JP2021031645A - Rubber composition, tire and rubber product - Google Patents

Abstract

To provide a rubber composition having good workability.SOLUTION: The rubber composition includes a diene rubber and as a resin, syndiotactic polybutadiene and a vinyl butadiene polymer. The amount of 1,2-bond of the syndiotactic polybutadiene is 80 mass% or more and the syndiotacticity in the 1,2-bond is 60% or more; and the vinyl butadiene polymer has 1,2-bond and the syndiotacticity in the 1,2-bond is less than 60%.SELECTED DRAWING: None

Description

The present invention relates to rubber compositions, tires and rubber products.

For example, as described in Patent Document 1, by blending syndiotactic polybutadiene with a rubber composition, crack growth resistance is improved in rubber products such as tires.

Japanese Unexamined Patent Publication No. 2014-109019

However, as examined by the present inventors, in the rubber composition containing syndiotactic polybutadiene, the workability deteriorates due to the increase in unvulcanized viscosity and the increase in elasticity associated with the crystal phase of syndiotactic polybutadiene. It turned out.

Therefore, an object of the present invention is to provide a rubber composition having good workability (workability when not vulcanized and workability after vulcanization).

Another object of the present invention is to provide a tire using the rubber composition.

Furthermore, an object of the present invention is to provide a rubber product using the rubber composition.

The rubber composition according to the present invention
Diene rubber and
The resin contains syndiotactic polybutadiene and vinyl butadiene polymer.
The amount of 1,2-bonding of the syndiotactic polybutadiene is 80% by mass or more, and the syndiotacticity of the 1,2-bonding is 60% or more.
The vinyl butadiene polymer is a rubber composition having a 1,2-bond and having a syndiotacticity at the 1,2-bond of less than 60%. As a result, the rubber composition according to the present invention has good workability.

In the rubber composition according to the present invention, the vinyl butadiene polymer preferably has a number average molecular weight of 1,000 to 50,000. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

In the rubber composition according to the present invention, it is preferable that the vinyl butadiene polymer is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the diene-based rubber. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

In the rubber composition according to the present invention, the amount of 1,2-bonds of the vinyl butadiene polymer is preferably 3 to 80% by mass. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

In the rubber composition according to the present invention, the molecular weight distribution (weight average molecular weight / number average molecular weight) of the vinyl butadiene polymer is preferably 2.0 or less.

The tire according to the present invention is a tire using any of the above rubber compositions.

The rubber product according to the present invention is a rubber product selected from the group consisting of a conveyor belt, an anti-vibration rubber, an anti-vibration rubber, a rubber crawler, a belt, a hose and a fender using any of the above rubber compositions. Is.

According to the present invention, it is possible to provide a rubber composition having good workability (workability when not vulcanized and workability after vulcanization). Further, according to the present invention, it is possible to provide a tire having good workability, cut resistance and wear resistance. Further, according to the present invention, it is possible to provide a rubber product having good workability, cut resistance and wear resistance.

Hereinafter, embodiments of the present invention will be described. These descriptions are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

In the present invention, two or more embodiments can be arbitrarily combined.

In the present invention, the term "syndiotacticity" means the proportion of syndiotactics (alternating absolute configurations of asymmetric carbons) in the 1,2-bonds of the polymer backbone.

In the present specification, the numerical range is intended to include the lower limit value and the upper limit value of the range unless otherwise specified. For example, 1,000 to 50,000 means 1,000 or more and 50,000 or less.

(Rubber composition)
The rubber composition according to the present invention
Diene rubber and
The resin contains syndiotactic polybutadiene and vinyl butadiene polymer.
The amount of 1,2-bonding of the syndiotactic polybutadiene is 80% by mass or more, and the syndiotacticity of the 1,2-bonding is 60% or more.
The vinyl butadiene polymer is a rubber composition having a 1,2-bond and having a syndiotacticity at the 1,2-bond of less than 60%.

Hereinafter, the diene-based rubber and the resin, which are essential components of the rubber composition of the present invention, and optional components will be described as examples.

<Diene rubber>
The rubber composition according to the present invention contains a diene-based rubber as a rubber component. As the diene-based rubber, a known diene-based rubber can be used.

Examples of the diene rubber include natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). ..

The BR includes, for example, a high cis BR having a cis-1,4 bond content of 90% or more in a 1,3-butadiene unit and a cis-1,4 bond content of 50% or less in a 1,3-butadiene unit. Butabis BR and the like can also be mentioned.

The diene-based rubber may be a modified diene-based rubber. Examples of the modified diene rubber include the modified diene rubber described in JP-A-2019-104888.

In the present invention, one type of diene rubber can be used alone or two or more types (for example, two or three types) can be used in combination.

