rubber composition

Abstract

This invention provides a rubber composition containing carbon black that has a lower environmental impact than conventional technologies. [Solution] The rubber composition of this disclosure contains component A: rubber and component B: biomass-derived carbon black.

Description

Technical Field

[0001] The present invention relates to a rubber composition.

Background Art

[0002] Carbon black is a typical additive incorporated into rubber compositions. Various rubber compositions containing carbon black have been proposed so far (see, 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] Carbon black is usually produced by incomplete combustion of fossil fuels such as petroleum at high temperatures. Therefore, conventional carbon black emits a large amount of carbon dioxide in the manufacturing process and has a high environmental impact.

[0005] One aspect of the present invention aims to provide a rubber composition containing carbon black with a reduced environmental impact compared to the prior art.

Means for Solving the Problems

[0006] The present invention includes the following aspects. <1> A rubber composition comprising the following component A and component B: " Component A: Rubber; Component B: Biomass-derived carbon black. <2> The carbon content of the above component B is 85% by weight or more based on the dry weight of component B, The rubber composition according to <1>. <3> The above component B is carbon black derived from woody biomass. <1> or <2> The rubber composition described above. <4> The content of fossil fuel-derived carbon black in the above rubber composition is 100% by weight or less, with the content of component B being 100% by weight. <1> ~ <3> A rubber composition as described in any of the following. <5> The above component A is one or more selected from the group consisting of acrylonitrile-butadiene rubber and styrene-butadiene rubber. <1> ~ <4> A rubber composition as described in any of the following. <6> <1> ~ <5> A rubber composition described in any of the above is crosslinked, Rubber crosslinked material. <7> <6> An article containing the rubber crosslinking material described above, It is a sealing material, gasket material, or magnetic encoder. Goods. [Effects of the Invention]

[0007] According to one aspect of the present invention, a rubber composition containing carbon black is provided that has a lower environmental impact than the prior art. [Modes for carrying out the invention]

[0008] The following describes in detail some examples of embodiments of the present invention, but the present invention is not limited to the embodiments described below, and various modifications may be made within the scope of the claims. Embodiments that combine the technical means described in different embodiments are also included in the technical scope of the present invention.

[0009] Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A, and less than or equal to B."

[0010] In this specification, “biomass” refers to renewable biological resources (excluding fossil resources). Biomass is usually organic material, but it can also be inorganic, such as eggshells and seashells. In this specification, “biomass content” refers to the weight of biomass-derived material relative to the dry weight.

[0011] [1. Components contained in the rubber composition] A rubber composition according to one aspect of the present invention contains component A: rubber and component B: biomass-derived carbon black. The rubber composition may further contain components other than those described above (components A and B). Each of these components may be present in single type or in two or more types. Each component will be described in detail below.

[0012] [1.1. Component A: Rubber] Component A is rubber. Rubber is a polymer that has one crosslinking point within its molecule. These crosslinking points are crosslinked by a crosslinking agent, resulting in rubber elasticity. In one embodiment, the rubber is a thermosetting polymer.

[0013] Specific examples of rubber include fluororubber (FKM), natural rubber (NR), styrene-butadiene rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR), butyl rubber (IIR), acrylic rubber (ACM), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber (U), and silicone rubber (Q). In one embodiment, component A is one or more selected from the group consisting of acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR).

[0014] Acrylonitrile-butadiene rubber is a rubber obtained by copolymerizing acrylonitrile and butadiene. The acrylonitrile-butadiene rubber may be a rubber obtained by further copolymerizing monomers other than acrylonitrile and butadiene. Examples of such rubbers include carboxylated acrylonitrile-butadiene rubber (XNBR) and acrylonitrile-butadiene-isoprene rubber (NBIR).

[0015] The acrylonitrile content in acrylonitrile-butadiene rubber is not particularly limited. The lower limit of the acrylonitrile content can be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more. The upper limit of the acrylonitrile content can be 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, or 10% or less.

[0016] Styrene-butadiene rubber is a rubber obtained by copolymerizing styrene and butadiene. Styrene-butadiene rubber can be classified by the polymerization method. Examples of such classification include emulsion polymerization styrene-butadiene rubber (E-SBR) and solution polymerization styrene-butadiene rubber (S-SBR).

[0017] The styrene content in styrene-butadiene rubber is not particularly limited. The lower limit of the styrene content can be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more. The upper limit of the styrene content can be 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, or 10% or less.

