WO2013081138A1

WO2013081138A1 - Modified cellulose fibers and rubber composition containing modified cellulose fibers

Info

Publication number: WO2013081138A1
Application number: PCT/JP2012/081179
Authority: WO
Inventors: 矢野　浩之; 文明中坪; 隼人加藤
Original assignee: 国立大学法人京都大学
Priority date: 2011-11-30
Filing date: 2012-11-30
Publication date: 2013-06-06
Also published as: JP6014860B2; JPWO2013081138A1

Abstract

Provided are: a rubber composition, wherein modified cellulose fibers are well dispersed in a highly hydrophobic rubber component, and wherein not only the rubber composition is crosslinked but also a crosslinked structure is formed between the rubber component and the modified cellulose fibers by means of a crosslinking agent; and novel modified cellulose fibers which constitute the cellulose fibers to be used in the rubber composition and wherein hydrogen atoms in some hydroxy groups in the cellulose are modified by substituents each containing a hydrocarbon group that has an unsaturated bond. Modified cellulose fibers wherein hydrogen atoms in some hydroxy groups in the cellulose that constitutes the cellulose fibers are substituted by substituents that are represented by formula (1): -A-R¹. (In formula (1), R¹ represents a hydrocarbon group having at least one unsaturated bond and 3-30 carbon atoms; and A represents a carbonyl group (-CO-) or a single bond (-).)

Description

Modified cellulose fiber and rubber composition containing modified cellulose fiber

The present invention relates to a modified cellulose fiber substituted with a substituent containing a hydrocarbon group having at least one unsaturated bond, and a rubber composition containing the modified cellulose fiber.

Cellulose fiber is the basic skeletal material of all plants and has an accumulation of over 1 trillion tons on the earth. Cellulose fiber is a fiber having a strength five times that of steel and a low linear thermal expansion coefficient of 1/50 that of glass, although it is 1/5 lighter than steel. It is expected to be used as a filler in a matrix such as rubber to impart mechanical strength.

However, cellulose fibers rich in hydroxyl groups are hydrophilic, highly polar, and poorly compatible with general-purpose resins such as rubber and polypropylene that are hydrophobic. Therefore, when cellulose fibers are blended in these material matrices, agglomeration occurs, and the material is rather inferior in mechanical strength.

Some chemical treatment is indispensable for exhibiting a high reinforcing effect as a filler. For example, Patent Document 1 describes a modified cellulose nanofiber obtained by modifying a cellulose nanofiber with a substituent such as an alkanoyl group.

However, when the modified cellulose fiber as described above is blended with a matrix material such as highly hydrophobic resin or rubber, the dispersibility of the modified cellulose fiber in the matrix is improved, but the matrix and the modified cellulose fiber are not dispersed. The present situation is that no chemical bond between them is brought about, and sufficient elastic properties and low linear thermal expansibility cannot be exhibited.

JP 2007-51266 A

In the present invention, the modified cellulose fiber is well dispersed in the rubber component having high hydrophobicity, and the crosslinked structure is not only formed by the crosslinking agent but also between the rubber component and the modified cellulose fiber. It aims at providing the rubber composition which can be formed.

The present invention also provides a novel modified cellulose obtained by modifying hydrogen atoms of some hydroxyl groups in cellulose constituting the cellulose fiber used in the rubber composition with a substituent containing a hydrocarbon group having an unsaturated bond. It is also an object to provide a fiber.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have modified the hydrogen atoms of some hydroxyl groups in cellulose constituting the cellulose fiber to specific substituents having an unsaturated bond. It has been found that modified cellulose fibers can be well dispersed in a highly hydrophobic rubber component, and that a crosslinked structure with sulfur can be formed between the rubber component and the cellulose fiber. It was.

The present invention is an invention that has been completed based on such findings and further earnest studies. That is, this invention provides the modified cellulose fiber shown to the following term, its manufacturing method, and the rubber composition containing the said modified cellulose fiber.

Item 1. Hydrogen atoms of some hydroxyl groups in cellulose constituting the cellulose fiber are represented by the formula (1):
-AR ¹ (1)
(In formula (1), R ¹ is a hydrocarbon having 3 to 30 carbon atoms having at least one unsaturated bond, and A is a carbonyl group (—CO—) or a single bond (—)).
The modified cellulose fiber substituted by the substituent represented by these.

Item 2. Item 2. The modified cellulose fiber according to Item 1, wherein the cellulose fiber is a fibrillated cellulose fiber.

Item 3. Item 3. The modified cellulose fiber according to

Item

1 or 2, wherein the degree of substitution (DS) is 0.05 to 2.0.

Item 4. Cellulose fiber is represented by the formula (1 ′):
R ¹ -AB (1 ')
(Wherein A is a carbonyl group (—CO—) or a single bond (−), and B is a leaving group)
The manufacturing method of the modified cellulose fiber including the process modified | denatured with the modifier | denaturant represented by these.

Item 5. Item 5. The method for producing a modified cellulose fiber according to Item 4, wherein the cellulose fiber is a fibrillated cellulose fiber.

Item 6. Item 4. A rubber composition comprising the modified cellulose fiber according to any one of Items 1 to 3 and a rubber component.

Item 7. Item 7. The rubber composition according to Item 6, further comprising sulfur.

Item 8. Item 8. A vulcanized product obtained by vulcanizing the rubber composition according to Item 7.

In the modified cellulose fiber of the present invention, the hydrogen atoms of some hydroxyl groups in the cellulose constituting the cellulose fiber are modified by a substituent having a hydrocarbon, so that the hydrophilicity of the cellulose fiber can be reduced, It can be well dispersed in a matrix material such as rubber having high hydrophobicity.

In addition, the hydrocarbon forming the substituent, which is a modified part, has at least one unsaturated bond, and therefore, a modified cellulose fiber is blended in the rubber component, and a vulcanizing agent such as sulfur is blended. As a result, not only the cross-linked structure is formed by sulfur in the rubber component, but also a cross-linked structure by sulfur is formed and chemically bonded between the rubber component and the modified cellulose fiber. Therefore, the vulcanizate formed from the rubber composition of the present invention has an effect that the elastic modulus is high and the linear thermal expansion coefficient is very low.

