JP2017110094A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-damping rubber composition that is excellent in shape followability at ordinary temperature, rigidity and rubber elasticity.SOLUTION: Provided is a rubber composition characterized in containing 4-methyl-1-pentene/α-olefin copolymer (B) satisfying all of the following requirements (a) to (d) by 10-100 pts.mass per 100 pts.mass of a rubber component (A) containing a conjugated diene monomer unit. The rubber composition has: (a) a constitutional unit (i) derived from 4-methyl-1-pentene by 15-90 mol% and a constitutional unit (ii) derived from α-olefin (here, excluding 4-methyl-1-pentene) by 10-85 mol% (the sum of the proportion of the structural unit (i) and the proportion of the structural unit (ii) is 100 mol%.); (b) an intrinsic viscosity at 135°C in decalin [η] of 0.5-5.0 dL/g; (c) a GPC measurement molecular weight distribution (Mw/Mn) of 1.0-3.5; and (d) a density of 830-880 kg/m.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition, and more particularly to a rubber composition for a sealing material used for sealing various industrial products.

  Rubber seals for the purpose of giving various industrial products a buffer function to prevent fluids such as water or moisture from entering them and to protect the products from external mechanical loads. It is widely known to provide materials.

  As such a rubber-based sealing material, for example, a sealing material containing a polyisobutylene having a viscosity average molecular weight of 50,000 to 90,000 and an inorganic filler has been proposed (for example, Patent Document 1). Further, for example, a hot-melt type sealing agent composition containing butyl rubber and crystalline polyethylene has been proposed (for example, Patent Document 2).

  In order to provide the sealing material proposed in Patent Document 1 or the sealing agent composition proposed in Patent Document 2 at a specific location of a specific industrial device, the composition or the sealing material is heated and melted, It is applied by a method of applying to a specific location and then cooling the sealing material at room temperature.

JP 2006-117758 A Japanese Patent Laid-Open No. 10-110072

  Since the sealing material proposed in Patent Document 1 and the sealing agent composition proposed in Patent Document 2 have low shape followability at room temperature, depending on the complexity of the structure of the seal part, the sealing material composition is heated once to a high temperature. It had to be melted and then cooled. Moreover, in these sealing materials and sealing agent compositions, it is necessary to provide time for heating and cooling separately. In some cases, vibration suppression is not sufficient.

  Furthermore, the sealing material proposed in Patent Document 1 and the sealing agent composition proposed in Patent Document 2 may have insufficient material rigidity or rubber elasticity, and may be used as a sealing material depending on the type of industrial product. In some cases, this was insufficient.

  An object of the present invention is to provide a vibration-damping rubber composition excellent in shape following property, rigidity and rubber elasticity at room temperature, and thereby a rubber composition for a sealing material that can effectively seal a specific part of various industrial products. Is to provide.

That is, the gist of the present invention is as follows.
[1] For 100 parts by mass of the rubber component (A) containing a conjugated diene monomer unit,
Rubber containing 10 to 100 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (B) satisfying the following requirements (a), (b), (c) and (d) Composition.
(A) From the structural unit (i) derived from 15 to 90 mol% of 4-methyl-1-pentene and 10 to 85 mol% of an α-olefin (excluding 4-methyl-1-pentene). The derived structural unit (ii) (however, the sum of the proportion of the structural unit (i) and the proportion of the structural unit (ii) is 100 mol%).
(B) The intrinsic viscosity [η] measured at 135 ° C. in decalin is in the range of 0.5 to 5.0 dL / g.
(C) The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) (molecular weight distribution; Mw / Mn) is in the range of 1.0 to 3.5. It is in.
(D) The density is in the range of 830 to 880 kg / m ³ .
[2] The rubber composition according to [1], wherein the conjugated diene monomer is isoprene or butadiene.
[3] The rubber component (A) containing the conjugated diene monomer unit comprises natural rubber (NR) and / or polyisoprene rubber (IR), butadiene-acrylonitrile copolymer (NBR), and styrene-butadiene. The rubber composition according to [1] or [2], comprising at least one of a copolymer (SBR) and an isobutylene-isoprene copolymer (IIR) as a main component.
[4] The rubber composition according to any one of [1] to [3], wherein the α-olefin is propylene.

  Since the rubber composition of the present invention is a vibration-damping rubber composition excellent in shape following property, rigidity and rubber elasticity at room temperature, it is a rubber for sealing materials that can effectively seal a specific part of various industrial products. Used as a composition.

Hereinafter, the rubber composition of the present invention will be described in detail.
The rubber composition of the present invention comprises 10 to 100 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (B) having specific physical properties with respect to 100 parts by mass of the specific rubber component (A). It is characterized by containing.

≪Rubber component (A) ≫
The rubber component (A) according to the present invention contains a conjugated diene monomer unit. Examples of the rubber component (A) include a polymer obtained by polymerizing a conjugated diene hydrocarbon, a copolymer obtained by polymerizing a conjugated diene hydrocarbon and a monoolefin unsaturated compound, and the like.

  Specific examples of the conjugated diene hydrocarbon include 1,3-butadiene, isoprene, chloroprene, and the like, and preferably 1,3-butadiene or isoprene. These compounds are used alone or in combination of two or more.

  Specific examples of the monoolefin unsaturated compound include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, and methacrylamide. , Vinyl methacrylamide, acrylic acid ester, methacrylic acid ester, acrylic acid, methacrylic acid and the like.

