Rubber composition and method for manufacturing the same

Abstract

To provide a rubber composition with excellent wear resistance.SOLUTION: A rubber composition is produced by applying crosslinking treatment to an unvulcanized rubber composition to crosslink the rubber component, where the unvulcanized rubber composition includes the rubber component with added silsesquioxane including a plurality of functional groups with C-C double bonds.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition and a method for producing the same.

Background Art

[0002] It is known to use silsesquioxane as a rubber compounding agent. For example, Patent Document 1 discloses a rubber composition for tires containing silsesquioxane.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a rubber composition having excellent wear resistance.

Means for Solving the Problems

[0005] The present invention relates to a rubber composition obtained by subjecting an uncrosslinked rubber composition, in which silsesquioxane having a plurality of functional groups containing a C-C double bond is added to a rubber component, to a crosslinking treatment for crosslinking the rubber component The silsesquioxane having multiple functional groups including the CC double bond includes an octavilonsilsesquioxane derivative in which triphenylsilane is added to one to six of the eight vinyl groups of octavilonsilsesquioxane. .

[0006] The present invention relates to a method for producing a rubber composition, comprising preparing an uncrosslinked rubber composition by adding silsesquioxane having a plurality of functional groups containing a C-C double bond to a rubber component, and subjecting the uncrosslinked rubber composition to a crosslinking treatment for crosslinking the rubber component The silsesquioxane having multiple functional groups including the CC double bond includes an octavilonsilsesquioxane derivative in which triphenylsilane is added to one to six of the eight vinyl groups of octavilonsilsesquioxane. .

Effects of the Invention

[0007] According to the present invention, by incorporating silsesquioxane having multiple functional groups containing CC double bonds into the uncrosslinked rubber composition before crosslinking, excellent abrasion resistance can be obtained in the crosslinked rubber composition. [Modes for carrying out the invention]

[0008] The embodiments will be described in detail below.

[0009] The rubber composition according to this embodiment is obtained by crosslinking an uncrosslinked rubber composition to which a silsesquioxane (hereinafter referred to as "silsesquioxane X") having a plurality of functional groups including a CC double bond represented by the following formula (A) is added to the rubber component, and then crosslinking the rubber component.

[0010] [ka]

[0011] Therefore, the rubber composition according to the embodiment can be produced by preparing an uncrosslinked rubber composition in which silsesquioxane X is added to the rubber component, and then subjecting the uncrosslinked rubber composition to a crosslinking treatment to crosslink the rubber component.

[0012] According to the rubber composition of this embodiment, by incorporating silsesquioxane X into the uncrosslinked rubber composition before crosslinking, excellent abrasion resistance can be obtained in the rubber composition after crosslinking. This is presumed to be because silsesquioxane X functions as a crosslinking aid. In other words, the crosslinking between polymer molecules of the rubber component by the crosslinking treatment includes crosslinking via silsesquioxane X, and as a result, a highly crystalline cage-like silsesquioxane skeleton having chemically stable siloxane bonds is introduced into the crosslinked structure of the rubber component.

[0013] Examples of rubber components include natural rubber (NR) and synthetic rubber. Examples of synthetic rubber include isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene-α-olefin elastomers such as ethylene-propylene copolymer rubber (EPR) and ethylene-propylene diene copolymer rubber (EPDM), acrylic rubber (ACM), urethane rubber (U), silicone rubber (Q), and fluororubber (F). It is preferable that the rubber component contains one or more of these.

[0014] The rubber component preferably contains HNBR. In that case, the amount of acrylonitrile bound to the HNBR is preferably 25% by mass or more and 45% by mass or less, more preferably 33% by mass or more and 39% by mass or less. The iodine value of the HNBR is preferably 5 mg / 100 mg or more and 60 mg / 100 mg or less, more preferably 9 mg / 100 mg or more and 12 mg / 100 mg or less.

[0015] Examples of functional groups R containing a CC double bond in silsesquioxane X include an alkenyl group such as the vinyl group shown in formula (1) below, the allyl group shown in formula (2) below, an acryloyloxyalkyl group such as the acryloyloxypropyl group shown in formula (3) below, and a methacryloyloxyalkyl group such as the methacryloyloxypropyl group shown in formula (4) below. It is preferable that the functional group R contains a CC double bond at its terminus. Multiple functional groups R may be the same or different.