In one embodiment, the diene rubber is one or more selected from the group consisting of NR, IR, BR and SBR. In another embodiment, the diene rubber is one or more selected from the group consisting of NR, IR and BR. In yet another embodiment, the diene rubber is one or more selected from the group consisting of NR, IR and SBR. In yet another embodiment, the diene rubber is one or more selected from the group consisting of NR and SBR. In yet another embodiment, the diene-based rubber is NR only. In yet another embodiment, the diene-based rubber is IR only. In yet another embodiment, the diene-based rubber is SBR only. In yet another embodiment, there are only two types of diene rubber, NR and SBR.

In one embodiment, the diene-based rubber does not include 1,4-butadiene rubber.

In one embodiment, the diene-based rubber is 50 parts by mass or more, 60 parts by mass or more, 70 parts or more selected from the group consisting of NR, IR, BR and SBR with respect to 100 parts by mass of the diene-based rubber. Includes parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, or 100 parts by mass. In one embodiment, the diene-based rubber is 100 parts by mass or less, 90 parts by mass or less, 80 parts or more, one or more selected from the group consisting of NR, IR, BR and SBR with respect to 100 parts by mass of the diene-based rubber. Includes parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass.

In another embodiment, the diene-based rubber is 50 parts by mass or more, 60 parts by mass or more, and 70 mass by mass of one or more selected from the group consisting of NR, IR, and BR with respect to 100 parts by mass of the diene-based rubber. Includes parts or more, 80 parts by mass or more, 90 parts by mass or more, or 100 parts by mass. In one embodiment, the diene-based rubber is 100 parts by mass or less, 90 parts by mass or less, and 80 parts by mass of one or more selected from the group consisting of NR, IR, and BR with respect to 100 parts by mass of the diene-based rubber. Hereinafter, it includes 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass.

In one embodiment, when the diene rubber is NR only (NR100%), a combination of NR and BR and a combination of NR and SBR, particularly on the sidewall portion and tread portion of the tire (for example, base rubber and cap rubber). A rubber composition can be preferably applied.

<Other rubber components>
The rubber composition according to the present invention may or may not contain a non-diene rubber other than the above-mentioned diene rubber. Examples of non-diene rubber include butyl rubber (IIR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber, silicone rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylic rubber, and epi. Examples include chlorohydrin rubber and fluorine rubber.

The non-diene rubber may be used alone or in combination of two or more.

<Resin>
The rubber composition according to the present invention contains syndiotactic polybutadiene and a vinyl butadiene polymer as resins.

-Syndiotactic polybutadiene The syndiotactic polybutadiene in the present invention (hereinafter, may be simply referred to as "SPB") has a 1,2-bond amount of 80% by mass or more of the syndiotactic polybutadiene. The syndiotacticity in 2-binding is 60% or more.

As a result of the study by the present inventors, the addition of SPB to the rubber composition causes large energy dissipation due to sacrificial fracture of the crystal phase of SPB under high strain and blunting of the crack tip shape. , It was found that rubber products such as tires have improved cut resistance, fatigue resistance and crack growth resistance.

The microstructure of SPB may be such that the amount of 1,2-bonds is 80% by mass or more, and in addition to 1,2-bonds, one or more of cis-1,4 bonds and trans-1,4 bonds. May have.

In one embodiment, the amount of 1,2-bonds of SPB (the amount of 1,2-bonds in the microstructure of SPB) is 80% by mass or more, 85% by mass or more, 90% by mass or more, 91% by mass or more. It is 92% by mass or more, 93% by mass or more, 94% by mass or more, or 95% by mass or more. In one embodiment, the amount of 1,2-bonding of SPB is 100% by weight or less, 95% by weight or less, 94% by weight or less, 93% by mass or less, 92% by mass or less, 91% by mass or less, 90% by mass or less. Or 85% by mass or less.

In one embodiment, the syndiotacticity in the 1,2-binding of SPB is 60% or higher, 65% or higher, 70% or higher, 75% or higher, 80% or higher, 85% or higher, 90% or higher, 95% or higher. Or 100%. In one embodiment, the syndiotacticity in the 1,2-binding of SPB is 100% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less or 65% or less. Is.

In the present invention, syndiotacticity in the amount and the 1,2-bond of SPB 1,2 bonds ^is determined by ¹ H and ¹³ C nuclear magnetic resonance (NMR) analysis. ¹³ C-NMR is measured at a solvent: tetrachloroethane d-2 and a temperature of 110 ° C. or higher.

In addition to 1,3-butadiene, SPB may be a copolymer obtained by copolymerizing a small amount of conjugated diene such as 1,3-pentadiene and 1-pentyl-1,3-butadiene, or 1,3. It may be a copolymer of −butadiene.