  The polymer (rubber) obtained by polymerizing the above conjugated diene hydrocarbon or the copolymer (rubber) obtained by polymerizing a conjugated diene hydrocarbon and a monoolefin unsaturated compound is particularly limited. Specifically, butadiene polymer, isoprene polymer, chloroprene polymer, styrene-butadiene copolymer, styrene isoprene polymer, styrene-chloroprene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer. , Acrylonitrile-chloroprene copolymer, acrylic ester-isoprene copolymer, acrylic ester-chloroprene copolymer, methacrylic ester and conjugated diene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene- Isoprene-styrene block Rimmer, styrene - butadiene - styrene block polymer and the like. These polymers may be emulsion-polymerized or solution-polymerized.

  Among the rubbers described above, the rubber component (A) constituting the rubber composition of the present invention is preferably a polymer having a glass transition temperature (Tg) of 0 ° C. or less in terms of flexibility and rubber elasticity. Specifically, natural rubber (NR), acrylonitrile butadiene rubber (NBR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), polyisobutylene (butyl rubber, IIR) , Polystyrene-polybutadiene-polystyrene (SBS), polystyrene-polyisoprene-polystyrene (SIS), and the like. Among these, natural rubber (NR) and / or polyisoprene rubber (IR), butadiene-acrylonitrile copolymer (NBR), and styrene-butadiene from the point of balance between performance and cost when used as a rubber composition. Those having at least one of a copolymer (SBR) and an isobutylene-isoprene copolymer (IIR) as a main component are preferred. Examples of natural rubber include so-called raw rubber obtained by coagulating rubber sap with an acid, washing with water and drying. Moreover, what was concentrated to 60 to 70% of rubber | gum content with latex can also be used.

<< 4-methyl-1-pentene / α-olefin copolymer (B) >>
The 4-methyl-1-pentene / α-olefin copolymer (B) satisfies the following requirements (a), (b), (c) and (d). In the following description, the copolymer (B) may be abbreviated as a copolymer component (B).

Requirement (a);
The 4-methyl-1-pentene / α-olefin copolymer (B) is derived from 15 to 90 mol% of 4-methyl-1-pentene (excluding 4-methyl-1-pentene). Structural unit (i) and structural unit (ii) derived from 10-85 mol% α-olefin (however, the total of the proportion of structural unit (i) and the proportion of structural unit (ii) is 100 mol%) There is.)

  The proportion of the structural unit (i) derived from 4-methyl-1-pentene is preferably 20 to 80 mol%, more preferably 50 to 80 mol%, still more preferably 58 to 75 mol%. Particularly preferred is 60 to 75 mol%.

Further, the proportion of the structural unit (ii) derived from the α-olefin is preferably 20 to 80 mol%, more preferably 20 to 50 mol%, still more preferably 25 to 42 mol%, particularly Preferably it is 25-40 mol%.
When the proportion of the structural unit (i) is less than 15 mol%, the flexibility, lightness and vibration resistance are impaired, and when it exceeds 90 mol%, the vibration resistance, flexibility and lightness are impaired.

  Examples of the α-olefin that leads to the structural unit (ii) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, and 1-tetradecene. , 1-hexadecene, 1-octadecene, 1-eicosene and the like, a linear α-olefin having 2 to 20 carbon atoms, preferably 2 to 15 carbon atoms, more preferably 2 to 10 carbon atoms, 3- Methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, Examples thereof include branched α-olefins having 5 to 20 carbon atoms, preferably 5 to 15 carbon atoms, such as 4-ethyl-1-hexene and 3-ethyl-1-hexene. Among these, ethylene, propylene, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and propylene is particularly preferable.

  The 4-methyl-1-pentene / α-olefin copolymer (B) is derived from other monomers as long as it is a small amount (eg, 10 mol% or less) that does not impair the object of the present invention. A structural unit may be included. Specific examples of other monomers include ethylene, 1-pentene / α-olefin copolymer (B) in the case of 4-methyl-1-pentene / propylene copolymer. Butene, 1-hexene, 1-octene, 5-methyl-2-norbornene, tetracyclododecene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene and the like are preferable.

Requirement (b);
The intrinsic viscosity [η] of the 4-methyl-1-pentene / α-olefin copolymer (B) measured in decalin at 135 ° C. is in the range of 0.5 to 5.0 dL / g. The details of the measurement conditions and the like are as described in the column of Examples described later.
The intrinsic viscosity [η] is preferably 0.7 to 4.0 (dL / g), more preferably 0.7 to 3.5 (dL / g).

  As described later, when a hydrogen molecule is used in combination during the polymerization, the molecular weight can be controlled, and the intrinsic viscosity [η] can be adjusted freely from a low molecular weight body to a high molecular weight body.

  If the intrinsic viscosity [η] is less than 0.5 dL / g or exceeds 5.0 dL / g, the moldability may be impaired.

Requirement (c);
Ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the 4-methyl-1-pentene / α-olefin copolymer (B) measured by gel permeation chromatography (GPC) ( The molecular weight distribution (Mw / Mn) is in the range of 1.0 to 3.5. The details of the measurement conditions and the like are as described in the column of Examples described later.
The Mw / Mn is preferably 1.2 to 3.0, more preferably 1.5 to 2.5.

  If the Mw / Mn exceeds 3.5, the influence of the composition distribution and the low molecular weight polymer is concerned, resulting in poor vibration damping. In addition, it is disadvantageous in expressing the mechanical properties and moldability of the polymer, causing stickiness during molding and causing problems.

