Method for manufacturing a rubber-metal joint, adhesive sheet and adhesive sheet

Abstract

To provide a method for manufacturing a rubber metal joined body excellent in working property in which unvulcanized rubber and metal are joined together.SOLUTION: A method for manufacturing a rubber metal joined body in which unvulcanized rubber and metal are joined together includes: an unvulcanized rubber metal laminate forming step of laminating the unvulcanized rubber, an adhesive sheet and the metal in this order; and a vulcanization adhesion step of simultaneously adhering the unvulcanized rubber and the metal with the adhesive sheet by heating and pressurizing the unvulcanized rubber metal laminate. The adhesive sheet includes a vulcanized adhesive layer and a tackifying adhesive layer in this order from a side of the unvulcanized rubber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a rubber-metal bonded body in which an unvulcanized rubber and a metal are bonded. The present invention also relates to an adhesive sheet and an adhesive sheet for bonding an unvulcanized rubber and a metal.

Background Art

[0002] As a method for bonding a rubber material and a material of another material such as metal, a vulcanization bonding method is generally used.

[0003] For example, in Patent Document 1, as a vulcanization adhesive, a method is disclosed in which a primer adhesive and a topcoat adhesive are applied to a metal and then heat-treated under predetermined conditions to bake the metal. This prevents the flow of the adhesive due to the injection of the unvulcanized rubber in the vulcanization process and eliminates poor rubber adhesion. On the other hand, since the above method uses volatile organic compounds, improvement is desired from the viewpoints of environment and safety. Also, there is room for improvement in the uniformity of the film thickness and the coating efficiency in the application of the adhesive.

[0004] Therefore, in Patent Document 2, an adhesive sheet is disclosed which comprises an upper coating adhesive layer made of a solvent-dispersed vulcanization adhesive reactive with rubber on one surface and a primer adhesive layer reactive with metal on the other surface with respect to a film made of a polymer. Thereby, before the bonding step, the volatile components in the adhesive can be removed by volatilization in advance, and the film thickness can also be easily made uniform.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, conventional methods for joining unvulcanized rubber to metal all require two or more heating and pressurizing processes, so improvements in workability were desired.

[0007] Therefore, the present invention aims to provide a method for manufacturing a rubber-metal joint in which unvulcanized rubber and metal are joined, with excellent workability. The present invention also aims to provide an adhesive sheet and an adhesive sheet for joining unvulcanized rubber and metal, which can be suitably used in the above manufacturing method. [Means for solving the problem]

[0008] As mentioned earlier, conventional methods for joining unvulcanized rubber and metal require two or more heating and pressing processes. Specifically, metal is laminated to one side of an adhesive sheet, and the metal is bonded in the first heating and pressing process. Then, unvulcanized rubber is laminated to the other side, and the unvulcanized rubber is vulcanized and bonded in the second heating and pressing process. This is because the adhesive sheet is brittle and difficult to handle, and furthermore, because the surface of the adhesive sheet has almost no tack, it is not possible to perform temporary bonding before vulcanization bonding of the unvulcanized rubber and metal.

[0009] The inventors of the present invention have found that the above problems can be solved by providing a viscous adhesive layer in addition to the conventional vulcanizing adhesive layer in an adhesive sheet used to bond unvulcanized rubber and metal, and have completed the present invention. That is, the present invention relates to the following aspects.

