JP6609934B2 - Rubber composition for anti-vibration rubber and anti-vibration rubber - Google Patents

Description

  The present invention relates to a rubber composition for an anti-vibration rubber capable of obtaining an anti-vibration rubber having excellent heat resistance and anti-vibration performance, and an anti-vibration rubber obtained by curing the rubber composition.

  2. Description of the Related Art Conventionally, in various vehicles such as automobiles, various anti-vibration materials are attached to portions that are sources of vibration and noise in order to suppress noise and improve passenger comfort. For example, for engines that are the main sources of vibration and noise, vibrations during engine drive are absorbed by using anti-vibration rubber for components such as engine mounts and torsional dampers. Intrusion and noise diffusion to the surrounding environment.

  As a basic characteristic of such an anti-vibration rubber, a strength characteristic that supports a heavy object such as an engine and an anti-vibration performance that absorbs and suppresses the vibration are required. Furthermore, when used in a high temperature environment such as an engine room, it has excellent strength characteristics, low dynamic magnification and excellent vibration proofing performance, as well as heat resistance, durability and sag resistance. High is required. In particular, in recent years, the demand for automobiles in extremely hot regions has increased, and the engine compartment has become hotter due to the downsizing / high output of the engine and downsizing of the engine room. The demand for heat resistance is even more severe.

  In general, it is effective to add a bismaleimide compound to improve the heat resistance of rubber. For example, JP 2005-194501 A (Patent Document 1) describes a bismaleimide compound, a specific vulcanization accelerator, And an anti-vibration rubber composition that does not contain sulfur has been proposed.

  Thus, further improvement of the heat resistance and vibration proof performance of the vibration proof rubber is an important issue for use in the severe environment as described above.

JP 2005-194501 A

  The present invention has been made in view of the above circumstances, and a rubber composition for an anti-vibration rubber capable of obtaining an anti-vibration rubber excellent in heat resistance and anti-vibration performance, and an anti-vibration formed by curing the rubber composition. The object is to provide a vibration rubber.

  As a result of intensive studies to achieve the above object, the present inventor is excellent by curing a rubber composition containing a diene rubber, a bismaleimide compound, and zinc white having a specific specific surface area. It was found that a vibration-proof rubber having high heat resistance and vibration-proof performance (low dynamic magnification) can be obtained, and the present invention has been made.

［式中、ｘ及びｙはそれぞれ独立に０〜２０のいずれかの整数を示す。Ｒ¹は炭素数５〜１８の芳香族基、又はアルキレン基を含む炭素数７〜２４の芳香族基を示す。］
［４］上記ビスマレイミド化合物をジエン系ゴム１００質量部に対して０．１〜５質量部含有する［１］〜［３］のいずれかに記載の防振ゴム用ゴム組成物。
［５］さらに硫黄を含有してなる［１］〜［４］のいずれかに記載の防振ゴム用ゴム組成物。
［６］［１］〜［５］のいずれかに項記載の防振ゴム用ゴム組成物を硬化させてなる防振ゴム。
Accordingly, the present invention provides the following rubber composition for vibration-proof rubber and vibration-proof rubber.
[1] A vibration proof comprising a diene rubber, a bismaleimide compound, and zinc white having a nitrogen adsorption specific surface area of 5 m ² / g or more by BET method and an average particle diameter of 5 μm or more. Rubber composition for rubber.
[ 2 ] The rubber composition for an anti-vibration rubber according to [1], containing 1 to 10 parts by mass of the zinc white with respect to 100 parts by mass of the diene rubber.
[ 3 ] The rubber composition for vibration-proof rubber according to [1] or [2] , wherein the bismaleimide compound is represented by the following structural formula.

[Wherein, x and y each independently represents an integer of 0 to 20. R ¹ represents an aromatic group having 5 to 18 carbon atoms or an aromatic group having 7 to 24 carbon atoms including an alkylene group. ]
[ 4 ] The rubber composition for an anti-vibration rubber according to any one of [1] to [3], containing 0.1 to 5 parts by mass of the bismaleimide compound with respect to 100 parts by mass of the diene rubber.
[5] The rubber composition for vibration-proof rubber according to any one of [1] to [4], further containing sulfur.
[6] An anti-vibration rubber obtained by curing the rubber composition for an anti-vibration rubber according to any one of [1] to [5].

