Acrylic rubber composition and acrylic rubber molded product

Abstract

To provide an acrylic rubber composition that gives a rubber crosslinked body whose compression set is reduced.SOLUTION: An acrylic rubber composition according to one aspect of the invention includes a component A: acrylic rubber and a component B: a biomass-derived filler. A content of the component B is 5-100 pts.wt. when a content of the component A is 100 pts.wt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an acrylic rubber composition and an acrylic rubber molded article. [Background technology]

[0002] Acrylic rubber is a rubber whose main component is a unit derived from an acrylic ester. Acrylic rubber has excellent heat resistance and oil resistance, and is used in automobile parts, etc. Patent Document 1 is an example of a document disclosing an invention related to acrylic rubber. This document discloses an acrylic rubber composition containing acrylic rubber, silica obtained by calcining wet-process silica, and a crosslinking agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2004-168885 Summary of the Invention [Problem to be solved by the invention]

[0004] There is still room for further reduction in compression set in the rubber molded articles obtained from the acrylic rubber compositions disclosed in the above-mentioned prior art documents.

[0005] An object of one aspect of the present invention is to provide an acrylic rubber composition that gives a cross-linked rubber product with reduced compression set. [Means for solving the problem]

[0006] In order to solve the above problems, an acrylic rubber composition according to one embodiment of the present invention includes the following Component A and Component B: Component A: acrylic rubber; Component B: biomass-derived filler; The content of the component B is 5 to 100 parts by weight, assuming that the content of the component A is 100 parts by weight. [Effects of the Invention]

[0007] According to one aspect of the present invention, there is provided an acrylic rubber composition that gives a crosslinked rubber product with reduced compression set. DETAILED DESCRIPTION OF THE INVENTION

[0008] However, the present invention is not limited to the following embodiments and various modifications may be made within the scope of the claims. Embodiments that combine 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 "A or more and B or less."

[0010] As used herein, "biomass" refers to renewable biological resources (excluding fossil resources). Biomass is typically organic material, but can also be inorganic, such as eggshells or seashells. As used herein, "biomass content" refers to the weight of biomass-derived materials relative to the dry weight.

[0011] [1. Components contained in the acrylic rubber composition] An acrylic rubber composition according to one embodiment of the present invention contains component A: acrylic rubber and component B: biomass-derived filler. The acrylic rubber composition may further contain, as an optional component, one or more selected from the group consisting of component C: biomass-derived plasticizer, component D: coupling agent, and component E: pigment. The acrylic rubber composition may further contain components other than the above-mentioned components A to E. Each of these components may contain only one type, or two or more types. Each component will be described in detail below.

[0012] [1.1. Component A: Acrylic Rubber] Component A is an acrylic rubber. Acrylic rubber is a rubber in which acrylic ester is the main monomer. In one embodiment, the acrylic rubber is ACM and / or AEM.

[0013] ACM is an acrylic rubber obtained by copolymerizing an acrylic ester and a crosslinkable monomer. The acrylic ester is one or more selected from methyl acrylate, ethyl acrylate, butyl acrylate, and methoxyethyl acrylate. Examples of the crosslinkable monomer include a carboxyl group-containing monomer, an epoxy group-containing monomer, and an active chlorine-containing monomer. Among these, a carboxyl group-containing monomer is preferred from the viewpoint of heat resistance.

[0014] Examples of carboxy group-containing monomers include α,β-ethylenically unsaturated monocarboxylic acids having 3 to 12 carbon atoms, α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms, and monoesters of α,β-ethylenically unsaturated dicarboxylic acids having 3 to 11 carbon atoms with alkanols having 1 to 8 carbon atoms. Examples of α,β-ethylenically unsaturated monocarboxylic acids having 3 to 12 carbon atoms include acrylic acid, methacrylic acid, ethylacrylic acid, crotonic acid, and cinnamic acid. Examples of α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms include butenedioic acid (fumaric acid, maleic acid, etc.), itaconic acid, citraconic acid, and chloromaleic acid. Examples of monoesters of α,β-ethylenically unsaturated dicarboxylic acids having 3 to 11 carbon atoms and alkanols having 1 to 8 carbon atoms include butenedioic acid monochain alkyl esters (monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monomethyl maleate, monoethyl maleate, monobutyl maleate, etc.), butenedioic acid monoesters having an alicyclic structure (monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, monocyclohexenyl maleate, etc.), itaconic acid monoesters (monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, etc.), and mono-2-hydroxyethyl fumarate. Among these, one or more selected from the group consisting of monobutyl fumarate, monobutyl maleate, monocyclohexyl fumarate, and monocyclohexyl maleate are preferred.

