JP4541475B2 - Method for producing rubber composition and rubber composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, fracture resistance, without reducing the resistance to tear resistance, are those concerning the manufacturing method of a rubber composition capable of improving the low heat buildup, and a rubber composition prepared by this method.
[0002]
[Prior art]
Rubber applied to the tread of pneumatic tires, especially the base of cap / base structures, requires not only low heat buildup but also fracture resistance and tear resistance. There is a method of increasing the elongation at break of rubber.
However, this increases the strain deformation, which deteriorates the low heat buildup of the tire.
[0003]
Therefore, there is a technique for reducing the heat generation of the rubber composition by blending a specific hydrazide compound (see: JP-A-10-139934 and JP-A-10-330549).
[0004]
[Problems to be solved by the invention]
However, the hydrazide compound is affected by zinc white and kneading temperature during the rubber kneading process, and therefore a specific production method is required to obtain a rubber composition having desired characteristics. It has been found.
Therefore, the present invention provides a rubber composition containing a specific hydrazide compound, which is excellent as a rubber exothermic improver, a tread that has fracture resistance and tear resistance, and can sufficiently exhibit low heat generation, in particular, An object of the present invention is to provide a method for producing a rubber composition suitable for the rubber of the base part of the cap / base structure.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
(1) The method for producing a rubber composition of the present invention is a rubber kneading step (so-called non-pro kneading step) before adding a vulcanizing agent, and a rubber component consisting of at least one of natural rubber and diene-based synthetic rubber is 100 weights. In addition, 0.1 to 5 parts by weight of at least one hydrazide compound represented by the following general formula [Chemical Formula 2], 0.2 to 5 parts by weight of zinc white, and carbon black are simultaneously added. And kneading at a maximum temperature (so-called drop temperature) of 130 ° C to 170 ° C.
[Chemical 2]
(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, or an aryl group, and may contain at least one heteroatom of O, N, and S. Good.)
The amount of the carbon black click, when 20 to 60 parts by weight per 100 parts by weight of the rubber component, when the rubber composition as a tread rubber, preferable in terms of reinforcing and the like. Further, in the rubber kneading step, silica is also charged and kneaded, and the blending amount is preferably 20 parts by weight or less with respect to 100 parts by weight of the rubber component from the viewpoint of heat generation durability and the like.
Note that the timing of carbon black or silica charging is not affected by the timing of hydrazide compound charging.
(2) The rubber composition of the present invention is characterized by the kites produced by the above production method. When the rubber composition is applied to a tread and the tread has a cap / base structure, it is effective to apply to the base portion.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the blending amount of the hydrazide compound is set to 0.1 to 5 parts by weight with respect to 100 parts by weight of the rubber component. If the amount exceeds 5 parts by weight, the unvulcanized viscosity of the rubber increases, which is not preferable. From the same viewpoint, the amount is preferably 0.5 to 3 parts by weight.
Examples of the hydrazide compound of the present invention include 1-hydroxy-N ′-(1-methylethylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N ′-(1-methylpropylidene) -2-naphthoic acid hydrazide, 1 -Hydroxy-N '-(1-methylbutylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N'-(1,3-dimethylbutylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N'- (2-Furylmethylene) -2-naphthoic acid hydrazide, 3-hydroxy-N ′-(1-methylethylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N ′-(1-methylpropylidene) -2- Naphthoic acid hydrazide, 3-hydroxy-N ′-(1-methylbutylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N ′-(1,3- Examples include methylbutylidene) -2-naphthoic acid hydrazide and 3-hydroxy-N ′-(2-furylmethylene) -2-naphthoic acid hydrazide. Among these, 1-hydroxy-N ′-( 1-methylethylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N '-(1-methylpropylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N'-(1,3-dimethylbutylidene)- 2-naphthoic acid hydrazide, 1-hydroxy-N ′-(2-furylmethylene) -2-naphthoic acid hydrazide, 3-hydroxy-N ′-(1-methylethylidene) -2-naphthoic acid hydrazide, 3-hydroxy- N ′-(1-methylpropylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N ′-(1,3-dimethylbutylidene) -2 Naphthoic acid hydrazide, 3-hydroxy -N '- (2-furyl-methylene) -2-naphthoic acid hydrazide. The hydrazide compound of the present invention may be used alone or in combination of two or more.
These compounds can be synthesized according to the synthesis method described in JP-A-10-330549.
Moreover, the zinc white to be added simultaneously with the hydrazide compound is 0.2 to 5 parts by weight with respect to 100 parts by weight of the rubber component. This is because the desired low exothermic property cannot be obtained, and if it exceeds 5 parts by weight, the rubber is cramped, and conversely the low exothermic property is deteriorated.
[0007]
In addition, the temperature inside the system rises during rubber kneading, so when it reaches a certain temperature (falling temperature), it cools down and lowers the temperature of the system. ".
The maximum temperature is set to 130 to 170 ° C. in the present invention. However, if the temperature is less than 130 ° C., the hydrazide compound does not sufficiently react with carbon black and the rubber polymer, and the intended low heat build-up cannot be obtained. This is because if it exceeds ° C., the fracture resistance of the rubber is lowered, which is not preferable.
