JP5953776B2 - Anti-vibration rubber composition and anti-vibration rubber - Google Patents

Description

  The present invention relates to a rubber composition for vibration-proof rubber used for automobile engine mounts, muffler hangers, torsional dampers and the like.

  Anti-vibration rubber is placed in a site that is a source of vibration and noise to improve passenger comfort in various vehicles such as automobiles. The required performance is required to have low dynamic magnification, high heat resistance, ozone resistance, and high hysteresis loss. The dynamic magnification is a ratio between the dynamic elastic modulus and the static elastic modulus, and a low dynamic magnification is required as a basic characteristic of the vibration-proof rubber. In particular, in a high distortion region at a low frequency of about 10 to 20 Hz, high attenuation, that is, high hysteresis loss (tan δ) is required.

  Conventionally, it has been known to use chloroprene rubber (CR) as a main component of the rubber in order to improve the heat resistance of the vibration-proof rubber, but there is a drawback that the dynamic magnification is deteriorated. In order to prevent such a disadvantageous phenomenon, an anti-vibration rubber composition has been proposed in which the amount of filler such as carbon black blended with chloroprene rubber is small. However, in this case, the dynamic magnification can be reduced, but the hysteresis loss is reduced.

  It is also known that hysteresis loss can be increased by adding a predetermined amount of various synthetic resins to the rubber main component of the vibration-proof rubber composition. However, in this case, the dynamic magnification deteriorates.

  From the above, in the field of vibration proof rubber, it is difficult to achieve both high heat resistance and high loss and low dynamic ratio.

  In addition, the following patent documents are mentioned as a proposal of the vibration-proof rubber which uses chloroprene rubber as a main component of rubber.

JP-A-8-127673 JP 2001-131341 A JP 2009-24046 A

  The present invention has been made in view of the above circumstances, and provides an anti-vibration rubber composition having improved heat resistance, low dynamic magnification and high damping properties at the same time, and an anti-vibration rubber obtained by curing the rubber composition. For the purpose.

  As a result of intensive studies in order to achieve the above object, the present inventor has made chloroprene rubber as a main component, as necessary, as a selection of a rubber for improving heat resistance, and as necessary. When base oil blended with diene rubber is blended with a certain amount of C9 series alone or C9 series and C5 series petroleum-based resin, it reduces dynamic ratio and improves hysteresis loss (tan δ). It has been found that an anti-vibration rubber composition that can simultaneously improve the three properties of heat resistance, low dynamic magnification and high damping property is obtained, and the present invention has been made.

Accordingly, the present invention provides the following anti-vibration rubber composition and anti-vibration rubber.
[ 1 ] A rubber component mainly composed of chloroprene rubber or a mixture of chloroprene rubber and diene rubber, FEF-grade carbon black, and petroleum-based resin obtained by mixing C9 alone or C9 and C5 The chloroprene rubber (A) and the diene rubber (B) at a mass ratio of (A) / (B) = 100/0 to 50/50, An anti-vibration rubber composition characterized in that the amount is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.
[2] The anti-vibration rubber composition according to [1], wherein the petroleum resin has a melting point of 140 ° C. or higher.
[3] A vibration-proof rubber obtained by curing the rubber composition according to the above [1] or [2].

  According to the vibration-insulating rubber composition of the present invention, the three characteristics of heat resistance, low dynamic magnification and high damping can be improved at the same time.

  In the vibration-proof rubber composition of the present invention, as a rubber component, chloroprene rubber or a mixture of chloroprene rubber and diene rubber is used as a main component.

  Specifically, chloroprene rubber polymerizes 2-chloro-1,3-butadiene monomer or polymerizes monomer copolymerizable with 2-chloro-1,3-butadiene monomer. Can be obtained. As a known material, there is a specific trade name “Showprene WRT” (manufactured by Showa Denko). By using chloroprene as a main rubber component, at least heat resistance can be improved. Further, in the present invention, by blending each component described later, a rubber cross-linked molded article having excellent anti-vibration properties due to their synergistic effect. It is possible to obtain

  On the other hand, as the diene rubber, known rubbers can be used and are not particularly limited. Specifically, known natural rubber (NR), butadiene rubber, styrene-butadiene rubber (SBR). , Isoprene rubber, styrene-isoprene copolymer, butyl rubber, halogenated butyl rubber, isobutylene-isoprene rubber, acrylonitrile-butadiene rubber, epoxidized natural rubber, acrylate butadiene rubber and other synthetic rubber, and molecular chains of these natural rubber or synthetic rubber One having a modified end can be used, and one of these can be used alone, or two or more can be mixed and used. In the present invention, natural rubber, butadiene rubber, and styrene-butadiene rubber (SBR) can be preferably used.