[0015] AEM is an acrylic rubber obtained by copolymerizing methyl acrylate, ethylene, and a crosslinkable monomer. Examples of the crosslinkable monomer include a carboxyl group-containing monomer. Examples and preferred examples of the carboxyl group-containing monomer are as described above.

[0016] Commercially available ACM and / or AEM may be used as component A. Examples of commercially available ACM include Nipol (Zeon Corporation) and NOXTITE (Unimatec Corporation). Examples of commercially available AEM include VAMAC (Celanese).

[0017] The acrylic rubber composition may contain a rubber component other than component A. Examples of rubbers other than component A 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), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber (U), and silicone rubber (Q).

[0018] The rubber component in the acrylic rubber composition is preferably mainly composed of component A. In one embodiment, the weight proportion of component A among all rubber components contained in the acrylic rubber composition is 70% by weight or more, 80% by weight or more, or 90% by weight or more. In one embodiment, the acrylic rubber composition does not contain any rubber component other than component A.

[0019] [1.2. Component B: Biomass-derived filler] Component B is a filler derived from biomass. Component B may be a substance obtained by processing biomass, such as by pulverizing it. Component B may be a substance synthesized using biomass as a starting material. Component B may be a composite substance of a biomass-derived material and a material not derived from biomass. The biomass content of component B may be 10% or more.

[0020] Examples of component B include biomass-derived silica, cellulose fiber, ground eggshells, and ground seashells. In one embodiment, component B is biomass-derived silica. Examples of biomass-derived silica include vegetable silica (such as rice husk silica).

[0021] In one embodiment, Component B is a white filler. By using Component B as a white filler, the acrylic rubber composition is less likely to be discolored due to Component B. Therefore, color development is improved when Component E (pigment) is blended. Examples of Component B as a white filler include biomass-derived silica and cellulose fiber.

[0022] [1.3. Component C: Biomass-derived plasticizer] Component C is a biomass-derived plasticizer. Component C may be a substance extracted from biomass. Component C may be a substance synthesized using biomass as a starting material. Component C may be obtained by synthesizing a biomass-derived raw material and a non-biomass-derived raw material. The biomass content of component C may be 10% or more.

[0023] Examples of component C include fatty oils (castor oil, linseed oil, rapeseed oil, soybean oil, palm oil, etc.) and waxes (beeswax, carnauba wax, etc.).

[0024] Commercially available products may be used as component C. Examples of commercially available products include Biocizer (Riken Vitamin Co., Ltd.); Polycizer W-1810-BIO (DIC Corporation); Adeka CycloAid PNB-205 (ADEKA Corporation); Vinicizer 105 and 124N (all manufactured by Kao Corporation); Trimex N-08A (Kao Corporation); Rika Vinyl C and S60 (all manufactured by New Japan Chemical Co., Ltd.); Sanso Cizer E-2000H and E-PO (all manufactured by New Japan Chemical Co., Ltd.); and Green Cizer BZ-100, BZ-200, BZ-300, and BZ-400 (all manufactured by New Japan Chemical Co., Ltd.).

[0025] [1.4. Component D: Coupling Agent] Component D is a coupling agent. Examples of component D include a silane coupling agent and a titanium coupling agent. Component D is preferably a silane coupling agent. Component D bonds the inorganic component and the polymer to improve the physical properties of the cross-linked acrylic rubber.

