JP6456780B2 - Anti-vibration rubber manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a vibration-proof rubber.

  Anti-vibration rubber is used for vehicles such as automobiles in order to absorb vibrations of the engine and the vehicle body and improve riding comfort and prevent noise. Such an anti-vibration rubber is required to reduce the dynamic magnification (dynamic spring constant / static spring constant) in order to enhance the vibration absorption effect.

  In Patent Document 1, a thiosulfuric acid compound such as S- (3-aminopropyl) thiosulfuric acid or a salt thereof is kneaded together with a rubber component and a filler (carbon black), and sulfur and vulcanization are accelerated in the obtained kneaded product. It is disclosed that kneading the agent reduces the dynamic ratio of the vulcanized rubber. Although the dynamic magnification can be reduced by using the thiosulfate compound as described above, it has been found that the conventional kneading method decreases the scorch resistance.

  Incidentally, blending the thiosulfuric acid compound as described above into the rubber composition is also disclosed in Patent Documents 2 to 4. For example, Patent Document 2 discloses a method for producing a vulcanized rubber in which a thiosulfuric acid compound, a rubber component, a filler, and a sulfur component are kneaded, and the resulting mixture is heat-treated. Carbon black and a thiosulfuric acid compound are kneaded with rubber, and sulfur is added to the obtained kneaded product and kneaded. In Patent Document 3, after pre-kneading a thiosulfuric acid compound with a diene rubber, a filler such as carbon black is kneaded with the obtained kneaded material, and then a vulcanizing compounding agent is mixed. Is disclosed. Patent Document 4 discloses that a diene rubber is kneaded with a filler containing silica and a silane coupling agent, and then kneaded with a thiosulfuric acid compound in the obtained kneaded product. However, these are merely disclosures of improving viscoelastic properties that contribute to low fuel consumption primarily in tire applications.

  As described above, Patent Document 4 discloses that in a rubber composition for tires, a diene rubber is kneaded with a filler in advance, and then a thiosulfuric acid compound is kneaded. In order to prevent the reaction between silica and the silane coupling agent from being inhibited by the reaction of the thiosulfuric acid compound with silica or a silane coupling agent, it is disclosed that the thiosulfuric acid compound is kneaded in the next step It is. It is not disclosed that an excellent effect for use in vibration-proof rubber can be obtained by kneading a diene rubber and carbon black under predetermined conditions and then kneading a thiosulfuric acid compound into the obtained kneaded product.

JP 2013-049838 A JP 2011-202138 A JP 2014-177518 A JP 2014-218544 A

  An object of this invention is to provide the manufacturing method of the vibration-proof rubber which can reduce a dynamic magnification, suppressing the fall of scorch resistance.

In the method for producing a vibration-proof rubber according to the present invention, a diene rubber and carbon black are first kneaded for 20 seconds or more after the temperature of the kneaded material reaches 155 ° C. and until the temperature of the kneaded material reaches 165 ° C. or higher. A kneading step, and a second kneading step of kneading the obtained kneaded product and the thiosulfuric acid compound represented by the following formula (1) and / or a salt thereof at an upper limit of kneading temperature of 70 to 120 ° C.

（式（１）において、ｎは０〜１０の整数を示す。）

(In formula (1), n represents an integer of 0 to 10.)

  According to the present invention, the dynamic magnification can be reduced while suppressing a decrease in scorch resistance.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The method for producing a vibration-proof rubber according to the present embodiment includes kneading a diene rubber and carbon black for 20 seconds or more after the temperature of the kneaded product reaches 155 ° C. and until the temperature of the kneaded product reaches 165 ° C. or higher. 1 kneading | mixing process and the 2nd kneading | mixing process of kneading | mixing the obtained kneaded material and the thiosulfuric acid compound represented by Formula (1) and / or its salt. Since the thiosulfuric acid compound or a salt thereof improves the dispersibility of carbon black in the diene rubber by reacting with carbon black, it is sufficiently mixed with the diene rubber and carbon black. Therefore, it is considered that the effect is exhibited more effectively. On the other hand, the present inventors surprisingly exerted the excellent dynamic magnification reduction effect by kneading the thiosulfuric acid compound or a salt thereof after sufficiently kneading carbon black with the diene rubber in advance. The present inventors have found that the scorch resistance can be improved. That is, according to the present embodiment, after kneading the diene rubber and carbon black under predetermined conditions, kneading the thiosulfuric acid compound or a salt thereof into the obtained kneaded product without deteriorating the scorch resistance, The dynamic magnification can be reduced.

