Rubber composition and vibration-proof rubber

Abstract

To achieve both improved ride comfort and enhanced handling stability by improving tensile modulus.SOLUTION: There is provided a rubber composition which comprises a millable urethane polymer, an organic peroxide crosslinking agent and carbon having a nitrogen surface area of 30 m2 / g or more and 100 m2 / g or less, wherein the Mooney viscosity ML(1+4) at 100°C of the millable urethane polymer is 29 or more and 90 or less, the content ratio of the organic peroxide crosslinking agent is 2 pts.mass or more and 4 pts.mass or less based on 100 pt.mass of the millable urethane polymer and the content ratio of the carbon is 1 pt.mass or more and 40 pts.mass or less based on 100 pts.mass of the millable urethane polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rubber composition and a rubber vibration isolator. [Background technology]

[0002] Vehicles are equipped with a suspension system that connects the vehicle body and the wheels to press the wheels against the road surface and cushion the transmission of vibrations from the wheels to the vehicle body while traveling. Of the components that make up the suspension system, suspension bushings are required to have a vibration absorption function.

[0003] Conventionally, natural rubber has been widely used for suspension bushings because it is low cost, easy to mold, and readily available. However, natural rubber itself does not have enough hardness to support the vehicle body, so natural rubber cannot be used directly for suspension bushings.

[0004] For this reason, natural rubber materials in which carbon is added as a reinforcing material to natural rubber are used as vibration-isolating rubber for suspension bushings (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-96769 Summary of the Invention [Problem to be solved by the invention]

[0006] However, carbon inhibits the elongation and contraction of natural and synthetic rubber, so the tensile modulus of natural and synthetic rubber decreases as the carbon content increases.

[0007] Therefore, one possible way to improve ride comfort is to reduce the carbon content in the rubber for the suspension bushings. However, if the carbon content is reduced too much, it can cause delays in starting the steering when turning and increase the movement of the vehicle body, which can worsen stability, resulting in problems such as reduced ride comfort and handling stability.

[0008] Therefore, there is a demand for the development of a rubber composition that can achieve both improved ride comfort and improved handling stability.

[0009] In view of the above problems, the present invention aims to provide a rubber composition and an anti-vibration rubber that can improve both ride comfort and handling stability by improving the tensile modulus. [Means for solving the problem]

[0010] In order to solve the above problems, a rubber composition according to one embodiment of the present invention comprises: Millable urethane polymer, an organic peroxide crosslinking agent; Nitrogen surface area is 30m 2 / g or more 100m 2 / g or less of carbon, Equipped with The millable urethane polymer has a Mooney viscosity ML(1+4)100°C of 29 or more and 90 or less, The content of the organic peroxide crosslinking agent is 2 parts by mass or more and 4 parts by mass or less relative to 100 parts by mass of the millable urethane polymer, The content of the carbon is 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the millable urethane polymer. [Effects of the Invention]

[0011] According to the present invention, by improving the tensile modulus, it is possible to achieve both improved ride comfort and improved handling stability. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a graph showing the measurement results of the tensile modulus [MPa] of Examples 1 to 6 and the Comparative Example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0014] [Rubber composition] The rubber composition according to the present embodiment contains a millable urethane polymer, an organic peroxide crosslinking agent, and carbon.

[0015] <Millable Urethane Polymer> Millable urethane polymers are also called millable urethane rubbers. Millable urethane polymers are polymers with urethane bonds in their molecules. Millable urethane polymers can be, for example, various millable urethane polymers whose properties before curing are similar to those of ordinary uncrosslinked rubber and which can be plasticized and kneaded in a roll mill or kneader, or extrusion molded.

[0016] Millable urethane polymers are synthesized by reacting a polyol component, an isocyanate component, and optionally a chain transfer agent. The polyol component may be, for example, a polyester, polyether, polycarbonate, or polyolefin component.

[0017] The Mooney viscosity ML(1+4)100°C of the millable urethane polymer according to this embodiment is 29 or more and 90 or less, preferably 53 or more and 78 or less, more preferably 61 or more and 71 or less, and even more preferably 66.

[0018] Mooney viscosity ML(1+4)100°C is specified in JIS K6300-1. Mooney viscosity ML(1+4)100°C is the Mooney viscosity measured under the following conditions: test temperature 100°C, L-shaped rotor, preheating time 1 minute, rotor rotation time 4 minutes.