When the SPB contains a unit derived from a conjugated diene other than 1,3-butadiene, in one embodiment, the proportion of the unit derived from 1,3-butadiene in all the repeating units of SPB is 80% or more, 85% or more. 90% or more, 95% or more, 98% or more or 99% or more. In that case, in one embodiment, the proportion of 1,3-butadiene-derived units in all repeating units of SPB is 99% or less, 98% or less, 95% or less, 90% or less, or 85% or less. ..

In one embodiment, the melting point of SPB (hereinafter, _{may be simply referred to as "mp s} ") is 100 ° C. or higher, 105 ° C. or higher, 110 ° C. or higher, 115 ° C. or higher, 120 ° C. or higher, 130 ° C. or higher, 140 ° C. or higher. , 150 ° C or higher, 160 ° C or higher or 170 ° C or higher. In one embodiment, mp _s is 180 ° C or lower, 170 ° C or lower, 160 ° C or lower, 150 ° C or lower, 140 ° C or lower, 130 ° C or lower, 120 ° C or lower, 115 ° C or lower, 110 ° C or lower or 105 ° C or lower. ..

In the present invention, mp _s refers to the melting peak temperature of the DSC curve during the second scanning of differential scanning calorimetry (DSC). The DSC puts a sample of SPB in the DSC device, raises the temperature from room temperature to 200 ° C. in the first scan, raises the temperature from -100 ° C. to 200 ° C. in the second scan, and each temperature rise rate is 10 ° C. / Minute.

In one embodiment, the weight average molecular weight (Mw) of SPB is 50,000 or more, 100,000 or more, 110,000 or more, 120,000 or more, 130,000 or more, 140,000 or more, 150,000 or more. 160,000 or more, 170,000 or more, 180,000 or more, 190,000 or more, 200,000 or more, 300,000 or more, 400,000 or more, 500,000 or more or 600,000 or more. In one embodiment, the SPB Mw is 800,000 or less, 700,000 or less, 600,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, 200,000 or less, 190,000 or less, 180,000 or less, 170,000 or less, 160,000 or less, 150,000 or less, 140,000 or less, 130,000 or less, 120,000 or less, 110,000 or less or 100,000 or less.

In one embodiment, the number average molecular weight (Mn) of SPB is 50,000 or more, 100,000 or more, 110,000 or more, 120,000 or more, 130,000 or more, 140,000 or more, 150,000 or more. 160,000 or more, 170,000 or more, 180,000 or more, 190,000 or more, 200,000 or more, 300,000 or more, 400,000 or more, 500,000 or more or 600,000 or more. In one embodiment, the Mn of SPB is 800,000 or less, 700,000 or less, 600,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, 200,000 or less, 190,000 or less, 180,000 or less, 170,000 or less, 160,000 or less, 150,000 or less, 140,000 or less, 130,000 or less, 120,000 or less, 110,000 or less or 100,000 or less.

The method for measuring Mw and Mn of SPB is as follows:
Gel permeation chromatography (GPC): Measured by a differential refractometer as a detector by "HLC-8220 / HT" manufactured by Tosoh Corporation, and shown in polystyrene conversion using monodisperse polystyrene as a standard. The column is "GMHHR-H (S) HT" manufactured by Tosoh Corporation, the eluent is trichlorobenzene, and the measurement temperature is 140 ° C.

The SPB is, for example, JP-A-2006-063183, JP-A-2000-119324, JP-A-2004-528410, JP-A-2005-518467, JP-A-2005-527641, JP-A-2009-108330. By the polymerization method described in JP-A, JP-A-7-25212, JP-A-6-306207, JP-A-6-199103, JP-A-6-92108, JP-A-6-87975, etc. Can be prepared.

As the SPB, a commercially available product may be used. Commercially available SPBs include, for example, JSR RB® series such as JSR's JSR RB® 810, 820, 830, 840; Ube Industries' UBEPOL VCR® 412, 617, 450. , 800 and the like, such as the UBEPOL VCR® series.

The SPB may be used alone or in combination of two or more.

The blending amount of SPB in the rubber composition may be appropriately adjusted and is not particularly limited. For example, the blending amount of SPB is 2 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. In one embodiment, the amount of SPB to be blended is 2 parts by mass or more, 3 parts by mass or more, 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, and 20 parts by mass or more with respect to 100 parts by mass of the diene rubber. , 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, or 45 parts by mass or more. In one embodiment, the amount of SPB to be blended is 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, 30 parts by mass or less, and 25 parts by mass or less with respect to 100 parts by mass of the diene rubber. , 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less.

-Vinyl butadiene polymer The vinyl butadiene polymer in the present invention (hereinafter, may be simply referred to as "Vi-BR") has a 1,2-bond and has a syndiotacticity of 60% in the 1,2-bond. Is less than.

In the rubber composition of the present invention, Vi-BR works to improve the balance between workability (unvulcanized viscosity) and fracture characteristics. Although we do not want to be bound by theory, this is because Vi-BR is highly compatible with SPB, and Vi-BR softens the amorphous part of SPB, which is a property derived from the crystalline part of SPB. It is presumed that this is because the bulk viscosity of the rubber composition can be reduced while maintaining the above.