  In this embodiment, examples of the diene rubber used as the rubber component include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), and acrylonitrile-butadiene rubber (NBR). Chloroprene rubber (CR), butyl rubber (IIR), etc. (modified rubbers each having a modified end or main chain may be used), and these may be used alone or in combination of two or more. it can. The diene rubber preferably contains NR and / or IR. The diene rubber may be composed only of NR and / or IR, and other diene rubber may be used in combination with NR and / or IR. Other diene rubbers are preferably BR and / or SBR, more preferably BR. In one embodiment, 100 parts by mass of the diene rubber may include 100 to 50 parts by mass of NR and / or IR and 0 to 50 parts by mass of BR, and 100 to 70 parts by mass of NR and / or IR. And 0 to 30 parts by mass of BR.

  Examples of the carbon black include SAF class (ASTM number N100 series), ISAF class (N200 series), HAF class (N300 series), FEF class (N500 series), GPF class (N600 series), SRF class (N700 series). ) Etc. are used. Among these, it is preferable to use at least one selected from the group consisting of HAF class, FEF class, and GPF class. The compounding amount of the carbon black is preferably 5 to 100 parts by mass, more preferably 20 to 80 parts by mass, and further preferably 30 to 70 parts by mass with respect to 100 parts by mass of the diene rubber.

  In the present embodiment, the filler may be carbon black alone, or other inorganic fillers such as silica may be used in combination with carbon black. The filler is preferably composed mainly of carbon black, and 50% by mass or more, more preferably 60% by mass or more of the amount of the filler is preferably carbon black.

  The rubber composition for vibration-proof rubber according to this embodiment is blended with the thiosulfuric acid compound represented by the above formula (1) and / or a salt thereof. As described above, not only a thiosulfate compound but also a salt thereof may be used, but it is preferable to use a thiosulfate compound that is not a salt because thiosulfate has deliquescence and poor storage properties. Here, examples of the salt include alkali metal salts such as lithium salt, sodium salt, potassium salt, and cesium salt; alkaline earth metal salts such as calcium salt and barium salt; transition metal salts such as cobalt salt and copper salt; zinc salt Typical metal salts such as: substituted or unsubstituted ammonium salts such as ammonium salts and trimethylammonium salts. Moreover, when using a thiosulfuric acid compound and its salt as a mixture thereof, such a mixture is, for example, a method of mixing a thiosulfuric acid compound and its salt, or a method of metallizing a part of a thiosulfuric acid compound using a metal alkali. A product obtained by a method of neutralizing a part of a metal salt of a thiosulfuric acid compound using a protonic acid can be used.

  Examples of the thiosulfuric acid compound represented by the above formula (1) include S- (2-aminoethyl) thiosulfuric acid, S- (3-aminopropyl) thiosulfuric acid, S- (4-aminobutyl) thiosulfuric acid, S- (5-aminopentyl) thiosulfuric acid, S- (6-aminohexyl) thiosulfuric acid, S- (7-aminoheptyl) thiosulfuric acid, S- (8-aminooctyl) thiosulfuric acid, S- (9-aminononyl) ) Thiosulfuric acid, S- (10-aminodecyl) thiosulfuric acid, S- (11-aminoundecyl) thiosulfuric acid, S- (12-aminododecyl) thiosulfuric acid, and n in formula (1) is 0 to It is preferably an integer of 4, more preferably n is an integer of 1 to 3, and still more preferably S- (3-aminopropyl) thiosulfuric acid where n is 1.

  The thiosulfate compound can be produced by any known method such as the method described in JP2013-49838A. For example, a monohaloalkylamine hydrochloride and a metal salt or ammonium salt of thiosulfate are used. It can be made to react. A salt of a thiosulfuric acid compound may be produced by neutralizing with a protic acid such as hydrochloric acid or sulfuric acid. Examples of the salt of the thiosulfuric acid compound include a method of reacting a monohaloalkylamine with a metal salt or ammonium salt of thiosulfuric acid, a reaction of a phthalimide potassium salt with a dihaloalkane, and a metal salt of thiosulfuric acid or It can be produced by a method such as a method of reacting with an ammonium salt.

  The amount of the thiosulfuric acid compound and / or salt thereof is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the rubber component. Preferably it is 0.2-2 mass parts.

