JP2005170994A - Rubbery elastic body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbery elastic body which, obtained from a natural polyisoprenoid, has excellent mechanical characteristics and high heat resistance, low temperature resistance and weather resistance. <P>SOLUTION: The rubbery elastic body is formed from a hydrogenated product of a natural polyisoprenoid. The hydrogenated product of the natural polyisoprenoid is a polymer obtained, for example, by reacting the natural polyisoprenoid with hydrogen in a solvent in the presence of a hydrogenation catalyst. The hydrogen addition rate thereof is preferably 50% or more. The hydrogenated product of the natural polyisoprenoid preferably has a weight average mol. wt. of ≥200,000 and a mol. wt. distribution of ≥2.0. Included in the hydrogenated product of the natural polyisoprenoid are hydrogenated products of polymeric substances having isoprene units derived from, for example, Hevea brasiliensis, Ficus elastica, Eucommia ulmoides Oliver or Lactarius group mushroom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber-like elastic body and a method for producing the same, and more specifically, a rubber-like elastic body formed from a natural polyisoprenoid hydrogenated product that is structurally modified by increasing the degree of saturation of the natural polyisoprenoid by hydrogenation, and the production Regarding the law. This rubber-like elastic body is excellent in heat resistance, weather resistance, wear resistance, SET property and cold resistance, and tires, tubes, medical rubber products, latex immersion products, rubber yarns, belts, seismic isolation, vibration isolation It is useful as an industrial rubber product such as packing.

Natural polyisoprenoids are composed of isoprene units (C ₅ H ₈ ) produced by biosynthesis by certain plants and mushrooms, typified by natural rubber extracted from trees of Hevea brasiliensis species (Hevea rubber tree). Is a general term for polymers. Natural polyisoprenoids are known to be produced from many plants and mushrooms such as Lactarius genus mushrooms such as Indian rubber tree, eucommia and chichitake, in addition to Hevea rubber tree. However, natural polyisoprenoids other than natural rubber are hardly used industrially. This is because, for use as rubber, the three-dimensional structure of many polyisoprenoids is not as regular as natural rubber, the degree of polymerization is small and the molecular weight is not sufficiently large, and it is economically difficult to produce a large amount. Depending on the reason.

  Natural rubber, on the other hand, has come to be supplied stably and inexpensively through years of research and efforts such as cultivation methods and quality stabilization, and is used in various rubber products including tires. It is the most versatile rubber material. This natural rubber is excellent in rubber elasticity and strength, but is inferior in oil resistance, chemical resistance, heat resistance and weather resistance. For this reason, although it is an excellent eco-material, its application is limited and it is not used as a so-called high-performance, multifunctional material.

  In recent years, in the industry, especially in automobiles, the temperature in the engine room tends to rise in accordance with the reduction in fuel consumption and compliance with exhaust gas regulations. Rubber products used in the engine room are It has come to be used in higher temperature environments. For this reason, higher heat resistance is required for such rubber products. In addition, the trend of environmental purification is increasing in the world, and the reduction of carbon dioxide, which is one of the causes of global warming, has become a major issue. Most of the rubber and plastics industry uses synthetic rubber made of petroleum raw materials, and there is a great interest in the carbon dioxide generated during this disposal. In recent years, thermoplastic elastomers that can be reused without being discarded ( Many TPEs have been developed and used. However, it cannot be reused permanently and will eventually be discarded. In addition, since TPE uses petroleum as a raw material, it is not necessarily an ideal rubber material from the viewpoint of the world environment. For this reason, plastics made from raw materials extracted from plants and having biodegradability are being developed.

  Journal of Applied Polymer Science, Vol. 66, pp. 1647 to 1652 (1997) describes natural rubber in an organic solvent at a temperature of 100 ° C. in the presence of a rhodium complex catalyst. A method is described for reacting with hydrogen to obtain hydrogenated natural rubber. However, research in this document is limited to kinetic studies of hydrogenation reactions and thermal properties of polymers.

Journal of Applied Polymer Science, Vol. 66, pp. 1647-1652 (1997)

  An object of the present invention is to provide a rubber-like elastic body which can be produced using natural polyisoprenoid as a raw material and has excellent mechanical properties and high heat resistance, cold resistance and weather resistance.

