Adhesive composition for vulcanized rubber, and tires

Abstract

To provide an adhesive composition for a vulcanized rubber which is excellent in adhesiveness.SOLUTION: The adhesive composition for a vulcanized rubber contains: at least one rubber selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene rubber and polybutadiene; a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator; and an organic solvent. The rubber has a weight average molecular weight of 200,000 or more. The concentration of the rubber is 3.0-10 mass% in the total amount of the composition. The content of the dithiocarbamate-based vulcanization accelerator or the morpholine-based vulcanization accelerator is 2.0-10 pts.mass based on 100 pts.mass of the rubber. There is also provided a tire in which a vulcanized tire and a component are bonded with the adhesive composition for a vulcanized rubber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition for vulcanized rubber and a tire.

Background Art

[0002] Conventionally, an inner liner layer mainly composed of a low gas permeability butyl rubber has been provided on the inner surface of a pneumatic tire to prevent air leakage and maintain a constant tire air pressure. As one of the methods for thinning the inner liner layer, an adhesive containing a halogenated butyl rubber or the like is disposed between a butyl rubber sheet and another film, and then vulcanized to integrate the butyl rubber sheet and the other film (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, there is a system that uses IoT (Internet of Things) to monitor information (for example, air pressure, etc.) of tires mounted on automobiles. In the above system, a tire has a container (container) inside that houses devices such as a sensor (detector) for monitoring tire information. Usually, the above container is fixed to the tire (for example, inner liner) with an adhesive. Under such circumstances, the inventors of the present invention prepared an adhesive composition referring to Patent Document 1, applied the adhesive composition to the surface of a vulcanized inner liner, and adhered a part (for example, a rubber container that houses a sensor). As a result, it became clear that the adhesiveness between the adhesive composition and the vulcanized rubber (the above inner liner and / or container) was not always sufficient.

[0005] Therefore, in view of the above circumstances, the present invention aims to provide an adhesive composition for vulcanized rubber that exhibits excellent adhesion. Furthermore, the present invention also aims to provide a tire in which parts are bonded together. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the present inventors have found that the desired effect can be obtained by an adhesive composition containing a specific rubber, a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator, and an organic solvent, where the weight-average molecular weight of the rubber, the concentration of the rubber, and the content of the vulcanization accelerator are all within specific ranges, leading to the present invention. The present invention is based on the above findings, and specifically solves the above problems with the following configuration.

[0007] [1] It contains at least one rubber selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene rubber, and polybutadiene, a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator, and an organic solvent. The weight-average molecular weight of the above rubber is 200,000 or more. The concentration of the above rubber is 3.0 to 10% by mass of the total amount of the composition. A vulcanizing rubber adhesive composition wherein the content of the above-mentioned dithiocarbamate-based vulcanization accelerator or the above-mentioned morpholine-based vulcanization accelerator is 2.0 to 10 parts by mass per 100 parts by mass of the above-mentioned rubber. [2] The vulcanizing rubber adhesive composition according to [1], wherein the above organic solvent comprises at least one selected from the group consisting of toluene, xylene, cyclohexane, and n-hexane. [3] The adhesive composition for vulcanized rubber according to [1] or [2], wherein the rubber comprises styrene-butadiene rubber and / or polybutadiene. [4] A vulcanizing rubber adhesive composition according to any one of [1] to [3], which is substantially free of sulfur. [5] A tire in which a vulcanized tire and a component are bonded together with a vulcanized rubber adhesive composition described in any of [1] to [4]. [6] The above component is a rubber container that houses a sensor, as described in [5]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an adhesive composition for vulcanized rubber that exhibits excellent adhesion. Furthermore, the present invention can also provide a tire with parts bonded together. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, unless otherwise specified, each component may be composed of the substance corresponding to that component, either individually or in combination of two or more substances. If a component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, unless otherwise specified, there are no particular restrictions on the method of manufacture of each component. For example, conventionally known methods may be used. In this specification, superior adhesion is sometimes referred to as superior effects of the present invention.

[0010] [Adhesive composition for vulcanized rubber] The adhesive composition for vulcanized rubber of the present invention (the adhesive composition of the present invention) is It contains at least one rubber selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene rubber, and polybutadiene, a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator, and an organic solvent. The weight average molecular weight of the above rubber is 200,000 or more, the concentration of the above rubber is 3.0 to 10% by mass in the total amount of the composition, and the content of the above dithiocarbamate vulcanization accelerator or the above morpholine vulcanization accelerator is 2.0 to 10 parts by mass with respect to 100 parts by mass of the above rubber, which is an adhesive composition for vulcanized rubber. Hereinafter, each component contained in the adhesive composition of the present invention will be described in detail.