The microstructure of Vi-BR may have one or more of cis-1,4 bond and trans-1,4 bond in addition to 1,2-bond.

In one embodiment, the amount of 1,2-bonds of Vi-BR (the amount of 1,2-bonds in the microstructure of Vi-BR) is 3% by mass or more, 5% by mass or more, 10% by mass or more, 20. Mass% or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70 It is mass% or more, 75 mass% or more, or 80 mass% or more. In one embodiment, the amount of 1,2-bonding of Vi-BR is 80% by mass or less, 75% by mass or less, 70% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass. % Or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass % Or less or 5% by mass or less.

In the rubber composition according to the present invention, the amount of 1,2-bonds of the vinyl butadiene polymer is preferably 3 to 80% by mass. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

In one embodiment, the syndiotacticity in the 1,2-binding of Vi-BR is less than 60%, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25. % Or less, 20% or less, 15% or less, 10% or less, 5% or less, 3% or less, 1% or less, or about 0%. In one embodiment, the syndiotacticity in the 1,2-binding of Vi-BR is 1% or greater, 3% or greater, or 5% or greater.

In the present invention, syndiotacticity in the amount and the 1,2-bond of the 1,2-bond of Vi-BR ^is determined by ¹ H and ¹³ C nuclear magnetic resonance (NMR) analysis.

Vi-BR may be a copolymer obtained by copolymerizing a small amount of conjugated diene such as 1,3-pentadiene and 1-pentyl-1,3-butadiene in addition to 1,3-butadiene, or 1 , 3-butadiene homopolymer may be used.

When Vi-BR contains units derived from conjugated diene other than 1,3-butadiene, in one embodiment, the proportion of units derived from 1,3-butadiene in all repeating units of Vi-BR is 80% or more. 85% or more, 90% or more, 95% or more, 98% or more or 99% or more. In that case, in one embodiment, the proportion of 1,3-butadiene-derived units in all repeating units of Vi-BR is 99% or less, 98% or less, 95% or less, 90% or less, or 85% or less. Is.

The molecular weight of Vi-BR may be adjusted as appropriate. In one embodiment, the number average molecular weight (Mn) of Vi-BR is 1,000 or more, 3,000 or more, 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, 20,000 or more. 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, 45,000 or more, 50,000 or more, 60,000 or more, 70,000 or more, 80,000 or more, 90,000 Or more or 100,000 or more. In one embodiment, the Mn of Vi-BR is 100,000 or less, 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, 45,000 or less, 40,000 or less. Below, 35,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, 9,000 or less, 8,000 or less, 7,000 or less, 6,000 Hereinafter, it is 5,000 or less, 4,000 or less, 3,000 or less, or 2,000 or less.

In the rubber composition according to the present invention, the vinyl butadiene polymer preferably has a number average molecular weight of 1,000 to 50,000. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

In one embodiment, the Mw of Vi-BR is 1,000 or more, 3,000 or more, 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more. More than 30,000, more than 35,000, more than 40,000, more than 45,000, more than 50,000, more than 60,000, more than 70,000, more than 80,000, more than 90,000 or 100,000 That is all. In one embodiment, the Mw of Vi-BR is 100,000 or less, 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, 45,000 or less, 40,000 or less. Below, 35,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, 9,000 or less, 8,000 or less, 7,000 or less, 6,000 Hereinafter, it is 5,000 or less, 4,000 or less, 3,000 or less, or 2,000 or less.

The method for measuring Mw and Mn of Vi-BR is the same as the method for measuring SPB.

In one embodiment, the molecular weight distribution (Mw / Mn) of Vi-BR is 2.0 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1. It is 07 or less or 1.05 or less. In one embodiment, the Mw / Mn of Vi-BR is 1.00 or higher, 1.04 or higher, 1.05 or higher, 1.07 or higher, 1.1 or higher, 1.2 or higher, 1.3 or higher, 1 .4 or more or 1.5 or more.

Vi-BR can be prepared, for example, by the method described in WO 2011/045918A1 and the like.

As the Vi-BR, a commercially available product may be used. Examples of commercially available Vi-BR products include the Ricon series such as Cry Valley's Ricon 130, 131, 134, 142, 150, 152, 153, 154, 156, and 157.

Vi-BR may be used alone or in combination of two or more.

The blending amount of Vi-BR in the rubber composition may be appropriately adjusted and is not particularly limited. For example, the blending amount of Vi-BR is 1 to 50 parts by mass with respect to 100 parts by mass of diene rubber. In one embodiment, the blending amount of Vi-BR is 1 part by mass or more, 2 parts by mass or more, 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, and 20 parts by mass with respect to 100 parts by mass of the diene rubber. Parts or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more or 45 parts by mass or more. In one embodiment, the blending amount of Vi-BR is 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, 30 parts by mass or less, 25 parts by mass with respect to 100 parts by mass of the diene rubber. Parts or less, 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less.