2 is an SEM image of fibrillated cellulose (FC) produced in Reference Example 1 at a magnification of 20,000 times. FIG. 3 is an SEM image at a magnification of 20,000 times of a modified FC (crtFC) modified with trans-crotonic acid chloride produced in Example 1-1. FIG. 2 is an SEM image at a magnification of 20,000 times of a modified FC (oleFC) modified with cis-oleoyl chloride produced in Example 1-2. FIG. 3 is an SEM image of a modified FC (orFC) modified with trans, trans-sorbic acid chloride produced in Example 1-3 at a magnification of 20,000 times. FIG. FIG. 5 is an SEM image at a magnification of 20,000 times of a modified FC (acFC) modified with acetyl chloride produced in Comparative Example 1-1. FIG. 3 is an SEM image of a modified FC (myrFC) modified with myristoyl chloride produced in Comparative Example 1-2 at a magnification of 20,000 times. FIG. 3 is an SEM image at a magnification of 20,000 times of a modified FC (stFC) modified with stearoyl chloride produced in Comparative Example 1-3. It is the spectrum of FC manufactured in Reference Example 1 measured by FT-IR analysis. 2 is a spectrum of crtFC produced in Example 1-1, measured by FT-IR analysis. It is the spectrum of oleFC manufactured in Example 1-2 measured by FT-IR analysis. It is the spectrum of sorFC manufactured in Example 1-3 measured by FT-IR analysis. 2 is a spectrum of acFC produced in Comparative Example 1-1, measured by FT-IR analysis. 2 is a spectrum of myrFC produced in Comparative Example 1-2, measured by FT-IR analysis. It is the spectrum of stFC manufactured in Comparative Example 1-3 measured by FT-IR analysis. Each vulcanized rubber sheet produced in Reference Example 2-1, Reference Example 2-2, Reference Example 2-3, Example 2-1, Example 2-2, Comparative Example 2-1, and Comparative Example 2-2 Is a graph in which a stress-strain curve is plotted. 6 is a graph plotting stress-strain curves for each vulcanized rubber sheet obtained in Example 2-2 and Comparative Example 2-3. Thermal expansion at various temperatures for each vulcanized rubber sheet produced in Reference Example 2-1, Reference Example 2-3, Example 2-1, Example 2-2, and Comparative Examples 2-1 to 2-3 ( It is the graph which plotted Thermal (expansion). The storage elastic modulus at each temperature for each vulcanized rubber sheet (containing 5% by weight of (modified) FC) produced in Reference Example 2-2, Reference Example 2-3, Example 2-2, and Comparative Example 2-3. This is a plotted graph. The tan δ at each temperature was plotted for each vulcanized rubber sheet (containing 5% by weight of (modified) FC) produced in Reference Example 2-2, Reference Example 2-3, Example 2-2, and Comparative Example 2-3. It is a graph.

Hereinafter, the modified cellulose fiber of the present invention, a rubber composition containing the modified cellulose fiber, a method for producing the same, and a molding material using the rubber composition will be described in detail.

1. Modified cellulose fiber In the modified cellulose fiber of the present invention, hydrogen atoms of some hydroxyl groups in cellulose constituting the cellulose fiber are represented by the formula (1):
-AR ¹ (1)
It has the structure substituted by the substituent represented by these.

R ¹ in the formula (1) is a hydrocarbon group having 3 to 30 carbon atoms, preferably about 3 to 20 carbon atoms, having at least one unsaturated bond. By setting the number of carbon atoms of the hydrocarbon group to 3 or more, it reacts with a crosslinking agent such as sulfur by dehydrogenation of α-methyl or α-methylene located next to the unsaturated bond from C—H. It becomes possible. When the number of unsaturated bonds is 2 or more, the lower limit of the carbon number of the hydrocarbon group is 2Y + 1 (Y represents the number of unsaturated bonds).

Moreover, hydrophobicity can be imparted to the cellulose fiber by setting the number of carbon atoms of the hydrocarbon group to 30 or less. Examples of the unsaturated bond in R ¹ include a double bond and a triple bond. Among these, a double bond is preferable. The number of unsaturated bonds in R ¹ may be 1 or may be 2 or more. The upper limit of the number of unsaturated bonds is not particularly limited, but for example, about 6 is preferable.

When the unsaturated bond in R ¹ is a double bond, it has a cis isomer or a trans isomer, but is not particularly limited, and any structural isomer can be applied.

In the formula (1), A represents a carbonyl group (—CO—) or a single bond (—).

Specific examples of the structure (—CO—R ¹ ) when A in the formula (1) is a carbonyl group (—CO—) include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vacsen Monounsaturated aliphatic carboxylic acids such as acid, gadoleic acid, eicosenoic acid, erucic acid and nervonic acid; diunsaturated aliphatic carboxylic acids such as sorbic acid, linoleic acid, eicosadienoic acid and docosadienoic acid; linolenic acid, pinolenic acid, Triunsaturated aliphatic carboxylic acids such as eleostearic acid, dihomo-γ-linolenic acid, eicosatrienoic acid; tetraunsaturated aliphatic carboxylic acids such as stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid; Penta unsaturation such as boseopentaenoic acid, eicosapentaenoic acid, ozbond acid, sardine acid, tetracosapentaenoic acid Aliphatic carboxylic acid; a residue obtained by removing —OH from a carboxylic acid group in an unsaturated aliphatic carboxylic acid such as hexaunsaturated aliphatic carboxylic acid such as docosahexaenoic acid and nisic acid.

Specific examples of the structure (—R ¹ ) when A in the formula (1) is a single bond (—) include allyl alcohol, octadecadienol, docosenol, dodecedienol, oleyl alcohol, tridecenol, linolyl. Examples thereof include residues obtained by removing —OH groups from unsaturated alcohols such as alcohols.

The substituent represented by the above formula (1) modified on the cellulose fiber may have one or more substituents.

The degree of substitution (DS) of the modified cellulose fiber is 0 because the highly hydrophilic cellulose fiber is uniformly dispersed in a highly hydrophobic rubber component matrix or the water resistance of the cellulose fiber is improved. About 0.05 to 2.0, preferably about 0.1 to 2.0, and more preferably about 0.1 to 0.8.

DS should be analyzed by various analytical methods such as weight gain, elemental analysis, neutralization titration, FT-IR, ¹ H and ¹³ C-NMR after removing by-products from the modified cellulose fiber. Can do.

