JP4646523B2 - Manufacturing method of rubber composition, rubber composition and pneumatic tire - Google Patents

Description

  The present invention relates to a method for producing a rubber composition, a rubber composition, and a pneumatic tire.

  In recent years, the characteristics required for automobile tires are diverse, such as low fuel consumption, steering stability, wear resistance, riding comfort, and the like, and various ideas have been made to improve these performances.

  For example, in order to improve various performances such as braking performance and driving stability on wet road surfaces at high speeds, by adding silica to styrene butadiene rubber (high styrene SBR) with a high styrene content, Rubber compositions with improved grip performance are known. However, it has been found that the rubber composition blended with silica as described above decreases the rigidity of the rubber and increases the grip performance significantly when the vehicle is repeatedly run. In addition, since silica has a silanol group on the surface, the silica is likely to aggregate together, resulting in insufficient dispersion of silica in rubber, resulting in poor processability such as extrusion.

  Furthermore, in order to further improve the grip performance, a rubber composition is known in which an inorganic compound powder is mixed with carbon black or silica in a diene rubber (see Patent Document 1). However, since inorganic compound powders such as aluminum hydroxide are very fine particles, it is difficult to disperse them in rubber like silica. Especially when used in combination with silica, wet grip performance is not fully exhibited. There is a problem.

JP-A-11-181155

  An object of this invention is to provide the manufacturing method of the rubber composition which is excellent in low-fuel-consumption property and wet grip performance, the rubber composition obtained by this manufacturing method, and the pneumatic tire which consists of this rubber composition.

The present invention relates to the following general formula kM ₁ · xSiO _y · zH ₂ O with respect to 100 parts by weight of a rubber component made of a diene rubber.
Wherein M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 0 10 is an integer, y is an integer of 2 to 5, and z is an integer of 0 to 10.)
A method for producing a rubber composition containing 5 to 150 parts by weight of an inorganic compound powder represented by formula (1) and carbon black and / or silica,
The present invention relates to a method for producing a rubber composition, comprising: (1) a step of mixing the rubber component with carbon black and / or silica; and (2) a step of mixing the inorganic compound powder.

  In step (1) and / or (2) of the production method, it is preferable to mix 1 to 20 parts by weight of the silane coupling agent with respect to 100 parts by weight of silica.

  Moreover, this invention relates to the rubber composition obtained by the said manufacturing method.

  Furthermore, the present invention relates to a pneumatic tire having a tread made of the rubber composition.

  According to the present invention, after mixing a rubber component composed of a diene rubber and a filler other than an inorganic compound powder, the processability is improved by mixing the inorganic compound powder, and obtained from the production method. In the pneumatic tire made of the rubber composition, low fuel consumption and wet grip performance can be improved.

  The rubber composition of the present invention comprises a rubber component, an inorganic compound powder, and carbon black and / or silica.

  A diene rubber is used as the rubber component. Diene rubbers include natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene. Examples thereof include rubber (NBR) and butyl rubber (IIR). These rubbers may be used alone or in combination of two or more.

  Among the rubber components, SBR is particularly preferable from the viewpoint of grip performance, and the rubber component preferably contains 10% by weight or more of SBR. When the SBR is less than 10% by weight, there is a tendency that sufficient grip performance cannot be obtained.

  The inorganic compound powder used in the present invention is represented by the following general formula.

kM ₁ xSiO _y zH ₂ O
In the formula, M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 10 , Y is an integer of 2 to 5, and z is an integer of 0 to 10.

  Examples of the inorganic compound powder represented by the general formula include alumina, alumina hydrate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, talc, titanium white, titanium black, calcium oxide, calcium hydroxide, and aluminum magnesium oxide. Clay, pyrophyllite, bentonite, aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate and the like. These inorganic compound powders may be used alone or in combination of two or more. Of these inorganic compound powders, aluminum hydroxide, magnesium hydroxide, clay, alumina, alumina hydrate and the like are preferable from the viewpoint of further improving grip performance.

