JP2021172173A - tire - Google Patents

Abstract

To provide a tire having a sidewall that achieves both of ozone resistance and cutting resistance.SOLUTION: A tire has a sidewall composed of a rubber composition. In the rubber composition, carbon black of 50 pts.mass or more is contained relative to 100 pts.mass of a rubber component containing an isoprene rubber of 20-50 mass%, a 1,2-polybutadiene component of 5 mass% or more and a cis-1,4-polybutadiene component of 20 mass% or more. The thickness at a maximum width position in the tire axial direction is 1.5 mm or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire having a predetermined sidewall.

Tire sidewalls tend to crack due to the effects of atmospheric ozone during long-term use. Therefore, an anti-aging agent or the like is generally added to the rubber composition used for the sidewall for the purpose of imparting performance such as ozone resistance (see Patent Document 1).

Japanese Unexamined Patent Publication No. 7-62156

However, the anti-aging agent merely prevents the deterioration of rubber at the expense of itself, and further improvement of ozone resistance is required to prevent cracks in the tire.

An object of the present invention is to provide a tire having a sidewall that has both ozone resistance and cut resistance.

As a result of diligent studies to solve the above problems, the present inventors have added a predetermined amount of carbon black to a rubber component containing a predetermined amount of each of an isoprene-based rubber, a 1,2-polybutadiene component and a cis-1,4-polybutadiene component. It has been found that the above-mentioned problems can be solved by using a sidewall having a thickness of 1.5 mm or more at a predetermined position, which is composed of a rubber composition using the above-mentioned material, and further studies have been carried out to complete the present invention.

That is, the present invention
[1] Isoprene-based rubber 20 to 50% by mass, preferably 20 to 46% by mass, more preferably 20 to 43% by mass, more preferably 20 to 40% by mass, more preferably 24 to 40% by mass, more preferably. 27-40% by mass, more preferably 30-40% by mass, 1,2-polybutadiene component 5% by mass or more, preferably 5-40% by mass, more preferably 5-35% by mass, more preferably 5-30. By mass%, more preferably 10 to 30% by mass, more preferably 15 to 30% by mass, more preferably 20 to 30% by mass, and cis-1,4-polybutadiene component 20% by mass or more, preferably 20 to 80% by mass. %, More preferably 20 to 75% by mass, more preferably 20 to 70% by mass, more preferably 25 to 65% by mass, more preferably 25 to 60% by mass, more preferably 30 to 60% by mass, more preferably. With respect to 100 parts by mass of the rubber component containing 30 to 55% by mass, more preferably 35 to 55% by mass.
It is composed of a rubber composition containing 50 parts by mass or more of carbon black, preferably 50 to 150 parts by mass, more preferably 52 to 150 parts by mass, more preferably 53 to 110 parts by mass, and more preferably 55 to 80 parts by mass.
The thickness in the tire axial direction at the maximum width position of the tire is 1.5 mm or more, preferably 1.5 to 3.0 mm, more preferably 1.5 to 2.7 mm, more preferably 1.5 to 2.5 mm, or. , Preferably 1.7 mm or more, more preferably 1.7 to 3.0 mm, more preferably 1.7 to 2.7 mm, more preferably 1.7 to 2.5 mm, or preferably 1.8 mm or more. More preferably 1.8 to 3.0 mm, more preferably 1.8 to 2.7 mm, more preferably 1.8 to 2.5 mm, or preferably 2.0 mm or more, more preferably 2.0 to 3 Tires with sidewalls of 0.0 mm, more preferably 2.0 to 2.7 mm, more preferably 2.0 to 2.5 mm.
[2] The tire according to the above [1], wherein the 1,2-polybutadiene component has a melting point of 50 to 150 ° C., preferably 60 to 140 ° C., more preferably 65 to 135 ° C., and more preferably 70 to 130 ° C.
[3] The 1,2-vinyl bond content of the 1,2-polybutadiene component is 70% or more, preferably 80% or more, more preferably 90% or more, more preferably 94% or more. 2] The tires listed,
[4] The crystallinity of the 1,2-polybutadiene component is 5 to 50%, preferably 10 to 45%, more preferably 15 to 40%, more preferably 15 to 36%, and even more preferably 18 to 36%. The tire according to any one of the above [1] to [3].
[5] For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,2-vinyl bond content by the mass fraction in the rubber component, the total defined as the sum of these values. The 1,2-vinyl bond content is 3.5% or more, preferably 3.5 to 40.0%, more preferably 3.5 to 35.0%, more preferably 4.0 to 35.0%. The tire according to any one of the above [1] to [4], which is more preferably 4.5 to 30.0%, more preferably 5.0 to 30.0%.
[6] The cis-1,4-bond content of the cis-1,4-polybutadiene component is 80% or more, preferably 90% or more, more preferably 94% or more, more preferably 97% or more [1]. ] To the tire according to any one of [5].
[7] For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,4-bond content by the mass fraction in the rubber component, a total of 1 defined as the sum of these values is calculated. , 4-Binding content is 66.0% or more, preferably 66.0-98.0%, 70.0-98.0%, 80.0-97.0%, 80.0-96.0% , The tire according to any one of the above [1] to [6], which is 90.0 to 95.0%.
Regarding.

According to the present invention, it is possible to provide a tire having a sidewall that has both ozone resistance and cut resistance.

This is an example of a schematic partial cross-sectional view of a tire.

One embodiment is based on 100 parts by mass of a rubber component containing 20 to 50% by mass of isoprene rubber, 5% by mass or more of a 1,2-polybutadiene component, and 20% by mass or more of a cis-1,4-polybutadiene component. The tire is made of a rubber composition containing 50 parts by mass or more of carbon black, and has a sidewall having a thickness of 1.5 mm or more in the tire axial direction at the maximum width position of the tire.

The melting point of the 1,2-polybutadiene component is preferably 50 to 150 ° C.

The 1,2-vinyl bond content of the 1,2-polybutadiene component is preferably 70% or more.

The crystallinity of the 1,2-polybutadiene component is preferably 5 to 50%.

For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,2-vinyl bond content by the mass fraction in the rubber component, the total 1,2 defined as the sum of these values is calculated. -The vinyl bond content is preferably 3.5% or more.

The cis-1,4-bonding content of the cis-1,4-polybutadiene component is preferably 80% or more.

For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,4-bond content by the mass fraction in the rubber component, the total 1,4-defined as the sum of those values is calculated. The binding content is preferably 66.0% or more.

