JP6107252B2 - Method for producing rubber composition for tire - Google Patents

Description

The present invention, low rolling resistance, a method of manufacturing a tire rubber composition so as to improve the steering stability and wear resistance.

  In recent years, as a required performance for pneumatic tires, it has been demanded that fuel efficiency performance is excellent with increasing interest in global environmental problems. In order to improve fuel efficiency, it is necessary to reduce rolling resistance. For this reason, by suppressing the heat generation of the rubber composition constituting the pneumatic tire, rolling resistance when the tire is made is reduced. Generally, 60 ° C. tan δ by dynamic viscoelasticity measurement is used as an index of exothermic property of the rubber composition. The smaller the tan δ (60 ° C.) of the rubber composition, the smaller the exothermic property.

  As a method for reducing the tan δ (60 ° C.) of the rubber composition, for example, the amount of carbon black is decreased or the particle size of the carbon black is increased. However, such a method has a problem that mechanical properties such as tensile breaking strength, tensile breaking elongation, and rubber hardness are lowered, and steering stability and wear resistance are lowered when the tire is formed.

  Patent Document 1 discloses a vulcanized rubber composition containing a rubber component, S- (3-aminopropyl) thiosulfuric acid, a filler, a sulfur component, and a vulcanization accelerator, thereby reducing tan δ (60 ° C.) of the rubber composition. Propose to do. However, in this rubber composition, the effect of ensuring the mechanical strength of the rubber composition is not always sufficient, and further improvement has been demanded.

JP 2012-107232 A

An object of the present invention is to provide a method for producing a low rolling resistance, tire rubber composition so as to improve the steering stability and wear resistance in conventional level or higher.

（式中、ｎは１〜１０の整数を表す。）
（２）第一逐次混練工程で得られた第一混合物をゴム成分として１５〜１００重量％含むジエン系ゴム１００重量部に対し、補強性充填剤を３０〜１５０重量部、加硫系配合剤以外の配合剤を配合し、第二混合物として混練する第二逐次混練工程、
（３）第二逐次混練工程で得られた第二混合物に加硫系配合剤を配合し、混合する混合工程。 The manufacturing method of the rubber composition for tires of the present invention that achieves the above object includes at least the steps described in (1) to (3) below.
(1) 0.3 to 5% by weight of S- (aminoalkyl) thiosulfuric acid represented by the following formula (i) or a metal salt thereof is blended with respect to the weight of a rubber component selected from natural rubber and isoprene rubber to reinforce. A first sequential kneading step for pre-kneading as a first mixture not containing a conductive filler,

(In the formula, n represents an integer of 1 to 10.)
(2) 30 to 150 parts by weight of a reinforcing filler and 100 parts by weight of a vulcanizing compound for 100 parts by weight of a diene rubber containing 15 to 100% by weight of the first mixture obtained in the first sequential kneading step. A second sequential kneading step in which a compounding agent other than the above is blended and kneaded as a second mixture,
(3) A mixing step in which a vulcanizing compounding agent is added to and mixed with the second mixture obtained in the second sequential kneading step.

  In the method for producing a tire rubber composition of the present invention, a specific S- (aminoalkyl) thiosulfuric acid or a metal salt thereof is blended with a rubber component composed of natural rubber or isoprene rubber in the first sequential kneading step (1). Since the reinforcing filler is blended and kneaded in the second sequential kneading step (2) without kneading the reinforcing filler, the tan δ (60 ° C.) of the rubber composition is reduced, Mechanical properties such as tensile breaking strength, tensile breaking elongation and rubber hardness can be maintained and improved, and steering stability and wear resistance can be improved to the conventional level.

  The reinforcing filler to be blended in the second mixture preferably contains 30 to 100% by weight of carbon black in 100% by weight of the reinforcing filler. Machines such as tensile breaking strength, tensile breaking elongation, rubber hardness, etc. Characteristics can be improved.

  The rubber composition obtained by the above-described production method is suitable for use in pneumatic tires, and has improved steering stability and wear resistance while reducing rolling resistance and improving fuel economy performance of pneumatic tires. This can be improved as described above.

The method for producing a tire rubber composition of the present invention includes at least three steps including a first sequential kneading step (1), a second sequential kneading step, and a mixing step (3). Moreover, other kneading | mixing processes and / or a mixing process can be added to these processes as needed. In this specification, mixing refers to the operation of mixing the blended ingredients to bring them into a homogeneous state, and kneading means distributing and dispersing the mixture in a homogeneous state, applying shearing force, and heating as necessary. The operation of kneading. Moreover, kneading | mixing and mixing can be performed using the means normally used.