  The weight average molecular weight (Mw) of the 4-methyl-1-pentene / α-olefin copolymer (B) measured by gel permeation chromatography (GPC) is preferably 500 in terms of polystyrene. To 10,000,000, more preferably 1,000 to 5,000,000, and still more preferably 1,000 to 2,500,000.

Requirement (d);
The density (measured by ASTM D1505) of the 4-methyl-1-pentene / α-olefin copolymer (B) is in the range of 830 to 880 kg / m ³ . The details of the measurement conditions and the like are as described in the column of Examples described later.

Density of the 4-methyl-1-pentene · alpha-olefin copolymer (B) is preferably 830~870kg / m ^3, more preferably 830~860kg / m ^3, more preferably 830~855kg / m ³ It is.

The density can be adjusted by changing the comonomer composition ratio in producing the 4-methyl-1-pentene / α-olefin copolymer (B), and the copolymer (B) within the above range is It is preferably used for lightweight sealing materials.
Further, the 4-methyl-1-pentene / α-olefin copolymer (B) preferably satisfies the following requirements (e) and (f).

Requirement (e);
Measurement of dynamic viscoelasticity of the 4-methyl-1-pentene / α-olefin copolymer (B) in a temperature range of −40 ° C. to 150 ° C. at a frequency of 1 Hz (details of measurement conditions and the like will be described later). The maximum value of the loss tangent tan δ (hereinafter also referred to as “tan δ peak value”) obtained by performing the above is preferably 1.0 to 5.0, more preferably 1. 0.5 to 5.0, and more preferably 2.0 to 4.0.

  The temperature at which the value of tan δ becomes maximum is preferably −10 ° C. to 40 ° C., more preferably 0 ° C. to 40 ° C., and further preferably 5 ° C. to 40 ° C.

  The maximum value of tan δ can be controlled by the comonomer composition ratio of the 4-methyl-1-pentene / α-olefin copolymer (B), for example, 4-methyl-1-pentene in the copolymer (A). The requirement (e) can be satisfied by setting the content to 20 to 80 mol%.

  The method for producing the 4-methyl-1-pentene / α-olefin copolymer (B) according to the present invention is not particularly limited. For example, the application has already been filed by the present applicant and disclosed in Japanese Patent Application Laid-Open No. 2012-82388. It can be easily produced by employing the polymerization method described in the published specification.

≪Rubber composition≫
The rubber composition of the present invention comprises 10 to 100 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (B) having specific physical properties with respect to 100 parts by mass of the specific rubber component (A). , Preferably 20 to 80 parts by mass, more preferably 20 to 60 parts by mass, particularly preferably 20 parts by mass or more and less than 50 parts by mass. When the amount of the component (B) is less than 10 parts by mass, the stress relaxation property as the composition may not be sufficient, which is not preferable. When the amount of the component (B) exceeds 100 parts by mass, the rubber component ( Since the rubber elasticity inherent to A) may be lost, it is not preferable.

  In addition to the rubber component (A) and the 4-methyl-1-pentene / α-olefin copolymer (B), the rubber composition of the present invention has a softening material, a reinforcing material, You may contain a filler, a processing aid, an activator, a hygroscopic agent, resin, etc.

  The softening material can be appropriately selected depending on its use, and can be used alone or in combination of two or more. Specific examples of the softening material include process oils such as paraffin oil (for example, “Diana Process Oil PS-430” (trade name: manufactured by Idemitsu Kosan Co., Ltd.), lubricating oil, liquid paraffin, petroleum asphalt, petrolatum, and the like. Oil-based softeners such as coal tar and coal tar pitch; fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, soybean oil, and palm oil; beeswax, carnauba wax, and Waxes such as lanolin; fatty acids such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, and zinc laurate or salts thereof; naphthenic acid, pine oil, and rosin or derivatives thereof; terpene resins, petroleum resins , Atactic polypropylene, coumarone indene resin, etc. Synthetic polymer materials: ester softeners such as dioctyl phthalate, dioctyl adipate, and dioctyl sebacate; other microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, liquid thiocol, hydrocarbon synthetic lubricant, tall oil, and Sub (Factis) etc. are mentioned. Of these, petroleum-based softening materials are preferred, and process oils, particularly paraffin oil, are particularly preferred. The compounding quantity of a softening material is 5-150 mass parts with respect to 100 mass parts of rubber components (A), Preferably it is 10-120 mass parts, More preferably, it is 20-100 mass parts.

  As the reinforcing material, specifically, “Asahi # 55G” and “Asahi # 50HG” (trade name: manufactured by Asahi Carbon Co., Ltd.), “Seast (trade name)” series: SRF, GPF, FEF are commercially available. , MAF, HAF, ISAF, SAF, FT, MT, etc., carbon black (manufactured by Tokai Carbon Co., Ltd.), carbon black surface-treated with a silane coupling agent, etc., silica, activated calcium carbonate, fine talc, fine powder Silicic acid or the like can be used. Of these, carbon black of “Asahi # 55G”, “Asahi # 50HG”, “Seast HAF” is preferable.

As the filler, light calcium carbonate, heavy calcium carbonate, talc, clay and the like can be used. Of these, heavy calcium carbonate is preferred. As heavy calcium carbonate, commercially available “Whiteon SB” (trade name: Shiraishi Calcium Co., Ltd.) or the like can be used.
The compounding amount of the reinforcing material and the filler is usually 30 to 300 parts by mass, preferably 50 to 250 parts by mass, and more preferably 70 to 230 parts by mass with respect to 100 parts by mass of the rubber component (A).

