JP2013241521A - Isoprene-butadiene copolymer, method of manufacturing isoprene-butadiene copolymer, rubber composition, and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an isoprene-butadiene copolymer of which the starting material is not a fossil resource; a method of manufacturing the isoprene-butadiene copolymer; a rubber composition using the isoprene-butadiene copolymer; and a tire using the rubber composition.SOLUTION: An isoprene-butadiene copolymer is formed by copolymerizing a bio-butadiene monomer and a bio-isoprene monomer synthesized from a resource derived from an organism including a plant resource, wherein a value of δ13C of a carbon atom derived from the bio-isoprene monomer is -30 per mill to -28.5 per mill, or at least -22 per mill, and a value of Δ14C of a carbon atom derived from the bio-butadiene monomer is -75 to -225 per mill.

Description

  The present invention uses an isoprene-butadiene copolymer not using fossil resources as a starting material, a method for producing an isoprene-butadiene copolymer, a rubber composition using the isoprene-butadiene copolymer, and the rubber composition. Regarding tires.

In recent years, a method for refining fuel oil from biological resources (so-called biomass) including plant resources has been proposed due to increasing demands for reducing fossil resource consumption and greenhouse gas emissions (patents) Reference 1). Such a fuel oil is called a biofuel, and since it does not increase the total amount of carbon dioxide emission, it is expected in the future as a substitute for a fuel oil derived from fossil resources.
On the other hand, many compounds derived from fossil resources are used not only in the field of fuel oil but also in the fields of home appliances, household goods, automobiles and the like.
As an example, by using isoprene-butadiene copolymer (BIR) or styrene-isoprene-butadiene copolymer (SIBR) as a material for automobile tires, a tire having excellent low rolling resistance and wear resistance is obtained. Therefore, it is useful for automobile tires (see Patent Documents 2 and 3). Isoprene and butadiene, which are raw materials for these tire materials, are also manufactured using fossil resources, especially petroleum resources. However, plants that are similarly renewable resources are also used due to problems such as depletion of petroleum resources and protection of the natural environment. There is a demand to use biological resources including resources as raw materials.

JP 2009-046661 A Japanese Patent Laid-Open No. 7-149841 JP-A-6-179730

  The present invention uses an isoprene-butadiene copolymer not using fossil resources as a starting material, a method for producing an isoprene-butadiene copolymer, a rubber composition using the isoprene-butadiene copolymer, and the rubber composition. The issue is to provide tires.

The present invention
1. An isoprene-butadiene copolymer obtained by copolymerizing a biobutadiene monomer and a bioisoprene monomer synthesized from biological resources including plant resources, the carbon atom derived from the bioisoprene monomer Isoprene having a δ13C value of −30 ‰ to −28.5 ‰, or −22 ‰ or more, and a Δ14C value of carbon atoms derived from the biobutadiene monomer of −75 to −225 ‰ Butadiene copolymer,
2. An isoprene-butadiene copolymer obtained by copolymerizing a biobutadiene monomer and a bioisoprene monomer synthesized from a biological resource including a plant resource, the carbon atom derived from the biobutadiene monomer ^An isoprene-butadiene copolymer having a ¹⁴ C decay per gram amount per minute of 0.1 dpm / gC or more,
3. The isoprene-butadiene copolymer according to 1 or 2 above, wherein the molecular weight of the isoprene-butadiene copolymer is 1000 to 5000000,
4). The isoprene-butadiene copolymer is an isoprene-butadiene-styrene copolymer obtained by copolymerizing a biobutadiene monomer synthesized from biological resources including plant resources, a bioisoprene monomer, and styrene. Isoprene-butadiene copolymer according to any one of 1 to 3,
5. Content of the structural unit derived from a bioisoprene monomer is 10-60 mass%, and content of the structural unit derived from a biobutadiene monomer is 40-90 mass% in any one of said 1-3. Isoprene-butadiene copolymer of
6). The content of the structural unit derived from the bioisoprene monomer is 5 to 40% by mass, the content of the structural unit derived from the biobutadiene monomer is 30 to 90% by mass, and the content of the structural unit derived from styrene The isoprene-butadiene copolymer according to 4 above, wherein the amount is 5 to 30% by mass;
7). A method for producing the isoprene-butadiene copolymer according to any one of 1 to 6 above, wherein a mixture containing a bioisoprene monomer and a biobutadiene monomer from a biological resource including a plant resource is produced. , A method for producing an isoprene-butadiene copolymer to be copolymerized using the mixture,
8). Bio-ethanol is synthesized from bio-derived resources including plant resources, and the bio-butadiene monomer is brought into contact with the composite metal oxide containing at least magnesium and silicon as metal elements under heating. A method for producing an isoprene-butadiene copolymer as described in 7 above, wherein an isoprene-butadiene copolymer is produced using the biobutadiene monomer.
9. Bioisoprene monomer synthesized from biological resources including plant resources is cultured in cells containing heterologous nucleic acid encoding isoprene / synthase / polypeptide under culture conditions suitable for isoprene production, and the culture The method for producing an isoprene-butadiene copolymer according to 7 or 8 above, wherein a isoprene-butadiene copolymer is produced using a bioisoprene monomer obtained by recovery from
10. A rubber composition comprising the isoprene-butadiene copolymer according to any one of 1 to 6 above,
11. A tire comprising the rubber composition according to 10 above,
I will provide a.