[0010] 《Aspect 1》 A method for manufacturing a rubber-metal joint in which unvulcanized rubber and metal are joined, A process for forming an unvulcanized rubber-metal laminate, in which the unvulcanized rubber, adhesive sheet, and metal are laminated in this order, and The process includes a vulcanization bonding step in which the unvulcanized rubber-metal laminate is heated and pressurized to bond the unvulcanized rubber and the metal to the adhesive sheet simultaneously. The adhesive sheet comprises, in order from the unvulcanized rubber side, a vulcanizing adhesive layer and a viscous adhesive layer, in a method for manufacturing a rubber-metal joint. 《Aspect 2》 The method for manufacturing a rubber-metal bond according to Embodiment 1, wherein the adhesive sheet includes the vulcanizing adhesive layer in the outermost layer located on the unvulcanized rubber side, and the adhesive layer in the outermost layer located on the metal side. 《Aspect 3》 A method for producing a rubber-metal bond according to embodiment 1 or 2, wherein the vulcanizing adhesive layer contains a halogenated polyolefin. Appearance 4 The method for producing a rubber-metal bond according to embodiment 3, wherein the adhesive layer comprises a composition containing 30 to 60% by mass of halogenated polyolefin, 30 to 60% by mass of resol-type phenolic resin, and 1 to 40% by mass of xylene resin. Appearance 5 The method for producing a rubber-metal bond according to Embodiment 3, wherein the adhesive layer comprises a composition containing an epoxy resin mixture, a latent curing agent, and a curing accelerator, the epoxy resin mixture contains 40 to 60% by mass of epoxy resin (A) having a weight-average molecular weight (Mw) of 10,000 to 80,000, and 40 to 60% by mass of epoxy resin (B) having a weight-average molecular weight (Mw) of 200 to 1,000, and the adhesive sheet contains 1 to 20 parts by mass of the latent curing agent and 0.1 to 5 parts by mass of the curing accelerator per 100 parts by mass of the epoxy resin mixture. 《Aspect 6》 An adhesive sheet for joining unvulcanized rubber and metal, used together with a vulcanizing adhesive layer, wherein the adhesive sheet comprises a composition containing 30-60% by mass of halogenated polyolefin, 30-60% by mass of resol-type phenolic resin, and 1-40% by mass of xylene resin. Appearance 7 An adhesive sheet for joining unvulcanized rubber and metal, used together with a vulcanizing adhesive layer, wherein the adhesive sheet comprises a composition containing an epoxy resin mixture, a latent curing agent and a curing accelerator, the epoxy resin mixture containing 40-60% by mass of epoxy resin (A) having a weight-average molecular weight (Mw) of 10,000-80,000 and 40-60% by mass of epoxy resin (B) having a weight-average molecular weight (Mw) of 200-1,000, and the adhesive sheet comprising 1-20 parts by mass of the latent curing agent and 0.1-5 parts by mass of the curing accelerator per 100 parts by mass of the epoxy resin mixture. 《Aspect 8》 An adhesive sheet comprising the adhesive sheet described in embodiment 6 or 7, and a vulcanizing adhesive layer. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower limit and upper limit.

[0012] <Method for manufacturing rubber-metal joints> The method for manufacturing a rubber-metal bond according to this embodiment is a method for manufacturing a rubber-metal bond obtained by joining unvulcanized rubber and metal, and includes the following steps 1 and 2. Step 1: Laminating unvulcanized rubber, adhesive sheet, and metal in this order; process for forming an unvulcanized rubber-metal laminate. Step 2: A vulcanization bonding process in which the unvulcanized rubber-metal laminate obtained in Step 1 is heated and pressurized, and the unvulcanized rubber and the metal are simultaneously bonded to the adhesive sheet. Here, the adhesive sheet in step 1 above includes, in order from the unvulcanized rubber side, a vulcanizing adhesive layer and a viscous adhesive layer.

[0013] (Process 1) In step 1, unvulcanized rubber, an adhesive sheet, and metal are laminated in this order to form an unvulcanized rubber-metal laminate. Subsequently, the adhesive sheet includes a vulcanizing adhesive layer and an adhesive layer in order from the unvulcanized rubber side. The adhesive sheet only needs to be able to temporarily bond both the unvulcanized rubber and the metal, so that in the subsequent vulcanizing adhesion process, the unvulcanized rubber and the metal can be simultaneously adhered to the adhesive sheet.

[0014] [Adhesive sheet] From the perspective of vulcanizing adhesion to the unvulcanized rubber, it is preferable that the outermost layer located on the vulcanized rubber side of the adhesive sheet includes a vulcanizing adhesive layer, and the vulcanizing adhesive layer is brought into contact with the unvulcanized rubber. Also, from the perspective of adhesion to the metal, it is preferable that the outermost layer located on the metal side of the adhesive sheet includes an adhesive layer, and the adhesive layer is brought into contact with the metal. More preferably, the adhesive sheet includes a vulcanizing adhesive layer in the outermost layer located on the unvulcanized rubber side and an adhesive layer in the outermost layer located on the metal side.

