JP2008156419A - Method for producing rubber composition, rubber composition obtained thereby, and tire using the rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rubber composition by which not only the hardness can be sufficiently heightened and the heat build-up can be reduced, but also the breaking elongation can be improved. <P>SOLUTION: The method for producing the rubber composition includes obtaining a solution by dissolving a diene rubber (1) in a solvent, adding a phenol resin and/or a modified phenol resin, and carbon black to the resultant solution and stirring, treating the solution with a poor solvent to precipitate the components and to provide a wet master batch, and kneading the prepared wet master batch with a diene rubber (2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a rubber composition, a rubber composition obtained thereby, and a tire using the rubber composition.

  Conventionally, a rubber composition used for a bead apex or the like has been required to have high hardness, and a rubber component, a filler such as carbon black or silica, a phenol resin or a modified phenol resin are collectively put into a kneader. It is charged and kneaded (for example, see Patent Document 1). When the rubber component is kneaded prior to the filler, the base kneading may be divided into two steps or three steps. However, in any case, the filler, the phenol resin, and the modified phenol resin are kneaded at the same time.

  The methods to increase the hardness are as follows: (1) A method of highly filling carbon black, a method of highly filling phenolic resin or modified phenolic resin, (2) A method of highly filling sulfur, or a highly filled vulcanization accelerator. And (3) a technique of using a vulcanization accelerating auxiliary such as a citraconic imide compound or an organic thiosulfate compound.

  If these techniques are used, high hardness can be obtained. However, the method (1) has a disadvantage in that the heat generation becomes high. In the case of the method (2), there is a disadvantage that elongation at break is reduced. Furthermore, in the case of the method (3), the combined use with the method (1) and the method (2) becomes indispensable, and the same problems as the method (1) and the method (2) occur.

JP 2004-2588 A

  An object of this invention is to provide the manufacturing method of the rubber composition which not only raises hardness sufficiently and makes exothermic property low but can also improve break elongation.

  The present invention includes (A) a step of dissolving a diene rubber (1) in a solvent to obtain a solution, and (B) a phenol resin and / or a modified resin in 100 wt parts of the diene rubber (1). A step of adding and stirring 3 to 100 parts by weight of phenol resin and 40 to 150 parts by weight of carbon black, (C) A step of preparing a wet masterbatch by treating the solution with a poor solvent while stirring and reprecipitation , (D) a step of kneading the obtained wet masterbatch and the diene rubber (2), and 0.5 to 25 weights of phenol resin and / or modified phenol resin with respect to 100 parts by weight of the rubber component And a method for producing a rubber composition containing 40 to 150 parts by weight of carbon black.

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

  Furthermore, the present invention relates to a tire having a bead apex, a tread, a base tread, a breaker or a carcass ply using the rubber composition.

  According to the present invention, a wet masterbatch containing a diene rubber (1), a phenolic resin and / or a modified phenolic resin and carbon black is prepared in a predetermined step, and then the prepared wet masterbatch and the diene rubber (2). Can be used to produce a rubber composition that not only sufficiently increases the hardness and lowers the heat build-up, but also reduces the cost of the raw materials.

  The rubber composition produced by the production method of the present invention contains a total of 0.5 to 25 parts by weight of phenolic resin and / or modified phenolic resin and a total of 40 to 150 parts by weight of carbon black with respect to 100 parts by weight of all rubber components. To do.

  The compounding amount of the phenol resin and / or the modified phenol resin is 0.5 parts by weight or more, preferably 5 parts by weight or more with respect to 100 parts by weight of the total rubber component. When the blending amount of the phenol resin and / or the modified phenol resin is less than 0.5 parts by weight, sufficient hardness cannot be obtained. Moreover, the compounding quantity of a phenol resin and / or a modified phenol resin is 25 weight part or less, Preferably it is 20 weight part or less. When the blending amount of the phenol resin and / or the modified phenol resin exceeds 25 parts by weight, the elongation at breakage deteriorates.

  The compounding amount of carbon black is 40 parts by weight or more, preferably 50 parts by weight or more with respect to 100 parts by weight of the total rubber component. If the blending amount of carbon black is less than 40 parts by weight, sufficient hardness cannot be obtained. The blending amount of carbon black is 150 parts by weight or less, preferably 130 parts by weight or less. When the blending amount of carbon black exceeds 150 parts by weight, the exothermic property becomes high.