In addition to the substitution by the substituent represented by the above formula (1), in order to further improve the hydrophobicity of the modified cellulose fiber, the hydrogen atoms of some hydroxyl groups of the cellulose in the modified cellulose fiber are optionally included. For example, formula (2):
-A-R ^a (2)
(In the formula (2), R ^a is a linear or branched alkyl group having 1 to 30 carbon atoms, and A is a carbonyl group (—CO—) or a single bond (—)).
It may be substituted by a substituent represented by

Cellulose fibers used as raw materials for modified cellulose fibers include pulps obtained from natural plant materials such as wood, bamboo, hemp, jute, kenaf, cotton, beet, agricultural waste, and cloth; regenerated cellulose fibers such as rayon and cellophane Can be mentioned. Among these, pulp and fibrillated cellulose obtained by fibrillating pulp are preferable raw materials.

The pulp includes chemical pulp (kraft pulp (KP), sulfite pulp (SP)), semi-chemical pulp (SCP) obtained by pulping plant raw materials chemically or mechanically, or a combination of both. ), Chemi-Grand Pulp (CGP), Chemi-Mechanical Pulp (CMP), Groundwood Pulp (GP), Refiner Mechanical Pulp (RMP), Thermo-Mechanical Pulp (TMP), Chemi-thermo-Mechanical Pulp (CTMP), and these pulps Preferred examples include deinked waste paper pulp, corrugated waste paper pulp and magazine waste paper pulp as components. These raw materials can be delignified or bleached as necessary to adjust the amount of lignin in the pulp.

Among these pulps, various kraft pulps derived from conifers with strong fiber strength (coniferous unbleached kraft pulps (hereinafter sometimes referred to as NUKP), softwood oxygen-bleached unbleached kraft pulps (hereinafter sometimes referred to as NOKPs), Softwood bleached kraft pulp (hereinafter sometimes referred to as NBKP)) is particularly preferred.

Pulp is mainly composed of cellulose, hemicellulose, and lignin. The lignin content in the pulp is not particularly limited, but is usually about 0 to 40% by weight, preferably about 0 to 10% by weight. The lignin content can be measured by the Klason method.

The modified cellulose fiber of the present invention can be obtained by substituting a hydrogen atom of a hydroxyl group of a part of cellulose constituting the cellulose fiber with a substituent represented by the above formula (1). By increasing the specific surface area of the cellulose fiber, the contact area with the rubber can be increased, and the modified cellulose fiber into which a substituent having an unsaturated bond is introduced and the rubber component has a more crosslinked structure with sulfur. It can be formed firmly.

Examples of the cellulose fiber having a large specific surface area include fibrillated cellulose obtained by fibrillating the pulp.

The specific surface area of the modified cellulose fiber is not particularly limited, and is preferably about 10 to 400 m ² / g, for example, from the viewpoint of increasing the contact area with the rubber component, cost, etc., and 20 to 300 m ^2. / G is more preferable, and about 30 to 300 m ² / g is still more preferable. The average diameter of the modified cellulose fiber is usually about 4 nm to 500 μm, preferably about 10 nm to 500 μm, particularly preferably about 20 nm to 200 μm.

In the cell walls of plants, cellulose microfibrils (single cellulose nanofibers) with a width of about 4 nm are present as a minimum unit. And this cellulose nanofiber gathers and forms the plant cell which is the plant cell and also the aggregate. In the present invention, cellulose fiber obtained by using plant fiber as a raw material is substituted with a substituent represented by the above formula (1).

Further, the cellulose fiber may be fibrillated cellulose obtained by unwinding cellulose fiber obtained from a material containing plant fiber (for example, wood pulp, cotton, etc.) until it becomes a bundle of fibrils or cellulose microfibrils.

The modified cellulose fiber of the present invention has a structure in which a part of hydroxyl groups in cellulose constituting the cellulose fiber is modified with a substituent having a hydrocarbon group having an unsaturated bond as described above. Hydrophobicity can be imparted to the fiber. Therefore, the modified cellulose fiber can be well dispersed in a matrix such as a rubber component having high hydrophobicity.

In addition, since the modified substituent in the modified cellulose fiber has a hydrocarbon group having an unsaturated bond, the CH of α-methyl or α-methylene located next to the unsaturated bond is easily dehydrogenated. It has a structure. Therefore, if the modified cellulose fiber of the present invention and a crosslinking agent such as sulfur are blended in a matrix material such as a rubber component capable of forming a crosslink and crosslinked, the matrix and the cellulose fiber are not only crosslinked between the matrix materials. It is possible to form a cross-linked structure between the two.

Therefore, the modified cellulose fiber of the present invention can be suitably used as a reinforcing agent for a matrix material such as a rubber component used by being blended with a crosslinking agent such as sulfur.

2. Method for Producing Modified Cellulose Fiber The method for producing a modified cellulose fiber of the present invention includes a step of modifying cellulose fiber with a modifying agent.

As the cellulose fiber used as a raw material, those mentioned in the above-mentioned “1. Modified cellulose fiber” can be used. In addition, the cellulose fiber can increase the contact area with the rubber component by increasing the specific surface area, and a sulfur-crosslinked structure between the modified cellulose fiber introduced with a substituent having an unsaturated bond and the rubber component. From the viewpoint that it can be formed more firmly, fibrillated cellulose obtained by fibrillating pulp or the like can be used.

As a method of fibrillating cellulose fibers to obtain fibrillated cellulose, a method of defibrating pulp can be mentioned. As the defibrating method, a known method can be adopted, for example, an aqueous suspension or slurry of the pulp-containing material, a refiner, a high-pressure homogenizer, a grinder, a uniaxial or multiaxial kneader (preferably a biaxial kneader), a bead mill. It is possible to use a method of mechanically grinding or defibrating by beating. You may process combining the said defibrating method as needed.

As these defibrating methods, for example, the defibrating methods described in Japanese Patent Application Nos. 2011-079440, JP2011-213754, and JP2011-195738 can be used.

The cellulose fiber is modified with a modifying agent.

As the denaturing agent, the formula (1 ′):
R ¹ -AB (1 ')
(In the formula, A is a carbonyl group (—CO—) or a single bond (—), and B is a leaving group)
Represented by

As the leaving group for B in the formula (1 ′), a halogen atom, a hydroxyl group, or —OCOR ²
(Wherein R ² is R ¹ or a lower alkyl group).