Although not intended to be bound by theory, the following can be considered as the mechanism by which the above effects are exerted. That is, isoprene-based rubber and cis-1,4-polybutadiene components as rubber components contain many double bonds in their main chains, but since such double bonds are affected by ozone, the main chain is liable to deteriorate. .. On the other hand, since the 1,2-polybutadiene component has few double bonds in the main chain, it has little effect on the main chain itself even when exposed to ozone, and is not easily deteriorated by ozone. In the present disclosure, each component is blended in a sidewall composed of a rubber composition containing carbon black in addition to the isoprene-based rubber, the rubber component containing the 1,2-polybutadiene component and the cis-1,4-polybutadiene component. By optimizing the amount and thickness of the sidewalls, it is considered that the effects of these are synergistically acting to achieve both ozone resistance and cut resistance. Further, by optimizing the thickness of the sidewall, it is possible to alleviate the initial strain of the tire provided with the sidewall and the strain when an input is input to the tire, so that it is considered that the cut resistance performance is further improved. , It is considered that it contributes to the manifestation of the above effect.

<Rubber component>
The rubber component of the present disclosure includes 20 to 50% by mass of isoprene-based rubber, 5% by mass or more of the 1,2-polybutadiene component, and 20% by mass or more of the cis-1,4-polybutadiene component. Among them, the rubber component of the present disclosure is preferably composed of an isoprene-based rubber, a 1,2-polybutadiene component, and a cis-1,4-polybutadiene component.

(Isoprene rubber)
As the isoprene-based rubber, for example, isoprene rubber (IR), natural rubber, and other rubbers commonly used in the rubber industry can be used. Of these, natural rubber is preferable from the viewpoint of improving cut resistance. Natural rubber includes non-modified natural rubber (NR), epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. Modified natural rubber (modified NR) such as rubber is also included, and all of them are preferably used, but non-modified natural rubber (NR) is more preferable. NR is also preferable from the viewpoint of excellent crack growth resistance. These isoprene-based rubbers can be used alone or in combination of two or more.

The NR is not particularly limited, and for example, those commonly used in the rubber industry such as SIR20, RSS # 3, and TSR20 can be used.

The cis-1,4-bond content of isoprene rubber is usually about 90 to 99% or about 93 to 98%. The cis-1,4-bond content of natural rubber is usually approximately 100%. When the cis-1,4-bond content of the isoprene-based rubber is within the above range, the effects of the present disclosure tend to be exhibited more satisfactorily. The cis-1,4-bond content in the present specification is a value measured by infrared absorption spectrum analysis.

The trans-1,4-bond content of the isoprene-based rubber is preferably 2.5% or less, more preferably 2.2% or less, still more preferably 2.0% or less. The lower limit of the trans-1,4-binding content may be, for example, 0% or 0.5% or more. The trans-1,4-bond content in the present specification is a value measured by infrared absorption spectrum analysis.

The 1,4-bonding content of the isoprene-based rubber is a value obtained by summing the measured values of the cis-1,4-bonding content and the trans-1,4-bonding content of the isoprene-based rubber.

The 1,2-vinyl bond content of the isoprene-based rubber is not particularly limited, but is preferably 1.8% or less, more preferably 1.3% or less, still more preferably 1.0% or less. The lower limit of the 1,2-vinyl bond content is not particularly limited. When the 1,2-vinyl bond content of the isoprene-based rubber is within the above range, the effects of the present disclosure tend to be exhibited more satisfactorily. The 1,2-vinyl bond content in the present specification is a value measured by infrared absorption spectrum analysis.

The content of the isoprene-based rubber in the rubber component is 20 to 50% by mass. If it is less than 20% by mass, sufficient cut resistance tends not to be obtained. On the other hand, if it exceeds 50% by mass, sufficient ozone resistance tends not to be obtained. The content is preferably 24% by mass or more, more preferably 27% by mass or more, and further preferably 30% by mass or more. The content is preferably 46% by mass or less, more preferably 43% by mass or less, and even more preferably 40% by mass or less. When the content of the isoprene-based rubber is within the above range, the effect of achieving both ozone resistance and cut resistance in a well-balanced manner can be obtained.

(1,2-polybutadiene component)
The 1,2-polybutadiene component refers to polybutadiene having a 1,2-vinyl bond content of more than 50% in the main chain. In the present disclosure, the "1,2-polybutadiene component" refers to one having a 1,2-vinyl bond content of preferably 70% or more. Further, it is usually called "1,2-polybutadiene" or the like. The 1,2-vinyl bond content is more preferably 80% or more, more preferably 90% or more, further preferably 94% or more, and may be 100%. The higher the 1,2-vinyl bond content, the less double bonds in the main chain and the better the ozone resistance.

The 1,4-bond content of the 1,2-polybutadiene component is preferably 30% or less, preferably 25% or less, more preferably 15% or less, still more preferably 5% or less. On the other hand, the lower limit of the 1,4-bond content is not particularly limited and may be 0%, or may be, for example, 1% or more, or 3% or more. When the 1,2-vinyl bond content and the 1,4-bond content of the 1,2-polybutadiene component are within the above ranges, the effect of improving the ozone resistance performance tends to be more satisfactorily exhibited.

The bonding mode (so-called microstructure) of the monomer unit in the 1,2-polybutadiene component includes 1,4-bond and 1,2-bond (1,2-vinyl bond). The 1,4-bonds are further divided into two types, a cis-1,4-bond having a cis structure and a trans-1,4-bond having a trans structure. As used herein, the term "1,4-binding content" means the sum of these cis-1,4-binding content and trans-1,4-binding content. The total content ratio of cis-1,4-bond, trans-1,4-bond and 1,2-vinyl bond in the microstructure is 100%. Therefore, the 1,4-bond content of the 1,2-polybutadiene component is naturally determined if the 1,2-vinyl bond content of the 1,2-polybutadiene component is determined according to the above. The 1,4-binding content can also be determined by summing the measured values of the cis-1,4-binding content and the trans-1,4-binding content, respectively.

The melting point of the 1,2-polybutadiene component is not particularly limited, but is preferably 50 to 150 ° C. The melting point is more preferably 60 ° C. or higher, more preferably 65 ° C. or higher, and even more preferably 70 ° C. or higher. Further, the melting point is more preferably 140 ° C. or lower, more preferably 135 ° C. or lower, and more preferably 130 ° C. or lower, from the viewpoint of molding processability and the viewpoint that the rubber composition can be prepared at a temperature at which thermal deterioration of the rubber component can be suppressed. More preferred. When the melting point of the 1,2-polybutadiene component is within the above range, the effect of improving the ozone resistance performance by blending the 1,2-polybutadiene component as a rubber component can be sufficiently exerted, and the effect of the present disclosure is further improved. There is a tendency to exert it. The melting point of the 1,2-polybutadiene component in the present specification is a value that can be measured according to ASTM D3418.