  Hereinafter, the manufacturing method of the rubber composition which satisfy | fills these conditions in this invention is demonstrated.

  The production method of the present invention comprises (A) a step of obtaining a solution by dissolving the diene rubber (1) in a solvent, and (B) adding a phenol resin and / or a modified phenol resin and carbon black to the solution. A step of stirring, (C) a step of treating the solution with a poor solvent while stirring to reprecipitate the rubber composition (1) to prepare a wet master batch, and (D) in steps (A) to (C). A step of kneading the obtained wet masterbatch and the diene rubber (2) is included.

  In the step (A), the diene rubber (1) is dissolved in a solvent to obtain a solution.

  The diene rubber (1) is not particularly limited as long as it is used for tires. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene Examples thereof include rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and ethylene propylene diene rubber (EPDM). These diene rubbers (1) may be used alone or in combination of two or more.

  Examples of the solvent for dissolving the diene rubber (1) include aromatic compounds such as toluene and xylene, hexane, and the like. The solvent may be a sufficient amount relative to the diene rubber (1). However, if the amount is too small, the resulting solution becomes a concentrated solution, and the phenol resin and / or modified phenol resin and carbon black tend not to be dispersed. If the amount is too large, a large amount of poor solvent tends to be required in the reprecipitation step of the rubber composition (1).

  In the step (B), a phenol resin and / or a modified phenol resin and carbon black are added to the solution obtained in the step (A) and stirred.

  In the step (B), the phenol resin and / or the modified phenol resin and the carbon black are added so that the phenol resin and / or the modified phenol resin and the carbon black are entangled to form a sphere. Here, the larger the amount of carbon black blended, the larger the sphere and the higher the rubber composition (2) finally produced. Therefore, in the step (B), the phenolic resin and / or the modified phenolic resin and the carbon black are highly filled as compared with the case of producing the conventional rubber composition, but the spheres formed here do not become fracture nuclei. It is necessary to make it the compounding quantity.

  The phenol resin is not particularly limited, and examples thereof include those obtained by reacting phenols with aldehydes such as formaldehyde, acetaldehyde and furfural with an acid or alkali catalyst.

  The modified phenolic resin is not particularly limited. For example, phenol modified with cashew oil, tall oil, linseed oil, rapeseed oil, soybean oil, unsaturated fatty acid, rosin, alkylbenzene resin, aniline, melamine, etc. Examples thereof include resins. The modification method is not particularly limited as long as it is modified using these methods.

  As the phenol resin and / or the modified phenol resin, a modified phenol resin is preferable, a cashew oil-modified phenol resin or a rosin-modified phenol resin is more preferable, and a cashew oil-modified phenol resin is more preferable because the hardness can be improved.

  In the step (B), the compounding amount of the phenol resin and / or the modified phenol resin is 3 parts by weight or more, preferably 5 parts by weight or more, more preferably 7 parts by weight or more with respect to 100 parts by weight of the diene rubber (1). It is. When the blending amount of the phenol resin and / or the modified phenol resin is less than 3 parts by weight, a sufficiently large sphere is not formed and sufficient hardness cannot be obtained. Moreover, the compounding quantity of a phenol resin and / or a modified phenol resin is 100 weight part or less, Preferably it is 90 weight part or less. When the blending amount of the phenol resin and / or the modified phenol resin exceeds 100 parts by weight, the dispersion of the phenol resin and / or the modified phenol resin is deteriorated, and the elongation at break is deteriorated.

  Although it does not necessarily restrict | limit as carbon black, For example, the thing of grades, such as SAF, ISAF-HM, ISAF-LM, ISAF-HS, HAF, and FEF, can be used.

  In the step (B), the compounding amount of carbon black is 40 parts by weight or more, preferably 45 parts by weight or more with respect to 100 parts by weight of the diene rubber (1). When the blending amount of carbon black is less than 40 parts by weight, a sufficiently large sphere is not formed and sufficient hardness cannot be obtained. The blending amount of carbon black is 150 parts by weight or less, preferably 130 parts by weight or less, more preferably 100 parts by weight or less. When the blending amount of the carbon black exceeds 150 parts by weight, the formed sphere is too large, and the unevenness of the kneaded dough of the wet masterbatch to be prepared becomes large, resulting in poor dispersion. For example, when 60 parts by weight of carbon black is used, the size of the sphere to be formed is about 30 μm, and a sphere having a size that does not become a fracture nucleus is formed.

