JP2007231065A - Vibration-proof rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-proof rubber composition which enables a low dynamic-to-static modulus ratio without lowering compression set. <P>SOLUTION: The vibration-proof rubber composition comprises a diene rubber (A), a sulfur-based vulcanizing agent (B), and a zinc dialkylphosphonate (C) as essential components, and the compounding amount of the component (C) is 0.5-2.5 pts.wt. based on 100 pts.wt. component (A). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an anti-vibration rubber composition, and more particularly to an anti-vibration rubber composition used for an engine mount or the like for suppressing vibration support and an engine support function of an automobile or the like.

Conventionally, as an anti-vibration rubber composition, for example, a rubber material such as natural rubber or synthetic rubber to which a sulfur vulcanizing agent or a vulcanization accelerator is added has been used. These vibration-insulating rubber compositions are required to have a low dynamic magnification (lower dynamic magnification) as an important characteristic. And there exists the method of increasing hardness other than a reinforcing agent for the purpose of the characteristic improvement of this low dynamic magnification reduction. As one of the methods, a method of adding a large amount of a sulfur vulcanizing agent has been proposed (see, for example, Non-Patent Document 1).
Rubber Industry Handbook (4th edition), edited by Japan Rubber Association, January 20, 1994, p. 605-606

  As described above, the technique of adding a large amount of the sulfur vulcanizing agent can improve the dynamic ratio, but tends to deteriorate the compression set.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vibration-proof rubber composition capable of reducing the dynamic magnification without deteriorating compression set.

In order to achieve the above object, the anti-vibration rubber composition of the present invention comprises the following (A) to (C) as essential components, and the blending amount of the (C) component is 100 parts by weight of the (A) component. And 0.5 to 2.5 parts by weight.
(A) Diene rubber.
(B) Sulfur-based vulcanizing agent.
(C) Dialkylphosphonate zinc salt.

  That is, the present inventors have intensively studied in order to obtain a vibration-proof rubber composition capable of reducing the dynamic magnification without deteriorating the compression set. As a result, when a dialkyl phosphonate zinc salt (C component) is used in combination in a system in which diene rubber (component A) is vulcanized with a sulfur vulcanizing agent (component B), the dialkyl phosphonate zinc salt (component C) is It has been found that the diene rubber (component A), which is a vibration-proof rubber, acts as a vulcanization accelerator, and has reached the present invention. This is thought to be based on the following reasons. That is, since the dialkylphosphonate zinc salt (component C) has an effect of increasing the crosslinking efficiency, it increases the hardness without deteriorating the compression set as compared with the conventional method of adding a large amount of the sulfur vulcanizing agent. Is possible. As a result, the compounding amount of the reinforcing agent can be reduced as compared with the conventional one, and it is considered that the dynamic magnification can be reduced.

  Thus, in the vibration-proof rubber composition of the present invention, the dialkylphosphonate zinc salt (component C) acts as a vulcanization accelerator for the diene rubber (component A) which is a vibration-proof rubber. Compared with the conventional method of adding a large amount of sulfur vulcanizing agent, it is possible to increase the hardness without deteriorating the compression set. As a result, the compounding amount of the reinforcing agent can be reduced as compared with the conventional case, and an effect that a reduction in dynamic magnification can be achieved is obtained.

  Further, when the amount of the sulfur vulcanizing agent (component B) is 0.7 to 5 parts by weight with respect to 100 parts by weight of the diene rubber (component A), the compression set characteristics are deteriorated. Therefore, it is possible to reduce the dynamic magnification.

  Next, embodiments of the present invention will be described in detail.

  The anti-vibration rubber composition of the present invention can be obtained using a diene rubber (component A), a sulfur vulcanizing agent (component B), and a dialkylphosphonate zinc salt (component C).

  In this invention, the compounding quantity of the said dialkylphosphonate zinc salt (C component) is 0.5-2.5 parts with respect to 100 weight part (henceforth "part") of the said diene rubber (A component). This is the biggest feature.

  The diene rubber (component A) is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR). ), Ethylene-propylene-diene rubber (EPDM) and the like. These may be used alone or in combination of two or more. Among these, natural rubber is preferably used in terms of vibration proof performance and rubber physical properties (breaking strength / breaking elongation).