  In the first sequential kneading step (1), the weight of the rubber component is 100% by weight as the first mixture, and 0.3 to 5% by weight of a specific S- (aminoalkyl) thiosulfuric acid or a metal salt thereof is added thereto. And preliminary kneading. In addition, it is necessary that the first mixture does not contain a reinforcing filler. If the first mixture contains a reinforcing filler, a tire rubber composition having the desired effect cannot be obtained.

  The rubber component constituting the first mixture includes at least one of natural rubber and isoprene rubber. As the natural rubber and isoprene rubber, rubbers usually used in rubber compositions for tires can be used. If the rubber component constituting the first mixture is composed of a diene rubber other than natural rubber and isoprene rubber, the desired effect of the present invention cannot be achieved.

  The first mixture is 0.3 to 5% by weight of S- (aminoalkyl) thiosulfuric acid represented by the following formula (i) or a metal salt thereof with respect to 100% by weight of the rubber component consisting of natural rubber and isoprene rubber. %.

（式中、ｎは２〜１０の整数を表す。）

(In the formula, n represents an integer of 2 to 10.)

  In said formula (i), n represents the integer of 1-10, Preferably it is 2-6, More preferably, it is an integer of 3-4. As S- (aminoalkyl) thiosulfuric acid, S- (aminomethyl) thiosulfuric acid, S- (2-aminoethyl) thiosulfuric acid, S- (3-aminopropyl) thiosulfuric acid, S- (4-aminobutyl) Thiosulfuric acid, S- (5-aminopentyl), S- (6-aminohexyl) thiosulfuric acid, S- (7-aminopeptyl) thiosulfuric acid, S- (8-aminooctyl) thiosulfuric acid, S- (9-aminononyl) ) Thiosulfuric acid, S- (10-aminodecyl) thiosulfuric acid. Of these, S- (3-aminopropyl) thiosulfuric acid and S- (4-aminobutyl) thiosulfuric acid are preferable.

  Examples of the metal salt of S- (aminoalkyl) thiosulfuric acid represented by the above formula (i) include lithium ions, sodium ions, potassium ions, cesium ions, cobalt ions, copper ions, and zinc ions as metal ions. it can.

  When the blending amount of S- (aminoalkyl) thiosulfuric acid or a metal salt thereof is less than 0.3% by weight, the tan δ (60 ° C.) of the rubber composition is reduced and the tensile strength at break, tensile elongation at break, rubber hardness The effect of improving the mechanical properties such as is not sufficiently obtained.

  In the first sequential kneading step (1) of the present invention, it is preferable to blend S- (aminoalkyl) thiosulfuric acid represented by the above formula (i) into the first mixture.

  The first mixture is a mixture of a rubber component made of natural rubber or isoprene rubber and the above-described S- (aminoalkyl) thiosulfuric acid, and does not contain a reinforcing filler. Examples of the reinforcing filler include carbon black, silica, clay, aluminum hydroxide, calcium carbonate and the like. When the first mixture contains a reinforcing filler, an effect of reducing tan δ (60 ° C.) and an improvement of mechanical properties such as tensile breaking strength, tensile breaking elongation and rubber hardness were obtained by the present invention. It is inferior to the rubber composition for tires.

  In the present invention, the first sequential kneading step is performed by pre-kneading the above-described first mixture. The pre-kneading of the first mixture may be performed by a normal kneading operation applied to natural rubber and isoprene rubber. The temperature in the first sequential kneading step is preferably 120 to 190 ° C, more preferably 140 to 160 ° C.

  In the second sequential kneading step (2), 30 reinforcing fillers are added to 100 parts by weight of the diene rubber containing 15 to 100% by weight of the first mixture obtained in the first sequential kneading step (1). ~ 150 parts by weight, a compounding agent other than the vulcanizing compounding agent is blended and kneaded as a second mixture.

  The diene rubber constituting the second mixture contains 15 to 100% by weight, preferably 20 to 100% by weight, of the first mixture obtained in the first sequential kneading step (1) as a rubber component. When the content of the first mixture is less than 15% by weight as a rubber component, the effect of reducing tan δ (60 ° C.) of the tire rubber composition and the effect of improving rubber strength are not sufficiently obtained.

