JP2015124309A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having at least one member that is improved in various performances such as fuel economy, processability, thermal aging resistance, degradation-resistant performance, flex crack growth resistance, rubber strength, adhesion strength, fracture strength, run-flat durability and air permeation resistance in a well balanced manner.SOLUTION: The pneumatic tire includes at least one member selected from a group consisting of an under tread, sidewall, wing, ply topping, breaker topping, clinch apex, bead apex, sidewall reinforcing layer and inner liner, manufactured by using the following rubber composition. The rubber composition comprises a modified natural rubber that is highly purified and adjusted to have a pH of 2 to 7, carbon black and/or a white filler, and a silane coupling agent represented by formula (S1) below.

Description

The present invention is selected from the group consisting of an under tread, a sidewall, a wing, a bright topping, a break topping, a clinch apex, a bead apex, a side wall reinforcing layer, and an inner liner produced using a predetermined rubber composition. The present invention relates to a pneumatic tire having at least one member.

In recent years, there has been a great demand for lower fuel consumption for tires, and tread improvements have mainly been made. Undertread, sidewalls, wings, pretopping, breaker topping, clinch apex, bead apex, sidewall reinforcement Lower fuel consumption is also required for the layer and inner liner. Since natural rubber is frequently used for these members, it is necessary to promote the reduction in fuel consumption of natural rubber in order to reduce the fuel consumption of the entire tire.

For example, Patent Document 1 discloses a method of adding a surfactant to natural rubber latex and performing a cleaning process as fuel efficiency reduction by modifying natural rubber. However, although the protein and gel content can be reduced to some extent by this method, it is not a sufficient level and further reduction of tan δ is desired. Also, tire rubbers are required to have performance such as heat aging resistance, but the method of Patent Document 1 is insufficient in heat resistance, and an improvement in both low fuel consumption and heat aging resistance is desired. Yes.

In addition, natural rubber has a high Mooney viscosity compared to other synthetic rubbers and has poor processability, and is usually used after mastication with a masticant added to reduce Mooney viscosity. The nature is bad. Furthermore, the molecular chain of natural rubber is cleaved by mastication, so that there is a problem that characteristics (such as good fuel efficiency) of the high molecular weight polymer inherent to natural rubber are lost.

On the other hand, in recent years, the wear resistance of tires has been improved and the period of use in the market has been prolonged, so the tires have long-term damage and deterioration resistance, bending crack growth resistance, rubber strength, adhesive strength, It is also required to improve various properties such as breaking strength, run flat durability, and air permeation resistance.

As described above, the various tire members described above have low fuel consumption, workability, heat aging resistance, and deterioration resistance, flex crack growth resistance, rubber strength, adhesive strength, break strength, run-flat durability, air resistance. Further improvements in various properties such as permeability are desired.

Japanese Patent No. 3294901

The present invention solves the above-mentioned problems, and has low fuel consumption, processability, heat aging resistance, and deterioration resistance, flex crack growth resistance, rubber strength, adhesive strength, break strength, run flat durability, and air permeation resistance. At least one member selected from the group consisting of undertread, sidewall, wing, pretapping, breaker topping, clinch apex, bead apex, side wall reinforcing layer and inner liner with improved performance in a balanced manner It aims at providing the pneumatic tire which has.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ The present invention comprises a modified natural rubber having a high purity and a pH adjusted to 2 to 7, carbon black and / or a white filler, and a silane coupling agent represented by the following formula (S1): At least one member selected from the group consisting of an under tread, a sidewall, a wing, a pretopping, a break cartping, a clinch apex, a bead apex, a sidewall reinforcing layer and an inner liner, produced using the rubber composition comprising It relates to a pneumatic tire having

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

The modified natural rubber is preferably obtained by removing the non-rubber component of the natural rubber and then treating with an acidic compound, and the pH is 2-7.

The modified natural rubber is obtained by washing saponified natural rubber latex and further treating with an acidic compound, and preferably has a pH of 2-7.

The modified natural rubber is preferably obtained by washing deproteinized natural rubber latex and further treating with an acidic compound, and having a pH of 2-7.

The phosphorus content of the modified natural rubber is preferably 200 ppm or less.

The nitrogen content of the modified natural rubber is preferably 0.15% by mass or less.

The pH is measured by cutting the modified natural rubber into 2 mm squares of each side and immersing in distilled water, extracting at 90 ° C. for 15 minutes while irradiating with microwaves, and measuring the immersion water using a pH meter. It is preferable that it is a value obtained.

The modified natural rubber has a Mooney viscosity ML (1 + 4) of 130 ° C. measured in accordance with JIS K 6300: 2001-1 and a heat aging index represented by the following formula of 75 to 120%. Is preferred.

The white filler is preferably silica.

It is preferable that content of the said silane coupling agent is 0.1-20 mass parts with respect to 100 mass parts of total content of the said carbon black and a white filler.

The modified natural rubber is preferably produced without going through a mastication step.

According to the present invention, a rubber composition comprising a modified natural rubber having a high purity and a pH adjusted to 2 to 7, a carbon black and / or white filler, and a specific silane coupling agent. A pneumatic tire having at least one member selected from the group consisting of an under tread, a sidewall, a wing, a pretapping, a break topping, a clinch apex, a bead apex, a side wall reinforcing layer, and an inner liner produced by using Therefore, it balances various performances such as fuel efficiency, workability, heat aging resistance, deterioration resistance, flex crack growth resistance, rubber strength, adhesive strength, breaking strength, run flat durability, and air permeation resistance. It can be improved well.

The pneumatic tire of the present invention is a rubber composition comprising a modified natural rubber that is highly purified and has a pH adjusted to 2 to 7, carbon black and / or white filler, and a specific silane coupling agent. It has at least one member selected from the group consisting of an under tread, a side wall, a wing, a pree tapping, a break topping, a clinch apex, a bead apex, a side wall reinforcing layer and an inner liner.

First, the rubber composition constituting the undertread and the like will be described.
The rubber composition includes a modified natural rubber that is highly purified and has a pH adjusted to 2 to 7, carbon black and / or a white filler, and a specific silane coupling agent. By using the modified natural rubber as a rubber component and a specific compound as a silane coupling agent, the various performances are synergistically improved, and the performance balance is remarkably improved.

The modified natural rubber is highly purified and has a pH adjusted to 2-7.
Non-rubber components such as proteins and phospholipids are removed to improve the purity, and the modified natural rubber controls the pH of the rubber to an appropriate value, resulting in low fuel consumption, processability, deterioration resistance, and bending resistance. Crack growth, rubber strength, adhesive strength, breaking strength, run flat durability, and air permeation resistance are improved. Also, the removal of non-rubber components and the rubber becoming basic or strongly acidic facilitates the deterioration of the rubber, but the adjustment of the pH of the rubber to a predetermined range suppresses the decrease in molecular weight during storage. Therefore, good heat aging resistance can be obtained. As a result, it is possible to prevent the rubber physical properties from being lowered in the kneading step and to improve the dispersibility of the filler, and synergistically improve the performance balance of the various performances.

Here, high purification means removing impurities such as phospholipids and proteins other than natural polyisoprenoid components. Natural rubber has a structure in which the isoprenoid component is covered with the impurity component. By removing the component, the structure of the isoprenoid component changes, and the interaction with the compounding agent changes, resulting in energy. It is presumed that loss can be reduced, durability can be improved, and a better rubber composition can be obtained.

The modified natural rubber having a high purity and a pH adjusted to 2 to 7 may be a modified natural rubber having a high purity by reducing the amount of non-rubber components and having a rubber pH of 2 to 7. Specifically, (1) modified natural rubber obtained by removing non-rubber components of natural rubber and then treating with an acidic compound, and having a pH of 2 to 7, (2) Ken Natural rubber latex is washed and further treated with an acidic compound, modified natural rubber having a pH of 2 to 7, and (3) deproteinized natural rubber latex is washed and further treated with an acidic compound. And modified natural rubber having a pH of 2 to 7.

As described above, the modified natural rubber can be prepared by a method of washing a saponified natural rubber latex or a deproteinized natural rubber latex with distilled water or the like and further treating with an acidic compound. It is important to lower the pH value by shifting to the acidic side by treatment with an acidic compound. Usually, the pH of distilled water is not 7.00 and is about 5 to 6, but in this case, it is important to reduce the pH value to the acidic side from 5 to 6 by treatment with an acidic compound. Become. Specifically, it is preferable to lower the pH value by 0.2 to 2 by treatment with an acidic compound, rather than the pH value of water used for washing.

The modified natural rubber has a pH of 2-7, preferably 3-6, more preferably 4-6. By adjusting within the above range, a decrease in heat aging resistance is prevented, and the various performances can be remarkably improved. The pH of the modified natural rubber is cut into a size of 2 mm square or less on each side, soaked in distilled water, extracted at 90 ° C. for 15 minutes while irradiating with microwaves, and the soaked water was measured using a pH meter. Specifically, it is measured by the method described in the examples described later. Here, regarding extraction, even if it is extracted for 1 hour with an ultrasonic cleaner or the like, the water-soluble component cannot be completely extracted from the inside of the rubber, so the internal pH cannot be accurately determined. The present inventor has found that the substance of rubber can be known by extracting.

The modified natural rubber is purified by various methods such as (1) to (3). For example, the phosphorus content in the modified natural rubber is preferably 200 ppm or less, more preferably It is 150 ppm or less. If it exceeds 200 ppm, the Mooney viscosity may increase during storage and processability may deteriorate, or tan δ may increase and fuel economy may not be improved. The phosphorus content can be measured by a conventional method such as ICP emission analysis. Phosphorus is considered to be derived from phospholipids contained in natural rubber.

When the modified natural rubber contains an artificial anti-aging agent, the nitrogen content after being immersed in acetone at room temperature (25 ° C.) for 48 hours is preferably 0.15% by mass or less, More preferably, it is 0.1 mass% or less. If it exceeds 0.15% by mass, the Mooney viscosity may increase during storage, resulting in poor processability, and the effect of improving fuel economy may not be sufficiently obtained. Highly purified natural rubber may be deteriorated by long-term storage because the natural anti-aging component, which is said to be inherent to natural rubber, has been removed. Therefore, an artificial anti-aging agent may be added. The nitrogen content is a measured value after removing an artificial anti-aging agent in rubber by extraction with acetone. The nitrogen content can be measured by a conventional method such as Kjeldahl method or trace nitrogen meter. Nitrogen is derived from proteins and amino acids.

The modified natural rubber preferably has a Mooney viscosity ML (1 + 4) 130 ° C. measured in accordance with JIS K 6300: 2001-1 of 75 ° C. or less, more preferably 40 to 75, still more preferably 45 to 75. Particularly preferred is 50 to 70, most preferred 55 to 65. By being 75 or less, the kneading normally required before rubber kneading becomes unnecessary. Therefore, the modified natural rubber produced without the mastication step can be suitably used as a compounding material for the rubber composition. On the other hand, when it exceeds 75, it is necessary to masticate before use, and there is a tendency for exclusive use of equipment, loss of electricity and thermal energy, and the like.

The modified natural rubber is preferably a rubber having a heat aging index represented by the following formula of 75 to 120% with respect to the Mooney viscosity ML (1 + 4) 130 ° C.