  According to the present invention, an isoprene-butadiene copolymer not using fossil resources as a starting material, a method for producing an isoprene-butadiene copolymer, a rubber composition using the isoprene-butadiene copolymer, and the rubber composition The used tire can be provided.

Hereinafter, the isoprene-butadiene copolymer according to the embodiment of the present invention will be described in detail.
[Isoprene-butadiene copolymer]
The isoprene-butadiene copolymer according to the embodiment of the present invention is a biobutadiene monomer synthesized from biological resources including plant resources and an isoprene-butadiene copolymer obtained by copolymerizing a bioisoprene monomer. The value of δ13C of carbon atoms derived from the bioisoprene monomer in the isoprene-butadiene copolymer is −30 ‰ to −28.5 ‰, or −22 ‰ or more, The value of Δ14C of carbon atoms derived from the butadiene monomer is −75 to −225 ‰. Here, the value of δ13C of the carbon atom derived from the bioisoprene monomer in the isoprene-butadiene copolymer is measured by a stable isotope ratio measuring device.

The δ13C of the carbon atom represents the ratio of stable isotopes in the substance. Δ13C carbon atoms, at the carbon atom in the substance of interest, ¹³ C and ^{12 13} C / ¹² C which is the ratio of the C is, peers in the standard sample (Cretaceous belemnitida (fossil arrows stone) s) It is an index that indicates how much it is deviated from the body ratio, and this ratio is represented by ‰ (percentage). It means that the ratio of ¹³ C in a substance is so low that the value (negative value) of (delta) ^13C leaves | separates from zero.
Light isotopes are more diffusive and more reactive than heavy isotopes. For example, in the case of carbon atoms of carbon dioxide in the atmosphere taken into plants by photosynthesis, ¹² C is better than ¹³ C. It has been found that it is easily fixed in plants.
That is, the carbon atoms taken into the plant body have a relatively large amount of ¹² C and a smaller amount of ¹³ C than carbon atoms in the atmosphere. Therefore, the stable isotope ratio (δ13C) of carbon taken into the plant body is lower than the stable isotope ratio of carbon existing in the atmosphere.
This change in isotope ratio is called isotope fractionation and is represented by Δ13C (Δ13C is distinguished from δ13C).
Δ13C = (δ13C in the atmosphere) − (δ13C in the sample)
Therefore, it is possible to specify the substance derived from the isoprene monomer used when the isoprene-butadiene copolymer is produced from the value of δ13C of carbon atoms derived from the isoprene monomer in the isoprene-butadiene copolymer. it can.

The value of Δ14C of carbon atoms derived from the biobutadiene monomer is ¹⁴ C when it is assumed that δ13C of carbon atoms derived from the biobutadiene monomer as the sample is −25.0 ‰. is a value converted to a concentration ⁽¹⁴ aN). The value of δ13C of carbon atoms derived from the biobutadiene monomer in the isoprene-butadiene copolymer was measured with a stable isotope ratio measuring device. Therefore, it means that the ratio of ¹⁴ C in a substance is so low that the value (negative value) of Δ14C of a carbon atom derived from a biobutadiene monomer is away from zero.
That is, the carbon atoms taken into the plant body have a relatively large amount of ¹² C and a smaller amount of ¹³ C than carbon atoms in the atmosphere. Therefore, the stable isotope ratio (δ13C) of carbon taken into the plant body is lower than the stable isotope ratio of carbon existing in the atmosphere.
This change in isotope ratio is called isotope fractionation and is represented by Δ13C (Δ13C is distinguished from δ13C).
Δ13C = (δ13C in the atmosphere) − (δ13C in the sample)
Δ14C can be calculated from the above-described value of δ13C as follows.
δ14C = [( ¹⁴ As− ¹⁴ AR) / ¹⁴ AR] × 1000 (1)
δ13C = [( ¹³ As− ¹³ APDB) / ¹³ APDB] × 1000 (2)
here,
¹⁴ As: ¹⁴ C concentration of sample carbon: ( ¹⁴ C / ¹² C) s or ( ¹⁴ C / ¹³ C) s
¹⁴ AR: ¹⁴ C concentration of standard modern carbon: ( ¹⁴ C / ¹² C) R or ( ¹⁴ C / ¹³ C) R
The ¹⁴ C concentration in the equation (1) is converted based on the following equation based on the measured value of δ13C.
^{14 AN = 14 As × (0.975} / (1 + δ13C / 1000)) 2 ( when using a ¹⁴ C / ¹² C as ¹⁴ As)
Or
^{14 AN = 14 As × (0.975} / (1 + δ13C / 1000)) ( when using ¹⁴ C / ¹³ C as ¹⁴ As)
From the above,
Δ14C = [( ¹⁴ AN− ¹⁴ AR) / ¹⁴ AR] × 1000 (‰) is calculated.

