JP2018080262A - Rubber composition for tire and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for a tire, in which compatibility between microfibrillated vegetable fiber and a rubber composition is improved while suppressing use of petroleum resource to the minimum, and steering stability and high mileage property can be improved in a good balance, and a tire manufactured by using the rubber composition, and to provide a rubber composition for a tire, in which wear resistance and reinforcing property can be improved by decreasing aggregation of microfibrillated vegetable fiber in the rubber and further increasing dispersibility of the microfibrillated vegetable fiber in the rubber, and a tire manufactured by using the rubber composition.SOLUTION: The rubber composition for a tire comprises a rubber component, microfibrillated vegetable fiber and an emulsifier. The rubber composition for a tire comprises a rubber component, microfibrillated vegetable fiber having an average fiber diameter of 1 nm or more and less than 20 nm.SELECTED DRAWING: None

Description

The present invention relates to a tire rubber composition and a tire using the rubber composition.

It has been conventionally known that physical properties of a rubber composition can be improved by blending a microfibrillated plant fiber such as cellulose fiber as a filler with the rubber composition. However, since the microfibrillated plant fiber has poor compatibility with the rubber component and has low dispersibility, a sufficient improvement effect may not be obtained even when blended with the rubber composition.

Patent Document 1 proposes a technique for improving the compatibility with a rubber component by chemically treating the surface of cellulose fibers to introduce a hydrophobic group. Patent Documents 2 and 3 propose a technique for improving compatibility with a rubber component by chemically treating a pulp with a silane coupling agent having an amino group or a sulfur atom. However, since these methods all require a chemical reaction process, a simpler method is required.

In addition, a method for improving the dispersibility of silica in rubber by using a lecithin of amphiphilic phospholipid in combination with a specific silane coupling agent or the like has been proposed (for example, see Patent Document 4). Stable dispersion of carbon black when producing a wet masterbatch by solid-liquid separation and dehydration of the coagulated product slurry obtained by mixing and coagulating rubber latex and carbon black slurry in which carbon black is dispersed in water It is disclosed that a dispersant such as saponin may be added in order to prepare a carbon black slurry (see, for example, Patent Document 5), but those used in combination with cellulose fibers are not disclosed.

Conventionally, rubber has been reinforced with short fibers such as aramid and cellulose and crystalline polymers such as syndiotactic polybutadiene to improve hardness and modulus, for example, to improve the complex elastic modulus (E ^* ) at 70 ° C. A technique for improving steering stability is known (see, for example, Patent Document 6). However, even when the elastic modulus is improved, all other performances required for the tire other than the handling stability are not necessarily improved.

Patent Document 6 proposes a rubber composition comprising a diene rubber component, starch and cellulose for the purpose of providing a rubber composition having excellent abrasion resistance, and also proposes using bacterial cellulose as the cellulose. ing. However, the technique of Patent Document 6 has a problem that the breaking property is poor due to poor compatibility between rubber and cellulose, and the energy loss at the interface between rubber and cellulose is large.

Patent Document 7 discloses a rubber composition obtained by blending finely divided cellulose fibers prepared from natural plant fibers with a diene rubber as a rubber composition capable of achieving both low resilience and rigidity (steering stability). Yes. However, the technique of Patent Document 7 has room for improvement in terms of obtaining rigidity and reinforcing properties commensurate with the blended amount of cellulose fibers because the fiber length of the cellulose fibers is short due to its production method.

Moreover, in patent document 8, the moisture content of the residue produced in the fermentation process of organic substance shall be 5-90 mass%, a particle size shall be 0.02-600 micrometers, and such a residue is mix | blended with an elastomer component as an alternative raw material. It is possible to provide an environment-friendly elastomer composition that can be produced at low cost without using a complicated production process, without significantly reducing physical properties as compared with an elastomer composition that does not use an alternative raw material. By using such an elastomer composition, it is said that a tire having a low environmental load during production can be provided.

JP 2009-84564 A JP 2011-231204 A JP 2011-231205 A JP 2014-11116 A1 JP2015-110722A JP 2005-133025 A JP-A-2005-75856 International Publication No. 2010/050505

The present invention solves the above problems and improves the compatibility between the microfibrillated plant fiber and the rubber component while suppressing the use of petroleum resources as much as possible, and can improve the steering stability and fuel efficiency in a well-balanced manner. It aims at providing the tire produced using the composition and this rubber composition.

In addition, as described above, rubber compositions containing organic substances such as cellulose have been developed. However, the dispersibility of these compounds in rubber is not yet sufficient, and the physical properties of the rubber composition are not satisfactory. There was room for further improvement.

The present invention also solves the above-mentioned problems, reduces the formation of agglomerates of microfibrillated plant fibers in the rubber, and further improves the dispersibility of the microfibrillated plant fibers in the rubber, thereby improving the wear resistance. Another object of the present invention is to provide a tire rubber composition capable of improving the reinforcing property, and a tire produced using the rubber composition.

As described in paragraph [0019] of Patent Document 4, in general, when lecithin is simply blended, lecithin does not have a silica-polymer coupling function, so that the rubber component such as a polymer can be used. It is known that the silica dispersibility of the resin decreases. On the other hand, as a result of intensive studies, the present inventors have found that when an emulsifier such as lecithin is used in combination with microfibrillated plant fibers, the dispersibility of the microfibrillated plant fibers in the rubber component is improved, and the present invention is completed. It came to.

The present invention relates to a tire rubber composition comprising a rubber component, microfibrillated plant fibers, and an emulsifier. Hereinafter, this invention is referred to as a first invention of the present invention, and is also referred to as a first invention.

The rubber component preferably contains at least one selected from the group consisting of natural rubber, modified natural rubber, synthetic rubber, and modified synthetic rubber.

The microfibrillated plant fiber is preferably cellulose microfibril.

The average fiber diameter of the microfibrillated plant fiber is preferably 1 to 100 nm.

The content of the microfibrillated plant fiber is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

The content of the emulsifier is preferably 0.1 to 500 parts by mass with respect to 100 parts by mass of the solid content of the microfibrillated plant fiber.

The emulsifier is preferably derived from nature, and more preferably lecithin and / or saponin.

The first aspect of the present invention also relates to a tire manufactured using the tire rubber composition.

The present invention also relates to a tire rubber composition comprising a rubber component and microfibrillated plant fibers, wherein the microfibrillated plant fibers have an average fiber diameter of 1 nm or more and less than 20 nm. Hereinafter, this invention is referred to as a second invention of the present invention and is also referred to as a second invention.

The microfibrillated plant fiber is preferably cellulose microfibril.

The content of the microfibrillated plant fiber is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The microfibrillated plant fiber also preferably has a structure in which hydrogen atoms of some hydroxyl groups in cellulose microfibrils are substituted with a carboxyl group-containing group of a cyclic carboxylic acid anhydride.

The second aspect of the present invention also relates to a tire produced using the tire rubber composition.

The tire is preferably a studless tire.

According to 1st this invention, it is a rubber composition for tires containing a rubber component, microfibrillated plant fiber, and an emulsifier, and improves the compatibility of a microfibrillated plant fiber and a rubber component by adding an emulsifier. Therefore, it is possible to provide a tire that synergistically improves the performance balance between steering stability and low fuel consumption. Further, since the microfibrillated plant fiber is a material that does not use petroleum as a raw material, the amount of petroleum resources used can be reduced and the environment can be considered.

According to the second aspect of the present invention, since the rubber composition for a tire includes a rubber component and microfibrillated plant fibers, and the average fiber diameter of the microfibrillated plant fibers is 1 nm or more and less than 20 nm, Rubber composition for tires with improved wear resistance and reinforcing properties due to the reduced dispersibility of microfibrillated plant fibers in rubber by reducing the formation of aggregated plant fibers in rubber And a tire with improved wear resistance and reinforcement, produced using the rubber composition. Further, since the microfibrillated plant fiber is a material that does not use petroleum as a raw material, the amount of petroleum resources used can be reduced and the environment can be considered.

In the present specification, the first invention and the second invention are collectively referred to as the present invention. First, the first present invention will be described, and then the second present invention will be described.
(First invention)
The rubber composition of the first invention includes a rubber component, microfibrillated plant fiber, and an emulsifier. By adding an emulsifier, the compatibility between the rubber component and the microfibrillated plant fiber is improved, and both rigidity and elongation at break can be achieved while suppressing an increase in energy loss. Therefore, by using the rubber composition for a tire, it is possible to achieve both rigidity and elongation at break while maintaining good fuel efficiency, and a remarkable and synergistic balance of performance between fracture characteristics, handling stability and fuel efficiency. Improved tires can be provided. This effect is presumed to be due to the emulsifying action of the emulsifier.

Moreover, since the microfibrillated plant fiber is a material that does not use petroleum as a raw material (resource other than petroleum), the amount of petroleum resource used can be reduced.

The method for producing the rubber composition of the first aspect of the present invention is not particularly limited as long as the rubber component, the microfibrillated plant fiber, and the emulsifier are mixed. For example, the step of mixing the microfibrillated plant fiber and the emulsifier A production method including (I) and step (II) in which a rubber component is added to the mixture obtained in step (I) and further mixed is preferable.

(Process (I))
In step (I), the microfibrillated plant fiber and the emulsifier are mixed. In this way, by mixing the microfibrillated plant fiber and the emulsifier in advance, when the rubber component and the mixture obtained in the step (I) are mixed in the step (II) described later, the microfibrillation is performed in the rubber component. Plant fibers can be sufficiently dispersed. In the step (I), it is preferable that the microfibrillated plant fiber and the emulsifier are mixed in a solvent such as water because the microfibrillated plant fiber and the emulsifier can be easily mixed.

As the microfibrillated plant fiber used in the step (I), cellulose microfibril is preferable from the viewpoint that good reinforcing properties can be obtained. Cellulose microfibrils are not particularly limited as long as they are derived from natural products, for example, resource biomass such as fruits, cereals, root vegetables, wood, bamboo, hemp, jute, kenaf, and pulps obtained using these as raw materials, Paper, cloth, crop waste, waste biomass such as food waste and sewage sludge, unused biomass such as rice straw, straw and thinned wood, as well as cellulose derived from sea squirts and acetic acid bacteria, etc. It is done.

Although it does not specifically limit as a manufacturing method of microfibrillated plant fiber, For example, after chemically processing the raw material of the said cellulose microfibril with chemical | medical agents, such as sodium hydroxide, a refiner, a twin screw kneader (double screw extruder), two Examples thereof include a method of mechanically grinding or beating using a shaft kneading extruder, a high-pressure homogenizer, a medium stirring mill, a stone mill, a grinder, a vibration mill, a sand grinder or the like. In this method, since lignin is separated from the raw material by chemical treatment, microfibrillated plant fibers substantially free of lignin are obtained. In addition, as another method, a method of subjecting the raw material of the cellulose microfibril to an ultra-high pressure treatment may be mentioned.