The heat aging index represented by the above formula is more preferably 80 to 115%, still more preferably 85 to 110%. Various methods have been reported for evaluating the heat aging resistance of rubber. By using the method of evaluating the rate of change before and after heat treatment at 80 ° C. for 18 hours for Mooney viscosity ML (1 + 4) at 130 ° C., tire production is possible. It is possible to accurately evaluate heat aging resistance at times and when using tires. Here, if it is within the above range, excellent heat aging resistance can be obtained, and the performance balance of the various performances can be remarkably improved.

The modified natural rubber having a high purity such as (1) to (3) and having a pH adjusted to 2 to 7 is (Production method 1) Step 1-1 of saponifying natural rubber latex; A production method comprising a step 1-2 for washing the saponified natural rubber latex and a step 1-3 for treating with the acidic compound; (Production method 2) a step 2-1 for deproteinizing the natural rubber latex; It can be prepared by a production method including a step 2-2 for washing rubber latex and a step 2-3 for treating with an acidic compound.

[Production method 1]
(Step 1-1)
In step 1-1, natural rubber latex is saponified. Thereby, saponified natural rubber latex in which phospholipids and proteins in the rubber are decomposed and non-rubber components are reduced is prepared.

Natural rubber latex is collected as sap of natural rubber trees such as Hevea, and contains rubber, water, proteins, lipids, inorganic salts, etc., and the gel content in rubber is based on the complex presence of various impurities. It is considered a thing. In the present invention, as natural rubber latex, raw latex (field latex) produced by tapping Hevea tree, or concentrated latex concentrated by centrifugal separation or creaming (refined latex, high ammonia to which ammonia is added by a conventional method) Latex, zinc oxide, TMTD, and LATZ latex stabilized with ammonia can be used.

As a method for the saponification treatment, for example, the method described in JP 2010-138359 A and JP 2010-174169 A can be suitably performed, and specifically, the following method can be used.

The saponification treatment can be performed by adding an alkali and, if necessary, a surfactant to natural rubber latex and allowing to stand at a predetermined temperature for a certain period of time. Stirring may be performed as necessary.

The alkali used for the saponification treatment is preferably sodium hydroxide or potassium hydroxide, but is not limited thereto. The surfactant is not particularly limited, and examples include known anionic surfactants such as polyoxyethylene alkyl ether sulfate salts, nonionic surfactants, and amphoteric surfactants. Anionic surfactants such as polyoxyethylene alkyl ether sulfates are preferred because they can be saponified. In the saponification treatment, the addition amount of alkali and surfactant, the temperature and time of the saponification treatment may be appropriately set.

(Step 1-2)
In step 1-2, the saponified natural rubber latex obtained in step 1-1 is washed. By the washing, non-rubber components such as proteins are removed.

Step 1-2 includes, for example, aggregating the saponified natural rubber latex obtained in Step 1-1 to produce an agglomerated rubber, and then treating the obtained agglomerated rubber with a basic compound and further washing. Can be implemented. Specifically, after the agglomerated rubber is produced, the non-rubber component can be removed by diluting with water and transferring the water-soluble component to the aqueous layer and removing the water, and further by treating with a basic compound after agglomeration. Non-rubber components confined in the rubber during agglomeration can be redissolved. Thereby, non-rubber components such as protein strongly adhered to the agglomerated rubber can be removed.

Examples of the aggregating method include a method of adjusting the pH by adding an acid such as formic acid, acetic acid or sulfuric acid, and further adding a polymer flocculant as necessary. Thereby, not a large aggregate but a granular rubber having a diameter of about 20 mm is formed from a diameter of several mm to 1 mm or less, and proteins and the like are sufficiently removed by the basic compound treatment. The pH is preferably adjusted in the range of 3.0 to 5.0, more preferably 3.5 to 4.5.

Examples of polymer flocculants include cationic polymer flocculants such as methyl chloride quaternary salt polymer of dimethylaminoethyl (meth) acrylate, anionic polymer flocculants such as acrylate polymer, and acrylamide polymer. Nonionic polymer flocculants such as, and amphoteric polymer flocculants such as dimethylaminoethyl (meth) acrylate methyl chloride quaternary salt-acrylate copolymer. The addition amount of the polymer flocculant can be selected as appropriate.

Next, the resulting agglomerated rubber is treated with a basic compound. Here, although it does not specifically limit as a basic compound, A basic inorganic compound is suitable from the point of removal performance, such as protein.

Examples of basic inorganic compounds include metal hydroxides such as alkali metal hydroxides and alkaline earth metal hydroxides; metal carbonates such as alkali metal carbonates and alkaline earth metal carbonates; alkali metal hydrogen carbonates and the like Metal phosphates such as alkali metal phosphates; metal acetates such as alkali metal acetates; metal hydrides such as alkali metal hydrides; ammonia and the like.

Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. Examples of the alkaline earth metal hydroxide include magnesium hydroxide, calcium hydroxide, and barium hydroxide. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of the alkaline earth metal carbonate include magnesium carbonate, calcium carbonate, barium carbonate and the like. Examples of the alkali metal hydrogen carbonate include lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Examples of the alkali metal phosphate include sodium phosphate and sodium hydrogen phosphate. Examples of the alkali metal acetate include sodium acetate and potassium acetate. Examples of the alkali metal hydride include sodium hydride and potassium hydride.

Of these, metal hydroxides, metal carbonates, metal hydrogen carbonates, metal phosphates, and ammonia are preferable, alkali metal carbonates, alkali metal hydrogen carbonates, and ammonia are more preferable, and sodium carbonate and sodium hydrogen carbonate are more preferable. preferable. The said basic compound may be used independently and may use 2 or more types together.

The method for treating the agglomerated rubber with the basic compound is not particularly limited as long as the agglomerated rubber is brought into contact with the basic compound. For example, the method of immersing the agglomerated rubber in an aqueous solution of the basic compound, And a method of spraying an aqueous solution of the active compound. An aqueous solution of a basic compound can be prepared by diluting and dissolving each basic compound with water.

The content of the basic compound in 100% by mass of the aqueous solution is preferably 0.1% by mass or more, more preferably 0.3% by mass or more. If it is less than 0.1% by mass, the protein may not be sufficiently removed. The content is preferably 10% by mass or less, more preferably 5% by mass or less. If it exceeds 10% by mass, a large amount of basic compound is required, but the amount of proteolysis does not increase, and the efficiency tends to be poor.

As pH of the aqueous solution of the said basic compound, 9-13 are preferable and 10-12 are more preferable from the point of processing efficiency.

Although the said processing temperature should just be selected suitably, Preferably it is 10-50 degreeC, More preferably, it is 15-35 degreeC. Moreover, processing time is 1 minute or more normally, Preferably it is 10 minutes or more, More preferably, it is 30 minutes or more. If it is less than 1 minute, the effects of the present invention may not be obtained satisfactorily. The upper limit is not limited, but is preferably 48 hours or less, more preferably 24 hours or less, and still more preferably 16 hours or less from the viewpoint of productivity.

After the basic compound treatment, a washing treatment is performed. By this washing treatment, it is possible to sufficiently remove non-rubber components such as proteins trapped in the rubber at the time of aggregation, and at the same time sufficiently remove not only the surface of the aggregated rubber but also the basic compounds present inside. . In particular, by removing the basic compound remaining in the entire rubber in the washing step, it becomes possible to sufficiently treat the entire rubber with an acidic compound described later, and not only the surface of the rubber but also the internal pH is 2 Can be adjusted to ~ 7.

As the washing method, a non-rubber component contained in the whole rubber, means capable of sufficiently removing the basic compound can be suitably used, for example, a method of diluting the rubber with water and washing, followed by centrifugation, There is a method in which the rubber is floated by standing, and the rubber component is taken out by discharging only the aqueous phase. The number of washings can be any number of times that can reduce the amount of non-rubber components such as proteins and basic compounds to a desired amount. However, the washing is performed by adding 1000 mL of water to 300 g of dry rubber and stirring and dehydrating. If it is the method of repeating a cycle, 3 times (3 cycles) or more are preferable, 5 times (5 cycles) or more are more preferable, and 7 times (7 cycles) or more are still more preferable.

The washing treatment is preferably carried out until the phosphorus content in the rubber is 200 ppm or less and / or the nitrogen content is 0.15 mass% or less. The various performances are improved by sufficiently removing phospholipids and proteins by the washing treatment.

(Step 1-3)
In Step 1-3, the washed rubber obtained in Step 1-2 is treated with an acidic compound. As described above, by performing the treatment, the pH of the entire rubber is adjusted to 2 to 7, and a modified natural rubber having excellent various performances can be provided. In addition, although there exists a tendency for heat aging resistance to fall resulting from the process of a basic compound, such a problem is prevented by further processing with an acidic compound, and favorable heat aging resistance is obtained.

The acidic compound is not particularly limited, and inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, metaphosphoric acid, boric acid, boronic acid, sulfanilic acid, sulfamic acid; formic acid, acetic acid, glycolic acid, oxalic acid, propion Acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, methanesulfonic acid, Itaconic acid, benzenesulfonic acid, toluenesulfonic acid, naphthalenedisulfonic acid, trifluoromethanesulfonic acid, styrenesulfonic acid, trifluoroacetic acid, barbituric acid, acrylic acid, methacrylic acid, cinnamic acid, 4-hydroxybenzoic acid, aminobenzoic acid , Naphthalene disulfonic acid, hydroxybenze Examples include organic acids such as sulfonic acid, toluenesulfinic acid, benzenesulfinic acid, α-resorcinic acid, β-resorcinic acid, γ-resorcinic acid, gallic acid, phloroglicin, sulfosalicylic acid, ascorbic acid, erythorbic acid, and bisphenolic acid. It is done. Of these, acetic acid, sulfuric acid, formic acid and the like are preferable. The said acidic compound may be used independently and may use 2 or more types together.

The method of treating the agglomerated rubber with an acid is not particularly limited as long as the agglomerated rubber is brought into contact with the acidic compound. For example, a method of immersing the agglomerated rubber in an aqueous solution of the acidic compound, an aqueous solution of the acidic compound in the agglomerated rubber The method of spraying etc. are mentioned. An aqueous solution of an acidic compound can be prepared by diluting and dissolving each acidic compound with water.

The content of the acidic compound in 100% by mass of the aqueous solution is not particularly limited, but the lower limit is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and the upper limit is preferably 15% by mass or less. More preferably, it is 10 mass% or less, More preferably, it is 5 mass% or less. When the content is within the above range, good heat aging resistance can be obtained.

Although the said processing temperature should just be selected suitably, Preferably it is 10-50 degreeC, More preferably, it is 15-35 degreeC. The treatment time is usually preferably 3 seconds or more, more preferably 10 seconds or more, and further preferably 30 seconds or more. If it is less than 3 seconds, it cannot be sufficiently neutralized and the effects of the present invention may not be obtained satisfactorily. Although there is no restriction | limiting in an upper limit, From the point of productivity, Preferably it is 24 hours or less, More preferably, it is 10 hours or less, More preferably, it is 5 hours or less.