The value of Δ14C of carbon atoms derived from the biobutadiene monomer in the isoprene-butadiene copolymer is −75 to −225 ‰, which is the same level as Δ14C of carbon in carbon dioxide in the current atmosphere. And means carbon contained in organic matter fixed in the existing growing plant body.
Since the half-life of radioactive carbon ¹⁴ C is about 5730 years, the carbon contained in the fossil resource does not include radioactive carbon ¹⁴ C. The Δ14C of the butadiene monomer derived from fossil resources is about −1000 ‰.
Therefore, the Δ14C value of the carbon atom derived from the butadiene monomer in the isoprene-butadiene copolymer, or the amount of gram per minute of ¹⁴ C decay per minute, the value of δ13C, the butadiene unit amount in the isoprene-butadiene copolymer It is possible to specify whether the body-derived material is a fossil resource or a biological resource including plant resources (so-called biomass).
The molecular weight of the isoprene-butadiene copolymer of the present invention can be 1000 to 5000000. Preferably, it is 100,000 to 500,000, More preferably, it is 150,000 to 300,000.

In producing the isoprene-butadiene copolymer of the present invention, the butadiene monomer used is a butadiene monomer containing at least a biobutadiene monomer. It is preferable that 10-100 mass% of biobutadiene monomers are contained with respect to the mass.
The isoprene-butadiene copolymer of the present invention is obtained by copolymerizing an isoprene monomer containing at least a bioisoprene monomer and a butadiene monomer containing at least a biobutadiene monomer. Accordingly, an isoprene-butadiene-styrene copolymer obtained by copolymerization using a styrene monomer is included.

  The content of the monomer constituting the isoprene-butadiene copolymer of the present invention is such that the content of the structural unit derived from the bioisoprene monomer is 10 to 60% by mass, and the structural unit derived from the biobutadiene monomer. In the case of an isoprene-butadiene-styrene copolymer, the content of the structural unit derived from the bioisoprene monomer is preferably 5 to 40% by mass. In addition, it is desirable that the content of the structural unit derived from the biobutadiene monomer is 30 to 90% by mass and the content of the structural unit derived from styrene is 5 to 30% by mass. By setting the content of the structural unit derived from these monomers within the above range, appropriate physical properties can be obtained when a tire is obtained.

[Bioisoprene monomer component]
The bioisoprene monomer is obtained from biological resources including plant resources using microbial cells such as various fungi. A method for obtaining a bioisoprene monomer from biological resources including plant resources by using microorganisms such as various bacteria is known in, for example, Japanese Patent Application Publication No. 2011-526943 and Japanese Patent Application Publication No. 2011-505841. It has become. In these methods, cells containing a heterologous nucleic acid encoding isoprene / synthase / polypeptide are cultured under a culture condition suitable for isoprene production, and bioisoprene monomer is produced from the culture and recovered. is there. In these techniques, microbial cells derived from natural products that produce isoprene may be used as they are, or isoprene / synthase / polypeptide in the microbial cells may be transformed into Escherichia coli by genetic manipulation from the microbial cells derived from the natural products. Can be used as isoprene-producing bacteria.
As biological resources including plant resources, plant resources including cellulose and the like and various sugars such as glucose obtained from the plant resources can be used.

[Biobutadiene monomer component]
The biobutadiene monomer component is obtained by synthesizing bioethanol synthesized from biological resources including plant resources as a starting material.

<Method of synthesizing biobutadiene monomer>
A method for synthesizing a biobutadiene monomer using bioethanol synthesized from biological resources (biomass) including plant resources as a starting material will be described.
First, bioethanol is produced from biomass. The produced bioethanol is brought into contact with a composite metal oxide containing at least magnesium and silicon as metal elements under heating to produce a mixture containing a biobutadiene monomer component. A biobutadiene monomer component is extracted from this mixture, and a butadiene polymer is synthesized using the extracted biobutadiene monomer component.
In this synthesis method, the composite metal oxide acts as a catalyst. From the viewpoint of expressing good catalytic activity, the temperature when bioethanol is brought into contact with the composite metal oxide is preferably 350 ° C to 450 ° C.

(Production of bioethanol)
Examples of biological resources that can be used as raw materials for bioethanol include sugarcane, corn, sugar beet, cassava, beet, wood, and algae. Among these resources, it is preferable to use sugarcane, corn, and sugar beet that contain a large amount of sugar or starch from the viewpoint of production efficiency.