  As processing aids, those generally blended into rubber as processing aids can be widely used. Specific examples include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate or esters. Of these, stearic acid is preferred. The processing aid can be appropriately blended in an amount of 10 parts by mass or less, preferably 8 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

  An activator can be suitably selected according to a use, and can be used individually or in mixture of 2 or more types. Specific examples of the activator include di-n-butylamine, dicyclohexylamine, monoelaanolamine, “Acting B” (trade name: manufactured by Yoshitsugu Pharmaceutical Co., Ltd.), “Acching SL” (trade name: Yoshitsugu Pharmaceutical Co., Ltd.) Amines such as diethylene glycol, polyethylene glycol (for example, “PEG # 4000” (manufactured by Lion Corporation)), lecithin, triarylate melitrate, zinc compounds of aliphatic and aromatic carboxylic acids (for example, “Struktol activator”). 73 ”,“ Struktol IB 531 ”and“ Struktol FA541 ”(trade name: manufactured by Schill &Seilacher)); zinc peroxide preparations such as“ ZEONET ZP ”(trade name: manufactured by Nippon Zeon Co., Ltd.) ; Octadecyltri Chill ammonium bromide, synthetic hydrotalcite, special quaternary ammonium compounds (for example, "Arquad 2HF" (trade name: manufactured by Lion Akzo Co., Ltd.)), and the like. Among these, polyethylene glycol (for example, “PEG # 4000” (manufactured by Lion Corporation)) and “Arcade 2HF” are preferable. The compounding quantity of an activator is 0.2-10 mass parts with respect to 100 mass parts of rubber components (A), Preferably it is 0.3-5 mass parts, More preferably, it is 0.5-4 mass parts.

  The hygroscopic agent can be appropriately selected depending on the application, and can be used alone or in combination of two or more. Specific examples of the hygroscopic agent include calcium oxide, silica gel, sodium sulfate, molecular sieve, zeolite, white carbon and the like. Of these, calcium oxide is preferred. The compounding amount of the hygroscopic agent is 0.5 to 15 parts by mass, preferably 1.0 to 12 parts by mass, and more preferably 1.0 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A).

  When the rubber composition of the present invention contains crosslinkable components, these components may be crosslinked. In the case of crosslinking, a vulcanizing agent is added to the crosslinkable component and kneaded.

  As the vulcanizing agent (crosslinking agent), a sulfur compound, an organic peroxide, a phenol resin, an oxime compound, or the like can be used.

  Examples of sulfur compounds include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dithiocarbamate, and the like. The sulfur compound is preferably sulfur or tetramethylthiuram disulfide, and is usually 0.3 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight, more preferably 100 parts by weight of the rubber component (A). Can be blended in an amount of 0.7 to 4.0 parts by mass.

  Examples of the organic peroxide include dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2, Examples include 5-diethyl-2,5-di (t-butylperoxy) hexyne-3, di-t-butylperoxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-dibutylhydroperoxide, etc. it can. Of these, dicumyl peroxide, di-t-butyl peroxide, and di-t-butylperoxy-3,3,5-trimethylcyclohexane are preferable. The compounding quantity of an organic peroxide is 0.001-0.05 mol normally with respect to 100 g of rubber components (A), Preferably it is 0.002-0.02 mol, More preferably, it is 0.005-0.015. Is a mole.

When a sulfur compound is used as the vulcanizing agent, it is preferable to use a vulcanization accelerator in combination. Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N, N′-diisopropyl-2-benzothiazole sulfenamide, 2-mercapto Benzothiazole (for example, “Suncellor M” (trade name: manufactured by Sanshin Chemical Industry Co., Ltd.)), 2- (4-morpholinodithio) benzothiazole (for example, “Noxeller MDB-P” (trade name: Sanshin) Chemical Industry Co., Ltd.)), 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl disulfide and other thiazoles; Gua such as diphenyl guanidine, triphenyl guanidine, diorthotolyl guanidine Nidin type; acetaldehyde-aniline condensate, butyraldehyde-aniline condensate, aldehyde amine type; imidazoline type such as 2-mercaptoimidazoline; thiourea type such as diethylthiourea, dibutylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, etc. Thiuram series: zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate (for example, “Suncellar PZ” (trade name: manufactured by Sanshin Chemical Co., Ltd.), “Suncellor BZ” (trade name: Sanshin Chemical Industries) Etc.), dithioates such as tellurium diethyldithiocarbamate; ethylenethiourea (for example, “Suncellor BUR” (trade name: manufactured by Sanshin Chemical Co., Ltd.), “Suncellor 22-C” (trade name: Shin Kagaku Kogyo Co., Ltd.)), thiourea type such as N, N′-diethylthiourea; xanthate type such as zinc dibutylxatogenate; other zinc white (for example, “META-Z102” (trade name: Inoue Lime Industry) Zinc oxide), etc.
The amount of these vulcanization accelerators is 0.1 to 20 parts by weight, preferably 0.2 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the rubber component (A). Part.