The “lower” of the lower alkyl group in R ² means “1 to 5 carbon atoms, preferably 1 to 3 carbon atoms”.

When A in formula (1 ′) is a single bond (−) as a modifying agent, modified cellulose in which A in formula (1) is substituted with a substituent that is a single bond (−) When a fiber is obtained and a modifying agent in which A in the formula (1 ′) is a carbonyl group (—CO—) is used, A in the formula (1) is a carbonyl group (—CO—). A modified cellulose fiber substituted with a substituent group is obtained.

Examples of the modifying agent include those in which A in the formula (1 ′) is a single bond (−) and B is a hydroxyl group (R ¹ —OH). Specific examples include allyl alcohol, octadecadienol, docosenol. And unsaturated alcohols such as dodecedienol, oleyl alcohol, tridecenol, and linoleyl alcohol.

As a modifying agent, a specific example in which A in the formula (1 ′) is a single bond (−) and B is a halogen atom, the —OH group of the unsaturated alcohol is substituted with a halogen atom. And halogenated hydrocarbons having at least one unsaturated bond.

Specific examples of the modifying agent (R ¹ —CO—B) in which A in the formula (1 ′) is a carbonyl group (—CO—) include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid Monounsaturated aliphatic carboxylic acids such as elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid and nervonic acid; diunsaturated aliphatic carboxylic acids such as sorbic acid, linoleic acid, eicosadienoic acid and docosadienoic acid; Triunsaturated aliphatic carboxylic acids such as acid, pinolenic acid, eleostearic acid, dihomo-γ-linolenic acid and eicosatrienoic acid; tetraunsaturated such as stearidonic acid, arachidonic acid, eicosatetraenoic acid and adrenic acid Aliphatic carboxylic acids; pentasenopentaenoic acid, eicosapentaenoic acid, ozbond acid, sardine acid, tetracosapentaenoic acid, etc. Japanese aliphatic carboxylic acids; unsaturated aliphatic carboxylic acids such as hexaunsaturated aliphatic carboxylic acids such as docosahexaenoic acid and nisic acid, and acid halides and acid anhydrides of these unsaturated aliphatic carboxylic acids. .

By reacting the modifying agent of the formula (1 ′) with cellulose fiber, the substituent represented by the formula (1) is substituted with a hydrogen atom of a hydroxyl group of a part of cellulose constituting the cellulose fiber.

The blending amount of the modifying agent when the cellulose fiber is modified with the modifying agent represented by the formula (1 ′) is preferably about 0.1 to 20 mol with respect to 1 mol of glucose unit of the cellulose fiber. About 0.4 to 10 mol is more preferable.

It is also possible to stop the reaction after adding the above modifier to cellulose fiber in excess and reacting to a predetermined DS. It is also possible to react to a predetermined DS by adjusting the catalyst amount and the like.

In order to further improve the hydrophobicity of the modified cellulose fiber modified by the modifying agent represented by the above formula (1 ′), the modified cellulose fiber may be modified, for example, by formula (2 ′):
B-A-R ^a (2 ')
(In the formula (2 ′), R ^a has the same definition as in the formula (2), B represents a leaving group, and A represents a carbonyl group (—CO—) or a single bond (—). It may be modified by a modifying agent represented by

By reacting the modifying agent of the above formula (2 ′) with the modified cellulose fiber, the substituent represented by the above formula (2) is further substituted with the hydrogen atom of the remaining hydroxyl group of cellulose constituting the modified cellulose fiber. be able to.

The reaction of modifying the cellulose fiber with the above-described modifying agent can be progressed to some extent by heating if sufficient dehydration is performed without using a catalyst, but the use of a catalyst is milder. It is more preferable because the cellulose fiber can be modified under conditions and with high efficiency.

Examples of the catalyst used for modification of cellulose fiber include acids such as hydrochloric acid, sulfuric acid and acetic acid, and amine catalysts. The acid catalyst is usually an aqueous solution, and in addition to esterification by addition of the acid catalyst, acid hydrolysis of the cellulose fiber may occur, so an alkali catalyst or an amine catalyst is more preferable.

Specific examples of the amine catalyst include pyridine compounds such as pyridine and dimethylaminopyridine (DMAP), and non-cyclic or cyclic tertiary amine compounds such as triethylamine, trimethylamine and diazabicyclooctane. Of these, pyridine, dimethylaminopyridine (DMAP), and diazabicyclooctane are preferable from the viewpoint of excellent catalytic activity. If necessary, powders of alkali compounds such as potassium carbonate and sodium carbonate may be used as a catalyst, or may be used in combination with an amine compound.

The compounding amount of the amine catalyst is equimolar or more than that of the modifying agent. For example, in the case of a liquid amine compound such as pyridine, a larger amount may be used as a catalyst and solvent. The amount used is, for example, about 0.1 to 10 moles per mole of glucose units in the cellulose fiber. The catalyst can be added to the cellulose fiber in excess, and the reaction can be stopped after reacting to the prescribed DS, or the required minimum catalyst is added, and the reaction time, temperature, etc. are adjusted. It is also possible to react up to the DS. It is generally preferable to remove the catalyst after the reaction by washing, distillation or the like.

The DS of the modified cellulose fiber modified with the modifying agent is preferably in the above-mentioned range.

The reaction temperature when the cellulose fiber is modified with a modifying agent is preferably about 20 to 160 ° C., more preferably about 40 to 120 ° C., and further preferably about 60 to 100 ° C. A higher temperature is preferable because the reaction efficiency of the cellulose fiber is higher. However, if the temperature is too high, the cellulose fiber is partially deteriorated. Therefore, the above temperature range is preferable.

Further, the modification of cellulose fiber can be performed in water, but the reaction efficiency is very low, so that it is preferably performed in a non-aqueous solvent. The non-aqueous solvent is preferably an organic solvent that does not react with the modifying agent. Specific examples include non-aqueous solvents such as halogenated solvents such as methylene chloride, chloroform, and carbon tetrachloride; ketone solvents such as acetone and methyl ethyl ketone (MEK); tetrahydrofuran (THF), ethylene glycol, propylene glycol, polyethylene glycol, and the like. Ether solvents such as dimethyl and diethyl compounds of ethers; amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, nonpolar solvents such as hexane, heptane, benzene and toluene, or a mixed solvent thereof .