  Next, examples of the sulfur vulcanizing agent (B component) used together with the diene rubber (A component) include sulfur (powder sulfur, precipitated sulfur, insoluble sulfur) and the like. These may be used alone or in combination of two or more.

  The amount of the sulfur vulcanizing agent (component B) is preferably 0.5 to 7 parts, particularly preferably 0.7 to 5 parts, relative to 100 parts of the diene rubber (component A). That is, if the amount of sulfur (component B) is less than 0.5 parts, the crosslinking reactivity tends to be poor, and conversely if it exceeds 7 parts, the compression set characteristics tend to deteriorate. Because it is.

  Next, examples of the dialkylphosphonate zinc salt (C component) used together with the diene rubber (component A) and the sulfur vulcanizing agent (component B) include those represented by the following general formula (1). can give.

In the above general formula (1), as the alkyl group represented by R ^{1 to} R ⁴ , an alkyl group having 1 to 30 carbon atoms is used, preferably an alkyl group having 1 to 20 carbon atoms, particularly preferably a carbon number. 1 to 8 alkyl groups are used.

  Specific examples of the dialkylphosphonate zinc salt (component C) include Lubrizol 1395 (manufactured by Lubrizol), Renocure TP / G (manufactured by LANXESS), and the like.

  The blending amount of the dialkylphosphonate zinc salt (component C) needs to be set to 0.5 to 2.5 parts, preferably 0.5 to 1 with respect to 100 parts of the diene rubber (component A). 3 parts. That is, if the dialkylphosphonate zinc salt (component C) is less than 0.5 part, the effect of increasing the hardness is insufficient, and conversely if it exceeds 2.5 parts, the physical properties deteriorate.

  In addition, in the vibration-proof rubber composition of the present invention, a reinforcing agent, a vulcanization accelerator, a vulcanization aid, an anti-aging agent, a process oil, and the like may be appropriately blended together with the components A to C as necessary. Is possible.

  Examples of the reinforcing agent include carbon black, silica, clay, talc and the like.

  The carbon black is not particularly limited, and examples thereof include various grades of carbon black such as SAF class, ISAF class, HAF class, MAF class, FEF class, GPF class, SRF class, FT class, and MT class. . These may be used alone or in combination of two or more. Among these, FEF grade carbon black is preferably used from the viewpoints of cost, durability, and the like.

  Further, the amount of the reinforcing agent such as carbon black is preferably 100 parts or less, particularly preferably 30 to 80 parts, per 100 parts of diene rubber (component A). That is, when the compounding amount of the reinforcing agent such as carbon black exceeds 100 parts, the Mooney viscosity increases and the workability tends to deteriorate.

  The vulcanization accelerator is not particularly limited, and examples thereof include thiazole type, sulfenamide type, aldehyde ammonia type, aldehyde amine type, guanidine type, thiourea type vulcanization accelerators. These may be used alone or in combination of two or more. Among these, a sulfenamide-based vulcanization accelerator is preferable from the viewpoint of excellent crosslinking reactivity.

  Further, the blending amount of the vulcanization accelerator is preferably 0.5 to 7 parts, particularly preferably 0.5 to 5 parts, relative to 100 parts of the diene rubber (component A).

  Examples of the thiazole vulcanization accelerator include dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazole sodium salt (NaMBT), and 2-mercaptobenzothiazole zinc salt (ZnMBT). Etc. These may be used alone or in combination of two or more. Among these, dibenzothiazyl disulfide (MBTS) and 2-mercaptobenzothiazole (MBT) are preferably used because they are particularly excellent in crosslinking reactivity.

  Examples of the sulfenamide-based vulcanization accelerator include N-oxydiethylene-2-benzothiazolylsulfenamide (NOBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and Nt. -Butyl-2-benzothiazoylsulfenamide (BBS), N, N'-dicyclohexyl-2-benzothiazoylsulfenamide and the like.

  The vulcanization aid is not particularly limited, and examples thereof include zinc white (ZnO), stearic acid, magnesium oxide and the like. These may be used alone or in combination of two or more.

  Further, the amount of the vulcanization aid is preferably 1 to 25 parts, particularly preferably 3 to 10 parts, relative to 100 parts of the diene rubber (component A).