  When vulcanization is performed, a vulcanization aid can be further used. Vulcanization aids can be appropriately selected depending on the application, and can be used alone or in combination of two or more. Specific examples of the vulcanization aid include magnesium oxide and zinc white (for example, zinc oxide such as “META-Z102” (trade name: manufactured by Inoue Lime Industry Co., Ltd.)). The compounding quantity is 1-20 mass parts normally with respect to 100 mass parts of rubber components (A). As vulcanization aids, quinone dioximes such as p-quinonedioxime; acrylics such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; allyls such as diallyl phthalate and triallyl isocyanurate; other maleimides; Examples include divinylbenzene.

  The rubber composition of the present invention may be entirely or partially foamed. The foam may be a vulcanized foam. The rubber composition of the present invention can be effectively used as, for example, an automobile sponge-like seal product, particularly a weather strip, by forming at least a part thereof into a foam.

  When the rubber composition of the present invention is made into a foam, a foaming agent is added to the above components to cause foaming. Examples of the foaming agent include inorganic foaming agents such as sodium bicarbonate and sodium carbonate; nitroso compounds such as N, N′-dinitrosopentamethylenetetramine and N, N′-dinitrosoterephthalamide; azodicarbonamide and azobisiso Organic foaming agents such as azo compounds such as butyronitrile; hydrazide compounds such as benzenesulfonyl hydrazide and 4,4′-oxybis (benzenesulfonyl hydrazide); azide compounds such as calcium azide and 4,4′-diphenyldisulfonyl azide Can be mentioned.

  The compounding quantity of a foaming agent is 3-30 mass parts with respect to 100 mass parts of rubber components (A), Preferably it is 4-20 mass parts. As a foaming agent, for example, vinylol AC # 3M (trade name: Eiwa Kasei Kogyo Co., Ltd. Azodicarbonamide (abbreviated as ADCA)), vinylol AC # 3C-K2 (trade name: Eiwa Kasei Kogyo Co., Ltd.) are commercially available. Amide (abbreviation ADCA)), Cellmic C-2 (trade name: Sankyo Kasei Co., Ltd. Azodicarbonamide (abbreviation ADCA)), Neocerbon N # 1000M (trade name: Eiwa Kasei Kogyo Co., Ltd. 4,4'-oxybis (benzene) Sulfonyl hydrazide) (abbreviation OBSH)) and the like can be used.

  Moreover, you may use a foaming adjuvant with a foaming agent. Examples of the foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid, oxalic acid, and citric acid, salts thereof, urea, and derivatives thereof. The blending amount of the foaming aid is 0.1 to 5 parts by mass, preferably 0.3 to 4 parts by mass with respect to 100 parts by mass of the rubber component (A). As the foaming aid, for example, commercially available cell paste K5 (trade name: Eiwa Kasei Kogyo Co., Ltd. urea), FE-507 (trade name: Eiwa Kasei Kogyo Co., Ltd. baking soda) and the like can be used.

  When the rubber composition of the present invention is a vulcanized foam, the composition containing the above components, vulcanizing agent, foaming agent and the like is vulcanized and foamed. As an example of vulcanization foaming, there is a method of extruding the composition using an extruder mounted on a tubular die and forming it into a tubular shape. The obtained molded body is introduced into a vulcanizing tank simultaneously with molding, and heated, for example, at 230 ° C. for 5 minutes to perform crosslinking and foaming to obtain a tubular foam (sponge).

The rubber composition of the present invention may contain a thermoplastic resin as necessary. Examples of the thermoplastic resin include crystallized polyolefin resin, α-olefin copolymer, rosin resin, terpene resin, petroleum resin and the like.
Examples of rosin resins include natural rosin, polymerized rosin, modified rosin and rosin derivatives modified with maleic acid, fumaric acid, (meth) acrylic acid, and the like. Examples of the rosin derivative include the above-mentioned natural rosin, polymerized rosin or esterified product of modified rosin, phenol-modified product and esterified product thereof. Furthermore, these hydrogenated substances can also be mentioned.

  Examples of the terpene resin include resins composed of α-pinene, β-pinene, limonene, dipentene, terpene phenol, terpene alcohol, terpene aldehyde, etc., and α-pinene, β-pinene, limonene, dipentene, An aromatic modified terpene resin obtained by polymerizing an aromatic monomer may also be used. Moreover, these hydrogenated substances can also be mentioned.

  Examples of the petroleum resin include an aliphatic petroleum resin whose main raw material is a C5 fraction of tar naphtha, an aromatic petroleum resin whose main raw material is a C9 fraction, and a copolymer petroleum resin thereof. That is, C5 petroleum resin (resin obtained by polymerizing C5 fraction of naphtha cracked oil), C9 petroleum resin (resin obtained by polymerizing C9 fraction of naphtha cracked oil), C5C9 copolymerized petroleum resin (C5 fraction of naphtha cracked oil) And a co-polymer of C9 fraction), a coumarone indene resin containing styrenes, indenes, coumarone, other dicyclopentadiene, etc. of the tar naphtha fraction, p-tert-butylphenol and Examples thereof include alkylphenol resins typified by condensates of acetylene, xylene resins obtained by reacting o-xylene, p-xylene or m-xylene with formalin.

  One or more resins selected from the group consisting of rosin resins, terpene resins, and petroleum resins are preferably hydrogenated derivatives because they are excellent in weather resistance and discoloration resistance. The softening point of the resin by the ring and ball method is preferably in the range of 40 to 180 ° C. The number average molecular weight (Mn) molecular weight measured by GPC of the resin is preferably in the range of about 100 to 10,000. Commercial products may be used as one or more resins selected from the group consisting of rosin resins, terpene resins and petroleum resins.