[0015] ·Vulcanizing adhesive layer For the vulcanizing adhesive layer in the adhesive sheet, a conventionally known adhesive that can vulcanize and adhere to the unvulcanized rubber can be used. Examples of the adhesive include adhesives containing halogenated polyolefins. Among them, examples of the halogenated polyolefin adhesives include Chemlok (trademark) 252X (product name, manufactured by LORD Corporation), Chemlok (trademark) 6108 (product name, manufactured by LORD Corporation), Metalok XF572 (product name, manufactured by Toyo Chemical Research Institute), etc. Also, the halogenated polyolefins used in the following adhesive layers can also be used.

[0016] The adhesive is formed by coating or the like on a peelable film. The coating method is not particularly limited, and examples include coating using a coating roller such as a doctor blade, coating by the microgravure (trademark) roll coating method, coating by the slot die coating method, coating by the reverse roll coating method, coating by the knife coating method, etc.

[0017] After applying the adhesive, heat treatment is performed to volatilize and dry the solvent, and a vulcanizing adhesive layer is formed.

[0018] The thickness of the vulcanizing adhesive layer is not particularly limited, but is usually 5 to 30 μm, and especially around 10 to 20 μm.

[0019] ·Adhesive layer The adhesive layer in the adhesive sheet should be able to temporarily bond the objects to be bonded, and then bond them together through heating and pressurizing in step 2. For example, it is sufficient for the layer to be in a semi-cured state until heating and pressurizing in step 2. Semi-cured means that it contains a certain proportion of unreacted and uncured components, and has a moderate tack. These unreacted and uncured components undergo a complete curing reaction upon heating in step 2.

[0020] The adhesive layer is composed of a composition containing, for example, a thermosetting resin. Examples of thermosetting resins include halogenated polyolefins and epoxy resins. The above composition may contain only one type of thermosetting resin, or two or more types. It may also contain components other than thermosetting resins.

[0021] When the composition constituting the adhesive layer includes a halogenated polyolefin as a thermosetting resin, examples of halogenated polyolefins include chlorinated polyolefins and fluorinated polyolefins.

[0022] From the viewpoint of excellent adhesion and reasonable handling, chlorinated polyolefins are preferred, chlorosulfonated polyolefins are more preferred, and chlorosulfonated polyethylene is even more preferred.

[0023] The chlorine content in chlorosulfonated polyolefins is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of excellent adhesion and appropriate handling. Furthermore, the chlorine content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0024] When the chlorosulfonated polyolefin is chlorosulfonated polyethylene, the viscosity of the chlorosulfonated polyethylene in a 25% by weight toluene solution is preferably 200 mPa·s or higher, more preferably 250 mPa·s or higher, and even more preferably 300 mPa·s or higher, from the viewpoint of ease of processing into a sheet. Furthermore, it is preferably 2000 mPa·s or lower, more preferably 1800 mPa·s or lower, and even more preferably 1600 mPa·s or lower.

[0025] Here, the viscosity of a 25% by weight toluene solution refers to the viscosity measurement of a 25% by weight toluene solution of chlorosulfonated polyethylene at 23°C using a Brookfield viscometer.

[0026] The weight-average molecular weight Mw of the halogenated polyolefin is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, from the viewpoint of excellent adhesion. Furthermore, the weight-average molecular weight Mw is preferably 500,000 or less, more preferably 450,000 or less, and even more preferably 400,000 or less.

[0027] The composition constituting the adhesive layer preferably includes, in addition to the halogenated polyolefin mentioned above, a phenol resin, a xylene resin, or other resins, and more preferably contains a phenol resin and a xylene resin, from the viewpoint of excellent curability and adhesion.

[0028] The phenolic resin may be of the resol or novolac type, but from the viewpoint of excellent curability, the resol type phenolic resin is particularly preferred.

[0029] When the composition constituting the adhesive layer includes a halogenated polyolefin, a resol-type phenolic resin, and a xylene resin, the following preferred amounts of each in the composition are as follows.