In the rubber composition according to the present invention, it is preferable that the vinyl butadiene polymer is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the diene-based rubber. As a result, in addition to good workability, excellent crack growth resistance can also be obtained.

<Other ingredients>
In addition to the above-mentioned essential components, a known additive to be blended in the rubber composition may be appropriately blended in the rubber composition according to the present invention. Examples of such additives include fillers (for example, carbon black and silica), vulcanizing agents (crosslinking agents), vulcanization accelerators, vulcanization retarders, antioxidants, reinforcing agents, softeners, and vulcanization. Auxiliary agents, colorants, flame retardants, lubricants, foaming agents, plasticizers, processing aids, antioxidants, scorch inhibitors, UV inhibitors, antistatic agents, color inhibitors, process oils and the like. These may be used individually by 1 type or in combination of 2 or more type, respectively.

In the rubber composition according to the present invention, when process oil is used, the blending amount of the process oil is 20 parts by mass or less and 15 parts by mass with respect to 100 parts by mass of the diene-based rubber from the viewpoint of heat generation and wear resistance. It is preferably 10 parts by mass or less or 5 parts by mass or less. In the rubber composition according to the present invention, when process oil is used, the blending amount of the process oil is 1 part by mass or more with respect to 100 parts by mass of the diene-based rubber from the viewpoint of workability and crack growth resistance. It is preferably 5 parts by mass or more, 10 parts by mass or more, or 15 parts by mass or more.

The method for preparing the rubber composition according to the present invention is not particularly limited, and a known method can be used. For example, a diene rubber, a resin (SPB and Vi-BR), and an optional component such as a filler are added at the same time or in an arbitrary order, and a kneader such as a Banbury mixer, a roll, or an internal mixer is added. It is obtained by kneading with.

In the rubber composition according to the present invention, as described above, Vi-BR reduces the viscosity of the bulk of the rubber composition while maintaining the properties derived from the crystal portion of SPB, and has good workability.

<Vulcanized rubber composition>
Preferably, the rubber composition according to the present invention is vulcanized by the method described below to obtain a vulcanized rubber composition, whereby a high-strength vulcanized rubber composition is obtained, and its cut resistance and abrasion resistance are significantly improved. Can be improved.

-Method for producing a suitable vulcanized rubber composition A method for producing a suitable vulcanized rubber composition is as follows.
1A) A step of kneading NR, SPB and Vi-BR in a rubber composition at a _{temperature higher than mp s} by 10 to 100 ° C.; or 1B) Diene-based rubber other than NR and SPB in a rubber composition. At the time of kneading with Vi-BR, a step of kneading at a temperature 10 to 100 ° C. higher than _{mp s and a step of kneading.}
2) Includes a step of vulcanizing the unvulcanized rubber composition obtained from the kneading step at _{a temperature of mp s or higher.}

When the diene rubber is NR, a double network is formed depending on the kneading conditions and the vulcanization temperature conditions, and the crack growth resistance and the like are greatly improved. As used herein, the term "double network" refers to a structure in which a three-dimensional network of SPBs is immobilized in a diene-based rubber network in a vulcanized rubber composition.

When the diene rubber is a diene rubber other than NR, even if the kneading conditions and the vulcanization temperature conditions are the same as the double network formation conditions in NR, the double network is not always formed, but the reinforcing effect by adding SPB is obtained. can get.

· In the kneading step above 1A) Step (kneading step), the temperature at the time of kneading by a high temperature 10 ° C. or higher than mp _s, can highly is compatible with SPB containing a crystal phase in NR.

By setting the temperature during kneading to mp _s + 100 ° C. or lower in the above step 1A), thermal deterioration of the resin (SPB and Vi-BR) and NR is suitably prevented, and the cut resistance of the vulcanized rubber composition and the cut resistance and Abrasion resistance can be improved.

In the step 1B) (kneading step), one diene rubber other than NR may be selected alone, or two, three or more diene rubbers may be selected from the diene rubbers of the rubber composition described above.

In the present specification, the temperature at the time of kneading in the kneading step means the temperature of the masterbatch at the time when the masterbatch of the rubber composition is discharged from the kneading device, and in the masterbatch kneading, immediately after being discharged from the kneading device. The temperature measured by a temperature sensor or the like inside the masterbatch. However, if there is a means for measuring the temperature of the rubber composition in the kneading device, the temperature of the masterbatch at the time of discharge may be measured.

In the present specification, the masterbatch is a kneading step in which a vulcanization system such as a vulcanizing agent and a vulcanization accelerator is not blended, and a step of kneading a diene rubber component, SPB, and optionally Vi-BR. The obtained rubber mixture.