The modified cellulose fiber may be further defibrated by the above production method in order to improve the specific surface area. As a method of defibrating, the methods mentioned above are used.

3. Rubber composition The rubber composition of the present invention comprises a modified cellulose fiber and a rubber component.

As the modified cellulose fiber, those mentioned in “1. Modified cellulose fiber” can be used.

Examples of the rubber component include diene rubber components. Specifically, natural rubber (NR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber (IR), butyl rubber (IIR). ), Acrylonitrile-butadiene rubber (NBR), acrylonitrile-styrene-butadiene copolymer rubber, chloroprene rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, hydrogen Natural rubber, deproteinized natural rubber and the like.

These rubber components may be used alone or in a blend of two or more. What is necessary is just to mix | blend suitably also in the blend ratio in the case of blending according to various uses.

The content of the modified cellulose fiber in the rubber composition is 1 to 50 with respect to 100 parts by weight of the rubber component from the viewpoint that the rubber reinforcing effect can be exhibited without deteriorating the dispersibility of the cellulose fiber in the rubber component. About 2 parts by weight is preferable, about 2 to 35 parts by weight is more preferable, and about 3 to 20 parts by weight is more preferable.

Further, the rubber composition of the present invention may further contain sulfur. By containing sulfur, the rubber component can be vulcanized, and a crosslinked structure can be formed between the modified substituent in the modified cellulose fiber and the rubber component.

The sulfur content is preferably about 0.1 to 50 parts by weight, more preferably about 0.5 to 35 parts by weight, and still more preferably about 1 to 20 parts by weight with respect to 100 parts by weight of the rubber component.

The content of the modified cellulose fiber in the rubber component is preferably about 0.1 to 50% by weight, more preferably about 0.5 to 40% by weight, and further preferably about 0.7 to 20% by weight.

4). Method for Producing Rubber Composition The rubber composition of the present invention is produced by a step of mixing modified cellulose fibers and a rubber component.

The method of mixing the modified cellulose fiber and the rubber component is not particularly limited. For example, the modified cellulose fiber and the rubber component are dispersed in a dispersion medium and mixed, whereby the modified cellulose fiber is mixed in the rubber component. This is preferable because it can be uniformly dispersed. Examples of the dispersion medium include halogenated solvents such as methylene chloride, chloroform, and carbon tetrachloride; ketone solvents such as acetone and methyl ethyl ketone (MEK); ethers such as tetrahydrofuran (THF), ethylene glycol, propylene glycol, and polyethylene glycol. And ether solvents such as dimethyl and diethyl compounds; amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; nonpolar solvents such as hexane, heptane, benzene and toluene; and mixed solvents thereof. After mixing the modified cellulose fiber and the rubber component in these dispersion media, the dispersion media are removed by a process such as drying.

In the rubber composition obtained by the above process, the amount of the modified cellulose fiber is preferably about 1 to 50 parts by weight, more preferably about 2 to 35 parts by weight, more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the rubber component. More preferred is about part.

The rubber composition obtained by the above method may further contain a reinforcing filler such as carbon black and silica; a process oil; a wax; an anti-aging agent; a vulcanization aid such as zinc oxide and stearic acid as appropriate. Can do.

Furthermore, when the rubber composition is vulcanized, a vulcanizing agent such as sulfur and a vulcanization accelerator may be further blended. The sulfur content is preferably about 0.1 to 50 parts by weight, more preferably about 0.5 to 35 parts by weight, and still more preferably about 1 to 20 parts by weight with respect to 100 parts by weight of the rubber component.

The method of mixing the modified cellulose fiber with the rubber component and other optional additives is not particularly limited. However, the mixer, blender, twin-screw kneader, kneader, lab plast mill, homogenizer, high-speed homogenizer, high-pressure homogenizer, planetary stirring The method of mixing and stirring with the apparatus which can mix or stir, such as an apparatus and a 3 roll, is mentioned.

The mixing temperature, when sulfur or a vulcanization accelerator is blended, is preferably a temperature at which the rubber component and the modified cellulose fiber do not undergo a crosslinking reaction at the time of mixing. For example, about 70 to 140 ° C. is preferable, and 80 to About 120 ° C. is more preferable.

The rubber composition of the present invention is molded into a desired shape and can be used as a molding material. Examples of the shape of the molding material include sheets, pellets, and powders. A molding material having these shapes can be used to obtain an unvulcanized molded product having a desired shape by using a desired molding machine such as mold molding, injection molding, extrusion molding, hollow molding, and foam molding. .

5. Vulcanizate The vulcanizate of the present invention can be obtained by vulcanizing the rubber composition containing the modified cellulose fiber, the rubber component and sulfur.

The vulcanization temperature is preferably about 150 to 200 ° C, more preferably about 150 to 180 ° C. Examples of the vulcanization method include press vulcanization.

The vulcanizate of the present invention has a modified cellulose fiber dispersed well and uniformly in the rubber component, and further has a crosslinked structure in which the rubber component and the modified cellulose fiber are crosslinked by sulfur. For this reason, a crosslinked structure is formed not only between the molecular chains of the rubber component but also between the rubber component and the modified cellulose fiber. Therefore, the molded article of the present invention has the characteristics that the elastic modulus is high and the linear thermal expansion coefficient is very low.

Specific examples of the molded body of the present invention include, for example, transportation equipment such as automobiles, trains, ships, airplanes, etc .; electrical appliances such as personal computers, televisions, telephones, watches, etc .; mobile communications equipment such as mobile phones; Recycling equipment, video playback equipment, printing equipment, copying equipment, sports equipment, etc .; building materials; office equipment such as stationery, containers, containers, etc., can be applied to members using rubber or flexible plastic It is. In particular, it can be suitably used for tire members such as automobiles that are lightweight and require high elastic modulus and low vibration absorption, and electronic device members that are flexible and require low thermal expansion.

[Example]
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to these.

Reference Example 1 (Preparation of fibrillated cellulose)
Softwood bleached kraft pulp (NBKP) (refiner-treated, manufactured by Oji Paper Co., Ltd.) was dispersed in water to prepare an NBKP water suspension having a solid concentration of 1% by weight.

