Natural rubber, rubber composition comprising natural rubber and method for producing same, and tire

Technical Field

The invention relates to a natural rubber, the natural rubber of the rubber composition and tire, in particular to have excellent resistance to cracking of the natural rubber, the natural rubber of the rubber composition and tire.

Background Art

Natural rubber is frequently used in the many fields, including industrial products such as tires, rubber band, rubber roller, the airbag (praders) and the mudguard, sports goods such as tennis, basketball, soccer and volleyball. In recent years, in the medical field and the field of biology similarly frequent use of natural rubber. Especially in the tire conditions, natural rubber is used as forming many of the module, such as a rubber tire tread, side walls, cord fabric level duplicate rubber the material of the glue filling and bead.

When the natural rubber used in the above-mentioned products such as tires, required for this natural rubber, particularly in regard to wear resistance and improved resistance to cracking.

The so far in the rubber is dissolved in an organic solvent such as tetrahydrofuran after (THF), pass through the filter filtering and separating the impurity such as the rubber component is not soluble in THF, and through the gel permeation chromatography GPC, based on standard calibrants measuring the relative molecular weight of the rubber as a process of gelation or macromolecule (multi-coupled) the molecular weight of the natural rubber of the measuring method. However, the above-mentioned measuring method includes natural rubber and diene series synthetic rubber containing ultra-high molecular weight polymer is such as a filter cut off and is not measured.

Furthermore, in recent years, by using the already proposed for natural rubber and a diene synthetic rubber structural analysis grading field class (hereinafter referred to as "FFF") equipment or FFF and multi-angle light scattering (hereinafter referred to as "MALS") detector, the measurement and analysis of natural rubber and a diene synthetic rubber of the absolute molecular weight of the high-order structure method (refer to valeant literature 1 to 3).

The present inventors have attempted to improve the above-mentioned measuring method, and by the following method to the analysis of natural rubber and diene series synthetic rubber a high-order structure, measurement and analysis of ultra-high molecular absolute molecular weight.

New measurement and analysis method is the following method, wherein in the 10,000 to 1,000,000G centrifugal separation under centrifugal acceleration of the rubber used for the measurement of the dissolved in tetrahydrofuran and rubber solution, and pass with the multi-angle light scattering detector is connected to measuring equipment of hierarchical field class contained in the solution of soluble component (refer to Patent document 1).

Literature of the prior art

Patent literature

Patent literature 1: Japanese Patent application opens the number especially 2012-122796

Valeant literature

Valeant literature 1 :   Research   Natural   of   Rubber Journal, 1997, vol.12 (3), section 154-165 page

Valeant literature 2: Macromolecules, 1995, 28, section 6354-6356 page

Valeant literature 3 :   Chem.Soc Bull.Korean, 2000, vol.21, No. 1, paragraph 69-74 page

Content of the invention

Problem to be solved by the invention

In the conventional natural rubber, rubber molecule not sufficiently producing high-molecular-weight compounds, such as cracking resistance is not satisfactory. Furthermore, conventional gelation natural rubber is a part of high-molecular, but having a high molecular weight high molecular absorptive components of ultra-high level, an adverse effect on gelation notably, thus the deterioration states rubber in the processability of the in the mixing process. Furthermore, by the above-mentioned rubber high molecular absorptive produce ultra-high level of dispersion of poor, and the wear resistance and the rupturing the deterioration bears.

The proposed by the inventor of the method for measurement and analysis of the rubber (FFF-MALS method) has gradually clarified by the above-mentioned rubber high molecular absorptive performance deterioration caused by ultra-high level problems.

The purpose of this invention is to offer a kind of keep processing and has excellent resistance to the rupturing and resisting frictional wear of a natural rubber, comprises the above-mentioned natural rubber and the rubber composition for the tire prepared using the same.