[0030] The content of halogenated polyolefin in the composition is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of excellent adhesion. The above content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0031] The content of the resol-type phenolic resin in the composition is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of excellent curability. The above content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0032] When the composition constituting the adhesive layer also includes the above-mentioned xylene resin, the content of the xylene resin in the composition is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of excellent tackiness. The above content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0033] From the viewpoint of excellent adhesiveness, the number-average molecular weight (Mn) of the xylene resin is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. Furthermore, the number-average molecular weight (Mn) is preferably 1000 or less, more preferably 900 or less, and even more preferably 800 or less.

[0034] When the composition constituting the adhesive layer includes an epoxy resin as a thermosetting resin, it is preferable to include an epoxy resin mixture containing two or more epoxy resins with different molecular weights, from the viewpoint of easily optimizing the balance between tackiness and adhesion.

[0035] The epoxy resin mixture preferably contains epoxy resin (A) with a weight-average molecular weight Mw of 10,000 to 80,000 and epoxy resin (B) with a weight-average molecular weight Mw of 200 to 1,000. The epoxy resin mixture may contain one or more epoxy resins corresponding to epoxy resin (A), and may contain one or more epoxy resins corresponding to epoxy resin (B).

[0036] The weight-average molecular weight Mw of epoxy resin (A) is 10,000 to 80,000, but from the viewpoint of excellent adhesion, it is preferably 20,000 or more, and more preferably 40,000 or more. Furthermore, the above weight-average molecular weight Mw is preferably 70,000 or less, and more preferably 60,000 or less.

[0037] The weight-average molecular weight Mw of epoxy resin (B) is 200 to 1000, but from the viewpoint of excellent tackiness, it is preferably 250 or higher, and more preferably 300 or higher. Furthermore, the above weight-average molecular weight Mw is preferably 800 or lower, and more preferably 500 or lower.

[0038] The content of epoxy resin (A) having a weight-average molecular weight Mw of 10,000 to 80,000 in the epoxy resin mixture is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of excellent adhesion. The above content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. When epoxy resin (A) contains two or more types of epoxy resins, it is preferable that the total content of them is within the above range.

[0039] The content of epoxy resin (B) having a weight-average molecular weight Mw of 200 to 1000 in the epoxy resin mixture is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of excellent tackiness. The above content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. When epoxy resin (B) contains two or more types of epoxy resins, it is preferable that the total content of them is within the above range.

[0040] The composition constituting the adhesive layer preferably includes, in addition to the epoxy resin, a latent curing agent, a curing accelerator, etc., from the viewpoint of adhesion and productivity, and more preferably includes a latent curing agent and a curing accelerator.

[0041] A latent curing agent is a curing agent that balances storage stability and reactivity. It exists stably at room temperature without reacting, but is activated by heat. Conventionally known latent curing agents can be used, such as dicyandiamide, amine compounds, and imidazole compounds, with dicyandiamide being the most preferred among them.

[0042] Conventional curing accelerators can be used, including, for example, tertiary amine compounds, imidazole compounds, and phosphorus compounds, with imidazole compounds and tertiary amine compounds being preferred.

[0043] When the composition constituting the adhesive layer includes an epoxy resin, a latent curing agent, and a curing accelerator, the content of the latent curing agent per 100 parts by mass of epoxy resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, from the viewpoint of curability and adhesion. The above content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Note that 100 parts by mass of epoxy resin refers to the total content of the epoxy resin.

[0044] From the viewpoint of curability, the content of the curing accelerator per 100 parts by mass of epoxy resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more. The above content is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. Note that 100 parts by mass of epoxy resin refers to the total content of the epoxy resin.

[0045] The adhesive strength of the adhesive layer is preferably 0.1 N / 25 mm or higher, more preferably 0.2 N / 25 mm or higher, and even more preferably 0.3 N / 25 mm or higher, from the viewpoint of having high temporary adhesive strength before heating and pressurizing in step 2 and sufficiently fixing the objects to be bonded. Furthermore, although there is no particular upper limit to the adhesive strength, from the viewpoint of making it easy to reattach the adhesive even if the bonding position is incorrect during temporary bonding, it is preferably 30 N / 25 mm or lower, more preferably 20 N / 25 mm or lower, and even more preferably 10 N / 25 mm or lower.

[0046] The composition constituting the adhesive layer is applied to the vulcanizing adhesive layer using a solvent or other solvent as needed. If the adhesive sheet includes other layers, such as a primer layer described later, between the vulcanizing adhesive layer and the adhesive layer, the above composition is applied on top of such other layers.