The obtained aqueous suspension was fibrillated by repeating the fibrillation three times at a disc rotation speed of 1500 rpm using a stone mill grinder (Mellow Industrial Co., Ltd., Serendipeater MKCA6-3). A cellulose (hereinafter also referred to as FC) aqueous suspension (solid content concentration: 1% by weight) was obtained.

SEM image of the obtained FC at a magnification of 20,000 times is shown in FIG. 1A. From FIG. 1A, it was confirmed that the obtained FC was uniformly fibrillated.

Example 1-1 (Preparation of modified FC modified with trans-crotonic acid chloride (hereinafter also referred to as crtFC))
The water in the FC water suspension obtained in Reference Example 1 was replaced with N-methylpyrrolidone (NMP) to prepare an FC suspension with a solid content concentration of 0.5% by weight. To the obtained FC suspension, pyridine is added as a catalyst at a ratio of BR> Q moles per mole of FC glucose units, and TRANS-crotonic acid chloride is added per mole of FC glucose units. 1 mol was added and reacted at 30 ° C. After the completion of the reaction, the obtained product was sufficiently washed with ethanol, and then the solvent was replaced with toluene, and crtFC was suspended in toluene to obtain a 1 wt% crtFC suspension.

The structure of the modified substituent portion in crtFC is shown below.

FIG. 1B shows an SEM image of the obtained crtFC at a magnification of 20,000 times. From FIG. 1B, it was confirmed that the obtained crtFC was uniformly fibrillated.

Further, by FT-IR analysis, DS was obtained from the ratio of the peak intensity of the hydroxyl group and the substituent modified with the modifying agent using FC shown in FIG. 2A as a reference substance. FT-IR was measured by ATR (Attenuated Total Reflection) method using Spectrum 100 manufactured by PerkinElmer. The DS obtained by the above method was 0.4. FIG. 2B shows a spectrum obtained by FT-IR analysis of crtFC.

Example 1-2 (Preparation of modified FC modified with cis-oleoyl chloride (hereinafter referred to as oleFC))
FC modification was carried out in the same manner as in Example 1-1 except that cis-oleoyl chloride was used instead of trans-crotonic acid chloride to obtain oleFC.

The structure of the modified substituent in oleFC is shown below.

FIG. 1C shows an SEM image at a magnification of 20,000 times of the obtained oleFC. From FIG. 1C, it was confirmed that the obtained oleFC was uniformly fibrillated.

Moreover, DS of obtained oleFC was 0.4. The DS was calculated by the same method as in Example 1-1. FIG. 2C shows the spectrum of oleFC obtained by FT-IR analysis.

Example 1-3 (Preparation of modified FC modified with trans, trans-sorbic acid chloride (hereinafter referred to as sorFC))
FC was modified by the same method as in Example 1-1 except that trans, trans-sorbic acid chloride was used instead of trans-crotonic acid chloride to obtain sorFC.

The structure of the modified substituent portion in sorFC is shown below.

FIG. 1D shows an SEM image of the obtained sorFC at a magnification of 20,000 times. From FIG. 1D, it was confirmed that the obtained sorFC was uniformly fibrillated.

Moreover, the DS of the obtained sorFC was 0.4. The DS was calculated by the same method as in Example 1-1. FIG. 2D shows a spectrum of sorFC obtained by FT-IR analysis.

Comparative Example 1-1 (Preparation of modified FC modified with acetyl chloride (hereinafter referred to as acFC))
FC was modified by the same method as in Example 1-1 except that acetyl chloride was used instead of trans-crotonic acid chloride to obtain acFC.

The structure of the modified substituent portion in acFC is shown below.

The SEM image at a magnification of 20,000 times of the obtained acFC is shown in FIG. 1E. From FIG. 1E, it was confirmed that the obtained acFC was uniformly fibrillated.

Moreover, the DS of the obtained acFC was 0.4. The DS was calculated by the same method as in Example 1-1. FIG. 2E shows the spectrum of acFC obtained by FT-IR analysis.

Comparative Example 1-2 (Preparation of modified FC modified with myristoyl chloride (hereinafter referred to as myrFC))
FC was modified by the same method as in Example 1-1 except that myristoyl chloride was used instead of trans-crotonic acid chloride to obtain myrFC.

The structure of the modified substituent portion in myrFC is shown below.

FIG. 1F shows an SEM image of the obtained myrFC at a magnification of 20,000 times. From FIG. 1F, it was confirmed that the obtained myrFC was uniformly fibrillated.

Moreover, DS of myrFC obtained was 0.4. The DS was calculated by the same method as in Example 1-1. FIG. 2F shows a myrFC spectrum obtained by FT-IR analysis.

Comparative Example 1-3 (Preparation of modified FC modified with stearoyl chloride (hereinafter referred to as stFC))
FC was modified by the same method as in Example 1-1 except that stearoyl chloride was used instead of trans-crotonic acid chloride to obtain stFC.

The structure of the modified substituent in stFC is shown below.

The SEM image at a magnification of 20,000 times of the obtained stFC is shown in FIG. 1G. From FIG. 1G, it was confirmed that the obtained stFC was uniformly fibrillated.

Also, the DS of the obtained stFC was 0.4. The DS was calculated by the same method as in Example 1-1. FIG. 2G shows the spectrum of stFC obtained by FT-IR analysis.

Reference Example 2-1 (Preparation of vulcanized rubber)
Formic acid was added to a natural rubber (NR) latex (manufactured by SimDarby Plantation, solid content concentration: 60% by weight), acid coagulated, and dried at 50 ° C. The obtained dried NR was masticated at 90 ° C. for 5 minutes with a three roll, and then 1.5 parts by weight of stearic acid and 2.5 parts by weight of zinc oxide were added to 100 parts by weight of NR and kneaded for 7 minutes. Further, for 100 parts by weight of NR, 3.0 parts by weight of sulfur and 2.0 parts by weight of a vulcanization accelerator (N-cyclohexyl-2-benzothiazolesulfenamide (manufactured by Wako Pure Chemical Industries, Ltd.)) were added. The rubber composition was obtained by kneading for 10 minutes. The obtained rubber composition was hot-pressed at 156 ° C. and vulcanized to obtain a vulcanized rubber sheet.