[0016] [ka]

[0017] Examples of silsesquioxane X include octavinylsilsesquioxane represented by the following formula (I) and derivatives thereof. Examples of the octavinylsilsesquioxane derivatives include addition compounds in which triphenylsilane or the like is added to 1 to 6 of the 8 vinyl groups of octavinylsilsesquioxane. Silsesquioxane X preferably contains octavinylsilsesquioxane and / or a derivative thereof, and from the perspective of reducing the symmetry of the molecule to enhance dispersibility in the rubber component, it more preferably contains an octavinylsilsesquioxane derivative, and even more preferably contains an addition compound in which triphenylsilane is added to 1 of the 8 vinyl groups of octavinylsilsesquioxane represented by the following formula (II).

[0018]

Chemical Formula

[0019] From the viewpoint of obtaining excellent wear resistance, the blending amount of silsesquioxane X in the uncrosslinked rubber composition is preferably 0.5 parts by mass or more and 3 parts by mass or less, more preferably 0.8 parts by mass or more and 2.5 parts by mass or less, and still more preferably 1 part by mass or more and 2 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0020] Examples of rubber compounding agents other than silsesquioxane X include crosslinking agents, crosslinking aids (co-crosslinking agents), reinforcing materials such as carbon black and silica, fillers, processing aids, anti-aging agents, plasticizers, vulcanization accelerators, vulcanization acceleration aids, and the like.

[0021] Examples of the crosslinking treatment for crosslinking the rubber component include a thermal crosslinking treatment in which a crosslinking agent is blended into the uncrosslinked rubber composition followed by heating, and a radiation crosslinking treatment in which the uncrosslinked rubber composition is irradiated with radiation.

[0022] Examples of thermal crosslinking treatments include sulfur vulcanization using sulfur as the crosslinking agent, peroxide crosslinking using organic peroxides as the crosslinking agent, polyol crosslinking using bisphenols as the crosslinking agent, amine crosslinking using diamines as the crosslinking agent, oxime crosslinking using p-benzoquinone dioxime as the crosslinking agent, and metal crosslinking using metal oxides such as zinc oxide as the crosslinking agent. The thermal crosslinking treatment method is appropriately selected depending on the type of rubber component, but peroxide crosslinking is preferred among these because it can be applied to many rubber components and provides excellent abrasion resistance with silsesquioxane X.

[0023] Examples of organic peroxides used as crosslinking agents for peroxide crosslinking include 1,4-bis[(t-butylperoxy)isopropyl]benzene, benzoyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, n-butyl-4,4-bis(t-butylperoxy)valerate, dicumyl peroxide, and 2,5-dimethyl2,5-di(t-butylperoxy)hexane. The organic peroxide crosslinking agent preferably contains one or more of these. In particular, when the rubber component contains HNBR, the organic peroxide crosslinking agent preferably contains a dialkyl peroxide, and more preferably contains 1,4-bis[(t-butylperoxy)isopropyl]benzene. From the viewpoint of obtaining excellent abrasion resistance, the amount of organic peroxide used as a crosslinking agent in the uncrosslinked rubber composition is preferably 0.5 parts by mass or more and 3.5 parts by mass or less, and more preferably 1 part by mass or more and 3 parts by mass or less, per 100 parts by mass of the rubber component.

[0024] Examples of radiation used in radiation crosslinking include alpha rays, beta rays, gamma rays, electron beams, and ions.

[0025] The rubber composition according to the above embodiment can be used, for example, as a forming material for rubber products that require wear resistance, such as sealing materials that come into contact with and slide against other components. [Examples]

[0026] (Rubber composition) Rubber compositions for Examples 1 and 2, as well as comparative examples, were prepared. Their respective compositions are also shown in Table 1.

[0027] <Example 1> The rubber component was HNBR (bonded acrylonitrile content: 36.2% by mass, iodine value: 11 mg / 100 g). To 100 parts by mass of this rubber component, 0.89 parts by mass of octavinylsilsesquioxane, 2 parts by mass of the crosslinking agent 1,4-bis[(t-butylperoxy)isopropyl]benzene, and 40 parts by mass of the reinforcing material carbon black (FEF) were added and kneaded to prepare an uncrosslinked rubber composition. This uncrosslinked rubber composition was subjected to thermal crosslinking treatment to prepare the rubber compositions for the test pieces of each test, and these were designated as Example 1.

[0028] <Example 2> Octavinylsilsesquioxane derivatives were prepared by adding triphenylsilane to the vinyl group of octavinylsilsesquioxane. NMR analysis of these octavinylsilsesquioxane derivatives confirmed that the main component was an adduct compound in which triphenylsilane was added to one of the eight vinyl groups of octavinylsilsesquioxane.