The average fiber diameter of the microfibrillated plant fiber is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 50 nm or less, particularly preferably, from the viewpoint of a good balance between the rubber reinforcing effect, the elastic modulus, and the elongation at break. Is 30 nm or less. The lower limit of the average fiber diameter of the microfibrillated plant fiber is not particularly limited, but when a solvent such as water is used in step (I), 1 nm or more is preferable from the viewpoint of suppressing workability deterioration due to deterioration of drainage. It is preferably 2 nm or more, more preferably 4 nm or more, and particularly preferably 10 nm or more.

The average fiber length of the microfibrillated plant fiber is preferably 5 mm or less, more preferably 1 mm or less, preferably 1 μm or more, more preferably 10 μm or more, still more preferably 30 μm or more, and particularly preferably 50 μm or more. . When the average fiber length is in such a range, the effect of the first aspect of the present invention can be obtained more suitably.

The average fiber diameter and average fiber length of microfibrillated plant fibers are image analysis of scanning electron micrographs, image analysis of transmission micrographs, analysis of X-ray scattering data, pore electrical resistance method (Coulter principle method), etc. Can be measured by.

In step (I), an aqueous dispersion of microfibrillated plant fibers is preferably used. Thereby, microfibrillated plant fiber and an emulsifier can be mixed uniformly in a short time. The content (solid content) of microfibrillated plant fibers in the aqueous dispersion of microfibrillated plant fibers is preferably 2 to 40% by mass, more preferably 5 to 30% by mass.

Next, the emulsifier used in the step (I) will be described.
The emulsifier is not particularly limited. For example, anionic emulsifier, cationic emulsifier, nonionic emulsifier, dispersion stabilizer, sucrose fatty acid ester, polysorbate, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, lecithin And lecithin derivatives (for example, lysolecithin), saponin, saponin derivatives, casein, casein derivatives, and the like. As said emulsifier, these may be used independently and 2 or more types may be used together.

Examples of the anionic emulsifier include sodium polyoxyethylene lauryl ether sulfate, sodium alkylbenzene sulfonate, sodium alkyl sulfate, sodium naphthalene sulfonate formalin condensate, dialkyl sulfosuccinate, potassium rosinate, ammonium oleate, and sodium oleate. And fatty acid soaps such as potassium oleate, sodium laurate, and potassium stearate.

Examples of the cationic emulsifier include alkyl trimethyl ammonium chloride, alkyl amine acetate, polyoxyethylene alkyl amine acetate, and the like.

Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene sorbitan alkylate, oxyethylene oxypropylene block copolymer, polyglycerin ester and the like. It is done.

Examples of the dispersion stabilizer include polymer dispersants such as polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, sodium polyacrylate, sodium polymethacrylate, and styrene maleic anhydride copolymer. Etc.

Examples of the fatty acid of the sucrose fatty acid ester include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, erucic acid, oleic acid, and linolenic acid.

Examples of the polyglycerin fatty acid ester include, for example, hardened palm oil monoglyceride, oleic acid monoglyceride, rapeseed hardened oil fatty acid mono-diglyceride, self-emulsifying stearic acid mono-diglyceride, oleic acid mono-diglyceride, caprylic acid monoglyceride, lauric acid monoglyceride, Capric acid monoglyceride, caprylic acid mono-diglyceride, caprylic acid diglyceride, mono-dioleic acid diglycerin, mono-distearic acid diglycerin, monostearic acid diglycerin, pentaoleic acid decaglycerin, pentastearic acid decaglycerin, dekaoleic acid decaglycerin , Decastearic acid decaglycerin, trioleic acid pentaglycerin, hexastearic acid pentaglycerin, monolauric acid decaglycerin Monolaurate decaglycerin, monomyristic acid decaglycerin, monooleic acid decaglycerin, monostearic acid decaglycerin, monostearic acid decaglycerin preparation, distearic acid decaglycerin, monolauric acid pentaglycerin, monomyristic acid pentaglycerin, monooleic acid penta Glycerin, pentaglyceryl monostearate, condensed glycinic acid tetraglycerin, condensed ricinoleic acid hexaglycerin, condensed ricinoleic acid pentaglycerin, 50% acetylated stearic acid monoglyceride (acetic acid MG), glyceryl lactate monostearate, glyceryl monostearate , Glycerol monooleate, glyceryl succinate monostearate, diacetyltartaric acid monostearate glycerin , Sorbitan monostearate, sorbitan monooleate, propylene glycol monostearate, propylene glycol monooleate, enzymatically decomposed soybean lecithin formulations (lecithin content 33%), and the like.

Other examples include zwitterionic emulsifiers such as lauryl dimethylamine oxide, and inorganic compounds such as tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and barium carbonate.

Among these emulsifiers, naturally derived emulsifiers such as lecithin, saponin, casein, sucrose fatty acid ester, polyglycerin fatty acid ester are preferable. Naturally-derived emulsifiers are materials that do not use petroleum as a raw material (non-petroleum resources), so the use of naturally-derived emulsifiers can reduce the amount of petroleum resources used and consider the environment. it can.
More preferred are lecithin, saponin, casein and polyglycerin fatty acid ester, still more preferred are lecithin, saponin and casein, and particularly preferred are lecithin and saponin. That is, the emulsifier is lecithin and / or saponin, which is one of the preferred embodiments of the first invention.

In the first aspect of the present invention, lecithin is also called phosphatidylcholine, means a lipid mixture mainly composed of various phospholipids, is a main component constituting a cell membrane and the like, and is a natural component such as soybean and egg yolk. It is contained in many animals and plants. The phospholipid is not particularly limited as long as it has a phosphate ester structure. The phosphate ester structure refers to a structure in which part or all of the three hydrogen atoms of phosphoric acid (O = P (OH) ₃ ) are substituted with an organic group. Although it will not specifically limit if it is lecithin derived from animals and plants, The lecithin derived from soybean is preferable at the point from which the effect of 1st this invention is acquired favorably.

The origin of the lecithin is not particularly limited, and examples thereof include purified lecithin obtained by extraction from the above-mentioned animals and plants by a known purification method and the like, and industrially, a large amount is obtained by extraction from egg yolk or soybean. Has been produced.

The purified lecithin includes, for example, glycerophospholipids based on glycerol such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidic acid, and derivatives thereof, sphingomyelin and derivatives thereof. The main component is a phospholipid such as sphingophospholipid having a sphingosine base as a basic skeleton, and also includes components such as triglyceride, glycolipid, sterol, tocopherol and carbohydrate.

The degree of purification of the lecithin is not particularly limited, and may be crude lecithin as it is extracted from the animals and plants, or may be purified lecithin from which components other than the phospholipid are removed. The highly purified lecithin (high-purity lecithin) having a phospholipid content of 90% by mass or more, in which components other than the phospholipids are further removed, is preferred in that the effect of the present invention can be favorably obtained. Is more preferable, and 96 mass% or more is still more preferable.
In addition, the phospholipid content contained in lecithin can be determined by measuring the acetone insoluble matter in the lecithin.

In addition to the above-mentioned purified lecithin, fractionated lecithin from which impurities such as oil have been removed to increase the specific phospholipid content, single strands by enzymatic degradation, degradation of impurities by enzymatic partial degradation treatment, phospholipid concentration Modified lecithins such as enzyme-degraded (lyso) lecithin that has been changed or hydrogenated lecithin that has been subjected to hydrogenation treatment can also be used.

Examples of commercially available products of lecithin include Phospholipon 20 manufactured by Lipoid, Reion P manufactured by Riken Vitamin Co., SLP-White manufactured by Sakai Oil Co., Ltd., and Malmetic 300 manufactured by Lucas Meyer Cosmetics. .

In the first aspect of the present invention, saponin is a general term for glycosides composed of sapogenin and a sugar, and the sapogenin may be a steroid or a triterpene, and the sugar is glucose, galactose, pentose or methylpentose. It's okay.

Examples of the saponins include those containing sterol glycosides widely distributed in plants, for example, fruits, leaves of various plants such as yucca, soapflower, agave, tobacco, daylily, soybean, ginseng, asparagus, ginkgo It can be produced and isolated from various parts such as seeds and roots by a known method.

Examples of the saponins include triterpenoid saponins and steroid saponins. Among these, triterpenoid saponins are preferable.

In the step (I), it is preferable to blend each component so as to have a content described later in the rubber composition of the first invention. Thereby, the balance of a rubber reinforcement effect, breaking elongation, and energy loss becomes favorable.

The method of mixing each component in the step (I) is not particularly limited, and for example, a general method such as a propeller type stirring device, a homogenizer, a rotary stirring device, an electromagnetic stirring device, manual stirring, or the like can be used.

(Process (II))
In step (II), the rubber component is added to the mixture obtained in step (I) and further mixed. In this step, the microfibrillated plant fiber and the rubber component are combined.

The rubber component used in step (II) preferably contains at least one selected from the group consisting of natural rubber, modified natural rubber, synthetic rubber and modified synthetic rubber. Examples of the rubber component include diene rubbers. Specifically, natural rubber (NR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber (IR), acrylonitrile. -Butadiene rubber (NBR), acrylonitrile-styrene-butadiene copolymer rubber, chloroprene rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene And modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber, and deproteinized natural rubber. Examples of rubber components other than diene rubbers include butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene copolymer rubber, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber, and the like. It is done. These rubber components may be used alone, or may be used by blending two or more kinds, or may be condensed or modified. What is necessary is just to mix | blend suitably also in the blend ratio in the case of blending according to various uses. Among them, NR, BR, SBR, IR, IIR and ENR are preferable from the viewpoint of versatility and cost, and good workability when mixed with microfibrillated plant fibers. From the viewpoint that the amount of petroleum resources used can be reduced and the environment can be taken into consideration, NR and ENR, which are materials derived from resources other than petroleum, are more preferable. Especially, when NR is used, the effect of the first aspect of the present invention can be obtained more suitably.
Moreover, it is preferable to use the said rubber component in the state of a latex from the point that a microfibril plant fiber and a rubber component can be mixed uniformly in a short time. In rubber latex, content (solid content) of a rubber component becomes like this. Preferably it is 30-80 mass%, More preferably, it is 40-70 mass%.

In addition, regarding the above synthetic rubber, when it is assumed that petroleum resources will be depleted in the future, do not use a monomer derived from fossil fuel, or use a synthetic rubber obtained by using a renewable raw material as a monomer. You can also. For example, in the case of butadiene rubber, a synthetic rubber produced from such a bio-derived raw material can be obtained by a method of polymerizing the butadiene by reacting bioethanol with a catalyst.