The crystallinity of the 1,2-polybutadiene component is not particularly limited, but is preferably 5 to 50%. Further, the crystallinity is more preferably 10% or more, more preferably 15% or more, still more preferably 18% or more from the viewpoint of crack growth resistance. Further, the crystallinity is more preferably 45% or less, more preferably 40% or less, from the viewpoint of suppressing the 1,2-polybutadiene component from becoming a resin-like physical property and satisfactorily exhibiting the properties as a rubber component. More preferably, 36% or less is further preferable. When the crystallinity of the 1,2-polybutadiene component is within the above range, the effect of improving the ozone resistance performance by blending the 1,2-polybutadiene component as the rubber component tends to be sufficiently exhibited.

The weight average molecular weight (Mw) of the 1,2-polybutadiene component is not particularly limited, but is preferably 50,000 or more, more preferably 70,000 or more, more preferably 100,000 or more, more preferably 150,000 or more, more preferably 170000 or more, and 190000. The above is more preferable, and 200,000 or more is further preferable. Further, the Mw is preferably 500,000 or less, more preferably 400,000 or less, more preferably 300,000 or less, still more preferably 270000 or less. When the Mw of the 1,2-polybutadiene component is within the above range, the effects of the present disclosure tend to be exhibited better. The weight average molecular weight (Mw) and the number average molecular weight (Mn) described later in the present specification are values that can be calculated as polystyrene-equivalent values measured by gel permeation chromatography (GPC).

The 1,2-polybutadiene component includes isotactic 1,2-polybutadiene, syndiotactic 1,2-polybutadiene and tactic 1,2-polybutadiene having different stereoregularities, and all of them can be used. Of these, syndiotactic 1,2-polybutadiene is preferable because the effects of the present disclosure can be more favorably exhibited. Syndiotactic 1,2-polybutadiene has a stereoregular structure in which side chain vinyl groups are alternately located on both sides of the polymer main chain.

The content of the 1,2-polybutadiene component in the rubber component is 5% by mass or more. If it is less than 5% by mass, sufficient ozone resistance tends not to be obtained. The content is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more. The content is preferably 40% by mass or less, more preferably 35% by mass or less, and further preferably 30% by mass or less. When the content of the 1,2-polybutadiene component is within the above range, the effect of achieving both ozone resistance and cut resistance in a well-balanced manner can be obtained.

As the 1,2-polybutadiene component, for example, those manufactured and sold by JSR Corporation and the like can be used. The 1,2-polybutadiene component can be used alone or in combination of two or more.

(Cis-1,4-polybutadiene component)
The cis-1,4-polybutadiene component refers to polybutadiene having a cis-1,4-bond content of more than 50% in the main chain. In the present disclosure, the "cis-1,4-polybutadiene component" refers to one having a cis-1,4-bonding content of preferably 80% or more. Further, it is usually called "HISIS butadiene rubber (HISIS BR)" or the like. The cis-1,4-binding content is more preferably 90% or more, more preferably 94% or more, still more preferably 97% or more. The upper limit of the cis-1,4-binding content is not particularly limited. When the cis-1,4-bond content of the cis-1,4-polybutadiene component is within the above range, the cut resistance tends to be excellent.

The trans-1,4-bond content of the cis-1,4-polybutadiene component is preferably 2.5% or less, more preferably 2.2% or less, still more preferably 2.0% or less. The lower limit of the trans-1,4-binding content is not particularly limited, but may be, for example, 0.5% or more.

The 1,4-bond content of the cis-1,4-polybutadiene component is the sum of the measured values of the cis-1,4-bond content and the trans-1,4-bond content of the cis-1,4-polybutadiene component, respectively. It is a value obtained by doing.

The 1,2-vinyl bond content of the cis-1,4-polybutadiene component is not particularly limited, but is preferably 1.8% or less, more preferably 1.3% or less, still more preferably 1.0% or less. The lower limit of the 1,2-vinyl bond content is not particularly limited. When the 1,2-vinyl bond content of the cis-1,4-polybutadiene component is within the above range, the effects of the present disclosure tend to be exhibited more satisfactorily.

_{The Mooney viscosity (Mooney viscosity ML 1 + 4} (100 ° C.)) measured at 100 ° C. of the cis-1,4-polybutadiene component is not particularly limited, but is preferably 35 or more, more preferably 37 or more, and further 40 or more. preferable. The Mooney viscosity ML _{1 + 4} (100 ° C.) is preferably 75 or less, more preferably 65 or less, and even more preferably 55 or less. _{When the Mooney viscosity ML 1 + 4} (100 ° C.) of the cis-1,4-polybutadiene component is within the above range, the effects of the present disclosure tend to be exhibited better. The Mooney viscosity ML _{1 + 4} (100 ° C.) in the present specification is a value that can be measured according to ISO289 and JIS K 6300.

The weight average molecular weight (Mw) / number average molecular weight (Mn) of the cis-1,4-polybutadiene component is not particularly limited, but is preferably 3.0 or less, more preferably 2.9 or less, and further preferably 2.8 or less. preferable. The Mw / Mn is preferably 1.9 or more, more preferably 2.0 or more. When the Mw / Mn of the cis-1,4-polybutadiene component is within the above range, the effects of the present disclosure tend to be exhibited more satisfactorily.

As the cis-1,4-polybutadiene component, a commercially available product or a synthetically obtained product may be used. As the commercially available product, for example, a product manufactured and sold by Ube Industries, Ltd., Zeon Corporation, JSR Corporation, Lanxess Corporation, or the like can be used. The synthesis method is not particularly limited, and those skilled in the art can easily prepare the cis-1,4-polybutadiene component so as to obtain the desired properties. For example, a method of synthesizing using a transition metal-based catalyst such as Ti, Co, or Ni, or a method of synthesizing using a rare earth element-based catalyst can be mentioned, and any of these methods is preferable.

As the rare earth element-based catalyst, known ones can be used, and examples thereof include a lanthanum series rare earth element compound, an organic aluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base, if necessary. Among them, lanthanum series rare earth element compounds are preferable from the viewpoint that BR having a high cis-1,4-bond content and a low 1,2-vinyl bond content can be obtained, and among them, a neodymium (Nd) -containing compound was used. Nd-based catalysts are preferred.