  The average particle size of the inorganic compound powder is preferably 0.01 to 10 μm. When the average particle size of the inorganic compound powder is less than 0.01 μm, not only the workability during rubber kneading is lowered, but also the dispersibility tends to be deteriorated, and if it exceeds 10 μm, the wear resistance tends to be lowered. is there. From the viewpoint of workability, dispersibility, and wear resistance, the lower limit of the average particle diameter of the inorganic compound powder is more preferably 0.02 μm, and the upper limit is more preferably 8 μm.

  The compounding quantity of inorganic compound powder is 5-150 weight part with respect to 100 weight part of rubber components. When the compounding amount of the inorganic compound powder is less than 5 parts by weight, the effect of improving the wet grip performance is small, and when it exceeds 150 parts by weight, the wear resistance is lowered and sufficient wet grip performance cannot be obtained. The lower limit of the amount of the inorganic compound powder is preferably 10 parts by weight. Moreover, as an upper limit, it is preferable that it is 120 weight part, and it is more preferable that it is 100 weight part.

The carbon black used in the present invention preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 70 to 200 m ² / g. Moreover, the thing of 70-200 ml / 100g of dibutyl phthalate (DBP) oil absorption is preferable. When the N ₂ SA of carbon black is less than 70 m ² / g or the DBP oil absorption is less than 70 ml / 100 g, it is difficult to obtain sufficient reinforcement and wear resistance. On the other hand, when N ₂ SA exceeds 200 m ² / g or DBP oil absorption exceeds 200 ml / 100 g, the dispersibility tends to decrease and the exothermic property of the rubber composition tends to increase. From the viewpoint of reinforcement, wear resistance and heat generation, the lower limit of N ₂ SA of carbon black is more preferably 80 m ² / g, and the upper limit is more preferably 180 m ² / g. The lower limit of the DBP oil absorption is more preferably 80 ml / 100 g, and the upper limit is more preferably 170 ml / 100 g. Examples of such carbon black include HAF, ISAF, and SAF, but are not particularly limited.

  The compounding amount of carbon black is preferably 5 to 150 parts by weight with respect to 100 parts by weight of the rubber component. The lower limit of the amount is more preferably 10 parts by weight, and the upper limit is more preferably 120 parts by weight. If the blending amount of the carbon black is less than 5 parts by weight, there is a tendency that reinforcing properties and abrasion resistance cannot be obtained, and if it exceeds 150 parts by weight, dispersibility and workability tend to be deteriorated.

  The silica used in the present invention includes silica produced by a wet method or a dry method, but is not particularly limited.

The silica preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 100 to 300 m ² / g. The lower limit of N ₂ SA is more preferably 120 m ² / g, and the upper limit is more preferably 280 m ² / g. If the N ₂ SA of silica is less than 100 m ² / g, the reinforcing effect is small, and if it exceeds 300 m ² / g, the dispersibility tends to decrease and the exothermic property of the rubber composition tends to increase.

  It is preferable that the compounding quantity of a silica is 5-150 weight part with respect to 100 weight part of rubber components. As a minimum of a compounding quantity, it is more preferable that it is 10 weight part, and it is further more preferable that it is 15 weight part. Moreover, as an upper limit of a compounding quantity, it is more preferable that it is 120 weight part, and it is further more preferable that it is 100 weight part. If the amount of silica is less than 5 parts by weight, sufficient low heat build-up and wet grip performance tend not to be obtained, and if it exceeds 150 parts by weight, workability and workability tend to be lowered.

  The total amount of the inorganic compound powder, carbon black and silica is preferably 10 to 160 parts by weight with respect to 100 parts by weight of the rubber component. The lower limit of the total amount is more preferably 20 parts by weight, and the upper limit is more preferably 150 parts by weight. If the total amount is less than 10 parts by weight, the reinforcing property and wear resistance tend to decrease. If the total amount exceeds 160 parts by weight, not only the dispersibility and workability are deteriorated but also the heat generation of the rubber composition is increased. Tend to.