The rubber composition of the present invention is mixed with a known mixing method, for example, a plastmill, a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, a kneader ruder or the like, or after mixing, a single screw extruder or a twin screw extruder. , Kneader, Banbury mixer, roll kneader and the like can be produced by melt kneading.
The rubber composition of the present invention preferably has the following physical properties.

(Y): The change ΔHA in the value of Shore A hardness (measured in the state of a press sheet having a thickness of 3 mm according to JIS K6253) defined by the following formula is 10 to 60, preferably 10 to 50, more preferably 15-40. When ΔHA of the rubber composition of the present invention satisfies such a range, it means that the stress absorption is excellent. For example, when the rubber composition of the present invention has a complicated uneven shape, Even when it is applied, the rubber elastic function inherently possessed by the diene rubber is exhibited while exhibiting a sealing effect excellent in liquid followability at room temperature.
ΔHA = (Shore A hardness value immediately after the start of pressing needle contact) − (Shore A hardness value 15 seconds after the start of pressing needle contact)

≪Usage≫
As described above, the rubber composition of the present invention is a lightweight material that realizes excellent vibration absorption characteristics without being complicated, and can be used for various applications. For example, it is suitable as a shock absorbing material, a cushioning material, a vibration absorbing material, etc., such as an automotive sealing material, a building sealing material, a railway vehicle sealing material, a ship sealing material and an aircraft sealing material containing the rubber composition of the present invention. Used for.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. The numerical value regarding the component in the following table | surface shows a mass part.

≪Measurement conditions etc.≫
The measurement conditions of the physical properties in the examples are as follows.

〔composition〕
The content (mol%) of 4-methyl-1-pentene and α-olefin in the copolymer was measured by ¹³ C-NMR. The measurement conditions are as follows.
Measurement device: Nuclear magnetic resonance apparatus (ECP500 type, manufactured by JEOL Ltd.)
-Observation nucleus: ¹³ C (125 MHz)
・ Sequence: Single pulse proton decoupling ・ Pulse width: 4.7 μsec (45 ° pulse)
・ Repetition time: 5.5 seconds ・ Accumulation frequency: 10,000 times or more ・ Solvent: o-dichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent ・ Sample concentration: 55 mg / 0.6 mL
・ Measurement temperature: 120 ℃
-Standard value of chemical shift: 27.50ppm

〔density〕
The density of the polymer was measured according to JIS K7112 (density gradient tube method). This density (kg / m ³ ) was used as an indicator of lightness.

[Melting point (Tm)]
The melting point (Tm) of the polymer was measured with a differential scanning calorimeter (DSC) using DSC220C manufactured by Seiko Instruments Inc. Samples 7-12 mg were sealed in an aluminum pan and heated from room temperature to 200 ° C. at 10 ° C./min. The sample was held at 200 ° C. for 5 minutes to completely melt and then cooled to −50 ° C. at 10 ° C./min. After 5 minutes at −50 ° C., the sample was heated again to 200 ° C. at 10 ° C./min. This peak temperature in the second heating (second time) was adopted as the melting point (Tm).

[Intrinsic viscosity]
The intrinsic viscosity [η] of the polymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device. Specifically, about 20 mg of the powdery copolymer was dissolved in 25 ml of decalin, and then the specific viscosity η _sp was measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After the decalin was diluted by adding 5ml to this decalin solution was measured and the specific viscosity eta _sp in the same manner as described above. This dilution operation was further repeated twice, and the value of η _sp / C when the concentration (C) was extrapolated to 0 was determined as the intrinsic viscosity [η] (unit: dl / g) (see the following formula 1) .
[Η] = lim (η _sp / C) (C → 0) Equation 1

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) of the polymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) are determined by gel permeation chromatography (GPC: Gel Permeation). It calculated by the standard polystyrene conversion method using Chromatography). The measurement conditions are as follows.
Measurement device: GPC (ALC / GPC 150-C plus type, differential refractometer detector integrated type, manufactured by Waters)
Column: 2 GMH6-HT (manufactured by Tosoh Corp.) and 2 GMH6-HTL (manufactured by Tosoh Corp.) are connected in series. Eluent: o-dichlorobenzene Column temperature: 140 ° C
・ Flow rate: 1.0 mL / min

〔specific gravity〕
A test piece of 20 mm × 20 mm was punched out from a press sheet described later and measured according to JIS K7112 (density gradient tube method).

[Shore A hardness]
In the measurement of Shore A hardness (based on JIS K6253), a press sheet having a thickness of 3 mm was used as a measurement sample, and the graduations were read immediately after the start of pressing contact and 15 seconds after the start of pressing contact. Furthermore, the change ΔHA of the Shore A hardness value defined by the following equation was obtained as follows.
ΔHA = (Shore hardness value immediately after start of pressing needle contact) − (Shore hardness value 15 seconds after start of pressing needle contact).

