JP4701790B2 - Method for producing anti-vibration rubber composition - Google Patents

Description

The present invention relates to a method for producing a vibration-proof rubber composition using a special carbon black, and more specifically, a vibration-proof rubber used for molding materials such as tires for automobiles and vibration suppressing rubber materials such as vibration-proof rubbers. The present invention relates to a method for producing a composition.

Conventionally, as an anti-vibration rubber material for an automobile tire or the like, a rubber material such as natural rubber blended with various additives such as carbon black and sulfur has been used. By using carbon black having a small particle size as the carbon black used in such an anti-vibration rubber material, the amplitude dependency of the static spring constant can be increased, and for example, the steering stability of the vehicle can be improved. . However, when carbon black having such a small particle size is used, the dynamic magnification is increased, and there is a problem that the riding comfort of the vehicle is deteriorated. In order to solve this problem, a rubber composition is proposed in which 8 to 30 parts by weight of zinc oxide and carbon black having an average particle diameter of 40 nm or less (preferably, an average particle diameter of 30 nm or less) are blended with 100 parts by weight of rubber. (For example, refer to Patent Document 1).
JP 2002-97307 A

  However, in the above-mentioned Patent Document 1, since carbon black having a small particle size with an average particle size of 30 nm or less is used, as described above, there is a sufficient problem that the dynamic magnification is increased and the riding comfort of the vehicle is deteriorated. However, there is a need for a significant improvement in dynamic characteristics by reducing the dynamic magnification.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for producing a vibration-proof rubber composition having improved vibration characteristics by reducing dynamic magnification and having excellent vibration suppression performance.

In order to achieve the above object, the method for producing a vibration-insulating rubber composition of the present invention includes the raw material carbon black together with metal spheres, and the mixing ratio of carbon black and metal spheres in a volume ratio of carbon black: metal sphere = 1. : Carbon black provided with the following characteristics (b1) and (b2) by charging into a pulverizer so as to be 2 to 1: 4 and performing a pulverization treatment at a centrifugal acceleration of 80 to 160 G for 2 to 15 minutes [(B) In addition to the step of preparing the component] and the carbon black (component (B)) having the above characteristics, the blending component containing the following component (A) and component (C) is added to the blending amount of the component (B). 20 to 100 parts by weight with respect to 100 parts by weight of component (A), and the blending amount of component (C) is 0.3 to 10 parts by weight with respect to 100 parts by weight of component (A). To mix and knead Ri, pressure pulse method NMR analysis after curing (NMR) SOLID relaxation time measured by ECHO method (T2L) takes a structure that includes a step of producing a vibration damping rubber composition is less than 350Myuesu.
(A) Diene rubber.
(B) Carbon black having the following characteristics (b1) and (b2).
(B1) The nitrogen adsorption specific surface area (N ₂ SA) is 150 m ² / g ≦ N ₂ SA ≦ 195 m ² / g.
(B2) DBP oil absorption amount (DBP) ^{is, 50cm 3 / 100g ≦ DBP ≦} 80cm 3 / 100g.
(C) Vulcanizing agent.

  In order to obtain an anti-vibration rubber capable of exhibiting excellent dynamic characteristics due to a reduction in dynamic magnification, the present inventor has earnestly studied the compounding components of the anti-vibration rubber composition as the molding material and the physical properties of the anti-vibration rubber itself. Repeated. And as a result of continuing research centering on carbon black, which is one component of the vibration-insulating rubber composition, focusing on the nitrogen adsorption specific surface area and DBP oil absorption of carbon black, and continuing research on the appropriate range of these characteristics, We found out that good results can be obtained by setting a specific range. That is, when carbon black that has been treated to fall within the specific range is used, the rubber component around the carbon black clings to the carbon black and the rubber component is constrained. Then, by defining the relaxation time (T2L) measured by the pulsed nuclear magnetic resonance analysis (NMR) SOLID ECHO method after vulcanization, which is an index indicating it, a reduction in dynamic magnification can be achieved. As a result, the inventors have found that excellent dynamic characteristics are exhibited and the intended purpose is achieved, and the present invention has been achieved.