The programme applied to the solution of the problem

The present inventors have found that, by increasing the natural rubber in the improved high molecular weight component contained in the natural rubber of resisting frictional wear and cracking resistance, the absolute molecular weight of 5,000,000 or more high molecular weight component of the natural rubber to improve the above-mentioned characteristics to a large extent; on the other hand, the inventor has already found, contained in the natural rubber surrounds the absolute molecular weight more than 50,000,000 of a component of a ultra-high molecular weight, have processability degradation. Therefore, the inventor has already solve the above-mentioned problem.

In other words, natural rubber of the present invention, which is a natural rubber or natural rubber latex, including 15% more than the quality of the molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 and 40% of the following quality of molecular weight more than 50,000,000 ultra-high molecular weight of the component P2, and P1% and the quality of the P2 of the relationship between the quality of the % 1.5 × P1% ≥ P2 the quality of the mass %, the molecular weight of their respective measured by the following measuring method. In particular, P1% and the quality of the P2 of the relationship between the quality of the % P1% ≥ P2 the quality of the mass %, and the natural rubber preferably comprises 20% of the above quality P1. The natural rubber has the above-mentioned high-molecular weight component, the cracking resistance, abrasion resistance becomes more remarkable effects.

The rubber molecular weight measuring method, in the 10,000 to 1,000,000G centrifugal separation under centrifugal acceleration of the rubber solution, and the grading equipment field class with the multi-angle light scattering detector measuring the solution containing soluble component. The above-mentioned rubber molecular weight by a conventional method is different from the measurement of the gel permeation chromatography GPC based on standard calibrants measuring relative molecular weight of the method, the measuring method is the method of measuring absolute molecular weight.

In the present invention in the natural rubber, the natural rubber latex or natural rubber is preferably of gelation or process, and preferably reducing the natural latex or natural rubber water content to 40% of the following quality, and keep the 72 hours or more. Furthermore, the natural latex preferably by acid acid coagulation of the coagulant, the coagulant after adding the acid 8 hours to carry out dehydration processing.

The in the natural rubber of the present invention, is preferably added 16 parts by mass of the latex to skim of more than 100 parts by mass of natural rubber latex in the form of a solid.

The in the natural rubber of the present invention, the preferred cross-linking agent which is added to the natural rubber latex or natural rubber gelation or macromolecule. The above-mentioned gelation or producing high-molecular-weight compounds can be natural latex of the of the respective as described above with a preferably high molecular weight component P1 and the ultra-high molecular weight component P2 a molecular weight of, the natural latex will has excellent workability, resisting frictional wear and cracking resistance.

Natural rubber according to the present invention is characterized in that the production method of the, control natural latex or natural rubber to 40% of the following quality and keep the water content of 72 hours or more, by this preparation containing 15% more than the quality of the high molecular weight component P1 and 40% of the following quality of the ultra-high-molecular-weight component P2 of a natural rubber, and P1 the quality of the % P2 of the relationship between the quality of the % 1.5 × P1% ≥ P2 the quality of the mass %, the molecular weight of their respective through the above-mentioned measurement method is determined.

The natural rubber according to the present invention in the production method, the natural latex preferably by acid acid coagulation of the coagulant, the coagulant after adding the acid 8 hours to carry out dehydration processing. Furthermore, preferably add 16% more than the quality of the glue in the form of a solid cleaning latex to 100% quality natural latex in the form of a solid.

Furthermore, the invention includes natural rubber of the present invention the rubber composition of the present invention and using the above-mentioned rubber composition preparation of the tire. In the above-mentioned rubber composition and tire, using the above-mentioned natural rubber makes it possible to further improve the resistance to rupturing and wear resistance.

Effect of the invention

Natural rubber according to the present invention include a large amount of the high molecular weight component, has excellent resistance to the rupturing and resisting frictional wear, and because of the natural rubber comprises less ultra-high molecular weight component P2, thus inhibiting have processability degradation, to provide a stable natural rubber of excellent characteristics. The above makes it possible to provide excellent physical properties of natural rubber, and at the same time raise and the rubber composition using the natural rubber preparation of the physical properties of the tire.