[0018] In one embodiment, the proportion of acrylonitrile butadiene rubber to the total amount of component A is 50% by weight or more, 70% by weight or more, or 90% by weight or more. In one embodiment, the proportion of styrene butadiene rubber to the total amount of component A is 50% by weight or more, 70% by weight or more, or 90% by weight or more. In one embodiment, the proportion of the total amount of acrylonitrile butadiene rubber and styrene butadiene rubber to the total amount of component A is 50% by weight or more, 70% by weight or more, or 90% by weight or more. In one embodiment, component A consists only of acrylonitrile butadiene rubber, styrene butadiene rubber, or a mixture thereof.

[0019] [1.2. Ingredient B: Biomass-derived carbon black] Component B is biomass-derived carbon black. Component B may also be a substance obtained by heat treatment or other processes on biomass. Component B may also be a substance synthesized using biomass as a starting material. Component B may also be a composite material of biomass-derived material and non-biomass-derived material. The biomass content of component B may be 10% or more.

[0020] By incorporating component B, the environmental impact of the rubber composition is reduced (in particular, carbon emissions are reduced). This effect can contribute to achieving Goal 13 of the United Nations' Sustainable Development Goals (SDGs), "Take urgent action to combat climate change and its impacts."

[0021] The biomass used as the raw material for component B is, for example, a plant-derived material. Specific examples of such materials include woody biomass (wood, bamboo, lignin extracted from woody raw materials, etc.), grass biomass (rice husks, etc.), vegetable oil, and bioethanol. In one embodiment, component B is carbon black derived from woody biomass.

[0022] The carbon content of component B is not particularly limited. The lower limit of the carbon content may be 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more, with the weight of component B being 100% by weight. The upper limit of the carbon content may be 100% by weight or less, 99% by weight or less, 98% by weight or less, or 97% by weight or less, with the weight of component B being 100% by weight.

[0023] The rubber composition may contain carbon black derived from fossil fuels in addition to component B. For the purpose of reducing environmental impact, the content of carbon black derived from fossil fuels is preferably 100% by weight or less, with the content of component B being 100% by weight. The content of carbon black derived from fossil fuels may be 90% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, or 10% by weight or less, with the content of component B being 100% by weight. In one embodiment, the rubber composition does not contain carbon black derived from fossil fuels. In one embodiment, the carbon black derived from fossil fuels is petroleum-derived carbon black.

[0024] [1.3. Other Ingredients] The rubber composition may also contain components other than components A to B that can be used in the rubber industry. Examples of such components include fillers, plasticizers / softeners, antioxidants / stabilizers, processing aids, coupling agents, pigments, crosslinking agents, co-crosslinking agents, crosslinking accelerators, crosslinking accelerators, and crosslinking retarders.

[0025] (Filler) Examples of fillers include silica, calcium carbonate, and clay. Substances that impart specific functions (such as conductivity or magnetism) may also be used as fillers.

[0026] (Plasticizers / Softeners) Examples of plasticizers include coal tar, higher fatty acids or their salts or esters, naphthenic acid, pine oil, rosin or its derivatives, synthetic polymers (terpene resins, petroleum resins, coumarone indene resins, etc.), ester-based plasticizers (dioctyl phthalate, dioctyl adipate, etc.), microcrystalline wax, poly-α-olefins (liquid polybutadiene, modified liquid polybutadiene, etc.), hydrocarbon-based synthetic lubricants, tall oil, and sub-(factis).

[0027] Examples of higher fatty acids that constitute higher fatty acids or their salts or esters include oleic acid, palmitic acid, stearic acid, lauric acid, linoleic acid, abietic acid, erucic acid, myristic acid, arachidic acid, lignoceric acid, and ricinoleic acid. Higher fatty acids may be saturated or unsaturated fatty acids, and preferably contain unsaturated fatty acids. Salts of higher fatty acids are usually metal salts, preferably alkali metal salts or alkaline earth metal salts. Examples of metal salts include lithium salts, potassium salts, sodium salts, barium salts, calcium salts, magnesium salts, aluminum salts, iron salts, and zinc salts. Specific examples of higher fatty acids or their salts include ricinoleic acid, palmitic acid, stearic acid, lauric acid, barium stearate, zinc stearate, and calcium stearate.