  More specifically, since it is already known that information on molecular motion can be obtained by the relaxation time measured by the pulsed nuclear magnetic resonance analysis (NMR) SOLID ECHO method, the present inventor We estimated that the vibration characteristics of the diene rubber component in the vicinity of the carbon black to be blended might affect the vibration characteristics, and examined the relevance by paying attention to the effect of the relaxation time on the dynamic magnification. As a result, when the relaxation time is set to a specific time or less, it has been found that the dynamic magnification can be reduced, and by using the special carbon black that makes it possible to realize such relaxation time, excellent vibrations can be achieved. The inventors have found that suppression performance can be obtained and have reached the present invention.

The anti-vibration rubber composition obtained by the production method of the anti-vibration rubber composition of the present invention comprises a special carbon black (B) in which the nitrogen adsorption specific surface area (b1) and the DBP oil absorption (b2) are set in specific ranges, respectively. While being used, the relaxation time (T2L) measured by the pulsed NMR SOLID ECHO method after vulcanization of the vibration-proof rubber composition containing this special carbon black is set to a specific value or less. For this reason, the dynamic magnification is reduced, and a vibration-proof rubber having excellent vibration suppression performance can be obtained.

  And if the mixture ratio of the said carbon black (B) is set to a specific range, it will be excellent in a physical property and the sufficient reduction effect of dynamic magnification will be acquired.

  Next, an embodiment of the present invention will be described.

The anti-vibration rubber composition according to the present invention can be obtained using a diene rubber (A), special carbon black (B), and a vulcanizing agent (C). In the present invention, the relaxation time (T2L) measured by the pulse method NMR SOLID ECHO method after vulcanization of the vibration-proof rubber composition is set within a specific range, and the special carbon black (B ) And setting the relaxation time (T2L) is the greatest feature of the present invention.

  The diene rubber (A) is not particularly limited, and examples thereof include isoprene rubbers such as natural rubber (NR) and isoprene rubber (IR), ethylene-propylene-diene terpolymers, and butadiene rubber (BR). And styrene-butadiene rubber (SBR). These may be used alone or in combination of two or more.

  Next, the carbon black (B) used together with the diene rubber (A) is not particularly limited as long as it has the following characteristics (b1) and (b2). Thus, if carbon black (B) having a special relationship with a high nitrogen adsorption specific surface area (b1) and a small DBP oil absorption (b2) can be produced by processing, for example, SAF class, ISAF class, Any of various types of carbon black such as HAF class, MAF class, FEF class, GPF class, SRF class, FT class, MT class, etc. may be used. These may be used alone or in combination of two or more.

(B1) The nitrogen adsorption specific surface area (N ₂ SA) is 150 m ² / g ≦ N ₂ SA ≦ 195 m ² / g.
(B2) DBP oil absorption amount (DBP) ^{is, 50 cm 3 / 100g ≦ DBP} ≦ 80 cm 3 / 100g.

That is, when the nitrogen adsorption specific surface area (N ₂ SA) is less than 0.99 m ² / g, is insufficient contact area between the rubber component and carbon black, a reinforcing effect is not sufficient, on the contrary 195 This is because if it exceeds m ² / g, the viscosity of the unvulcanized rubber is high and the processability is lowered.

Further, when the DBP oil absorption (DBP) is less than 50 cm ^3/100 g, is insufficient reinforcing effect, when it exceeds 80 cm ^3/100 g Conversely, because the effect of reducing the dynamic magnification is reduced .

In the present invention, the nitrogen adsorption specific surface area (N ₂ SA) and the DBP oil absorption (DBP) can be measured according to JIS K6217.

  The special carbon black (B) having such specific characteristics can be produced, for example, as follows. That is, the carbon black as a raw material can be prepared by putting it into a pulverizer together with a metal sphere described later and performing a pulverization process at a predetermined centrifugal acceleration. An example of the pulverizer is a planetary mill, for example, a batch type high-speed planetary mill “Kurimoto Hygie” BX384E manufactured by Kurimoto Iron Works. Examples of the metal sphere include a stainless sphere. A diameter of about 1 to 4 mm is preferably used, and a diameter of 2 to 3 mm is particularly preferably used.