The content of the cis-1,4-polybutadiene component in the rubber component is 20% by mass or more. If it is less than 20% by mass, the ozone resistance and the cut resistance tend to be incompatible with each other. The content is preferably 25% by mass or more, more preferably 30% by mass or more, and further preferably 35% by mass or more. The content is preferably 80% by mass or less, more preferably 75% by mass or less, more preferably 70% by mass or less, more preferably 65% by mass or less, more preferably 60% by mass or less, and 55% by mass or less. Is even more preferable. When the content of the cis-1,4-polybutadiene component is within the above range, the effect of achieving both ozone resistance and cut resistance in a well-balanced manner can be obtained.

The cis-1,4-polybutadiene component can be used alone or in combination of two or more.

(Other rubber components)
The rubber component in the rubber composition may contain a rubber component (other rubber component) other than the above-mentioned isoprene-based rubber, 1,2-polybutadiene component and cis-1,4-polybutadiene component. Such other rubber components are not particularly limited, and conventional rubber industries such as isoprene-based rubbers, diene-based rubbers other than the above-mentioned isoprene-based rubbers, 1,2-polybutadiene components and cis-1,4-polybutadiene components, and butyl-based rubbers have been used. Any of the materials used can be preferably used. Examples of the diene rubber include styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Examples of the butyl rubber include butyl rubber (IIR), brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), and halogenated butyl rubber containing fluorinated butyl rubber (F-IIR). These rubber components can be used alone or in combination of two or more. Of these, SBR is preferable from the viewpoint of improving the physical characteristics of rubber such as fuel efficiency and wear resistance.

The styrene-butadiene rubber (SBR) is not particularly limited, and for example, unmodified emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), and modified emulsion-polymerized styrene-butadiene rubber obtained by modifying these. Examples thereof include modified SBR (modified E-SBR) and modified solution-polymerized styrene-butadiene rubber (modified S-SBR). Examples of the modified SBR include modified SBR having a modified terminal and / or main chain, modified SBR (condensate, having a branched structure, etc.) coupled with tin, a silicon compound, or the like. Further, as the SBR, there are an oil-extending type in which the flexibility is adjusted by adding a spreading oil and a non-oil-extending type in which no extending oil is added, and both of them can be used. As the SBR, for example, those manufactured and sold by JSR Corporation, Asahi Kasei Chemicals Co., Ltd., Zeon Corporation, ZS Elastomer Co., Ltd. and the like can be used. These SBRs can be used alone or in combination of two or more.

The styrene content of SBR is not particularly limited, but is preferably 15.0% by mass to 40.0% by mass. The styrene content is more preferably 20.0% by mass or more from the viewpoint of rubber strength and grip performance. The styrene content is more preferably 30.0% by mass or less from the viewpoint of fuel efficiency and wear resistance. The styrene content of SBR in the present specification is a value expressed as a mass fraction with respect to the entire polymer, and is a value ^{calculated by 1 1} H-NMR measurement.

The 1,2-vinyl bond content of SBR is not particularly limited, but is preferably 10.0 to 80.0%. The 1,2-vinyl bond content is more preferably 25.0% or more, further preferably 40.0% or more, from the viewpoint of ozone resistance, rubber strength and grip performance. Further, the 1,2-vinyl bond content is more preferably 75.0% or less, still more preferably 70.0% or less, from the viewpoint of fuel efficiency. When the 1,2-vinyl bond content of SBR is within the above range, the effects of the present disclosure tend to be exhibited better. The 1,2-vinyl bond content of SBR is a value expressed as a molar fraction of SBR with respect to the butadiene component.

The cis-1,4-binding content of SBR is not particularly limited, but is preferably 1% or more, and more preferably 5% or more. The cis-1,4-binding content is preferably 60% or less, more preferably 40% or less. The cis-1,4-bond content of SBR is a value expressed as a molar fraction of SBR with respect to the butadiene component.

When SBR is contained, the content in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more. The SBR content is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the content of SBR is within the above range, the effects of the present disclosure tend to be exhibited better. When an oil spread type SBR is used as the SBR, the content of the SBR itself as a solid content contained in the oil spread type SBR is defined as the content of the SBR in the rubber component.

(Total 1,2-vinyl bond content)
For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,2-vinyl bond content by the mass fraction in the rubber component, the total 1,2 defined as the sum of these values is calculated. The −vinyl bond content (also simply referred to as “total 1,2-vinyl bond content” in the present disclosure) is preferably 3.5% or more. The total 1,2-vinyl bond content is preferably 4.0% or more, more preferably 4.5% or more, still more preferably 5.0% or more. The total 1,2-vinyl bond content is preferably 40.0% or less, more preferably 35.0% or less, and even more preferably 30.0% or less. When the total 1,2-vinyl bond content is within the above range, the effect of achieving both ozone resistance and cut resistance tends to be more exhibited. Here, the total 1,2-vinyl bond content can be determined by Σ (mass fraction of each rubber component in the total rubber components × 1,2-vinyl bond content of each rubber component). For example, the rubber component is NR (1,2-vinyl bond content 0%) 50% by mass, 1,2-polybutadiene component (1,2-vinyl bond content 90%) 30% by mass, and cis-1,4-polybutadiene. When the component (1,2-vinyl bond content 1%) consists of 20% by mass, the total 1,2-vinyl bond content is 27.2% (= 50/100 × 0 + 30/100 × 90 + 20/100 × 1). be.

(Total 1,4-bond content)
For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,4-bond content by the mass fraction in the rubber component, the total 1,4-defined as the sum of those values is calculated. The binding content (also simply referred to as “total 1,4-binding content” in the present disclosure) is preferably 66.0% or more. The total 1,4-bond content is preferably 70.0% or more, more preferably 80.0% or more, still more preferably 90.0% or more. The total 1,4-bond content is preferably 98.0% or less, more preferably 97.0% or less, more preferably 96.0% or less, still more preferably 95.0% or less. When the total 1,4-bond content is within the above range, the ratio of the total 1,4-bond content and the total 1,2-vinyl bond content is optimized, and both ozone resistance and cut resistance can be balanced. Tend. Here, the total 1,4-bonding content can be determined by Σ (mass fraction of each rubber component in the total rubber component × 1,4-bonding content of each rubber component). For example, the rubber component is NR (1,4-bond content 100%) 50% by mass, 1,2-polybutadiene component (1,4-bond content 10%) 30% by mass, and cis-1,4-polybutadiene component (1,4-polybutadiene component). When it is composed of 1,4-bond content 99%) 20% by mass, the total 1,4-bond content is 72.8% (= 50/100 × 100 + 30/100 × 10 + 20/100 × 99).