[0019] As the millable urethane polymer according to this embodiment, for example, either one or both of the product name "E8010" manufactured by Eikos Corporation and the product name "Iron Rubber" manufactured by NOK Corporation can be used.

[0020] <Organic peroxide crosslinking agent> An example of an organic peroxide crosslinking agent is bis(1-methyl-1-phenylethyl) peroxide.

[0021] The content of the organic peroxide crosslinking agent in the rubber composition is 2 to 4 parts by mass, preferably 2.5 to 3.5 parts by mass, more preferably 2.6 to 3.2 parts by mass, and even more preferably 2.8 parts by mass, per 100 parts by mass of the millable urethane polymer.

[0022] <Carbon> The carbon is, for example, carbon black. The carbon according to this embodiment has a nitrogen surface area of ​​30 m 2 / g or more 100m 2 / g or less. Here, the nitrogen surface area is a representative value obtained by the multipoint method.

[0023] In this embodiment, the carbon may include a first carbon and a second carbon having a different nitrogen surface area from the first carbon, or may consist of only the first carbon and the second carbon.

[0024] The nitrogen surface area of ​​the first carbon is, for example, 30 m 2 / g or more 50m 2 The nitrogen surface area of ​​the second carbon is, for example, 70 m2 / g or more 90m 2 / g or less.

[0025] The content ratio of the first carbon and the second carbon in the carbon contained in the rubber composition may be equal to or different from each other. For example, the content ratio of the first carbon in the carbon contained in the rubber composition may be higher than the content ratio of the second carbon.

[0026] The carbon content in the rubber composition is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of millable urethane polymer, preferably 20 parts by mass or more and 40 parts by mass or less, more preferably 30 parts by mass or more and 38 parts by mass or less, and even more preferably 34 parts by mass.

[0027] <Other> In addition to the millable urethane polymer, organic peroxide crosslinking agent, and carbon, the rubber composition may contain other additives, such as plasticizers, hydrolysis inhibitors, antioxidants, chemical dispersants, lubricants, and accelerators, as needed.

[0028] [Effects of rubber composition] The effects of the rubber composition according to the embodiment of the present invention will be described.

[0029] In conventional natural rubber materials, hardness is improved by increasing the carbon content. However, as the carbon content increases, the tensile modulus of the natural rubber material decreases. In other words, there is a trade-off between the carbon content and the tensile modulus. Therefore, conventional natural rubber materials have the problem of being unable to achieve both improved hardness and improved tensile modulus.

[0030] Therefore, the rubber composition according to the present embodiment is a rubber composition containing millable urethane polymer, an organic peroxide crosslinking agent, and a rubber composition having a nitrogen surface area of ​​30 m 2 / g or more 100m 2 / g or less of carbon, and the millable urethane polymer has a Mooney viscosity ML(1+4)100°C of 29 or more and 90 or less, the content of the organic peroxide crosslinking agent is 2 parts by mass or more and 4 parts by mass or less per 100 parts by mass of the millable urethane polymer, and the content of the carbon is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the millable urethane polymer.

[0031] As described above, the rubber composition according to this embodiment contains a millable urethane polymer having a Mooney viscosity ML(1+4)100°C of 29 to 90, and carbon, with the carbon content being 1 to 40 parts by mass per 100 parts by mass of the millable urethane polymer. This allows the rubber obtained by crosslinking the rubber composition according to this embodiment to have an improved tensile modulus. The tensile modulus is defined by JIS K6251.

[0032] The rubber composition according to this embodiment contains a millable urethane polymer having a Mooney viscosity ML(1+4)100°C of 29 to 90, and an organic peroxide crosslinking agent, with the content of the organic peroxide crosslinking agent being 2 to 4 parts by mass per 100 parts by mass of the millable urethane polymer. This allows the millable urethane polymer to be crosslinked well, and improves the hardness of the rubber obtained by crosslinking the rubber composition according to this embodiment.

[0033] Therefore, the rubber composition according to this embodiment can improve both the tensile modulus and hardness of the rubber after crosslinking.

[0034] The millable urethane polymer contained in the rubber composition according to the present embodiment may have a Mooney viscosity ML(1+4)100°C of 53 or more and 78 or less, which can further improve the tensile modulus [MPa].

[0035] The carbon contained in the rubber composition according to this embodiment may include a first carbon and a second carbon having a nitrogen surface area different from that of the first carbon, thereby reducing wear of the rubber composition.