  According to the manufacturing method according to the present embodiment, first, in the first kneading step, carbon black is added to the diene rubber and mixed, that is, kneaded. The amount of each component is as described above. The first kneading step is an operation generally referred to as non-pro kneading. Therefore, kneading is performed without adding sulfur and a vulcanization accelerator. In the present embodiment, as described above, in the first kneading step, kneading is performed without adding the thiosulfuric acid compound represented by the formula (1) and / or a salt thereof.

  The first kneading step can be performed using a Banbury mixer, a kneader, a roll or other kneader, and is preferably performed using a closed kneader such as a Banbury mixer.

  In the present embodiment, as described above, the kneading conditions in the first kneading step are (i) kneading for 20 seconds or more after the temperature of the kneaded product reaches 155 ° C., and (ii) the temperature of the kneaded product is 165. It is kneading until it becomes more than ° C.

  The above (i) is a kneading condition in which the kneading time (hereinafter referred to as kneading time A) from the time when the temperature of the kneaded product becomes 155 ° C. or higher until the temperature is discharged from the kneader is 20 seconds or more. Since the temperature of the kneaded product rises due to heat generated by shearing during kneading, after reaching 155 ° C., it is discharged from the kneader after 20 seconds or more. The kneading time A is preferably 30 seconds or more, and more preferably 40 seconds or more in order to enhance the dynamic magnification reduction effect. The upper limit of the kneading time A is not particularly limited, but is preferably 500 seconds or shorter, more preferably 200 seconds or shorter, and may be 100 seconds or shorter from the viewpoint of productivity.

  The above (ii) is a kneading condition in which the upper limit of the kneading temperature, that is, the temperature of the kneaded product when discharged from the kneader (hereinafter referred to as the first discharge temperature) is 165 ° C. or higher. As described above, the temperature of the kneaded product rises due to heat generated by shearing during kneading, so that after reaching 155 ° C., kneading is continued until it reaches 165 ° C. or higher. The first discharge temperature is preferably 170 ° C. or higher in order to enhance the dynamic magnification reduction effect. Although the upper limit of 1st discharge | emission temperature is not specifically limited, It is preferable that it is 220 degrees C or less, More preferably, it is 200 degrees C or less, and 180 degrees C or less may be sufficient.

  In the first kneading step, in addition to diene rubber and carbon black, other fillers such as silica, additives such as zinc white, stearic acid, wax, anti-aging agent and oil can be blended.

  As zinc white, various zinc whites (zinc oxide) generally used as a vulcanization accelerating aid in sulfur vulcanization of diene rubber can be used, and active zinc white having a large specific surface area can be used. Good. The compounding quantity of zinc white is not specifically limited, 0.5-15 mass parts with respect to 100 mass parts of diene rubbers, 1-10 mass parts may be sufficient, and 2-8 mass parts may be sufficient. By blending zinc white in the first kneading step, the dispersibility can be improved, and the coexistence effect of scorch resistance and dynamic magnification can be enhanced.

  According to the production method of the present embodiment, in the second kneading step, the thiosulfuric acid compound represented by formula (1) and / or a salt thereof is then added to the kneaded product obtained in the first kneading step. Knead. In the second kneading step, (a) the thiosulfuric acid compound and / or salt thereof may be added and kneaded with the vulcanizing agent and the vulcanization accelerator, or (b) the vulcanizing agent and the vulcanization acceleration. A thiosulfuric acid compound and / or a salt thereof may be added and kneaded without adding an agent.

  In the case of the above (a), in the second kneading step, the vulcanizing agent and the vulcanization accelerator are added and kneaded together with the thiosulfuric acid compound and / or salt thereof, so the second kneading step is a so-called professional kneading step. The pro-kneading step can be performed using, for example, a kneader such as an open roll or a Banbury mixer, and the upper limit of the kneading temperature, that is, the temperature of the kneaded material when discharged from the kneader (hereinafter referred to as pro-kneading discharge temperature). Is preferably at a lower temperature than the first kneading step from the viewpoint of scorch resistance, for example, preferably 70 to 120 ° C, more preferably 80 to 110 ° C.