<Carbon black>
The carbon black is not particularly limited, and general carbon blacks such as GPF, FEF, HAF, ISAF, and SAF can be used in the rubber industry. Carbon black is manufactured and sold by, for example, Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nittetsu Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. Things can be used. These carbon blacks can be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ ^{SA) of carbon black is not particularly limited, but is preferably 30 m 2} / g or more, more preferably 35 m ² / g or more, from the viewpoint of obtaining sufficient reinforcing property and good wear resistance. Preferably, 40 m ² / g or more is more preferable, 50 m ² / g or more is more preferable, and 80 m ² / g or more is further preferable. Further, the N ₂ ^{SA is preferably 300 m 2} / g or ^{less, more preferably 200 m 2} / g or less, still more preferably 150 m ² / g or less, from the viewpoint of excellent dispersibility and less heat generation. _{The N 2} SA of carbon black in the present specification is a value measured in accordance with JIS K 6217-2: 2001.

The amount of dibutyl phthalate (DBP) absorbed by carbon black is not particularly limited, but is 50 ml / 100 g or more from the viewpoint of obtaining sufficient reinforcing properties, good fuel efficiency, wet grip performance, and wear resistance. Is more preferable, 70 ml / 100 g or more is more preferable, 90 ml / 100 g or more is more preferable, and 115 ml / 100 g or more is further preferable. The amount of DBP absorbed is preferably 220 ml / 100 g or less, more preferably 180 ml / 100 g or less, and even more preferably 130 ml / 100 g or less from the viewpoint of fuel efficiency. The amount of DBP absorbed by carbon black in the present specification is a value measured according to JIS K 6217-4: 2008.

The content of carbon black with respect to 100 parts by mass of the rubber component is 50 parts by mass or more. If it is less than 50 parts by mass, it tends to be difficult to sufficiently exert the effect of achieving both ozone resistance and cut resistance. The content is preferably 52 parts by mass or more, more preferably 53 parts by mass or more, and further preferably 55 parts by mass or more. The content is preferably 150 parts by mass or less, more preferably 110 parts by mass or less, and further preferably 80 parts by mass or less. When the content of carbon black is within the above range, sufficient reinforcing property, good dispersion in rubber can be obtained, sufficient rubber strength, crack growth resistance tends to be obtained, and the light of rubber due to the light blocking effect. Oxidation tends to be suppressed, and the effects of the present disclosure can be better exerted.

<Other ingredients>
In addition to the above-mentioned components, the rubber composition of the present disclosure includes other components generally used in the production of rubber compositions, such as fillers other than carbon black (other fillers), silane coupling agents, oils, and the like. A resin, stearic acid, zinc oxide, an antioxidant, a wax, a processing aid, a vulcanizing agent, a vulcanization accelerator and the like can be appropriately contained.

(Other fillers)
As the filler, other fillers may be used in addition to carbon black. The filler is not particularly limited, and any filler commonly used in this field such as silica, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, and clay may be used. Can be done. These fillers can be used alone or in combination of two or more. When a filler other than carbon black is used as the filler, silica is preferable from the viewpoint of fuel efficiency, wet grip performance and reinforcing effect.

The silica is not particularly limited, and examples thereof include silica prepared by a dry method (silicic anhydride) and silica prepared by a wet method (hydrous silicic acid). Of these, silica prepared by a wet method is preferable because it has many silanol groups on the surface and many reaction points with the silane coupling agent. As the silica, for example, those manufactured and sold by Evonik Degussa, Solvay, Tosoh Silica Co., Ltd., Tokuyama Corporation and the like can be used. These silicas can be used alone or in combination of two or more.

The N ₂ ^{SA of silica is not particularly limited, but is preferably 80 m 2} / g or more, more preferably 110 m ² / g or more, and more preferably 140 m ² / g or more from the viewpoint of ensuring low fuel consumption and sufficient reinforcing properties. It is preferably 170 m ² / g or more, more preferably 170 m 2 / g or more. Further, the N ₂ SA is silica dispersibility, in view of workability, preferably 500 meters ² / g or less, more preferably 400 meters ² / g or less, more preferably ^{300m 2 / g, 200m 2 /} g or less Is even more preferable. The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

When silica is contained, the content of the rubber component with respect to 100 parts by mass is not particularly limited, but is preferably 5 parts by mass or more, preferably 10 parts by mass or more, from the viewpoint of ensuring low fuel consumption, wet grip performance and sufficient reinforcing properties. Is more preferable, and 30 parts by mass or more is further preferable. The content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 110 parts by mass or less, from the viewpoint of silica dispersibility, processability, and wet grip performance.

(Silane coupling agent)
When silica is contained, it is preferable to use it in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. Examples of such a silane coupling agent include a silane coupling agent having a sulfide group such as bis (3-triethoxysilylpropyl) disulfide and bis (3-triethoxysilylpropyl) tetrasulfide; 3-mercaptopropyltri. A silane coupling agent having a mercapto group such as methoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; 3-octanoylthio-1-propyltriethoxysilane, 3- Silane coupling agent having a thioester group such as hexanoylthio-1-propyltriethoxysilane and 3-octanoylthio-1-propyltrimethoxysilane; silane coupling having a vinyl group such as vinyltriethoxysilane and vinyltrimethoxysilane. Agent; silane coupling agent having an amino group such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane; γ-glycidoxypropyltriethoxy. Glycydoxy-based silane coupling agents such as silane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; 3-chloropropyl Examples thereof include chloro-based silane coupling agents such as trimethoxysilane and 3-chloropropyltriethoxysilane. Of these, sulfide-based and mercapto-based are preferable because they have a strong bond with silica and are excellent in fuel efficiency. It is also preferable to use a mercapto system from the viewpoint that fuel efficiency and wear resistance can be suitably improved. As such a silane coupling agent, for example, those manufactured and sold by Momentive, Evonik Degussa, etc. can be used. These silane coupling agents can be used alone or in combination of two or more.

The content of the silane coupling agent with respect to 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and 4.0 parts by mass because a sufficient silica dispersion effect can be obtained. The above is more preferable, and 6.0 parts by mass or more is further preferable. Further, the content is preferably 20.0 parts by mass or less, more preferably 18.0 parts by mass or less, for the reason that a sufficient coupling effect and silica dispersion effect are efficiently obtained to secure the reinforcing property. More preferably, it is 15.0 parts by mass or less.