[0028] (Anti-aging agent / stabilizer) Examples of antioxidants include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.

[0029] Specific examples of amine-based antioxidants include aromatic amines (phenylbutylamine, N,N-di-2-naphthyl-p-phenylenediamine, etc.) and amine ketones. Specific examples of phenol-based antioxidants include monophenols (dibutylhydroxytoluene, etc.), bisphenols, and polyphenols (tetrakis[methylene(3,5-di-t-butyl-4-hydroxy)hydrocinnamate]methane, etc.). Specific examples of sulfur-based antioxidants include thioethers (bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide, etc.), dithiocarbamates (nickel dibutyldithiocarbamate, etc.), thioureas, 2-mercaptobenzoylimidazole, 2-mercaptobenzoimidazole, zinc salts of 2-mercaptobenzoimidazole, dilaurylthiodipropionate, and distearylthiodipropionate.

[0030] (Processing aid) Examples of processing aids include higher fatty acids or their salts or esters, as listed in the section on plasticizers and softeners. Further examples of processing aids include higher fatty acid amides (such as oleic acid amides).

[0031] (Coupling agent) Examples of coupling agents include silane coupling agents and titanium coupling agents. The coupling agent may be included in the rubber composition in the form of other components treated with the coupling agent (such as coupling agent-treated fillers).

[0032] (Pigment) Examples of pigments include organic pigments, inorganic pigments, and fluorescent pigments. Examples of pigment hues include black, red, blue, yellow, green, brown, and white. Two or more types of pigments may be blended in appropriate ratios to produce the desired hue.

[0033] (Crosslinking agent) A crosslinking agent is a component that crosslinks the polymer chains of component A to impart rubber elasticity. A person skilled in the art can select an appropriate crosslinking agent depending on the type of component A. Examples of crosslinking agents include sulfur, organic peroxides, quinoids, resins, amines, metal oxides, triazinethiols, and polyols.

[0034] [2. Composition of the rubber composition] In a rubber composition, the lower limit of the content of component B may be 1 part by weight or more, 5 parts by weight or more, 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more and 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or more, based on the content of component A per 100 parts by weight. In a rubber composition, the upper limit of the content of component B may be 100 parts by weight or less, 90 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, 60 parts by weight or less, 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less, based on the content of component A per 100 parts by weight.

[0035] [3. Rubber Crosslinked Materials and Articles] A crosslinked rubber body according to one aspect of the present invention is obtained by crosslinking a rubber composition according to one aspect of the present invention. For example, a rubber composition can be produced by kneading the components described in Section [1]. A kneader can be used to knead the components. Examples of kneaders include open rolls, kneaders, planetarium mixers, Banbury mixers, internal mixers, and extruders. The kneading temperature may be 25 to 200°C. The kneading time may be 1 minute to 1 hour.

[0036] A rubber crosslinked body can be produced by curing a rubber composition. The curing temperature may be 120 to 200°C. The curing time may be 10 seconds to 120 minutes. The cured molded body may be further second-cured. The second-curing temperature may be 120 to 250°C. The second-curing time may be 30 minutes to 4 hours.

[0037] An acrylic rubber molded article according to one aspect of the present invention includes a rubber crosslinked body according to one aspect of the present invention. An acrylic rubber molded article can be produced by molding and crosslinking a rubber composition. Examples of molding methods include injection molding, transfer molding, compression molding, press working, and extrusion molding.

[0038] An article according to one aspect of the present invention includes a rubber crosslinked body according to one aspect of the present invention. This article is a sealing material, a gasket material, or a magnetic encoder. In this specification, a sealing material refers to a material that is installed between moving members to create a seal. In this specification, a gasket material refers to a material that is installed between stationary members to create a seal. In this specification, a magnetic encoder refers to a device that detects changes in position or rotation angle as changes in a magnetic field, converts them into an electrical signal, and outputs it. [Examples]

[0039] One embodiment of the present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples.

[0040] A rubber composition and a rubber crosslinked material were prepared using acrylonitrile butadiene rubber (NBR) as component A.