In the step (II), it is preferable to blend each component so as to have a content described later in the rubber composition of the first invention. Thereby, the balance of the rubber reinforcing effect, elongation at break and energy loss becomes good, and the yield and workability of various materials become good.

The method of mixing each component in step (II) is not particularly limited, and the same method as in step (I) can be used. Similarly to step (I), in step (II), it is preferable to mix each component in a solvent such as water.

By the steps (I) and (II), a master batch in which microfibrillated plant fibers are uniformly dispersed in a rubber matrix can be prepared. In addition, when the mixture obtained by process (II) is a slurry state, a masterbatch can be prepared by kneading | mixing with the Banbury mixer etc. after coagulating and drying the said mixture by a well-known method.

The rubber composition of the first present invention is produced by a known method using the master batch. For example, it can be produced by a method in which the masterbatch and other components are kneaded with a Banbury mixer, a kneader, an open roll or the like and then vulcanized. Other compounding agents include, for example, reinforcing agents (carbon black, silica, etc.), silane coupling agents, vulcanizing agents, stearic acid, vulcanization accelerators, vulcanization acceleration aids, oils, cured resins, waxes, aging An inhibitor etc. are mentioned.

In the rubber composition of the first invention, the content of NR is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass in 100% by mass of the rubber component. If it is in the said range, the effect of 1st this invention will be acquired suitably.

In the rubber composition of the first aspect of the present invention, the content of the microfibrillated plant fiber is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass with respect to 100 parts by mass of the rubber component. It is preferably 100 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. If it is in the said range, a microfibrillated plant fiber can be disperse | distributed favorably and a destructive characteristic, steering stability, and low fuel consumption can be improved with good balance.

In the rubber composition of the first invention, the content of the emulsifier is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the solid content of the microfibrillated plant fiber. More preferably, it is 1 part by mass or more, more preferably 10 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 500 parts by mass or less, more preferably 400 parts by mass or less, still more preferably 300 parts by mass. Part or less, particularly preferably 250 parts by weight or less. If it is in the said range, microfibrillated plant fiber can be disperse | distributed favorably and the performance balance of a fracture characteristic, steering stability, and fuel-consumption property can be improved significantly.

The content of non-petroleum resources in 100% by mass of the rubber composition is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 97% by mass or more. According to the first aspect of the present invention, since the above-described components are used, even when the content of non-petroleum resources is increased, destructive characteristics, steering stability, and low fuel consumption can be obtained in a well-balanced manner.
The content of non-petroleum resources, the abundance of carbon isotope ^{14 C} in carbon dioxide in the exhaust gas by burning rubber composition was measured, the ^{14 C} of resources other than petroleum derived materials and petroleum-resource-derived material It can be discriminated by a method such as comparing differences.

The rubber composition of the first invention can be used for a tire member. Thus, the tire produced using the tire rubber composition of the first invention is also one of the first inventions. Examples of the tire include a pneumatic tire, a studless tire (winter tire), a run flat tire, and the like.

The tire of the first aspect of the present invention is manufactured by a known method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of each member of the tire at an unvulcanized stage and molded by a normal method on a tire molding machine. After forming an unvulcanized tire by heating, the tire can be manufactured by heating and pressing in a vulcanizer.

When the tire of the first invention is a pneumatic tire, the members to which the rubber composition of the first invention can be applied include sidewalls, base treads, bead apex, clinch apex, inner liner, under Examples include treads, breaker toppings, prite toppings, treads and the like, and among them, it can be suitably used for treads and sidewalls.

When the tire of the first aspect of the present invention is a pneumatic tire, it can be suitably used for passenger cars, trucks, buses and the like.

Next, the case where the tire of the first aspect of the present invention is a studless tire will be described.

The rubber composition of the first present invention contains a rubber component, microfibrillated plant fiber, and an emulsifier. By adding the emulsifier, the compatibility between the rubber component and the microfibrillated plant fiber is improved. Good rigidity can be obtained while suppressing an increase in energy loss. Therefore, when the rubber composition of the first aspect of the present invention is applied to each member of the studless tire, it is possible to provide a studless tire that is remarkably and synergistically improved in the performance balance of on-ice performance, steering stability, and low fuel consumption. This effect is presumed to be due to the emulsifying action of the emulsifier.

When the rubber composition of the first invention is applied to each member of a studless tire, the same rubber component as described above can be used as the rubber component. It is preferable that natural rubber (NR) and butadiene rubber (BR) are included from the viewpoint of imparting performance.

The content of natural rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 40% by mass or more. Further, the content is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less, and particularly preferably 60% by mass or less. If the content of the natural rubber is in such a range, the performance on ice, the handling stability and the low fuel consumption can be improved in a well-balanced manner.

The content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 40% by mass or more from the viewpoint of exerting necessary snow and ice performance. In addition, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 60% by mass or less, from the viewpoint of workability.

When the rubber composition of the first aspect of the present invention is applied to each member of a studless tire, examples of the microfibrillated plant fiber used include those described above.

When the rubber composition of the first invention is applied to each member of the studless tire, the content of the microfibrillated plant fiber is preferably 1 part by mass or more, more preferably 3 parts per 100 parts by mass of the rubber component. It is at least 5 parts by mass, more preferably at least 5 parts by mass, preferably at most 100 parts by mass, more preferably at most 30 parts by mass, even more preferably at most 25 parts by mass, particularly preferably at most 20 parts by mass. Within the above range, the microfibrillated plant fiber can be well dispersed and the performance on ice, the handling stability and the low fuel consumption can be improved in a well-balanced manner.

When applying the rubber composition of the first invention to each member of the studless tire, the content of the emulsifier is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the solid content of the microfibrillated plant fiber. More preferably 0.5 parts by mass or more, further preferably 1 part by mass or more, still more preferably 10 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 500 parts by mass or less, more preferably 400 parts by mass. It is not more than part by mass, more preferably not more than 300 parts by mass, particularly preferably not more than 250 parts by mass. Within the above range, the microfibrillated plant fiber can be dispersed well, and the performance balance of on-ice performance, steering stability and low fuel consumption can be remarkably improved.

When the rubber composition of the first invention is applied to each member of a studless tire, the rubber composition of the first invention preferably contains oil as a plasticizer. As a result, the hardness can be adjusted to an appropriate low level and good performance on snow and ice can be obtained. Although it does not specifically limit as oil, For example, process oil, vegetable oil, or its mixture can be used. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Of these, paraffinic process oil is preferably used.

The oil content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and still more preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component. Further, the content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is in the said range, performance on ice can be improved more.

When the rubber composition of the first invention is applied to each member of a studless tire, the content of non-petroleum resources in 100% by mass of the rubber composition is preferably 70% by mass or more, more preferably 80% by mass or more. More preferably, it is 97% by mass or more. According to 1st this invention, since the above-mentioned component is used, even if it is a case where content of resources other than petroleum is made high, performance on ice, steering stability, and low fuel consumption can be obtained with good balance.

The rubber composition of the first invention includes cap tread, base tread, under tread, clinch apex, bead apex, sidewall, breaker, edge band, full band, breaker cushion rubber, carcass cord covering rubber, etc. It can be used for each member of a studless tire, and can be particularly suitably used for a tread.

A studless tire having a member manufactured using the rubber composition of the first invention is manufactured by a normal method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of each member (tread, etc.) at an unvulcanized stage and molded on a tire molding machine by a normal method. And it bonds together with another tire member, and forms an unvulcanized tire. The unvulcanized tire can be heated and pressurized in a vulcanizer to produce the studless tire of the first invention.

The studless tire having a member produced using the rubber composition of the first invention can be suitably used for passenger cars, trucks / buses (heavy-duty vehicles) and the like.

(Second invention)
The rubber composition of the second present invention contains a rubber component and microfibrillated plant fibers having an average fiber diameter of 1 nm or more and less than 20 nm. As the microfibrillated plant fiber to be blended in the rubber composition, an average fiber diameter of 1 nm or more and less than 20 nm and a fiber having a high degree of fibrillation and a small average fiber diameter are used so that the microfibrillated plant fiber is aggregated in rubber. The present inventors have found for the first time that this is reduced and the dispersibility of the microfibrillated plant fiber in the rubber is further increased. Therefore, the dispersibility of the microfibrillated plant fiber in the rubber can be further improved by blending the microfibrillated plant fiber having an average fiber diameter of 1 nm or more and less than 20 nm into the rubber composition. And the reinforcement property can be improved. Therefore, by using the rubber composition for a tire, it is possible to provide a tire with improved wear resistance and reinforcement.

Moreover, since the microfibrillated plant fiber is a material that does not use petroleum as a raw material (resource other than petroleum), the amount of petroleum resource used can be reduced.

<Rubber component>
As the rubber component used in the second present invention, general rubbers used in the rubber industry can be used. For example, natural rubber (NR), epoxidized natural rubber (ENR), hydrogenated natural rubber , Modified natural rubber such as deproteinized natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene rubber, styrene isoprene butadiene rubber (SIBR), isoprene butadiene rubber, acrylonitrile butadiene rubber It is preferable to use a diene rubber such as (NBR), acrylonitrile styrene butadiene rubber, chloroprene rubber (CR), or chlorosulfonated polyethylene. The rubber component may contain a rubber component other than the diene rubber. Examples of the other rubber component include butyl such as halogenated butyl rubber (X-IIR) and butyl rubber (IIR). Examples of the rubber include ethylene rubber, ethylene-propylene copolymer rubber, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, and urethane rubber.
These rubber components may be used alone, or may be used by blending two or more kinds, or may be condensed or modified. What is necessary is just to mix | blend suitably also in the blend ratio in the case of blending according to various uses.

As the rubber component, NR, BR, SBR, IR are particularly advantageous from the viewpoints of versatility and cost, and good workability when mixed with microfibrillated plant fibers. IIR and ENR are preferable, and NR and ENR, which are materials derived from non-petroleum resources, are more preferable from the viewpoint of reducing the amount of petroleum resources used and considering the environment. Especially, when NR is used, the effect of the second aspect of the present invention can be obtained more suitably. Further, when NR and BR are used in combination as the rubber component, the effect of the second aspect of the present invention can be obtained more preferably.

In addition, regarding the above-mentioned diene rubber, when assuming the future depletion of petroleum resources, do not use a fossil fuel-derived monomer, or use a diene rubber obtained using a renewable bio-derived raw material as a monomer. You can also For example, in the case of a butadiene rubber, a diene rubber produced from such a bio-derived raw material can be obtained by a method of polymerizing the butadiene by reacting bioethanol with a catalyst.

It does not specifically limit as said natural rubber (NR), For example, what is common in rubber industry, such as SIR20, RSS # 3, TSR20, can be used.