(Dynamic viscoelasticity)
A press sheet having a thickness of 2 mm was prepared, and a strip of 45 mm × 10 mm × 2 mm necessary for dynamic viscoelasticity measurement was cut out. Using a viscoelasticity measuring apparatus ARES (manufactured by TA Instruments JAPAN Inc.), the temperature dependence of the viscosity of each material was measured under the following measurement conditions. The ratio (G ″ / G ′: loss tangent) between the storage elastic modulus (G ′) and the loss elastic modulus (G ″) obtained by the measurement was defined as tan δ. When tan δ is plotted against temperature, an upwardly convex curve or peak is obtained, and the temperature at the peak apex is defined as the glass transition temperature, that is, tan δ−Tg, and the maximum value at that temperature is measured. When two or more peaks were observed per tan δ, both tan δ-Tg and the maximum value were recorded as the first and second peaks.
(Measurement condition)
Frequency: 1.0Hz
Temperature: -70 to 80 ° C
Ramp Rate: 4.0 ° C./min Strain: 0.5%

[Tensile test]
Using a No. 3 dumbbell conforming to JIS K6251 in which a press sheet having a thickness of 2 mm was punched into a dumbbell shape, the test temperature was 23 ° C., the tensile speed was 200 mm / min. The tensile elongation at break (EB), the tensile strength at break (TB), and the tensile modulus at 25% elongation (YM) were calculated.

[Loss factor]
The loss factor was measured with a cantilever method tester (manufactured by Ono Sokki Co., Ltd.) at 23 ° C. in accordance with JIS K7391. As a measurement sample, a press sheet having a thickness of 2 mm was punched into a width of 10 mm × 160 mm and pasted on a base layer made of SUS430, and vibration was performed by steady excitation using a non-contact electromagnetic vibrator. The loss factor of each material was calculated from the resonance frequency when the material vibrated.

≪Combination material≫
The compounding materials used in Examples and Comparative Examples are as follows.
(A) Rubber component (A-1) Acrylonitrile butadiene rubber (NBR) (trade name: Nipol 1042 (manufactured by Nippon Zeon Co., Ltd.), bound acrylonitrile amount: 33.5%, Mooney viscosity [ML _{1 + 4} (100 ° C. ]]: 77.5)
(A-2) Butyl rubber (IIR) (trade name: JSR Butyl 268 (manufactured by JSR Corporation), degree of unsaturation (mol%): 1.5%, Mooney viscosity [ML _{1 + 8} (125 ° C.)] : 51)
(A-3) Styrene butadiene rubber (SBR) (trade name: SBR 1502 (manufactured by Zeon Corporation), bound styrene content: 23.5%, Mooney viscosity [ML _{1 + 4} (100 ° C.)]: 52)
(A-4) Natural rubber (NR) (trade name: NR RSS-3)
(B) Copolymer (B-1) 4-methyl-1-pentene / propylene copolymer (P) obtained in Polymerization Example 1 below

[Polymerization Example 1]
A SUS autoclave with a stirring blade having a capacity of 1.5 liters sufficiently purged with nitrogen was charged with 300 ml of normal hexane at 23 ° C. (dried in a dry nitrogen atmosphere and activated alumina) and 450 ml of 4-methyl-1-pentene. . The autoclave was charged with 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL), and the stirrer was rotated.

  Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure was 0.40 MPa (gauge pressure). Subsequently, 1 mmol of methylaluminoxane prepared in advance, diphenylmethylene (1-ethyl-3-tert-butyl-cyclopentadienyl) (2,7-di-tert-butyl-fluorenyl) zirconium in terms of Al Polymerization was initiated by injecting 0.34 ml of a toluene solution containing 0.01 mmol of dichloride into the autoclave with nitrogen. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C. Sixty minutes after the start of polymerization, 5 ml of methanol was injected into the autoclave with nitrogen to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. Acetone was poured into the reaction solution with stirring.

  The obtained powdered polymer containing the solvent was dried at 100 ° C. under reduced pressure for 12 hours. The obtained polymer (P) was 36.9 g, the content of structural units derived from 4-methyl-1-pentene in the polymer was 72 mol%, and the content of structural units derived from propylene was 28 mol%. The weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) was 337,000, tan δ-Tg was 30 ° C., and the maximum tan δ was 2.7.

(B-2) Commercially available ethylene / α-olefin copolymer (trade name: TAFMER DF605 (manufactured by Mitsui Chemicals), tan δ-Tg is −46 ° C., tan δ maximum value is 0.5)
(C) Vulcanization aid (C-1) Two types of zinc oxide (Mitsui Metals Mining Co., Ltd.)
(I) Vulcanizing agent:
Sulfur (trade name: Alpha Grand S-50EN (manufactured by Tochi Co., Ltd.))
(J) Vulcanization accelerator:
(J-1) Thiuram-based vulcanization accelerator: Tetramethylthiuram disulfide (trade name: Sunseller TT (manufactured by Sanshin Chemical Industry Co., Ltd.))
(J-2) Sulfenamide vulcanization accelerator: N- (tert-butyl) -2-benzothiazole sulfenamide (trade name: Sunseller NS-G (manufactured by Sanshin Chemical Industry Co., Ltd.))