(Composite metal oxide)
The composite metal oxide contains at least magnesium and silicon as metal elements. Among these, it is preferable to use a silica-magnesia composite oxide synthesized by a sol-gel method. Usable metal elements include zinc, zirconium, copper, aluminum, calcium, phosphorus, tantalum and the like.

(Production method of composite metal oxide)
Examples of the method for producing the composite metal oxide include a sol-gel method and a method in which silica is mixed with an aqueous solution of a metal salt and supported by evaporation and drying.

(Contact reaction between bioethanol and mixed metal oxide)
For the contact reaction between the composite metal oxide and bioethanol, a generally known fixed bed gas flow-type catalytic reaction apparatus (for example, JP-A-2009-51760) can be used.
The composite metal oxide is filled in the reaction tube, heated as a pretreatment in a carrier gas atmosphere such as nitrogen gas, and then the temperature of the reaction tube is lowered to the reaction temperature. Thereafter, a predetermined amount of carrier gas and bioethanol are introduced. The biobutadiene monomer is separated from the gas produced by the reaction. As a separation method, the generated gas is passed through a cooled condenser to separate heavy impurities such as unreacted bioethanol and water, and then the reaction gas is bubbled into an organic solvent to remove the biobutadiene monomer. It is dissolved in a solvent and recovered as a solution. Light impurities such as ethylene and carrier gas N ₂ are passed through without being dissolved in the organic solvent and discharged from the solvent tank.

[Method for producing isoprene-butadiene copolymer]
The production method of the isoprene-butadiene copolymer of the present invention is produced by solution polymerization. Such solution polymerization is usually performed in a hydrocarbon solvent of one or more aromatic, paraffinic or cycloparaffinic compounds. These solvents usually contain 4 to 10 carbon atoms per molecule and are liquid under polymerization conditions. Some representative examples of suitable organic solvents are pentane, isooctane, cyclohexane, n-hexane, benzene, toluene, xylene, ethylbenzene, etc., alone or as a mixture.

  In the solution polymerization, about 5 to about 35% by mass of monomer is usually included in a hydrocarbon solvent (polymerization medium). Such a polymerization medium is of course composed of an organic solvent, a 1,3-butadiene monomer and an isoprene monomer. Usually, it is desirable that the polymerization medium contains 10 to 30% by mass of monomer, more preferably 20 to 25% by mass.

  As described above, the content of the structural unit derived from the monomer constituting the isoprene-butadiene copolymer of the present invention is such that the content of the structural unit derived from the bioisoprene monomer is 10 to 60% by mass. The content of the structural unit derived from the butadiene monomer is preferably 40 to 90% by mass, and when it is an isoprene-butadiene-styrene copolymer, the content of the structural unit derived from the bioisoprene monomer The amount is 5 to 40% by mass, the content of the structural unit derived from the biobutadiene monomer is 30 to 90% by mass, and the content of the structural unit derived from styrene is 5 to 30% by mass. desirable. Therefore, it is preferable that the monomer ratio of the monomer-containing composition used for the polymerization contains 10 to 60% by mass of isoprene monomer and 40 to 90% by mass. In the case of an isoprene-butadiene-styrene copolymer, the monomer ratio of the monomer-containing composition is such that the content of the bioisoprene monomer is 5 to 40% by mass, and the biobutadiene monomer It is desirable that the content of is 30 to 90% by mass and the content of styrene is 5 to 30% by mass.

  The isoprene-butadiene copolymer is usually synthesized by a continuous method. In this continuous process, monomer and organolithium initiator are continuously fed to a reaction vessel or series of reaction vessels. The pressure in the reaction vessel is typically sufficient to maintain a substantially liquid phase under the polymerization reaction conditions. The reaction medium is generally maintained at about 70 to about 140 ° C. during the copolymerization. This is generally preferred when the copolymerization is carried out in a series of reaction vessels and when the reaction temperature is raised from reaction vessel to reaction vessel along with the polymerization process. For example, it is preferred to use a two reactor system that maintains the temperature of the first reactor at about 70-90 ° C and the temperature of the second reactor at about 90-about 100 ° C.

  Organic lithium compounds that can be used as an initiator in producing an isoprene-butadiene-styrene copolymer using a styrene monomer include organic monolithium compounds and organic monofunctional lithium compounds. . The organic polyfunctional lithium compound is generally an organic dilithium compound or an organic trilithium compound. Some representative examples of suitable polyfunctional organolithium compounds include 1,4-dilithiobutane, 1,10-dilithiodecane, 1,20-dilithioeicosane, 1,4-dilithiobenzene, 1,4-dilithio. Naphthalene, 9,10-dilithioanthracene, 1,2-dilithio-1,2-diphenylethane, 1,3,5-trilithiopentane, 1,5,15-trilithioeicosane, 1,3,5- Trilithiocyclohexane, 1,3,5,8-tetralithiodecane, 1,5,10,20-tetralithioeicosane, 1,2,4,6-tetralithiocyclohexane, 4,4'-dilithiobiphenyl, etc. There is.