The butadiene rubber (BR) is not particularly limited, and those commonly used in the tire industry can be used. For example, high cis such as BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., and BR150B. Butadiene rubber with content, modified butadiene rubber such as BR1250H manufactured by Nippon Zeon Co., Ltd., butadiene rubber containing syndiotactic polybutadiene crystals such as VCR412 and VCR617 manufactured by Ube Industries, Ltd., BUNA manufactured by LANXESS A butadiene rubber or the like synthesized using a rare earth element-based catalyst such as -CB25 can be used. These BR may use 1 type and may use 2 or more types together.

The cis content of BR is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 97% by mass or more.
In the present specification, the cis content of BR (cis 1,4 bond content) can be measured by infrared absorption spectrum analysis.

The content of each rubber in the rubber component is not particularly limited and can be set as appropriate. The content of natural rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10%. It is at least 20% by mass, more preferably at least 20% by mass, even more preferably at least 80% by mass, particularly preferably at least 90% by mass. Moreover, the upper limit of this content is not specifically limited, You may be 100 mass%.

The content of butadiene rubber when natural rubber and butadiene rubber are used in combination as the rubber component is, for example, preferably 20% by mass or more, more preferably 30% by mass or more, and 100% by mass in 100% by mass of the rubber component. % Or more is more preferable. On the other hand, 80 mass% or less is preferable, 70 mass% or less is more preferable, and 60 mass% or less is still more preferable.

<Microfibrillated plant fiber>
As the microfibrillated plant fiber used in the second aspect of the present invention, cellulose microfibril is preferable from the viewpoint that better reinforcing properties can be obtained. Cellulose microfibrils are not particularly limited as long as they are derived from natural products, for example, resource biomass such as fruits, cereals, root vegetables, wood, bamboo, hemp, jute, kenaf, and pulps obtained using these as raw materials, Paper, cloth, crop waste, waste biomass such as food waste and sewage sludge, unused biomass such as rice straw, straw and thinned wood, as well as cellulose derived from sea squirts and acetic acid bacteria, etc. It is done.
In the present specification, the cellulose microfibril means a cellulose fiber in which cellulose molecules are aggregated in a bundle to form a microfibril.

The average fiber diameter of the microfibrillated plant fiber is 1 nm or more and less than 20 nm. Higher strength and elasticity when compounded with rubber components due to the fact that microfibrillated plant fibers in rubber are reduced to agglomerates and the dispersibility of microfibrillated plant fibers in rubber is further increased. The average fiber diameter is preferably 18 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less, from the viewpoint that the ratio can be obtained and the effects of the second invention can be exhibited more remarkably. 8 nm or less is particularly preferable. Further, from the viewpoint of the strength of the rubber composition after blending, it is preferably 2 nm or more, more preferably 3 nm or more, and further preferably 4 nm or more.

The average fiber length of the microfibrillated plant fiber is preferably 5 mm or less, more preferably 1 mm or less, preferably 1 μm or more, more preferably 10 μm or more, still more preferably 30 μm or more, and particularly preferably 50 μm or more. is there. When the average fiber length is in such a range, the effect of the second aspect of the present invention can be obtained more suitably.

The average fiber diameter and average fiber length of the microfibrillated plant fiber are image analysis of scanning atomic force micrograph, image analysis of scanning electron micrograph, image analysis of transmission micrograph, analysis of X-ray scattering data, It can be measured by the pore electrical resistance method (Coulter principle method) or the like.

The content of the microfibrillated plant fiber is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 100 parts by mass with respect to 100 parts by mass of the rubber component. It is not more than 50 parts by mass, more preferably not more than 50 parts by mass, still more preferably not more than 30 parts by mass, still more preferably not more than 25 parts by mass, particularly preferably not more than 20 parts by mass. By setting it within the above range, the dispersibility of the microfibrillated plant fiber in the rubber can be further enhanced, and the effect of the second invention can be more suitably obtained.

The method for producing the microfibrillated plant fiber is not particularly limited as long as the average fiber diameter is 1 nm or more and less than 20 nm, and the degree of fibrillation is large and the average fiber diameter is small. For example, the raw material of the cellulose microfibril is, for example, A preferred method is to treat the enzyme with an enzyme. In this method, since the fiber of the raw material is decomposed and defibrated by the enzyme treatment, the degree of fiber defibration can be increased as compared with the conventional method in which the enzyme treatment is not performed. Thus, it is also one of the preferred embodiments of the second invention that the microfibrillated plant fiber is obtained by treating the cellulose microfibril raw material with an enzyme.

As a method for treating the raw material of cellulose microfibril with an enzyme, a method of enzyme treatment usually performed, such as allowing an enzyme to act on the raw material while appropriately shaking the solution containing the raw material of cellulose microfibril and the enzyme, is used. As an enzyme used in the method of treating the cellulose microfibril raw material with an enzyme, an enzyme that acts on the raw material of cellulose microfibril and can be decomposed, defibrated, or the like can be used. Examples thereof include cellulases such as endoglucanase that act and degrade cellulose, and xylanases that act and degrade hemicellulose. Of these, cellulase is preferably used. In addition, using cellulase and xylanase in combination is one of the preferred forms.

The reaction conditions for the enzyme treatment may be set as appropriate so that the enzyme treatment reaction proceeds sufficiently according to the type and characteristics of the enzyme. The reaction temperature is generally preferably in the range of 20 to 95 ° C., but the preferred reaction temperature varies depending on the type of enzyme. For example, when cellulase is used as the enzyme, the reaction temperature should be in the range of 40 to 55 ° C. Is preferred. The reaction time is preferably 30 minutes or longer, more preferably 1 hour or longer, and further preferably 1.5 hours or longer, from the viewpoint of the balance between the progress of the enzyme treatment reaction and the productivity. On the other hand, it is preferably 24 hours or shorter, more preferably 12 hours or shorter, still more preferably 5 hours or shorter.

In the enzyme treatment reaction, the reaction can be stopped and the reaction can be completed by inactivating the enzyme by a usual method such as changing the pH with hydrochloric acid or the like, or changing the temperature.

In addition, as the enzyme treatment reaction, in addition to the usual method of enzyme treatment such as allowing the enzyme to act on the raw material while appropriately shaking the solution containing the raw material of the cellulose microfibril and the enzyme, the cellulose It can also be carried out by shaking a solution containing a microfibril raw material and a microorganism encapsulating the enzyme, and allowing the enzyme to act on the raw material. The microorganism is not particularly limited as long as it has an enzyme that acts on the raw material of cellulose microfibril and can be decomposed, defibrated, and the like.

When the microfibrillated plant fiber is produced by a method of treating the above-mentioned cellulose microfibril raw material with an enzyme, it is preferable to perform mechanical treatment before or after (preferably after) the enzyme treatment reaction. Thereby, the degree of fiber fibrillation can be further increased, and microfibrillated plant fibers having a small predetermined average fiber diameter can be obtained.

The mechanical treatment method is not particularly limited. For example, microfibrillated plant fiber produced by a method of treating the cellulose microfibril raw material with an enzyme (when mechanical treatment is performed before the enzyme treatment reaction). The above cellulose microfibril raw material) is chemically treated with an alkali such as sodium hydroxide as necessary, and then a refiner, a twin screw kneader (double screw extruder), a twin screw kneading extruder, a high pressure homogenizer, a medium stirring mill And a method of mechanically grinding or beating using a stone mortar, grinder, vibration mill, sand grinder or the like. In addition, as other methods, a method of performing ultra-high pressure treatment and the like can also be mentioned.

In addition, as the microfibrillated plant fiber, those obtained by the above production method, further subjected to oxidation treatment and various chemical modification treatments, and natural products that can be used as raw materials for the cellulose microfibril (for example, Resource biomass such as fruits, cereals, root vegetables, wood, bamboo, hemp, jute, kenaf, and pulp and paper, cloth, agricultural waste, and waste biomass such as food waste and sewage sludge obtained from these, rice straw In addition to unused biomass such as straw, thinned wood, cellulose produced by sea squirts, acetic acid bacteria, etc.), the raw material is subjected to oxidation treatment and various chemical denaturation treatments, and then the enzyme treatment (and further Machined) can also be used, for example, hydrogen atoms of some hydroxyl groups in cellulose microfibrils are cyclic carboxylic acids It is also one of preferred embodiments of the second aspect of the present invention using microfibrillated plant fibers having a structure substituted by a carboxyl group-containing group of the anhydride.

As the microfibrillated plant fiber, from the viewpoint of dispersibility of the microfibrillated plant fiber in rubber, hydrogen atoms of some hydroxyl groups in the cellulose microfibril are substituted with a carboxyl group-containing group of a cyclic carboxylic acid anhydride. What has the structure made can also be used conveniently.

In the present specification, the structure in which some of the hydroxyl atoms in the cellulose microfibril are substituted with the carboxyl group-containing group of the cyclic carboxylic acid anhydride means that the cellulose microfibril reacts with the cyclic carboxylic acid anhydride. And the structure where the hydrogen atom of the one part hydroxyl group in a cellulose microfibril was substituted by the substituent derived from cyclic carboxylic acid anhydride is represented.

Further, as the microfibrillated plant fiber, one having a structure in which hydrogen atoms of some hydroxyl groups in cellulose microfibrils are substituted by carboxyl group-containing groups of cyclic carboxylic acid anhydrides can be used. The plant fiber may have other substituents as long as hydrogen atoms of at least some of the hydroxyl groups in the cellulose microfibrils are substituted with the carboxyl group-containing group of the cyclic carboxylic acid anhydride, What has the structure where the hydrogen atom of all the hydroxyl groups in a cellulose microfibril was substituted by the carboxyl group-containing group of cyclic carboxylic acid anhydride is also contained.

The cyclic carboxylic acid anhydride will be described in detail later.

Examples of the carboxyl group-containing group of the cyclic carboxylic acid anhydride include the following formula (1);

(In the above formula (1), R ¹ represents a linear hydrocarbon group having 1 to 5 carbon atoms which may have a substituent. * Represents a bond.) Groups are mentioned as preferred forms.

In the above formula (1), R ¹ represents a linear hydrocarbon group having 1 to 5 carbon atoms (preferably 1 to 3, more preferably 1 to 2) which may have a substituent. Specific examples of the hydrocarbon group include an alkylene group such as a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and an n-pentylene group; an alkenylene group such as a vinylene group and a propenylene group; It is done.

Among them, as the R ^1, a methylene group, an ethylene group, n- propylene, or a vinylene group is preferably ethylene group or a vinylene group is more preferable.

The substituent that R ¹ may have is a linear or branched chain having 1 to 30 carbon atoms (preferably 1 to 25, more preferably 1 to 20, more preferably 10 to 20, particularly Preferably, hydrocarbon groups of 15 to 20) are mentioned. Specific examples of the hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s- Alkyl groups such as butyl, t-butyl, pentyl, hexyl; alkenyl such as vinyl, propenyl, butenyl, pentenyl, hexenyl, octenyl, decenyl, dodecenyl, hexadecenyl, octadecenyl Group; and the like.