(oil)
The oil is not particularly limited, and any oil usually used in the rubber industry can be preferably used, and examples thereof include process oils such as paraffin-based, aromatic-based, and naphthenic-based process oils. In addition, as an environmental measure, process oils having a low content of polycyclic aromatic compounds (PCA) compounds can be mentioned. Low PCA content process oils include Treated Distillate Aromatic Extract (TDAE), which is a re-extracted aromatic process oil, aroma substitute oil, which is a mixture of asphalt and naphthenic oil, and mild extraction solutions (MES). ), And heavy naphthenic oils and the like. Of these, aromatic process oils are preferable, and TDAE oils are more preferable. As the oil, for example, oil manufactured and sold by H & R, JXTG Energy Co., Ltd., Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., etc. can be used. These oils can be used alone or in combination of two or more.

The content of the rubber component with respect to 100 parts by mass when the oil is contained is not particularly limited, but is more preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. Further, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less from the viewpoint of ensuring the effect of improving the ozone resistance performance. When the oil content is within the above range, the effects of plasticizing the rubber and improving the dispersion of carbon black tend to be sufficiently obtained, and the effects of the present disclosure tend to be exhibited more satisfactorily. The oil content also includes the amount of oil used in oil spreading and oil treatment.

(resin)
The resin is not particularly limited, and a resin commonly used in conventional rubber compositions for tires such as aromatic petroleum resin can be used. Examples of the aromatic petroleum resin include phenolic resin, Kumaron inden resin, styrene resin, terpene resin, acrylic resin, rosin resin, dicyclopentadiene resin (DCPD resin) and the like. Examples of phenol-based resins include those manufactured by BASF and Taoka Chemical Industry Co., Ltd., and Kumaron Inden resins include those manufactured by Nittetsu Chemical & Materials Co., Ltd. and JXTG Energy Co., Ltd. As the styrene-based resin, for example, one manufactured by Arizona Chemical Co., Ltd. can be used. As the terpene resin, for example, those manufactured by Arizona Chemical Co., Ltd., Yasuhara Chemical Co., Ltd., and the like can be used. As the rosin-based resin, for example, those manufactured by Harima Chemicals Co., Ltd., Arakawa Chemicals Co., Ltd., and the like can be used. These resins can be used alone or in combination of two or more.

When the resin is contained, the content of the rubber component with respect to 100 parts by mass 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. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less. When the content of the resin is within the above range, the effects of the present disclosure tend to be exhibited better.

(stearic acid)
When stearic acid is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more from the viewpoint of processability. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of the vulcanization rate.

(Zinc oxide)
When zinc oxide is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more from the viewpoint of processability. The content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of wear resistance.

(Anti-aging agent)
The anti-aging agent is not particularly limited, and any of those usually used in the rubber industry can be preferably used. For example, a quinoline-based anti-aging agent, a quinone-based anti-aging agent, a phenol-based anti-aging agent, and phenylene. Examples thereof include a diamine-based antiaging agent and a carbamic acid metal salt. Of these, a phenylenediamine-based antiaging agent is preferable because it can better exert the effect of improving ozone resistance. Examples of the phenylenediamine-based anti-aging agent include N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (6PPD). ), N, N'-diphenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N, N'-bis (1-Methylheptyl) -p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-bis (1-ethyl-3-methylpentyl) -p -Phenylenediamine, N-4-methyl-2-pentyl-N'-phenyl-p-phenylenediamine, N, N'-diaryl-p-phenylenediamine, hindereddiaryl-p-phenylenediamine, phenylhexyl-p- Examples thereof include phenylenediamine and phenyloctyl-p-phenylenediamine. Among them, N- (1,3-) is excellent because it has an appropriate solubility in rubber and can improve ozone resistance deterioration, ultraviolet ray resistance deterioration, bending crack resistance and oxidation resistance deterioration from the rubber surface to the inside in a well-balanced manner. Dimethylbutyl) -N'-phenyl-p-phenylenediamine (6PPD) is more preferred. As the anti-aging agent, for example, those manufactured and sold by Ouchi Shinko Chemical Industry Co., Ltd., Kawaguchi Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd. and the like can be used. These anti-aging agents can be used alone or in combination of two or more.

When the anti-aging agent is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and further preferably 1.0 part by mass or more. The content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, and further preferably 3.0 parts by mass or less. When the content of the anti-aging agent is within the above range, the anti-aging effect can be sufficiently obtained and the discoloration due to the precipitation of the anti-aging agent on the tire surface tends to be suppressed.

(wax)
In the present disclosure, it is preferable to use an antiaging agent and a wax together because it can effectively prevent sunlight cracks and ozone cracks. The wax is not particularly limited, and any wax usually used in the rubber industry can be preferably used, and examples thereof include petroleum-based wax, mineral-based wax, and synthetic wax. Of these, petroleum wax is preferable. Examples of the petroleum-based wax include paraffin wax, microcrystalline wax, selected special waxes thereof, and the like, and among them, microcrystalline selected special wax is preferable. As the wax, for example, those manufactured and sold by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd. and the like can be used. These waxes can be used alone or in combination of two or more.

When wax is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.3 parts by mass or more, more preferably 0.7 parts by mass or more, and further preferably 0.8 parts by mass or more. The content is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2.0 parts by mass or less. When the wax content is within the above range, the effect of improving the ozone resistance performance can be more exerted, and the effect of the present disclosure tends to be more effectively exerted.

(Processing aid)
Examples of the processing aid include fatty acid metal salts, fatty acid amides, amide esters, silica surface activators, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. Of these, fatty acid metal salts are preferable. As the processing aid, for example, one manufactured by Structor can be used. These processing aids can be used alone or in combination of two or more.

When the processing aid is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and further preferably 1.0 part by mass or more. The content of the processing aid is preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, and further preferably 6.0 parts by mass or less. When the content of the processing aid is within the above range, the effects of the present disclosure tend to be exhibited better.

(Vulcanizing agent)
The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used, and examples thereof include organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, and metal oxides such as magnesium oxide. Be done. Of these, a sulfur-based vulcanizing agent is preferable. As the sulfur-based vulcanizing agent, for example, a sulfur donor such as sulfur or morpholine disulfide can be used. Among these, it is preferable to use sulfur. These vulcanizing agents can be used alone or in combination of two or more.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with dispersant, master batch type sulfur, etc.), and insoluble sulfur (oil-treated insoluble sulfur, etc.). However, all of them are preferably used. Of these, powdered sulfur is preferable. Sulfur is manufactured and sold by, for example, Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. Can be used.

