanate and a polyhydric alcohol.

Examples of (meth)acrylic acid esters having a hydroxyl group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

(Polymerization initiator)
Various polymerization initiators can be used as the polymerization initiator. It is preferable to use an organic peroxide as the polymerization initiator of the present invention. Examples of organic peroxides as polymerization initiators include t-butyl peroxybenzoate, cumene hydroperoxide, p-menthane hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene dihydroperoxide, and methyl ethyl ketone peroxide. and benzoyl peroxide. Among these, hydroperoxides are preferred, particularly cumene hydro, because they are stable under normal temperature environment, are easy to handle, and can easily initiate reaction under normal temperature environment when used in combination with a reducing agent. Preference is given to using peroxides.

(reducing agent)
As the reducing agent, various compounds can be used in which an organic peroxide used as a polymerization initiator or primer reacts with the reducing agent to generate radicals. Examples of reducing agents include reaction condensates of amines and aldehydes, triethylamine, tripropylamine, tributylamine, N,N-dimethylparatoluidine, 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, tetramethylthiourea, ethylenethiourea, Urea, cobalt naphthenate, copper naphthenate, vanadyl acetylacetonate and the like. Among these, vanadyl acetylacetonate and ethylene thiourea are preferred because of their good reactivity with hydroperoxide.

(Other additives)
When the liquid room temperature curing adhesive or the liquid room temperature curing adhesive is a two-component acrylic adhesive, in addition, in the A agent and / or the B agent, as a modifier, viscosity adjustment and curing of the cured product Polymethyl methacrylate, polyvinyl butyral, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, methacrylate-butadiene-styrene copolymer, methacrylate-butadiene-acrylonitrile for the purpose of improving flexibility - Thermoplastic resins such as styrene copolymers, rubbers such as styrene-butadiene rubber, polybutadiene rubber, polyisoprene rubber, chloroprene rubber, nitrile rubber, chlorinated rubber, acrylic rubber, epichlorohydrin rubber, liquid polybutadiene, terminal acrylic modified liquid polybutadiene, A liquid rubber such as a liquid acrylonitrile-butadiene copolymer can be blended. For the purpose of imparting thixotropic properties, thixotropic agents such as finely powdered polyethylene, dibenzylidene-D-sorbitol, cellulose triacetate, stearic acid amide, bentonite and finely powdered silicic acid can be blended. Furthermore, paraffin, beeswax, etc. for improving the curability of the air contact surface, and dyes and pigments for coloring can be blended.

[Method of adhering rubber members]
As described above, the rubber member bonding method of the present invention includes a pretreatment step, a primer application step, an adhesive application step, and/or a bonding step.

(Pretreatment step)
The pretreatment step is performed on the area of the first adherend and/or the second adherend where the primer and/or the liquid room temperature curing adhesive is to be applied (hereinafter simply referred to as "predetermined area"). This is a step of applying a predetermined pretreatment. As the pretreatment, for example, a predetermined area is roughened using a file such as sandpaper, a polishing process, and/or a cleaning agent or an organic solvent such as acetone or methyl ethyl ketone is used to clean the surface of the predetermined area. / degreasing treatment. When only one adherend is used, pretreatment is applied to a predetermined region of the adherend.

(Primer application process)
The primer application step is a step of applying a hydroperoxide-containing primer to a predetermined region of the first adherend and/or the second adherend, which are made of a rubber member. In the primer application step, a primer containing hydroperoxide alone or a hydroperoxide containing a predetermined solvent and other additives added as necessary is applied to a predetermined region. It should be noted that the predetermined region is preferably pretreated in the pretreatment step. Further, the primer application step may include a drying step of drying the primer after applying the primer. When only one adherend is used, a primer containing hydroperoxide is applied to a predetermined region of the adherend.

(Adhesive application process)
The adhesive application step is a step of applying a liquid room temperature curing adhesive to at least a part of the region coated with the hydroperoxide-containing primer after the primer application step. When a two-liquid acrylic adhesive is used as the liquid room temperature curable adhesive, the adhesive application step includes a step of preparing agent A and agent B, a step of mixing agent A and agent B, and mixing the mixture. The step of applying a primer containing hydroperoxide to at least a portion of the coated area is included. In addition, you may mix A agent and B agent on a predetermined area|region. The reaction between the hydroperoxide and the reducing agent contained in the liquid room temperature curable adhesive proceeds when the primer containing hydroperoxide and the liquid room temperature curable adhesive come into contact with each other. The coating method of the primer coating step and the adhesive coating step is not particularly limited, and a method of coating with a brush or the like, a method of coating with a spray, or the like can be used.