  The mixing ratio of the carbon black and the metal sphere is preferably set in a volume ratio of carbon black: metal sphere = 1: 2 to 1: 4. Moreover, it is preferable to set the charging ratio of the carbon black and the metal sphere to be 20 to 40% by volume of the total volume of the pulverizer. And as grinding | pulverization process conditions by the said grinder, it is preferable to set centrifugal acceleration to the range of 80-160G with respect to a metal ball, More preferably, it is 100-150G. Furthermore, it is preferable to set the pulverization time by the pulverizer to 2 to 15 minutes.

  By using the carbon black (B) treated as described above, the state of the rubber component (A) around the carbon black (B) is changed, and the rubber component (A) is bonded to the carbon black (B). As a result, the relaxation time (T2L) measured by the pulsed NMR SOLID ECHO method after vulcanization can be defined as 350 μs or less, and vibration suppression can be improved by reducing the dynamic magnification. .

The blending ratio of the special carbon black (B) is in the range of 20 to 100 parts, particularly preferably 30 to 70, with respect to 100 parts by weight (hereinafter abbreviated as “parts”) of the diene rubber (A). Within the range of the part. That is, if the special carbon black (B) is less than 20 parts, it is difficult to obtain a sufficient dynamic magnification reduction effect, and conversely if it exceeds 100 parts, the physical properties tend to decrease.

Sulfur is suitably used as the vulcanizing agent (C) used together with the components A to B. The amount of sulfur is in the range of 0.3 to 10 parts, particularly preferably in the range of 0.5 to 5 parts, with respect to 100 parts of the diene rubber (A).

The anti-vibration rubber composition according to the present invention includes a vulcanization accelerator, a vulcanization aid, an anti-aging agent, a processing aid, a softening agent and the like as needed in addition to the components A to C described above. It is also possible to mix.

  The vulcanization accelerator is not particularly limited. For example, thiazole accelerator, thiuram accelerator, N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide (MBTS), 2 -Sulfenamide accelerators such as mercaptobenzothiazole (MBT) and tetramethylthiuram monosulfide (TMTM).

  The blending amount of the vulcanization accelerator is preferably in the range of 0.1 to 3 parts, particularly preferably in the range of 0.5 to 2 parts, with respect to 100 parts of the diene rubber (A).

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

  The blending amount of the ZnO is preferably 5 parts or less with respect to 100 parts of the diene rubber (A). If it is in such a range, it will be in a normal range, and there will also be no problem of the weight increase of the product accompanying the increase in ZnO.

  Examples of the antiaging agent include carbamate type antiaging agents, phenylenediamine type antiaging agents, phenol type antiaging agents, diphenylamine type antiaging agents, quinoline type antiaging agents, and waxes.

  The amount of the antioxidant is preferably in the range of 1 to 7 parts, particularly preferably in the range of 2 to 5 parts, with respect to 100 parts of the diene rubber (A).

  Examples of the processing aid include stearic acid, fatty acid esters, fatty acid amides, hydrocarbon resins, and the like.

  The blending amount of this processing aid is preferably in the range of 1 to 5 parts, particularly preferably in the range of 1 to 3 parts, relative to 100 parts of the diene rubber (A).

The anti-vibration rubber composition according to the present invention includes, for example, an additive such as a vulcanization accelerator in the diene rubber (A), the specific carbon black (B) and the vulcanizing agent (C) as necessary. It can mix and knead | mix these using a roll, a Banbury mixer, etc., and can prepare.

The use of the vibration- insulating rubber composition according to the present invention thus obtained is not particularly limited, but is suitably used as a vibration-insulating rubber material in vehicles such as automobiles.

The anti-vibration rubber using the anti-vibration rubber composition according to the present invention is formed, for example, by press-vulcanizing the anti-vibration rubber composition prepared as described above under a predetermined condition to form a predetermined shape. Can be produced.