  As a result of intensive studies to achieve the above object, the present inventors have obtained excellent mechanical properties, heat resistance and cold resistance when molding a polymer obtained by hydrogenating natural polyisoprenoid. And it discovered that the rubber-like elastic body with high weather resistance was obtained, and completed this invention.

  That is, the present invention provides a rubber-like elastic body formed from a natural polyisoprenoid hydrogenated product.

  As the natural polyisoprenoid hydrogenated product, for example, a polymer obtained by reacting natural polyisoprenoid with hydrogen in a solvent in the presence of a hydrogenation catalyst can be used. The hydrogenation rate of the natural polyisoprenoid hydrogenation product is preferably 50% or more. The natural polyisoprenoid hydrogenated product preferably has a weight average molecular weight of 200,000 or more and a molecular weight distribution of 2.0 or more. Natural polyisoprenoid hydrogenated products include, for example, hydrogenated isoprene unit polymers derived from Hevea seed rubber, Indian rubber tree, Eucommia or Lactarius mushrooms.

  Provided is a method for producing a rubber-like elastic body, which comprises subjecting a rubber composition containing a natural polyisoprenoid hydrogenated product to a molding process.

  The rubber-like elastic body of the present invention can be produced from natural polyisoprenoid and has excellent mechanical properties and high heat resistance, cold resistance and weather resistance.

The rubber-like elastic body of the present invention is formed from a natural polyisoprenoid hydrogenated product. A natural polyisoprenoid hydrogenated product can be obtained by hydrogenating (hydrogenating, hydrogenating) a natural polyisoprenoid. The natural polyisoprenoid is not particularly limited as long as it is a polymer having an isoprene unit (C ₅ H ₈ ) as a structural unit, but representative examples include polyisoprenoids derived from plants such as Hevea rubber tree, Indian rubber tree, and Eucommia. And polyisoprenoids derived from mushrooms such as Lactarius genus mushrooms such as Chichitake. As the natural polyisoprenoid, those extracted or collected from plants or mushrooms may be used as they are, or those purified by appropriate means may be used.

  The hydrogenation reaction of natural polyisoprenoid is carried out, for example, by reacting natural polyisoprenoid with hydrogen in a suitable solvent in the presence of a hydrogenation catalyst. Any solvent may be used as long as it can dissolve or disperse natural polyisoprenoids and does not inhibit the reaction. Examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; pentane, hexane, heptane, octane, decane. Aliphatic hydrocarbons such as cyclopentane, cyclohexane and methylcyclohexane; Ketones such as acetone and methyl ethyl ketone; Esters such as ethyl acetate and butyl acetate; Alcohols such as methanol, ethanol, isopropyl alcohol and butanol; Examples thereof include ethers such as diethyl ether and tetrahydrofuran; water; mixed solvents thereof. The amount of the solvent used is not particularly limited as long as the stirring operation and the like can be performed smoothly, but generally 10 to 200 parts by weight, preferably 15 to 60 parts by weight with respect to 1 part by weight of natural polyisoprenoid used as a raw material. Degree. The natural polyisoprenoid may be completely dissolved in the solvent or may be in a dispersed state.

As the hydrogenation catalyst used in the reaction, a homogeneous or heterogeneous catalyst generally used for hydrogenation of carbon-carbon double bonds can be used. Examples of homogeneous catalysts include metal complex catalysts such as rhodium complex catalysts such as RhCl (PPh ₃ ) ₃ (particularly, complex catalysts containing Group 8, Group 9 or Group 10 metal elements), carboxylic acids, and the like. Examples thereof include a nickel-trialkylaluminum catalyst. In addition, as the heterogeneous catalyst, for example, a solid catalyst such as a palladium catalyst such as Pd / CaCO ₃ (particularly, a catalytic active component containing a metal element of Group 8, 9 or 10 of the periodic table is supported on a carrier. Catalyst). The amount of the catalyst used varies depending on the type of catalyst and the like, but is generally about 0.01 to 30% by weight, preferably about 0.1 to 20% by weight, based on the natural polyisoprenoid used as a raw material.