  The organolithium compound used is usually an organic monolithium compound. A preferred organolithium compound can be represented by the formula: R—Li where R is a hydrocarbyl group having from 1 to about 20 carbon atoms. In general, such monofunctional organolithium compounds contain from 1 to about 10 carbon atoms. Some representative examples of organolithium compounds that can be used are methyllithium, ethyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, n-octyllithium, t-octyllithium, n-decyllithium, phenyllithium, 1- Naphthyl lithium, 4-butylphenyl lithium, p-tolyl lithium, 1-naphthyl lithium, 4-butylphenyl lithium, p-tolyl lithium, 4-phenylbutyl lithium, cyclohexyl lithium, 4-butylcyclohexyl lithium and 4-cyclohexylbutyl lithium It is.

  The amount of organolithium initiator used depends on the desired molecular weight of the isoprene-butadiene copolymer produced. The amount of organolithium initiator is selected such that an isoprene-butadiene copolymer having a Mooney viscosity of 55 to 140 is produced. Preferably, the amount of organolithium initiator is selected so that an isoprene-butadiene copolymer having a Mooney viscosity of 85-130 is produced. More preferably, the amount of organolithium initiator is selected such that an isoprene-butadiene copolymer having a Mooney viscosity of 115 to 125 is produced.

  In general, in all anionic polymerizations, the molecular weight (Mooney viscosity) of the polymer produced is inversely proportional to the amount of catalyst used. Generally from about 0.01 to about 1 phm (parts per hundred parts of monomer based on weight) of organolithium compounds are used. In most cases, it is preferred to use about 0.015 to about 0.1 phm of organolithium compound, and most preferably about 0.025 to 0.07 phm of organolithium compound.

  Under the conditions described above, the isoprene-butadiene copolymer is obtained by solution polymerization of the raw material, bioisoprene monomer and biobutadiene monomer, and styrene monomer used as necessary in a reaction vessel. Can be obtained. In addition, when using a styrene monomer, a fossil resource may be used as a starting material, and a biological resource including plant resources (so-called biomass) may be used as a raw material.

[Rubber composition]
The rubber composition of the present invention is not particularly limited as long as it contains the (co) polymer of the present invention, and can be appropriately selected according to the purpose, but rubber components other than the copolymer of the present invention, inorganic It preferably contains a filler, carbon black, a crosslinking agent, and the like.

<Rubber component>
The rubber component is not particularly limited and may be appropriately selected depending on the purpose. For example, the (co) polymer, natural rubber, epoxidized natural rubber, various butadiene rubbers, and various styrene-butadiene copolymers of the present invention are used. Polymer rubber, isoprene rubber, butyl rubber, bromide of copolymer of isobutylene and p-methylstyrene, halogenated butyl rubber, acrylonitrile butadiene rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer Examples thereof include coalesced rubber, styrene-isoprene copolymer rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, and urethane rubber. These may be used alone or in combination of two or more.
A reinforcing filler can be blended with the rubber composition as necessary. Examples of the reinforcing filler include carbon black and inorganic filler, and at least one selected from carbon black and inorganic filler is preferable.

<Inorganic filler>
The inorganic filler is not particularly limited and may be appropriately selected depending on the intended purpose.For example, silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloon, glass beads, calcium carbonate, Examples thereof include magnesium carbonate, magnesium hydroxide, calcium carbonate, magnesium oxide, titanium oxide, potassium titanate, and barium sulfate. These may be used alone or in combination of two or more. In addition, when using an inorganic filler, you may use a silane coupling agent suitably.
There is no restriction | limiting in particular as content of the said reinforcing filler, Although it can select suitably according to the objective, 5 mass parts-200 mass parts are preferable with respect to 100 mass parts of rubber components.
If the content of the reinforcing filler is less than 5 parts by mass, the effect of adding the reinforcing filler may not be seen so much, and if it exceeds 200 parts by mass, the rubber filler is mixed with the reinforcing filler. There is a tendency that it does not get caught, and the performance as a rubber composition may be reduced.

<Inorganic filler>
The crosslinking agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a sulfur-based crosslinking agent, an organic peroxide-based crosslinking agent, an inorganic crosslinking agent, a polyamine crosslinking agent, a resin crosslinking agent, and a sulfur compound. Of these, a sulfur-based crosslinking agent is more preferable as the rubber composition for tires.
There is no restriction | limiting in particular as content of the said crosslinking agent, Although it can select suitably according to the objective, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of rubber components.
When the content of the cross-linking agent is less than 0.1 parts by mass, the cross-linking hardly proceeds, and when the content exceeds 20 parts by mass, the cross-linking tends to progress during kneading with a part of the cross-linking agent. The physical properties of the sulfide may be impaired.