  The blending ratio of the chloroprene rubber (A) and the diene rubber (B) is (A) / (b) = 100/0 to 50/50, preferably 100/0 to 60/40, more preferably, in mass ratio. Is 100/0 to 70/30. When the proportion of the diene rubber is too small than the above range, the dynamic magnification is increased, and when it is too large, the heat resistance may be lowered.

  In addition, rubbers other than the diene rubber can be blended in the rubber component as long as the effects of the present invention are not hindered. Examples of the rubber include acrylic rubber and ethylene-propylene-diene rubber (EPDM).

  As a vulcanizing agent, since chloroprene is used as a main rubber component in the present invention, chloroprene rubbers can be cross-linked using an ionic reaction using a metal oxide. Specifically, magnesium oxide, zinc oxide, or a combination thereof can be used as the metal oxide vulcanizing agent.

  Although depending on the type and amount of rubber such as diene rubber used in combination with chloroprene rubber, vulcanization using sulfur can be employed as auxiliary vulcanization.

The petroleum-based resin in which the C9 system alone or the C9 system and the C5 system are mixed will be described below.
The C5 system is an aliphatic petroleum resin in the C5 fraction obtained by naphtha cracking. Specifically, pentene (1), pentene contained in the C5 fraction obtained by naphtha pyrolysis is used. -(2), 2-methylbutene- (1), 3-methylbutene- (1), 2-methylbutene- (2) and other olefinic hydrocarbons, 2-methylbutadiene- (1,3), pentadiene- ( 1, 2), diolefin hydrocarbons such as pentadiene- (1,3) and 3-methylbutadiene- (1,2). In particular, in order to sufficiently obtain the effects of heat resistance, low dynamic magnification, and high attenuation, it is preferable to use a C5 petroleum resin having a melting point of 140 to 170 ° C.

  On the other hand, the C9 series is an aromatic petroleum resin in the C9 fraction obtained by naphtha cracking, specifically, α-methyl contained in the C9 fraction obtained by thermal decomposition of naphtha. Examples include vinyl-substituted aromatic hydrocarbons such as styrene, o-vinyltoluene, m-vinyltoluene, and p-vinyltoluene. In particular, in order to sufficiently obtain the effects of heat resistance, low dynamic magnification and high attenuation, it is preferable to use a C9 petroleum resin having a melting point of 140 to 170 ° C.

  Although the compounding quantity of said petroleum-type resin does not have a restriction | limiting in particular, It is suitable that it is 1-20 mass parts with respect to 100 mass parts of rubber components. If the blending amount of the petroleum resin is too large, a low dynamic magnification and a high damping property can be obtained, but the heat resistance may be deteriorated. On the other hand, if the blending amount of the petroleum resin is too small, heat resistance can be obtained satisfactorily, but the low dynamic magnification is deteriorated, and the hysteresis loss (tan δ) cannot be improved, so that sufficiently high attenuation is obtained. There is a risk of not.

  It is recommended that carbon black be blended as an inorganic reinforcing agent in the rubber composition. Carbon black imparts various reinforcing functions to rubber depending on the types such as average particle diameter, structure and surface properties. In the present invention, as the carbon black, known ones can be used, and are not particularly limited, but examples thereof include carbon blacks such as FEF, SRF, GPF, FT, MT, In particular, FEF can be suitably used. Moreover, these carbon blacks may be used individually by 1 type, and may use 2 or more types together. About the compounding quantity of carbon black, it is preferable that it is 10-80 mass parts with respect to 100 mass parts of said rubber components from the point of low dynamic magnification.

  Silica can also be blended as a filler, and the blending amount of silica used is preferably 10 to 80 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of reducing the dynamic ratio. .

  In the said rubber composition, vulcanization | cure acceleration | stimulation adjuvants, such as zinc white (ZnO) and a fatty acid, can be mix | blended from a viewpoint which accelerates | stimulates vulcanization | cure. In addition, the amount of active zinc white is less than that of normal zinc white, and since it is an ultrafine particle and has a very high activity, the action of vulcanization acceleration is strong. it can. The fatty acid may be saturated, unsaturated, linear or branched fatty acid, and is not particularly limited as the carbon number of the fatty acid. For example, the fatty acid has 1 to 30 carbon atoms, preferably 15 to 15 carbon atoms. 30 fatty acids, more specifically naphthenic acid such as cyclohexane acid (cyclohexanecarboxylic acid), alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid such as neodecanoic acid), Saturated fatty acids such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid), unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid, linolenic acid, resin acids such as rosin, tall oil acid, abietic acid, etc. Is mentioned. These may be used alone or in combination of two or more. In the present invention, zinc white and stearic acid can be preferably used. The compounding amount of these vulcanization acceleration aids is preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

  In addition, as the anti-aging agent, known ones can be used, and are not particularly limited, but examples thereof include a phenol-based anti-aging agent, an imidazole-based anti-aging agent, an amine-based anti-aging agent, and the like. Specific examples of the agent include styrenated difinylamine, N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6C), and the like. The blending amount of these anti-aging agents is usually 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

  As the oil, known oils can be used, and are not particularly limited. Specifically, process oils such as aromatic oils, naphthenic oils, paraffin oils, vegetable oils such as palm oil, alkylbenzene oils, etc. Synthetic oil, castor oil, etc. can be used. These can be used alone or in combination of two or more.