In one embodiment, the temperature during the kneading in the kneading step, mp _s from 10 ° C. or higher, mp _s from 12 ° C. or higher, mp _s from 15 ℃ or higher, mp _s from 20 ° C. or higher, 30 ° C. or higher than mp _s , mp _s from 40 ° C. or higher, mp _s from 50 ° C. or higher, mp _s than 60 ° C. or higher, mp _s from 70 ° C. or higher, high 90 ° C. or higher than 80 ° C. or higher, or mp _s from mp _s. In one embodiment, the kneading temperature in the kneading step is mp _s + 100 ° C or lower, mp _s + 90 ° C or lower, mp _s + 80 ° C or lower, mp _s + 70 ° C or lower, mp _s + 60 ° C or lower, mp _s + 50 ° C. Hereinafter, it is mp _s + 40 ° C. or lower, mp _s + 30 ° C. or lower, or mp _s + 20 ° C. or lower.

In one embodiment, in step 1A), a step of adding SPB to a mixture of NR or NR and Vi-BR is included.

In one embodiment, in step 1B), a step of adding SPB to a diene rubber other than NR or a mixture of a diene rubber other than NR and Vi-BR is included.

1A) SPB is highly compatible with NR by kneading in the step, and then vulcanized in the above specific temperature range, so that SPB becomes semi-phase soluble in NR and becomes a high-strength vulcanized rubber composition. It is presumed.

In the method for producing the vulcanized rubber composition, a kneader such as a Banbury mixer, a roll, or an internal mixer is preferably used.

-Vulcanization step In the above 2) step (vulcanization step), by setting the vulcanization temperature to mp _s or higher, it is possible to thermodynamically suppress the domain structure in which the SPB is in a crystalline state with the diene rubber. Furthermore, in order to form a double network, it is considered important to vulcanize at a temperature of _{mp s or higher.} By vulcanizing the obtained unvulcanized rubber composition at _{a temperature of mp s} or higher, SPB becomes semi-phase soluble in the rubber component and is immobilized as a network in the rubber component, whereby the vulcanized rubber This is because it is considered that the above-mentioned double network can be formed in the composition. However, this does not mean that no double network is formed when vulcanized at a temperature _{lower than mp s.} This _{is because even when vulcanized at a temperature lower than mp s} , a part of SPB can be melted to form a double network at least partially. For example, the vulcanization temperature is "mp _s- 15 ° C." It is considered that a double network can be formed at least in part even if it is more than or _{less than mp s.}

In the present specification, the temperature at the time of vulcanization in the vulcanization step means the maximum temperature reached by the progress of vulcanization from the start of vulcanization (usually, the set temperature of the vulcanization apparatus).

In one embodiment, the vulcanization temperature in the vulcanization step is mp _s or higher, mp _s + 5 ° C. or higher, mp _s + 10 ° C. or higher, or mp _s + 13 ° C. or higher. In one embodiment, the vulcanization temperature in the vulcanization step is mp _s + 15 ° C. or lower, mp _s + 13 ° C. or lower, mp _s + 10 ° C. or lower, or mp _s + 5 ° C. or lower.

As the vulcanization in the vulcanization step, a known vulcanization system can be used, and it may be a sulfur vulcanization system or a non-sulfur vulcanization system.

In the vulcanized rubber composition obtained from the steps 1A) and 2), the SPB network is fixed in the NR network, and a double network is formed in the vulcanized rubber composition.

In one embodiment of the vulcanized rubber composition obtained from steps 1B) and 2), a double network is formed in the vulcanized rubber composition.

(tire)
The tire according to the present invention is a tire using any of the above rubber compositions. As a result, the tire according to the present invention has good cut resistance and wear resistance.

The portion of the tire using the rubber composition or the vulcanized rubber composition is not particularly limited. The rubber composition or the vulcanized rubber composition can be suitably used for parts requiring high durability such as a tread portion (cap rubber, base rubber, etc.), a belt coating rubber, and a sidewall portion.

When manufacturing a tire, the tire may be manufactured by using the above rubber composition at a desired portion and applying the above-mentioned method for manufacturing a suitable vulcanized rubber composition.

(Rubber product)
The rubber product according to the present invention comprises a conveyor belt, anti-vibration rubber, anti-vibration rubber, rubber crawler, belt, hose and fender using any of the above rubber compositions (or vulcanized rubber compositions). It is a rubber product selected from the group. As a result, the tire according to the present invention has good cut resistance and wear resistance.

When producing a rubber product, the rubber product may be produced by using the above rubber composition at a desired portion and applying the above-mentioned method for producing a suitable vulcanized rubber composition.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for the purpose of exemplifying the present invention and do not limit the present invention in any way. In the examples, the blending amount means parts by mass unless otherwise specified.