In the treatment such as immersion of the acidic compound in an aqueous solution, the pH is preferably adjusted to 6 or less.
By such neutralization, excellent heat aging resistance is obtained. The upper limit of the pH is more preferably 5 or less, still more preferably 4.5 or less. The lower limit is not particularly limited, and although it depends on the immersion time, it is preferably 1 or more, more preferably 2 or more, because if the acid is too strong, the rubber deteriorates or the wastewater treatment becomes troublesome. The immersion treatment can be performed by leaving the agglomerated rubber in an acidic compound aqueous solution.

After the treatment, the compound used for the treatment of the acidic compound may be removed, and then the agglomerated rubber after the treatment may be appropriately washed. Examples of the cleaning treatment include the same methods as described above. For example, the non-rubber component may be further reduced by repeating the cleaning and adjusted to a desired content. Further, the agglomerated rubber after the treatment with the acidic compound may be squeezed with a roll type squeezer or the like to form a sheet. By adding a step of squeezing the agglomerated rubber, the pH of the agglomerated rubber surface and inside can be made uniform, and a rubber having a desired performance can be obtained. If necessary, the modified natural rubber can be obtained by carrying out a washing and squeezing step, then cutting through a creper and drying. In addition, drying is not specifically limited, For example, it can implement using normal dryers, such as a trolley-type dryer used in order to dry TSR, a vacuum dryer, an air dryer, and a drum dryer.

[Production method 2]
(Step 2-1)
In step 2-1, the natural rubber latex is deproteinized. Thereby, a deproteinized natural rubber latex from which non-rubber components such as proteins are removed can be prepared. Examples of the natural rubber latex used in Step 2-1 include those described above.

As a method for deproteinization, a known method capable of removing a protein can be used without particular limitation, and examples thereof include a method of degrading a protein by adding a proteolytic enzyme to natural rubber latex.

The proteolytic enzyme used for the deproteinization treatment is not particularly limited, and any of those derived from bacteria, those derived from filamentous fungi, and those derived from yeast may be used. Specifically, protease, peptidase, cellulase, pectinase, lipase, esterase, amylase and the like can be used alone or in combination.

The amount of proteolytic enzyme added is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, still more preferably 0.05 parts by mass or more, with respect to 100 parts by mass of the solid content in the natural rubber latex. It is. If it is less than the lower limit, the protein degradation reaction may be insufficient.

In the deproteinization treatment, a surfactant may be added together with the proteolytic enzyme. Examples of the surfactant include anionic, cationic, nonionic, and amphoteric surfactants.

(Process 2-2)
In step 2-2, the deproteinized natural rubber latex obtained in step 2-1 is washed. By the washing, non-rubber components such as proteins are removed.

Step 2-2 can be performed, for example, by aggregating the deproteinized natural rubber latex obtained in Step 2-1 to produce an aggregated rubber, and then washing the obtained aggregated rubber. Thereby, non-rubber components such as protein strongly adhered to the agglomerated rubber can be removed.

The aggregation method can be carried out in the same manner as in Step 1-2. Furthermore, you may process with a basic compound as mentioned above as needed. After the production of the agglomerated rubber, a cleaning process is performed. The washing treatment can be carried out by the same method as in Step 1-2, whereby non-rubber components such as proteins and basic compounds can be removed. The cleaning treatment is preferably performed until the phosphorus content in the rubber is 200 ppm or less and / or the nitrogen content is 0.15 mass% or less for the same reason as described above.

(Step 2-3)
In step 2-3, the washed rubber obtained in step 2-2 is treated with an acidic compound. When the acid amount is small in acid aggregation as well as in the treatment with a basic compound, the heat aging resistance is reduced due to the fact that the finally obtained rubber becomes alkaline to neutral when extracted with water. Tend. In general, an enzyme having an optimum pH in the alkaline region is used as a proteolytic enzyme because it can be suitably deproteinized, and the enzyme reaction is performed under alkaline conditions in accordance with the optimum pH. In many cases, in order to adjust the final rubber pH to 2-7, the deproteinization treatment of natural rubber latex in step 2-1 is preferably carried out at pH 8-11, and pH 8.5-11 is preferred. More preferred. Thereafter, it is coagulated under acidity at the time of agglomeration, but if the rubber is washed only with water, the pH will be higher than that of the extract by the extraction described later, and in this case, particularly the heat aging resistance is greatly reduced. On the other hand, such a problem can be prevented and good heat aging resistance can be obtained by treatment with an acidic compound after solidification, if necessary, after solidification.

Examples of the acidic compound include the same ones as in Step 1-3. The method of treating the agglomerated rubber with an acid is not particularly limited as long as the agglomerated rubber is brought into contact with the acidic compound. For example, the method of immersing the agglomerated rubber in an aqueous solution of the acidic compound, Examples include a method of spraying an aqueous solution. An aqueous solution of an acidic compound can be prepared by diluting and dissolving each acidic compound with water.

The content of the acidic compound in 100% by mass of the aqueous solution is not particularly limited, but the lower limit is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and the upper limit is preferably 15% by mass or less. More preferably, it is 10 mass% or less, More preferably, it is 5 mass% or less. When the content is within the above range, good heat aging resistance can be obtained.

What is necessary is just to select the said process temperature and process time suitably, and should just employ | adopt the temperature similar to the said process 1-3. In the treatment such as immersion of the acidic compound in an aqueous solution, the pH is preferably adjusted to the same value as in Step 1-3.

After the treatment, the compound used for the treatment of the acidic compound may be removed, and then the agglomerated rubber after the treatment may be appropriately washed. Examples of the cleaning treatment include the same methods as described above. For example, the non-rubber component may be further reduced by repeating the cleaning and adjusted to a desired content. The modified natural rubber is obtained by drying after the washing treatment. In addition, drying is not specifically limited, The above-mentioned method etc. are employable.

Carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF. These carbon blacks may be used alone or in combination of two or more.

As white filler, those commonly used in the rubber industry, for example, mica such as silica, calcium carbonate, sericite, aluminum hydroxide, magnesium oxide, magnesium hydroxide, clay, talc, alumina, titanium oxide Etc. can be used. Among these, silica is particularly preferable from the viewpoint of low fuel consumption.

The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but wet process silica is preferable because of its large number of silanol groups.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ The rubber composition includes a silane coupling agent represented by the following formula (S1). By using the silane coupling agent represented by the formula (S1) and the modified natural rubber in combination, the performance balance of the various performances can be remarkably improved.

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

In the above formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ are each independently composed of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group having 1 to 18 carbon atoms. A group selected from the group is preferred. In addition, when R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is a group selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. Preferably there is. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ¹⁰⁰⁴ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene having 6 to 18 carbon atoms. And aralkylene groups having 7 to 18 carbon atoms. The alkylene group and alkenylene group may be linear or branched, and the cycloalkylene group, cycloalkylalkylene group, arylene group, and aralkylene group have a functional group such as a lower alkyl group on the ring. You may have. As R ¹⁰⁰⁴ , an alkylene group having 1 to 6 carbon atoms is preferable, and a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group is particularly preferable.

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ^{1008 in} the above formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec- Butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, Examples include cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
As examples of R ¹⁰⁰⁹ in the above formula (S1), examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group, and the like. , Isopropylene group, isobutylene group, 2-methylpropylene group and the like.

Specific examples of the silane coupling agent represented by the above formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3 -Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexa Noylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2 Octanoylthiopropyl ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane (NXT silane manufactured by Momentive Performance Materials) is particularly preferable in terms of both workability and low fuel consumption. The silane coupling agent may be used alone or in combination of two or more.

The content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass with respect to 100 parts by mass of the total content of carbon black and white filler. That's it. If it is less than 0.1 parts by mass, the rolling resistance tends to increase. Moreover, this content becomes like this. Preferably it is 20 mass parts or less, More preferably, it is 16 mass parts or less, More preferably, it is 12 mass parts or less. If it exceeds 20 parts by mass, the workability tends to be lowered.

Next, each member will be described.

<Under Tread>
In the rubber composition for undertread in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. It is. If it is less than 30% by mass, excellent fuel efficiency may not be obtained. Moreover, the upper limit of this content is not specifically limited, You may be 100 mass%.

Other rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber. (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. These may be used alone or in combination of two or more. Of these, NR, ENR, SBR, and BR are preferred because they do not deteriorate the properties of the rubber composition.

The content of the other rubber component in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 10% by mass from the viewpoint of exhibiting the minimum fuel economy, heat aging resistance and processability. It is as follows.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 30 m ² / g or more, more preferably 60 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. If it is less than 30 m ² / g, a sufficient reinforcing effect may not be obtained, and if it exceeds 300 m ² / g, fuel economy tends to be reduced.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

When carbon black is blended, the content of carbon black is preferably 1 part by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and still more preferably 80 parts by mass or less. If the amount is less than 1 part by mass, a sufficient reinforcing effect may not be obtained. If the amount exceeds 150 parts by mass, dispersibility and workability tend to deteriorate.

When the white filler is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 80 m ² / g or more. If it is less than 40 m < ² > / g, there exists a tendency for the fracture strength after vulcanization to fall. Further, nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 200 meters ² / g, more preferably 130m ² / g or less. When it exceeds 300 m ² / g, there is a tendency that low heat build-up and rubber processability are lowered. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

When silica is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

In the rubber composition for undertread in the present invention, the total content of carbon black and white filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably, with respect to 100 parts by mass of the rubber component. It is 20 parts by mass or more. The total content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel efficiency can be obtained.

The undertread rubber composition preferably contains oil or a plasticizer. Thereby, the hardness can be adjusted to an appropriate low level and good workability can be obtained. As the oil, for example, a paraffinic process oil, an aroma process oil, a naphthenic process oil, a low PCA process oil such as TDAE and MES, a vegetable oil or a mixture thereof can be used. It does not specifically limit as a plasticizer, A well-known thing can be used.

In addition to the above materials, the undertread rubber composition is generally used in the tire industry such as stearic acid, wax, resin, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators. Various materials may be appropriately blended.

In the present invention, the under tread is a member that is located between the tread rubber and the breaker (belt) rubber and covers the tire surface side portion of the breaker rubber, and specifically, JP 2009-191132 A. These are members shown in FIG.

<Sidewall>
In the rubber composition for a sidewall in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. It is. If it is less than 5% by mass, excellent fuel efficiency may not be obtained. Moreover, this content becomes like this. Preferably it is 80 mass% or less, More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less. If it exceeds 80% by mass, the flex crack growth resistance may be reduced.

Examples of rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like.

Especially, it is preferable to mix | blend BR from the point that favorable bending crack growth resistance is acquired. A compounded rubber in which a white filler such as silica is blended with BR generally has low dispersibility of the filler and it is difficult to obtain a desired performance. However, in the present invention, the blended rubber is filled by blending the modified natural rubber. The interaction between the agent and the rubber component is enhanced. Therefore, the dispersibility of the filler is improved, the fuel efficiency and the flex crack growth resistance are improved, and good processability is also obtained.

The BR is not particularly limited, and those that are common in the tire industry can be used.
The cis content of BR is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 97% by mass or more.

The molecular weight distribution (Mw / Mn) of BR is preferably 1.5 or more, more preferably 2.0 or more. If it is less than 1.5, workability may be deteriorated. The Mw / Mn of BR is preferably 5.0 or less, more preferably 4.0 or less. If it exceeds 5.0, the flex crack growth resistance tends to deteriorate. In the present invention, Mn and Mw are values converted from standard polystyrene using GPC.