  The rubber composition for an anti-vibration rubber of the present invention can provide an anti-vibration rubber having excellent heat resistance and anti-vibration performance by vulcanization and curing.

  The rubber composition for vibration-proof rubber of the present invention contains a diene rubber, a bismaleimide compound, and zinc white having a specific specific surface area. Hereinafter, the components contained in the rubber composition for vibration-proof rubber of the present invention will be described.

  As the diene rubber, known rubber can be used, and is not particularly limited. Specifically, natural rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, styrene-isoprene copolymer are used. , Synthetic rubbers such as butyl rubber, halogenated butyl rubber, chloroprene rubber, isobutylene-isoprene rubber, acrylonitrile-butadiene rubber, epoxidized natural rubber, acrylate butadiene rubber, etc., and natural rubber or synthetic rubber whose molecular chain terminal has been modified, etc. Can be illustrated. In the present invention, natural rubber, butadiene rubber, and styrene-butadiene rubber can be suitably used. The said diene rubber can be used individually by 1 type or in combination of 2 or more types. In addition, although it does not restrict | limit in particular, when using together natural rubber and a diene type synthetic rubber, the compounding ratio (natural rubber / diene type synthetic rubber) is 100 / 0-50 / 50 by mass ratio. It is preferable to set it to 100/0 to 70/30, more preferably.

  Further, rubber components other than the rubber components exemplified above can be blended within a range not departing from the object of the present invention. Specific examples thereof include silicone rubber, acrylic rubber, ethylene-propylene-diene rubber, ethylene propylene rubber, urethane rubber, chlorosulfonated rubber, chlorinated polyethylene, epichlorohydrin rubber, synthetic rubber such as fluorine rubber, and molecules of these synthetic rubbers. Examples thereof include those having chain ends modified. In the present invention, one or more of these can be appropriately selected and used.

As the bismaleimide compound, known compounds can be used, and are not particularly limited. In the present invention, a bismaleimide compound represented by the following structural formula can be preferably used.

In the above formula, x and y each independently represent an integer of 0 to 20, more preferably an integer of 0 to 10. R ¹ represents an aromatic group having 5 to 18 carbon atoms or an aromatic group having 7 to 24 carbon atoms including an alkyl group, and examples thereof include an aromatic group having the following structure.

  Specific examples of the bismaleimide compound represented by the above structural formula include N, N′-o-phenylene bismaleimide, N, N′-m-phenylene bismaleimide, N, N′-p-phenylene bismaleimide, N , N ′-(4,4′-diphenylmethane) bismaleimide, 2,2-bis- [4- (4-maleimidophenoxy) phenyl] propane, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane Etc. can be illustrated. In the present invention, N, N′-m-phenylenebismaleimide and N, N ′-(4,4′-diphenylmethane) bismaleimide can be preferably used. The said bismaleimide compound can be used individually by 1 type or in combination of 2 or more types. The blending amount is not particularly limited, but is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the diene rubber. By setting the blend amount of the bismaleimide compound to be equal to or more than the lower limit of the above range, excellent heat resistance and an effect of lowering the dynamic magnification can be obtained. Moreover, mold release property improves by making the compounding quantity below the upper limit of the said range.

  In the rubber composition of the present invention, not only heat resistance but also workability (release property) can be improved by using the bismaleimide compound in combination with zinc white having a specific surface area described later. In particular, when the blending amount of the bismaleimide compound is within the above range, the molded product is less likely to stick to the mold during vulcanization molding, so that the releasability is further improved. Improvement in mold release makes it difficult to cause inconveniences such as defective take-out of molded products and seizure. Therefore, it is possible to improve the productivity of the vibration-proof rubber while fully utilizing the effect of improving the heat resistance of the bismaleimide compound. .

In the present invention, zinc oxide having a nitrogen adsorption specific surface area of 5 m ² / g or more by the BET method is used. Moreover, the preferable range of the specific surface area of the said zinc white is 5-100 m < ² > / g, More preferably, it is 5-70 m < ² > / g. When the zinc white has a specific surface area of less than 5 m ² / g, the effect of improving the heat resistance and the effect of reducing the dynamic magnification cannot be obtained. Although it does not restrict | limit especially as said zinc white, the active zinc white which has the specific surface area mentioned above, electroconductive zinc oxide, etc. can be used conveniently. In the present invention, the specific surface area means a nitrogen adsorption specific surface area measured by the BET method according to JIS K 6217-2.