[0036] The nitrogen surface area of ​​the first carbon contained in the rubber composition according to this embodiment is 30 m 2 / g or more 50m 2 / g or less, and the nitrogen surface area of ​​the second carbon is 70 m 2 / g or more 90m 2 / g or less, which can further reduce the wear of the rubber composition.

[0037] The rubber obtained by crosslinking the rubber composition according to this embodiment can be used in anti-vibration rubber. For example, the rubber composition according to this embodiment may be used in anti-vibration rubber for suspension bushings. The tensile modulus contributes to improving the ride comfort and handling stability of a vehicle. Therefore, by using the rubber composition according to this embodiment in anti-vibration rubber for suspension bushings, it is possible to achieve both improved ride comfort and improved handling stability, whether traveling straight or on a curve.

[0038] Furthermore, the articles to which the anti-vibration rubber is applied are not limited to the above-mentioned suspension bushings. For example, the anti-vibration rubber according to this embodiment can be applied to various articles such as muffler hangers used in automobile vehicles, etc. [Example]

[0039] Examples of the present invention and comparative examples will be specifically described below. Note that the examples shown below are merely examples, and the rubber composition according to the present invention is not limited to the following examples.

[0040] Rubber compositions were prepared for Examples 1 to 6. The compositions of Examples 1 to 6 are shown in Table 1 below.

[0041] [Table 1]

[0042] As shown in Table 1 above, in Examples 1 to 6, the content of the first carbon in the rubber composition was 18 parts by mass per 100 parts by mass of millable urethane polymer. Also, in Examples 1 to 6, the content of the second carbon in the rubber composition was 16 parts by mass per 100 parts by mass of millable urethane polymer.

[0043] As shown in Table 1, the content of the organic peroxide crosslinking agent in the rubber composition was 2.8 parts by mass per 100 parts by mass of millable urethane polymer in Examples 1 to 5. In Example 6, the content of the organic peroxide crosslinking agent in the rubber composition was 4.2 parts by mass per 100 parts by mass of millable urethane polymer.

[0044] In Examples 1 to 6, additives such as plasticizers, anti-hydrolysis agents, antioxidants, chemical dispersants, lubricants, and accelerators were added as appropriate.

[0045] [Example 1] In Example 1, 100 parts by mass of the polymer used was a millable urethane polymer manufactured by NOK Corporation under the trade name "Iron Rubber" and having a Mooney viscosity ML(1+4)100°C of 29.0.

[0046] [Example 2] In Example 2, 50 parts by mass of the polymer used was a millable urethane polymer manufactured by AQOS Corporation under the product name "E8010" and having a Mooney viscosity ML(1+4)100°C of 66.0, and 50 parts by mass of the polymer used was a millable urethane polymer manufactured by AQOS Corporation under the product name "E8010" and having a Mooney viscosity ML(1+4)100°C of 40.0.

[0047] [Example 3] In Example 3, a millable urethane polymer manufactured by Eikos Corporation under the trade name "E8010" and having a Mooney viscosity ML(1+4)100°C of 66.0 was used as 100 parts by mass of the polymer.

[0048] [Example 4] In Example 4, 50 parts by mass of the polymer used was a millable urethane polymer manufactured by AQOS Corporation under the product name "E8010" and having a Mooney viscosity ML(1+4)100°C of 66.0, and 50 parts by mass of the polymer used was a millable urethane polymer manufactured by AQOS Corporation under the product name "E8010" and having a Mooney viscosity ML(1+4)100°C of 90.0.

[0049] [Example 5] In Example 5, a millable urethane polymer manufactured by Eikos Corporation under the trade name "E8010" and having a Mooney viscosity ML(1+4)100°C of 90.0 was used as 100 parts by mass of the polymer.

[0050] [Example 6] In Example 6, as in Example 5, a millable urethane polymer manufactured by Eikos Corporation under the product name "E8010" and having a Mooney viscosity ML(1+4)100°C of 90.0 was used as 100 parts by mass of the polymer.

[0051] [Measurement of Mooney viscosity ML(1+4) at 100℃] The Mooney viscosity ML(1+4)100°C of the millable urethane polymers of Examples 1 to 6 was measured. The Mooney viscosity ML(1+4)100°C was measured under the following measurement conditions: test temperature 100°C, L-shaped rotor, preheating time 1 minute, rotor rotation time 4 minutes. The Mooney viscosity ML(1+4)100°C of Examples 1 to 6 is shown in Table 2 below.