The BR content in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass, from the viewpoint of exerting necessary fuel economy and bending crack growth resistance. % Or more. Further, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 70% by mass or less, from the viewpoint of workability.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 20 m ² / g or more, more preferably 30 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. When it is less than 20 m ² / g, they tend not sufficient reinforcing effect is obtained, and when it exceeds 300 meters ² / g, low fuel consumption property tends to be lowered.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

The content of carbon black is preferably 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel economy and flex crack growth resistance can be obtained.

The content of the white filler is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less. Within the above range, good fuel economy and flex crack growth resistance can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, and more preferably 50 m ² / g or more. If it is less than 40 m < ² > / g, there exists a tendency for the fracture strength after vulcanization to fall. The _N 2 SA of the silica is preferably 300 meters ² / g or less, more preferably 250m ² / g. When it exceeds 300 m ² / g, there is a tendency that low heat build-up and rubber processability are lowered. The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less. Within the above range, good fuel economy and flex crack growth resistance can be obtained.

In the rubber composition for a sidewall in the present invention, the total content of carbon black and white filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 100 parts by mass of the rubber component. It is 20 parts by mass or more. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel economy and flex crack growth resistance can be obtained.

The rubber composition preferably contains oil as a plasticizer. Thereby, the hardness can be adjusted to an appropriate low level and good workability can be obtained. The oil is not particularly limited, and conventionally known oils such as paraffinic process oils, aroma process oils, process oils such as naphthenic process oils, low PCA process oils such as TDAE and MES, vegetable fats and oils, and mixtures thereof. Can be used.

The oil content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 15 mass parts or less, More preferably, it is 10 mass parts or less. Within the above range, good processability is imparted, and excellent fuel economy and flex crack growth resistance are also obtained.

In addition to the above materials, the rubber composition for sidewalls in the present invention includes zinc oxide, stearic acid, various anti-aging agents, plasticizers other than oil (such as wax), and vulcanizing agents (sulfur, organic peroxides). Etc.) and various materials generally used in the tire industry such as vulcanization accelerators (sulfenamide-based, guanidine-based vulcanization accelerators, etc.) may be appropriately blended.

<Wing>
In the rubber composition for a wing in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more. . If it is less than 5% by mass, excellent fuel efficiency may not be obtained. Moreover, this content becomes like this. Preferably it is 80 mass% or less, More preferably, it is 70 mass% or less, More preferably, it is 60 mass% or less. If it exceeds 80% by mass, the rubber strength may decrease.

Examples of rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. Among these, NR, ENR, SBR, and BR are preferable because they do not deteriorate the characteristics of the rubber composition for wing in the present invention. These may be used alone or in combination of two or more.

Especially, it is preferable to mix | blend BR from the point that the outstanding rubber | gum strength is acquired. A compounded rubber in which a white filler such as silica is blended with BR generally has low dispersibility of the filler and it is difficult to obtain a desired performance. However, in the present invention, the blended rubber is filled by blending the modified natural rubber. The interaction between the agent and the rubber component is enhanced. Accordingly, the dispersibility of the filler is improved, fuel efficiency and rubber strength are improved, and good processability is also obtained.

The BR is not particularly limited, and those that are common in the tire industry can be used.
The cis content of BR is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 97% by mass or more.

The molecular weight distribution (Mw / Mn) of BR is preferably 1.5 or more, more preferably 2.0 or more. If it is less than 1.5, workability may be deteriorated. The Mw / Mn of BR is preferably 5.0 or less, more preferably 4.0 or less. If it exceeds 5.0, the flex crack growth resistance tends to deteriorate. In the present invention, Mn and Mw are values converted from standard polystyrene using GPC.

The content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more, from the viewpoint of exerting necessary low fuel consumption and rubber strength. is there. The content is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less from the viewpoint of workability.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 30 m ² / g or more, more preferably 60 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. When it is less than 30 m ² / g, there is a tendency that a sufficient reinforcing effect cannot be obtained, and when it exceeds 300 m ² / g, there is a tendency that fuel efficiency is lowered.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

The content of carbon black is preferably 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and still more preferably 50 parts by mass or less. Within the above range, good fuel economy and rubber strength can be obtained.

The content of the white filler is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less, More preferably, it is 80 mass parts or less. When the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient, causing a problem in terms of durability, and when it exceeds 120 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 80 m ² / g or more. If it is less than 40 m < ² > / g, there exists a tendency for the fracture strength after vulcanization to fall. Further, N ₂ SA of silica is preferably 300 m ² / g or less, more preferably 200 m ² / g or less, and further preferably 130 m ² / g. When it exceeds 300 m ² / g, there is a tendency that low heat build-up and rubber processability are lowered. The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less, More preferably, it is 80 mass parts or less. When the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient, causing a problem in terms of durability, and when it exceeds 120 parts by mass, the workability tends to deteriorate.

In the rubber composition for a wing in the present invention, the total content of carbon black and white filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 20 parts per 100 parts by mass of the rubber component. More than part by mass. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel economy and rubber strength can be obtained.

The rubber composition for wing preferably contains oil or a plasticizer. Thereby, the hardness can be adjusted to an appropriate low level and good workability can be obtained. As the oil, for example, a paraffinic process oil, an aroma process oil, a naphthenic process oil, a low PCA process oil such as TDAE and MES, a vegetable oil or a mixture thereof can be used. It does not specifically limit as a plasticizer, A well-known thing can be used.

In addition to the above materials, the rubber composition for wing in the present invention is generally used in the tire industry such as stearic acid, wax, resin, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators. The various materials currently used may be mix | blended suitably.

In the present invention, the wing is a member located between the tread and the sidewall in the shoulder portion, and specifically, the member shown in FIGS. 1 and 3 of JP-A-2007-176267.

<Prightening>
In the rubber composition for pleating in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. Especially preferably, it is 50 mass% or more. If the content is less than 5% by mass, excellent fuel economy, adhesive strength and breaking strength may not be obtained. Moreover, although the upper limit of this content is not specifically limited, Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less.

The pretapping rubber composition in the present invention preferably contains styrene butadiene rubber (SBR) as a rubber component.

Although it does not specifically limit as styrene butadiene rubber (SBR) used in this invention, Solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), these modified SBR, etc. are mentioned. Examples of the modified SBR include SBR having a terminal and / or main chain modified, modified SBR coupled with tin, a silicon compound, or the like (condensate, one having a branched structure, or the like).

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more. If it is less than 5% by mass, sufficient grip performance and rubber strength may not be obtained. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 30% by mass or less. If it exceeds 60% by mass, there is a possibility that excellent fuel efficiency cannot be obtained. In the present specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The vinyl content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more. If it is less than 10% by mass, sufficient grip performance and rubber strength may not be obtained. The vinyl content is preferably 65% by mass or less, more preferably 60% by mass or less, and still more preferably 45% by mass or less. If it exceeds 65% by mass, excellent fuel efficiency may not be obtained. In the present specification, the vinyl content of the SBR indicated that the amount of vinyl butadiene part, is calculated by H ¹ -NMR measurement.

The content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more. If it is less than 5% by mass, the reversion resistance may decrease. The content of the SBR is preferably 60% by mass or less, more preferably 50% by mass or less. When it exceeds 60% by mass, there is a possibility that excellent low fuel consumption performance due to the modified natural rubber cannot be obtained.

Examples of rubber components other than the modified natural rubber and SBR include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene isoprene butadiene. Examples thereof include rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 20 m ² / g or more, more preferably 30 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 200 m ² / g or less, still more preferably 100 m ² / g or less, and particularly preferably 50 m ² / g or less. If it is less than 20 m ² / g, there is a tendency that a sufficient reinforcing effect cannot be obtained, and if it exceeds 300 m ² / g, the viscosity at the time of unvulcanization becomes very high, the workability deteriorates, and the fuel efficiency is low. There is a tendency to deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

The content of carbon black is preferably 10 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less. When the amount is less than 10 parts by mass, sufficient reinforcing properties tend not to be obtained. When the amount exceeds 100 parts by mass, heat generation increases and fuel efficiency tends to deteriorate.

In the rubber composition for pleating in the present invention, the total content of carbon black and white filler is preferably 10 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel economy, adhesive strength and breaking strength can be obtained.

The rubber composition for pleating in the present invention preferably contains zinc oxide. By blending zinc oxide, the adhesion between the cord and the rubber is improved. It also serves as a rubber vulcanization aid. There is also an effect of suppressing scorch.

The content of zinc oxide is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and further preferably 4 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, the adhesion between the steel cord plating layer and the rubber may be insufficient, or the rubber may be insufficiently vulcanized. The content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less. When it exceeds 25 mass parts, there exists a possibility that breaking strength may fall.

In the rubber composition for pleating in the present invention, sulfur can be suitably used as a vulcanizing agent. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

The sulfur content is preferably 2 parts by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, a sufficient crosslinking density cannot be obtained, and the adhesion performance may be deteriorated. Moreover, this content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 8 mass parts or less, More preferably, it is 6 mass parts or less. If it exceeds 10 parts by mass, the heat-resistant deterioration property may be deteriorated.

In addition to the above-mentioned materials, the pretapping rubber composition according to the present invention includes various types commonly used in the tire industry such as plasticizers such as oil, stearic acid, various anti-aging agents, and vulcanization accelerators. Materials may be blended as appropriate.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization. Accelerators are mentioned. Of these, sulfenamide-based vulcanization accelerators are preferred because of their excellent scorch properties.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N And '-dicyclohexyl-2-benzothiazolylsulfenamide (DZ).

As the oil, for example, process oil, vegetable oil and fat, a mixture thereof and the like can be used. Process oils include paraffinic process oils, naphthenic process oils, aromatic process oils, low PCA process oils such as TDAE and MES.

The oil content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 8 mass parts or less, More preferably, it is 6 mass parts or less. If it is out of the above range, there is a possibility that wet heat resistance and durability cannot be improved sufficiently.

As a method for producing the rubber composition of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneader such as an open roll or a Banbury mixer, and then vulcanized. Can be manufactured.

The rubber composition for pre-tapping in the present invention can be suitably used as a rubber composition for pre-topping that covers a cord in a carcass ply or a belt ply.

A pneumatic tire having a pre-tapping produced using the rubber composition is produced by a usual method using the rubber composition. That is, the rubber composition is kneaded using a normal method, and the resulting unvulcanized rubber composition is pressure-bonded to a cord to form an unvulcanized belt-like ply (rubber pressure-bonding cord). The ply is pasted together with other members on a tire molding machine by an ordinary method to form an unvulcanized tire. This unvulcanized tire can be heated and pressurized in a vulcanizer to obtain a pneumatic tire.

<Break topping>
In the rubber composition for breaker topping in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. The upper limit is not particularly limited and may be 100% by mass, particularly preferably 50% by mass or more, and most preferably 80% by mass or more. If the amount is less than 5% by mass, excellent fuel economy and breaking strength may not be obtained.