Reference Example 2-2 (Preparation of vulcanized rubber (dissolved in toluene))
Formic acid was added to NR latex (solid content concentration 60 wt%), acid coagulated, dried at 50 ° C., and toluene was added to the obtained dry NR to prepare a 3 wt% NR solution. The obtained NR solution was cast on a Teflon (registered trademark) petri dish and dried. Additives were added to the obtained dry NR in the same manner as in Reference Example 2-1, followed by vulcanization to obtain a vulcanized rubber sheet.

Reference Example 2-3 (Preparation of vulcanized rubber containing FC)
The 1% by weight FC aqueous dispersion prepared in Reference Example 1 and NR latex (solid content concentration: 60% by weight) were mixed and stirred so that FC contained 5% by weight in the final product. Then, it was acid-coagulated with formic acid and dried at 50 ° C. The resulting rubber composition was masticated at 90 ° C. for 5 minutes with a three roll, and stearic acid and zinc oxide were added at the same blending ratio as in Reference Example 2-1, and kneaded for 7 minutes. Further, sulfur and a vulcanization accelerator were added at the same blending ratio as in Reference Example 2-1, and kneaded for 10 minutes to obtain each rubber composition. The resulting rubber composition was hot-pressed at 156 ° C. and vulcanized to obtain each vulcanized rubber sheet.

Example 2-1 (Preparation of vulcanized rubber compounded with crtFC)
Formic acid was added to NR latex (solid content concentration 60 wt%), acid coagulated, dried at 50 ° C., and toluene was added to the obtained dry NR to prepare a 3 wt% NR solution. To the obtained NR solution, a crtFC dispersion (solid content concentration: 1% by weight) previously dispersed in toluene is added, mixed so as to contain 5% by weight in the final molded product, and stirred for 24 hours. Was prepared. The obtained dispersion was cast into a Teflon (registered trademark) petri dish, dried, and stearic acid and zinc oxide were added at the same blending ratio as in Reference Example 2-1, and kneaded for 7 minutes. Further, sulfur and a vulcanization accelerator were added at the same blending ratio as in Reference Example 2-1, and kneaded for 10 minutes to obtain a rubber composition. Further, the obtained rubber composition was crosslinked by the same method as in Reference Example 2-1 to prepare a vulcanized rubber sheet.

Example 2-2 (Preparation of vulcanized rubber compounded with oleFC)
A vulcanized rubber sheet was obtained in the same manner as in Example 2-1, except that oleFC was used instead of crtFC.

Example 2-3 (Preparation of vulcanized rubber compounded by sorFC)
A vulcanized rubber sheet was obtained in the same manner as in Example 2-1, except that sorFC was used instead of crtFC.

Comparative Example 2-1 (Preparation of vulcanized rubber compounded with acFC)
A vulcanized rubber sheet was obtained in the same manner as in Example 2-1, except that acFC was used instead of crtFC.

Comparative Example 2-2 (Preparation of vulcanized rubber compounded with myrFC)
A vulcanized rubber sheet was obtained in the same manner as in Example 2-1, except that myrFC was used instead of crtFC.

Comparative Example 2-3 (Preparation of vulcanized rubber compounded with stFC)
A vulcanized rubber sheet was obtained in the same manner as in Example 2-1, except that stFC was used instead of crtFC.

Test example 1 (tensile physical properties of vulcanized rubber sheet)
Each vulcanized rubber obtained in Reference Example 2-1, Reference Example 2-2, Reference Example 2-3, Example 2-1, Example 2-2, Comparative Example 2-1, and Comparative Example 2-2 About a sheet | seat, each test piece of the dumbbell type | mold No. 7 type of JISK6251 was produced, and the crosshead speed 200mm / min and span: 20mm using the universal testing machine (the electromechanical universal testing machine 3365 by Instron). Each test piece was pulled under the following conditions to measure a stress-strain curve. The stress-strain curve is shown in FIG. FIG. 3 is a stress-strain curve for each test piece having a (modified) FC content of 5% by weight.

In addition, the elastic modulus of each test piece was measured from the measured stress-strain curve. The evaluation results are shown in Table 1.

<Results and discussion>
From FIG. 3 and Table 1, a vulcanized rubber sheet (Example 2-1) obtained by combining crtFC obtained by crotonoylizing FC with NR, and oleFC obtained by combining oleoylized FC with NR are obtained. It was confirmed that the vulcanized rubber sheet (Example 2-2) had a significantly improved elastic modulus.

Compared to vulcanized rubber sheets obtained by vulcanizing only NR not containing FC (Reference Examples 2-1 and 2-2), vulcanized rubber sheets containing unmodified FC and NR (Reference Example 2) In −3), although the elastic modulus is slightly improved, a remarkable effect is not obtained. About this, by blending FC with high hydrophilicity to NR with high hydrophobicity, FC aggregated in NR and good dispersibility could not be obtained, so sufficient elastic modulus could not be obtained. It is thought that.

Further, a vulcanized rubber sheet obtained by combining acFC obtained by acetylating FC with NR (Comparative Example 2-1), and a vulcanized rubber sheet obtained by combining myrFC obtained by forming myristoyl FC with NR ( In Comparative Example 2-2), the elastic modulus was improved by 2 to 3 times compared to Reference Example 2-3 using unmodified FC, but as in Example 2-1 and Example 2-2. No significant improvement in elastic modulus was observed.

This is thought to be due to the FC being acetylated or myristoylated to impart hydrophobicity to the FC and to improve dispersibility in NR. However, the modified FCs of Comparative Examples 2-1 and 2-2 do not have a double bond, and the substituents in the modified FC do not serve as crosslinking reaction points. Therefore, the modified FCs of Examples 2-1 and 2-2 It is considered that the elastic modulus was not improved.

On the other hand, when the modified substituent has a double bond as in Example 2-1 and Example 2-2, the resulting vulcanized rubber sheet has not only a crosslinking reaction with sulfur in NR. It is considered that a crosslinked structure was formed between NR and modified FC. For this reason, it is considered that the elastic modulus is much improved compared to the vulcanized rubber using the modified FC used in Comparative Example 2-1 and Comparative Example 2-2.

Test example 2 (tensile physical properties of vulcanized rubber sheet)
For each vulcanized rubber sheet obtained in Example 2-2 and Comparative Example 2-3, a stress-strain curve was measured by the same method as in Test Example 1. The stress-strain curve is shown in FIG. FIG. 4 is a stress-strain curve for each test piece having a modified FC content of 5% by weight.