Among them, the substituent that R ¹ may have is preferably a methyl group, an ethyl group, an n-propyl group, a vinyl group, a propenyl group, a dodecenyl group, a hexadecenyl group, or an octadecenyl group, a methyl group, A vinyl group, a hexadecenyl group, or an octadecenyl group is more preferable, and a hexadecenyl group or an octadecenyl group is still more preferable.

The above R ¹ may have the above substituent among the replaceable hydrogen atoms possessed by R ¹ above, to one of which may be substituted by the substituents, two or more of substituted by the above substituent When two or more are substituted, each substituent may be the same or different.

The microfibrillated plant fiber having a structure in which part of the hydroxyl groups in the cellulose microfibril is substituted with a carboxyl group-containing group of a cyclic carboxylic acid anhydride is obtained by the above production method. Can be modified with a cyclic carboxylic acid anhydride (modifying agent), or a natural product that can be used as a raw material for the cellulose microfibrils (for example, resource biomass such as fruits, grains, root vegetables, wood, bamboo, hemp, jute, kenaf, and Produced pulp, paper, cloth, waste from agricultural products, waste biomass such as food waste and sewage sludge, unused biomass such as rice straw, straw and thinned wood, as well as sea squirts and acetic acid bacteria Cellulose etc.) is used as a raw material for cellulose and modified with a cyclic carboxylic acid anhydride (modifying agent). After the enzyme treatment is obtained by and go (even a mechanical process).

Specific examples of the cyclic carboxylic acid anhydride (modifying agent) include cyclic C 4-10 (preferably 4-6) such as succinic anhydride, maleic anhydride, citraconic anhydride, itaconic anhydride. And a compound in which a substituent corresponding to the substituent which R ¹ in the above formula (1) may have is bonded to the cyclic carboxylic anhydride. Among these, from the viewpoint of dispersibility of microfibrillated plant fibers in rubber, succinic anhydride, maleic anhydride, hexadecenyl succinic anhydride, hexadecenyl maleic anhydride, octadecenyl Succinic anhydride and octadecenylmaleic anhydride are preferably used. More preferably hexadecenyl succinic anhydride, hexadecenyl maleic anhydride, octadecenyl succinic anhydride, octadecenyl maleic anhydride, more preferably hexadecenyl succinic anhydride , Octadecenyl succinic anhydride.
These modifiers may be used alone or in combination of two or more.

By reacting the modifying agent with the microfibrillated plant fiber or the cellulose raw material for esterification (denaturation reaction), some hydroxyl groups of cellulose constituting the microfibrillated plant fiber or the cellulose raw material. Are substituted with a substituent (carboxyl group-containing group) derived from a modifying agent (cyclic carboxylic acid anhydride).

In addition, water contained in the microfibrillated plant fiber or the cellulose raw material in advance, such as toluene or N-methylpyrrolidone, is prevented so that the reaction between the denaturing agent and the microfibrillated plant fiber or the cellulose raw material is not inhibited. It is preferable to substitute with a solvent.

A method for performing the esterification reaction between the modifying agent and the microfibrillated plant fiber or the cellulose raw material is not particularly limited, and a method that is usually performed as a method for performing the esterification reaction may be employed. For example, it can be performed by any of the following methods. The microfibrillated plant fiber having a structure in which hydrogen atoms of some hydroxyl groups in the obtained cellulose microfibril are substituted with the carboxyl group-containing group of the cyclic carboxylic acid anhydride is usually washed with water, filtered, and dried. It can be used as a microfibrillated plant fiber to be removed and mixed with the rubber composition for tires by removing the solvent and the catalyst.
(I) An esterification catalyst such as a modifier (cyclic carboxylic acid anhydride) and, if necessary, potassium carbonate, is dispersed in a dispersion liquid in which the microfibrillated plant fiber or the cellulose raw material previously substituted with a solvent is dispersed. Add sequentially or in batches to react.
(II) A modifying agent (cyclic carboxylic acid anhydride), the microfibrillated plant fiber or the cellulose raw material, and, if necessary, an esterification catalyst such as potassium carbonate are mixed and reacted.

The addition ratio of the modifying agent to the microfibrillated plant fiber or the cellulose raw material is preferably 5 to 150% by mass from the viewpoint of the balance between the addition efficiency and the dispersibility of the microfibrillated plant fiber in rubber. 10 to 100% by mass is more preferable.
In addition, the addition rate with respect to the said microfibrillated plant fiber or the said cellulose raw material of the said modifier | denaturant can be calculated with the calculation method performed in the Example mentioned later.

<Other ingredients>
In the rubber composition of the second invention, in addition to the components described above, other compounding agents conventionally used in the rubber industry, such as reinforcing agents (carbon black, silica, etc.), silane coupling agents, vulcanizing agents. , Stearic acid, vulcanization accelerator, vulcanization acceleration aid, oil, curing resin, wax, anti-aging agent and the like.

<Method for producing rubber composition>
The rubber composition of the second present invention is a rubber component, the microfibrillated plant fiber, and other necessary compounding agents, for example, mixed by a conventionally known method using a rubber kneader or the like, A method for producing a rubber composition, which can be produced by vulcanization by a conventionally known method and includes a step of mixing a rubber component and the microfibrillated plant fiber, is also one of the second aspects of the present invention. However, for example, it is preferable that the microfibrillated plant fiber and the rubber component are mixed in advance and then mixed with other necessary compounding agents. In addition, after mixing the said microfibrillated plant fiber and a rubber component previously, when mixing other required compounding agents, you may mix a rubber component further.

That is, the method for producing a rubber composition including the step (i) of previously mixing the microfibrillated plant fiber and the rubber component is also one of the second aspects of the present invention.

In the step (i), the microfibrillated plant fiber and a rubber component are mixed. Thus, the microfibrillated plant fiber can be more uniformly dispersed in the rubber composition by previously mixing the microfibrillated plant fiber and the rubber component. In the step, the microfibrillated plant fiber and the rubber component are preferably mixed in a solvent such as water from the viewpoint that the microfibrillated plant fiber and the rubber component can be easily mixed. In addition, it does not specifically limit as the said mixing method, For example, common methods, such as a propeller-type stirring apparatus, a homogenizer, a rotary stirring apparatus, an electromagnetic stirring apparatus, manual stirring, can be used.

In the step (i), it is preferable to use a solvent dispersion (particularly preferably an aqueous dispersion) of the microfibrillated plant fiber. Thereby, the said microfibrillated plant fiber and a rubber component can be mixed uniformly in a short time. In the microfibrillated plant fiber dispersion (100% by mass), the content (solid content) of the microfibrillated plant fiber is preferably 2 to 40% by mass, more preferably 5 to 30% by mass.

The dispersion of the microfibrillated plant fiber can be produced by a known method, and the production method is not particularly limited. For example, the microfibrillated plant fiber is obtained using a high-pressure homogenizer, an ultrasonic homogenizer, a colloid mill, or the like. It can be prepared by dispersing in a solvent such as water.

Moreover, in the said process (i), it is preferable to use rubber latex as a rubber component. Thereby, the said microfibrillated plant fiber and a rubber component can be mixed more uniformly in a short time.

Examples of the rubber latex include latexes of the rubber components described above. Specific examples include natural rubber latex, synthetic diene rubber latex (butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene). Diene rubber latex such as butadiene rubber (SIBR), isoprene rubber, acrylonitrile butadiene rubber, ethylene vinyl acetate rubber, chloroprene rubber, vinyl pyridine rubber, butyl rubber and the like) can be suitably used. Thus, the rubber latex is a diene rubber latex, which is one of the preferred embodiments of the second invention. These rubber latexes may be used alone or in combination of two or more. Among these, natural rubber latex, SBR latex, BR latex, and isoprene rubber latex are more preferable, and natural rubber latex is particularly preferable because the effect of the second aspect of the present invention can be more suitably obtained.

Natural rubber latex is collected as the sap of natural rubber trees such as Hevea, and contains rubber, water, proteins, lipids, inorganic salts, etc., and the gel content in rubber is based on the complex presence of various impurities. It is considered a thing. In the second aspect of the present invention, as a natural rubber latex, raw latex (field latex) produced by tapping Hevea tree, concentrated latex concentrated by centrifugation or creaming method (purified latex, ammonia added by a conventional method) High ammonia latex, zinc oxide, TMTD, LATZ latex stabilized by ammonia, etc.) can be used.

The pH of the rubber latex is preferably 8.5 or higher, more preferably 9.5 or higher. Moreover, Preferably it is 12 or less, More preferably, it is 11 or less. By setting the pH of the rubber latex in such a range, deterioration of the rubber latex can be suppressed and kept in a stable state.

The rubber latex can be prepared by a conventionally known production method, and various commercially available products can also be used. In addition, it is preferable to use a rubber latex having a rubber solid content of 30 to 80% by mass. More preferably, it is 40-70 mass%.

In the said process (i), it is preferable to mix | blend each component so that it may become the above-mentioned content in the rubber composition of 2nd this invention. Thereby, the effect of the second aspect of the present invention can be sufficiently obtained. In addition, the yield and workability of various materials are improved.

Through the step (i), a master batch in which the microfibrillated plant fibers are uniformly dispersed in a rubber matrix can be prepared. In addition, when the mixture obtained by the said process (i) is a slurry state, after solidifying and drying the said mixture by a well-known method, a masterbatch can be prepared by knead | mixing with a Banbury mixer etc. In addition, when rubber latex is used as the rubber component in the step (i), a mixture of the rubber latex and the microfibrillated plant fiber is stirred with a homogenizer or the like to obtain a dispersion, and then coagulated and dried by a known method. By doing so, a master batch can be prepared. The rubber composition in the second aspect of the present invention can be obtained by kneading this master batch with other compounding agents.
In addition, this masterbatch may contain components other than a rubber component and the said microfibrillated plant fiber in the range which does not inhibit the effect of 2nd this invention.

The rubber composition of the second present invention can be used for a tire member. Thus, the tire produced using the tire rubber composition of the second invention is also one of the second inventions. Examples of the tire include a pneumatic tire, a studless tire (winter tire), a run flat tire, and the like.

The tire of the second aspect of the present invention is manufactured by a usual method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of each member of the tire at an unvulcanized stage and molded by a normal method on a tire molding machine. After forming an unvulcanized tire by heating, the tire can be manufactured by heating and pressing in a vulcanizer.

When the tire of the second invention is a pneumatic tire, the members to which the rubber composition of the second invention can be applied include sidewalls, base treads, bead apex, clinch apex, inner liner, under tread. , Breaker topping, pretopping, tread and the like, and among them, it can be suitably used for tread and sidewall.