  Although the reaction temperature varies depending on the type of catalyst, for example, when the metal complex catalyst is used, it is selected from the range of, for example, 50 to 80 ° C., preferably 60 to 80 ° C., more preferably about 65 to 75 ° C. it can. If the reaction temperature is too high, many side reactions such as rubber gelation and molecular cutting (lower molecular weight) will proceed, and a polymer suitable for rubber-like elastic bodies having the desired mechanical strength and thermal characteristics will be obtained. Becomes difficult. For example, when the reaction temperature is 90 ° C. or higher, the weight average molecular weight decreases to 180,000 after 24 hours of reaction, and a molded article having high mechanical strength and creep characteristics cannot be obtained. On the other hand, if the reaction temperature is 100 ° C. or higher, gelation occurs remarkably, and subsequent processing as a rubber cannot be performed. If the reaction temperature is too low, the reaction rate decreases, which is disadvantageous in terms of productivity.

  The reaction pressure can be appropriately selected in consideration of the reaction efficiency, operability, cost of the apparatus, etc., and varies depending on the type of catalyst, reaction temperature, etc. For example, when the metal complex catalyst or the like is used, it is usually 0. 1-15 MPa, preferably 2-10 MPa. The reaction time can be appropriately selected according to the reaction temperature and reaction pressure.

  If water is present in the reaction system, the catalytic activity may decrease, so the water in the system may be removed beforehand using a dehydrating agent such as molecular sieves before the reaction (before adding the catalyst). . The reaction is carried out in the presence of hydrogen or under the flow of hydrogen, and any reaction system such as a batch system, a semi-batch system, or a continuous system can be adopted.

  After completion of the reaction, the polymer (natural polyisoprenoid hydrogenated product) produced by the reaction can be purified and isolated by purification means such as precipitation, reprecipitation, filtration, washing and drying.

The hydrogenation rate of the natural polyisoprenoid hydrogenated product is preferably 50% or more, more preferably 70% or more, and particularly preferably 90% or more (particularly 95% or more). As the hydrogenation rate is higher, a rubbery elastic body excellent in heat resistance, aging resistance, weather resistance, wear resistance, and SET property can be obtained. Incidentally, the carbon of the hydrogenation ratio r natural polyisoprenoid in isoprenoid which is the raw material - percentage of hydrogenated carbon double bond _{[r = (D 0 -D)} / D 0 × 100 (%); D 0 is native polypeptide The amount of carbon-carbon double bonds in the isoprenoid (mol / g), D is the amount of carbon-carbon double bonds (mol / g) in the hydrogenated product after the reaction]. In the present specification, for the sake of convenience, a value assuming a homopolymer of isoprene is adopted as the amount D ₀ of carbon-carbon double bonds in the natural polyisoprenoid. The amount D of carbon-carbon double bonds in the hydrogenated product after the reaction can be determined by ¹ H-NMR or iodine value measurement.

  The weight average molecular weight of the natural polyisoprenoid hydrogenated product is, for example, 200,000 or more (about 200,000 to 3,000,000), preferably 400,000 or more (about 400,000 to 3,000,000), more preferably 600,000 or more (600,000 to 300,000). Ten thousand). If the weight average molecular weight is too small, the physical strength and creep properties are lowered, which is not preferable. As described above, when the reaction temperature of the hydrogenation reaction is too high, the weight average molecular weight decreases.

  The molecular weight distribution [Mw (weight average molecular weight) / Mn (number average molecular weight)] of the natural polyisoprenoid hydrogenated product is, for example, 2.0 or more (about 2.0 to 7.0), preferably 2.3 or more (2 .About.3 to 7.0), more preferably 2.6 or more (about 2.6 to 7.0). If the molecular weight distribution is too small, processability is lowered, which is not preferable. If the reaction temperature of the hydrogenation reaction is too high, the polymer on the high molecular weight side is easily cleaved, and the molecular weight distribution becomes small.

  The rubber-like elastic body of the present invention can be produced by subjecting a rubber composition containing the natural polyisoprenoid hydrogenated product thus obtained to a molding process (particularly, a molding process with crosslinking). Various compounding agents are added to and blended with the rubber composition according to the use of the molded product. Examples of such compounding agents include peptizers, softeners / plasticizers, crosslinking compounds, anti-aging agents, foaming agents, coupling agents, processing aids, colorants, fillers, reinforcing agents, and the like. Can be mentioned.