[0011] [Rubber] The adhesive composition of the present invention contains at least one rubber selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene rubber, and polybutadiene. The above at least one rubber may be hereinafter referred to as "specific rubber" in some cases.

[0012] [Weight average molecular weight of rubber] In the present invention, the weight average molecular weight of the above specific rubber is 200,000 or more. From the viewpoint that the effects of the present invention are more excellent, the weight average molecular weight of the above specific rubber is preferably 300,000 or more. The upper limit of the weight average molecular weight of the above specific rubber is not particularly limited, and it may be 2,000,000 or less.

[0013] In the present invention, the weight average molecular weight of the specific rubber is a standard polystyrene conversion value obtained by gel permeation chromatography (GPC) measurement under the following conditions. · Solvent: Tetrahydrofuran · Detector: RI detector

[0014] [Various rubbers] Natural rubber, polyisoprene, styrene-butadiene rubber, and polybutadiene that can be used as the specific rubber in the present invention are not particularly limited other than the above weight average molecular weight. For example, conventionally known ones can be mentioned.

[0015] From the viewpoint of having superior effects and drying properties, the specified rubber described above preferably contains styrene-butadiene rubber and / or polybutadiene, and more preferably contains styrene-butadiene rubber.

[0016] [Concentration of specific rubbers] In the present invention, the concentration of the specified rubber is 3.0 to 10% by mass of the total amount of the adhesive composition of the present invention. From the viewpoint of achieving superior effects and drying properties, the concentration of the specified rubber described above is preferably 4.0 to 8.0% by mass of the total amount of the adhesive composition of the present invention.

[0017] (Other types of rubber) The adhesive composition of the present invention preferably does not contain rubber other than the specified rubber described above (other rubber), but it may further contain other rubber. If the adhesive composition of the present invention further contains other rubbers, it is preferable that the content of the above-mentioned specific rubber in the total amount of rubber exceeds 50% by mass, and more preferably 80% by mass or more.

[0018] [Vulcanization accelerator] The adhesive composition of the present invention contains a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator. Dithiocarbamate-based vulcanization accelerators or morpholine-based vulcanization accelerators are highly active and can crosslink or vulcanize the adhesive composition of the present invention even if the adhesive composition of the present invention does not contain sulfur, which is commonly used as a vulcanizing agent in rubber compositions. Therefore, the adhesive composition of the present invention exhibits excellent adhesive properties.

[0019] From the viewpoint of achieving superior effects of the present invention, the adhesive composition of the present invention preferably contains a dithiocarbamate-based vulcanization accelerator.

[0020] [Dithiocarbamate-based vulcanization accelerators] Dithiocarbamate-based vulcanization accelerators are compounds having a group represented by the following formula (1). [ka] (1)

[0021] In formula (1), R and R' each independently represent a hydrocarbon group.

[0022] Examples of dithiocarbamate-based vulcanization accelerators include compounds represented by the following formula (2). [ka] (2)

[0023] In formula (2), R and R' each independently represent a hydrocarbon group. X represents metal, n represents 1 through 3. Examples of hydrocarbon groups include aliphatic hydrocarbon groups such as alkyl groups and aromatic hydrocarbon groups such as phenyl groups. Examples of the above metals include zinc, tellurium, iron, and copper.

[0024] Examples of dithiocarbamate-based vulcanization accelerators include copper dimethyldithiocarbamate, tellurium diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dimethyldithiocarbamate. In particular, from the viewpoint of achieving superior effects of the present invention, the dithiocarbamate-based vulcanization accelerator preferably includes a dithiocarbamate-based vulcanization accelerator containing zinc. It is more preferable to include at least one selected from the group consisting of zinc N-ethyl-N-phenyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dimethyldithiocarbamate.

[0025] [Morpholine-based vulcanization accelerator] Morpholine-based vulcanization accelerators are compounds that contain a morpholine ring. Examples of morpholine-based vulcanization accelerators include 4,4′-dithiodimorpholine and 2(4-morpholinodithio)benzimidazole. In particular, from the viewpoint of achieving superior effects of the present invention, the morpholine-based vulcanization accelerator is preferably a compound in which two morpholine rings are linked via a polysulfide bond, and more preferably a compound that includes 4,4′-dithiodimorpholine.

