JP7512686B2 - Rubber jointed body and method for manufacturing the same - Google Patents

Description

This disclosure relates to a rubber joint and a method for manufacturing a rubber joint.

Rubber joints having a base material such as plastic and a rubber-based resin layer have been known for some time. However, there have been cases where the adhesion between the base material and the rubber-based resin layer is insufficient, and they cannot be bonded by simply contacting each other.

Therefore, adhesives were used to bond the substrate and the rubber-based resin layer, but it was necessary to select an adhesive that would adhere to both the substrate and the rubber, or a combination of an adhesive and a primer. Since the surface adhesion and SP value of rubber vary depending on the compounding composition and vulcanization conditions, selecting an adhesive can take time. In addition, since the type of rubber selected varies depending on the required characteristics, it is necessary to develop an appropriate adhesive for bonding the substrates each time. Furthermore, the appropriate adhesive for the substrate also differs depending on the material. Therefore, selecting the optimal adhesive for bonding substrates such as plastic to the rubber-based resin layer had to be done by trial and error, which was very time-consuming.

Therefore, methods of vulcanizing and bonding a substrate to a rubber-based resin without using an adhesive, or methods of post-bonding a substrate to a vulcanized rubber-based resin without using an adhesive, have been considered. For example, Patent Document 1 discloses a rubber product in which a substrate having a substrate body and a vapor-deposited film is laminated with a rubber-based resin layer without using an adhesive. Patent Document 2 discloses a bonded body in which a substrate having a vapor-deposited film is bonded with silicone rubber without using an adhesive. Patent Document 3 discloses a vulcanized bonded body consisting of a polyamide-based resin member and a rubber member vulcanized and bonded to the polyamide-based resin member, in which a melamine derivative is contained in the rubber member.

JP 2015-166173 A International Publication No. 2017/122506 JP 2018-103496 A

As described above, methods of laminating a plastic substrate and a rubber-based resin without using an adhesive have been studied, as in Patent Document 1 and Patent Document 2, but the inventors have found that it may not be possible to obtain high adhesive strength with diene vulcanized rubber, which is a rubber other than silicone rubber. In addition, as in Patent Document 3, when a melamine derivative is contained in the rubber material, the physical properties of the rubber material may change.

This disclosure was made in consideration of the above problems, and aims to provide a rubber joint in which diene vulcanized rubber and a substrate are firmly joined without the use of adhesive, and a method for manufacturing the same.

One embodiment of the present disclosure provides a rubber joint having a substrate body, a substrate having a thin silica film formed on the substrate body, and a diene-based vulcanized rubber laminated on the thin silica film of the substrate, in which the diene-based vulcanized rubber and the substrate have a peel strength of 2.0 kgf/15 mm or more in a 180° peel test.

According to the present disclosure, a rubber joint can be obtained in which the diene vulcanized rubber and the substrate are firmly joined together without the use of adhesive.

One embodiment of the present disclosure provides a rubber joint having a substrate body, a substrate having a thin silica film formed on the substrate body, and a diene-based vulcanized rubber laminated on the thin silica film of the substrate, in which when the diene-based vulcanized rubber is peeled off from the substrate, peeling occurs due to material failure of the diene-based vulcanized rubber.

According to the present disclosure, a rubber joint is obtained in which delamination at the interface between the diene vulcanized rubber and the substrate is suppressed and the joint is firmly bonded.

One embodiment of the present disclosure provides a method for producing a rubber joint, comprising: a substrate preparation step of forming a thin silica film on a substrate body to prepare a substrate having the substrate body and the thin silica film; a coupling agent treatment step of treating the surface of the thin silica film of the substrate with a silane coupling agent having a functional group capable of crosslinking with a diene-based rubber component; and a vulcanization adhesion step of contacting the surface of the thin silica film of the substrate treated with the silane coupling agent with the surface of an unvulcanized diene-based rubber containing the diene-based rubber component, and vulcanization adhesion by heating and pressurization.

According to the present disclosure, it is possible to obtain a rubber joint in which diene vulcanized rubber and a substrate are firmly joined. In addition, since no adhesive is used, there is no need to select an adhesive, and a rubber joint can be easily obtained.

In addition, in the present disclosure, the silane coupling agent is preferably a sulfide-based silane coupling agent, since this ensures that a strongly bonded rubber joint can be obtained.

The rubber joint of the present disclosure has a strong bond between the substrate and the diene-based vulcanized rubber without the use of adhesive.

FIG. 2 is a schematic cross-sectional view illustrating a rubber joint body according to the present disclosure.