  On the other hand, in the case of (b) above, in the second kneading step, thiosulfuric acid compound and / or salt thereof is added and kneaded, and then the obtained kneaded product is vulcanized in the final kneading step (pro kneading step) Add agent and vulcanization accelerator and knead. In this case, the second kneading step can be performed using, for example, a Banbury mixer, a kneader, a roll, or the like. In addition, the upper limit of the kneading temperature, that is, the temperature of the kneaded product when discharged from the kneader (hereinafter referred to as the second discharge temperature) can be set to a high temperature similar to the first discharge temperature of the first kneading step. However, in order to enhance the effect of improving the scorch resistance, it is preferably, for example, 70 to 120 ° C., more preferably 80 to 110 ° C., which is the same as that in the professional kneading step. In this case, in the second kneading step, other additives such as zinc white, stearic acid, wax, anti-aging agent, and oil may be blended. Moreover, the kneading conditions in the final kneading step after the second kneading step can be set in the same manner as in the professional kneading step.

  Examples of the vulcanizing agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur, and these can be used alone or in combination of two or more. The compounding quantity of a vulcanizing agent is not specifically limited, For example, 0.2-5 mass parts may be sufficient with respect to 100 mass parts of diene rubbers, and 0.5-3 mass parts may be sufficient.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators can be used alone or in combination of two or more. Among these, from the viewpoint of the effect of reducing the dynamic magnification, a sulfenamide vulcanization accelerator, or a combination of a sulfenamide vulcanization accelerator and a thiuram vulcanization accelerator is preferable. The compounding quantity of a vulcanization accelerator is not specifically limited, For example, 0.1-5 mass parts may be sufficient with respect to 100 mass parts of diene rubbers, and 0.2-3 mass parts may be sufficient.

  In the professional kneading step, a vulcanization retarder such as N-cyclohexylthiophthalimide and N-nitrosodiphenylamine, and a vulcanization accelerator such as zinc white may be blended together with these vulcanizing agent and vulcanization accelerator. The compounding quantity of a vulcanization retarder is not specifically limited, For example, 0.05-3 mass parts may be sufficient with respect to 100 mass parts of diene rubbers, and 0.1-1 mass part may be sufficient.

  According to the manufacturing method according to the present embodiment, a vibration-proof rubber is obtained by vulcanization molding using an unvulcanized rubber composition that is a kneaded product obtained by the above-mentioned professional kneading process. For example, the anti-vibration rubber according to the embodiment can be obtained by molding the unvulcanized rubber composition into a shape corresponding to the rubber member in the vibration isolator by injection molding or the like and performing vulcanization by heat treatment. Although it does not specifically limit as vulcanization temperature, It can be set as 120-200 degreeC, More preferably, it is 140-180 degreeC.

  Specific examples of the anti-vibration rubber according to this embodiment include engine mounts, strut mounts, body mounts, cab mounts, member mounts, differential mounts and other mounts, suspension bushings, arm bushings, torque bushing bushes, and torsional dampers. And various types of anti-vibration rubber for automobiles such as muffler hangers, damper pulleys, and dynamic dampers. In addition to automobiles, it can be suitably used for anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for construction, seismic isolation rubber bearings, etc., and seismic isolation rubber. Preferably, it is used for a vibration isolating rubber constituting a vibration isolating apparatus for an automobile.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Details of each component used in the examples and comparative examples are as follows.

・ NR: Natural rubber, RSS # 3
-BR: Butadiene rubber, "Buna CB22" manufactured by LANXESS
・ Carbon black HAF: “Seast 3” manufactured by Tokai Carbon
・ Carbon black GPF: “Seast V” manufactured by Tokai Carbon
・ Zinc flower: “Zinc flower No. 1” manufactured by Mitsui Mining & Mining
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Wax: “OZOACE2701” manufactured by Nippon Seisakusha
Anti-aging agent RD: “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Anti-aging agent 6C: “SANTOFLEX 6PPD” manufactured by Flexsys
Thiosulfuric acid compound: S- (3-aminopropyl) thiosulfuric acid. Synthesized by the method described in paragraph 0041 of JP2013-49838A-Sulfur: "Sulfur powder for rubber 150 mesh" manufactured by Hosoi Chemical Co., Ltd.
・ Vulcanization accelerator CZ: sulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, “Noxeller CZ-G (CZ)” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator TS: Thiuram-based, tetramethylthiuram monosulfide, “Suncellor TS” manufactured by Sanshin Chemical Industry Co., Ltd.
・ Vulcanization accelerator NS: sulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, “Suncellor NS-G” manufactured by Sanshin Chemical Industry Co., Ltd.
・ Vulcanization retarder CTP: N-cyclohexylthiophthalimide, “Anscorch CTP” manufactured by Kawaguchi Chemical Industry Co., Ltd.

  The evaluation method of the rubber composition is as follows.