  In the second mixture, only the rubber component contained in the first mixture is adjusted to 100% by weight of the diene rubber, or the rubber component contained in the first mixture is mixed with another diene rubber to obtain 100% by weight of the diene rubber. can do. The blending amount of the other diene rubber is 85 to 0% by weight, preferably 80 to 0% by weight. Examples of other diene rubbers include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, and acrylonitrile-butadiene rubber. Of these, natural rubber, isoprene rubber, butadiene rubber, and styrene-butadiene rubber are preferable. These diene rubbers can be used alone or as any blend. Here, natural rubber and isoprene rubber can be blended in both the first mixture and the second mixture as long as the amount of rubber in the first mixture is 15 wt% or more and less than 100 wt%.

  The second mixture contains 30 to 150 parts by weight, preferably 35 to 80 parts by weight of the reinforcing filler, with 100 parts by weight of the above-mentioned diene rubber as 100 parts by weight. When the compounding amount of the reinforcing filler is less than 30 parts by weight, the tensile strength at break, rubber hardness, and wear resistance of the rubber composition are deteriorated. Moreover, when the compounding quantity of a reinforcing filler exceeds 150 weight part, while tan-delta (60 degreeC) will become large, tensile fracture | rupture elongation will fall.

  As described above, examples of the reinforcing filler include carbon black, silica, clay, aluminum hydroxide, calcium carbonate and the like. Of these, carbon black is preferred. The blending amount of carbon black is preferably 30 to 100% by weight in 100% by weight of the reinforcing filler.

  The second mixture contains a compounding agent other than the vulcanizing compounding agent in addition to the diene rubber and the reinforcing filler. Here, the vulcanizing compound includes a vulcanizing agent and a crosslinking agent, a vulcanization accelerator, a crosslinking accelerator, and a vulcanization retarder. Examples of additives other than vulcanizing additives include, for example, various additives generally used in tire rubber compositions such as zinc oxide, stearic acid, antioxidants, various oils, and plasticizers. Can do.

  In the second sequential kneading step, the kneading operation is performed under normal conditions in which the second mixture described above is applied to the mixture of the diene rubber and the reinforcing filler. The temperature in the second sequential kneading step is preferably 120 to 190 ° C, more preferably 140 to 180 ° C.

  The mixing step (3) is a step of blending and mixing a vulcanizing compound in the second mixture obtained in the second sequential kneading step. A vulcanization system compounding agent means the compounding agent mentioned above. In the mixing step, mixing is performed by determining the conditions so that the vulcanizing compound does not cause early vulcanization and crosslinking.

  The tire rubber composition obtained by the production method of the present invention contains 15 to 100% by weight, preferably 25 to 100% by weight, of a rubber component selected from natural rubber and isoprene rubber in 100% by weight of diene rubber. . The total amount of natural rubber and isoprene rubber can be blended in the first mixture. Alternatively, a part of natural rubber and isoprene rubber can be blended in the first mixture such that the rubber component contained in the first mixture is at least 15% by weight in 100% by weight of the diene rubber.

  In the tire rubber composition, 30 to 150 parts by weight, preferably 35 to 80 parts by weight of the reinforcing filler is blended with 100 parts by weight of the diene rubber. The reinforcing filler is not blended in the first sequential kneading step, but blended in the second sequential kneading step. Thus, by not blending the reinforcing filler in the first sequential kneading step, the effect of pre-kneading natural rubber and isoprene rubber with S- (aminoalkyl) thiosulfuric acid or a metal salt thereof is increased, and natural rubber and Isoprene rubber can be hardened, tan δ (60 ° C.) can be reduced, and mechanical strength can be improved.

  The rubber composition for tires of the present invention includes a rubber tread part, an under tread part, a side wall part, a bead filler part, and a cord covering rubber such as a carcass layer, a belt layer, and a belt cover layer, and a run flat tire. Can be suitably used for a crescent-shaped side reinforcing rubber layer, a rim cushion portion, and the like. Since the pneumatic tire using the rubber composition of the present invention for these members has low heat generation during running, it can reduce rolling resistance and improve fuel efficiency. At the same time, by improving the mechanical properties of the rubber composition, it is possible to maintain and improve the handling stability, wear resistance, and durability to the conventional level or higher.