Examples of rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. Among these, NR is preferable because good fracture characteristics (breaking strength) can be obtained. As NR, those generally used in the tire industry such as SIR20, RSS # 3, TSR20 and the like can be used. Among them, it is particularly preferable to use RSS # 3 from the viewpoint of rubber strength.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 20 m ² / g or more, more preferably 30 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 200 m ² / g or less, still more preferably 100 m ² / g or less, particularly preferably 70 m ² / g or less, and most preferably 50 m ² / g or less. It is. If it is less than 20 m ² / g, there is a tendency that a sufficient reinforcing effect cannot be obtained, and if it exceeds 300 m ² / g, the viscosity at the time of unvulcanization becomes very high, the workability deteriorates, and the fuel efficiency is low. There is a tendency to deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

The content of carbon black is preferably 5 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less. When the amount is less than 5 parts by mass, sufficient reinforcing properties tend not to be obtained. When the amount exceeds 100 parts by mass, heat generation increases and fuel economy tends to deteriorate.

The rubber composition for breaker topping in the present invention preferably contains an organic acid cobalt. Since the organic acid cobalt plays a role of cross-linking the cord (steel cord) and the rubber, the adhesion between the cord and the rubber can be improved by blending this component.

Examples of the organic acid cobalt include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and boron 3 neodecanoate cobalt. Of these, cobalt stearate and cobalt naphthenate are preferable.

The content of the organic acid cobalt is preferably 0.05 parts by mass or more, more preferably 0.08 parts by mass or more in terms of the amount of cobalt metal with respect to 100 parts by mass of the rubber component. If it is less than 0.05 parts by mass, the adhesion between the steel cord plating layer and the rubber may be insufficient. Moreover, this content becomes like this. Preferably it is 0.5 mass part or less, More preferably, it is 0.3 mass part or less, More preferably, it is 0.2 mass part or less. If the amount exceeds 0.5 parts by mass, the oxidative degradation of the rubber becomes significant, and the fracture characteristics tend to deteriorate.

The rubber composition for breaker topping in the present invention preferably contains zinc oxide. By blending zinc oxide, the adhesion between the steel cord plating layer and the rubber is improved. It also serves as a rubber vulcanization aid. There is also an effect of suppressing scorch.

The content of zinc oxide is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 6 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, the adhesion between the steel cord plating layer and the rubber may be insufficient, or the rubber may be insufficiently vulcanized. The content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less. If it exceeds 25 parts by mass, the rubber strength may be reduced.

In the rubber composition for breaker topping in the present invention, sulfur can be suitably used as a vulcanizing agent. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

The sulfur content is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and still more preferably 4 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 2 parts by mass, a sufficient crosslinking density cannot be obtained, and the adhesion performance may be deteriorated. Moreover, this content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 8 mass parts or less, More preferably, it is 6 mass parts or less. If it exceeds 10 parts by mass, the heat aging resistance may deteriorate.

In addition to the above materials, the rubber composition for breaker topping in the present invention includes various kinds of plasticizers such as oil, stearic acid, various anti-aging agents, and vulcanization accelerators that are generally used in the tire industry. Materials may be blended as appropriate.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization. Accelerators are mentioned. Of these, sulfenamide-based vulcanization accelerators are preferred because of their excellent scorch properties.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N And '-dicyclohexyl-2-benzothiazolylsulfenamide (DZ).

Examples of the anti-aging agent include amine / ketones, amines, phenols, imidazoles, and thioureas. These anti-aging agents may be used alone or in combination of two or more. Among them, amine-based anti-aging agents may be used because of their excellent fracture characteristics and heat resistance. preferable.

Examples of amine-based antioxidants include diphenylamine-based and p-phenylenediamine-based amine derivatives. Examples of the diphenylamine derivative include p- (p-toluenesulfonylamide) -diphenylamine, octylated diphenylamine, and the like. Examples of p-phenylenediamine derivatives include N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), N-phenyl-N′-isopropyl-p-phenylenediamine (IPPD). ), N, N′-di-2-naphthyl-p-phenylenediamine, and the like.

The content of the anti-aging agent is preferably 1 part by mass or more, more preferably 1.3 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 1 part by mass, the fracture characteristics may not be improved. Moreover, this content becomes like this. Preferably it is 6 mass parts or less, More preferably, it is 4 mass parts or less, More preferably, it is 2 mass parts or less. When the amount exceeds 6 parts by mass, the anti-aging agent may be deposited on the surface and the rubber physical properties may be deteriorated. Since the rubber composition for breaker topping in the present invention is excellent in heat aging resistance, it can have sufficient durability even when the anti-aging agent is 2 parts by mass or less.

As the oil, for example, process oil, vegetable oil and fat, a mixture thereof and the like can be used. Process oils include paraffinic process oils, naphthenic process oils, aromatic process oils, low PCA process oils such as TDAE and MES.

The oil content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 8 mass parts or less, More preferably, it is 6 mass parts or less. If it is out of the above range, there is a possibility that wet heat resistance and durability cannot be improved sufficiently.

The rubber composition for breaker topping in the present invention can be used as a rubber composition for steel cords. Examples of the steel cord include a single-stranded steel cord having a 1 × n configuration, a layer-twisted steel cord having a k + m configuration, and the like (n is an integer of 1 to 27, k is an integer of 1 to 10, and m is an integer of 1 to 3). Such).

The rubber composition for breaker topping in the present invention is used for a breaker disposed inside the tread and radially outside the carcass. Specifically, it is used for the breaker shown in FIG. 3 of JP-A-2003-94918, FIG. 1 of JP-A-2004-67027, and FIGS. 1-4 of JP-A-4-356205.

A pneumatic tire having breaker topping produced using the rubber composition for breaker topping is manufactured by a usual method using the rubber composition. That is, a steel cord is coated with the above rubber composition and formed into a breaker shape, and then bonded to another tire member to form an unvulcanized tire and vulcanize to form a pneumatic tire (radial tire or the like). Can be manufactured.

<Clinch Apex>
In the rubber composition for clinch apex in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 30% by mass. That's it. If the amount is less than 5% by mass, excellent fuel economy and breaking strength may not be obtained. Moreover, although the upper limit of this content is not specifically limited, Preferably it is 90 mass% or less, More preferably, it is 70 mass% or less.

Examples of rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. These may be used alone or in combination of two or more. Among these, BR is particularly preferable from the viewpoint of breaking strength and low fuel consumption.

It is not particularly limited as BR, for example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having high cis content such as BR150B, VCR412 manufactured by Ube Industries, Ltd., VCR617, etc. BR containing syndiotactic polybutadiene crystals can be used. From the viewpoint of improving the mechanical strength, the cis content of BR is preferably 95% by mass or more.

The vinyl content (1,2-bonded butadiene unit amount) of BR is preferably 35% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, and particularly preferably 10% by mass or less. If it exceeds 35% by mass, the low heat build-up tends to be impaired. The lower limit of the content is not particularly limited. In the present specification, the vinyl content of BR can be measured by infrared absorption spectrum analysis.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 30% by mass or more. The BR content is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less. If it is less than 5% by mass, the breaking strength may be deteriorated, and if it exceeds 80% by mass, the workability tends to be deteriorated.

The total content of the modified natural rubber and BR in 100% by mass of the rubber component is preferably 80% by mass or more, and more preferably 100% by mass. When the content is within the above range, excellent fuel economy and processability can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 10 m ² / g or more, more preferably 30 m ² / g or more, and still more preferably 50 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. If it is less than 10 m ² / g, sufficient breaking strength may not be obtained. If it exceeds 300 m ² / g, the viscosity at the time of unvulcanization becomes very high, workability deteriorates, and fuel consumption is low. There is a tendency to deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

The content of carbon black is preferably 3 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and still more preferably 30 parts by mass or less. If the amount is less than 3 parts by mass, sufficient breaking strength may not be obtained. If the amount exceeds 100 parts by mass, dispersibility and workability tend to deteriorate.

When the white filler is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 70 mass parts or less, More preferably, it is 50 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 100 m ² / g or more, and more preferably 110 m ² / g or more. If it is less than 100 m ² / g, the reinforcing effect tends to be insufficient. Further, nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 280 meters ² / g or less, 200 meters ² / g or less is more preferable. If it exceeds 300 m ² / g, the dispersibility of the silica tends to decrease and the heat generation tends to increase. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 70 mass parts or less, More preferably, it is 50 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

In the rubber composition for clinch apex in the present invention, the total content of carbon black and white filler is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, further preferably 100 parts by mass of the rubber component. Is 40 parts by mass or more. The total content is preferably 100 parts by mass or less, and more preferably 80 parts by mass or less. The effect of this invention can fully be exhibited as it exists in the said range.

The rubber composition for clinch apex in the present invention includes tires such as plasticizers such as oil and wax, stearic acid, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators in addition to the above materials. Various materials generally used in industry may be appropriately blended.

The clinch apex is a rubber portion disposed on the inner end of the sidewall. Specifically, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 2008-75066, FIG. 1 of Japanese Patent Application Laid-Open No. 2004-106796, and the like. It is a member shown by these.

<Bead Apex>
In the rubber composition for bead apex in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 30% by mass. As described above, it is particularly preferably 50% by mass or more. If it is less than 5% by mass, excellent fuel economy and rubber strength may not be obtained. Moreover, although the upper limit of this content is not specifically limited, Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less.

Examples of rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. These may be used alone or in combination of two or more. Among these, SBR is particularly preferable because it is advantageous in terms of cost and ensures adhesion performance with an adjacent member.

Although it does not specifically limit as SBR, Solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), etc. can be used.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more. If it is less than 5% by mass, sufficient rubber strength may not be obtained. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 45% by mass or less. If it exceeds 60% by mass, there is a possibility that excellent fuel efficiency cannot be obtained. In the present specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The Mooney viscosity ML (1 + 4) 100 ° C. of SBR is preferably 35 or higher, more preferably 45 or higher, and still more preferably 50 or higher. If it is less than 35, the viscosity of the unvulcanized rubber composition is low, and there is a possibility that an appropriate thickness cannot be ensured after vulcanization. The Mooney viscosity is preferably 65 or less, more preferably 60 or less. If it exceeds 65, the unvulcanized rubber composition becomes too hard and it may be difficult to extrude with a smooth edge. The Mooney viscosity of SBR is measured according to ISO289 and JIS K6300.

The content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. The SBR content is preferably 95% by mass or less, more preferably 60% by mass or less, still more preferably 55% by mass or less, and particularly preferably 50% by mass or less. When the SBR content is within the above range, good fuel economy and processability can be obtained.

The total content of the modified natural rubber and SBR in 100% by mass of the rubber component is preferably 80% by mass or more, and more preferably 100% by mass. When the content is within the above range, excellent fuel economy, processability, and cost merit can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 10 m ² / g or more, more preferably 30 m ² / g or more, and still more preferably 50 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. If it is less than 10 m ² / g, sufficient adhesion and rubber strength may not be obtained. If it exceeds 300 m ² / g, the unvulcanized viscosity becomes very high, and the workability deteriorates. In addition, fuel efficiency tends to deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

When carbon black is blended, the carbon black content is preferably 3 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less. If the amount is less than 3 parts by mass, sufficient adhesiveness and rubber strength may not be obtained. If the amount exceeds 100 parts by mass, dispersibility and workability tend to deteriorate.