Mode of execution

The following will illustrate the invention in detail.

According to the invention natural rubber comprises 15% more than the quality of the molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 and 40% of the following quality of molecular weight more than 50,000,000 of ultra-high molecular weight component P2, and P1% and the quality of the P2 of the relationship between the quality of the % 1.5 × P1% ≥ P2 quality of the quality %, preferably P1% ≥ P2 the quality of the mass %. In particular, the natural rubber preferably contains 20% more than the quality of the high molecular weight component P1 and 30% of the following quality of the molecular weight more than 50,000,000 of ultra-high molecular weight component P2.

The natural rubber has the above-mentioned high-molecular weight component, whereby the natural rubber to maintain processability suffices sufficiently , and has excellent resisting frictional wear and cracking resistance.

High molecular weight component P1 and P2 of the measuring method includes: dissolved in the organic solvent as an analysis target dissolution of natural rubber; in the 10,000 to 1,000,000G centrifugal separation under centrifugal acceleration of the rubber solution, the solution is from this component can be dissolved in the separation of components of the separation step of the method; and the use of the apparatus is connected as a molecular weight fractionation equipment FFF, as molecular weight and branched detector of the MALS detector or, if small angle laser light scattering RALLS LALLS and a right-angle laser light scattering, single-angle light scattering detector and viscosity detector of the apparatus, separating step in the analysis of soluble component in order to determine its molecular weight measuring step.

For dissolving organic solvent of natural rubber, can be any solvent, as long as the organic solvent-soluble natural rubber. In particular, the form can be used alone or as a mixture (THF) is selected from tetrahydrofuran, chloroform, toluene and cyclohexane of at least one. In the present invention, the use of having good dissolution capacity THF.

Taking into account a plurality of natural rubber according to the concentration of natural rubber, natural rubber in the addition amount of the organic solvent, the dissolution amount of sorbic acid 0.001-1% in the range of quality.

In the dissolving step, the natural rubber is added to the organic solvent, then storage 12 hours or more, to completely dissolve the natural rubber.

Centrifugal separation is conventional separation technology, used in the present invention in the 10,000 to 1,000,000G separated under the centrifugal acceleration of the method, the so-called ultra-centrifugal separation. Can only obtain said natural rubber solution contains ultra-high molecular weight component of the soluble component. Analysis has become can be maintained at ultra-high molecular weight component is included in the case of natural rubber, which has so far also can not be used for analysis.

In the above-mentioned separating step, of the 10,000 to 1,000,000G centrifugal acceleration within a fixed range, centrifugal separation of the rubber solution 10 to 300 minutes. The above-mentioned can make a soluble component in said solution with insoluble component separation. If the centrifugal acceleration less than 10,000G, the separation is not full. If the centrifugal acceleration exceed 1,000,000G, which causes the problem of durability of the container.

The centrifugal part of the can can be utilized under the vacuum and in the high-speed rotating the sample container under ultra-centrifugal separator for centrifugal separation.

Through a connection can be utilized as molecular weight grades FFF device of the equipment, as a molecular weight and branched detector such as detector or MALS LALLS (small angle laser light scattering) and RALLS (right-angle laser light scattering)  , and single-angle light scattering detector apparatus by the viscosity detector, analyzing the soluble component.

Through its FFF according to the diffusion rate of the solution of the difference between the molecular weight of the component in the hierarchical, and unlike conventional GPC analysis, the technical solution does not need to be filtered. In in FFF, in accordance with the molecular weight is small molecule having the sequence of a larger diffusion rate, the component of the elution solution.

Therefore, use of conventional GPC replaced FFF apparatus comprising a to the excluded so far ultra-high molecular weight component in the range of soluble component analysis, without filtering. In particular, preferably asymmetric flow FFF apparatus as FFF apparatus.

According to Debye curve (  plotting Debye), MALS detector to measure through the use of the corresponding molecular component FFF separation by the molecular weight distribution of the soluble component.