(Lamination process)
In the lamination step, the portion of the first adherend and / or the second adherend on which the primer containing hydroperoxide and the liquid room temperature curing adhesive is applied is applied to the first adherend. This is a step of bonding different second adherends to produce a joining member. In addition, when only one adherend is used, another part of the adherend is attached to the part of the adherend to which the primer containing hydroperoxide and the liquid room temperature curing adhesive is applied. A joining member is produced. When the liquid room temperature curing adhesive is cured, the first adherend and the second adherend are adhered (when only one adherend is used, part of the adherend and the adherend are bonded together). A different part of the body is adhered), and the part where the liquid room temperature curing adhesive is cured becomes the adhesion region. Thereby, a joining member is obtained. The liquid room temperature curing adhesive is cured by being left at room temperature (23° C.) for a predetermined time (for example, 12 hours). Moreover, from the viewpoint of improving the curing speed, a heating treatment may be performed.

In addition, it is preferable that the A agent of the liquid room temperature curing adhesive contains a polymerization initiator, and examples of the polymerization initiator include organic peroxides. In the case where the polymerization initiator contained in agent A is an organic peroxide, if no primer is used, the adherend and other parts of the adherend, or the first adherend and the second It does not adhere to the adherend within a range that can withstand practical use. This suggests that even if the agent A contains an organic peroxide, this organic peroxide does not substantially exert an effect as a primer on the surface of the adherend. That is, the presence of hydroperoxide as an organic peroxide on the surface of the adherend (that is, direct application of a primer containing hydroperoxide to the surface of the adherend) It is presumed that this contributes to improving the adhesive strength between a part of the body and another part, or between the first adherend and the second adherend.

In addition, the adhesive strength of the first adherend to the second adherend (or the adhesive strength of the second adherend to the first adherend) is When a predetermined force is applied to the bonding member so that the bonding region composed of the primer containing hydroperoxide and the liquid room temperature curing adhesive moves in the peeling direction, the bonding region preferably has the following peel strength.

a) At least one of a part or other part of the adherend, or at least one of the first adherend or the second adherend is completely stretched, making further measurement impossible and/or b) from within a portion or other portion of the adherend or the first or second adherend. Destruction from the inside of at least one of (material destruction) separates a part of the adherend from another part, or separates the first adherend from the second adherend The adhesive area should have peel strength.

In addition, it is more preferable that the adhesive region has heat resistance that can maintain physical properties even after being left in an environment of 100° C. or higher for 24 hours.

[Effects of Embodiment]
In the method of bonding a rubber member according to the present invention, a hydroperoxide is applied to the surface of an adherend composed of a rubber member, and a liquid room temperature curing adhesive is applied to the surface of the adherend. Laminating parts or other adherends together. A bonding member obtained by bonding an adherend and another part of the adherend by directly applying a primer containing hydroperoxide to the surface of the adherend made of a rubber material, or the first In the joining member obtained by bonding the adherend and the second adherend together, the adherends or the first adherend and the second adherend are strongly adhered to each other. In addition, the effect of exhibiting good heat resistance in the adhesive region is also desired. As a result, a bonding member having excellent adhesion and/or heat resistance and durability can be produced. The rubber member bonding method of the present invention can be used in various industrial fields such as various electrical and electronic fields, automobiles, buildings, and civil engineering.

The present invention will be described more specifically with reference to examples below. In addition, it cannot be overemphasized that these examples are illustrations and should not be interpreted restrictively.

(Example 1)
In Example 1, a first adherend and a second adherend made of natural rubber (NR) were prepared. Each of the first adherend and the second adherend was a test piece made of natural rubber (trade name: NB603, manufactured by Nitto Kako Co., Ltd.) measuring 150 mm long×20 mm wide×2 mm thick. Then, a region of 100 mm in length × 20 mm in width from one end in the longitudinal direction of the first adherend and the second adherend was polished with sandpaper (#100) until the surface gloss disappeared, and then methyl ethyl ketone ( MEK) was used to perform degreasing treatment (washing treatment) (pretreatment step). Next, a pretreated first adherend and a second adherend are prepared, and the pretreated regions (regions of both the first adherend and the second adherend) As a primer, cumene hydroperoxide (CHP, trade name: Permil (registered trademark) H, manufactured by NOF Corporation) was applied with a brush and dried for several minutes (primer application step). Subsequently, a two-liquid acrylic adhesive (trade name: Y630D, manufactured by Cemedine Co., Ltd.), which is a liquid room temperature curing adhesive, was applied to each of the CHP-coated regions of both the first adherend and the second adherend. is applied to a thickness of about 0.2 mm (adhesive application step), the second adherend is attached to the first adherend, and a weight of about 100 g is placed and fixed, 23 ° C. 50% RH The adhesive was cured by being left in the environment for 12 hours (bonding step). As a result, a joint member according to Example 1 (adhesion test piece according to Example 1) was obtained. Then, the bonding member according to Example 1 thus obtained was subjected to predetermined evaluation.

(Adhesion evaluation)
The adhesion test piece according to Example 1 was subjected to a T-shaped peel test (tensile speed 100 mm / min) using Autograph AG-I (manufactured by Shimadzu Corporation) in an environment of 23 ° C., and the adhesion was evaluated. It was evaluated according to the following evaluation method.