Below, an embodiment of the present disclosure will be described with reference to the drawings. However, the present disclosure can be implemented in many different forms, and should not be interpreted as being limited to the description of the embodiment exemplified below. In addition, in order to make the explanation clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those described above with respect to the previous figures are given the same reference numerals, and detailed explanations may be omitted as appropriate.

In this specification, when describing a mode in which another component is placed on a certain component, the term "above" or "below" is used, unless otherwise specified, to include both cases in which another component is placed directly above or below a certain component so as to be in contact with the component, and cases in which another component is placed above or below a certain component with another component interposed between them. In addition, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the term "on the surface side" or "on the surface" is used, unless otherwise specified, to include both cases in which another component is placed directly above or below a certain component so as to be in contact with the component, and cases in which another component is placed above or below a certain component with another component interposed between them.

As described above, conventional rubber joints in which a substrate and a diene-based vulcanized rubber are joined without using an adhesive may not have sufficient adhesive strength. The present inventors have discovered that by treating the surface of the silica thin film of a substrate having a silica thin film with a silane coupling agent having a functional group capable of crosslinking with a diene-based rubber component, it is possible to bond the silane coupling agent residue having the functional group to the silica thin film surface by a silane coupling reaction. Furthermore, they have discovered that by vulcanizing and bonding unvulcanized diene-based rubber and the silica thin film surface to which the silane coupling agent residue is bonded in a state of contact, a crosslinking reaction occurs between the functional group contained in the silane coupling agent residue and the diene-based rubber component, and have discovered that this results in a rubber joint in which the substrate and the diene-based vulcanized rubber are firmly joined by a covalent bond derived from the silane coupling agent.

The rubber joint and its manufacturing method disclosed herein are described in detail below.

A. Rubber joint (first embodiment)
The rubber joint body of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing an example of the rubber joint body of the present disclosure. As shown in Fig. 1, the rubber joint body 1 of the present disclosure has a substrate 2 having a substrate body 2a and a silica thin film 2b formed on the substrate body 2a, and a diene vulcanized rubber 3 laminated on the silica thin film 2b of the substrate 2, and the peel strength between the diene vulcanized rubber 3 and the substrate 2 in a 180° peel test is 2.0 kgf/15 mm or more.

I. Peel Strength The rubber joint body according to the present disclosure has a substrate and a diene-based vulcanized rubber laminated on the silica thin film of the substrate, and the surface of the silica thin film of the substrate and the surface of the diene-based vulcanized rubber are firmly bonded together by a covalent bond derived from the silane coupling agent, and therefore has high peel strength.

The peel strength between the diene vulcanized rubber and the substrate in a 180° peel test is preferably 5.0 kgf/15 mm or more. In this disclosure, the peel strength in a 180° peel test is a value measured by cutting the rubber joint to a width of 15 mm and using a tensile tester (Tensilon type tensile tester (model RTC-1310A, manufactured by Orientec Co., Ltd.)) in accordance with JIS K6854-2:1999 at a tensile speed of 50 mm/min. Specifically, the measurement method described in the examples can be adopted. In the case of rubber joints that are too small to be cut to a width of 15 mm, for example, if the width of the sealed portion is 6 mm or more, the length in the direction perpendicular to the width of the sealed portion is 3 mm or more, and a part of the rubber joint (product) can be fixed to the Tensilon other than the sealed portion, or 10 mm or more can be fixed with a jig (packing tape, etc.) that is attached to the rubber joint (product) and does not stretch or break, the peel strength can be measured and converted to the peel strength for a seal width of 15 mm to calculate the peel strength.

In the present embodiment, it is preferable that the rubber joint body is one in which peeling occurs due to material failure of the diene vulcanized rubber when the above-mentioned 180° peel test is performed.

II. Substrate The substrate in the present disclosure has a substrate body and a silica thin film formed on the substrate body.

(1) Substrate Body The substrate body in the present disclosure is not particularly limited as long as it can support a thin silica film, and examples thereof include resin films and molded resin products, woven and nonwoven fabrics of various fibers, metals, and the like.

Examples of resins contained in the resin film include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamide resins such as nylon 6 and nylon 66; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl acrylate; polystyrene, polycarbonate resins, polyarylate resins, polyimide resins, polyphenylene sulfide, and modified polyphenylene ether.
In particular, polyethylene terephthalate, nylon, polyimide, etc. are preferred from the viewpoint of having heat resistance that can withstand vulcanization adhesion. Polyethylene terephthalate is preferred because it is inexpensive. Polyimide is also preferred because it has higher heat resistance and allows product dimensions to be adjusted with high precision. In addition, polybutylene terephthalate and polyphenylene sulfide are also preferred in some cases to meet intermediate required specifications. The resin film may have a single layer structure or a multilayer structure in which multiple layers are laminated.