  The average particle size of the zinc white is not particularly limited, but is preferably 5 μm or more, more preferably 5 to 20 μm, and still more preferably 6 to 10 μm. By setting the average particle size of zinc white within the above range, it is possible to obtain excellent heat resistance and an effect of lowering the dynamic magnification. In the present invention, the average particle diameter means a value observed with an electron microscope.

  Although the compounding quantity of the said zinc white is not restrict | limited in particular, Preferably it is 1-10 mass parts with respect to 100 mass parts of said diene rubbers, More preferably, it can be 2-5 mass parts. A sufficient crosslinking density can be obtained by setting the blending amount of the zinc white to be equal to or more than the lower limit of the above range. On the other hand, the breaking strength and breaking elongation can be improved by making the compounding quantity below the upper limit of the above range.

In the rubber composition of the present invention, the zinc adsorption having a nitrogen adsorption specific surface area of 5 m ² / g or more by the above BET method is used together with a conventional zinc flower (nitrogen adsorption specific surface area by the BET method of 5 m). (Zinc flower less than ² / g) may be used in combination. The blending amount of the normal zinc white is not particularly limited, but it is preferable that the total blending amount of all zinc flowers is in a range of 1 to 10 parts by mass with respect to 100 parts by mass of the diene rubber. .

  If necessary, the rubber composition of the present invention can be blended with a vulcanization accelerator, a vulcanization acceleration aid, a filler, oil, waxes, an anti-aging agent and the like. Hereinafter, each of these components will be described.

  As the vulcanization accelerator, CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), TBSI (Nt-butyl-2) -Sulfenamide vulcanization accelerators such as benzothiazylsulfenimide), guanidine vulcanization accelerators such as DPG (diphenylguanidine), TMTD (tetramethyldisulfide), TETD (tetraethylthiuram disulfide), TBTD Examples thereof include thiuram vulcanization accelerators such as (tetrabutylthiuram disulfide) and tetrabenzylthiuram disulfide, and zinc dialkyldithiophosphate. These may be used alone or in combination of two or more. Although the compounding quantity of a vulcanization accelerator is not restrict | limited in particular, It is preferable to set it as 0.1-10 mass parts with respect to 100 mass parts of said diene rubbers, More preferably, 0.3-5 masses Part.

  In the present invention, a fatty acid can be blended as a vulcanization acceleration aid. The fatty acid may be saturated, unsaturated, linear or branched. Also, the number of carbon atoms is not particularly limited, and for example, one having 1 to 30 carbon atoms, preferably 15 to 30 carbon atoms can be used. Specific examples of the fatty acid include cyclohexane acid (cyclohexanecarboxylic acid), naphthenic acid such as alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid such as neodecanoic acid), dodecane, and the like. Acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid) and other saturated fatty acids, methacrylic acid, oleic acid, linoleic acid, linolenic acid and other unsaturated fatty acids, rosin, tall oil acid, abietic acid and other resin acids Can be mentioned. These may be used alone or in combination of two or more. In the present invention, stearic acid can be preferably used. The blending amount of these vulcanization acceleration aids is not particularly limited, but is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the diene rubber. it can. By setting the blending amount of the vulcanization acceleration aid to be equal to or more than the lower limit of the above range, a good vulcanization rate can be obtained. On the other hand, the effect which makes favorable workability | operativity and dynamic magnification low can be acquired by making the compounding quantity below into the upper limit of the said range.

  Examples of the filler include inorganic fillers such as carbon black, silica, fine particle magnesium silicate, heavy calcium carbonate, magnesium carbonate, clay and talc, high styrene resin, coumarone indene resin, phenol resin, lignin, and modified melamine. Organic fillers such as resins and petroleum resins can be exemplified. These can be used individually by 1 type or in combination of 2 or more types. In the present invention, carbon black can be preferably used.