<Other ingredients>
In addition, it is also possible to use a vulcanization accelerator in combination, and examples of the vulcanization accelerator include guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, Dithiocarbamate and xanthate compounds can be used.
If necessary, reinforcing agents, softeners, fillers, vulcanization aids, colorants, flame retardants, lubricants, foaming agents, plasticizers, processing aids, antioxidants, anti-aging agents, scorch prevention agents, Known materials such as ultraviolet ray inhibitors, antistatic agents, anti-coloring agents, and other compounding agents can be used depending on the intended use.

<Crosslinked rubber composition>
The crosslinked rubber composition of the present invention is not particularly limited as long as it is obtained by crosslinking the rubber composition of the present invention, and can be appropriately selected according to the purpose.
The crosslinking conditions are not particularly limited and may be appropriately selected depending on the intended purpose. However, a temperature of 120 ° C. to 200 ° C. and a heating time of 1 minute to 900 minutes are preferable.

[tire]
The tire of the present invention is not particularly limited as long as the rubber composition of the present invention or the crosslinked rubber composition of the present invention is used, and can be appropriately selected according to the purpose.
Examples of the application site in the tire of the rubber composition of the present invention or the crosslinked rubber composition of the present invention include, but are not limited to, a tread, a base tread, a sidewall, a side reinforcing rubber, and a bead filler. .
As a method for manufacturing the tire, a conventional method can be used. For example, on a tire molding drum, members usually used for manufacturing a tire such as a carcass layer, a belt layer, and a tread layer made of unvulcanized rubber are sequentially laminated, and the drum is removed to obtain a green tire. Next, the desired tire can be manufactured by heat vulcanizing the green tire according to a conventional method.

  Further, the rubber composition of the present invention or the crosslinked rubber composition of the present invention can be used for anti-vibration rubber, seismic isolation rubber, belt (conveyor belt), rubber crawler, various hoses, Moran, etc. in addition to tire applications. The rubber composition of the invention or the crosslinked rubber composition of the invention can be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
[Production example of bioisoprene-butadiene copolymer]
<Manufacture of catalyst>
A silica-magnesia composite oxide synthesized by a sol-gel method was used as a catalyst. The synthesis method of this catalyst is as follows. First, Mg (OH) ₂ gel was synthesized by dropping 100 mL of a 14% aqueous ammonia solution into a solution of Mg (NO ₃ ) ₂ .6H ₂ O (64 g) dissolved in 100 mL of distilled water. On the other hand, Si (OH) ₄ gel was synthesized by dropping 12.5 mL of 1.38M nitric acid and 50 mL of 14% ammonia aqueous solution into a solution of Si (OC ₂ H ₅ ) ₄ (55 mL) dissolved in 150 mL of ethanol. The obtained Mg (OH) ₂ gel was subjected to suction filtration after washing with distilled water, and the Si (OH) ₄ gel was subjected to suction filtration after washing with ethanol. These two types of gels were mixed, and the mixed gel was air-dried, then dried at 80 ° C., 500 ° C., and calcined in an N ₂ atmosphere to produce a silica-magnesia composite oxide catalyst.

<Production of biobutadiene monomer>
Bioethanol obtained by fermenting sugarcane, tapioca and corn starches with yeast was used as a starting material.
A biobutadiene monomer was produced by contacting the catalyst produced by the above method with the bioethanol.
As the reaction apparatus, a generally known fixed bed gas flow type catalytic reaction apparatus (for example, JP-A-2009-51760) was used. The manufactured reaction tube made of silica-magnesia composite oxide catalyst quartz was filled, and as a pretreatment, heat treatment was performed at 500 ° C. for 2 hours in a carrier gas atmosphere (N ₂ ; gas flow rate 66 mL / min).
After completion of the pretreatment, the temperature of the catalyst tube was lowered to the reaction temperature, and bioethanol gas diluted with N ₂ was introduced. The reaction temperature at this time was 350 degreeC or 450 degreeC.
The mixture containing the biobutadiene monomer was recovered by performing the following separation operation on the gas generated by the reaction. First, the product gas was bubbled into hexane, so that the target biobutadiene monomer was dissolved in the solvent. The recovered butadiene solution was purified by drying to further remove impurities such as ethanol, acetaldehyde, diethyl ether, ethoxyethylene, and ethyl acetate.

[Production of Polymer A]
Two reactors maintained at 95 ° C. (10 liters each) were used in succession as reactors. A bioisoprene monomer obtained by decomposing sugarcane cellulose as a starting material and a biobutadiene monomer (1, 3) using isoprene-producing bacteria in which isoprene / synthase / polypeptide is incorporated into Escherichia coli in hexane -Butadiene) was continuously charged into the first polymerization reactor at a rate of 100 g / min. The total monomer concentration of the monomer mixed solution containing bioisoprene to biobutadiene in a ratio of 30:70 was 11%. The polymerization was initiated by adding a 0.107M solution of n-butyllithium to the first reactor at a rate of 0.32 g / min. The residence time for both reactors was set at 1.16 hours. When the average monomer conversion was measured, it was 62% in the first reactor and 93% in the second reactor.
The polymerization medium was continuously extruded from the second reactor into a holding tank containing methanol (as a polymerization terminator) and an antioxidant. Next, the obtained polymer cement was steam stripped, and the recovered bioisoprene-butadiene copolymer was dried at 60 ° C. in a vacuum. Since the bioisoprene monomer and biobutadiene monomer were continuously pumped into the reactor, the isoprene distribution in the bioisoprene-butadiene copolymer was random. When the obtained polymer A was measured, the glass transition temperature was -84 degreeC and the Mooney ML-4 viscosity was 85. It was also measured to have a microstructure comprising 6% 1,2-polybutadiene units, 60% 1,4-polybutadiene units, 32% 1,4-polyisoprene units and 2% 3,4-polyisoprene units. Met.