So far, by using in principle desired GPC and MALS obtained through the joint as measured by method GPC-MALS branching index, but in the case of natural rubber, because with long-chain comprising a large number of the branched component, the function of the grading and molecular weight are not suitable for the GPC, because of abnormal elution phenomenon, low-molecular-weight linear polymer and high-molecular weight of the branched polymer eluted at the same retention time, result is not capable of measuring branching index of wide molecular weight range. Therefore, in the natural rubber and comprises a large number of branched component of the condition of the rubber, the branching index is not to use a structure obtained by GPC-MALS analysis of factors.

In according to the invention natural rubber and natural rubber in the production method, the following only referred to as "the invention", the natural rubber is via gelation or macromolecule natural rubber or natural rubber latex and the obtained.

In the RSS rubber smoked sheet , according to natural rubber natural rubber in the conventional production of different level packaging standards of the International quality of the product (general term "green") levels in, clotting with acid is obtained after tapping the natural latex of the rubber component USS, and capstan, the solid rubber with a water-soluble non-rubber component separation, and in about 60 the drying [...] , smoked (smoked) 5 to 7 days. Furthermore, in the process classification rubber TSR, after tapping natural latex of the rubber component of the natural solidification (cup gel), crushing the solid rubber, washing with water, dewatering. Furthermore, in the above-mentioned solid rubber 110-140 the under [...] hot air drying for several hours.

In this invention, gelation or process through the natural rubber is naturally solidified immediately after tapping the natural latex, but through the following gelation or macromolecule processing of the natural rubber is preferred.

In the present invention, the acid for the natural latex coagulation, after adding the acid and the 8-hour period, preparing the rubber the dewatering treatment and/or the water content is controlled to 40% of the following quality, in order to the natural rubber gelation or macromolecule at least 72 hours or more to obtain natural rubber, is preferred. The above-mentioned dehydration processing and/or gelation or macromolecule processing which makes it possible to obtain comprises 15% more than the quality of the molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 and 40% of the following quality of molecular weight more than 50,000,000 of ultra-high molecular weight component P2 of natural rubber.

The acid can be used for preparing the organic acid or inorganic acid, such as formic acid and sulfuric acid can be cited as the representative example. The acid added to the latex to be processed, in order to control the the pH 5.0 in the range of, and in the particularly preferred at pH 3.0-4.8 in the range of.

In preparing the addition of the acid for 8 hours, in particular 6 hours, to the natural latex to dehydration processing and/or control to the water content is in the 40% of the following quality, preferably 30-5 quality within the range of %, and is stored at room temperature or aging at least 3 days (72 hours) or more, at the same time avoid direct sunlight.

When the acid-treated and/or dehydration treatment when used in too long and the time of gelation or process, storage or aging is too short, no access to include a large amount of high molecular weight component P1 of natural rubber, and unable to obtain wherein inhibition of ultra-high molecular weight component P2 increased natural rubber.

Furthermore, preferably in the 5 to 60 the temperature of [...] , more preferably room temperature storing natural rubber, at the same time avoid direct sunlight. The storage time is preferably in the 40 days, from the economic point of view, is not preferably longer gelation or macromolecule. Natural latex of the washing after storage, and by hot-air drying, obtain the natural rubber. In the 60 to 140 the under [...] the temperature of the hot air drying appropriate time.

In the present invention, through the 16 parts by mass of the above-mentioned rubber cleaning latex is added to 100 parts by mass of natural rubber latex solid form to gelation or polymer the natural latex and natural rubber obtained, is preferred. More preferably add 20 to 100 parts by mass of the rubber cleaning latex.

Add used for gelation or macromolecule processing glue cleaning latex, comprising which makes it possible to obtain 15% more than the quality of the molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 and 40% of the following quality of molecular weight more than 50,000,000 of ultra-high molecular weight component P2 of natural rubber.