[0026] Silane coupling agents are compounds containing silicon atoms that are used to modify the surface of materials. Silane coupling agents generally have a hydrolyzable group (such as an alkoxy group) linked to the silicon atom and a reactive functional group (such as a vinyl group, (meth)acryloyl group, epoxy group, or amino group).

[0027] Examples of silane coupling agents include alkoxysilanes having a vinyl group (such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane); and alkoxysilanes having a (meth)acryloyl group (such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltrimethoxysilane). The silane coupling agent may be an oligomer of these alkoxysilanes.

[0028] 1.5. Component E: Pigment Component E is a pigment. The pigment colors the acrylic rubber composition and the acrylic rubber molded product to a desired color. 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 an appropriate ratio to produce a desired hue.

[0029] [1.6. Other Ingredients] The acrylic rubber composition may contain components that can be used in the rubber industry in addition to components A to E. Examples of such components include plasticizers and softeners other than component C, antioxidants and stabilizers, processing aids, crosslinking agents, co-crosslinking agents, crosslinking accelerators, crosslinking accelerator assistants, and crosslinking retarders.

[0030] (Plasticizers / Softeners) Examples of plasticizers other than component C 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 lubricating oils, tall oil, and sub(factice).

[0031] Examples of higher fatty acids constituting 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, arachic acid, lignoceric acid, and ricinoleic acid. The higher fatty acids may be saturated or unsaturated, and preferably contain unsaturated fatty acids. The 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.

[0032] (anti-aging agent / stabilizer) Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.

[0033] Specific examples of amine-based antioxidants include aromatic amines (e.g., phenylbutylamine, N,N-di-2-naphthyl-p-phenylenediamine) and amine ketones. Specific examples of phenol-based antioxidants include monophenols (e.g., dibutylhydroxytoluene), bisphenols, and polyphenols (e.g., tetrakis[methylene(3,5-di-t-butyl-4-hydroxy)hydrocinnamate]methane). Specific examples of sulfur-based antioxidants include thioethers (e.g., bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide), dithiocarbamates (e.g., nickel dibutyldithiocarbamate), thiourea, 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilauryl thiodipropionate, and distearyl thiodipropionate.

[0034] (processing aids) Examples of processing aids include the higher fatty acids or their salts or esters listed under plasticizers and softeners. Further examples of processing aids include higher fatty acid amides (e.g., oleic acid amide).

[0035] (Crosslinking agent) Examples of cross-linking agents include polyamine compounds. Polyamine compounds include compounds having two or more amino groups and compounds that become equipped with two or more amino groups in the cross-linking reaction environment. Suitable examples of polyamine compounds include compounds in which multiple hydrogen atoms in an aliphatic or aromatic hydrocarbon are substituted with amino groups or hydrazide groups (-CONHNH). Specific examples of polyamine compounds include aliphatic polyamine compounds (hexamethylenediamine, hexamethylenediamine carbamate, tetramethylenepentamine, hexamethylenediamine-cinnamaldehyde adduct, hexamethylenediamine-dibenzoate salt, etc.); aromatic polyamine compounds (2,2-bis{4-(4-aminophenoxy)phenyl}propane, 4,4'-methylenedianiline, m-phenylenediamine, p-phenylenediamine, 4,4'-methylenebis(o-chloroaniline), etc.); and compounds having two or more hydrazide structures (isophthalic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, etc.). Among these, aliphatic polyamine compounds are preferred, and hexamethylenediamine carbamate is particularly preferred.

[0036] 2. Composition of Acrylic Rubber Composition In the acrylic rubber composition, the lower limit of the content of Component B is 5 parts by weight or more, based on 100 parts by weight of the content of Component A. In one embodiment, the lower limit of the content of Component B may be 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, or 40 parts by weight or more, based on 100 parts by weight of the content of Component A. In one embodiment, the upper limit of the content of Component B is 100 parts by weight or less, based on 100 parts by weight of the content of Component A. In one embodiment, the lower limit of the content of Component B may be 95 parts by weight or less, 90 parts by weight or less, 85 parts by weight or less, 80 parts by weight or less, 75 parts by weight or less, 70 parts by weight or less, 65 parts by weight or less, 60 parts by weight or less, 55 parts by weight or less, or 50 parts by weight or less, based on 100 parts by weight of the content of Component A.