  Examples of the anti-aging agent include carbamate-based anti-aging agents, phenylenediamine-based anti-aging agents, phenol-based anti-aging agents, diphenylamine-based anti-aging agents, quinoline-based anti-aging agents, imidazole-based anti-aging agents, and waxes. can give. These may be used alone or in combination of two or more.

  Further, the blending amount of the anti-aging agent is preferably 1 to 10 parts, particularly preferably 2 to 5 parts with respect to 100 parts of the diene rubber (component A).

  Examples of the process oil include naphthenic oil, paraffinic oil, and aroma oil. These may be used alone or in combination of two or more.

  The amount of the process oil is preferably 1 to 50 parts, particularly preferably 3 to 30 parts, per 100 parts of the diene rubber (component A).

  The anti-vibration rubber composition of the present invention can be prepared, for example, as follows. That is, in the diene rubber (component A), a reinforcing agent such as carbon black, a vulcanization aid, an anti-aging agent, a process oil and the like are appropriately blended as necessary, and these are used using a Banbury mixer or the like. Kneading is started from a temperature of about 50 ° C., and kneading is performed at 100 to 130 ° C. for about 3 to 5 minutes. Next, a dialkylphosphonate zinc salt (component C), a sulfur-based vulcanizing agent (component B), and a vulcanization accelerator, if necessary, are appropriately blended in this, and an open roll is used for predetermined conditions. An anti-vibration rubber composition is prepared by kneading (for example, 50 ° C. × 4 minutes). Next, by subjecting the obtained anti-vibration rubber composition to press vulcanization or the like under predetermined conditions, the target anti-vibration rubber can be obtained.

  The anti-vibration rubber composition of the present invention is suitably used as an anti-vibration material for engine mounts, stabilizer bushes, suspension bushes and the like used in automobile vehicles, for example.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.

  First, prior to the examples and comparative examples, the following materials were prepared.

[Diene rubber (component A)]
Natural rubber (RSS # 3)

[Vulcanization aid]
Zinc oxide (made by Sakai Chemical Industry Co., Ltd., 2 types of zinc oxide)

[Vulcanization aid]
Stearic acid (manufactured by Kao Corporation, Lunac S30)

[Anti-aging agent (6PPD)]
N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (manufactured by Seiko Chemical Co., Ltd., Ozonon 6C)

[Anti-aging agent (WAX)]
Special wax-based anti-aging agent (Sannok, Ouchi Shinsei Chemical Co., Ltd.)

〔Carbon black〕
FEF grade carbon black (manufactured by Tokai Carbon Co., Seast SO)

[Process oil]
Naphthenic process oil (Sansen 410 from Nippon San Oil Co., Ltd.)

[Vulcanization accelerator (CZ)]
N-cyclohexyl-2-benzothiazolylsulfenamide (Ouchi Shinsei Chemical Co., Ltd., Noxeller CZ-G)

[Dialkylphosphonate zinc salt (component C)]
Dialkylphosphonate zinc salt represented by the general formula (1) (Lubrisol 1395, manufactured by Lubrizol)

[Vulcanizing agent (component B)]
Sulfur (manufactured by Tsurumi Chemical Co., Ltd., gold crushed sulfur)

[Example 1]
100 parts of natural rubber that is a diene rubber (component A), 5 parts of zinc oxide that is a vulcanization aid, 1 part of stearic acid that is a vulcanization aid, 1 part of an anti-aging agent (6PPD), and aging 1 part of inhibitor (WAX), 30 parts of carbon black and 5 parts of process oil were blended, and these were kneaded from a temperature of about 50 ° C. using a Banbury mixer, and the maximum temperature (180 ° C.) And kneading for 4 minutes. Next, 0.50 part of dialkylphosphonate zinc salt, 1 part of vulcanization accelerator (CZ), and 2 parts of sulfur as the vulcanizing agent (component B) are blended into this, and an open roll is used. A rubber composition was prepared by kneading at about 50 ° C. for 4 minutes.

[Examples 2 to 5, Comparative Examples 1 to 4]
As shown in Table 1 and Table 2 below, a rubber composition was prepared according to Example 1 except that the amount of each component was changed.

  Using the rubber compositions of Examples and Comparative Examples thus obtained, each characteristic was evaluated according to the following criteria. These results are shown in Tables 1 and 2 above.