When the tire of the second aspect of the present invention is a pneumatic tire, it can be suitably used for passenger cars, trucks, buses and the like.

Next, the case where the tire of the second aspect of the present invention is a studless tire will be described.

The rubber composition of the second present invention contains a rubber component and microfibrillated plant fibers having an average fiber diameter of 1 nm or more and less than 20 nm. As the microfibrillated plant fiber to be blended in the rubber composition, an average fiber diameter of 1 nm or more and less than 20 nm and a fiber having a high degree of fibrillation and a small average fiber diameter are used so that the microfibrillated plant fiber is aggregated in rubber. And the dispersibility of the microfibrillated plant fiber in the rubber is further increased. Therefore, the dispersibility of the microfibrillated plant fiber in the rubber can be further improved by blending the microfibrillated plant fiber having an average fiber diameter of 1 nm or more and less than 20 nm into the rubber composition. And the reinforcement property can be improved. Therefore, when the rubber composition of the second aspect of the present invention is applied to each member of the studless tire, the studless tire improved in wet grip performance, on-ice performance, wear resistance, and reinforcement while maintaining low fuel consumption. Can provide.

When the rubber composition of the second aspect of the present invention is applied to each member of a studless tire, the same rubber component as described above can be used as the rubber component. It is preferable that natural rubber (NR) and butadiene rubber (BR) are included from the viewpoint of imparting performance.

The content of natural rubber in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 40% by mass or more. Further, the content is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less, and particularly preferably 60% by mass or less. When the content of the natural rubber is within such a range, the performance on ice and the wear resistance can be further improved while maintaining low fuel consumption.

The content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 40% by mass or more from the viewpoint of exerting necessary on-ice performance. In addition, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 60% by mass or less, from the viewpoint of workability.

When the rubber composition of the second aspect of the present invention is applied to each member of a studless tire, examples of the microfibrillated plant fiber used include those described above.

When the rubber composition of the second invention is applied to each member of a studless tire, the content of the microfibrillated plant fiber is preferably 1 part by mass or more, more preferably 100 parts by mass of the rubber component. It is 3 parts by mass or more, more preferably 5 parts by mass or more, preferably 100 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the above-mentioned microfibrillated plant fibers can be well dispersed and the performance on ice and wet grip performance can be further improved while maintaining low fuel consumption.

When the rubber composition of the second invention is applied to each member of a studless tire, the rubber composition of the second invention preferably contains oil as a plasticizer. Thereby, the hardness can be adjusted to an appropriate low level and good on-ice performance can be obtained. Although it does not specifically limit as oil, For example, process oil, vegetable oil, or its mixture can be used. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Of these, paraffinic process oil is preferably used.

The oil content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and still more preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component. The content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is in the said range, performance on ice can be improved more.

The rubber composition of the second present invention includes cap tread, base tread, under tread, clinch apex, bead apex, sidewall, breaker, edge band, full band, breaker cushion rubber, carcass cord covering rubber, etc. It can be used for each member of a studless tire, and can be particularly suitably used for a tread.

The studless tire which has the member produced using the rubber composition of the 2nd present invention is manufactured by the usual method using the above-mentioned rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of each member (tread, etc.) at an unvulcanized stage and molded on a tire molding machine by a normal method. And it bonds together with another tire member, and forms an unvulcanized tire. The unvulcanized tire can be heated and pressurized in a vulcanizer to produce the studless tire of the second invention.

A studless tire having a member produced using the rubber composition of the second invention can be suitably used for passenger cars, trucks and buses (heavy duty vehicles), and the like.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Various chemicals used in the following examples, comparative examples and reference examples will be described together.
Natural rubber latex: HYTEX HA (natural rubber latex manufactured by Golden Hope Plantations, solid content: 60% by mass, average particle size: 1 μm)
Microfibrillated plant fiber: Selish KY-100G manufactured by Daicel Chemical Industries, Ltd. (average fiber length: 0.5 mm, average fiber diameter: 0.02 μm, solid content: 10% by mass)
Lecithin: SLP-White (manufactured by Sakai Oil Co., Ltd.) (High-purity lecithin derived from soybean, phospholipid (acetone insoluble) content: 96 to 98% by mass)
Saponin: Saponin master batch 1-1 to 1-10 manufactured by Yoneyama Pharmaceutical Co., Ltd .: prepared in the following production examples BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.
Oil: Mineral oil PW-380 (paraffinic process oil) manufactured by Idemitsu Kosan Co., Ltd.
Carbon black: N220 manufactured by Cabot Japan
Anti-aging agent: Nocrack 6C (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Beads manufactured by NOF Corporation Zinc stearate zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical NOCELLER DM (di-2-benzothiazolyl disulfide) manufactured by Kogyo Co., Ltd.

<Production Examples 1-1 to 1-3: Preparation of master batches 1-1 to 1-3>
In accordance with the formulation shown in Table 1-1, the microfibrillated plant fiber and lecithin were stirred in water at 24,000 rpm for 1 hour using a high-speed homogenizer (IKA's batch homogenizer T65D Ultra Turrax (Ultraturrax T25)). Then, natural rubber latex was added, and the mixture was further stirred and dispersed for 30 minutes. The obtained mixture was coagulated with a 5 mass% formic acid aqueous solution, washed with water, and dried in a heating oven at 40 ° C to obtain master batches 1-1 to 1-3.

<Production Examples 1-4 to 1-6: Preparation of master batches 1-4 to 1-6>
According to the formulation shown in Table 1-1, the microfibrillated plant fiber and saponin were stirred for 1 hour in water at 24,000 rpm using a high-speed homogenizer (IKA's batch homogenizer T65D Ultra Turrax (Ultraturrax T25)). Then, natural rubber latex was added, and the mixture was further stirred and dispersed for 30 minutes. The obtained mixed solution was solidified with a 5% by mass aqueous formic acid solution, washed with water, and then dried in a heating oven at 40 ° C. to obtain master batches 1-4 to 1-6.

<Production Example 1-7: Preparation of master batch 1-7>
Master batch 1-7 was obtained in the same manner as master batch 1-1 except that lecithin was not blended.

<Production Example 1-8: Preparation of master batch 1-8>
The natural rubber latex was coagulated as it was with a 5% by mass aqueous formic acid solution, washed with water, and then dried in a heating oven at 40 ° C. to obtain a master batch 1-8.

<Production Example 1-9: Preparation of masterbatch 1-9>
Master batch 1-9 was obtained in the same manner as master batch 1-2, except that the microfibrillated plant fiber was not blended.

<Production Example 1-10: Preparation of master batch 1-10>
Master batch 1-10 was obtained in the same manner as master batch 1-5 except that the microfibrillated plant fiber was not blended.

<Preparation of vulcanized rubber composition>
According to the formulation of Table 1-2 and 1-3, using a 250 cc internal mixer ripened to 135 ° C., the vulcanization accelerator and chemicals other than sulfur and various master batches were kneaded for 3 minutes under the condition of 88 rpm. Thereafter, the kneaded rubber was discharged, the vulcanization accelerator and sulfur were added with a 6-inch open roll at 60 ° C. and 24 rpm, and kneaded for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-heated at 150 ° C. to obtain a vulcanized rubber composition.

<Examples, comparative examples and reference examples>
The following evaluation was performed using the vulcanized rubber composition produced by the above method. In addition, about each index | exponent in the characteristic data shown to Table 1-2 and 1-3, Reference Example 1-1 was made into the reference | standard mixing | blending, and it computed with the following formula. In Table 1-2, the content of non-petroleum resources is the content (mass%) of non-petroleum resources in 100% by mass of the rubber composition.

(Tensile test)
A tensile test was conducted using No. 3 dumbbell according to JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”. 100% tensile stress, 300% tensile stress, tensile strength, elongation at break, fracture energy Was measured. The following formula:
100% tensile stress index = (100% tensile stress of each formulation) / (100% tensile stress of standard formulation) × 100
300% tensile stress index = (300% tensile stress of each formulation) / (300% tensile stress of standard formulation) × 100
Tensile strength index = (breaking stress of each compound) / (breaking stress of the standard compound) × 100
Breaking elongation index = (breaking elongation of each formulation) / (breaking elongation of the reference formulation) × 100
Fracture energy index = (Fracture energy of each formulation) / (Fracture energy of the reference formulation) × 100
Were used to calculate a 100% tensile stress index, a 300% tensile stress index, a tensile strength index, a breaking elongation index, and a breaking energy index. The larger the index, the better the vulcanized rubber composition is reinforced, and the higher the mechanical strength of the rubber, the better the fracture characteristics.

(Maneuvering stability index and rolling resistance index)
A test specimen for measurement was cut out from a 2 mm rubber slab sheet of the vulcanized rubber composition prepared by the above-described method, and the temperature was 70 ° C. and the initial strain was 10% using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho). The E * (complex elastic modulus) and tan δ (loss tangent) of each test specimen were measured under the conditions of dynamic strain 2% and frequency 10 Hz. The following formula:
Steering stability index = (E * for each formulation) / (E * for standard formulation) × 100
Rolling resistance index = (tan δ of each formulation) / (tan δ of reference formulation) × 100
The steering stability index and rolling resistance index were calculated. The larger the steering stability index, the better the steering stability when used as a pneumatic tire, and the smaller the rolling resistance index, the better the rolling resistance characteristic (low fuel consumption) when used as a pneumatic tire. Indicates to give.

From Table 1-2, in Examples containing rubber components, microfibrillated plant fibers, and emulsifiers, while maintaining good fuel economy, the elongation at break is maintained or improved, tensile stress, tensile strength, fracture energy, Steering stability has been significantly improved, and the performance balance of fracture characteristics, steering stability and fuel efficiency has been significantly improved.
Furthermore, from Table 1-3, when containing microfibrillated plant fiber and not containing an emulsifier (Comparative Example 1-1), and containing lecithin and not containing microfibrillated plant fiber (Comparative Example 1). -2), when microfibrillated plant fiber and lecithin are contained (Example 1-2), the tensile stress, the tensile strength, the elongation at break, the fracture energy, the handling stability, and the rolling resistance are synergistic. The balance of performance between fracture characteristics, handling stability, and fuel efficiency can be remarkably and synergistically improved.
Similarly, in the case of containing microfibrillated plant fibers and not containing an emulsifier (Comparative Example 1-1) and in the case of containing saponin and not containing microfibrillated plant fibers (Comparative Example 1-3). In comparison, when microfibrillated plant fiber and saponin are contained (Example 1-5), the tensile stress, tensile strength, elongation at break, fracture energy, handling stability, and rolling resistance are remarkably improved synergistically. It was possible to remarkably and synergistically improve the performance balance of destructive characteristics, handling stability and fuel efficiency.