Resins contained in resin molded products include polyethylene terephthalate, polyamide, polycarbonate, modified polyphenylene ether, polyacetal, etc.

Examples of various fibers include inorganic fibers such as glass fibers, silica fibers, and carbon fibers, and synthetic resin fibers such as polyester fibers, acrylic fibers, vinylon fibers, nylon fibers, and polyolefin fibers.

Metals include metal ceramics such as gamma-alumina and alpha-alumina, aluminum for die casting, copper, and stainless steel. The substrate body in this disclosure may also be one that has been surface-treated with these metals.

(2) Silica thin film The silica thin film in the present disclosure is formed on the substrate body. When the substrate body is in the form of a film, the silica thin film may be formed on one or both of the main surfaces. When the substrate body has a plurality of surfaces, the silica thin film may be formed on one or more of the surfaces.
The silica thin film ( _SiOx ) in the present disclosure is preferably a vapor deposition film. Specific methods for producing the silica thin film include chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition, and physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating. In particular, it is preferable to form the silica thin film by the CVD method.

The film thickness of the thin film is usually preferably about 2 to 40 nm, more preferably 5 to 20 nm. The above-mentioned thin film can be measured by a stylus-type step measuring instrument such as Dektak. When the thin film is formed by multiple depositions, the thickness refers to the total thickness after multiple depositions.
Whether or not a thin silica film is disposed is not particularly limited, but can be determined, for example, by cutting the rubber joint body of the present disclosure in the direction in which the thin silica film is cut, observing the cross section with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), or by elemental analysis of a micro-portion of the thin film or analysis of Si—O bonds with micro-FT-IR.

III. Diene-based vulcanized rubber In the present disclosure, the diene-based vulcanized rubber is a rubber in which vulcanization (crosslinking reaction) occurs between the molecules of a diene-based rubber component having a double bond in the polymer main chain. In addition, in the present disclosure, the diene-based vulcanized rubber is preferably in a vulcanized state and in a state in which the degree of vulcanization required for the final product has been reached. Examples of the diene-based rubber component include rubber having a carbon-carbon double bond in the main chain and capable of being vulcanized. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), 1,2-polybutadiene (VBR), butyl rubber (IIR), halogenated butyl rubber (X-IIR), chloroprene rubber (CR), etc. These rubber components can be used alone or in combination of two or more types.

The rubber components constituting the diene vulcanized rubber in this disclosure may contain non-diene rubber components other than the diene rubber components. Examples of non-diene rubber components include silicone rubber. Of the total rubber components (100% by mass), the diene rubber components are preferably 80% by mass or more, and particularly preferably 100% by mass. Within the above range, the effect tends to be better obtained.

Diene-based vulcanized rubber is made by compounding the above-mentioned rubber material with various additives that are generally used in rubber compositions, such as vulcanizing agents, vulcanization accelerators, and fillers, which will be described later, and then kneading and vulcanizing the rubber in a conventional manner.

Diene vulcanized rubber is laminated onto the substrate by vulcanization adhesion. Vulcanization adhesion refers to bonding unvulcanized diene rubber to the substrate by vulcanizing the rubber.

IV. Silane coupling agent In the rubber joint in the present disclosure, the substrate and the diene vulcanized rubber are directly bonded without an adhesive layer. At the interface between the substrate and the diene vulcanized rubber, the covalent bond derived from the silane coupling agent described above exists, and the surface of the silica thin film of the substrate and the surface of the diene vulcanized rubber are firmly bonded via the covalent bond derived from the silane coupling agent. The covalent bond derived from the silane coupling agent has a siloxy group generated by the silane coupling reaction and a crosslinking group crosslinked to the diene rubber component. For example, the covalent bond derived from the sulfide-based silane coupling agent has a siloxy group bonded to the silica thin film surface and a (poly)sulfide group bonded to the diene vulcanized rubber surface. The (poly)sulfide group means to include "sulfide group" and "polysulfide group".

The silane coupling agent used in the present disclosure is a silane coupling agent having a functional group capable of crosslinking with a diene rubber component, and preferably contains a sulfur atom. For example, sulfide-based silane coupling agents and mercapto-based silane coupling agents are preferred. This is because these can be used for both sulfur vulcanization and peroxide vulcanization. In the case of peroxide vulcanization, reactive acrylic, epoxy, urethane, vinyl, and other silane coupling agents can be used.