The latex states the rubber to be clear through the natural latex is obtained by centrifugal separation of the by-product. Generally speaking, the latex condensate through the centrifugal separation step is the manufacture of commercial field latex. After the stabilization field latex, the continuous supply of the field latex to the centrifugal separator, and separated into a latex condensation stream and the known cleaning a glue rubber latex class the other. Usually, the condensation product containing about 60% of the quality of the rubber, the latex states the rubber to be clear comprising 3-6% of the quality of natural latex rubber and from other material.

In the present invention, the cross-linking agent is added to the natural rubber latex or natural rubber to gelation or macromolecule natural latex or natural rubber and natural rubber obtained, is preferred.

The cross-linking agent can be directly added to the natural rubber latex, then reaction to the polymer the natural latex, or the cross-linking agent can be added to pass through the coagulation, washing and drying is obtained by natural latex of a natural rubber, and the mechanical shear force is exerted on it, that is, the mixed natural latex, macromolecule from this natural latex.

For example, the raw materials and the natural rubber can be cross-linked in the apparatus of the application of sufficient mechanical shear force, natural rubber in a mechanical shear force is applied, from this it can be cross-linked (coupled) and polymer the natural rubber molecules. The above-mentioned so that a step can be reduced, by applying mechanical shear force and inhibit (mixed) due to excessive lowering of the molecular weight.

The above-mentioned mechanical shear force in a variety of mixing equipment that shearing and in the solid natural rubber material deformation, is applied to the solid natural rubber material force.

The extent of the above-mentioned mechanical shear force there should be no particular restriction, can be properly selected according to the purpose, preferably in order to at a preferably 10 to 10000 seconds^-1, more preferably 50 to 3000 seconds^-1 a shear rate within the range of applied shear force.

If the shear rate is less than 10 seconds^-1, the insufficient mechanical shear force, under certain circumstances, do not fully cross-linking reaction. If the shear rate is more than 10000 seconds^-1, in certain circumstances, the molecular weight of the natural rubber molecules accelerate reduced, thus deterioration heat build-up property. On the other hand, if the above-mentioned shear rate is in the range of than the above-mentioned more preferably, from the cross-linking reaction between the development and reduced molecular weight balance point of view, for the purposes of heat build-up, is advantageous.

The apparatus of the above-mentioned mechanical shear force applied there should be no particular restriction, can be properly selected according to the purpose, the device comprises for example a Bunbary mixer is representative of the closed double-shaft mixer, twin-shaft kneading apparatus and dry pre-breaker.

The cross-linking agent should not be any particular restriction, so long as the cross-linking agent is having at least two functional groups of the reaction with the rubber molecule of the compound, the functional group preferably has the rubber molecular polymerization reactivity and/or addition reactive (  reactable   and/or multi-coupling   addition). Based on 100 parts by mass of natural rubber latex (solid substance) or natural rubber component, the amount of said compound is preferably 0.01 to 3 parts by mass.

If the addition amount of the cross-linking agent of more than 3 parts by mass, the rubber is incremented in ultra-high molecular weight component P2, to the natural rubber adversely affect processability. From the above-mentioned view, the to states the recruitment 3 parts the following, preferably 2.5 portions of the following and more preferably 2.2 parts of the following. Furthermore, if the cross-linking agent added is less than 0.01 parts by mass, the rubber can not be fully macromolecule.

In the present invention, with polymerization reactive functional group and/or addition reactive functional group of the cross-linking agent should not be any particular restriction, so long as the cross-linking agent causes the rubber to rubber between the two-stage or three-stage structure of the cross-linked. The polymeric reactive functional group includes, for example, vinyl, the addition of reactive functional groups include, for example, hydrazidyl and mercapto group (thiol   group). The functional group can be the above-mentioned polymerization reactivity functional group and any combination of addition-reactive functional group. In particular, preferably two vinyl compounds, coal tar compounds and double-mercapto compound.