[Scorch resistance]
A Mooney scorch test in accordance with JIS K6300 was performed using a rheometer (L-shaped rotor), and a t5 value (minute) at the time of measurement at a temperature of 125 ° C. for 1 minute was obtained. In Table 2, the values of Comparative Example 2-1 are shown in Table 2, and the values of Comparative Example 3-1 are shown in Table 3 as indices, each set to 100. The larger the index is, the larger the t5 value is. Therefore, it is difficult to scorch, and the scorch resistance is excellent (excellent workability).

[Static spring constant / dynamic magnification]
For a vulcanized rubber sample (50 mmΦ × 25 mm) obtained by vulcanizing each rubber composition at 150 ° C. × 25 minutes using a predetermined mold, the static spring constant Ks and the dynamic spring constant Kd are calculated as follows. And the ratio (Kd / Ks) was calculated to determine the dynamic magnification. About the static spring constant and the dynamic magnification, Table 1 shows the value of Comparative Example 1-1, Table 2 shows the value of Comparative Example 2-1, and Table 3 shows the value of Comparative Example 3-1 as an index of 100. . A smaller index indicates a smaller static spring constant. Also, the smaller the index, the lower the dynamic magnification and the better the dynamic characteristics.

  ・ Static spring constant (Ks): Tensilon manufactured by Orientec Co., Ltd. was used as a measuring machine, and vulcanized rubber samples were compressed between 0 and 5 mm (compression up to 20%) at a crosshead speed of 10 mm / min. Repeatedly, a second load-deflection diagram was drawn and calculated based on the following equation.

Static spring constant (N / mm) = (w2-w1) / (δ2-δ1)
In the formula, w1 is a load (N) when the deflection amount δ1 is 1.3 mm, and w2 is a load (N) when the deflection amount δ2 is 3.8 mm.

  -Dynamic spring constant (Kd): Using a dynamic servo manufactured by Kashiwamiya Seisakusho Co., Ltd. as a measuring machine, performing initial strain (compression) 10%, frequency 100 Hz, amplitude ± 0.05 mm (± 0.2%), JIS K6394 (The unit is N / mm).

[First embodiment]
A rubber composition for vibration-proof rubber was prepared according to the composition (parts by mass) and kneading conditions shown in Table 1 below using a 1.7 L hermetic Banbury mixer (manufactured by Kobe Steel). In each rubber composition, the blending amount of carbon black was adjusted so that the static spring constant was substantially constant.

  In detail, in Example 1-1, first, in Step I, NR and BR were introduced into a Banbury mixer, and then carbon black, zinc white, stearic acid, wax and an antioxidant were added and kneaded, When 58 seconds had elapsed after the temperature of the kneaded product reached 155 ° C., the kneaded product was discharged from the Banbury mixer (first discharge temperature = 170 ° C.). Thereafter, in Step III, the kneaded product obtained above is put into a Banbury mixer, sulfur, a vulcanization accelerator, a vulcanization retarder and a thiosulfate compound are added, and discharged at the time of kneading for 60 seconds, A rubber composition was obtained.

  Example 1-2 is an example in which the blending amount of the thiosulfate compound added in Step III is changed with respect to Example 1-1. Examples 1-3 and 1-4 are examples in which the kneading conditions in step I were changed as shown in Table 1 with respect to Example 1-1. In Example 1-5, a thiosulfuric acid compound is not added in Step III, but in Step II, and then sulfur, a vulcanization accelerator, and a vulcanization retarder are kneaded with Example 1-1. This is an example of performing Step III. In Step II, the kneaded product was discharged from the Banbury mixer when the kneading was performed for 60 seconds (second discharge temperature = 110 ° C.).

  Comparative Example 1-1 is an example in which the thiosulfuric acid compound was not added to Example 1-1, and the kneading conditions in Step I were changed as shown in Table 1. Comparative Example 1-2 is an example in which a thiosulfuric acid compound is kneaded in Step I. Comparative Examples 1-3 and 1-4 are examples in which the kneading conditions in Step I were changed with respect to Example 1-1.

  In all of Examples and Comparative Examples, the kneading time was set to 60 seconds in Step III, and the professional kneading discharge temperature was in the range of 100 to 110 ° C. Moreover, the 1st discharge temperature in the kneading | mixing conditions of the process I was adjusted by changing the setting of the kneading | mixing time A, and the rotation speed of the stirring rotor of a Banbury mixer.

  About each obtained rubber composition, scorch resistance, a static spring constant, and a dynamic magnification were measured and evaluated, respectively.