The details of the materials used in the examples are as follows.
Natural rubber (NR): RSS # 1
Syndiotactic polybutadiene (SPB): "JSR RB (registered trademark) 840" manufactured by JSR Corporation, 1,2-bonding amount = 94% by mass, syndiotacticity = 68%, melting point = 122 ° C., Mw = 163, 000, Mn = 66,000
Vinyl Butadiene Polymer 1 (Vi-BR 1): Synthesized by the method described below, Syndiotacticity = less than 60% Vinyl Butadiene Polymer 2 (Vi-BR 2): Synthesized by the method described below, Syndiotacticity = Less than 60% Vinyl Butadiene Polymer 3 (Vi-BR 3): Synthesized by the method described below, Syndiotacticity = less than 60% Vinyl Butadiene Polymer 4 (Vi-BR 4): Synthesized by the method described below, Syndiotacticity = Less than 60% Vinyl Butadiene Polymer 5 (Vi-BR 5): Synthesized by the method described below, Syndiotacticity = less than 60% Vinyl Butadiene Polymer 6 (Vi-BR 6): Synthesized by the method described below, Syndiotacticity = Less than 60% Vinyl Butadiene Polymer 7 (Vi-BR 7): Synthesized by the method described below, Syndiotacticity = less than 60% Process oil: Petroleum hydrocarbon process oil, trade name "DAIANA PROCESS OIL NS-28" manufactured by Idemitsu Kosan Co., Ltd.
Carbon black: ISAF
Wax: Product name "Microcrystalline Wax" manufactured by Seiko Kagaku Co., Ltd.
Anti-aging agent (6C): N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, trade name "Nocrack (registered trademark) 6C" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Anti-aging agent (TMQ): 2,2,4-trimethyl-1,2-dihydroquinoline polymer, trade name "Nocrack (registered trademark) 224" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator: N- (cyclohexyl) -2-benzothiazolesulfenamide, trade name "Noxeller (registered trademark) CZ" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization retarder: Trade name "CTPI" manufactured by Toray Fine Chemicals, N-cyclohexylthiophthalimide

-Synthesis of Vi-BR 1 Vi-BR 1 was synthesized as follows. In a nitrogen atmosphere, at room temperature, add 76 g of cyclohexane to the polymerization bottle, add 6.11 mL of n-butyllithium hexane solution (1.57 mol / L) as the polymerization initiator to the polymerization bottle, and use 2,2-di (2,2-di) as the randomizer. 0.69 mL of a cyclohexane solution of 2-tetrahydrofuryl) propane (0.69 mol / L) and 124.0 g of a cyclohexane solution of 1,3-butadiene (24.2% by mass) were added in sequence. Then, the reaction was carried out in a water bath at 50 ° C. for 55 minutes using a rotary polymerization tank. After completion of the reaction, 5 mL of 2-propanol degassed with nitrogen was added to the polymerization bottle to obtain cement. The cement was then washed 3 times with an excess of 2-propanol and methanol mixed solvent (volume ratio 1: 1). Then, 1.0 mL of a 2-propanol solution (5% by mass) of 2,2'-methylene-bis (4-ethyl-6-t-butylphenol) was added as an antioxidant. Then, the mixture was allowed to stand in a vacuum dryer at 65 ° C. for 6 hours, and the residual solvent was distilled off to obtain 29 g of Vi-BR 1.

-Synthesis of Vi-BR 2 30 g of Vi-BR 2 was obtained by synthesizing in the same manner as Vi-BR 1 except that the following points were changed.
Amount of randomizer: 2.22 mL
Reaction time: 45 minutes

-Synthesis of Vi-BR 3 30 g of Vi-BR 3 was obtained by synthesizing in the same manner as Vi-BR 1 except that the following points were changed.
Amount of randomizer: 6.94 mL
Reaction temperature: 20 ° C
Reaction time: 45 minutes

-Synthesis of Vi-BR 4 30 g of Vi-BR 4 was obtained by synthesizing in the same manner as Vi-BR 1 except that the following points were changed.
Amount of Polymerization Initiator: 2.35 mL
Amount of randomizer: 0.27 mL
Reaction time: 70 minutes

-Synthesis of Vi-BR 5 29 g of Vi-BR 5 was obtained by synthesizing in the same manner as Vi-BR 1 except that the following points were changed.
Amount of Polymerization Initiator: 2.35 mL
Amount of randomizer: 0.85 mL
Reaction time: 60 minutes

-Synthesis of Vi-BR 6 30 g of Vi-BR 6 was obtained by synthesizing in the same manner as Vi-BR 1 except that the following points were changed.
Amount of Polymerization Initiator: 2.35 mL
Amount of randomizer: 2.67 mL
Reaction temperature: 20 ° C
Reaction time: 45 minutes

-Synthesis of Vi-BR 7 The reaction was carried out in the same manner as Vi-BR 1 except that the following points were changed to obtain cement.
Amount of cyclohexane: 67g
Amount of Polymerization Initiator: 1.70 mL
Amount of randomizer: 7.71 mL
Amount of 1,3-butadiene cyclohexane solution: 100.0 g
Reaction temperature: 20 ° C
Reaction time: 45 minutes Then the cement was poured into an excess amount of 2-propanol to give a white precipitate. In addition, the precipitate was washed twice with 2-propanol. Then, an antioxidant was added in the same manner as in Vi-BR 1, dried and the residual solvent was distilled off to obtain 24 g of Vi-BR 7.