  Examples of the peptizer include aromatic disulfide compounds and aromatic mercaptan metal salt compounds. The softener / plasticizer includes mineral oil softener, vegetable oil softener, synthetic softener and the like.

  As the crosslinking compounding agent, a crosslinking agent, a vulcanization accelerator, a vulcanization acceleration aid, a scooter retarder, and the like are used. Examples of the crosslinking agent include sulfur, insoluble sulfur (vulcanizing agent), peroxides such as dicumyl peroxide, and oxime. The usage-amount of a crosslinking agent is about 0.3-5 weight part with respect to 100 weight part of natural polyisoprenoid hydrogenation products, for example. Examples of the vulcanization accelerator include guanidine compounds, thiuram compounds, dithiocarbamate compounds, thiazole compounds, sulfenamide compounds, and the like. The usage-amount of a vulcanization accelerator is about 0.2-5 weight part with respect to 100 weight part of natural polyisoprenoid hydrogenation products, for example. Examples of the vulcanization acceleration aid include zinc oxide. The usage-amount of a vulcanization | cure acceleration | stimulation adjuvant is about 1-10 weight part with respect to 100 weight part of natural polyisoprenoid hydrogenation products, for example. Examples of the scooter retarder include phthalic anhydride and N-cyclohexylthiophthalimide.

  Examples of the anti-aging agent include amine-based anti-aging agents, phenol-based anti-aging agents, sulfur-based secondary anti-aging agents, phosphorus-based secondary anti-aging agents, tributylthiourea, and waxes. The foaming agent includes an inorganic foaming agent and an organic foaming agent. As the coupling agent, a white filler coupling agent, a carbon black coupling agent, or the like is used. As processing aids, paraffins, hydrocarbon resins, higher fatty acids such as stearic acid, higher fatty acid amides such as stearic acid amide, higher fatty acid esters such as butyl stearate, higher fatty alcohols such as stearyl alcohol, glycerin fatty acid esters, etc. Lubricants such as partial esters of fatty acids and polyhydric alcohols, higher fatty acid metal salts such as zinc stearate; tackifiers such as coumarone resins, phenolic / terpene resins, petroleum hydrocarbon resins, rosin derivatives, etc. . The amount of the processing aid used is, for example, about 0.1 to 10 parts by weight with respect to 100 parts by weight of the natural polyisoprenoid hydrogenated product.

  As the colorant, inorganic pigments and organic pigments are used. Further, as fillers, reinforcing fillers such as carbon black and silica; reinforcing short fibers; non-reinforcing fillers such as clay, talc, carbonates, alumina hydrate, and barium sulfate; conductive materials, etc. And functional fillers. The usage-amount of a filler is 1-200 weight part with respect to 100 weight part of natural polyisoprenoid hydrogenated products, Preferably it is about 5-100 weight part.

  The molding process of the rubber composition is performed by a kneading process for kneading the rubber composition and a molding process for molding the kneaded product (compound rubber) obtained in the kneading process. Prior to the kneading step, a mastication step of masticating the natural polyisoprenoid hydrogenated product may be provided. Kneading can be performed using a two-roll or a closed biaxial kneader. Molding is a method in which a kneaded uncrosslinked fluid compounded rubber is heated and crosslinked simultaneously with molding (mold vulcanization), and a kneaded uncrosslinked fluid compounded rubber is extruded, calendered, etc. After molding, it is carried out by a method such as heat crosslinking by can vulcanization or continuous vulcanization. As a molding method in mold vulcanization, any method such as compression molding, transfer molding, injection molding, injection compression molding, and liquid injection can be adopted. After molding, finishing and surface treatment are usually performed.