[0047] Alternatively, the above composition may be applied to a release film to form a unique adhesive layer, and then this adhesive layer may be bonded to the vulcanizing adhesive layer or the other layer.

[0048] The method for applying the above composition is not particularly limited, and examples include application using an application roller such as a doctor blade, application by microgravure™ roll coating, application by slot die coating, application by reverse roll coating, application by knife coating, etc., similar to when forming the above vulcanizing adhesive layer.

[0049] After applying the composition, the solvent is evaporated and dried by heat treatment, forming an adhesive layer.

[0050] The heat treatment is carried out at a temperature lower than the temperature at which the composition hardens, for example, preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower. The lower limit of the temperature is not particularly limited, but is usually 50°C or higher.

[0051] The heating time is not particularly limited, but for example, 0.5 minutes or more is preferred, 1 minute or more is more preferred, 3 minutes or more is even more preferred, 30 minutes or less is preferred, 10 minutes or less is more preferred, and 5 minutes or less is even more preferred.

[0052] The thickness of the adhesive layer is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, from the viewpoint of adhesion and handling. Furthermore, the thickness of the adhesive layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0053] The adhesive layer formed as described above is flexible, so it does not crack or chip due to brittleness, and has excellent workability.

[0054] Other layers In addition to the vulcanizing adhesive layer and the adhesive layer, the adhesive sheet may also contain other layers, as long as they do not impair the effects of the present invention.

[0055] Other layers can be conventionally known layers, such as a phenol resin layer called a primer layer. These other layers can be formed by conventionally known methods.

[0056] The other layers are preferably formed between the vulcanizing adhesive layer and the adhesive layer so that the vulcanizing adhesive layer is in direct contact with the unvulcanized rubber and the adhesive layer is in direct contact with the metal.

[0057] The thickness of the other layers is not particularly limited, but is usually 3 to 30 μm, and especially 5 to 15 μm.

[0058] [Unvulcanized rubber, metal] Unvulcanized rubber and metals can be those that are conventionally known, and should be selected appropriately according to the purpose.

[0059] Unvulcanized rubber is bonded to one surface of the adhesive sheet, preferably the surface facing the vulcanized adhesive layer, and metallic rubber is bonded to the other surface, preferably the surface facing the adhesive layer. This forms an unvulcanized rubber-metal laminate.

[0060] (Process 2) In step 2, the unvulcanized rubber-metal laminate obtained in step 1 is heated and pressurized to simultaneously bond the unvulcanized rubber and metal in the unvulcanized rubber-metal laminate to the adhesive sheet. The unvulcanized rubber is then vulcanized and bonded to the adhesive sheet.

[0061] Conventional methods for manufacturing rubber-metal joints, which bond unvulcanized rubber and metal, require multiple heating cycles, and the vulcanization and bonding of the unvulcanized rubber to the adhesive sheet and the bonding of the metal are performed separately.

[0062] In contrast, the manufacturing method according to this embodiment allows for the simultaneous bonding of unvulcanized rubber and metal to the adhesive sheet, eliminating the need for multiple heating and pressurizing cycles. However, this does not preclude the possibility of multiple heating and pressurizing cycles.

[0063] From the viewpoint of curing properties, the heating temperature for simultaneously bonding unvulcanized rubber and metal to an adhesive sheet is preferably 120°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher. Furthermore, from the viewpoint of suppressing thermal degradation, the heating temperature is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower.

[0064] The pressure applied to bond the unvulcanized rubber and metal to the adhesive sheet simultaneously is performed at the same time as the heating described above. From the viewpoint of ensuring sufficient adhesion between the unvulcanized rubber and metal, the applied load is preferably 100N or more, more preferably 300N or more, and even more preferably 500N or more. Furthermore, from the viewpoint of productivity, the applied load is preferably 2000N or less, more preferably 1000N or less, and even more preferably 800N or less.

[0065] The heating and pressurizing time for simultaneously bonding unvulcanized rubber and metal to an adhesive sheet is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more, from the viewpoint of ensuring sufficient bonding between the unvulcanized rubber and metal. Furthermore, from the viewpoint of suppressing thermal degradation, the heating and pressurizing time is preferably 30 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less.