  The rubber composition of the present invention may contain a silane coupling agent. The silane coupling agent that can be suitably used in the present invention can be any silane coupling agent conventionally used in combination with a silica filler. Specifically, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) Tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide Bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3- Riethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide Bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxy Silylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolylte Sulfide systems such as rasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltri Mercapto series such as ethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; Vinyl series such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltri Amino such as methoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane Glycidoxy systems such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; 3-nitro Nitro compounds such as propyltrimethoxysilane and 3-nitropropyltriethoxysilane; such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane Examples include chloro. Bis (3-triethoxysilylcypropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, 3-mercaptopropyltrimethoxysilane, and the like are preferably used because of the effect of adding a coupling agent and cost. These silane coupling agents may be used alone or in combination of two or more.

  It is preferable that the compounding quantity of a silane coupling agent is 1-20 weight part with respect to 100 weight part of silica. If the blending amount of the silane coupling agent is less than 1 part by weight, the effect of blending the silane coupling agent tends to be insufficient, and if it exceeds 20 parts by weight, the cost is increased, but the coupling effect is high. Not much is obtained and the reinforcement and wear resistance tend to decrease. From the viewpoint of the dispersion effect and the coupling effect, the lower limit of the amount of the silane coupling agent is more preferably 2 parts by weight, and the upper limit is more preferably 15 parts by weight.

  The rubber composition of the present invention is produced by mixing the rubber component and carbon black and / or silica in the step (1) and then adding and mixing the inorganic compound powder in the step (2). There is no restriction | limiting in particular regarding conditions, such as temperature, in both a process (1) and a process (2), It is preferable to mix at 110-180 degreeC. Even if inorganic compound powder is mixed with carbon black or silica at the same time, good fuel economy and wet grip performance can be obtained, but inorganic compound powder should be mixed in a later process than other fillers. Thus, a better wet grip performance can be obtained.

  When only the rubber component and the carbon black are mixed in the step (1), there is no limitation on the kneading temperature and the kneading is usually performed at 130 to 170 ° C. for 2 to 10 minutes.

  When mixing silica in the step (1), it is preferable to knead at a relatively low temperature of 130 to 150 ° C. for 2 to 10 minutes in order to suppress rubber burning due to silica gelation.

  When mixing the inorganic compound powder in the step (2), it is preferable to knead at a low temperature of 100 to 150 ° C. for 2 to 10 minutes for the purpose of well dispersing the inorganic compound powder.

  Although it is possible to mix a silane coupling agent in both steps (1) and (2) or in any one of them, it is preferable to mix in step (1) in which mixing is performed simultaneously with silica.

  The kneading temperature can be controlled, for example, by setting the rotational speed of a Banbury mixer or the like used for kneading, the filling rate of the material to be added, the kneading time, and the ram raising time.

  In addition to the rubber component, inorganic compound powder, carbon black, silica, and silane coupling agent, the rubber composition of the present invention includes a softener, an anti-aging agent, a vulcanizing agent, and a vulcanization accelerator as necessary. A compounding agent used in a normal rubber industry such as a vulcanization accelerating aid can be blended. Compounding agents other than the vulcanizing agent and the vulcanization accelerator can be mixed in the step (1) and / or (2). It is preferable that the vulcanizing agent and the vulcanization accelerator are mixed in the final stage after mixing the compounding agent.

  The pneumatic tire of the present invention is produced by a usual method using the rubber composition of the present invention. That is, the rubber composition of the present invention blended with the above-mentioned various compounding agents as necessary is extruded into a tread member at an unvulcanized stage, and pasted and molded on a tire molding machine by a usual method. Form an unvulcanized tire. This unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire. The pneumatic tire of the present invention thus obtained is excellent in low fuel consumption and wet grip performance.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these.