  The rubber-like elastic body (molded article) of the present invention thus obtained has excellent mechanical properties and has particularly high heat resistance as compared with natural rubber. Moreover, it is excellent also in SET property and a weather resistance, and especially what was peroxide-crosslinked is also excellent in abrasion resistance. In addition, since the natural polyisoprenoid hydrogenated product is a linear pseudo-ethylene-propylene complete alternating copolymer, it has a glass transition temperature as compared with EPDM (ethylene-propylene-diene rubber) which is a typical synthetic rubber. Is low and shows excellent cold resistance. Moreover, it is excellent in workability and fatigue durability.

  The rubber-like elastic body of the present invention can be used as industrial rubber products such as tires, tubes, medical rubber products, latex immersion products, rubber yarns, belts, seismic isolation, vibration proofing, and packing.

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. The average molecular weight and molecular weight distribution of the polymer were measured using a gel permeation chromatography apparatus (GPC) under the following conditions.
Detector: Differential refractometer (RI)
Injection solution: 0.1% by weight tetrahydrofuran solution of the sample Eluent: Tetrahydrofuran Determination: Standard polystyrene conversion

Example 1
140 g of solid natural rubber [trade name “SMR-CV60”, natural rubber from Malaysia, weight average molecular weight (Mw) 1.3 million, molecular weight distribution (Mw / Mn) 5.7] was dissolved in 6.86 kg of toluene. In order to remove moisture from this solution, molecular sieves were added and allowed to stand for 1 day, and then the molecular sieves were removed by filtration. The filtrate and 8 g of the catalyst [RhCl (PPh ₃ ) ₃ ] were put into an autoclave, the inside of the autoclave was replaced with hydrogen gas, hydrogen gas was press-fitted (8 MPa), and the mixture was heated to 70 to 75 ° C. for 96 hours. The hydrogenation reaction was performed with stirring. To the solution after the reaction, methanol was added little by little until the solid rubber was completely precipitated while stirring. The solid was filtered and washed with methanol. After this filtration and washing operation was repeated three times, the solid was vacuum dried at 60 ° C. for 24 hours. The resulting solid (hydrogenated product) had a hydrogenation rate of 70%, a weight average molecular weight (Mw) of 1,000,000, and a molecular weight distribution (Mw / Mn) of 3.2.
100 parts by weight of the resulting hydrogenated product, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, and 20 parts by weight of carbon black [trade name “N220”, manufactured by Toyo Carbon Co., Ltd.] were put into a closed kneader and 40 rpm And kneading at 50 ° C. for 3 minutes. The obtained kneaded product, a vulcanization accelerator [trade name “Noxeller CZ”, N-cyclohexylbenzothiazylsulfonamide (CBS), manufactured by Ouchi Shinsei Chemical Co., Ltd.], 2.5 parts by weight, and 1 weight of sulfur The parts were kneaded with an open roll (50 ° C.) and preformed according to the shape of the mold, and then press vulcanized at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Example 2
In Example 1, except that the amount of the catalyst was 9 g, the same operation as in Example 1 was performed to obtain a hydrogenated product. The resulting hydrogenated product had a hydrogenation rate of 90%, a weight average molecular weight (Mw) of 1.14 million and a molecular weight distribution (Mw / Mn) of 3.2.
100 parts by weight of the resulting hydrogenated product, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, and 20 parts by weight of carbon black [trade name “N220”, manufactured by Toyo Carbon Co., Ltd.] were put into a closed kneader and 40 rpm And kneading at 50 ° C. for 3 minutes. The obtained kneaded product, a vulcanization accelerator [trade name “Noxeller CZ”, N-cyclohexylbenzothiazylsulfonamide (CBS), manufactured by Ouchi Shinsei Chemical Co., Ltd.], 2.5 parts by weight, and 1 weight of sulfur The parts were kneaded with an open roll (50 ° C.) and preformed according to the shape of the mold, and then press vulcanized at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Example 3
In Example 1, except that the amount of the catalyst was 18 g, the same operation as in Example 1 was performed to obtain a hydrogenated product. The resulting hydrogenated product had a hydrogenation rate of 100%, a weight average molecular weight (Mw) of 830,000, and a molecular weight distribution (Mw / Mn) of 2.7.