Further, in order to obtain sufficient reinforcement as a tread rubber, it is preferable to blend 20 parts by weight or more of carbon black, and 60 parts by weight or less is preferable from the viewpoint of low heat build-up.
When silica is blended, the amount is preferably 20 parts by weight or less from the viewpoint of low heat generation.
[0008]
Furthermore, in the production method of the present invention, the hydrazide compound and zinc white need to be added at the same time, but before the addition, they may be mixed in advance with a blender or the like, and this mixture may be added.
The diene-based synthetic rubber that can be suitably used in the present invention is not particularly limited, and examples thereof include solution polymerization or emulsion polymerization styrene / butadiene rubber and butadiene rubber.
When using the production method of the present invention, other compounding agents usually used in the rubber industry, for example, vulcanization accelerators, vulcanization accelerators, anti-aging agents, etc. can be appropriately compounded by conventional methods and kneaded. Subsequent vulcanization can also be performed by conventional methods.
[0009]
【Example】
The present invention will be specifically described below based on examples.
As shown in Table 1, the rubber kneading step was divided into three kneading steps, and the rubber component and each compounding agent were kneaded. Sulfur as a vulcanizing agent is charged in the third kneading step, and the “rubber kneading step before adding the vulcanizing agent” of the present invention corresponds to the first kneading step and the second kneading step. .
Each manufactured rubber composition was applied to all tread parts, 11R22.5 tires were prepared by a conventional method, and performance was measured by the following method.
<Evaluation of low heat generation>
For each tire, a drum test was performed under conditions of constant speed and step load, the temperature at a constant depth position inside the tread made of the rubber composition of each example was measured, and the value of Comparative Example 1 was set to 100, The index was displayed. The lower the value, the lower the tire temperature and the lower the heat generation.
[0010]
<Evaluation of fracture resistance and tear resistance>
Each tire was actually used, and the tire was run to the remaining groove of 3 mm. The area of the rubber missing portion per 30 cm circumference of the rubber surface of the tire was determined, and the value of Comparative Example 1 was represented as an index. The larger the value, the wider the missing area, and the lower the fracture resistance and tear resistance.
[0011]
[Table 1]
(note)
The used hydrazide is represented by the following chemical formula [Chemical Formula 3].
[Chemical 3]
The maximum temperature of the third kneading step is 110 ° C. in all examples.
Carbon black: N220
Vulcanization accelerator: Noxeller NS
[0012]
From the above results, Comparative Example 1 in which hydrazide was blended was effective for low exothermic property, fracture resistance, and tear resistance as compared to Comparative Example 5 in which it was not blended. Compared to Comparative Example 1, it can be seen that each performance is improved comprehensively.
[0013]
【The invention's effect】
As described above, according to the production method of the present invention, the effect of low exothermic property of the hydrazide compound can be surely obtained, and the pneumatic tire obtained by applying the rubber composition by this method to a tread is a conventional product. In comparison, it has exceptionally low heat build-up, fracture resistance, and tear resistance.

Claims (5)

Among the hydrazide compounds represented by the following general formula [Chemical Formula 1] with respect to 100 parts by weight of the rubber component consisting of at least one of natural rubber and diene-based synthetic rubber in the rubber kneading step before adding the vulcanizing agent 0.1-5 parts by weight of at least one kind, 0.2-5 parts by weight of zinc white, and carbon black are simultaneously added and kneaded at a maximum temperature of 130 ° C to 170 ° C. A method for producing a rubber composition.
(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, or an aryl group, and may contain at least one heteroatom of O, N, and S. Good.)   The method for producing a rubber composition according to claim 1, wherein the blending amount of the carbon black is 20 to 60 parts by weight with respect to 100 parts by weight of the rubber component.   The rubber composition according to claim 1 or 2, wherein silica is also added and kneaded in the rubber kneading step, and the amount of the silica compound is 20 parts by weight or less with respect to 100 parts by weight of the rubber component. Production method. Among the hydrazide compounds represented by the following general formula [Chemical Formula 1] with respect to 100 parts by weight of the rubber component consisting of at least one of natural rubber and diene-based synthetic rubber in the rubber kneading step before adding the vulcanizing agent At least one of 0.1 to 5 parts by weight, zinc white of 0.2 to 5 parts by weight, and carbon black of 20 to 60 parts by weight are added simultaneously, and the maximum temperature is 130 ° C to 170 ° C and mixed. A rubber composition produced by kneading.
(Wherein R ₁ And R ₂ Represents independently an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, or an aryl group, and may contain at least one heteroatom selected from O, N, and S. ) Among the hydrazide compounds represented by the following general formula [Chemical Formula 1] with respect to 100 parts by weight of the rubber component consisting of at least one of natural rubber and diene-based synthetic rubber in the rubber kneading step before adding the vulcanizing agent 0.1-5 parts by weight of at least one kind, 0.2-5 parts by weight of zinc white, 20-60 parts by weight of carbon black, and 20 parts by weight or less of silica are simultaneously charged, and the maximum temperature is set. A rubber composition produced by kneading at 130 to 170 ° C.
(Wherein R ₁ And R ₂ Represents independently an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, or an aryl group, and may contain at least one heteroatom selected from O, N, and S. )