When the white filler is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 35 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 65 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 100 m ² / g or more, and more preferably 110 m ² / g or more. If it is less than 100 m ² / g, the reinforcing effect tends to be insufficient. Further, nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 280 meters ² / g or less, 200 meters ² / g or less is more preferable. If it exceeds 300 m ² / g, the dispersibility of the silica tends to decrease and the heat generation tends to increase. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

When silica is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 35 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 65 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

In the rubber composition for bead apex in the present invention, the total content of carbon black and white filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 100 parts by mass of the rubber component. Is 20 parts by mass or more. The total content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel efficiency and breaking strength can be obtained.

The rubber composition for bead apex in the present invention preferably contains zinc oxide. By blending zinc oxide, the effect of suppressing reversion and promoting vulcanization can be obtained.

The content of zinc oxide is preferably 2 parts by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 15 mass parts or less, More preferably, it is 10 mass parts or less. If it is less than 2 parts by mass, the effect as a vulcanization accelerator may be difficult to obtain, and if it exceeds 15 parts by mass, the rubber strength may be reduced.

The rubber composition for bead apex in the present invention includes tires such as plasticizers such as resins and oils, stearic acid, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators in addition to the above materials. Various materials generally used in industry may be appropriately blended.

Examples of the resin include phenol resins and cresol resins, and among them, phenol resins are preferable. As phenolic resins, phenol resins obtained by reacting phenols with aldehydes such as formaldehyde, acetaldehyde, furfural; cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins , Modified phenolic resins modified with aniline, melamine and the like. Of these, a modified phenolic resin is preferable and a cashew oil-modified phenolic resin is particularly preferable from the viewpoint of improving hardness.

When blending the resin, the content of the resin is preferably 1 part by mass or more and more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint that sufficient hardness is obtained. The content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, from the viewpoint of excellent workability.

The rubber composition for a bead apex in the present invention is used for a bead apex arranged inside a tire clinch so as to extend radially outward from the bead core. Specifically, it is used for the members shown in FIGS. 1 to 3 of JP-A-2008-38140, FIG. 1 of JP-A-2004-339287, and the like.

<Sidewall reinforcement layer>
In the rubber composition for a sidewall reinforcing layer in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass. % Or more. If it is less than 30% by mass, excellent fuel efficiency may not be obtained. Moreover, the upper limit of this content is not specifically limited, You may be 100 mass%.

Other rubber components that can be used in addition to the modified natural rubber include natural rubber (non-modified) (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber. (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. These may be used alone or in combination of two or more. Of these, NR, ENR, SBR, and BR are preferred because they do not deteriorate the properties of the rubber composition.

The content of the other rubber component in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 10% by mass from the viewpoint of exhibiting the minimum fuel economy, heat aging resistance and processability. It is as follows.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² / g or more, more preferably 80 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, and still more preferably 200 m ² / g or less. If it is less than 50 m ² / g, a sufficient reinforcing effect may not be obtained, and if it exceeds 300 m ² / g, fuel economy tends to decrease.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

When carbon black is blended, the content of carbon black is preferably 3 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and still more preferably 80 parts by mass or less. If the amount is less than 3 parts by mass, a sufficient reinforcing effect may not be obtained. If the amount exceeds 150 parts by mass, dispersibility and workability tend to deteriorate.

When the white filler is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 80 m ² / g or more. If it is less than 40 m < ² > / g, there exists a tendency for the fracture strength after vulcanization to fall. Further, nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 200 meters ² / g, more preferably 130m ² / g or less. When it exceeds 300 m ² / g, there is a tendency that low heat build-up and rubber processability are lowered. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

When silica is blended, the content thereof is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

In the rubber composition for a sidewall reinforcing layer in the present invention, the total content of carbon black and white filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, with respect to 100 parts by mass of the rubber component. Preferably it is 20 mass parts or more. The total content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. Within the above range, good fuel efficiency can be obtained.

The rubber composition for a sidewall reinforcing layer preferably contains oil or a plasticizer. Thereby, the hardness can be adjusted to an appropriate low level and good workability can be obtained. As the oil, for example, a paraffinic process oil, an aroma process oil, a naphthenic process oil, a low PCA process oil such as TDAE and MES, a vegetable oil or a mixture thereof can be used. It does not specifically limit as a plasticizer, A well-known thing can be used.

In addition to the above materials, the rubber composition for a sidewall reinforcing layer in the present invention is generally used in the tire industry such as stearic acid, wax, resin, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators. Various materials that are commonly used may be appropriately blended.

The rubber composition for a sidewall reinforcing layer in the present invention can be suitably used for a sidewall reinforcing layer of a run flat tire, for example. The side wall reinforcing layer refers to a lining strip layer disposed inside the side wall portion. Specifically, the side wall reinforcing layer is disposed from the bead portion to the shoulder portion in contact with the inner side of the carcass ply and has a thickness in both end directions. A crescent-shaped reinforcing rubber layer that gradually decreases, a reinforcing rubber layer disposed between the bead portion and the tread portion between the carcass ply main body portion and the folded portion, and two layers disposed between the plurality of carcass plies or the reinforcing plies. Examples thereof include a reinforced rubber layer. Specifically, it is used for the members shown in FIG. 1 of JP-A-2007-326559, FIG. 1 of JP-A-2004-330822, and the like.

<Inner liner>
In the rubber composition for an inner liner in the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. It is. If the amount is less than 5% by mass, excellent fuel economy and breaking strength may not be obtained. The upper limit of the content is not particularly limited, but is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less.

The rubber composition for an inner liner in the present invention preferably contains epoxidized natural rubber (ENR) from the viewpoint of low fuel consumption and resource protection.

As ENR, a commercially available product may be used, or an NR epoxidized product may be used. The method for epoxidizing NR is not particularly limited, and examples thereof include a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, and a peracid method. Examples of the peracid method include a method of reacting an organic peracid such as peracetic acid or performic acid as an epoxidizing agent with an emulsion of natural rubber.

The epoxidation rate of ENR is preferably 1 to 85 mol%. If the epoxidation rate is less than 1 mol%, the modification effect of the rubber composition tends to be small. Moreover, when the epoxidation rate exceeds 85 mol%, the polymer in the rubber composition tends to gel.
Here, the epoxidation rate means the ratio of the number of epoxidized out of the total number of carbon-carbon double bonds in the natural rubber before epoxidation, for example, by titration analysis or nuclear magnetic resonance (NMR) analysis. Desired.

When ENR is blended, the ENR content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more. Moreover, this content becomes like this. Preferably it is 99 mass% or less, More preferably, it is 90 mass% or less, More preferably, it is 70 mass% or less. If it is less than 10% by mass, the effect of dispersing the filler in the rubber composition tends to be small, and if it exceeds 99% by mass, good processability and breaking strength may not be obtained.

Examples of rubber components that can be used in addition to the modified natural rubber, the butyl rubber, and the ENR include natural rubber (non-modified) (NR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, and further preferably 23 m ² / g or more. The N ₂ SA is preferably 300 m ² / g or less, more preferably 250 m ² / g or less, still more preferably 100 m ² / g or less, and particularly preferably 50 m ² / g or less. If it is less than 10 m ² / g, sufficient adhesion and rubber strength may not be obtained. If it exceeds 300 m ² / g, the unvulcanized viscosity becomes very high, and the workability deteriorates. In addition, fuel efficiency tends to deteriorate.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

When carbon black is blended, the carbon black content is preferably 3 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 60 parts by mass or less. If the amount is less than 3 parts by mass, sufficient wear resistance, adhesiveness and rubber strength may not be obtained. If the amount exceeds 100 parts by mass, dispersibility and workability tend to deteriorate.

When the white filler is blended, the content thereof is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² / g or more, and more preferably 70 m ² / g or more. If it is less than 50 m ² / g, the reinforcing effect tends to be insufficient. Further, nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 280 meters ² / g or less, 200 meters ² / g or less is more preferable. If it exceeds 300 m ² / g, the dispersibility of the silica tends to decrease and the heat generation tends to increase. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

When silica is blended, the content of silica is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 5 parts by mass, the reinforcing property of the rubber is insufficient and a problem occurs in terms of durability. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 60 mass parts or less. When it exceeds 100 parts by mass, the workability tends to deteriorate.

In addition to the above materials, the rubber composition for the inner liner in the present invention includes tire industry such as plasticizers such as oil and wax, stearic acid, various anti-aging agents, vulcanizing agents such as sulfur, and vulcanization accelerators. Various materials generally used in the above may be appropriately blended.

The rubber composition for an inner liner in the present invention is used for an inner liner formed so as to form a tire lumen surface, and this member can reduce the air permeation amount and maintain the tire internal pressure. it can. Specifically, it is used for the members shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2008-291091, FIGS. 1-2 of Japanese Patent Application Laid-Open No. 2007-160980, and the like.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition for each member. That is, the rubber composition is extruded in accordance with the shape of each member at an unvulcanized stage, molded by a normal method on a tire molding machine, and bonded together with other tire members to form an unvulcanized tire. Form. The unvulcanized tire can be heated and pressurized in a vulcanizer to obtain the pneumatic tire of the present invention.

The pneumatic tire of the present invention is preferably used as a tire for passenger cars, a tire for trucks and buses, a tire for motorcycles, a tire for competition, and the like, and particularly preferably used as a tire for passenger cars.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
Below, the various chemical | medical agents used by the manufacture example and the comparative manufacture example are demonstrated.
Field Latex: Field Latex Emar E-27C (surfactant) obtained from Muhiba Latex Co., Ltd .: Emar E-27C (Polyoxyethylene lauryl ether sodium sulfate, 27% by mass of active ingredient) manufactured by Kao Corporation
NaOH: NaOH manufactured by Wako Pure Chemical Industries, Ltd.
Wingstay L (anti-aging agent): WINGSTAY L (compound obtained by butylating the condensate of ρ-cresol and dicyclopentadiene) manufactured by ELIOKEM
Emulvin W (surfactant): Emalvin W (aromatic polyglycol ether) manufactured by LANXESS
Tamol NN9104 (surfactant): Tamol NN9104 manufactured by BASF (Naphthalenesulfonic acid / formaldehyde sodium salt)
Van gel B (surfactant): Van gel B (magnesium aluminum silicate hydrate) manufactured by Vanderbilt
NR: TSR20

(Preparation of anti-aging agent dispersion)
462.5 g of water was mixed with 12.5 g of Emulvin W, 12.5 g of Tamol NN9104, 12.5 g of Van gel B, and 500 g of Wingstay L (total of 1000 g) for 16 hours by a ball mill to prepare an antioxidant dispersion.

(Production Example 1)
After adjusting the solid content concentration (DRC) of the field latex to 30% (w / v), 25 g of 10% Emar E-27C aqueous solution and 60 g of 25% NaOH aqueous solution were added to 1000 g of the latex and saponified for 24 hours at room temperature. Reaction was performed to obtain a saponified natural rubber latex. Next, 6 g of the anti-aging dispersion was added and stirred for 2 hours, and then further diluted with water to a rubber concentration of 15% (w / v). Next, formic acid was added with slow stirring to adjust the pH to 4.0, and then a cationic polymer flocculant was added and stirred for 2 minutes for aggregation. The diameter of the aggregate (aggregated rubber) obtained in this way was about 0.5 to 3 mm. The obtained agglomerates were taken out and immersed in 1000 ml of a 2% by weight aqueous sodium carbonate solution at room temperature for 4 hours, and then the rubber was taken out. To this, 2000 ml of water was added and stirred for 2 minutes to remove water as much as possible 7 times. Thereafter, 500 ml of water was added, 2% by mass formic acid was added until pH 4 was reached, and the mixture was allowed to stand for 15 minutes. Further, after removing the water as much as possible, repeating the work of adding water again and stirring for 2 minutes three times, squeezing the water with a water squeezing roll to form a sheet, and then drying at 90 ° C. for 4 hours to solid rubber ( A high-purity natural rubber A) was obtained.