When the vulcanizing agent is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and more preferably 1.5 parts by mass or more. The content is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, and further preferably 4.0 parts by mass or less. When the content of the vulcanizing agent is within the above range, an appropriate reinforcing effect tends to be obtained, and the effect of the present disclosure tends to be exhibited more satisfactorily. The sulfur content when sulfur is used as the vulcanizing agent means the content of the sulfur component itself contained in the oil-treated sulfur or the like when a component other than sulfur such as oil-treated sulfur is used. ..

(Vulcanization accelerator)
The vulcanization accelerator is not particularly limited, and known vulcanization accelerators can be used, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, and aldehyde-amine. Examples thereof include system or aldehyde-ammonia type, imidazoline type, and xantate type vulcanization accelerator. Of these, sulfenamide-based, thiuram-based, and guanidine-based are preferable, and sulfenamide-based is more preferable. As the vulcanization accelerator, for example, those manufactured and sold by Ouchi Shinko Chemical Industry Co., Ltd., Sanshin Chemical Industry Co., Ltd. and the like can be used. These vulcanization accelerators can be used alone or in combination of two or more.

Examples of the sulfenamide-based vulcanization accelerator include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), N, N. '-Dicyclohexyl-2-benzothiazolyl sulfenamide (DZ) and the like can be mentioned. Of these, N-cyclohexyl-2-benzothiazolyl sulfeneamide (CBS) is preferable because the effects of the present disclosure can be more favorably exhibited.

Examples of the thiuram-based sulfide accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD).

Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine (DPG), dioltotrilguanidine, orthotrilbiguanidine and the like.

The content of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and further preferably 0.5 parts by mass or more. The content is preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less. When the content of the vulcanization accelerator is within the above range, the fracture strength and elongation tend to be ensured, and the effects of the present disclosure tend to be exhibited more satisfactorily.

<Tire>
The tire of the present disclosure is based on 100 parts by mass of a rubber component containing 20 to 50% by mass of isoprene rubber, 5% by mass or more of a 1,2-polybutadiene component, and 20% by mass or more of a cis-1,4-polybutadiene component. The tire is made of a rubber composition containing 50 parts by mass or more of carbon black, and has a sidewall having a thickness of 1.5 mm or more in the tire axial direction at the maximum width position of the tire.

Hereinafter, as an embodiment of the present disclosure, a tire will be described with reference to the drawings. FIG. 1 shows an example of a schematic partial cross-sectional view of the tire 1. In FIG. 1, the left-right direction is the axial direction of the tire 1. The tire 1 includes a tread 2, a sidewall 3, a clinch 4, a bead core 5, a carcass 6, a cord layer 7, and a bead apex 8. The tire 1 includes a pair of side surfaces 11, and the position where the distance between the side surfaces 11 in the axial direction is maximum is the tire maximum width position PW. LB indicates a virtual straight line extending in the axial direction through the tire maximum width position PW. The thickness of the sidewall in the tire axial direction at the maximum tire width position is represented by the portion E sandwiched between the two arrows. The thickness of the sidewall in the present specification is measured in a state where the tire is incorporated in a regular rim (not shown) and the tire is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire. As used herein, the term "regular rim" means a rim defined in the standard on which the tire relies. The "standard rim" in the JATTA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are regular rims. As used herein, the normal internal pressure means the internal pressure defined in the standard on which the tire relies. The "maximum air pressure" in the JATMA standard, the "maximum value" published in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal internal pressures.

The sidewall is made of the above-mentioned predetermined rubber composition, and has a thickness of 1.5 mm or more in the tire axial direction at the tire maximum width position. When the thickness is 1.5 mm or more, the cut resistance can be ensured by relaxing the initial strain of the tire and the strain when an input is applied to the tire. The thickness is more preferably 1.7 mm or more, more preferably 1.8 mm or more, and even more preferably 2.0 mm or more. The thickness is more preferably 3.0 mm or less, more preferably 2.7 mm or less, and further preferably 2.5 mm or less. By making the sidewall made of the above-mentioned predetermined rubber composition and setting the thickness within the above range, there is a tendency that an effect that both ozone resistance and cut resistance can be balanced can be obtained.

(Tire manufacturing method)
A tire having a predetermined sidewall made of the above rubber composition can be produced by a general method. For example, in a closed kneader such as a Banbury mixer or a kneader, or a known kneader used in a general rubber industry such as an open roll, among the above components, components other than the vulcanizing agent and the vulcanization accelerator can be used. After kneading (base kneading step), a vulcanizing agent and a vulcanization accelerator are added and further kneaded (finishing kneading step) to produce an unvulcanized rubber composition. Next, the unvulcanized rubber composition is extruded according to a predetermined sidewall shape so that the thickness of the sidewall in the tire axial direction at the tire maximum width position of the obtained tire is 1.5 mm or more. , By pasting together with other tire members on a tire molding machine and molding by a usual method, an unvulcanized tire is formed, and this unvulcanized tire is pressure vulcanized in a vulcanizer. , Tires can be manufactured. A remill (re-kneading step) may be performed between the base kneading step and the finishing kneading step.

The kneading conditions are not particularly limited, but for example, in the base kneading step, kneading is performed at a discharge temperature of 120 to 170 ° C. for 1 to 15 minutes, and in the re-kneading step, 1 to 15 is carried out at a discharge temperature of 120 to 170 ° C. Kneading for 1 minute, and in the finishing kneading step, a method of kneading at 70 to 110 ° C. for 1 to 10 minutes can be mentioned. The vulcanization conditions are not particularly limited, and examples thereof include a method of vulcanizing at 150 to 200 ° C. for 10 to 30 minutes.

The tire of the present disclosure may be a pneumatic tire or a non-pneumatic tire, but is preferably a pneumatic tire. In addition, the pneumatic tires can be used for various tires such as passenger car tires, truck / bus tires, two-wheeled vehicle tires, competition tires and other high-performance tires, winter tires and run flat tires, and in particular, passenger cars. It can be suitably used as a tire.

The present disclosure will be specifically described based on examples. The present disclosure is not limited to these examples.