[0052] [Table 2]

[0053] As shown in Table 2 above, the Mooney viscosity ML(1+4) at 100°C of Example 1 was 29.0. The Mooney viscosity ML(1+4) at 100°C of Example 2 was 53.0. The Mooney viscosity ML(1+4) at 100°C of Example 3 was 66.0. The Mooney viscosity ML(1+4) at 100°C of Example 4 was 78.0. The Mooney viscosity ML(1+4) at 100°C of Example 5 was 90.0. The Mooney viscosity ML(1+4) at 100°C of Example 6 was 90.0.

[0054] [Measurement of tensile modulus] The tensile modulus [MPa] of the rubbers obtained by crosslinking the rubber compositions of Examples 1 to 6 and the comparative example was measured. The comparative example was a commercially available blend of natural rubber (NR) and butadiene rubber (BR).

[0055] M100, M200, and M300 were measured for Examples 1 to 6 and the Comparative Example. M100 is the tensile force [MPa] when the test piece is pulled until it has elongated to 100%. M200 is the tensile force [MPa] when the test piece is pulled until it has elongated to 200%. M300 is the tensile force [MPa] when the test piece is pulled until it has elongated to 300%. The tensile force was measured using a Tensilon Universal Material Testing Machine (product number: RT1-1310) manufactured by A&D Co., Ltd.

[0056] The tensile moduli [MPa] of Examples 1 to 6 and the comparative example are shown in Table 2. Fig. 1 is a graph showing the measurement results of the tensile moduli [MPa] of Examples 1 to 6 and the comparative example. In Fig. 1, a black square represents Example 1, a white triangle represents Example 2, a white circle represents Example 3, a white square represents Example 4, a black triangle represents Example 5, a black circle represents Example 6, and a white diamond represents the comparative example.

[0057] As shown in Table 2 and Figure 1, the tensile modulus of M100 in Example 1 was 2.3 [MPa], the tensile modulus of M200 in Example 1 was 6.5 [MPa], and the tensile modulus of M300 in Example 1 was 12.7 [MPa].

[0058] The tensile modulus of M100 in Example 2 was 2.7 [MPa]. The tensile modulus of M200 in Example 2 was 8.0 [MPa]. The tensile modulus of M300 in Example 2 was 14.7 [MPa].

[0059] The tensile modulus of M100 in Example 3 was 2.9 [MPa]. The tensile modulus of M200 in Example 3 was 8.8 [MPa]. The tensile modulus of M300 in Example 3 was 16.2 [MPa].

[0060] The tensile modulus of M100 in Example 4 was 3.2 [MPa]. The tensile modulus of M200 in Example 4 was 9.7 [MPa]. The tensile modulus of M300 in Example 4 was 17.9 [MPa].

[0061] The tensile modulus of M100 in Example 5 was 3.0 [MPa], the tensile modulus of M200 in Example 5 was 9.4 [MPa], and the tensile modulus of M300 in Example 5 was 17.7 [MPa].

[0062] From the results of Examples 1 to 4 above, it was confirmed that by increasing the Mooney viscosity ML(1+4)100°C, the tensile modulus of M100, M200, and M300 can be improved without increasing the content of carbon as a reinforcing material.

[0063] On the other hand, in Example 5, although the Mooney viscosity ML(1+4)100°C was high at 90, it was confirmed that the tensile moduli M100, M200, and M300 were lower than those of Example 4. However, in Example 6, although the Mooney viscosity ML(1+4)100°C was 90, which was the same as that of Example 5, it was confirmed that the tensile moduli M100, M200, and M300 were improved compared to Example 5. It was also confirmed that the tensile moduli M100, M200, and M300 were improved in Example 6 compared to Example 4.

[0064] The only difference between Examples 5 and 6 was the amount of organic peroxide crosslinking agent. Long molecular chain polymers have a greater number of crosslinking points than short molecular chain polymers. Therefore, a long molecular chain polymer with a high Mooney viscosity ML(1+4)100°C of 90 requires an amount of organic peroxide crosslinking agent commensurate with the number of crosslinking points. Therefore, from the difference in tensile modulus between Examples 5 and 6, it was confirmed that when the Mooney viscosity ML(1+4)100°C is 90, the tensile modulus of M100, M200, and M300 can be improved by increasing the content of organic peroxide crosslinking agent.

[0065] On the other hand, it was confirmed that the tensile moduli M100, M200, and M300 of the comparative example were lower than those of any of the examples 1 to 6.