  The results are as shown in Table 1. In Comparative Example 1-2 in which a thiosulfuric acid compound was kneaded in Step I with respect to Comparative Example 1-1 as a control, the effect of reducing the dynamic magnification was obtained, but the scorch resistance Sexually deteriorated. In Comparative Examples 1-3 and 1-4, the deterioration of scorch resistance was suppressed by adding the thiosulfuric acid compound in Step III. However, since kneading in Step I was insufficient, the dynamic magnification was reduced. It was inferior in effect. On the other hand, after kneading the diene rubber and carbon black sufficiently in Step I, the Examples 1-1 to 1-5, in which the thiosulfuric acid compound was added in Step II or Step III, deteriorated scorch resistance. An excellent dynamic magnification reduction effect was obtained while suppressing the above.

[Second Embodiment]
According to the composition (parts by mass) and kneading conditions shown in Table 2 below, rubber compositions for vibration-proof rubber were prepared in the same manner as in the first example. For each rubber composition, scorch resistance, static spring constant and dynamic magnification were prepared. Was measured and evaluated. In addition, as conditions not described in Table 2, the pro-kneading discharge temperature in the step III was set in the range of 100 to 110 ° C. by setting the kneading time to 60 seconds as in the first example.

  The results are as shown in Table 2. In Comparative Example 2-4 in which a thiosulfuric acid compound was kneaded in Step I with respect to Comparative Example 2-1 as a control, the effect of reducing the dynamic magnification was obtained, but the scorch resistance Sexually deteriorated. In Comparative Example 2-2, the deterioration of scorch resistance was suppressed by adding the thiosulfuric acid compound in Step III, but since the kneading in Step I was insufficient, the effect of reducing the dynamic magnification was inferior. It was. In Comparative Example 2-3, kneading was sufficiently performed in Step I, but since no thiosulfuric acid compound was added in Step III, the dynamic magnification reduction effect was hardly obtained. On the other hand, after sufficiently kneading the diene rubber and carbon black in Step I, and Examples 2-1 to 2-3 in which the thiosulfuric acid compound was added in Step III, while suppressing the deterioration of scorch resistance Excellent dynamic magnification reduction effect was obtained.

[Third embodiment]
According to the composition (parts by mass) and kneading conditions shown in Table 3 below, rubber compositions for vibration-proof rubber were prepared in the same manner as in the first example, and for each rubber composition, scorch resistance, static spring constant and dynamic magnification were prepared. Was measured and evaluated. In addition, as conditions not described in Table 3, the pro-kneading discharge temperature in the step III was set in the range of 100 to 110 ° C. by setting the kneading time to 60 seconds as in the first example.

  The results are as shown in Table 3, and in Comparative Example 3-2 in which a thiosulfuric acid compound was kneaded in Step I with respect to Comparative Example 3-1, which was a control, the effect of reducing the dynamic magnification was obtained, but the scorch resistance Sexually deteriorated. In Comparative Example 3-3, the deterioration of scorch resistance was suppressed by adding the thiosulfuric acid compound in Step III, but because the kneading in Step I was insufficient, the effect of reducing the dynamic magnification was inferior. It was. On the other hand, when it was Examples 3-1 and 3-2, the outstanding dynamic-magnification reduction effect was acquired, suppressing the deterioration of scorch resistance.

Claims (3)

A first kneading step of kneading the diene rubber and carbon black for 20 seconds or more after the temperature of the kneaded product reaches 155 ° C. and until the temperature of the kneaded product reaches 165 ° C. or higher;
A second kneading step of kneading the obtained kneaded product and the thiosulfuric acid compound represented by the following formula (1) and / or a salt thereof at an upper limit of kneading temperature of 70 to 120 ° C . ;
A method for producing vibration-proof rubber including

(In formula (1), n represents an integer of 0 to 10.)   The method for producing an anti-vibration rubber according to claim 1, wherein in the second kneading step, a vulcanizing agent and a vulcanization accelerator are kneaded together with the kneaded product and the thiosulfuric acid compound and / or a salt thereof.   The compounding amount of the carbon black is 5 to 100 parts by mass with respect to 100 parts by mass of the diene rubber, and the compounding amount of the thiosulfuric acid compound and / or a salt thereof is 0.000 with respect to 100 parts by mass of the diene rubber. The manufacturing method of the vibration-proof rubber of Claim 1 or 2 which is 05-5 mass parts.