[0026] [Content of vulcanization accelerator] In the present invention, the content of the dithiocarbamate-based vulcanization accelerator or the morpholine-based vulcanization accelerator is 2.0 to 10 parts by mass per 100 parts by mass of the specified rubber. From the viewpoint of achieving superior effects of the present invention and improving the fluidity of the composition, the content of the dithiocarbamate-based vulcanization accelerator is preferably 3.0 to 8.0 parts by mass per 100 parts by mass of the specified rubber. From the viewpoint of achieving superior effects of the present invention and improving the fluidity of the composition, the content of the morpholine-based vulcanization accelerator is preferably 2.0 to 8.0 parts by mass per 100 parts by mass of the specified rubber.

[0027] When using a dithiocarbamate-based vulcanization accelerator and a morpholine-based vulcanization accelerator in combination, it is preferable that the total amount of both be 2.0 to 10 parts by mass per 100 parts by mass of the specified rubber.

[0028] [organic solvent] The adhesive composition of the present invention contains an organic solvent. The above organic solvent is not particularly limited as long as it is inert to the above-mentioned specific rubber and the above-mentioned vulcanization accelerator and can dissolve both.

[0029] From the viewpoint of providing superior effects of the present invention, as well as excellent drying properties and environmental friendliness, the organic solvent preferably contains at least one selected from the group consisting of toluene, xylene, cyclohexane, and n-hexane, and more preferably contains cyclohexane.

[0030] (optional ingredient) The adhesive composition of the present invention may further contain components other than those described above (optional components). Examples of optional components include plasticizers, fillers, balloons (hollow bodies), silane coupling agents, anti-aging agents, antioxidants, solvents, and thixotropic agents.

[0031] (sulfur) One preferred embodiment of the adhesive composition of the present invention is that it is substantially free of sulfur. The sulfur refers to a substance consisting solely of sulfur, which is commonly used as a vulcanizing agent in rubber compositions. The sulfur does not include sulfur-containing compounds such as dithiocarbamate-based vulcanization accelerators. The fact that the adhesive composition of the present invention is substantially sulfur-free means that the amount of sulfur is 0 to 0.1 parts by mass per 100 parts by mass of the total amount of rubber components contained in the adhesive composition of the present invention.

[0032] (water) One preferred embodiment of the adhesive composition of the present invention is that it substantially contains no water, from the viewpoint of having superior effects, drying properties, and environmental friendliness. The fact that the adhesive composition of the present invention is substantially water-free means that the amount of water is 0 to 1.0% by mass of the total amount of the adhesive composition of the present invention.

[0033] [Manufacturing method] The method for producing the adhesive composition of the present invention is not particularly limited. For example, it may involve mixing the components described above.

[0034] [Application] The adhesive composition of the present invention is useful as an adhesive for fixing other materials (e.g., rubber containers for housing equipment) to vulcanized rubber (e.g., tires (especially inner liners)).

[0035] [How to use] The adhesive composition of the present invention can be cured, for example, under conditions of 5 to 40°C. When curing the adhesive composition of the present invention, it is not necessary to heat the adhesive composition. The adhesive composition of the present invention can be used by applying the adhesive composition to vulcanized rubber and / or other materials, allowing the adhesive composition to dry for 3 to 30 minutes under conditions of, for example, 10 to 40°C, then bonding the two materials together, and allowing the adhesive composition to harden and bond the two materials together by, for example, leaving them under conditions of room temperature (e.g., 5 to 40°C).

[0036] [tire] The tire of the present invention is a tire in which a vulcanized tire and a component are bonded together with the vulcanized rubber adhesive composition of the present invention.

[0037] [Vulcanized tires] The vulcanized tire used in the tire of the present invention is not particularly limited as long as it is a vulcanized (pre-vulcanized) tire. [Adhesive composition] The adhesive composition used in the tire of the present invention is not particularly limited as long as it is the adhesive composition for vulcanized rubber of the present invention.

[0038] 〔parts〕 Examples of components used in the tire of the present invention include a rubber container that incorporates a sensor. (container) The container (exterior) described above is made of rubber. Preferably, the rubber forming the container is vulcanized. The rubber used to form the above container is not particularly limited. Preferably, the rubber used to form the above container contains natural rubber as a rubber component. (sensor) The sensors to be built into the above container are not particularly limited. Examples include sensors intended to acquire information such as tire pressure, tire wear, and road surface conditions.