[0037] In the acrylic rubber composition, the lower limit of the content of Component C may be 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more, based on 100 parts by weight of the content of Component A. In the acrylic rubber composition, the upper limit of the content of Component C may be 20 parts by weight or less, 19 parts by weight or less, or 18 parts by weight or less, based on 100 parts by weight of the content of Component A.

[0038] In the acrylic rubber composition, the lower limit of the content of Component D may be 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more, based on 100 parts by weight of the content of Component A. In the acrylic rubber composition, the upper limit of the content of Component D may be 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 1 part by weight or less, based on 100 parts by weight of the content of Component A.

[0039] In the acrylic rubber composition, the lower limit of the content of Component E may be 0.01 parts by weight or more, 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.5 parts by weight or more, based on 100 parts by weight of the content of Component A. In the acrylic rubber composition, the upper limit of the content of Component E may be 10 parts by weight or less, 8 parts by weight or less, or 5 parts by weight or less, based on 100 parts by weight of the content of Component A.

[0040] In one embodiment, the biomass degree of the acrylic rubber composition is 5% or more. The biomass degree of the acrylic rubber composition may be 10% or more, 15% or more, 20% or more, 25% or more, or 30% or more. The upper limit of the biomass degree of the acrylic rubber composition may be 80% or less, 70% or less, or 60% or less. It can be said that an acrylic rubber composition having a biomass degree within the above range has a higher biomass degree and a smaller environmental impact than conventional products. In this respect, the present invention can also contribute to achieving Goal 13 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Take urgent action to combat climate change."

[0041] In order to improve the biomass content of an acrylic rubber composition, a biomass-derived component may be used or the amount of the component may be increased. As described above, at least a portion of Components B and C is a biomass-derived component. Furthermore, if the monomer constituting Component A is a biomass-derived monomer, at least a portion of Component A is also a biomass-derived component. Examples of such monomers include ethyl acrylate, butyl acrylate, and ethylene. In one embodiment, Component A is a biomass-derived monomer and contains one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, and ethylene as structural units.

[0042] [3. Cross-linked acrylic rubber and acrylic rubber molded products] The cross-linked acrylic rubber according to one embodiment of the present invention is obtained by cross-linking the acrylic rubber composition according to one embodiment of the present invention. For example, the acrylic 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 an open roll, a kneader, a planetarium mixer, a Banbury mixer, an internal mixer, and an extruder. The kneading temperature may be 25 to 200°C. The kneading time may be 1 minute to 1 hour.

[0043] A cross-linked acrylic rubber product can be produced by curing the acrylic rubber composition. The curing temperature may be 120 to 200°C. The curing time may be 10 seconds to 120 minutes. The cured molded product may be further subjected to secondary curing. The secondary curing temperature may be 120 to 250°C. The secondary curing time may be 30 minutes to 4 hours.

[0044] An acrylic rubber molded article according to one embodiment of the present invention includes the cross-linked acrylic rubber according to one embodiment of the present invention. The acrylic rubber molded article can be produced by molding and cross-linking the acrylic rubber composition. Examples of molding methods include injection molding, transfer molding, compression molding, press processing, and extrusion molding.

[0045] In one embodiment, the acrylic rubber molded article is a seal or gasket material. In this specification, a seal refers to a material that is fitted between moving members to form a seal. In this specification, a gasket refers to a material that is fitted between stationary members to form a seal.

[0046] [3.1. Physical properties of cross-linked acrylic rubber] The upper limit of the compression set of the crosslinked acrylic rubber is preferably 80% or less, more preferably 70% or less, even more preferably 60% or less, particularly preferably 50% or less, and even more preferably 40% or less. In this specification, the compression set is measured by a method in accordance with JIS K6262 (see Examples for details).