[0066] From the above results, it was confirmed that Examples 1 to 6 had higher tensile moduli M100, M200, and M300 than the comparative example.

[0067] [Hardness measurement] The Shore A hardness (HA) of the rubbers obtained by crosslinking the rubber compositions of Examples 1 to 6 and the Comparative Example was measured. The hardness (HA) was measured using a rubber / plastic hardness meter (product number: GS-701N) manufactured by Teclock Corporation.

[0068] The hardness (HA) of Examples 1 to 6 and the comparative example is shown in Table 2 above.

[0069] As shown in Table 2 above, the hardness (HA) of Example 1 was 61.0. The hardness (HA) of Example 2 was 64.0. The hardness (HA) of Example 3 was 66.0. The hardness (HA) of Example 4 was 68.0. The hardness (HA) of Example 5 was 67.0. The hardness (HA) of Example 6 was 67.0. The hardness (HA) of the comparative example was 65.0.

[0070] From the above results, it was confirmed that Examples 1 to 6 had high hardness (HA) comparable to that of the comparative example.

[0071] [Evaluation of ride comfort and handling stability] Four drivers drove vehicles equipped with the suspension bushings of Examples 2 to 4 and the Comparative Example, and evaluated the ride comfort and handling stability. The evaluations of ride comfort and handling stability are shown in Table 3 below.

[0072] [Table 3]

[0073] In Table 3 above, steering responsiveness indicates the responsiveness when the steering wheel is turned ±2° and ±30° when traveling at 40 km / h. Steering response indicates the responsiveness when the steering wheel is turned ±2° and ±30° when traveling at 100 km / h. Ride comfort and handling indicate the handling and ride comfort evaluations during normal driving (traveling at 60 km / h or less). Stability, security, and tracking indicate the vehicle's sense of stability and lack of delay when the steering wheel is turned ±30° while traveling around a curve at 120 km / h. Roll feeling and roll resonance indicate the roll feeling and roll convergence when the steering wheel is turned ±30° at 100 km / h. General ride comfort indicates the ride comfort when going over a small bump of about 5 to 10 mm and going over a manhole at 40 km / h.

[0074] In the items in Table 3 above, steering response, steering feel, handling, stability, sense of security, tracking ability, roll feeling, and handling stability indicated by roll resonance, Example 3 received the highest rating, followed by Example 2, Example 4, and the comparative example received the lowest rating.

[0075] In addition, in terms of the vehicle ride comfort shown in the items of ride comfort and general ride comfort in Table 3 above, Example 3 received the highest rating, followed by Example 2, Example 4, and the comparative example received the lowest rating.

[0076] From the above results, it was confirmed that Examples 2 to 4 had higher handling stability and ride comfort than the comparative example. It was also confirmed that handling stability and ride comfort improved in the order of Example 4, Example 2, and Example 3.

[0077] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

Claims

1. Millable urethane polymer, an organic peroxide crosslinking agent; Nitrogen surface area is 30m ２ / g or more 100m ２ / g or less of carbon; Equipped with The millable urethane polymer has a Mooney viscosity ML(1+4)100°C of 29 or more and 90 or less, The content of the organic peroxide crosslinking agent is 2 parts by mass or more and 4 parts by mass or less relative to 100 parts by mass of the millable urethane polymer, The rubber composition has a carbon content of 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the millable urethane polymer.

2. The rubber composition according to claim 1, wherein the millable urethane polymer has a Mooney viscosity ML(1+4) 100°C of 53 or more and 78 or less.

3. The rubber composition according to claim 1 or 2, wherein the carbon comprises a first carbon and a second carbon having a nitrogen surface area different from that of the first carbon.

4. The nitrogen surface area of ​​the first carbon is 30 m ２ / g or more 50m ２ / g, The nitrogen surface area of ​​the second carbon is 70 m ２ / g or more 90m ２ The rubber composition according to claim 3, wherein the modulus is 1 / g.

5. Millable urethane polymer, an organic peroxide crosslinking agent; Nitrogen surface area is 30m ２ / g or more 100m ２ / g or less of carbon; Equipped with The millable urethane polymer has a Mooney viscosity ML(1+4)100°C of 29 or more and 90 or less, The content of the organic peroxide crosslinking agent is 2 parts by mass or more and 4 parts by mass or less relative to 100 parts by mass of the millable urethane polymer, A vibration-proof rubber comprising a rubber obtained by crosslinking a rubber composition in which the carbon content is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the millable urethane polymer.

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