<Preparation of vulcanized rubber composition>
According to the composition of Table 1-4, using a 250 cc internal mixer ripened to 135 ° C, the vulcanization accelerator and chemicals other than sulfur and various master batches were kneaded for 3 minutes under the condition of 88 rpm, and then kneaded. The vulcanized accelerator and sulfur were added with a 6-inch open roll under the conditions of 60 ° C. and 24 rpm, and kneaded for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-heated at 150 ° C. to obtain a vulcanized rubber composition.

<Examples, comparative examples and reference examples>
The following evaluation was performed using the vulcanized rubber composition produced by the above method. In addition, about each index in the characteristic data shown in Table 1-4, Reference Example 1-11 was used as a standard composition, and the calculation formula described below was used.

(Maneuvering stability index and rolling resistance index)
A test specimen for measurement was cut out from a 2 mm rubber slab sheet of the vulcanized rubber composition prepared by the above-described method, and the temperature was 70 ° C. and the initial strain was 10% using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho). The E * (complex elastic modulus) and tan δ (loss tangent) of each test specimen were measured under the conditions of dynamic strain 2% and frequency 10 Hz. The following formula:
Steering stability index = (E * for each formulation) / (E * for standard formulation) × 100
Rolling resistance index = (tan δ of each formulation) / (tan δ of reference formulation) × 100
The steering stability index and rolling resistance index were calculated. The higher the steering stability index, the better the steering stability when used as a studless tire, and the smaller the rolling resistance index, the better the rolling resistance characteristics (low fuel consumption) when used as a studless tire. Indicates.

(Performance on ice)
Friction coefficient (friction on ice) when the vulcanized rubber test piece was pressed at 2 kg / cm ² and slid at 20 km / hour on an ice surface of −2 ° C. installed in a temperature controlled room at −5 ° C. The coefficient of friction on ice of Reference Example 1-11 was set to 100, and the coefficient of friction on ice of each formulation was displayed as an index according to the following formula. The larger the on-ice friction performance index, the higher the on-ice friction performance, and the better the on-ice performance when used as a studless tire.
(Friction index on ice) = (Friction coefficient on ice for each formulation) / (Friction coefficient on ice in Reference Example 1-11) × 100

From Table 1-4, in the Example containing a rubber component, microfibrillated plant fiber, and an emulsifier, the performance balance of on-ice performance, handling stability, and fuel efficiency is remarkably improved as compared with Reference Example 1-11. did it. Furthermore, it contains a microfibrillated plant fiber and does not contain an emulsifier (Comparative Example 1-11), and contains lecithin and does not contain a microfibrillated plant fiber (Comparative Example 1-12). In the case of containing the microfibrillated plant fiber and lecithin (Example 1-12), the on-ice performance, the handling stability and the rolling resistance can be synergistically improved, and the on-ice performance, the handling stability and the low fuel consumption can be improved. The performance balance could be improved synergistically. Similarly, in the case of containing microfibrillated plant fibers and not containing an emulsifier (Comparative Example 1-11) and in the case of containing saponin and not containing microfibrillated plant fibers (Comparative Example 1-13). In comparison, when containing microfibrillated plant fiber and saponin (Example 1-14), performance on ice, steering stability, and rolling resistance can be synergistically improved, and performance on ice, steering stability and low fuel consumption The performance balance of sex could be improved synergistically.

<Preparation Example 2-1: Preparation of microfibrillated plant fiber 2-1>
Cellulase (Cellic Ctec2, Novozyme), 0.5 mL in a container with a capacity of 2000 mL containing 250.00 g (solid content: 50.00 g) of softwood bleached kraft pulp containing water (NBKP, manufactured by Nippon Paper Industries Co., Ltd.) ) Was added, and the reaction was carried out at 50 ° C. and a shaking speed of 100 rpm for 3 hours.
The solution after completion of the enzyme reaction was prepared to a solid content concentration of 2.0% by mass, and then hydrochloric acid was added so that the hydrochloric acid concentration in the batch was 0.6%, followed by stirring at 75 ° C. for 3 hours. The obtained mixture was repeatedly washed with water until the pH reached approximately 7.0, and then dehydrated so that the solid concentration was 30% by mass. Next, microfibrillated plant fiber 2-1 was prepared by treating the obtained hydrous pulp with a twin-screw kneading extruder at 400 rpm and 0 ° C. operating conditions. When the average fiber diameter and the average fiber length were calculated by the following methods, the average fiber diameter was 4.7 nm and the average fiber length was 83.5 μm.

(Calculation of average fiber diameter and average fiber length)
A 0.001 mass% aqueous dispersion of microfibrillated plant fiber 2-1 was prepared. This diluted dispersion was thinly spread on a mica sample stage and dried by heating at 50 ° C. to prepare an observation sample. By observing the sample with an atomic force microscope (AFM, manufactured by Hitachi High-Tech Science Co., Ltd., product name “Scanning Probe Microscope SPI3800N”) and measuring the cross-sectional height of the shape image, the average fiber diameter and average fiber length Was calculated.

<Production Examples 2-1 to 2-2: Preparation of master batches 2-1 to 2-2>
In accordance with the formulation shown in Table 2-1, the microfibrillated plant fiber 2-1 was submerged in water for 1 hour at 24,000 rpm using a high-speed homogenizer (IKA's batch homogenizer T65D Ultra Tarrax (Ultraturrax T25)). After stirring and dispersing, natural rubber latex (HYTEX HA (natural rubber latex manufactured by Golden Hope Plantations), solid content: 60% by mass, average particle size: 1 μm) is added, and further 30 The mixture was stirred and dispersed for a minute. The obtained mixture was coagulated with a 5 mass% formic acid aqueous solution, washed with water, and dried in a heating oven at 40 ° C to obtain master batches 2-1 to 2-2.

<Production Example 2-3: Preparation of masterbatch 2-3>
The natural rubber latex was coagulated with a 5 mass% formic acid aqueous solution as it was, washed with water, and then dried in a heating oven at 40 ° C to obtain a master batch 2-3.

<Examples 2-1 to 2-2, Comparative Example 2-1>
Hereinafter, various chemicals used in Examples 2-1 to 2-2 and Comparative Example 2-1 will be described together.
Master batches 2-1 to 2-3: prepared in the above Production Examples 2-1 to 2-3 Anti-aging agent: NOCRACK 6C (N-phenyl-N ′-(1,3) manufactured by Ouchi Shinsei Chemical Co., Ltd. -Dimethylbutyl) -p-phenylenediamine)
Stearic acid: Beads manufactured by NOF Corporation Zinc stearate zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical NOCELLER DM (di-2-benzothiazolyl disulfide) manufactured by Kogyo Co., Ltd.

<Preparation of vulcanized rubber composition>
According to the composition of Table 2-2, using a 250 cc internal mixer ripened to 135 ° C., the vulcanization accelerator and chemicals other than sulfur and various master batches were kneaded for 3 minutes under the condition of 88 rpm, and then kneaded. The vulcanized accelerator and sulfur were added with a 6-inch open roll under the conditions of 60 ° C. and 24 rpm, and kneaded for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-heated at 150 ° C. to obtain a vulcanized rubber composition.

<Evaluation>
The following evaluation was performed using the vulcanized rubber composition produced by the above method. The results are shown in Table 2-2.

(Tensile test)
In accordance with JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, a tensile test was conducted using a No. 3 dumbbell-shaped test piece made of a vulcanized rubber composition, and the vulcanized rubber composition was broken. The elongation at break (tensile elongation; EB [%]) and the tensile strength at break (tensile break strength; TB [MPa]) were measured. From the obtained value, the breaking strength was obtained by the following formula, and displayed as an index when the comparative example 2-1 was set to 100 (breaking strength index). The larger the index, the better the fracture strength.
Breaking strength = EB x TB / 2

(Abrasion test)
The amount of wear was measured at room temperature, a load of 1.0 kgf, and a slip rate of 30% using a Lambourne wear tester. The reciprocal of the obtained amount of wear was expressed as an index when the comparative example 2-1 was set to 100 (wear resistance index). It shows that it is excellent in abrasion resistance, so that an index | exponent is large.

From Table 2-2, in an example including a rubber component and microfibrillated plant fiber having an average fiber diameter of 1 nm or more and less than 20 nm, wear resistance and breaking strength (reinforcing property) could be remarkably improved. .

<Preparation Example 2-11: Preparation of microfibrillated plant fiber 2-11>
Cellulase (Cellic Ctec2, Novozyme), 0.5 mL in a container with a capacity of 2000 mL containing 250.00 g (solid content: 50.00 g) of softwood bleached kraft pulp containing water (NBKP, manufactured by Nippon Paper Industries Co., Ltd.) ) Was added, and the reaction was carried out at 50 ° C. and a shaking speed of 100 rpm for 3 hours.
The solution after completion of the enzyme reaction was prepared to a solid content concentration of 2.0% by mass, and then hydrochloric acid was added so that the hydrochloric acid concentration in the batch was 0.6%, followed by stirring at 75 ° C. for 3 hours. The obtained mixture was repeatedly washed with water until the pH reached approximately 7.0, and then dehydrated so that the solid concentration was 30% by mass. Subsequently, the hydrous pulp obtained was processed with a twin-screw kneader / extruder under operating conditions of 400 rpm and 0 ° C. to prepare unmodified microfibrillated plant fibers.

200.00 g of the obtained unmodified microfibrillated plant fiber and 200.00 g of N-methylpyrrolidone were charged into a container having a volume of 2000 mL, and water was distilled off to obtain a solvent-substituted fiber. The system was brought to 70 ° C., 39.70 g of hexadecenyl succinic anhydride and 8.50 g of potassium carbonate (esterification catalyst) were added and reacted for 2 hours. The reaction product was washed successively with ethanol, acetic acid, water, solvent-substituted with ethanol, and then dried to give microfibrillated plant fibers 2-11 (hydrogen atoms of some hydroxyl groups in cellulose microfibrils were cyclic carboxylic acid anhydrides) And having a structure substituted with a carboxyl group-containing group). Ethanol was used as a washing solvent for the sample for evaluating the addition rate of hexadecenyl succinic anhydride. It was 60.6 mass% when the addition rate of the hexadecenyl succinic anhydride with respect to an unmodified | denatured microfibrillated plant fiber in the microfibrillated plant fiber 2-11 was measured by the following method. Moreover, when the average fiber diameter and average fiber length of the microfibrillated plant fiber 2-11 were calculated by the following method, the average fiber diameter was 5.1 nm and the average fiber length was 98.7 μm.