[0066] The rubber-metal bond obtained by the above method, in which unvulcanized rubber and metal are joined, has adhesive strength equivalent to that obtained when conventional adhesive sheets are used for joining. The reason for this is not clear, but it is thought that when each layer is temporarily softened by heating during the vulcanization bonding process, the components of each layer partially mix or integrate near the interface of each layer.

[0067] <Adhesive Sheet> The adhesive sheet according to this embodiment is a sheet for joining unvulcanized rubber and metal, and is used together with a vulcanizing adhesive layer. In other words, the adhesive sheet is the same as the sheet consisting of the adhesive layer in (Step 1) [Adhesive Sheet] in the above-mentioned <Method for Manufacturing a Rubber-Metal Joint>, and the preferred embodiment is also the same.

[0068] In one embodiment of the adhesive sheet according to this embodiment, the adhesive sheet comprises a composition containing 30 to 60% by mass of halogenated polyolefin, 30 to 60% by mass of resol-type phenolic resin, and 1 to 40% by mass of xylene resin.

[0069] In another embodiment, the adhesive sheet comprises a composition containing an epoxy resin mixture, a latent curing agent, and an imidazole compound curing accelerator. The epoxy resin mixture contains 40 to 60% by mass of epoxy resin (A) having a weight-average molecular weight (Mw) of 10,000 to 80,000, and 40 to 60% by mass of epoxy resin (B) having a weight-average molecular weight (Mw) of 200 to 1,000. The adhesive sheet contains 1 to 20 parts by mass of latent curing agent and 0.1 to 5 parts by mass of curing accelerator per 100 parts by mass of the epoxy resin mixture.

[0070] As described above in the section on the adhesive layer, the adhesive sheet according to this embodiment is flexible and therefore does not crack or chip due to brittleness. For this reason, it offers particularly excellent workability when used as an adhesive sheet for manufacturing rubber-metal joints.

[0071] The vulcanized adhesive layer used together with the adhesive sheet is the same as the vulcanized adhesive layer in (Step 1) [Adhesive Sheet] in the above-described method for manufacturing a rubber-metal joint, and the preferred embodiment is also the same.

[0072] Furthermore, the adhesive sheet may have a protective layer on the outermost layer of at least one of its main surfaces, but from the viewpoint of ease of handling, it is preferable to have a protective layer on the outermost layer of both main surfaces.

[0073] When using an adhesive sheet together with a vulcanizing adhesive layer, the protective layer is peeled off from the adhesive sheet before use.

[0074] The protective layer can be made of conventionally known materials, such as paper sheets or sheets made of polymer compounds. Examples of polymer compounds include nylon, polypropylene, polyethylene, polyester, and polyimide. From the viewpoint of heat resistance, polyester and polyimide are preferred, and polyethylene terephthalate (PET) is more preferred among them.

[0075] The surface of the protective layer sheet, on the side facing the adhesive sheet, may be subjected to a release treatment as needed. This release treatment can employ conventionally known methods, such as roughening the surface by embossing to create an air layer, or applying a release agent.

[0076] <Adhesive Sheet> The adhesive sheet according to this embodiment includes an adhesive sheet and a vulcanizing adhesive layer, and is used to bond unvulcanized rubber and metal.

[0077] The adhesive sheet is the same as the adhesive sheet described above in <Adhesive Sheet>. That is, it is the same as the sheet consisting of the adhesive layer in (Step 1) [Adhesive Sheet] in the <Method for Manufacturing a Rubber-Metal Joint> described above, and the preferred embodiment is also the same.

[0078] Furthermore, the vulcanizing adhesive layer is the same as the vulcanizing adhesive layer described in the <adhesive sheet> above. That is, it is the same as the vulcanizing adhesive layer in (Step 1) [adhesive sheet] in the <method for manufacturing a rubber-metal bond> above, and the preferred embodiment is also the same.

[0079] Furthermore, the adhesive sheet may have a protective layer on the outermost layer of at least one of its main surfaces, but from the viewpoint of ease of handling, it is preferable to have a protective layer on the outermost layer of both main surfaces. When using an adhesive sheet to bond unvulcanized rubber and metal, the protective layer is peeled off from the adhesive sheet before use.