(Production Example 2)
A solid rubber (high-purity natural rubber B) was obtained in the same procedure except that 2% by mass of formic acid was added until pH 1 in Production Example 1.

(Comparative Production Example 1)
After adjusting the solid content concentration (DRC) of the field latex to 30% (w / v), 25 g of 10% Emar E-27C aqueous solution and 60 g of 25% NaOH aqueous solution were added to 1000 g of the latex and saponified for 24 hours at room temperature. Reaction was performed to obtain a saponified natural rubber latex. Next, 6 g of the anti-aging dispersion was added and stirred for 2 hours, and then further diluted with water to a rubber concentration of 15% (w / v). Next, formic acid was added with slow stirring to adjust the pH to 4.0, and then a cationic polymer flocculant was added and stirred for 2 minutes for aggregation. The diameter of the aggregate (aggregated rubber) thus obtained was about 3 to 12 mm. The obtained agglomerates were taken out and immersed in 1000 ml of a 2% by weight aqueous sodium carbonate solution at room temperature for 4 hours, and then the rubber was taken out. To this, 1000 ml of water was added and stirred for 2 minutes to remove water as much as possible, and then dried at 90 ° C. for 4 hours to obtain a solid rubber (high purity natural rubber C).

(Comparative Production Example 2)
The same procedure was followed, except that it was treated with an aqueous sodium carbonate solution in Production Example 1 and washed with water seven times, and then the sheet was formed by squeezing water with a water squeezing roll without acid treatment with 2% by mass formic acid. A solid rubber (high purity natural rubber D) was obtained.

(Production Example 3)
Commercially available high-ammonia latex (manufactured by Mujiba Latex of Malaysia, solid rubber content 62.0%) is diluted with 0.12% sodium naphthenate aqueous solution to make the solid rubber content 10%, and dihydrogen phosphate. Sodium was added to adjust the pH to 9.2. And with respect to 10g of rubber | gum, after adding proteolytic enzyme (Alcalase 2.0M) in the ratio of 0.87g and adjusting pH again to 9.2, it maintained at 37 degreeC for 24 hours.
Next, a 1% aqueous solution of a nonionic surfactant (trade name Emulgen 810 manufactured by Kao Corporation) was added to the latex that had been subjected to the enzyme treatment to adjust the rubber concentration to 8%, and 11,000 r. p. m. The solution was centrifuged at a rotation speed of 30 minutes. Next, the cream-like fraction produced by centrifugation was dispersed in a 1% aqueous solution of Emulgen 810 to adjust the rubber concentration to 8%. p. m. The solution was centrifuged at a rotation speed of 30 minutes. After repeating this operation twice, the obtained creamy fraction was dispersed in distilled water to prepare a deproteinized rubber latex having a solid rubber content of 60%.
To this latex, 2% by mass formic acid was added until the pH reached 4, and a cationic polymer flocculant was further added to obtain 0.5 to 3 mm rubber particles. The water was removed as much as possible, 50 g of water was added to 10 g of rubber, and 2% by mass formic acid was added until pH 3 was reached. After 30 minutes, the rubber was pulled up, formed into a sheet with a creper, and dried at 90 ° C. for 4 hours to obtain a solid rubber (high-purity natural rubber E).

(Production Example 4)
A solid rubber (high-purity natural rubber F) was obtained in the same procedure except that 2% by mass formic acid was added until pH 1 in Production Example 3.

(Comparative Production Example 3)
Commercially available high-ammonia latex (manufactured by Mujiba Latex of Malaysia, solid rubber content 62.0%) is diluted with 0.12% sodium naphthenate aqueous solution to make the solid rubber content 10%, and dihydrogen phosphate. Sodium was added to adjust the pH to 9.2. And with respect to 10g of rubber | gum, after adding proteolytic enzyme (Alcalase 2.0M) in the ratio of 0.87g and adjusting pH again to 9.2, it maintained at 37 degreeC for 24 hours.
Next, a 1% aqueous solution of a nonionic surfactant (trade name Emulgen 810 manufactured by Kao Corporation) was added to the latex that had been subjected to the enzyme treatment to adjust the rubber concentration to 8%, and 11,000 r. p. m. The solution was centrifuged at a rotation speed of 30 minutes. Next, the cream-like fraction produced by centrifugation was dispersed in a 1% aqueous solution of Emulgen 810 to adjust the rubber concentration to 8%. p. m. The solution was centrifuged at a rotation speed of 30 minutes. After repeating this operation once more, the resulting creamy fraction was dispersed in distilled water to prepare a deproteinized rubber latex having a solid rubber content of 60%.
50% by mass formic acid was added to the latex until the rubber solidified, and the solidified rubber was taken out. The rubber was formed into a sheet while being washed with water with a creper, and then dried at 90 ° C. for 4 hours to obtain a solid rubber (high-purity natural rubber G).

(Comparative Production Example 4)
The rubber solidified in Comparative Production Example 3 was taken out, immersed in an aqueous 0.5% by mass sodium carbonate solution for 1 hour, then formed into a sheet while being washed with water with a creper, and then dried at 90 ° C. for 4 hours. A solid rubber (high-purity natural rubber H) was obtained by the procedure described above.

The solid rubber obtained above was evaluated as follows, and the results are shown in Table 1.

<Measurement of pH of rubber>
5 g of the obtained rubber was cut to 5 mm or less (about 1-2 × about 1-2 × about 1-2 (mm)) and placed in a 100 ml beaker, and 50 ml of distilled water at room temperature was added to 90 ° C. for 2 minutes. The temperature was raised, and then irradiation with microwaves (300 W) was performed for 13 minutes (15 minutes in total) while adjusting the temperature to be maintained at 90 ° C. Next, the immersion water was cooled with an ice bath to 25 ° C., and then the pH of the immersion water was measured using a pH meter.

<Measurement of nitrogen content>
(Acetone extraction (test piece preparation))
About 0.5 g of a sample obtained by chopping each solid rubber into 1 mm square was prepared. The sample was immersed in 50 g of acetone, and after 48 hours at room temperature (25 ° C.), the rubber was taken out and dried to obtain each test piece (extracted with anti-aging agent).
(Measurement)
The nitrogen content of the obtained test piece was measured by the following method.
The nitrogen content was determined by decomposing and gasifying each of the acetone-extracted test pieces obtained above using a trace nitrogen carbon measuring device “SUMIGRAPH NC95A (manufactured by Sumika Chemical Analysis Center)”. The nitrogen content was quantified by analyzing with a gas chromatograph “GC-8A (manufactured by Shimadzu Corporation)”.

<Measurement of phosphorus content>
The phosphorus content was determined using an ICP emission spectrometer (P-4010, manufactured by Hitachi, Ltd.).

<Measurement of gel content>
About 70 mg of a raw rubber sample cut to 1 mm × 1 mm was accurately weighed, 35 mL of toluene was added thereto, and the mixture was allowed to stand in a cool dark place for 1 week. Subsequently, centrifugation was performed to precipitate a gel component insoluble in toluene, the soluble component of the supernatant was removed, and only the gel component was solidified with methanol, and then dried and the mass was measured. The gel content (mass%) was determined by the following formula.
Gel content (mass%) = [mass mg after drying / mg of initial sample] × 100

<Heat aging resistance>
The Mooney viscosity ML (1 + 4) 130 ° C. of the solid rubber before and after being treated at 80 ° C. for 18 hours was measured according to JIS K 6300: 2001-1, and the heat aging index was calculated by the above formula.

According to Table 1, the modified natural rubber having a rubber pH in the range of 2 to 7 was excellent in heat aging resistance as compared with the rubber outside the range.

<Preparation of unvulcanized rubber composition and vulcanized rubber composition>
For each member, a chemical other than sulfur and a vulcanization accelerator was kneaded using a 1.7 L Banbury mixer according to the formulation shown in Tables 2 to 10 below to obtain a kneaded product. Next, using an open roll, sulfur and a vulcanization accelerator were kneaded into the obtained kneaded material to obtain an unvulcanized rubber composition.
Next, the obtained unvulcanized rubber composition was molded into a 2.1 mm sheet and vulcanized at 150 ° C. for 30 minutes to obtain a 2 mm vulcanized rubber composition. The obtained unvulcanized rubber composition and vulcanized rubber composition were evaluated for the following performance. The results are shown in each table. The reference comparative examples for each member were Comparative Examples 1-1, 2-1, 3-1, 4-1, 5-1, 6-1, 7-1, 8-1, 9-1.

<Processability (Mooney viscosity index)>
About the obtained unvulcanized rubber composition, Mooney viscosity at 130 ° C. was measured according to JIS K6300. The Mooney viscosity (ML _{1 + 4} ) of the reference comparative example was assumed to be 100, and the index was expressed by the following formula. The larger the index, the lower the Mooney viscosity and the better the workability.
(Mooney viscosity index) = (ML _{1 + 4} of reference comparative example) / (ML _{1 + 4 of} each formulation) × 100

<Low fuel consumption (rolling resistance index)>
The vulcanized rubber composition was measured using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), and 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 1%. The tan δ of the comparative example was set to 100, and indexed by the following calculation formula. The smaller the index, the better the rolling resistance.
(Rolling resistance index) = (tan δ of each formulation) / (tan δ of reference comparative example) × 100

<Degradation resistance index>
It was thermally deteriorated in an oven at 80 ° C. for 7 days, and this was regarded as a deteriorated product. The deteriorated product was subjected to a tensile test according to JIS K6251 and the elongation at break was measured. The index was displayed for each formulation with a reference comparative example of 100. The smaller the index, the greater the degree of deterioration.

<Flexible crack growth resistance>
Using the vulcanized rubber composition, a sample was prepared based on JIS K6260 “vulcanized rubber and thermoplastic rubber-dematcher bending crack test method”, a bending crack growth test was performed, and 70% elongation was repeated 1 million times. After bending the rubber sheet, the length of the generated crack was measured. The reciprocal of the measured value (length) of the reference comparative example was set to 100, and the index was displayed. The larger the index is, the more the crack growth is suppressed and the resistance to flex crack growth is excellent.

<Rubber strength index>
A tensile test was conducted according to JIS K6251 to measure elongation at break. The measurement results are shown as an index with the reference comparative example as 100. A larger index indicates better rubber strength (elongation at break).
(Rubber strength index) = (Elongation at break for each compound) / (Elongation at break in the reference comparative example) × 100

<Adhesive strength index>
Eight cords were arranged at equal intervals of 10 mm, and 0.7 mm thick topping rubber (unvulcanized rubber composition) was pressure-bonded from both sides. After the obtained rubber crimping cord was stored under the condition of 60% humidity, two rubber crimping cords were bonded together at an angle of 90 degrees, and reinforcing rubber was crimped on both sides thereof. The shape of the obtained pressure-bonded product was rectangular according to the shape of the vulcanization mold. After the pressure-bonded material was vulcanized at 165 ° C. for 20 minutes with the mold, a tear was placed between the two rubber-bonded cords bonded together in the resulting vulcanized material, and an Instron tensile tester was used. At a rate of 50 mm / min, the film was pulled in the direction of 180 degrees, and the peel force (kN / 25 mm) between the rubber crimping cords was evaluated. The results are shown as an index with the peel strength of the reference comparative example as 100. The larger the value, the better the adhesion between the cord and the topping rubber, and the better the durability.