[0041] [Materials used] ●Ingredient A • Acrylonitrile butadiene rubber (NBR, JSR N241, JSR Corporation) ●Ingredient B • Biomass-derived carbon black (derived from cedar wood, manufactured in-house) ●Component B' (filler that is not component B) • Fossil fuel-derived carbon black 1 (MAF, Seast 116, Tokai Carbon Co., Ltd.) • Fossil fuel-derived carbon black 2 (HAF, Seast 3, Tokai Carbon Co., Ltd.) ●Other ·clay • Plasticizer (polyether ester type, ADEKA RS-700, ADEKA Corporation) Zinc oxide Stearic acid • Anti-aging agent (alkylated diphenylamine, Nocrack ODA, Ouchi Shinko Chemical Industry Co., Ltd.) • Wax (paraffin wax, paraffin wax-135, Nippon Seiro Co., Ltd.) • Crosslinking agent (sulfur, Sulfax A, Tsurumi Chemical Industries Co., Ltd.) • Crosslinking accelerator 1 (dibenzothiazole disulfide, Noxellar DM-P, Ouchi Shinko Chemical Industry Co., Ltd.) • Crosslinking accelerator 2 (tetramethylthiuram disulfide, Noxellar TT-P, Ouchi Shinko Chemical Industry Co., Ltd.)

[0042] [Test Method] (1) Shore A hardness Shore A hardness was measured using a method compliant with JIS K6253. The specific procedure is as follows: 1. Three cross-linked rubber sheets obtained in the examples and comparative examples were stacked to create a measurement sample with a thickness of 6 mm. 2. Measurements were taken using a Type A durometer, and the peak value was defined as Shore A hardness. The measurement environment was temperature: 23°C and relative humidity: 50%.

[0043] (2) Tensile test Tensile tests were conducted in accordance with JIS K6251. The test specimens were dumbbell-shaped, JIS type 6. The tensile speed was 500 mm / min. The measured parameters were 100% modulus, tensile strength, and elongation at break.

[0044] (3) Thermal aging test A thermal aging test was conducted in accordance with JIS K6257. Specifically, the test specimens were left standing in air at 100°C for 70 or 336 hours. The increase or decrease in Shore A hardness (hardness before test - hardness after test), the rate of change in tensile strength ((strength before test - strength after test) ÷ strength before test × 100), and the rate of change in elongation at break ((elongation before test - elongation after test) ÷ elongation before test × 100) were calculated before and after the thermal aging test. The method for measuring Shore A hardness and the method for conducting the tensile test are as described above.

[0045] [Examples 1-2, Comparative Examples 1-2] A cross-linked rubber sheet was prepared according to the following procedure. Test specimens used in the above-mentioned test were prepared from this cross-linked rubber sheet. 1. Each component, excluding the crosslinking agent and crosslinking accelerator listed in Table 1, was kneaded in a kneader. The kneading temperature was 120°C. The kneading time was 10 minutes. 2. The crosslinking agent and crosslinking accelerator were added and the mixture was kneaded in an open roll. The kneading temperature was 60°C. The kneading time was 10 minutes. 3. An uncrosslinked rubber sheet was prepared from the resulting mixture. 4. The uncrosslinked rubber sheet was press-crosslinked at 170°C for 10 minutes.

[0046] [result] The results are shown in Table 1. [Table 1]

[0047] As can be seen from Table 1, the acrylonitrile-butadiene rubber crosslinked material containing biomass-derived carbon black exhibited physical properties comparable to those of the acrylonitrile-butadiene rubber crosslinked material containing fossil fuel-derived carbon black. In other words, an acrylonitrile-butadiene rubber crosslinked material with physical properties comparable to conventional products and reduced environmental impact was obtained. [Industrial applicability]

[0048] This invention can be used in articles containing rubber crosslinked materials, etc.

Claims

1. A rubber composition containing the following components A and B: Component A: Rubber; Component B: Biomass-derived carbon black.

2. The carbon content of component B is 85% by weight or more, based on the dry weight of component B. The rubber composition according to claim 1.

3. The above component B is carbon black derived from woody biomass. The rubber composition according to claim 1.

4. The content of fossil fuel-derived carbon black in the above rubber composition is 100% by weight or less, with the content of component B being 100% by weight. The rubber composition according to claim 1.

5. The above component A is one or more selected from the group consisting of acrylonitrile butadiene rubber and styrene butadiene rubber. The rubber composition according to claim 1.

6. A rubber composition obtained by crosslinking the rubber composition according to any one of claims 1 to 5, Rubber crosslinked material.

7. An article comprising the rubber crosslinking body described in claim 6, It is a sealing material, gasket material, or magnetic encoder. Goods.

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