[0080] A conventionally known protective layer can be used; for example, the same type of protective layer as in the above-mentioned <adhesive sheet> can be used. [Examples]

[0081] The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

[0082] <Example 1> (Manufacturing of adhesive layers (adhesive sheets)) A composition constituting the adhesive layer was prepared by mixing 40 parts by mass of chlorosulfonated polyethylene (manufactured by Tosoh Corporation, CN-1500, chlorine content 30% by mass (Tosoh Research and Technical Report Vol. 45 (2001))), 50 parts by mass of resol-type phenolic resin (manufactured by DIC Corporation, TD-2620), and 10 parts by mass of xylene resin (manufactured by Fudo Co., Ltd., Nikanol LLL).

[0083] The obtained composition was applied to a 38 μm thick PET film that had undergone a peeling treatment using a doctor blade, and treated at 80°C for 4 minutes to obtain a 15 μm thick adhesive layer.

[0084] The exposed surface of the resulting adhesive layer was bonded to the release-treated side of a 38 μm thick PET film as a protective layer, thereby obtaining an adhesive sheet sandwiched between two PET films.

[0085] (Manufacturing of adhesive sheets) On a 38 μm thick PET film that had been peeled, a chlorinated rubber-based vulcanizing adhesive (Chemlok® 6108, manufactured by Rhode Co., Ltd.) was applied with a doctor blade as a vulcanizing adhesive layer and treated at 120°C for 4 minutes to form a 15 μm thick vulcanizing adhesive layer. Next, a phenol resin-based vulcanizing adhesive (Chemlok® 205, manufactured by Rhode Co., Ltd.) was applied on top of this with a doctor blade and treated at 120°C for 4 minutes to form a 10 μm thick primer layer consisting of a phenol resin layer. Subsequently, one protective layer (PET film) of the adhesive sheet obtained above was peeled off, and the exposed surface was bonded to the primer layer to obtain an adhesive sheet composed in the order of protective layer (PET film) / adhesive layer / primer layer / vulcanizing adhesive layer / protective layer (PET film).

[0086] <Examples 2-5 and Comparative Examples 1-7> An adhesive layer (adhesive sheet) was obtained in the same manner as in Example 1, except that the type, amount, and film thickness of the raw materials used in the production of the adhesive layer (adhesive sheet) were changed to those shown in Table 1. Furthermore, an adhesive sheet was obtained using this adhesive layer (adhesive sheet) in the same manner as in Example 1.

[0087] In Table 1, blank spaces indicate that a cell is not included. Chloroprene rubber used was Showa Denko K.K.'s Showa Denko AD. Epoxy resin (A) used was jER1256 from Mitsubishi Chemical Corporation, which is a bisphenol A type epoxy resin with a weight-average molecular weight Mw of 50,000. Epoxy resin (B) used was jER828 from Mitsubishi Chemical Corporation, which is a bisphenol A type epoxy resin with a weight-average molecular weight Mw of 370. Dicyandiamide used was DICY7 from Mitsubishi Chemical Corporation. 2-Methylimidazole used was 2MZ from Shikoku Chemicals, Inc. The acrylic adhesive used was SK Dyne 1604N from Soken Chemical Co., Ltd. The isocyanate compound used was L-45 from Soken Chemical Co., Ltd.

[0088] Furthermore, since the raw materials in Comparative Example 5 did not have adhesive properties, the resulting layer (sheet) was an adhesive layer (adhesive sheet) rather than a viscous adhesive layer (viscous adhesive sheet).

[0089] [Table 1]

[0090] <evaluation> (Ease of handling) From the adhesive sheets obtained in the examples and comparative examples, both PET films, which serve as the protective layer, were peeled off. The remaining adhesive layer / phenol resin layer / vulcanized adhesive layer, adhesive layer / vulcanized adhesive layer, phenol resin layer / vulcanized adhesive layer, or only the vulcanized adhesive layer was folded by hand. The condition at that time was evaluated according to the following criteria. The results are shown in "Handling" in Table 1. ○: No tearing occurs during PET film peeling, and it does not break when folded. ×: The PET film tore during peeling, or cracked when folded.