  Although it does not specifically limit as vulcanization conditions of the vibration-proof rubber composition in this invention, The inside of the range of 145-180 degreeC x 20-60 minutes is preferable, Most preferably, 150-160 degreeC x 30-45 minutes It is.

The rubber molded body after vulcanization of the vibration- insulating rubber composition according to the present invention thus obtained must have a relaxation time (T2L) measured by the pulsed NMR SOLID ECHO method of 350 μs or less. Particularly preferably, it is 300 μs or less. That is, when the relaxation time (T2L) exceeds 350 μs, the dynamic magnification reduction effect is reduced, and a desired vibration suppression performance cannot be obtained. The relaxation time (T2L) measured by the pulse method NMR SOLID ECHO method is measured as follows, for example. First, a rubber sheet is formed by heat vulcanization using the vibration-proof rubber composition, and the rubber sheet is cut into rubber chips having a predetermined size (for example, about 2 to 3 mm square). Using this rubber chip test piece, the pulse sequence is SOLID ECHO (solid echo) method at room temperature (25 ± 2 ° C.), and spin-spin relaxation is performed by a pulse NMR apparatus JNM-MU25 / BU manufactured by JEOL Ltd. Time (T2) is measured. Usually, when a vulcanized rubber compounded with carbon black is measured, the spin-spin relaxation time (T2) can be separated into two components, so the value with the longer relaxation time is defined as the relaxation time (T2L) of the present invention. .

Application of the vibration damping rubber composition according to the present invention thus obtained is not particularly limited, it is suitably used as vibration suppressing rubber material, such as tires and various vibration damping rubber member, such as an automobile.
The

  Next, examples will be described together with comparative examples.

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

[Carbon black a]
Carbon black a having the characteristics shown in Table 1 below was produced. That is, 90 g of HAF grade carbon black (Showa Cabot, Show Black N330) and 3.2 kg of stainless steel balls with a diameter of 2 mm so that it accounts for 40% of the total input volume of the planetary mill (the mixing volume ratio of both is carbon black: stainless steel) Sphere = 1: 3) is put into a planetary mill (batch type high-speed planetary mill “Kurimoto Hygie” BX384E manufactured by Kurimoto Iron Works Co., Ltd.), and a stainless steel ball is crushed at a centrifugal acceleration of 150 G × 15 minutes. Thus, carbon black a was produced. Each characteristic of the obtained carbon black a was measured according to JIS K6217 and based on the method described above, and is shown in Table 1 below. Further, the average Stokes diameter (Dst) is the maximum weight fraction in the weight distribution curve of the Stokes diameter of the carbon black aggregate measured by the disc centrifuging (DCF) method described in JP-A-2001-40239. The Stokes equivalent diameter is shown.

[Carbon black b]
The grinding time by the planetary mill was 30 minutes. Otherwise, carbon black b was produced in the same manner as carbon black a. Each characteristic of the obtained carbon black b was measured in the same manner as the carbon black a and is shown in Table 1 below.

[Carbon black c]
Along with HAF grade carbon black (Showa Cabot, Show Black N330) and 2 mm diameter stainless steel sphere, 9 g of phenolic compound (Ouchi Shinsei Chemical Co., Ltd., Nocrack 200) as an anti-aging agent was added simultaneously. Otherwise, carbon black c was prepared in the same manner as carbon black a. Each characteristic of the obtained carbon black c was measured in the same manner as the carbon black a and is shown in Table 1 below.

[Carbon black d]
HAF grade carbon black (Showa Cabot Co., Show Black N330) was used as it was. The properties of this HAF grade carbon black were measured in the same manner as the carbon black a and are shown in Table 1 below.

[NR]
Natural rubber

[Vulcanization aid]
Zinc oxide (ZnO) [Mitsui Metals Mining Co., Ltd., zinc oxide type 2]

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

〔sulfur〕
Sulfax200S manufactured by Tsurumi Chemical Co., Ltd.

[Vulcanization accelerator (CBS)]
Nouchira CZ-G, manufactured by Ouchi Shinsei Chemical Co., Ltd.