Examples of sulfide-based silane coupling agents include bis-(3-(triethoxysilyl)-propyl)-disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(triethoxysilylpropyl)tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzothiazoletetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(tri 2-triethoxysilylpropyl) tetrasulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc.

In the present disclosure, it is particularly preferable to use a tetrasulfide-based silane coupling agent, since this allows for effective bonding with the diene-based vulcanized rubber by vulcanization.
In the present disclosure, it is particularly preferable to use bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(triethoxysilylpropyl)tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, and 3-triethoxysilylpropylbenzothiazole tetrasulfide.
In the present disclosure, the above silane coupling agents may be used alone or in combination of two or more.

V. Others The use of the rubber joint body of the present disclosure is not particularly limited, but may be any rubber product in which rubber is used at least in a wide range of fields such as medical, automotive, and aircraft. Specific examples include stoppers for vacuum blood collection tubes for medical use, and automobile tires.

The stopper for the vacuum blood collection tube may have the above-mentioned rubber joint as a piercing member, and may be fused or adhered to the open end of the blood collection container. The piercing member is pierced by a collection needle. In addition to the rubber joint, the stopper may include aluminum foil arranged on the base material side of the rubber joint, and a seal layer arranged on the surface of the aluminum foil opposite the rubber joint side, for fusion to the opening of the blood collection container. A printed layer containing acrylic resin or the like may also be included between the aluminum foil and the rubber joint.

When the rubber joint in the present disclosure is used as a stopper for a vacuum blood collection tube, the rubber component constituting the diene-based vulcanized rubber of the rubber joint is preferably isoprene rubber (IR). As the substrate body in the substrate, a resin film containing any of polyester resin, acrylic resin, polycarbonate resin, and polyamide resin is preferable.

When the rubber joint body of the present disclosure is used in tires such as automobile tires, examples of the rubber components constituting the diene-based vulcanized rubber of the rubber joint body include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butyl rubber (IIR), etc. Examples of the substrate body in the substrate include resin films containing nylon (polyamide), PET (polyester), and rayon (modified cellulose), woven fabrics of resin fibers, nonwoven fabrics, steel, cords of high carbon steel fibers, woven fabrics, nonwoven fabrics, etc.

When the rubber joint body of the present disclosure is used in tires such as automobile tires, examples of the substrate include components constituting tire cords such as carcasses, beads, belts, etc. Automobile tires, etc. are subject to large loads, shocks, etc., and therefore peeling between the components and the rubber may occur. For this reason, the rubber joint body of the present disclosure can be used preferably.

B. Rubber joint (second embodiment)
The rubber joined body of the second embodiment of the present disclosure is a rubber joined body having a substrate body, a substrate having a thin silica film formed on the substrate body, and a diene-based vulcanized rubber laminated on the thin silica film of the substrate, in which, when the diene-based vulcanized rubber is peeled off from the substrate, peeling occurs due to material failure of the diene-based vulcanized rubber.

I. Peel Strength The rubber joined body of this embodiment has a high adhesive strength at the interface between the substrate and the diene vulcanized rubber for the same reason as the rubber joined body of the first embodiment. Therefore, when peeling occurs, peeling does not occur at the interface between the substrate and the diene vulcanized rubber, but occurs due to material failure of the diene vulcanized rubber, which has a lower strength than the substrate.
Here, "when the diene vulcanized rubber and the substrate are peeled off" refers to any peeling method as long as the diene vulcanized rubber and the substrate are gripped and a force is applied in the direction of peeling, but does not include a method of applying any treatment to the interface between the two, such as a method of cutting the interface between the two with a knife or the like to peel them off.

The peeling method in the present disclosure may be, for example, the peeling method used in the 180° peel test of JIS K6854-2:1999 used in the first embodiment described above, and depending on the product size and shape, the 90° peel test of JIS K 6854-1:1999 may be used instead.
Also, the JIS K 6261 torsion test for rubber may be used instead, which tests for peeling between the substrate and rubber and rubber breakage due to torsion. In this case, it is preferable to adjust the length of the rubber to be short so that the rubber is not too long and twisted off in the middle. Peeling due to material failure of diene vulcanized rubber can be judged by microscopic observation of the peeled surface or FT-IR.

II. Others Other points such as materials in this embodiment are similar to those in the first embodiment, so the description thereof will be omitted here.