[Production of polymer B]
A polymer B was produced in the same manner as in the production of the polymer A, except that the bioisoprene monomer and the biobutadiene monomer were replaced with the isoprene monomer and butadiene monomer obtained from the petroleum raw material, respectively. When the obtained polymer B was measured, the glass transition temperature was -84 degreeC and the Mooney ML-4 viscosity was 85. It was also measured to have a microstructure comprising 6% 1,2-polybutadiene units, 60% 1,4-polybutadiene units, 32% 1,4-polyisoprene units and 2% 3,4-polyisoprene units. Met.

[Evaluation method]
<Physical properties of isoprene-butadiene copolymer>
<< Microstructure [polybutadiene: cis-1,4 bond content (%), 1,2-vinyl bond content (%), polyisoprene: cis-1,4 bond content (%), 3,4-vinyl bond content ( %)] >>
A Fourier transform infrared branch photometer (FT / IR-4100, manufactured by JASCO Corporation) was used, and measurement was performed by an infrared method (Morero method).
≪Ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) of isoprene-butadiene copolymer (Mw / Mn) ≫
Using gel permeation chromatography (trade name “HLC-8120GPC”, manufactured by Tosoh Corporation), a differential refractometer was used as a detector, and measurement was performed under the following conditions to calculate a standard polystyrene equivalent value.
Column: Trade name “GMHHXL” (manufactured by Tosoh Corporation) 2 Column temperature: 40 ° C.
Mobile phase: Tetrahydrofuran Flow rate: 1.0 ml / min
Sample concentration: 10 mg / 20 ml

<Measurement of Δ14C>
Bioisoprene monomer obtained by decomposing sugarcane cellulose as a starting material using isoprene-producing bacteria in which isoprene / synthase / polypeptide is incorporated into Escherichia coli, and starch from sugarcane, tapioca and corn as starting materials The value of δ13C of the carbon atom derived from the biobutadiene monomer in the isoprene-butadiene copolymer produced using bioethanol obtained by fermenting the quality with yeast was measured with a stable isotope ratio measuring device. Δ14C was calculated by the conversion method described above.

<Measurement of ¹⁴ C decay per gram per minute>
Accelerator mass spectrometry (Accelerator) was used to determine the amount of carbon atom ¹⁴ C decay per gram per minute derived from biobutadiene monomer in an isoprene-butadiene copolymer prepared from bioisoprene monomer and biobutadiene monomer. It was measured by Mass Spectrometry (AMS) and a liquid scintillation counting method (LSC).

<Measurement of δ13C>
The value of δ13C of the carbon atom derived from the bioisoprene monomer in the isoprene-butadiene copolymer produced from the bioisoprene monomer and the biobutadiene monomer was measured with a stable isotope ratio measuring device.

<Evaluation of crack growth resistance and low heat build-up of rubber composition>
The crack growth resistance and low exothermic properties of a rubber composition containing an isoprene-butadiene copolymer produced from a bioisoprene monomer and a biobutadiene monomer were measured by the following methods.
The rubber composition of the present invention includes a rubber component containing the above isoprene-butadiene copolymer, carbon black, vulcanizing agent, vulcanization accelerator, anti-aging agent, scorch preventing agent, softening agent, zinc oxide. The compounding agents normally used in the rubber industry such as stearic acid and silane coupling agents can be appropriately selected and blended. In addition, the said rubber composition can be manufactured by mix | blending the various compounding agent suitably selected as needed with the rubber component, kneading | mixing, heating, extrusion, etc.

≪Crack growth resistance≫
A 0.5 mm crack was made in the center part of the JIS No. 3 test piece, fatigue was repeatedly given at a strain of 50 to 100% at room temperature, and the number of times until the sample was cut was measured. The value at each strain was determined and the average value was used. In Table 2, it represented with the parameter | index which sets the comparative example 1 which mix | blended the polymer A to 100. The larger the index value, the better the crack growth resistance.

≪Low heat generation (3% tan δ) ≫
A dynamic spectrometer (manufactured by Rheometrics, USA) was used, and measurement was performed under the conditions of tensile dynamic strain of 3%, frequency of 15 Hz, and 50 ° C. In Table 2, it represented with the parameter | index which sets the comparative example 1 which mix | blended the polymer A to 100. It shows that it is excellent in low exothermic property (low loss property), so that an index value is small.