Said vinyl compound has two vinyl, and usually with the double bond in natural rubber molecule reaction.

Polymerization reactivity functional group of a linking compound such as divinyl compound depends on the amount of the polymerization initiator of the compound combination of the bonding between such as states the junction , other traction (drafting) and the like, so that they may increase the super-high-molecular of the rubber. Therefore, based on 100 parts by mass of natural rubber component, the use of the addition amount of the polymerization initiator is preferably 1.00 parts by mass of the following. In particular, in the preferably states the recruitment 0.05 to 0.5 parts by mass of the range.

If the addition amount of the polymerization initiator of more than 1.00 parts by mass, the rubber is incremented in ultra-high molecular weight component (P2), to the natural rubber adversely affect processability. Furthermore, if the polymerization initiator added is less than 0.05 parts by mass, the rubber can not be fully macromolecule.

Said vinyl compound having two vinyl or two containing vinyl (hereinafter referred to as Vn) of the group, by formula (Vn) 2R of said compound, and by making the having two or more vinyl or two or more compounds containing vinyl groups with mineral acid, having two or more dibasic acid compound, having two or more hydroxyl groups or with more than two binary salt (dibasic   salts) (amino or amido) of the compound obtained by the esterification of the compound, the two vinyl compound can be used, for example, is represented by the formula expressed: type Vn-(O=) S-(O=)-Vn, type Vn-O-(O=) C-R-C (O =)-O-Vn, formula Vn (O=) C-NH-R-NH-C (=O) Vn formula Vn (O=) C-O-R-O-C (=O) Vn.

Vn is vinyl or containing vinyl groups, can differ from one another. R such as a methylene, ethylidene and propylene of such as alkylene, alkyl asian link , phenylene, naphthylene, or by a combination of some of the above-mentioned group gets the carbon chain, for a total of R has 1 to 20 carbon atoms of the carbon chain. Furthermore, R can be oxygen, nitrogen, sulfur, halogen element and/or the carbon chain containing a substituent of the above-mentioned element in the carbon chain, as long as R is ordinarily and in practice can be of making and using the same.

Vinyl is directly substituted and is connected with the two vinyl compound include, for example, divinyl benzene and second ethylene naphthalin from.

Furthermore, are obtained by the vinyl ester bond of the compound or vinyl compounds include, for example, two vinyl sulfone, oxalic acid bis vinyl ester, vinyl ester adipate, azelaic acid two vinylester, sebacic acid two vinylester, vinyl ester acid di petrosilane , twelve acid divinyl ester, terephthalic acid ester, N, N '-methylene-bis-acrylamide and N, N' -an ethylene oxide dihydrogenmethylenebisphosphonate acrylamide.

Reactive functional group with addition of cross-linking agent include, for example, two amino compounds, dihydroxy compounds, coal tar compounds and double-mercapto compound, they and the rubber of the double bond in the molecule, such as carboxyl group carry out nucleophilic or electrophilic reaction. From the point of view of reactivity, preferably a dihydrazide compound and a double-mercapto compound.

The compound [...] by formula H₂ NNHC (=O)-R-C (=O)-NHNH2 expressed. R such as a methylene, ethylidene and propylene of such as alkylene, alkyl asian link , phenylene, naphthylene, or by a combination of some of the above-mentioned group gets the carbon chain, is provided with a R 1 to 20 carbon atoms of the carbon chain. Furthermore, R can be oxygen, nitrogen, sulfur, halogen element and/or the carbon chain containing a substituent of the above-mentioned element in the carbon chain, as long as R is ordinarily and in practice can be of making and using the same.

Specific compounds include, for example, coal tar, phthalic hydrazide, m-phthalic hydrazide, the terephthalic hydrazide, 1, 3-bis (hydrazine carbonyl ethyl (hydrazinocarboethyl))-5 isopropyl hydantoin, succinic acid dihydrazide, adipic acid dihydrazide, [...] , [...] , twenty acid dihydrazide, twelve acid dihydrazide, 7, 11-eighteen carbon diene -1, 18-dicarboxylic acid dihydrazide oxalate and coal tar.