  In addition, waxes, antioxidants, fillers, foaming agents, plasticizers, oils, lubricants, which are usually used in the rubber industry, as necessary, as long as the effects of the present invention are not impaired. Additives such as tackifiers, petroleum resins other than those described above, ultraviolet absorbers, dispersants, compatibilizers, homogenizers, and the like can be appropriately blended.

  When obtaining the rubber composition having the above-described blending components, there is no particular limitation on the blending method of each of the above components, and all the component raw materials may be blended and kneaded at once, or divided into two or three stages. Each component may be blended and kneaded. In kneading, a 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, there are no particular limitations on the vulcanization conditions for curing the rubber composition, but vulcanization conditions can be generally employed at 140 to 180 ° C. for 5 to 120 minutes.

  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 1-6, Comparative Examples 1-7]
According to the rubber compounding composition shown in Table 1 below, each component is kneaded into kneading stages A and B in Table 1, and kneading stage A kneads the rubber component excluding the vulcanizing agent and vulcanization accelerator. The kneading stage B means a step of kneading a vulcanizing agent or a vulcanization accelerator with the rubber composition obtained in the kneading stage A.
As described above, each example and comparative example was kneaded and vulcanized at a temperature of 155 ° C. for 30 minutes to produce a sheet molded product. This molded sheet was used as an evaluation body for vibration-proof rubber.
And about the obtained rubber sheet, heat resistance (thermal aging test) hardness (Hd), dynamic magnification (Kd / Ks), and hysteresis loss (tan-delta) were measured and evaluated based on the following JIS specification. The results are shown in Table 1.

[Heat resistance (heat aging test)]
In accordance with JIS K 6257, the tensile elongation (Eb) before and after leaving the test piece under the conditions of 120 ° C. and 100 hours was measured, and the retention (%) of the tensile elongation (Eb) was examined.
[Dynamic magnification (Kd / Ks)]
Based on JIS K 6385, the static spring constant (Ks) and the dynamic spring constant (Kd) were measured, and the dynamic magnification (Kd / Ks) was examined. Kd was measured at 100 Hz.
[Tan δ / hysteresis loss]
Loss coefficient tan δ: measured in accordance with JIS K 6385 (15 Hz).

Details of the formulation in Table 1 are as follows.
(1) CR: Chloroprene rubber “Showprene WRT” (manufactured by Showa Denko)
(2) NR: Natural rubber “RSS # 1”
(3) Magnesium oxide: “Kyowa Mag 30” (manufactured by Kyowa Chemical)
(4) FEF: FEF grade carbon black: “Asahi # 65” (Asahi Carbon Co., Ltd.)
(5) Fatty acid: “Stearic acid 50S” (manufactured by Shin Nippon Science Co., Ltd.)
(6) Petroleum-based resin (melting point: 145 ° C.): “Nisseki Neopolymer 140” (manufactured by Nippon Petrochemical Co., Ltd.)
(7) Petroleum-based resin (melting point: 120 ° C.): “Nisseki Neopolymer 120” (manufactured by Nippon Petrochemical Co., Ltd.)
(8) Phenol resin: “Sumilite resin PR-50235” (manufactured by Sumitomo Bakelite)
(9) Dicyclopentadiene resin: “Marcaretz M-890A” (manufactured by Maruzen Petrochemical Co., Ltd.)
(10) DOP: Dioctyl phthalate (plasticizer) “Vinicizer 80K” (manufactured by Kao Corporation)
(11) Active zinc white: “AZO” (manufactured by Shodo Chemical Industry Co., Ltd.)
(12) Anti-aging agent 6C: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine “NOCRACK 6C” (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
(13) Sulfur: sulfur powder manufactured by Tsurumi Chemical Co., Ltd. (14) TT: tetramethylthiuram disulfide (TT) (manufactured by Ouchi Shinsei Chemical Co., Ltd.)

Claims (3)

A rubber component mainly composed of chloroprene rubber, or a mixture of chloroprene rubber and diene rubber, and FEF grade carbon black, and C9 series alone or a petroleum resin in which C9 series and C5 series are mixed. The chloroprene rubber (A) and the diene rubber (B) are contained in a mass ratio of (A) / (B) = 100/0 to 50/50, and the blending amount of the petroleum resin is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.   The anti-vibration rubber composition according to claim 1, wherein the petroleum resin has a melting point of 140 ° C or higher.   Anti-vibration rubber obtained by curing the rubber composition according to claim 1.