C. Manufacturing Method of Rubber Joint The manufacturing method of a rubber joint in the present disclosure includes a substrate preparation step of forming a thin silica film on a substrate body to prepare a substrate having the substrate body and the thin silica film, a coupling agent treatment step of treating a surface of the thin silica film of the substrate with a silane coupling agent having a functional group crosslinkable with a diene rubber component, and a vulcanization adhesion step of contacting the surface of the substrate on the thin silica film side treated with the silane coupling agent with a surface of an unvulcanized diene rubber containing the diene rubber component, and vulcanization adhesion by heating and pressurization.

The method for producing a rubber joint in the present disclosure makes it possible to obtain a rubber joint in which the diene vulcanized rubber and the substrate are firmly joined. In addition, since no adhesive is used, there is no need to select an adhesive, and a rubber joint can be easily obtained.

I. Substrate Preparation Step This step is a step of preparing a substrate having a substrate body and a silica thin film by forming a silica thin film on the substrate body. The substrate body is the same as that described in the above section "A. Rubber Joint (First Embodiment) II. Substrate (1) Substrate Body", and therefore the description here is omitted.

The silica thin film may be formed on at least one surface of the substrate body. If the substrate body is in the form of a film, it may be formed on one or both main surfaces. If the substrate body has multiple surfaces, it may be formed on one or more surfaces. The silica thin film and the method for forming it are the same as those described in "A. Rubber joint (first embodiment) II. Substrate (2) Silica thin film", so the description here is omitted.

II. Coupling agent treatment step This step is a step of treating the surface of the silica thin film of the substrate with a silane coupling agent having a functional group capable of crosslinking with a diene rubber component. As the silane coupling agent, the same one as described in the above section "A. Rubber joint (first embodiment) IV. Silane coupling agent" can be used. The silane coupling agent in this disclosure has a hydrolyzable group (a group that can form a silanol group by hydrolysis) such as an alkoxy group bonded to the central silicon atom, so it is hydrolyzed and undergoes a dehydration condensation reaction with the silanol group (SiOH group) on the surface of the silica thin film. This treatment allows the silane coupling agent residue having a functional group capable of crosslinking with a diene rubber component to be bonded to the surface of the silica thin film.

The treatment method with the silane coupling agent may be a wet coating method or a dry coating method.
In the case of wet coating, the coupling agent is diluted with water or a water-solvent mixture and then applied. Among them, the dip (immersion coating) method in which the substrate is immersed in the solution is preferred. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, esters such as isopropyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and alcohols such as methanol and ethanol. These may be used alone or in combination of two or more. Among them, it is preferable to use alcohols such as ethanol. After immersion, it is preferable to wash and dry. In addition to the above coupling agent, the treatment with the silane coupling agent may use an acid or basic compound as a catalyst as necessary, such as acetic acid, hydrochloric acid, nitric acid, sulfuric acid, and aqueous ammonia.

The dry coating method is a method of directly applying a coupling agent in a vacuum or reduced pressure environment, and is selected from methods such as PVD, CVD deposition, and reduced pressure spray, in which a silane coupling agent is applied to a substrate in a molten state in the gas phase. In particular, for thermal CVD deposition, it is preferable to perform dry coating by volatilization from the silane coupling agent volatilization chamber of a thermal CVD device provided by Komeric for parylene coating, or from a thermal CVD chamber of parylene dimer.

Before being treated with a silane coupling agent, the surface of the thin silica film of the substrate in this disclosure has a contact angle of pure water of, for example, 10° to 40°, and preferably 20° to 30°, when the substrate body is PET or polyimide. For polyamide (nylon), the contact angle is 0° to 35°, and preferably 10° to 25°.

On the other hand, after treatment with a silane coupling agent, the surface of the substrate on the silica thin film side treated with the silane coupling agent has a contact angle of pure water of 50° to 90°, preferably 60° to 80°, for example, when the substrate body is PET or polyimide, and 30° to 80°, preferably 40° to 70°, for polyamide (nylon).
In the present disclosure, the contact angle of pure water is a value measured by the θ/2 method in accordance with JIS R3257.

III. Vulcanization adhesion step This step is a step of bringing the surface of the substrate treated with the silane coupling agent on the silica thin film side into contact with the surface of the unvulcanized diene rubber containing the diene rubber component, and vulcanizing and adhering the two together by heating and pressurizing.

The unvulcanized diene rubber contains at least the diene rubber component and vulcanizing agent described in "A. Rubber Joint (First Embodiment) III. Diene Vulcanized Rubber" above, and may contain optional components such as fillers, vulcanization accelerators, vulcanization aids, antioxidants, and softeners. In this disclosure, the diene vulcanized rubber refers to a vulcanized product of diene rubber.