  The rubber master batch of the present invention comprises 0.3 to 5 of S- (aminoalkyl) thiosulfuric acid represented by the above formula (i) or a metal salt thereof with respect to 100% by weight of a rubber component selected from natural rubber and isoprene rubber. It is characterized in that it is blended in a weight percent and kneaded without containing a reinforcing filler. Natural rubber, isoprene rubber and S- (aminoalkyl) thiosulfuric acid or a metal salt thereof are as described above. This rubber masterbatch can be used for a rubber composition such as a tire rubber composition.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  Thirteen types of rubber compositions (Examples 1 to 6, Comparative Example 1) were prepared as shown in Tables 1 and 2 in the three steps including the first sequential kneading step, the second sequential kneading step and the mixing step. ~ 7) were prepared. First, premixing was performed under the conditions of the first sequential kneading step described below with the formulation described in the column “First Blending Step (First Mixture)” to prepare a first mixture. Using the obtained first mixture, kneading was carried out under the conditions of the second sequential kneading step described below with the formulation described in the column of “2nd sequential kneading step (second mixture)”, and the second mixture Was prepared. Using the obtained second mixture, the rubber composition for tire was prepared by mixing under the conditions of the mixing process described below with the compounding described in the “mixing process” column.

  In addition, the description in the column of “first mixture (amount of rubber component)” in “Composition of second sequential kneading step (second mixture)” in Tables 1 and 2 is the description of the first mixture prepared in the first sequential kneading step. The amount of the rubber component described in the parentheses represents the amount of the rubber component. The description of “compounding agent (Table 3)” in the “blending of the second sequential kneading step (second mixture)” in Tables 1 and 2 is a compounding agent other than the vulcanizing compounding compound added in the second sequential kneading step. The individual compounding of the compounding agents other than the vulcanizing compound is shown in Table 3. The amounts of the compounding agents other than the vulcanizing compound described in Table 3 are shown in Tables 1 and 2. It means parts by weight with respect to 100 parts by weight of the diene rubber constituting the rubber composition for tire described.

<Preliminary kneading in the first sequential kneading step>
After pre-mixing natural rubber for 1 minute using a 1.8 L Banbury mixer (97 ° C.), add the compound described in the column of “Composition of first sequential kneading step (first mixture)” in Tables 1 and 2 And pre-kneaded. The total mixing time is 3 minutes and 30 seconds, and the rubber temperature at that time is 152 ° C. The filling rate was 72%.

<Second sequential kneading step>
Using a 1.8 L Banbury mixer, the first mixture obtained in the first sequential process and / or the diene rubber blended in the second sequential kneading process is premixed for 1 minute, and then carbon black or the like “second The compounding agents described in the column of “Sequential kneading step blending (second mixture)” were mixed. The total mixing time of the second sequential kneading is 5 minutes 30 seconds, and the rubber temperature at that time is 162 ° C.

<Mixing process>
The composition described in the column of “Mixing step” in Tables 1 and 2, the second mixture obtained in the second sequential kneading step, the vulcanization accelerator, and sulfur at a temperature of 70 to 90 ° C. in an open roll machine. To obtain a rubber composition for tires.

  The 13 types of rubber compositions thus obtained were each vulcanized at 150 ° C. for 15 minutes in a mold having a predetermined shape to prepare test pieces. The rubber hardness, tensile properties and dynamic viscosity were determined by the following methods. Elasticity (tan δ at 60 ° C.) was evaluated.

Rubber hardness Using the obtained test piece, it was measured at a temperature of 25 ° C. with a durometer type A according to JIS K6253. The obtained results are shown in the column of “Rubber hardness” with the value of Comparative Example 1 being 100. The larger the rubber hardness index, the better the steering stability.

Tensile properties JIS No. 3 dumbbell-shaped test pieces (thickness: 2 mm) were punched out from the obtained test pieces in accordance with JIS K6251 and tested at a pulling speed of 500 mm / min to measure the tensile breaking strength and the tensile breaking elongation. . The obtained results are shown in the “breaking strength” and “breaking elongation” columns as indices with the respective values of Comparative Example 1 as 100. The larger the breaking strength index, the better the steering stability. Moreover, it means that abrasion resistance is excellent, so that the index | exponent of breaking strength is large.