[0039] One preferred embodiment of the above container is that it is bonded to, for example, the inner liner of a tire. [Examples]

[0040] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

[0041] [Manufacturing of adhesive compositions] Each adhesive composition was prepared by using the components shown in Table 1 in the proportions (parts by mass) indicated in the same table and mixing them in a stirrer.

[0042] [evaluation] The following evaluations were performed using each adhesive composition manufactured as described above. The results are shown in the respective tables.

[0043] [Adhesiveness] The adhesive properties (adhesion to vulcanized rubber) were evaluated using each adhesive composition manufactured as described above.

[0044] To evaluate the adhesive properties of vulcanized rubber, vulcanized rubbers 1 and 2 were first prepared as follows. Preparation of vulcanized rubber 1 From the components listed in the following "Rubber Composition for Vulcanizing Rubber 1," all components except sulfur and vulcanization accelerator were kneaded in a 1.8 L sealed mixer for 5 minutes and released to obtain a masterbatch. Sulfur and vulcanization accelerator were added to the obtained masterbatch and mixed in an open roll to prepare the rubber composition for vulcanizing rubber 1. Using the rubber composition for vulcanized rubber 1 prepared as described above, vulcanized rubber 1 (25 mm wide, 10 cm long, 2 mm thick) was produced by vulcanizing it in a mold of a predetermined shape at 170°C for 10 minutes.

[0045] ((Rubber composition for vulcanized rubber 1)) • 100 parts by mass of halogenated butyl rubber (brominated isobutylene isoprene rubber, manufactured by Exxon Chemical) • 25 parts by mass of carbon black (35m³ of Nitelon #GN and N2SA manufactured by Shin-Nippon Carbon Co., Ltd.) 2 / g • 3 parts by mass of zinc oxide (Type 3 zinc oxide manufactured by Seido Chemical Industry Co., Ltd.) • 3 parts by mass of sulfur (Sulfax 5, manufactured by Tsurumi Chemical Industries, Ltd.) • 2 parts by mass of vulcanization accelerator (DM-PO manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0046] Preparation of vulcanized rubber 2 From the components listed in the following "Rubber Composition for Vulcanized Rubber 2," all components except sulfur and vulcanization accelerator were kneaded in a 1.8 L sealed mixer for 5 minutes and released to obtain a masterbatch. Sulfur and vulcanization accelerator were added to the obtained masterbatch and mixed in an open roll to prepare the rubber composition for vulcanized rubber 2. Using the rubber composition for vulcanized rubber 2 prepared as described above, vulcanized rubber 2 (25 mm wide, 10 cm long, 2 mm thick) was produced by vulcanizing it in a mold of a predetermined shape at 170°C for 10 minutes.

[0047] ((Rubber composition for vulcanized rubber 2)) • 100 parts by mass of natural rubber • 25 parts by mass of carbon black (35m³ of Nitelon #GN and N2SA manufactured by Shin-Nippon Carbon Co., Ltd.) 2 / g • 3 parts by mass of zinc oxide (Type 3 zinc oxide manufactured by Seido Chemical Industry Co., Ltd.) • 3 parts by mass of sulfur (Sulfax 5, manufactured by Tsurumi Chemical Industries, Ltd.) • 2 parts by mass of vulcanization accelerator (DM-PO manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0048] • Preparation of test specimens ·Applicable process Each adhesive composition manufactured as described above is applied to the vulcanized rubber 1 (application amount: 2-5 g / cm²). 2 The adhesive composition was dried for 10 minutes under 25°C conditions, and then bonded with the vulcanized rubber 2 to obtain a laminate.

[0049] ·Curing process Each laminate obtained as described above was cured for 10 minutes under conditions of 25°C and 50% relative humidity to obtain a test specimen having an adhesive layer (1 mm thick) of adhesive composition between vulcanized rubber 1 and 2.

[0050] • Tensile test Using the test specimens obtained as described above, the peel adhesion strength was measured under conditions of 25°C and a tensile speed of 50 mm / min in accordance with JIS K6854-3:1999 (Adhesives - Test methods for peel adhesion strength, Part 3: T-type peel).