Viscoelasticity measuring device: Product name "ARES-G2" manufactured by TA Instruments

In the examples, the amount of 1,2-bonding of SPB and Vi-BR and the syndiotacticity of the 1,2-bonding; Mn and Mw of Vi-BR were determined by the method described above.

(Examples 1 to 8, Comparative Examples 1 to 2 and Reference Examples 1 to 2)
The non-production kneading step was carried out with the formulations shown in Tables 1 and 2. The kneading temperature was 160 ° C. Next, the components shown in Table 1 were added to the master batch obtained from the non-production kneading step, and a production vulcanization step was performed to obtain a vulcanized rubber composition. The temperature during vulcanization was 160 ° C.

-Unvulcanized viscosity measurement test For each sample of each masterbatch obtained from the non-production kneading step, the unvulcanized viscosity was measured at a temperature of 80 ° C. in accordance with JIS K 630-1: 2013. The reciprocal of the measured value was taken, the value of Comparative Example 1 was set to 100, and the index was displayed. The results are shown in Table 2. The larger the index value, the smaller the unvulcanized viscosity and the better the workability.

Each sample of the vulcanized rubber composition obtained from the production vulcanization step was subjected to the elastic modulus test and the crack resistance test described below, respectively.

-Viscoelasticity test Each sample of vulcanized rubber composition is measured under the conditions of frequency 15 Hz, shear strain 10%, and temperature 50 ° C. using a viscoelasticity measuring device, and the shear elastic modulus G'(MPa) is measured. did. The reciprocal of the measured value was taken, the value of Comparative Example 1 was set to 100, and the index was displayed. The results are shown in Table 2. The larger the index value, the smaller the elastic modulus and the better the workability.

-Crack resistance test For each sample of vulcanized rubber composition, the tear strength was measured in a trough shape according to JIS K 6252 using a tensile test device. The measured value of Comparative Example 1 was set to 100, and the index was displayed. The results are shown in Table 2. The larger the index value, the larger the tear strength and the better the crack growth resistance.

As shown in Table 2, it can be seen that in the examples, the unvulcanized viscosity and the exponential values of the elastic modulus are large, and the workability is excellent.

Further, from the comparison of Examples 3, 6 and 7, it can be seen that the smaller the Mn of Vi-BR, the better the crack growth resistance tends to be.

Further, in Examples 1 to 7 in which the blending amount of Vi-BR was 10 parts by mass, the index value of the crack growth resistance was large, and it was found that the crack growth resistance was excellent in addition to the workability.

Furthermore, from the comparison of Examples 1, 2 and 3 and the comparison of Examples 4, 5 and 6, it can be seen that the smaller the 1,2-bonding amount of Vi-BR, the better the crack growth resistance tends to be. ..

According to the present invention, it is possible to provide a rubber composition having good workability. Further, according to the present invention, it is possible to provide a tire having good cut resistance and wear resistance. Further, according to the present invention, it is possible to provide a rubber product having good cut resistance and wear resistance.

Claims (7)

Diene rubber and
The resin contains syndiotactic polybutadiene and vinyl butadiene polymer.
The amount of 1,2-bonding of the syndiotactic polybutadiene is 80% by mass or more, and the syndiotacticity of the 1,2-bonding is 60% or more.
A rubber composition in which the vinyl butadiene polymer has a 1,2-bond and the syndiotacticity at the 1,2-bond is less than 60%. The rubber composition according to claim 1, wherein the vinyl butadiene polymer has a number average molecular weight of 1,000 to 50,000. The rubber composition according to claim 1 or 2, wherein the vinyl butadiene polymer is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the diene-based rubber. The rubber composition according to any one of claims 1 to 3, wherein the amount of 1,2-bonds of the vinyl butadiene polymer is 3 to 80% by mass. The rubber composition according to any one of claims 1 to 4, wherein the vinyl butadiene polymer has a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2.0 or less. A tire using the rubber composition according to any one of claims 1 to 5. A rubber selected from the group consisting of a conveyor belt, an anti-vibration rubber, an anti-vibration rubber, a rubber crawler, a belt, a hose and a fender, using the rubber composition according to any one of claims 1 to 5. Product.