  Stirring can be performed by any method.

  In the step (C), the solution is treated with a poor solvent while being stirred and reprecipitated, and then a wet master batch is prepared.

  The poor solvent is not particularly limited, and examples thereof include lower alcohols such as methanol and ethanol.

  In order to reprecipitate the rubber composition for preparing the wet masterbatch by treating the rubber solution in which the phenol resin and / or the modified phenol resin and carbon black obtained in the step (B) are dispersed with a poor solvent, A method of adding the poor solvent while stirring the solution or a method of adding the poor solvent while stirring the rubber solution can be used. At this time, the amount of the poor solvent may be sufficient with respect to the solvent used for dissolving the rubber, but if it is too small, the rubber composition for preparing the wet masterbatch tends not to be re-precipitated well, If too much, there is a tendency to use a poor solvent in vain.

  In the step (C), before treatment with a poor solvent, a substance that does not inhibit the formation of a sphere composed of a phenol resin and / or a modified phenol resin and carbon black, such as zinc oxide and oil, may be added. There is no restriction | limiting in particular as a zinc oxide, The thing conventionally used for tires can be used. The oil is not particularly limited, but for example, aroma oil, mineral oil, etc. can be used.

  The rubber composition for preparing a wet masterbatch that has been treated with a poor solvent and reprecipitated can completely remove the solvent by vacuum drying or the like to prepare a wet masterbatch.

  In addition, used solvents, poor solvents, oils, and the like can be separated and reused by distillation or the like.

  In the step (D), the wet master batch and the diene rubber (2) obtained in the steps (A) to (C) are kneaded.

  Here, the diene rubber (2) can be the same as the diene rubber (1).

  Further, the blending ratio of the diene rubber (1) and the diene rubber (2) (diene rubber (1) / diene rubber (2)) is preferably 1/5 or more, and more preferably 1/4 or more. When the compounding ratio is less than 1/5, the dispersibility of the diene rubber (1) and the diene rubber (2) tends to deteriorate. The blending ratio is preferably 2/1 or less, and more preferably 3/2 or less. When the blending ratio exceeds 2/1, the blending amount of carbon black with respect to the diene rubber (2) is decreased in the master batch, and it tends to be difficult to obtain sufficient hardness.

  When the wet masterbatch and the diene rubber (2) are kneaded, a Banbury mixer or a kneader can be used.

  In the step (D), in addition to the wet masterbatch and the diene rubber (2), compounding agents conventionally used for tires, for example, various antioxidants, zinc oxide, stearic acid, sulfur, various vulcanizations Accelerators, vulcanization acceleration aids and the like can also be used. In the step (D), phenol resin and / or modified phenol resin and carbon black may be kneaded together.

In the case where sulfur is used in the step (D), insoluble sulfur is preferable because of its excellent dispersibility. Specifically, for example, Kristex HSOT20 manufactured by Flexis, Sanfel EX manufactured by Sanshin Chemical Industry Co., Ltd. can give. Here, insoluble sulfur refers to high molecular weight sulfur in which the eight-membered cyclic structure of S ₈ undergoes radical cleavage and connects them in a chain, and is insoluble in carbon disulfide and rubber-like hydrocarbons. It is.

  When sulfur is used in the step (D), the amount of sulfur is preferably 5 parts by weight or more and more preferably 5.25 parts by weight or more with respect to 100 parts by weight of all rubber components. If the amount of sulfur is less than 5 parts by weight, sufficient hardness tends not to be obtained. The amount of sulfur is preferably 8 parts by weight or less, more preferably 7 parts by weight or less, and even more preferably 6 parts by weight or less. When the amount of sulfur exceeds 8 parts by weight, not only the surface is easily bloomed during processing but also during vulcanization, the elongation at break tends to deteriorate. In addition, when insoluble sulfur is contained as sulfur, the sulfur content represents the sulfur content excluding the oil in the insoluble sulfur.