(Measurement of addition rate of hexadecenyl succinic anhydride to unmodified microfibrillated plant fiber)
The addition rate was calculated from the mass change before and after modification of the microfibrillated plant fiber as shown in the following formula (I). A sample for evaluating the addition rate was washed with a sufficient amount of solvent and subjected to measurement.
Wp = (W−Ws) × 100 / Ws (I)
Wp: Addition ratio of hexadecenyl succinic anhydride to unmodified microfibrillated plant fiber (mass%)
W: Dry mass (g) of the modified microfibrillated plant fiber (microfibrillated plant fiber 2-11)
Ws: dry mass of unmodified microfibrillated plant fiber before modification (g)

(Calculation of average fiber diameter and average fiber length)
A 0.001 mass% aqueous dispersion of microfibrillated plant fiber 2-11 was prepared. This diluted dispersion was thinly spread on a mica sample stage and dried by heating at 50 ° C. to prepare an observation sample. By observing the sample with an atomic force microscope (AFM, manufactured by Hitachi High-Tech Science Co., Ltd., product name “Scanning Probe Microscope SPI3800N”) and measuring the cross-sectional height of the shape image, the average fiber diameter and average fiber length Was calculated.

<Production Examples 2-11 to 2-12: Preparation of master batches 2-11 to 2-12>
In accordance with the composition shown in Table 2-3, the microfibrillated plant fiber 2-11 was submerged in water at 24,000 rpm for 1 hour using a high-speed homogenizer (IKA's batch homogenizer T65D Ultra Turrax (Ultraturrax T25)). After stirring and dispersing, natural rubber latex (HYTEX HA (natural rubber latex manufactured by Golden Hope Plantations), solid content: 60% by mass, average particle size: 1 μm) is added, and further 30 The mixture was stirred and dispersed for a minute. The obtained mixed solution was coagulated with a 5 mass% formic acid aqueous solution, washed with water, and dried in a heating oven at 40 ° C to obtain master batches 2-11 to 2-12.

<Production Example 2-13: Preparation of master batch 2-13>
The natural rubber latex was coagulated with a 5 mass% formic acid aqueous solution as it was, washed with water, and dried in a heating oven at 40 ° C to obtain a master batch 2-13.

<Examples 2-11 to 2-12, Comparative Example 2-11>
Hereinafter, various chemicals used in Examples 2-11 to 2-12 and Comparative Example 2-11 will be described together.
Master batches 2-11 to 2-13: prepared in the above production examples 2-11 to 2-13 Anti-aging agent: Nocrack 6C (N-phenyl-N ′-(1,3) manufactured by Ouchi Shinsei Chemical Co., Ltd. -Dimethylbutyl) -p-phenylenediamine)
Stearic acid: Beads manufactured by NOF Corporation Zinc stearate zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical NOCELLER DM (di-2-benzothiazolyl disulfide) manufactured by Kogyo Co., Ltd.

<Preparation of vulcanized rubber composition>
According to the composition of Table 2-4, using a 250 cc internal mixer ripened to 135 ° C., the vulcanization accelerator and chemicals other than sulfur and various master batches were kneaded for 3 minutes under the condition of 88 rpm, and then kneaded. The vulcanized accelerator and sulfur were added with a 6-inch open roll under the conditions of 60 ° C. and 24 rpm, and kneaded for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-heated at 150 ° C. to obtain a vulcanized rubber composition.

<Evaluation>
The following evaluation was performed using the vulcanized rubber composition produced by the above method. The results are shown in Table 2-4.

(Tensile test)
In accordance with JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, a tensile test was conducted using a No. 3 dumbbell-shaped test piece made of a vulcanized rubber composition, and the vulcanized rubber composition was broken. The elongation at break (tensile elongation; EB [%]) and the tensile strength at break (tensile break strength; TB [MPa]) were measured. The fracture strength was determined from the obtained value by the following formula, and displayed as an index when Comparative Example 2-11 was set to 100 (destructive strength index). It shows that it is excellent in fracture strength, so that an index | exponent is large.
Breaking strength = EB x TB / 2

(Abrasion test)
The amount of wear was measured at room temperature, a load of 1.0 kgf, and a slip rate of 30% using a Lambone-type wear tester. The reciprocal of the obtained amount of wear was expressed as an index when the comparative example 2-11 was set to 100 (wear resistance index). It shows that it is excellent in abrasion resistance, so that an index | exponent is large.

From Table 2-4, a rubber component and an average fiber diameter of 1 nm or more and less than 20 nm, and a structure in which hydrogen atoms of some hydroxyl groups in cellulose microfibrils are substituted with carboxyl group-containing groups of cyclic carboxylic acid anhydrides In the examples including the microfibrillated plant fiber having, the abrasion resistance and the breaking strength (reinforcing property) could be remarkably improved.

<Examples 2-21 to 2-22, Comparative Example 2-21>
Hereinafter, various chemicals used in Examples 2-21 to 2-22 and Comparative Example 2-21 will be described together.
Master batches 2-1 to 2-3: prepared in the above Production Examples 2-1 to 2-3 BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.
Anti-aging agent: Nocrack 6C (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Beads manufactured by NOF Corporation Zinc stearate zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical NOCELLER DM (di-2-benzothiazolyl disulfide) manufactured by Kogyo Co., Ltd.

<Preparation of vulcanized rubber composition>
According to the composition of Table 2-5, using a 250 cc internal mixer ripened to 135 ° C., the vulcanization accelerator and chemicals other than sulfur and various master batches were kneaded for 3 minutes under the condition of 88 rpm, and then kneaded. The vulcanized accelerator and sulfur were added with a 6-inch open roll under the conditions of 60 ° C. and 24 rpm, and kneaded for 5 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-heated at 150 ° C. to obtain a vulcanized rubber composition.

Further, the obtained unvulcanized rubber composition is molded into a tread shape, and is bonded together with other tire members on a tire molding machine to form an unvulcanized tire and vulcanize to obtain a test tire (size: 195 / 65R15, studless tire for passenger cars).

<Evaluation>
The following evaluation was performed using the vulcanized rubber composition and the test tire produced by the above method. The results are shown in Table 2-5.

(Tensile test)
In accordance with JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, a tensile test was conducted using a No. 3 dumbbell-shaped test piece made of a vulcanized rubber composition, and the vulcanized rubber composition was broken. The elongation at break (tensile elongation; EB [%]) and the tensile strength at break (tensile break strength; TB [MPa]) were measured. From the obtained value, the breaking strength was determined by the following formula, and displayed as an index when the comparative example 2-21 was set to 100 (breaking strength index). The larger the index, the better the fracture strength when used as a studless tire.
Breaking strength = EB x TB / 2

(Abrasion test)
The amount of wear was measured at room temperature, a load of 1.0 kgf, and a slip rate of 30% using a Lambone-type wear tester. The reciprocal of the obtained wear amount was displayed as an index when the comparative example 2-21 was set to 100 (wear resistance index). The larger the index, the better the wear resistance when used as a studless tire.

(Wet grip performance)
Wet grip performance was evaluated using a flat belt friction tester (FR5010 type) manufactured by Ueshima Seisakusho. A cylindrical rubber test piece having a width of 20 mm and a diameter of 100 mm made of the above vulcanized rubber composition was used as a sample, and the slip ratio of the sample with respect to the road surface was set to 0 to 20 km / hour, a load of 4 kgf, and a road surface temperature of 20 ° C. It was changed to 70%, and the maximum value of the friction coefficient detected at that time was read. With Comparative Example 2-21 as 100, the measurement results were displayed as an index according to the following formula. The larger the index, the better the wet grip performance when used as a studless tire.
(Wet grip performance index) = (maximum friction coefficient of each formulation) / (maximum friction coefficient of Comparative Example 2-21) × 100

(Performance on ice [Grip performance on ice])
Using the test tire, the actual vehicle performance was evaluated on ice under the following conditions. The test tire was mounted on a domestic 2000cc FR vehicle. The test place was the Hokkaido Asahikawa test course (on ice) of Sumitomo Rubber Industries, Ltd., and the on-ice temperature was -1 to -6 ° C.
Braking performance (on-ice braking stop distance): The stop distance on ice required to depress and stop the lock brake at a speed of 30 km / h was measured. With Comparative Example 2-21 as 100, the measurement results were displayed as an index according to the following formula. The larger the index, the better the braking performance on ice (ice performance) when used as a studless tire.
(Performance index on ice) = (Stop distance of Comparative Example 2-21) / (Stop distance of each formulation) × 100

(Viscoelasticity test)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was measured under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of 2%. It was measured. With Comparative Example 2-21 as 100, the measurement results were displayed as an index according to the following formula. The larger the index, the better the rolling resistance and the lower the heat buildup (low fuel consumption) when used as a studless tire.
(Rolling resistance index) = (tan δ of Comparative Example 2-21) / (tan δ of each formulation) × 100

From Table 2-5, in Examples including a rubber component and microfibrillated plant fiber having an average fiber diameter of 1 nm or more and less than 20 nm, wet grip performance, on-ice performance, and abrasion resistance are maintained while maintaining low fuel consumption. And, the breaking strength (reinforcing property) could be remarkably improved.

Claims (15)

A tire rubber composition comprising a rubber component, microfibrillated plant fibers, and an emulsifier. The tire rubber composition according to claim 1, wherein the rubber component includes at least one selected from the group consisting of natural rubber, modified natural rubber, synthetic rubber, and modified synthetic rubber. The rubber composition for a tire according to claim 1 or 2, wherein the microfibrillated plant fiber is cellulose microfibril. The rubber composition for a tire according to any one of claims 1 to 3, wherein the microfibrillated plant fiber has an average fiber diameter of 1 to 100 nm. The rubber composition for a tire according to any one of claims 1 to 4, wherein a content of the microfibrillated plant fiber is 1 to 100 parts by mass with respect to 100 parts by mass of the rubber component. The tire rubber composition according to any one of claims 1 to 5, wherein the content of the emulsifier is 0.1 to 500 parts by mass with respect to 100 parts by mass of the solid content of the microfibrillated plant fiber. The tire rubber composition according to any one of claims 1 to 6, wherein the emulsifier is naturally derived. The tire rubber composition according to claim 7, wherein the emulsifier is lecithin and / or saponin. A tire produced using the tire rubber composition according to claim 1. Including a rubber component and microfibrillated plant fiber,
A tire rubber composition, wherein the microfibrillated plant fiber has an average fiber diameter of 1 nm or more and less than 20 nm. The tire rubber composition according to claim 10, wherein the microfibrillated plant fiber is cellulose microfibril. The tire rubber composition according to claim 10 or 11, wherein a content of the microfibrillated plant fiber is 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component. The tire according to any one of claims 10 to 12, wherein the microfibrillated plant fiber has a structure in which hydrogen atoms of some hydroxyl groups in cellulose microfibrils are substituted with a carboxyl group-containing group of a cyclic carboxylic acid anhydride. Rubber composition. The tire produced using the rubber composition for tires in any one of Claims 10-13. The tire according to claim 14, wherein the tire is a studless tire.