Examples of vulcanizing agents include sulfur (powdered sulfur, precipitated sulfur, insoluble sulfur), sulfur-containing compounds such as alkylphenol disulfides, and organic peroxides such as dicumyl peroxide. These may be used alone or in combination of two or more.

Examples of vulcanization accelerators include thiuram-based, sulfenamide-based, guanidine-based, thiazole-based, aldehyde ammonia-based, aldehyde amine-based, and thiourea-based vulcanization accelerators. These may be used alone or in combination of two or more.

Examples of fillers include silica, carbon black, calcium carbonate, talc, kaolin, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. These may be used alone or in combination of two or more.

The unvulcanized diene rubber can be prepared by kneading the above diene rubber components, vulcanizing agent, and additives in a commonly used mixer such as a Banbury mixer, kneader, or roll according to a conventional method.

In this process, the unvulcanized diene rubber is brought into contact with the surface of the silica thin film side of the substrate treated with a silane coupling agent, and in this state, heated and pressurized to vulcanize and bond them together. For example, the unvulcanized diene rubber is compounded with the substrate so that it is in contact with the surface of the silica thin film side of the substrate, and the compound is heated and pressed, allowing vulcanization bonding and vulcanization molding to be carried out simultaneously. This method can simplify the manufacturing process of the rubber joint.

After the above coupling agent treatment process, the surface of the substrate on the silica thin film side has a silane coupling agent residue that has a functional group (such as a (poly)sulfide group) that can crosslink with the diene rubber component bonded to it. Therefore, when the unvulcanized diene rubber is vulcanized to become a diene vulcanized rubber (vulcanizate), the crosslinkable functional group contained in the silane coupling agent residue bonded to the surface of the substrate on the silica thin film side crosslinks with the diene rubber component. Therefore, the substrate and the diene vulcanized rubber are firmly bonded together by a covalent bond derived from the silane coupling agent.

The vulcanization conditions may be a temperature within the range of, for example, 110 to 185°C, preferably 125 to 170°C, a pressure within the range of, for example, 2 to 200 kg/ ^cm2 , preferably 10 to 70 kg/ ^cm2 , and a heating and pressing time within the range of, for example, 1 to 120 minutes.
In this step, the unvulcanized diene rubber and the substrate may be placed in a metal mold and heated and pressurized to perform molding and vulcanization at the same time.
After the vulcanization and bonding process, the vulcanized and molded rubber bonded body is removed from the mold, and burrs and the like are removed to produce the final product.

D. Others The above-mentioned surface treatment with the silane coupling agent can also be applied to the case where the substrate body is silicone rubber. In this case, the silane coupling agent residue having a functional group capable of crosslinking with a diene rubber component can be directly bonded to the silicone rubber without forming a silica thin film on the silicone rubber.

That is, by carrying out a coupling agent treatment process in which the surface of the silicone rubber is treated with a silane coupling agent having a functional group capable of crosslinking with a diene rubber component, and a vulcanization adhesion process in which the surface of the silicone rubber treated with the silane coupling agent is brought into contact with the surface of an unvulcanized diene rubber containing a diene rubber component and vulcanized and bonded by heating and pressurization, a rubber joint body in which the silicone rubber and the non-silicone diene rubber are firmly bonded can be produced. Note that it is preferable to perform a plasma treatment on the silicone rubber surface before the silane coupling agent treatment process.

In this case, the rubber joint has silicone rubber and diene vulcanized rubber laminated on the silicone rubber, and the peel strength between the diene vulcanized rubber and the silicone rubber in a 180° peel test is 2.0 kgf/15 mm or more.

In this case, the rubber joint has silicone rubber and diene vulcanized rubber laminated on the silicone rubber, and when a 180° peel test is performed between the diene vulcanized rubber and the silicone rubber, peeling occurs due to material failure of the silicone rubber, resulting in a rubber joint.

This disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical ideas described in the claims of this disclosure and provides similar effects is included within the technical scope of this disclosure.

The following examples and comparative examples will explain this disclosure in more detail.

Example 1
A silica vapor deposition film was formed on one surface of a 12 μm thick PET film by CVD to prepare a substrate (substrate A). Next, sulfide silane was bonded to the surface of the silica vapor deposition film of the substrate by the following method. First, 30 mL of ethanol (Junsei Chemical), 1.8 mL of 28% ammonia water (Kanto Chemical), and 0.6 mL of bis(triethoxysilylpropyl)tetrasulfide (Tokyo Chemical Industry Co., Ltd.) were mixed, and the entire amount was transferred to a glass dish. The substrate A (100 mm x 100 mm) was immersed in this mixed solution and left to stand for 30 minutes, then thoroughly washed with ethanol and naturally dried. This operation resulted in a substrate to which sulfide silane was bonded.