Dynamic viscoelasticity (tan δ at 60 ° C)
Based on JIS K6394, the obtained test piece was subjected to a loss tangent tan δ at a temperature of 60 ° C. under the conditions of an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz, using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho. It was measured. The obtained results are shown in the column of “tan δ (60 ° C.)” as an index with the value of Comparative Example 1 being 100. The smaller the index of tan δ (60 ° C.), the smaller the heat generation, and the smaller the rolling resistance when the tire is made, the better the fuel efficiency.

The types of raw materials used in Tables 1 and 2 are shown below.
NR: natural rubber, RSS # 1
SBR: Styrene-butadiene rubber, Nipol 1502 (without oil-extended rubber) manufactured by Zeon Corporation.
BR: butadiene rubber, Nipol BR1220 manufactured by Nippon Zeon
Carbon black: Seast 7HM manufactured by Tokai Carbon
Organic thiosulfuric acid 1: S- (3-aminopropyl) thiosulfuric acid (manufactured by Sumitomo Chemical Co., Ltd.)
Organic thiosulfuric acid 2: S- (4-aminobutyl) thiosulfuric acid (manufactured by Sumitomo Chemical Co., Ltd.)
Sulfur: Oil processing sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Noxeller NS-P manufactured by Ouchi Shinsei Chemical Co., Ltd.

In addition, the kind of raw material used in Table 3 is shown below.
Aroma oil: Process X-140 manufactured by Japan Energy
Zinc Hana: Zinc Oxide 3 types manufactured by Shodo Chemical Industry Co., Ltd. Stearic acid: NOF Co., Ltd. Beads stearic acid wax: Ouchi Shinsei Chemical Industry Co., Ltd. Sunnock anti-aging agent: Flexis Corporation SANTOFLEX 6PPD

  As is clear from Table 2, it was confirmed that the rubber compositions for tires of Examples 1 to 6 were improved in rubber hardness, tensile breaking strength, tensile breaking elongation, and tan δ (60 ° C.) over the conventional level.

  As is clear from Table 1, the rubber composition of Comparative Example 2 was not subjected to the first sequential kneading step and was not compounded with S- (aminoalkyl) thiosulfuric acid. Therefore, the tensile strength at break and tan δ (60 ° C.) Gets worse. Since the rubber composition of Comparative Example 3 does not perform the first sequential kneading step, the tensile breaking elongation is deteriorated and the effect of reducing tan δ (60 ° C.) is insufficient.

  Since the rubber composition of Comparative Example 4 does not contain S- (aminoalkyl) thiosulfuric acid, the tensile breaking strength deteriorates and the effect of reducing tan δ (60 ° C.) is insufficient. Since the rubber composition of Comparative Example 5 was blended in the second sequential kneading step without blending S- (aminoalkyl) thiosulfuric acid in the first sequential kneading step, the tensile elongation at break deteriorates. Since the rubber composition of Comparative Example 6 was blended with carbon black in the first sequential kneading step, the tensile elongation at break deteriorates.

  In Table 2, the rubber composition of Comparative Example 7 improves the breaking strength and tan δ (60 ° C.) since the compounding amount of the first mixture is less than 15% by weight as the rubber component in the second sequential kneading step. The effect is insufficient.

Claims (3)

The manufacturing method of the rubber composition for tires including the process as described in at least following (1)-(3).
(1) 0.3 to 5% by weight of S- (aminoalkyl) thiosulfuric acid represented by the following formula (i) or a metal salt thereof is blended with respect to the weight of a rubber component selected from natural rubber and isoprene rubber to reinforce. A first sequential kneading step for pre-kneading as a first mixture not containing a conductive filler,

(In the formula, n represents an integer of 2 to 10.)
(2) 30 to 150 parts by weight of a reinforcing filler and 100 parts by weight of a vulcanizing compound for 100 parts by weight of a diene rubber containing 15 to 100% by weight of the first mixture obtained in the first sequential kneading step. A second sequential kneading step in which a compounding agent other than the above is blended and kneaded as a second mixture,
(3) A mixing step in which a vulcanizing compounding agent is added to and mixed with the second mixture obtained in the second sequential kneading step.   2. The rubber composition for tire according to claim 1, wherein the reinforcing filler blended in the second mixture contains 30 to 100% by weight of carbon black in 100% by weight of the reinforcing filler. Method. Natural rubber, relative to 100 wt% of the rubber component selected from isoprene rubber, represented by S- (aminoalkyl) thiosulfuric acid or a metal salt thereof by the following formula (i) will be from 0.3 to 5 wt% blend, reinforcing rubber master batch is in a state free of sex filler.

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