  The rubber composition obtained by the production method of the present invention can enlarge a sphere containing carbon black and a phenol resin sufficiently to the extent that there is no problem in dispersibility, so that a bead apex can be obtained because the dispersibility and hardness can be balanced. , Tread, base tread, breaker or carcass ply, and it is particularly preferable to use as a bead apex.

  The tire of the present invention is produced by a normal method using the rubber composition produced by the production method of the present invention. That is, the rubber composition produced by the production method of the present invention is extruded in accordance with the shape of each member of a tire, preferably a bead apex, at an unvulcanized stage, and is subjected to a usual method on a tire molding machine. An unvulcanized tire is formed by molding with. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain the tire of the present invention.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Ｎ−シクロヘキシルチオ−フタルアミド（ＣＴＰ）：大内新興化学工業（株）製のＣＴＰ Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber (NR): RSS # 3
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Carbon black: Show Black N550 manufactured by Cabot Japan
Silica: 115GR manufactured by Rhodia
Modified phenolic resin: PR12686 (cashew oil-modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Zinc oxide: Mitsui Metal Mining Co., Ltd. Stearic acid: Nippon Oil & Fats Co., Ltd. Insoluble sulfur: Flexis Co., Ltd. Christex HSOT20 (insoluble sulfur containing 80% sulfur and 20% oil content)
Vulcanization accelerator (1): Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator (2): Noxeller H (Hexamethylenetetramine (HMT)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator PK900: PERKALINK900 (1,3-bis (citraconimidomethyl) benzene) manufactured by Flexis

N-cyclohexylthio-phthalamide (CTP): CTP manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Preparation of master batches 1 to 4)
In accordance with the formulation shown in Table 1, NR was dissolved in toluene to obtain a solution (step (A)). The modified phenolic resin, carbon black and zinc oxide were added thereto and dissolved while stirring (step (B)). While stirring this solution, methanol was poured all at once and the rubber was reprecipitated all at once. This re-precipitate was vacuum-dried to prepare wet master batches 1 to 4 (step (C)).

  Each composition at the time of preparing the master batches 1 to 4 is shown in Table 1.

Examples 1-4 and Comparative Examples 1-4
According to the formulation shown in Table 2, a Banbury mixer was used to knead insoluble sulfur, a vulcanization accelerator and chemicals other than CTP to obtain a kneaded product. Next, using an open roll, insoluble sulfur, a vulcanization accelerator and CTP were added to the obtained kneaded material and kneaded to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized for 12 minutes under the condition of 170 ° C. to produce vulcanized rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 4 (step (D)). ).

(Viscoelasticity test)
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho Co., Ltd., the complex elastic modulus E * (MPa) of the vulcanized rubber composition under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%. ) And loss tangent tan δ were measured. In addition, it shows that rigidity is so high that E * is large and steering stability is excellent, and exothermic property is low and it is excellent, so that tan-delta is small.

(Tensile test)
Using a No. 3 dumbbell-shaped test piece composed of the vulcanized rubber composition, a tensile test was conducted according to JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Tensile Properties”, and elongation at break EB (%) Was measured. In addition, it shows that it is excellent, so that EB is large.

  The evaluation results are shown in Table 2.

Claims (7)

(A) A step of dissolving the diene rubber (1) in a solvent to obtain a solution,
(B) To the solution,
For 100 parts by weight of diene rubber (1),
Adding and stirring 3-100 parts by weight of phenolic resin and / or modified phenolic resin, and 40-150 parts by weight of carbon black;
(C) A step of preparing a wet master batch by treating the solution with a poor solvent while stirring and reprecipitation.
(D) including a step of kneading the obtained wet masterbatch and the diene rubber (2),
A method for producing a rubber composition comprising 0.5 to 25 parts by weight of a phenol resin and / or a modified phenol resin and 40 to 150 parts by weight of carbon black with respect to 100 parts by weight of a rubber component. A rubber composition obtained by the production method according to claim 1. A tire having a bead apex using the rubber composition according to claim 2. A tire having a tread using the rubber composition according to claim 2. A tire having a base tread using the rubber composition according to claim 2. A tire having a breaker using the rubber composition according to claim 2. A tire having a carcass ply using the rubber composition according to claim 2.