The chemicals used in the examples and comparative examples are collectively shown below.
SBR: SBR1502 manufactured by JSR Corporation (styrene unit amount: 23.5% by weight)
Carbon black: Show black N220 manufactured by Showa Cabot Co., Ltd. (N ₂ SA: 125 m ² / g, DBP oil absorption: 115 ml / 100 g)
Silica: Ultrazil VN3 manufactured by Degussa (N ₂ SA: 210 m ² / g)
Aluminum hydroxide: Heidilite H-43 (Al (OH) ₃ , average particle size: 0.5 to 2 μm, manufactured by Showa Denko KK)
Clay: Crown clay manufactured by South Eastern (Al ₂ O ₃ .2SiO ₂ , particle diameter: 2 μm or less)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Aroma oil: JOMO process X140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Stearic acid wax manufactured by Nippon Oil & Fats Co., Ltd .: Sunnock wax manufactured by Ouchi Shinsei Chemical Co., Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Tsurumi Chemical Co., Ltd. Powdered sulfur vulcanization accelerator TBBS manufactured by Nouchira NS (N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Example 1 , Reference Examples 2 to 4 and Comparative Examples 1 to 4
According to the blending contents shown in Table 1, they were kneaded as shown below.

In Example 1 and Reference Examples 2 to 4 , first, SBR and carbon black and / or silica, a silane coupling agent, and aroma oil were kneaded for 4 minutes at 150 ° C., and then aluminum hydroxide or clay, anti-aging The agent, stearic acid and zinc oxide were added and kneaded at 140 ° C. for 4 minutes. Furthermore, sulfur and a vulcanization accelerator were added and kneaded at 50 ° C. for 4 minutes.

  On the other hand, in Comparative Examples 1 to 4, all components other than sulfur and the vulcanization accelerator were collectively kneaded at 150 ° C. for 8 minutes, and further, sulfur and the vulcanization accelerator were added, and then at 50 ° C. for 4 minutes. Kneaded.

  Each of the resulting blends was press vulcanized at 170 ° C. for 20 minutes to obtain vulcanizates, which were tested for the following characteristics.

(Processability)
The unvulcanized rubber composition was measured at 130 ° C. according to the Mooney viscosity measurement method defined in JIS K6300.
The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 was set to 100, and indexed by the following calculation formula. The larger the index, the lower the Mooney viscosity and the better the processability.
(Mooney viscosity index) = (ML _{1 + 4} of Comparative Example 1) ÷ (ML _{1 + 4 of} each formulation) × 100

(Abrasion test)
With a Lambourn abrasion tester, the Lambourne wear amount was measured under the conditions of a temperature of 20 ° C., a slip rate of 20% and a test time of 5 minutes, and the volume loss of each formulation was calculated. Expressed as an index using the formula. The higher the index, the better the wear resistance.
(Abrasion index) = (loss amount of Comparative Example 1) / (loss amount of each formulation) × 100

(Rolling resistance index)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each formulation was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2%. The index was expressed by the following formula. The larger the index, the better the rolling resistance characteristics.
(Rolling resistance index) = (tan δ of Comparative Example 1) ÷ (tan δ of each formulation) × 100

(Wet skid test)
Using a portable skid tester manufactured by Stanley, the measurement was performed according to the method of ASTM E303-83, and the measured value of Comparative Example 1 was set to 100 and indicated by the following formula. The larger the index, the better the wet skid performance.
(Wet skid index) = (Numerical value of each formulation) / (Numerical value of Comparative Example 1) × 100

  Each test result is shown in Table 1.

Claims (2)

The following general formula: kM ₁ · xSiO _y · zH ₂ O
Wherein M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 0 10 is an integer, y is an integer of 2 to 5, and z is an integer of 0 to 10.)
A method for producing a rubber composition comprising 20 to 150 parts by weight of an inorganic compound powder represented by formula (1) and carbon black and / or silica,
(1) a step of mixing the rubber component with carbon black and / or silica, and (2) a step of mixing the inorganic compound powder at a temperature of 100 ° C. or higher .
A method for producing a rubber composition, comprising:
Further, Ri Do the step of mixing a vulcanizing agent and the vulcanization accelerator after step (2),
A method for producing a rubber composition, wherein the inorganic compound powder is at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide and alumina hydrate having an average particle size of 0.01 to 10 µm . The method for producing a rubber composition according to claim 1, wherein in step (1) and / or (2), 1 to 20 parts by weight of the silane coupling agent is mixed with 100 parts by weight of silica.