100 parts by weight of the obtained hydrogenated product, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, and 20 parts by weight of carbon black were put into a closed kneader and kneaded at 40 rpm and 150 ° C. for 3 minutes. The obtained kneaded product and peroxide [trade name “Peroximon F40”, manufactured by Nippon Oil & Fats Co., Ltd.] 3 parts by weight were kneaded with an open roll (50 ° C.) and pre-molded according to the mold shape, Press vulcanization (crosslinking) was performed at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Comparative Example 1
Solid natural rubber [trade name “SMR-CV60”, natural rubber from Malaysia, weight average molecular weight (Mw) 1.3 million, molecular weight distribution (Mw / Mn) 5.7] 100 parts by weight, stearic acid 1 part by weight, zinc oxide 5 20 parts by weight of carbon black [trade name “N220”, manufactured by Toyo Carbon Co., Ltd.] was put into a closed kneader and kneaded at 40 rpm and 50 ° C. for 3 minutes. The obtained kneaded product, a vulcanization accelerator [trade name “Noxeller CZ”, N-cyclohexylbenzothiazylsulfonamide (CBS), manufactured by Ouchi Shinsei Chemical Co., Ltd.], 2.5 parts by weight, and 1 weight of sulfur The parts were kneaded with an open roll (50 ° C.) and preformed according to the shape of the mold, and then press vulcanized at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Comparative Example 2
Solid natural rubber [trade name “SMR-CV60”, natural rubber from Malaysia, weight average molecular weight (Mw) 1.3 million, molecular weight distribution (Mw / Mn) 5.7] 100 parts by weight, stearic acid 1 part by weight, zinc oxide 5 Part by weight and 20 parts by weight of carbon black [trade name “N220”, manufactured by Toyo Carbon Co., Ltd.] were put into a closed kneader and kneaded at 40 rpm and 50 ° C. for 3 minutes. The obtained kneaded product and peroxide [trade name “Peroximon F40”, manufactured by Nippon Oil & Fats Co., Ltd.] 3 parts by weight were kneaded with an open roll (50 ° C.) and pre-molded according to the mold shape, Press vulcanization (crosslinking) was performed at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Comparative Example 3
EPDM (ethylene-propylene-diene rubber) [trade name “8340A”, manufactured by DSM Corporation, weight average molecular weight (Mw) 280,000, molecular weight distribution (Mw / Mn) 2.5] 100 parts by weight, stearic acid 1 part by weight Then, 5 parts by weight of zinc oxide and 20 parts by weight of carbon black [trade name “N220”, manufactured by Toyo Carbon Co., Ltd.] were charged into a closed kneader and kneaded at 40 rpm and 150 ° C. for 3 minutes. Open roll of obtained kneaded material, vulcanization accelerator [trade name “Noxeller CZ”, N-cyclohexylbenzothiazylsulfonamide (CBS), manufactured by Ouchi Shinsei Chemical Co., Ltd.], and 1 part by weight of sulfur Were kneaded (50 ° C.) and preformed according to the shape of the mold, and then press vulcanized at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Comparative Example 4
EPDM (ethylene-propylene-diene rubber) [trade name “8340A”, manufactured by DSM Corporation, weight average molecular weight (Mw) 280,000, molecular weight distribution (Mw / Mn) 2.5] 100 parts by weight, stearic acid 1 part by weight Then, 5 parts by weight of zinc oxide and 20 parts by weight of carbon black were put into a closed kneader and kneaded at 40 rpm and 150 ° C. for 3 minutes. The obtained kneaded product and peroxide [trade name “Peroximon F40”, manufactured by Nippon Oil & Fats Co., Ltd.] 3 parts by weight were kneaded with an open roll (50 ° C.) and pre-molded according to the mold shape, Press vulcanization (crosslinking) was performed at 160 ° C. for about 60 minutes to produce a 2 mm thick sheet.

Physical property evaluation test About sheets obtained in Examples and Comparative Examples, tensile test (breaking strength, breaking elongation), hardness test (hardness), thermal aging test, wear test, compression set (SET) test, glass transition temperature Measurement of (Tg) and an ozone deterioration test were performed. The results are shown in Table 1.

(Tensile test)
In accordance with JIS K6251, a 2 mm thick sheet was punched out with a No. 3 dumbbell, a tensile test was performed under conditions of 20 mm between marked lines and a tensile speed of 500 mm / min, breaking strength [TB (MPa)], breaking elongation [EB (% )] Was measured.