[0051] • Evaluation criteria The adhesion was evaluated based on the peel adhesion strength measured as described above, according to the following criteria. In this invention, a peel adhesive strength of 8 N / m or higher was evaluated as indicating excellent adhesion. On the other hand, if the peel adhesion strength was less than 8 N / m, the adhesion was evaluated as poor. The results of the adhesion evaluation are shown below. ·◎:25N / m or more ○: 20 N / m or more and less than 25 N / m • △: 8N / m or more and less than 20N / m • ×: Less than 8N / m In practical terms, it is preferable to be ◎, ○, or △, more preferably ◎ or ○, and even more preferably ◎.

[0052] [Table 1]

[0053] [Table 2]

[0054] The details of each component shown in Table 1 are as follows: (rubber) • NR: Natural rubber. Product name RSS#3, Mw200,000 or more • IR: Polyisoprene. Product name: Nipol IR2200, manufactured by Zeon Corporation. Mw 300,000 or more. • SBR: Styrene-butadiene rubber. Product name E581, manufactured by Asahi Kasei Chemicals. Mw 1,000,000 or higher. • BR: Polybutadiene. Product name UBEPOL BR, manufactured by UBE Elastomers. Mw 500,000 or more. • Low molecular weight SBR (comparative): Styrene-butadiene rubber. Mw 150,000

[0055] (Vulcanization accelerator) • Dithiocarbamate-based vulcanization accelerator: n-butyldithiocarbamate zinc. Product name: Noxellar BZP (structure shown below), manufactured by Ouchi Shinko Chemical Co., Ltd. [ka] • Morpholine-based vulcanization accelerator: 4,4′-dithiodimorpholine. Trade name: Valnock R (structure shown below), manufactured by Ouchi Shinko Chemical Co., Ltd. [ka] • Sulfenamide-based vulcanization accelerator (comparative): n-cyclohexylbenzothiadylsulfenamide. Product name: Sunceller CMG. Manufactured by Sanshin Chemical Industry Co., Ltd.

[0056] • Organic solvent: cyclohexane

[0057] As is clear from the results shown in Table 1, Comparative Example 1, which did not use the specified vulcanization accelerator but instead used a sulfenamide-based vulcanization accelerator, exhibited poor adhesion. Comparative Example 2, in which the vulcanization accelerator content and rubber concentration fell outside the specified range, exhibited poor adhesion. In Comparative Example 3, where the content of the vulcanization accelerator fell outside the specified range, the resulting composition did not flow, and its adhesive properties could not be evaluated. Comparative Examples 4-7, in which the content of the vulcanization accelerator fell outside the specified range, exhibited poor adhesion. Comparative Examples 8 and 10, where the rubber concentration fell outside the specified range, exhibited poor adhesion. Comparative Example 9, in which the weight-average molecular weight of the rubber was less than 200,000, exhibited poor adhesion.

[0058] On the other hand, the adhesive composition of the present invention exhibits excellent adhesive properties. Furthermore, the peel adhesion strength in Examples 3 and 4 was greater when the rubber contained SBR (Example 3) than when it contained BR (Example 4). Similar results were obtained in the comparisons of Examples 5 and 7, and Examples 6 and 8, for the peel adhesion strength of Examples 3 and 4. Furthermore, in the application process described above, the adhesive composition of the present invention was left at 25°C for 10 minutes and then dried.

Claims

1. It contains at least one rubber selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene rubber, and polybutadiene, a dithiocarbamate-based vulcanization accelerator and / or a morpholine-based vulcanization accelerator, and an organic solvent. The weight-average molecular weight of the aforementioned rubber is 200,000 or more. The concentration of the rubber is 3.0 to 10% by mass of the total amount of the composition. The content of the dithiocarbamate-based vulcanization accelerator or the morpholine-based vulcanization accelerator is 2.0 to 10 parts by mass per 100 parts by mass of the rubber. The aforementioned organic solvent comprises at least one selected from the group consisting of toluene, xylene, cyclohexane, and n-hexane, in an adhesive composition for vulcanized rubber.

2. The adhesive composition for vulcanized rubber according to claim 1, wherein the rubber comprises styrene-butadiene rubber and / or polybutadiene.

3. The adhesive composition for vulcanized rubber according to claim 1 or 2, which is substantially free of sulfur.

4. A tire in which a vulcanized tire and a component are bonded together with the vulcanized rubber adhesive composition described in any one of claims 1 to 3.

5. The tire according to claim 4, wherein the component is a rubber container that incorporates a sensor.

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