In addition, the elastic modulus of each test piece was measured from the measured stress-strain curve. The evaluation results are shown in Table 2.

<Results and discussion>
4 and Table 2, the vulcanized rubber sheet (Example 2-2) obtained by combining oleFC obtained by oleoylating FC with NR is obtained by combining stFC obtained by stearoylizing FC with NR. Compared with the vulcanized rubber sheet (Comparative Example 2-3), it can be confirmed that the elastic modulus is greatly improved.

From this result, the elastic modulus of the resulting vulcanized rubber sheet is obtained when the modified FC having a substituent having a double bond is used even though the carbon number of the modified substituent in the modified FC is the same. It became clear that it improved.

This is considered to be caused not only by the improvement in dispersibility in NR by using modified FC, but also by the formation of a crosslinked structure between NR and modified FC.

Test Example 3 (Measurement of linear thermal expansion coefficient of vulcanized rubber sheet)
Each vulcanized rubber sheet produced in Reference Example 2-1, Reference Example 2-3, Example 2-1, Example 2-2, and Comparative Examples 2-1 to 2-3 has a size of 40 mm × 4 mm. Each test piece of × 1 mm was prepared, and using a thermal stress strain measuring device (EXSTAR TMA / SS6100 manufactured by SII NanoTechnology Co., Ltd.), a temperature range of 20 to 150 ° C., a heating rate of 5 ° C./min. The thermal expansion (Thermal expansion) at each temperature of each test piece was measured under the conditions, and the linear thermal expansion coefficient (CTE) of each test piece was measured from the obtained value. FIG. 5 shows a graph plotting the thermal expansion with respect to each temperature, and Table 3 shows the linear thermal expansion coefficient of each test piece.

<Results and discussion>
From FIG. 5 and Table 3, a vulcanized rubber sheet (Reference Example 2-2) obtained by vulcanizing NR containing FC and obtained by vulcanizing NR containing modified FC obtained by modifying FC with saturated fatty acid. The vulcanized rubber sheet (Comparative Examples 2-1 to 2-3) has a lower CTE than the vulcanized rubber sheet (Reference Example 2-1) obtained by vulcanizing NR not containing FC. However, sufficient effect is not obtained.

On the other hand, a vulcanized rubber sheet (Example 2-1) obtained by combining crtFC obtained by crotonoylizing FC with NR, and vulcanized rubber sheet obtained by combining oleFC obtained by oleoylizing FC with NR. It can be seen that the vulcanized rubber sheet (Example 2-2) has a significantly lower CTE than the other comparative examples and reference examples in Table 3.

In particular, in Example 2-2 using oleFC, only 5 wt% of oleFC was added, and the CTE of vulcanized rubber of NR not containing FC of Reference Example 2-1 was from 226.1 ppm / ° C. to 18. It dropped dramatically to 6 ppm / ° C.

As with the elastic modulus of Test Examples 1 and 2, it is presumed that the introduction of a side chain having a double bond as a modifying group of the modified FC caused a strong interfacial interaction between the NR and the modified FC due to the crosslinked structure. The

Test example 4
Each vulcanized rubber sheet containing 5% by weight (modified) FC manufactured in Reference Example 2-2, Reference Example 2-3, Example 2-2, and Comparative Example 2-3 has a size of 40 mm × 4 mm × Each test piece of 1 mm was prepared, and dynamic viscoelasticity (DMA) measurement was performed in a tensile mode using a dynamic viscoelasticity measuring apparatus (EXSTAR DMS6100 manufactured by SII Nano Technology Co., Ltd.), frequency 1 Hz, temperature Storage elastic modulus E ′ and tan δ (loss tangent) were measured under the conditions of −100 to 150 ° C. and a temperature increase rate of 3 ° C./min.

FIG. 6 is a graph plotting storage elastic modulus against each temperature, FIG. 7 is a graph plotting tan δ (loss tangent) against each temperature, and Table 4 shows −90 ° C., −20 ° C., 0 ° C., 70 ° C., and The storage elastic modulus of each sample sheet at 150 ° C. is shown. Table 5 shows the temperature of the tan δ peak shown in FIG.

<Results and discussion>
From FIG. 6 and Table 4, the blend of unmodified FC with respect to NR (Reference Example 2-3) and the blend of stFC that does not have an unsaturated bond in modified FC (Comparative Example 2-3) Although the storage elastic modulus is improved, it can be seen that the effect is drastically improved by blending oleoylated oleFC having a double bond (Example 2-2). .

Further, in FIG. 7, it can be seen that the vulcanized rubber sheet of Example 2-2 has a smaller tan δ (loss tangent) than the other comparative examples and reference examples. This is because, by introducing a side chain having a double bond as a modifying group of the modified FC, a strong interfacial interaction occurs between the NR and the FC due to a cross-linked structure, and friction is caused between the NR and the FC at the interface. This is probably because the thermal energy loss has been reduced.

Claims

Hydrogen atoms of some hydroxyl groups in cellulose constituting the cellulose fiber are represented by the formula (1):
-AR 1 (1)
(In Formula (1), R 1 is a hydrocarbon having 3 to 30 carbon atoms having at least one unsaturated bond, and A is a carbonyl group (—CO—) or a single bond (—)).
The modified cellulose fiber substituted by the substituent represented by these.
The modified cellulose fiber according to claim 1, wherein the cellulose fiber is a fibrillated cellulose fiber.
The modified cellulose fiber according to claim 1 or 2, wherein the degree of substitution (DS) is 0.05 to 2.0.
Cellulose fiber is represented by the formula (1 ′):
R 1 -AB (1 ')
(Wherein A is a carbonyl group (—CO—) or a single bond (−), and B is a leaving group)
The manufacturing method of the modified cellulose fiber including the process modified | denatured with the modifier | denaturant represented by these.
The method for producing a modified cellulose fiber according to claim 4, wherein the cellulose fiber is a fibrillated cellulose fiber.
A rubber composition comprising the modified cellulose fiber according to any one of claims 1 to 3 and a rubber component.
The rubber composition according to claim 6, further comprising sulfur.
A vulcanized product obtained by vulcanizing the rubber composition according to claim 7.