[Example 1]
Using an 8-inch two-roll kneader, the kneading conditions were: front roll / rear roll: 70 ° C./70° C., front roll rotation speed 12.5 rpm, rear roll rotation speed 10.4 rpm, rubber component (A- 1) Knead 100 parts by weight of NBR, 40 parts by weight of copolymer (P), 3 parts by weight of vulcanization aid (C-1) (zinc oxide), and 1 part by weight of processing aid (stearic acid) until uniform. Then, 0.7 parts by mass of vulcanization accelerator (J-2) (N- (tert-butyl) -2-benzothiazolesulfenamide) and 1.55 parts by mass of vulcanizing agent (sulfur) were added. Further kneading until uniform. Thereafter, the sheet was dispensed into a sheet and vulcanized by heating at 160 ° C. for 30 minutes using a heating press to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Example 2]
In Example 1, (A-2) IIR was used instead of rubber component (A-1) NBR, and vulcanization accelerator (J-2) (N- (tert-butyl) -2-benzothiazolesulfenamide was used. ) Example 1 except that 1 part by mass of vulcanization accelerator (J-1) (tetramethylthiuram disulfide) was used instead of 0.7 parts by mass and 1.75 parts by mass of vulcanizing agent (sulfur) was used. The same operation was performed to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Example 3]
In Example 1, (A-3) SBR was used instead of rubber component (A-1) NBR, and vulcanization accelerator (J-2) (N- (tert-butyl) -2-benzothiazolesulfenamide was used. ) And 175 parts by mass of vulcanizing agent (sulfur) were used, and the same operation as in Example 1 was performed to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Example 4]
In Example 1, (A-4) NR was used instead of rubber component (A-1) NBR, and vulcanization accelerator (J-2) (N- (tert-butyl) -2-benzothiazolesulfenamide was used. ) Was used in the same manner as in Example 1 except that 1 part by mass and 1.5 parts by mass of the vulcanizing agent (sulfur) were used to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, except that the copolymer (P) was not used, the same operation as in Example 1 was performed to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 2]
In Example 2, a vulcanized sheet (press sheet) having a thickness of 2 mm was obtained by performing the same operation as in Example 2 except that the copolymer (P) was not used. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 3]
In Example 3, except that the copolymer (P) was not used, the same operation as in Example 3 was performed to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 4]
In Example 4, except that the copolymer (P) was not used, the same operation as in Example 4 was performed to obtain a vulcanized sheet (press sheet) having a thickness of 2 mm. The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 5]
In Example 1, a vulcanized sheet (press sheet) having a thickness of 2 mm was obtained by performing the same operation as in Example 1 except that Tafmer DF605 was used instead of the copolymer (P). The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

[Comparative Example 6]
In Example 4, a vulcanized sheet (press sheet) having a thickness of 2 mm was obtained by performing the same operation as in Example 4 except that Tafmer DF605 was used instead of the copolymer (P). The above measurement and evaluation were performed using this vulcanized sheet. The results are shown in Table 1.

  As can be seen from Table 1, various rubbers (NBR, IIR, SBR, NR) are blended with 4-methyl-1-pentene / α-olefin copolymer (B1) that satisfies the specific requirements according to the present invention. Since the product satisfies the Shore A hardness change rate (ΔHA) in the range of 10 to 60, the stress relaxation property (unevenness follow-up property) is remarkably improved as compared with the rubber component (A) alone system. It is also clear that such stress relaxation properties cannot be achieved with existing ethylene copolymers (see Comparative Examples 5 and 6). Furthermore, it should be noted that in all the experimental examples, the specific gravity is reduced by the blending of the component (B1). Such a reduction in specific gravity leads to a reduction in the weight of the material.

  Moreover, from the measurement result of the loss coefficient representing vibration damping properties, the rubber composition containing the 4-methyl-1-pentene / α-olefin copolymer (B1) satisfying the specific requirements according to the present invention is particularly 1000 Hz or less. The loss factor on the low frequency side is improved. It has also been found that such damping properties cannot be achieved with existing ethylene copolymers.

  When IIR or SBR is used as the rubber, the result is that the strength at break is remarkably improved by blending the component (B1), or when NBR, IIR and SBR are used among the rubbers, the component (B1) is added. The fact that blending greatly improves not only the elastic modulus inherent in rubber but also the elongation at break was an unexpected result for the inventors. Although the reason about the improvement effect of the mechanical characteristics at the time of such tension | pulling is not clear at this time, this inventor found that a rubber component and 4-methyl-1- pentene-type copolymer (B1) as a result of a viscoelasticity measurement. Since two peaks derived from the above are observed, the rubber component and the 4-methyl-1-pentene copolymer (B1) are incompatible with each other, and have been confirmed separately as to hardly contribute to crosslinking. From the results, it is considered that the mechanical strength is probably improved by the microcrystallization of the component (B1) during elongation.

Claims (4)

For 100 parts by mass of rubber component (A) containing a conjugated diene monomer unit,
Rubber containing 10 to 100 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (B) satisfying the following requirements (a), (b), (c) and (d) Composition.
(A) From the structural unit (i) derived from 15 to 90 mol% of 4-methyl-1-pentene and 10 to 85 mol% of an α-olefin (excluding 4-methyl-1-pentene). The derived structural unit (ii) (however, the sum of the proportion of the structural unit (i) and the proportion of the structural unit (ii) is 100 mol%).
(B) The intrinsic viscosity [η] measured at 135 ° C. in decalin is in the range of 0.5 to 5.0 dL / g.
(C) The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) (molecular weight distribution; Mw / Mn) is in the range of 1.0 to 3.5. It is in.
(D) The density is in the range of 830 to 880 kg / m ³ .   The rubber composition according to claim 12, wherein the conjugated diene monomer is isoprene or butadiene.   The rubber component (A) containing the conjugated diene monomer unit comprises natural rubber (NR) and / or polyisoprene rubber (IR), butadiene-acrylonitrile copolymer (NBR), and styrene-butadiene copolymer. 3. The rubber composition according to claim 1, comprising at least one of (SBR) and an isobutylene-isoprene copolymer (IIR) as a main component.   The rubber composition according to claim 1, wherein the α-olefin is propylene.