The static water contact angle (θ/2 method) of the silica vapor deposition film surface of the substrate to which this sulfide silane was bonded was measured and found to be 78.8°. Note that the static water contact angle (θ/2 method) of the silica vapor deposition film surface of the substrate before the sulfide silane was bonded was 23.5°.

On the surface of the silica vapor deposition film of the substrate to which sulfide silane was bonded, unvulcanized isoprene rubber with a thickness of 2 mm (manufactured by Kokoku Intec Co., Ltd.) was heated and pressed in a 100 mm square press mold on the substrate at a press temperature of 155°C, a press time of 10 minutes, and a press pressure of 30 kg/ ^cm2 to vulcanize and bond the substrate and isoprene rubber, producing a rubber joint 1. At this time, in order to measure the peel strength of the rubber joint, a 50 mm x 100 mm PTFE film was placed on half of the surface of the silica vapor deposition film of the substrate to which sulfide silane was bonded, and the unvulcanized isoprene rubber was vulcanized and bonded.

This rubber bonded body was cut into 15 mm widths to prepare test pieces. The peel strength between the substrate and isoprene rubber for four test pieces was measured in accordance with JIS K6854-2:1999 using a Tensilon tensile tester (model RTC-1310A, manufactured by Orientec Co., Ltd.). The 50 mm substrate and isoprene rubber portion, excluding the PTFE film, were each held by the gripping tools of the tensile tester, and a 180° peel test was carried out at a peel speed of 50 mm/min to measure the peel strength between the substrate and isoprene rubber. The results are shown in Table 1. When the condition after peeling was checked, it was confirmed that peeling was due to material failure of the isoprene rubber, not interfacial peeling.

(Examples 2 and 3)
Rubber joint bodies 2 and 3 were produced and their peel strengths were measured in the same manner as in Example 1, except that a nylon film (substrate B) (manufactured by Dai Nippon Printing Co., Ltd.) with a thickness of 16 μm that had been silica-deposited by CVD under the same conditions as those for producing substrate A in Example 1 and a polyimide film (substrate C) (manufactured by Dai Nippon Printing Co., Ltd.) with a thickness of 25 μm that had been silica-deposited by CVD under the same conditions as those for producing substrate A in Example 1 were prepared as substrates. When the state after peeling was checked, it was confirmed that peeling was due to material failure of the isoprene rubber, not interfacial peeling.

(Comparative Example 1)
Substrate A was used and, instead of the sulfide silane treatment, a methacryloxypropyltrimethoxysilane (A-174, manufactured by Merck) treatment was carried out by dry coating. First, substrate A was set in a sample chamber of a reduced pressure deposition apparatus (manufactured by Komeric) equipped with a silane treatment chamber, and Ar plasma treatment was carried out at 2 mbar for 30 seconds, and methacryloxypropyltrimethoxysilane (A-174, manufactured by Merck) treatment was carried out at 0.3 mbar for 1200 seconds.

Next, as in Example 1, unvulcanized isoprene rubber was placed on a substrate treated with methacryloxypropyltrimethoxysilane in a 100 mm square press mold and heated and pressurized under the same conditions as in Example 1 to vulcanize and bond the substrate and isoprene rubber, producing a rubber bonded body 4, and measuring the peel strength. When the state after peeling was checked, it was confirmed that peeling had occurred at the interface between the substrate and the isoprene rubber.

(Comparative Example 2)
Using the substrate A, unvulcanized isoprene rubber was heated and pressed on the substrate in a 100 mm square press mold under the same conditions as in Example 1 without surface treatment with a sulfide silane coupling agent to vulcanize and bond the substrate and isoprene rubber to produce a rubber bonded body 5, and the peel strength was measured. When the state after peeling was checked, it was confirmed that peeling occurred at the interface between the substrate and the isoprene rubber.

(Reference example)
A 0.1 mm silicone rubber sheet (Keiju, manufactured by Mitsubishi Chemical) was subjected to wet treatment with sulfide silane. The silicone rubber sheet was treated for 120 seconds in a vacuum _O2 plasma device (manufactured by Yamato Scientific Co., Ltd.), and the silicone rubber sheet (100 x 100 mm) was immediately immersed in a mixed solution prepared in the same manner as in Example 1. After leaving the silicone rubber sheet to stand for 30 minutes, the silicone rubber sheet was thoroughly washed with ethanol and allowed to dry naturally. This operation resulted in a silicone rubber sheet to which sulfide silane was bonded. The static water contact angle (θ/2 method) of this silicone sheet was measured to be 75.4°. The static water contact angle (θ/2 method) immediately before the sulfide was bonded was 41.2°.