<Break strength index>
In accordance with JIS K6251 “How to determine tensile properties of vulcanized rubber and thermoplastic rubber”, a tensile test was conducted using a No. 3 dumbbell, and the vulcanized rubber composition had an elongation at break (EB) and a tensile strength at break. (TB) was measured. In addition, EB × TB of the reference comparative example was set to 100, and EB × TB of each formulation was indicated by an index according to the following calculation formula. The larger the index, the better the breaking strength.
(Breaking strength index) = (EB × TB of each formulation) / (EB × TB of reference comparative example) × 100

<Runflat durability index>
The obtained unvulcanized rubber composition is molded into the shape of a reinforcing layer in the sidewall portion, and then bonded to other tire members and vulcanized to produce a test tire (tire size: 215 / 45R17). did. The test tire was run on the drum at an air pressure of 0 kPa at 80 km / h, the travel distance until the test tire having the sidewall reinforcing layer of each blending example was destroyed, and the travel distance of the reference comparative example was determined. The index was expressed as 100. A larger index indicates better run flat durability.

<Air permeability resistance index>
A rubber test piece having a diameter of 90 mm and a thickness of 1 mm made of the vulcanized rubber composition was prepared, and the air permeability coefficient (cc · cm / cm ² · sec / cmHg) was determined according to ASTM D-1434-75M Calculated. Then, the air permeability coefficient of the reference comparative example was expressed as an index (air permeability resistance index) using the following formula as the reference (100). It shows that it is hard to permeate | transmit air and it is excellent in air permeation resistance, so that an index | exponent is large.
(Air permeability resistance index) = (Air permeability coefficient of reference comparative example) / (Each air permeability coefficient) × 100

<Examples and Comparative Examples>
The various chemicals used in the examples are described below, and examples using the manufactured high-purity natural rubber are shown for each member.

<Under Tread>
Carbon black: Dia Black LH (N326, N ₂ SA: 84 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Viva Tec 400 (TDAE) manufactured by H & R
Anti-aging agent: NOCRACK RD (poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads manufactured by NOF Co., Ltd. Titanium stearate Sulfur: Kristex HSOT20 manufactured by Flexis (including 80% by mass of sulfur and 20% by mass of oil) Insoluble sulfur)
Vulcanization accelerator: Noxeller NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

From Tables 1 and 2, in the examples of the undertread, in which high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent are used in combination, low fuel consumption, processability, heat aging resistance, and deterioration resistance are exhibited. It became clear that it improved in a well-balanced manner.

<Sidewall>
BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, ML _{1 + 4} (100 ° C.): 40)
Carbon black: Show Black N550 (N ₂ SA: 42 m ² / g) manufactured by Cabot Japan
Silica: Ultrazil VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g)
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads stearic acid anti-aging agent manufactured by NOF Corporation 1: NOCRACK 6C (N-phenyl) manufactured by Ouchi Shinsei Chemical Industry -N '-(1,3-dimethylbutyl) -p-phenylenediamine) (6PPD)
Anti-aging agent 2: Antage RD (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Co., Ltd.
Sulfur: Seimi Sulfur (oil content: 10%) manufactured by Nippon Kiboshi Kogyo Co., Ltd.
Vulcanization accelerator 1: Noxeller NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Soxinol D manufactured by Sumitomo Chemical Co., Ltd.

From Tables 1 and 3, in Examples where high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent are used in combination in the sidewall, fuel economy, processability, heat aging resistance, and flex crack growth resistance It became clear that sex improved in a well-balanced manner.

<Wing>
BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, ML _{1 + 4} (100 ° C.): 40)
Carbon black: Dia Black LH (N326, N ₂ SA: 84 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: NOCRACK RD (poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads Tsubaki stearate manufactured by NOF Co., Ltd .: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical Noxeller NS made by Kogyo Co., Ltd.

From Tables 1 and 4, in the examples in which high purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent are used in combination in the wing, low fuel consumption, processability, heat aging resistance and rubber strength are well balanced. It became clear that it improved.

<Prightening>
SBR: Nipol 1502 (E-SBR, styrene content: 23.5 mass%, vinyl content: 18 mass%) manufactured by Nippon Zeon Co., Ltd.
Carbon black: N550 (N ₂ SA: 42 m ² / g, average particle size: 48 nm, DBP oil absorption: 113 ml / 100 g) manufactured by Cabot Japan
Silane coupling agent: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Oil: Viva Tec 400 (TDAE) manufactured by H & R
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads Tsubaki stearate manufactured by NOF Corporation: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Ouchi Shinsei Chemical Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.

From Tables 1 and 5, in the examples where the high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent are used in combination in the pleating, low fuel consumption, processability, heat aging resistance, adhesive strength and fracture It became clear that the strength improved in a well-balanced manner.

<Break topping>
Carbon black: N550 (N ₂ SA: 42 m ² / g, average particle size: 48 nm, DBP oil absorption: 113 ml / 100 g) manufactured by Cabot Japan
Silane coupling agent: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Oil: Viva Tec 400 (TDAE) manufactured by H & R
Organic acid cobalt: cost-F (cobalt stearate, cobalt content: 9.5% by mass) manufactured by Dainippon Ink & Chemicals, Inc.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads stearic acid anti-aging agent manufactured by NOF Corporation: NOCRACK 6C (N-phenyl-) manufactured by Ouchi Shinsei Chemical Co., Ltd. N ′-(1,3-dimethylbutyl) -p-phenylenediamine) (6PPD)
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller DZ manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

From Tables 1 and 6, in the example of using a high purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent in breaker topping, the fuel economy, workability, heat aging resistance and breaking strength are balanced. It became clear that it improved well.

<Clinch Apex>
BR: Nipol 1220 manufactured by Nippon Zeon Co., Ltd. (cis content: 96.5% by mass, vinyl content: 1% by mass)
Carbon black: Seast N (N330, N ₂ SA: 74 m ² / g, DBP oil absorption: 102 ml / 100 g) manufactured by Tokai Carbon Co., Ltd.
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Wax: Sunnock wax oil manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: Process X-140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: ANTAGE RD (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Industry Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads Tsubaki stearate manufactured by NOF Corporation: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Ouchi Shinsei Chemical Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.

From Tables 1 and 7, in the clinch apex, in the examples in which high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent are used in combination, low fuel consumption, processability, heat aging resistance and breaking strength are obtained. It became clear that it improved in a well-balanced manner.

<Bead Apex>
SBR: Nipol 1502 manufactured by Nippon Zeon Co., Ltd. (E-SBR, styrene content: 23.5 mass%, ML (1 + 4) 100 ° C .: 52)
Carbon black: Seast N (N330, N ₂ SA: 74 m ² / g, DBP oil absorption: 102 ml / 100 g) manufactured by Tokai Carbon Co., Ltd.
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Anti-aging agent: ANTAGE RD (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Industry Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads Tsubaki stearate manufactured by NOF Corporation: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Ouchi Shinsei Chemical Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.

From Tables 1 and 8, in the bead apex, an example using a high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent, the fuel economy, workability, heat aging resistance and breaking strength are It became clear that it improved in a well-balanced manner.

<Sidewall reinforcement layer>
Carbon Black: Show Black N220 (N ₂ SA: 111 m ² / g, DBP oil absorption: 115 ml / 100 g) manufactured by Cabot Japan
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: NOCRACK RD (poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads manufactured by NOF Co., Ltd. Titanium stearate Sulfur: Kristex HSOT20 manufactured by Flexis (including 80% by mass of sulfur and 20% by mass of oil) Insoluble sulfur)
Vulcanization accelerator: Noxeller NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

From Tables 1 and 9, in the side wall reinforcing layer, in the examples in which high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent were used in combination, low fuel consumption, workability, heat aging resistance, breaking strength It was also revealed that run-flat durability improved in a well-balanced manner.

<Inner liner>
ENR: ENR25 (Epoxidation rate: 25 mol%) manufactured by Kungpu Langurs
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent 1: NXT silane (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Performance Materials
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Anti-aging agent: ANTAGE RD (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) manufactured by Kawaguchi Chemical Industry Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads Tsubaki stearate manufactured by NOF Corporation: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Ouchi Shinsei Chemical Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.

From Tables 1 and 10, in the examples where the high purity natural rubber having a pH of 2 to 7 and the specific silane coupling agent are used in combination in the inner liner, low fuel consumption, workability, heat aging resistance, breaking strength and resistance It became clear that air permeability improved in a well-balanced manner.

From the above results, the pneumatic tire having each tire member using a high-purity natural rubber having a pH of 2 to 7 and a specific silane coupling agent can improve the various performances such as fuel efficiency in a well-balanced manner. found.

Claims (11)

A rubber composition comprising a modified natural rubber having a high purity and a pH adjusted to 2 to 7, carbon black and / or a white filler, and a silane coupling agent represented by the following formula (S1) Pneumatic having at least one member selected from the group consisting of an under tread, a sidewall, a wing, a pret wrap, a break topping, a clinch apex, a bead apex, a side wall reinforcing layer, and an inner liner manufactured using tire.

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ] The pneumatic tire according to claim 1, wherein the modified natural rubber is obtained by removing a non-rubber component of the natural rubber and then treating with an acidic compound, and has a pH of 2-7. The pneumatic tire according to claim 1, wherein the modified natural rubber is obtained by washing a saponified natural rubber latex and further treating with an acidic compound, and having a pH of 2-7. The pneumatic tire according to claim 1, wherein the modified natural rubber is obtained by washing deproteinized natural rubber latex and further treating with an acidic compound, and having a pH of 2-7. The pneumatic tire according to any one of claims 1 to 4, wherein the phosphorus content of the modified natural rubber is 200 ppm or less. The pneumatic tire according to any one of claims 1 to 5, wherein the modified natural rubber has a nitrogen content of 0.15 mass% or less. The pH is measured by cutting the modified natural rubber into 2 mm squares of each side and immersing in distilled water, extracting at 90 ° C. for 15 minutes while irradiating with microwaves, and measuring the immersion water using a pH meter. The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is a calculated value. The modified natural rubber has a heat aging index represented by the following formula of 75 to 120% with respect to Mooney viscosity ML (1 + 4) 130 ° C. measured according to JIS K 6300: 2001-1. The pneumatic tire according to Items 1 to 7.

The pneumatic tire according to claim 1, wherein the white filler is silica. 10. The pneumatic according to claim 1, wherein the content of the silane coupling agent is 0.1 to 20 parts by mass with respect to 100 parts by mass of the total content of the carbon black and the white filler. tire. The pneumatic tire according to any one of claims 1 to 10, wherein the modified natural rubber is produced without going through a mastication step.