[0029] Except for adding 1.43 parts by mass of this octavinylsilsesquioxane derivative per 100 parts by mass of the rubber component, rubber compositions for test pieces were prepared in the same manner as in Example 1, and these were designated as Example 2.

[0030] Furthermore, regarding the amount of octavinylsilsesquioxane derivative, it was assumed that the entire amount was an adduct compound in which triphenylsilane was added to one of the eight vinyl groups of octavinylsilsesquioxane, and the amount was set so that it had the same number of vinyl groups as the octavinylsilsesquioxane in Example 1.

[0031] <Comparative Example> Rubber compositions for test specimens were prepared in the same manner as in Example 1, except that octabinylsesquioxane was not added, and these were used as comparative examples.

[0032] [Table 1]

[0033] (Test method) <Hardness> For each of Examples 1 and 2 and the comparative example, the hardness was measured using a Type A durometer in accordance with JIS K6253:2012.

[0034] <Tensile properties> For each of Examples 1 and 2, as well as the comparative example, the tensile strength at break, elongation at break, and tensile stress at 100% elongation at room temperature were measured in accordance with JIS K6251:2017.

[0035] <density> The density of each of Examples 1 and 2, as well as the comparative example, was measured according to JIS K6268:1998.

[0036] <Compression set> For each of Examples 1 and 2 and the comparative example, the compression set was measured according to JIS K6262:2013, with a test temperature of 150°C and a test time of 72 hours.

[0037] <Heat aging> For each of Examples 1 and 2 and the Comparative Example, the materials were heat-aged according to JIS K6257:2017 at a temperature of 150°C for 72 hours. After that, the hardness was measured according to JIS K6253:2012, and the change from the unheat-aged material was calculated. In addition, the tensile strength and elongation at break at room temperature were measured according to JIS K6251:2017, and the percentage change from the unheat-aged material was calculated.

[0038] <Abrasion Resistance> For each of Examples 1 and 2, and the comparative example, the wear amount (dimensions) was measured after applying a load of 15N to a SUS plate and sliding it 80,000 times at a speed of 60 cpm with a stroke of 10 mm.

[0039] (Test results) The test results are shown in Table 2. According to Table 2, Examples 1 and 2 exhibit superior abrasion resistance compared to the comparative example.

[0040] Furthermore, it can be seen that Example 2 has superior abrasion resistance compared to Example 1. This is presumed to be because, in Example 1, the symmetry of the octavinylsilsesquioxane molecule is high and its dispersibility in the rubber component is poor, resulting in uneven physical properties, whereas in Example 2, the symmetry of the octavinylsilsesquioxane derivative molecule is low and its dispersibility in the rubber component is excellent, resulting in uniform physical properties.

[0041] [Table 2] [Industrial applicability]

[0042] This invention is useful in the technical field of rubber compositions and methods for producing the same.

Claims

1. A rubber composition obtained by subjecting an uncrosslinked rubber composition to which a silsesquioxane having multiple functional groups containing C-C double bonds is added to the rubber component, to a crosslinking treatment that crosslinks the rubber component, A rubber composition comprising a silsesquioxane derivative having multiple functional groups containing a C-C double bond, wherein triphenylsilane is attached to one to six of the eight vinyl groups of octavinylsilsesquioxane.

2. In the rubber composition described in claim 1, A rubber composition in which the functional group containing the C-C double bond is a vinyl group.

3. In the rubber composition described in claim 1, A rubber composition in which the amount of silsesquioxane having multiple functional groups containing the C-C double bond in the uncrosslinked rubber composition is 0.5 parts by mass or more and 3 parts by mass or less per 100 parts by mass of the rubber component.

4. In the rubber composition described in claim 1, A rubber composition comprising the aforementioned rubber component hydrogenated nitrile rubber.

5. In the rubber composition described in claim 1, A rubber composition comprising the aforementioned uncrosslinked rubber composition, an organic peroxide as a crosslinking agent, and the aforementioned uncrosslinked rubber composition subjected to a thermal crosslinking treatment to crosslink the rubber components with peroxide.

6. A method for producing a rubber composition, comprising preparing an uncrosslinked rubber composition by adding silsesquioxane having multiple functional groups containing C-C double bonds to the rubber component, and subjecting the uncrosslinked rubber composition to a crosslinking treatment to crosslink the rubber component, A method for producing a rubber composition comprising an octavilonsilsesquioxane derivative having multiple functional groups containing a C-C double bond, wherein one to six of the eight vinyl groups of octavilonsilsesquioxane are attached to triphenylsilane.

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