[0047] The lower limit of the Shore A hardness of the crosslinked acrylic rubber is preferably 10 or more, and more preferably 20 or more. The upper limit of the Shore A hardness of the crosslinked acrylic rubber is preferably 80 or less. If the Shore A hardness is within the above range, it can be said to have softness suitable for use as a gasket. In this specification, the Shore A hardness is measured using a Type A durometer based on JIS K6253. For more specific examples of the measurement method, see the examples of this application.

[0048] [4. Summary] The present invention includes the following aspects. <1> It contains the following ingredients A and B: Component A: acrylic rubber; Component B: biomass-derived filler; The content of the component B is 5 to 100 parts by weight, assuming that the content of the component A is 100 parts by weight. Acrylic rubber composition. <2> The component A contains a unit derived from a biomass-derived monomer. <1> The acrylic rubber composition according to claim 1. <3> Further containing the following ingredient C: <1> or <2> The acrylic rubber composition according to claim 1, Component C: Biomass-derived plasticizer. <4> Further containing the following component D: <1> ~ <3> The acrylic rubber composition according to any one of the preceding claims: Component D: Coupling agent. <5> Further containing the following ingredient E: <1> ~ <4> The acrylic rubber composition according to any one of the preceding claims: Component E: Pigment. <6> The biomass content is 5% or more. <1> ~ <5> The acrylic rubber composition according to any one of the preceding claims. <7> <1> ~ <6> The acrylic rubber composition according to any one of the preceding items is crosslinked and molded. Acrylic rubber molded product. <8> a sealing or gasket material; <7> The acrylic rubber molded product according to claim 1. [Example]

[0049] Hereinafter, one embodiment of the present invention will be described in detail with reference to examples, although the present invention is not limited to these examples.

[0050] [Materials used] Ingredient A Acrylic rubber (ACM, Nipol AR12, Zeon Corporation) ●Ingredient B Biomass silica (derived from rice husks) ●Component B' (filler other than component B) Mineral silica (from silica sand, Ultrasil VN2, Evonik) ●Component D Coupling agent (3-(2-aminoethylamino)propyltrimethoxysilane, KBM-603, Shin-Etsu Chemical Co., Ltd.) ●Ingredient E Pigment 1 (carbon black (black pigment), SEAST G116, Tokai Carbon Co., Ltd.) Pigment 2 (ferric oxide (red pigment), TODA COLOR 120ED, Toda Kogyo Co., Ltd.) ●Other Plasticizer (polyester compound, Polycizer W-320, DIC Corporation) Stearic acid Antioxidant (4,4'-bis(α,α-dimethylbenzyl)diphenylamine, Nocrac CD, Ouchi Shinko Chemical Industry Co., Ltd.) Wax (hydrocarbon, PARAFFIN WAX-135, Nippon Seiro Co., Ltd.) Crosslinking agent (hexamethylenediamine carbamate, VC-1A, Chemours Inc.) Crosslinking accelerator (1,3-di-o-tolylguanidine, Noccela DT, Ouchi Shinko Chemical Industry Co., Ltd.)

[0051] [Examples 1 to 4, Comparative Examples 1 to 3] A crosslinked rubber sheet was prepared according to the following procedure. The crosslinked rubber sheet was used to prepare test pieces for the tests described below. 1. The components listed in Table 1, excluding the crosslinking agent, were kneaded in a kneader. The temperature during kneading was 130° C. The kneading time was 10 minutes. 2. A crosslinking agent was added and the mixture was kneaded with an open roll. The temperature during kneading was 30 to 40° C. The kneading time was 10 minutes. 3. An uncrosslinked rubber sheet was produced from the resulting kneaded product. 4. The uncrosslinked rubber sheet was press-crosslinked at 170°C for 20 minutes. 5. Further, secondary crosslinking was carried out for 4 minutes at 170° C. In this way, a crosslinked rubber sheet with a thickness of 2 mm and an O-ring with a wire diameter of 2.4 mm were obtained.