(Hardness test)
In accordance with JIS K6253, a hardness test was performed using a type A durometer to measure the hardness.

(Heat aging test)
In accordance with JIS K6257, a 2 mm thick sheet was punched out with a No. 3 dumbbell, heat-aged in a gear oven for 96 hours at 100 ° C., and then subjected to a tensile test and a hardness test in the same manner as described above. The degree of aging of EB and hardness [ΔTB (%), ΔEB (%), Δ hardness (%)] was measured.

(Abrasion test)
In accordance with JIS K6264, a wear test was performed using a pico abrasion tester under the conditions of 44 N load, 60 rpm, forward and reverse 20 times × 2 times, a total of 80 times, and the amount of wear (g) was measured.

(Compression set test)
In accordance with JIS K6262, a compression set (SET) test was performed using a large test piece under the conditions of 70 ° C. × 24 hours, and compression set (%) was measured.

(Measurement of glass transition temperature)
Using a dynamic viscoelasticity measuring device (DMS), the tan δ peak temperature in a temperature rising process of 20 Hz, 5 ° C./min, −100 ° C. to 100 ° C. was measured, and the glass transition temperature [Tg (° C.)] was obtained.

(Ozone degradation test)
In accordance with JIS K6259, a 2mm thick sheet is punched out with a No. 1 dumbbell (10mm width strip), stretched 50%, fixed to a dedicated holder, placed in an atmosphere of 40 ° C and ozone concentration of 50 pphm for 96 hours, ozone crack I investigated.

From a comparison between Examples 1 and 2 and Comparative Example 1, it can be seen that the rubber-like elastic body of the present invention is significantly superior in heat resistance (heat aging resistance) than an elastic body produced from natural rubber. From the comparison between Examples 1 and 2 and Comparative Example 3 and the comparison between Example 3 and Comparative Example 4, the rubbery elastic body of the present invention is a point of abrasion resistance as compared with EPDM which is a representative synthetic rubber. It can be seen that, in particular, those obtained by peroxide crosslinking (Example 3) have significantly improved wear resistance as compared with an elastic body produced from natural rubber (Comparative Example 2). Further, among the rubber-like elastic bodies of the present invention, those having a hydrogenation rate of 90% or more (Examples 2 and 3) have improved weather resistance compared to the elastic bodies produced from natural rubber (Comparative Examples 1 and 2). In particular, when the hydrogenation rate is 100% (Example 3), the weather resistance is remarkably excellent. As can be seen from the comparison between Examples 1 and 2 and Comparative Example 3, the present invention also improves the SET property. Furthermore, the rubber-like elastic body of the present invention has a glass transition temperature comparable to that of an elastic body produced from natural rubber, and is superior to EPDM in terms of cold resistance. As described above, according to the rubber-like elastic body of the present invention, it is possible to improve the disadvantages of natural rubber such as heat resistance and weather resistance while maintaining the excellent characteristics of natural rubber. Since the raw material is used, it is preferable in terms of resources and environment.

Claims (6)

  A rubber-like elastic body formed from a natural polyisoprenoid hydrogenated product.   The rubber-like elastic body according to claim 1, wherein the natural polyisoprenoid hydrogenated product is a polymer obtained by reacting natural polyisoprenoid with hydrogen in a solvent in the presence of a hydrogenation catalyst.   The rubber-like elastic body according to claim 1 or 2, wherein the hydrogenation rate of the natural polyisoprenoid hydrogenation product is 50% or more.   The rubber-like elastic body according to any one of claims 1 to 3, wherein the natural polyisoprenoid hydrogenated product has a weight average molecular weight of 200,000 or more and a molecular weight distribution of 2.0 or more.   The rubber according to any one of claims 1 to 4, wherein the natural polyisoprenoid hydrogenated product is a hydrogenated product of an isoprene unit polymer derived from Hevea seed rubber tree, Indian rubber tree, Eucommia or Lactarius genus mushroom. Elastic body. A method for producing a rubber-like elastic body, comprising subjecting a rubber composition containing a natural polyisoprenoid hydrogenated product to a molding process.