  The carbon black is not particularly limited, and examples thereof include known SRF, GPF, FEF, HAF, ISAF, SAF, FT, MT and the like. In the present invention, in particular, FEF And FT can be preferably used. Moreover, these carbon blacks may be used individually by 1 type, and may use 2 or more types together. The carbon black having an iodine adsorption amount of 10 to 70 mg / g and a DBP oil absorption amount of 30 to 180 ml / 100 g can be suitably used. In the present invention, a vibration proof rubber capable of obtaining a vibration proof rubber having excellent basic physical properties and vibration proof performance (low dynamic magnification) is obtained by selecting a particularly suitable iodine adsorption amount, DBP oil absorption amount and the like. A rubber composition for rubber can be obtained. The blending amount of the carbon black is not particularly limited, but is preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass with respect to 100 parts by mass of the diene rubber.

  As the oil, process oil such as aromatic oil, naphthenic oil, paraffin oil, vegetable oil such as palm oil, synthetic oil such as alkylbenzene oil, castor oil, and the like can be used. In the present invention, naphthenic oil can be suitably used. These can be used individually by 1 type or in combination of 2 or more types. The blending amount of these oils is not particularly limited, but is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the diene rubber. By setting the blending amount of the oil within the above range, good kneading workability can be obtained.

  Examples of waxes include waxes such as known paraffin wax and microcrystalline wax, and amide compounds such as stearic acid amide, oleic acid amide, and erucic acid amide. One kind is used alone, or two or more kinds are used in combination. be able to. In particular, in the present invention, paraffin wax and microcrystalline wax can be preferably used. These blendings can improve molding workability and ozone resistance. The blending amount is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

  As the anti-aging agent, a phenol-based anti-aging agent, an imidazole-based anti-aging agent, an amine-based anti-aging agent and the like can be used. In this invention, these anti-aging agents can be used individually by 1 type or in combination of 2 or more types. The blending amount of the anti-aging agent is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the diene rubber. be able to.

  In addition to the above-mentioned components, the rubber composition of the present invention contains, as necessary, commonly used antioxidants, plasticizers, lubricants, tackifiers, petroleum resins, ultraviolet absorbers, and dispersants. In addition, an appropriate amount of additives such as a compatibilizing agent, a homogenizing agent, and a vulcanization retarder can be blended.

  When obtaining the rubber composition of the present invention, there are no particular restrictions on the method of blending the above components, and all the components may be blended and kneaded at once, or the components may be blended in two or three stages. And kneading may be performed. For kneading, a known kneader such as a roll, an internal mixer or a Banbury rotor can be used. Furthermore, when forming into a sheet shape or a belt shape, a known molding machine such as an extrusion molding machine or a press machine may be used.

  Moreover, the vulcanization conditions for curing the rubber composition are not particularly limited, but conditions of 140 to 180 ° C. and 2 to 120 minutes can be generally employed.

  The rubber composition for an anti-vibration rubber of the present invention is an anti-vibration rubber used in a harsh environment where high heat resistance is required, particularly an anti-vibration rubber used in a high temperature part such as an engine mount or a torsional damper of an automobile. Although used suitably for the use of rubber | gum, it is not limited to these.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.

[Examples 1-9, Comparative Examples 1-3]
The components shown in Table 1 below were kneaded to obtain rubber compositions for vibration-proof rubber of Examples 1 to 9 and Comparative Examples 1 to 3. Each rubber composition obtained was vulcanized and cured under the conditions of 155 ° C. for 20 minutes, hardness (Hd), tensile elongation (Eb), tensile strength (Tb), modulus (Md), static spring constant ( Ks), dynamic magnification (dynamic spring constant (Kd) / static spring constant (Ks)) and heat resistance were evaluated according to the following JIS standards. In the evaluation of hardness (Hd), tensile elongation (Eb), tensile strength (Tb) and heat resistance, a sheet of length 120 mm × width 120 mm × thickness 2 mm was prepared from the above rubber composition, and from there Test pieces compliant with each JIS standard were prepared. Further, in the evaluation of the static spring constant (Ks) and the dynamic magnification (Kd / Ks), a columnar sample having a diameter of 30 mm and a height of 30 mm was produced.
Moreover, when producing the said sheet | seat, the state of the molded product and the metal mold | die was observed after mold removal, the presence or absence of the burning of a rubber | gum was confirmed, and workability was evaluated.
The evaluation results are shown in Table 1.