○: No peeling, or the rate of member breakage is 70% or more.
Δ: When member destruction is 40% or more and less than 70%.
x: In the case of interfacial failure, or in the case of less than 40% member failure.

(Example 2)
Unlike Example 1, Example 2 uses 1,1,3,3-tetramethylbutyl hydroperoxide (trade name: Perocta (registered trademark) H, manufactured by NOF Corporation) as a primer containing hydroperoxide. A joint member according to Example 2 was produced and evaluated in the same manner as in Example 1, except that the was used.

(Example 3)
In Example 3, unlike Example 1, a joint member according to Example 3 was produced and evaluated in the same manner as in Example 1, except that CHP was diluted with a solvent, methyl ethyl ketone (MEK). 50 parts by weight of CHP was dissolved in 50 parts by weight of MEK.

(Example 4)
In Example 4, unlike Example 1, a bonding member according to Example 4 was produced and evaluated in the same manner as in Example 1, except that CHP was diluted with heptane, which is a solvent. 50 parts by weight of CHP was dissolved in 50 parts by weight of heptane.

(Example 5)
Example 5 is different from Example 1 except that only the B component of a two-liquid acrylic adhesive (trade name: Y630D, manufactured by Cemedine Co., Ltd.), which is a liquid room temperature curing adhesive, was used (i.e., excessive A joining member according to Example 5 was produced and evaluated in the same manner as in Example 1, except that agent A containing oxide was not used.

(Example 6)
In Example 6, unlike Example 3, a joint member according to Example 6 was produced and evaluated in the same manner as in Example 3, except that the degreasing treatment using MEK was omitted in the pretreatment step.

(Example 7)
Example 7 differs from Example 1 in that the joining member according to Example 7 was manufactured in the same manner as in Example 1, except that chloroprene rubber (CR) was used as the adherend instead of natural rubber (NR). made and evaluated.

(Comparative example 1)
In Comparative Example 1, a bonding member according to Comparative Example 1 was produced and evaluated in the same manner as in Example 1, except that the primer coating step was omitted.

(Comparative example 2)
In Comparative Example 2, unlike Example 1, instead of a primer containing hydroperoxide, di-t-hexyl peroxide (trade name: Perhexyl (registered trademark) D, manufactured by NOF Corporation), which is a dialkyl peroxide, was used. A joint member according to Comparative Example 2 was produced and evaluated in the same manner as in Example 1 except that it was used.

(Comparative Example 3)
Comparative Example 3 differs from Example 1 in that ethyl 1,1,3,3-tetramethylbutylperoxy-2-hexanoate (trade name: Perocta ( A joint member according to Comparative Example 3 was produced and evaluated in the same manner as in Example 1, except that O-70 (S), manufactured by NOF Corporation) was used.

(Comparative Example 4)
Unlike Example 1, Comparative Example 4 is not a primer containing hydroperoxide, but a primer containing a reducing agent (copper neodecanoate (manufactured by Nippon Kagaku Sangyo Co., Ltd.) 1 part by weight, n-butyraldehyde aniline (product Name: Noccellar (registered trademark) 8, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) 30 parts by weight, MEK 70 parts by weight) was used in the same manner as in Example 1, except that a joint member according to Comparative Example 4 was manufactured. made and evaluated.

Table 1 shows each treatment in each step and the materials used. In addition, the results of evaluating the obtained joining members are shown. In addition, in the process contents and materials used in Table 1, the unit of numerical values in the column of compounds is parts by weight, and the columns of adopted processes and used materials are marked with "O".

As can be seen by referring to Table 1, all of the bonding members according to Examples 1 to 7 were evaluated for adhesiveness as "◯" or "Δ", indicating that they had good adhesiveness.

Although the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the scope of the invention according to the claims. In addition, not all combinations of features described in the embodiments and examples are essential to the means for solving the problems of the invention, and various It should be noted that variations are possible.

Claims (3)

A primer application step of applying a primer containing hydroperoxide to a predetermined region of an adherend formed using a rubber member having heat resistance of 60 ° C. or higher ;
an adhesive applying step of applying a liquid room temperature curing adhesive to at least a part of the region to which the primer containing the hydroperoxide is applied;
A part of the adherend or an adherend different from the adherend is attached to a portion of the adherend to which the primer containing the hydroperoxide and the liquid room temperature curing adhesive are applied. a bonding step of obtaining a joint member by
The different adherend is configured using a rubber member having heat resistance of 60 ° C. or higher,
The liquid room-temperature-curable adhesive comprises a two-liquid component comprising a component A containing a polymerizable vinyl monomer and a component B containing a reducing agent that forms a redox catalyst system with the polymerizable vinyl monomer and a polymerization initiator. A method for bonding a rubber member that is an acrylic adhesive . 2. The bonding method according to claim 1 , further comprising a pretreatment step of applying a pretreatment to said predetermined region before said primer application step. 3. A method for producing a joint member obtained by bonding parts of the adherends or by bonding the adherends and an adherend different from the adherends by the bonding method according to claim 1 or 2 .