[Examples 1-5, Comparative Examples 1-2]
The components shown in Table 2 below were blended in the proportions shown in the same table, and these were kneaded using a Banbury mixer to prepare an anti-vibration rubber composition.

  Using the anti-vibration rubber compositions of Examples and Comparative Examples thus obtained, each characteristic was evaluated according to the following criteria. These results are also shown in Table 2 below.

[Normal physical properties]
Each rubber composition was press-molded under conditions of 150 ° C. × 20 minutes and punched with a JIS No. 5 dumbbell to prepare a vulcanized rubber sheet having a thickness of 2 mm. Then, using this anti-vibration rubber sheet, the breaking strength (TB), breaking elongation (EB), and hardness (JIS A) were measured in accordance with JIS K6251.

[Dynamic magnification]
Each rubber composition was vulcanized at 150 ° C. for 20 minutes to prepare a vulcanized rubber sheet having a thickness of 2 mm. A strip-shaped test piece having a width of 5 mm × a length of 50 mm was cut out from this sheet, and the room temperature ( At 25 ° C.) using a Rheogel-E4000 made by UBM, storage modulus (E′100 Hz) at a frequency of 100 Hz and a strain of 0.05%, and storage modulus at a frequency of 15 Hz and a strain of 4.5% (E ′) was measured and indicated as E′100 Hz / E ′ = dynamic magnification.

[Relaxation time]
Using the anti-vibration rubber compositions of the example product and the comparative product, press molding was performed at 150 ° C. for 20 minutes to produce a vulcanized rubber sheet having a thickness of 2 mm, and further cut into 2 to 3 mm squares to form rubber chips. Produced. Using this rubber chip test piece, at 27 ° C., the pulse sequence uses the solid echo (SOLID ECHO) method, and the spin-spin relaxation time (T2) is measured by a pulse NMR apparatus JNM-MU25 / BU manufactured by JEOL Ltd. Measurement was made and the relaxation time of the shorter value (T2s) and the relaxation time of the longer value (T2L) were shown together with the amount of each component.

  From the above results, it is apparent that all the products of the examples have the normal state physical properties equivalent to those of the prior art, and the dynamic magnification has been reduced.

  On the other hand, it can be seen that all of the comparative example products have high dynamic magnification and inferior vibration suppression performance.

The anti-vibration rubber composition according to the present invention is used as a molding material for vibration-suppressing rubber materials such as automobile tires and various anti-vibration rubber members.

Claims (2)

The raw material carbon black together with the metal spheres was introduced into the pulverizer so that the mixing ratio of the carbon black and the metal spheres by volume ratio was carbon black: metal sphere = 1: 2 to 1: 4, and the centrifugal acceleration was 80 to 160G. And a step of producing a carbon black (component (B)) having the following characteristics (b1) and (b2) by pulverizing for 2 to 15 minutes, and carbon black (component (B) having the above characteristics: In addition, the blending component containing the following component (A) and component (C), the blending amount of the component (B) is 20 to 100 parts by weight with respect to 100 parts by weight of the component (A), and the above (C) Compounding amount of component is 0.3 to 10 parts by weight with respect to 100 parts by weight of component (A), and kneaded to obtain a pulsed nuclear magnetic resonance analysis (NMR) after vulcanization. ) SOLID E And a process for producing an anti-vibration rubber composition having a relaxation time (T2L) measured by the CHO method of 350 μs or less .
(A) Diene rubber.
(B) Carbon black having the following characteristics (b1) and (b2).
(B1) The nitrogen adsorption specific surface area (N ₂ SA) is 150 m ² / g ≦ N ₂ SA ≦ 195 m ² / g.
(B2) DBP oil absorption amount (DBP) ^{is, 50cm 3 / 100g ≦ DBP ≦} 80cm 3 / 100g.
(C) Vulcanizing agent.   The method for producing an anti-vibration rubber composition according to claim 1, wherein the charging ratio of the carbon black and the metal sphere to the pulverizer is 20 to 40% by volume of the total volume of the pulverizer.