When unvulcanized isoprene rubber was placed on top of a sulfide silane-treated silicone rubber sheet in a press mold and heated and pressurized in the same manner as in Example 1 to vulcanize and bond the two rubbers, the two rubbers bonded together, but in a 180° peel test the silicone rubber broke at its roots, causing the rubber to break.

The surface of the 12 μm thick PET film (manufactured by Dai Nippon Printing Co., Ltd.) on the side opposite to the deposition film side of the CVD silica deposition film was coated with a laminating agent consisting of Seikabond base agent E-372 (17 parts by weight: manufactured by Dainichi Seika Chemicals Co., Ltd.), Seikabond hardener C-84 (3 parts by weight) and ethyl acetate (80 parts by weight) using wire bar No. 5, dried with a dryer, and laminated with a 30 μm thick hard aluminum foil (manufactured by Mitsubishi Aluminum Co., Ltd.) to prepare a CVD silica deposition film for adhesion confirmation. The silica deposition surface of the CVD silica deposition film and the silicone rubber side surface of the isoprene rubber and silicone rubber laminated sheet were treated in a vacuum _O2 plasma device (manufactured by Yamato Scientific Co., Ltd.) under 0.5 mbar for 30 seconds and 120 seconds, respectively, and the treated surfaces were placed in close contact with each other under a weight (weight of about 10 g/ ^m2 ) and left for 8 hours. After 8 hours, the contact parts of the silica deposition film and the laminated rubber sheet were firmly bonded. When the unbonded portions were left on the film and rubber sheet and peeled off at 180° with a Tensilon, there was no interfacial peeling, but the rubber broke at the silicone rubber and peeled off.

In the peel test, the rubber joints produced in Examples 1 to 3 had high peel strength, and did not peel at the interface between the substrate and diene-based vulcanized rubber, but peeling occurred due to material failure of the diene-based vulcanized rubber. The rubber joints produced in Comparative Examples 1 and 2 had low peel strength, and all were in a temporary bonded state and peeled at the interface. In the Reference Example, the PET film and isoprene rubber, a non-silicone rubber, were firmly bonded via a silicone rubber sheet.

1 ... rubber bonded body 2 ... substrate 3 ... diene vulcanized rubber

Claims (3)

A substrate having a substrate body and a silica thin film formed on the substrate body;
a diene-based vulcanized rubber laminated on the silica thin film of the substrate,
a covalent bond derived from a sulfide-based silane coupling agent is present at the interface between the substrate and the diene-based vulcanized rubber,
the substrate is at least one resin selected from the group consisting of polyester resin, polyamide resin, acrylic resin, polystyrene, polycarbonate resin, polyarylate resin, polyimide resin, polyphenylene sulfide, and modified polyphenylene ether;
A rubber joint, in which the diene vulcanized rubber and the substrate have a peel strength of 2.0 kgf/15 mm or more in a 180° peel test. A substrate having a substrate body and a silica thin film formed on the substrate body;
a diene-based vulcanized rubber laminated on the silica thin film of the substrate,
a covalent bond derived from a sulfide-based silane coupling agent is present at the interface between the substrate and the diene-based vulcanized rubber,
the substrate is at least one resin selected from the group consisting of polyester resin, polyamide resin, acrylic resin, polystyrene, polycarbonate resin, polyarylate resin, polyimide resin, polyphenylene sulfide, and modified polyphenylene ether;
A rubber joint, in which, when the diene vulcanized rubber is peeled off from the substrate, peeling occurs due to material failure of the diene vulcanized rubber. a substrate preparation step of forming a silica thin film on a substrate body to prepare a substrate having the substrate body and the silica thin film;
a coupling agent treatment step of treating a surface of the silica thin film of the substrate with a silane coupling agent having a functional group capable of crosslinking with a diene rubber component;
a vulcanization adhesion process for vulcanizing and adhering a surface of the substrate treated with the silane coupling agent on the side of the silica thin film to a surface of an unvulcanized diene rubber containing a diene rubber component, by contacting the surface and applying heat and pressure to the unvulcanized diene rubber,
the substrate is at least one resin selected from the group consisting of polyester resin, polyamide resin, acrylic resin, polystyrene, polycarbonate resin, polyarylate resin, polyimide resin, polyphenylene sulfide, and modified polyphenylene ether;
The method for producing a rubber joint body, wherein the silane coupling agent is a sulfide-based silane coupling agent .

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