[0091] (Adhesive strength) Samples for evaluating adhesive strength were prepared using the compositions constituting the adhesive layers prepared in the examples and comparative examples. Specifically, each adhesive layer composition was applied to a 25 μm thick PET film using a doctor blade and treated at 80°C for 4 minutes to obtain a 20 μm thick coating. The release-treated side of a 38 μm thick PET film was then bonded to this coating to obtain a sample for evaluating adhesive strength.

[0092] The obtained samples for adhesion strength evaluation were cut into 25 mm widths to prepare test specimens. The release-treated PET film was peeled off the test specimens, and the exposed coating was attached to a stainless steel plate and pressed down using a 2 kg roller. Next, after standing for 20 minutes in a 23°C / 50%RH environment, one end of the test specimen was pulled at a tensile speed of 300 mm / min in a 180° direction relative to the adhesive surface, and the adhesive force required for peeling, i.e., the peel strength, was measured. The results are shown in "Adhesion Strength (N / 25 mm)" in Table 1.

[0093] Note that "Not Measurable" in Table 1 indicates that the obtained sample for adhesion strength evaluation had no adhesion whatsoever and therefore could not be measured. A value of 0.1 N / 25 mm or higher is considered good.

[0094] (Misalignment and overflow during vulcanization bonding, and adhesion after vulcanization bonding) The adhesive sheets obtained in the examples and comparative examples were cut to 12.5 mm x 25 mm. The PET film on the vulcanized adhesive layer side was peeled off, and the exposed surface was attached to a steel plate. Next, the other PET film was peeled off, and another steel plate was placed on top of the exposed surface and bonded together. Vulcanization bonding was performed by applying a load of 500 N for 10 minutes in a 160°C environment to prepare test specimens.

[0095] Subsequently, the samples were removed to a 23°C / 50%RH environment, and the misalignment of the iron plates and the degree of excess adhesive sheeting were visually observed and evaluated according to the following criteria. The results are shown in Table 1 under "Misalignment / Excessing". ○: No misalignment between the metal plates and no overflow of the adhesive sheet. △: There is slight misalignment between the metal plates or some excess adhesive sheeting, but this does not affect practical use. ×: There is misalignment between the metal plates or excess adhesive sheeting, which may cause practical problems.

[0096] Furthermore, the adhesive surfaces of the test specimens obtained above were pulled in the shear direction at a tensile speed of 10 mm / min, and the failure mode of the adhesive sheet was evaluated according to the following criteria. The results are shown in "Adhesion" in Table 1. This means that the higher the proportion of failure at the vulcanized adhesive layer / iron plate interface, the higher the adhesion at the adhesive layer / iron plate interface. ○: A large proportion of failures occur at the vulcanization adhesive layer / iron plate interface. ×: The proportion of failures occurring at the vulcanization adhesive layer / iron plate interface is small. -: No rating

[0097] From the results above, it was found that the adhesive sheet according to this embodiment has adhesive properties equivalent to conventional sheets, while also being superior in handling and adhesive strength, with less shifting and overflow during vulcanization bonding, resulting in excellent workability.

Claims

1. A method for manufacturing a rubber-metal joint in which unvulcanized rubber and metal are joined, A process for forming an unvulcanized rubber-metal laminate, in which the unvulcanized rubber, adhesive sheet, and metal are laminated in this order, and The process includes a vulcanization bonding step in which the unvulcanized rubber-metal laminate is heated and pressurized to bond the unvulcanized rubber and the metal to the adhesive sheet simultaneously. A method for producing a rubber-metal bond, wherein the adhesive sheet comprises, in order from the unvulcanized rubber side, a vulcanizing adhesive layer and a viscous adhesive layer, the vulcanizing adhesive layer comprising a halogenated polyolefin, and the viscous adhesive layer comprising a composition comprising 30 to 60% by mass of halogenated polyolefin, 30 to 60% by mass of resol-type phenolic resin, and 1 to 40% by mass of xylene resin.

2. The method for manufacturing a rubber-metal bond according to claim 1, wherein the adhesive sheet includes the vulcanizing adhesive layer in the outermost layer located on the unvulcanized rubber side, and the adhesive layer in the outermost layer located on the metal side.

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