[Example 1, Comparative Example 1]
Using each of the polymers A and B, a rubber composition was prepared according to the formulation shown in Table 1, and vulcanized at 145 ° C. for 33 minutes to obtain a vulcanized rubber.
The physical properties of polymers A and B and the value of δ13C were measured by the above methods. Further, the crack growth resistance and low exothermic property (3% tan δ) of the obtained vulcanized rubber were measured according to the evaluation method described above. The results are shown in Table 2.

※ 1: nitrogen adsorption specific surface area of the carbon black used; 42m ² / g
* 2: N- (1,3-dimethylbutyl) -N′-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., NOCRACK 6C
* 3: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Co., Ltd., NOCRACK 224
* 4: N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd., Noxeller CZ-G
* 5: Dibenzothiazyl disulfide, manufactured by Ouchi Shinsei Chemical Co., Ltd., Noxeller DM-P

Mn of the obtained polymer A was 200,000 and Mw / Mn = 1.8.
Moreover, Mn of the obtained polymer B was 200,000 and Mw / Mn = 1.8.
The obtained polymer A had a δ13C value of −14.69 and a Δ14C value of −1000. Further, the value of δ13C of the polymer B was −23.00, and the value of Δ14C was −100.
From the above results, a polymer A (bio-derived isoprene-butadiene copolymer) having a value of δ13C of carbon atoms derived from the isoprene monomer in the bioisoprene-butadiene copolymer of −14.69 was used. Comparative example using polymer B (ordinary isoprene-butadiene copolymer) having a value of δ13C of −23.00 as an index of crack growth resistance and an index of 3% tan δ of the vulcanized rubber of Example 1 The value was similar to that of No. 1 vulcanized rubber, and was found to be comparable to conventional products in crack growth resistance and low heat build-up.

Claims (11)

  An isoprene-butadiene copolymer obtained by copolymerizing a biobutadiene monomer and a bioisoprene monomer synthesized from biological resources including plant resources, the carbon atom derived from the bioisoprene monomer Isoprene having a δ13C value of −30 ‰ to −28.5 ‰, or −22 ‰ or more, and a Δ14C value of carbon atoms derived from the biobutadiene monomer of −75 to −225 ‰ Butadiene copolymer. An isoprene-butadiene copolymer obtained by copolymerizing a biobutadiene monomer and a bioisoprene monomer synthesized from a biological resource including a plant resource, the carbon atom derived from the biobutadiene monomer ¹⁴ C isoprene-butadiene copolymer having a decay amount per gram per minute of 0.1 dpm / gC or more.   The isoprene-butadiene copolymer according to claim 1 or 2, wherein the isoprene-butadiene copolymer has a molecular weight of 1,000 to 5,000,000.   The isoprene-butadiene copolymer is an isoprene-butadiene-styrene copolymer obtained by copolymerizing a biobutadiene monomer synthesized from biological resources including plant resources, a bioisoprene monomer, and styrene. Item 4. The isoprene-butadiene copolymer according to any one of Items 1 to 3.   The content of the structural unit derived from the bioisoprene monomer is 10 to 60% by mass, and the content of the structural unit derived from the biobutadiene monomer is 40 to 90% by mass. The isoprene-butadiene copolymer described.   The content of the structural unit derived from the bioisoprene monomer is 5 to 40% by mass, the content of the structural unit derived from the biobutadiene monomer is 30 to 90% by mass, and the content of the structural unit derived from styrene The isoprene-butadiene copolymer according to claim 4, wherein the amount is 5 to 30% by mass.   It is a manufacturing method of the isoprene-butadiene copolymer in any one of Claims 1-6, Comprising: The mixture containing the bioisoprene monomer and the biobutadiene monomer from the biological origin resources containing a plant resource is produced | generated. And a method of producing an isoprene-butadiene copolymer that is copolymerized using the mixture.   Bio-ethanol is synthesized from bio-derived resources including plant resources, and the bio-butadiene monomer is brought into contact with the composite metal oxide containing at least magnesium and silicon as metal elements under heating. The manufacturing method of the isoprene-butadiene copolymer of Claim 7 which produces | generates the mixture containing and manufactures an isoprene-butadiene copolymer using this biobutadiene monomer.   Bioisoprene monomer synthesized from biological resources including plant resources is cultured in cells containing heterologous nucleic acid encoding isoprene / synthase / polypeptide under culture conditions suitable for isoprene production, and the culture The method for producing an isoprene-butadiene copolymer according to claim 7 or 8, wherein the isoprene-butadiene copolymer is produced using a bioisoprene monomer obtained by recovering from the product.   A rubber composition comprising the isoprene-butadiene copolymer according to any one of claims 1 to 6.   A tire comprising the rubber composition according to claim 10.