・ Hardness (Hd)
It measured based on JIS K 6253 (type A).
・ Tensile elongation (Eb)
It measured based on JISK6251.
・ Tensile strength (Tb)
It measured based on JISK6251.
・ Modulus (Md)
Based on JIS K 6251, 100% modulus (Md100) was measured.
Static spring constant (Ks) and dynamic magnification (dynamic spring constant (Kd) / static spring constant (Ks))
About the cylindrical sample produced above, the static spring constant (Ks) and the dynamic magnification (dynamic spring constant (Kd) / static spring constant (Ks)) were calculated in accordance with JIS K 6385. The vibration frequency was 100 Hz. The lower the dynamic magnification, the better the anti-vibration performance.
-Heat resistance A test piece for which the static spring constant (Ks) has been calculated in advance is subjected to heat treatment at 100 ° C. for 240 hours in accordance with JIS K 6257. The static spring constant (Ks) was calculated, and the rate of change of the static spring constant (Ks) before and after the heat treatment was calculated.
-Workability After removing the above-mentioned sheet, the state of the molded product and the mold was observed to confirm the presence or absence of rubber seizure, and the workability was evaluated according to the following criteria.
○: There was no rubber seizure.
Δ: Slight rubber seizure was observed.
X: Rubber was seized.

The details of each component shown in Table 1 are as follows.
・ Natural rubber: “RSS # 4”
Carbon black: FT grade carbon black “Asahi Thermal” manufactured by Asahi Carbon Co., iodine adsorption amount 27 mg / g, DBP oil absorption amount 28 ml / 100 g
・ Stearic acid: “Stearic acid 50S” manufactured by Shin Nippon Chemical Co., Ltd.
Zinc flower A: “Activated zinc flower” manufactured by Shodo Chemical Co., Ltd., specific surface area 50 m ² / g, average particle diameter 6.5 μm
Zinc flower B: “Conductive zinc 23K” manufactured by Hakusuitec Co., Ltd., specific surface area 7 m ² / g, average particle size 5.5 μm
-Zinc Hana C: “No. 3 Zinc Hana” manufactured by Hakusui Tech Co., Ltd., specific surface area 4 m ² / g, average particle size 0.9 μm
Zinc flower D: “baked zinc flower” manufactured by Hakusuitec Co., Ltd., specific surface area 0.1 m ² / g, average particle size 9 μm
・ Wax: “Suntite S” manufactured by Seiko Chemical Co., Ltd.
Anti-aging agent 6C: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Naphthenic oil: “SUNTHENE 4240” made by SUN REFING AND MARKETING COMPANY
・ Sulfur: “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
・ Bismaleimide: N, N'-m-phenylenebismaleimide, "Barunok PM" manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator TT: Thiuram-based vulcanization accelerator, “Noxeller TT” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator CZ: Sulfenamide vulcanization accelerator, “Noxeller CZ-G” manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

  From the results shown in Table 1, the rubber composition for vibration-proof rubber containing a diene rubber, a bismaleimide compound, and zinc white having a specific specific surface area is excellent in processability at the time of vulcanization molding, and the rubber composition It was confirmed that an anti-vibration rubber having excellent heat resistance can be obtained by vulcanizing the product.

Claims (6)

A rubber for anti-vibration rubber, comprising a diene rubber, a bismaleimide compound, and zinc oxide having a nitrogen adsorption specific surface area of 5 m ² / g or more by BET method and an average particle diameter of 5 μm or more. Composition. The rubber composition for anti-vibration rubber according to claim 1, wherein the zinc white is contained in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the diene rubber. The rubber composition for vibration-proof rubber according to claim 1 or 2, wherein the bismaleimide compound is represented by the following structural formula.

[Wherein, x and y each independently represents an integer of 0 to 20. R ¹ represents an aromatic group having 5 to 18 carbon atoms or an aromatic group having 7 to 24 carbon atoms including an alkylene group. ] The rubber composition for vibration-proof rubber according to any one of claims 1 to 3 , comprising 0.1 to 5 parts by mass of the bismaleimide compound with respect to 100 parts by mass of the diene rubber. Furthermore, the rubber composition for vibration-proof rubbers of any one of Claims 1-4 formed by containing sulfur.   An anti-vibration rubber obtained by curing the rubber composition for an anti-vibration rubber according to any one of claims 1 to 5.