<Various chemicals used in Examples and Comparative Examples>
NR: TSR20 (isoprene rubber, cis-1,4-bond content: 100% (1,4-bond content: 100%))
Sis-1,4-polybutadiene component: Ubepol BR150B (BR synthesized using Hicis BR, Co-based catalyst, cis-1,4-bond content: 97%, trans-1,4-bond content: 2% ( 1,4-bond content: 99%), 1,2-vinyl bond content: 1%, Mooney viscosity ML _{1 + 4} (100 ° C): 40, Mw / Mn: 2.78, obtained from Ube Industries, Ltd. Possible)
1,2-Polybutadiene component 1: RB810 (Syndiotactic 1,2-polybutadiene, 1,4-bond content: 10%, 1,2-vinyl bond content: 90%, melting point: 71 ° C, crystallinity: 18 %, Mw: 200,000, available from JSR Corporation)
1,2-Polybutadiene component 2: RB840 (Syndiotactic 1,2-polybutadiene, 1,4-bond content: 6%, 1,2-vinyl bond content: 94%, melting point: 126 ° C, crystallinity: 36 %, Mw: 200,000, available from JSR Corporation)
Carbon Black 1: Show Black N550 (FEF, N ₂ SA: 42m ² / g, DBP oil absorption: 115ml / 100g, available from Cabot Japan Co., Ltd.)
Carbon Black 2: Show Black N220 (ISAF, N ₂ SA: 111m ² / g, DBP oil absorption: 115ml / 100g, available from Cabot Japan Co., Ltd.)
Oil: VivaTec500 (TDAE oil, available from H & R)
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (6PPD), available from Sumitomo Chemical Co., Ltd.)
Wax: Sunnock N (available from Ouchi Shinko Kagaku Kogyo Co., Ltd.)
Stearic acid: Stearic acid "Tsubaki" (available from NOF CORPORATION)
Zinc oxide: 2 types of zinc oxide (available from Mitsui Mining & Smelting Co., Ltd.)
Sulfur: Powdered sulfur (available from Karuizawa Sulfur Co., Ltd.)
Vulcanization accelerator: Noxeller CZ (N-cyclohexyl-2-benzothiazolyl sulfeneamide (CBS), available from Ouchi Shinko Kagaku Kogyo Co., Ltd.)

Examples and Comparative Examples <Manufacturing of rubber compositions and tires>
According to the formulation shown in Table 1, chemicals other than sulfur and the vulcanization accelerator were kneaded for 5 minutes using a 1.7 L sealed Banbury mixer until the discharge temperature reached 170 ° C. to obtain a kneaded product. Further, the obtained kneaded product was kneaded again with the Banbury mixer at a discharge temperature of 150 ° C. for 4 minutes (remill). Next, using a twin-screw open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 ° C. to obtain an unvulcanized rubber composition.

The unvulcanized rubber composition obtained above is extruded into a sidewall shape by an extruder equipped with a base having a predetermined shape, and the unvulcanized rubber composition is bonded together with other tire members on the tire molding machine to obtain an unvulcanized tire. A test tire (size: 195 / 65R15) was manufactured by forming and press vulcanizing under the condition of 170 ° C. for 15 minutes.

<Evaluation>
The obtained test tires were evaluated as follows. The results are shown in Table 1. In Table 1, the "side wall thickness" means the thickness (mm) of the sidewall in the tire axial direction at the tire maximum width position where the distance between both side surfaces in the tire axial direction is maximum. In addition, since "total 1,4-bond content" and "total 1,2-vinyl bond content" are values rounded to the first decimal place, the total value of these may not be 100. ..

(Ozone resistance)
After running the test tire for 30,000 km in a control room at a temperature of 40 ° C. and an ozone concentration of 50 ppm in accordance with JIS K 6259 "Vulcanized rubber and thermoplastic rubber-How to determine ozone resistance", the surface of the sidewall The state of the crack was visually observed, and Comparative Example 1 was set as 100 and displayed as an index. The larger the value, the better the ozone resistance.

(Cut resistance)
Make four cut scratches with a circumference length of 2 mm and a depth of 1 mm at the tire maximum width position (the position where the distance between both sides in the tire axial direction is maximum) on the sidewall of the test tire, and use a drum tester. Under the conditions of a tire internal pressure of 850 kPa and a load of 37.5 kN, a 30,000 km drum was run at 40 km / h, the length of cut scratches after the drum run was measured, an average value was calculated, and Comparative Example 1 was set as 100 and displayed as an index. .. The larger the value, the lower the average value and the better the cut resistance.

The goal is to exceed the sum of the evaluations of Comparative Example 1 (= 200). From the results in Table 1, it can be seen that the tire provided with the sidewall of the example has both ozone resistance and cut resistance as compared with those of the comparative example.

1 Tire 2 Tread 2A Cap Tread 2B Base Tread 2W Wing 3 Sidewall 4 Clinch 5 Bead Core 6 Carcus 7 Cord Layer 8 Bead Apex 9 Belt 9A, 9B Belt Ply 10 Band 11 Side PW Tire Maximum Width Position LB Tire Maximum Width Position Virtual straight line extending in the tread axis E Thickness of the sidewall in the tire axial direction at the maximum tire width position

Claims (7)

With 20 to 50% by mass of isoprene rubber,
1,2-polybutadiene component 5% by mass or more,
With respect to 100 parts by mass of the rubber component containing 20% by mass or more of the cis-1,4-polybutadiene component.
Consists of a rubber composition containing 50 parts by mass or more of carbon black.
A tire having a sidewall having a thickness of 1.5 mm or more in the tire axial direction at the maximum width position of the tire. The tire according to claim 1, wherein the 1,2-polybutadiene component has a melting point of 50 to 150 ° C. The tire according to claim 1 or 2, wherein the 1,2-vinyl bond content of the 1,2-polybutadiene component is 70% or more. The tire according to any one of claims 1 to 3, wherein the crystallinity of the 1,2-polybutadiene component is 5 to 50%. For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,2-vinyl bond content by the mass fraction in the rubber component, the total 1,2 defined as the sum of these values is calculated. The tire according to any one of claims 1 to 4, wherein the vinyl bond content is 3.5% or more. The tire according to any one of claims 1 to 5, wherein the cis-1,4-bonding content of the cis-1,4-polybutadiene component is 80% or more. For each rubber component constituting the rubber component, when calculating a value obtained by multiplying the 1,4-bond content by the mass fraction in the rubber component, the total 1,4-defined as the sum of those values is calculated. The tire according to any one of claims 1 to 6, wherein the binding content is 66.0% or more.

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