[Tensile properties]
Each rubber composition was press-molded under the conditions of 150 ° C. × 20 minutes and punched with a JIS No. 5 dumbbell to prepare a rubber sheet having a thickness of 2 mm. Then, using this rubber sheet, the breaking strength (TB), breaking elongation (EB), and hardness (Hs: JIS A) were measured according to JIS K 6251.

(Dynamic characteristics)
(Static spring constant: Ks)
Each rubber composition was press vulcanized under vulcanization conditions at 170 ° C. for 30 minutes to prepare a vulcanized rubber sample having a cylindrical shape (diameter 50 mm, height 25 mm). A test piece was prepared by adhering a pair of disk-shaped metal fittings (diameter 60 mm, thickness 6 mm) to the lower surface with an adhesive. Next, the test piece was compressed 7 mm in the cylinder axis direction, and the static spring constant (Ks) was calculated by reading the load at the time of deflection of 1.5 mm and 3.5 mm from the load deflection curve of the second round. .

(Dynamic spring constant: Kd)
The test piece is compressed 2.5 mm in the direction of the cylinder axis, and a constant displacement harmonic compression vibration with an amplitude of 0.05 mm is applied at a frequency of 100 Hz from the bottom, centered on the position of this 2.5 mm compression, and moved by an upper load cell. The dynamic spring constant (Kd) was calculated and measured according to JIS K 6394.

(Dynamic magnification: Kd / Ks)
The dynamic magnification was obtained as a value of dynamic spring constant (Kd) / static spring constant (Ks).

[Compression set (sag resistance)]
Each rubber composition was press vulcanized under the conditions of 160 ° C. × 15 minutes to prepare a cylindrical vulcanized rubber sample (diameter 29 mm, height 12.5 mm). Then, using this vulcanized rubber sample, compression set was measured in accordance with JIS K 6262 under the conditions of a temperature of 85 ° C., a test time of 72 hours, and a compression rate of 25%.

  From the results of Table 1 and Table 2, when the product of Example 1 and the product of Comparative Example 1 are compared, both have substantially the same static spring constant (Ks), but the product of Example 1 contains a dialkylphosphonate zinc salt. By blending, the blending amount of carbon black can be significantly reduced as compared with the one in Comparative Example, so that a low dynamic magnification effect of about 14% was obtained and the compression set characteristics were also improved. When the product of Example 2 and the product of Comparative Example 2 are compared with each other, both have substantially the same static spring constant (Ks), but the product of Example 2 contains a dialkylphosphonate zinc salt, so that the blending amount of carbon black is increased. Therefore, the low dynamic magnification effect of about 24% was obtained, and the compression set characteristics were also improved. When comparing the product of Example 3 with the product of Comparative Example 3, the static spring constant (Ks) and the dynamic magnification are both approximately equal, but the product of Example 3 is blended with a dialkylphosphonate zinc salt. Since the compounding amount of sulfur can be made smaller than that of Comparative Example 3, the compression set characteristics were improved.

  Moreover, when Example 4 goods and Example 1 goods are contrasted, although Example 4 goods are reducing the compounding quantity of sulfur rather than Example 1 goods, both compression set characteristics and tensile physical properties will deteriorate remarkably. The dynamic characteristics were also good. When the product of Example 5 and the product of Example 2 are compared, the product of Example 5 has an increased amount of sulfur as compared with the product of Example 2, but both the compression set characteristics and the tensile properties are not significantly deteriorated. The dynamic characteristics were also good.

  The anti-vibration rubber composition of the present invention is suitably used as an anti-vibration material for engine mounts, stabilizer bushes, suspension bushes and the like used in automobile vehicles.

Claims (3)

The following (A) to (C) are essential components, and the blending amount of the (C) component is 0.5 to 2.5 parts by weight with respect to 100 parts by weight of the (A) component. Rubber composition.
(A) Diene rubber.
(B) Sulfur-based vulcanizing agent.
(C) Dialkylphosphonate zinc salt.   The anti-vibration rubber composition according to claim 1, wherein the blending amount of the component (B) is 0.7 to 5 parts by weight with respect to 100 parts by weight of the component (A). The anti-vibration rubber composition according to claim 1 or 2, wherein the dialkylphosphonate zinc salt of the component (C) is represented by the following general formula (1).