[0052] [Test method] [1. Compression set] The compression set of the cross-linked acrylic rubber was measured according to JIS K6262. The specific procedure is as follows. 1. The O-rings obtained in step 5 of the examples and comparative examples were used as test specimens. 2. Using a spacer with a thickness of 1.8 mm, the test piece was compressed by 25% and held in a constant temperature bath at 150°C for a specified time, which was either 72 hours or 168 hours. 3. The test piece was removed from the thermostatic chamber and quickly released from the spacer. 4. The test piece was placed on a wooden stand and left at the standard temperature (23°C) of the test room for 30 minutes. 5. The thickness of the test piece was measured and the compression set was calculated using the following formula: Compression set (%) = (thickness of test piece before test (mm) - thickness of test piece after test (mm)) ÷ (thickness of test flame before test (mm) - thickness of spacer (mm)) × 100

[0053] [2. Shore A hardness] The Shore A hardness was measured according to JIS K6253. The specific procedure is as follows. 1. Three crosslinked rubber sheets obtained in step 5 of the examples and comparative examples were stacked to prepare a measurement sample having a thickness of 6 mm. 2. Measurement was performed using a Type A durometer, and the peak value was taken as Shore A hardness. The measurement environment was a temperature of 23°C and a relative humidity of 50%.

[0054] [3. Heat Aging Test] A heat aging test was performed in accordance with JIS K6257. The test pieces were left standing in air at 150°C for 72 hours. The increase or decrease in Shore A hardness before and after the heat aging test (hardness before the test - hardness after the test) was calculated. The Shore A hardness was measured as described above.

[0055] [4. Oil immersion test] An oil immersion test was performed in accordance with JIS K6268. Specifically, the test specimen was left standing in lubricating oil (IRM903) at 150°C for 72 hours. The change in Shore A hardness before and after the oil immersion test (hardness after test - hardness before test) was calculated. The method for measuring Shore A hardness was as described above. In addition, the rate of change in volume before and after the oil immersion test ((volume after test - volume before test) ÷ volume before test × 100) was measured. The volume measurement method was in accordance with JIS K6268.

[0056] 〔result〕 The results are shown in Table 1. [Table 1]

[0057] As can be seen from Table 1, the difference between Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 was whether or not the type of filler used was derived from biomass. In these Examples and Comparative Examples, when the cross-linked acrylic rubber of the Examples was compared with the cross-linked acrylic rubber of the Comparative Examples, the former tended to have a smaller compression set. These results suggest that the acrylic rubber composition according to one embodiment of the present invention can produce a cross-linked acrylic rubber that has a small compression set and high recovery force even after long-term compression. In particular, an acrylic rubber composition in which the amount of Component B was approximately 50 parts by weight per 100 parts by weight of Component A exhibited a remarkable effect in reducing compression set in the resulting cross-linked acrylic rubber.

[0058] Furthermore, looking at the results of the Examples and Comparative Examples, there were no significant differences in Shore A hardness, density, heat aging test results, and oil immersion test results, depending on whether the filler was biomass-derived or not. In other words, this suggests that with regard to these physical properties, the acrylic rubber composition according to one embodiment of the present invention can produce a cross-linked acrylic rubber product with performance equal to or better than that of conventional techniques.

[0059] As can be seen from Example 4, even when the type of component E was changed, a crosslinked acrylic rubber product was successfully obtained. [Industrial Applicability]

[0060] The present invention can be used for sealing materials, gasket materials, etc.

Claims

1. It contains the following components A and B, Component A: acrylic rubber; Component B: biomass-derived filler; The content of the component B is 5 to 100 parts by weight, assuming that the content of the component A is 100 parts by weight. Acrylic rubber composition.

2. The component A contains a unit derived from a biomass-derived monomer. The acrylic rubber composition according to claim 1.

3. The acrylic rubber composition according to claim 1, further comprising the following component C: Component C: Biomass-derived plasticizer.

4. The acrylic rubber composition according to claim 1, further comprising the following component D: Component D: Coupling agent.

5. The acrylic rubber composition according to claim 1, further comprising the following component E: Component E: Pigment.

6. The biomass content is 5% or more. The acrylic rubber composition according to claim 1.

7. The acrylic rubber composition according to any one of claims 1 to 6 is crosslinked and molded. Acrylic rubber molded product.

8. a sealing or gasket material; The acrylic rubber molded product according to claim 7.

Images