For the double-mercapto compound having two mercapto or two containing mercapto (SH expressed by below) group, represented by formula R (SH)₂ expressed and in the rubber in the compound with high dispersibility.

The SH containing a sulfhydryl group or mercapto group, can differ from one another. R such as a methylene, ethylidene and propylene of such as alkylene, alkyl asian link , phenylene, naphthylene, or by a combination of some of the above-mentioned group gets the carbon chain, for a total of R has 1 to 20 carbon atoms of the carbon chain. Furthermore, R can be oxygen, nitrogen, sulfur, halogen element and/or the carbon chain containing a substituent of the above-mentioned element in the carbon chain, as long as R is ordinarily and in practice can be of making and using the same.

Specific double-mercapto compound include, for example, 2, 3-mercapto-1-propanol, an ethylene oxide dihydrogenmethylenebisphosphonate (mercapto acetate), meso -2, 3-dithiopurine acid and double (2-mercapto ethyl) ether.

The rubber composition of the present invention is comprising the above-mentioned natural rubber by mixing of the preparation of the rubber component. In the rubber composition of the invention includes the above-mentioned rubber component natural rubber, in addition, which can include conventional natural rubber and the various synthetic rubber. From the polymer or uniformly dispersible view of compatibility, it is preferred to use a diene series synthetic rubber.

A diene can be used include, for example, synthetic rubber, is selected from the group consisting of isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and styrene-isoprene copolymer rubber of at least one, and from the viewpoints of heat resistance, preferably in particular selected from the group consisting of isoprene rubber, styrene-butadiene copolymer rubber and butadiene rubber of at least one. In the present invention in the rubber composition, based on the total amount of the whole rubber component, the acquired natural rubber is in a content of 5 mass % or more, preferably 50 mass % or more. If the above-mentioned natural rubber content is smaller than 5 mass %, it can not be fully play the effect of the above-mentioned natural rubber.

The rubber composition of the present invention can be with such as carbon black and the fillers of the silicon dioxide, commonly used in compounding agent in the field of rubber industry such as softening agent, silane coupling agent, stearic acid, zinc oxide, vulcanization accelerator and appropriate selection of the vulcanizing agent blended, as long as they do not damage the effect of the present invention. Commercially available product obtained can be appropriately used in the above-mentioned compounding agent.

The rubber composition of the present invention can be through the above-mentioned natural rubber and if necessary the various appropriate selection of complexing agent mixing, mixing, heating and extruding to preparation.

The rubber of this invention of combination articles stable quality, with excellent resistance to cracking and wear resistance of the rubber composition.

Next, the tire of the present invention is characterized in that, using the above rubber composition used for any tire component. In the present invention, said tire component is preferably inflatable tire tread and sidewall. As described above in a rubber composition for tire tread in the tire of preparing, viscosity and molecular weight within the range of the natural rubber can be used as a rubber component, so can be kept for a long time the durability of the tire. In addition to the above rubber composition is used for any of its tire components, the tire of the present invention there is no specific limitation, the tire can be manufactured according to the traditional method.

Embodiment

The following reference examples and comparative examples in a more specific and detailed manner to clarify the invention, but the invention should not be limited to the following embodiment.

Preparation the following embodiment and comparison example of natural rubber shown in, and by adding the following table 1 of the invention shown in the, use of the natural rubber by preparing a rubber composition. The adoption of the following evaluation of the evaluation method for the physical properties of the rubber composition.

Table 1

* 1:CZ, N-cyclohexyl-2-benzothiazole sulfenamide

Evaluation method:

(1) high molecular weight component P1 and the ultra-high molecular weight component P2 measurement:

Added to the natural rubber sample THF, in order to make the said solution the concentration of the natural rubber in the 0.4 mass %. In storage 24 hours later, the use of stainless steel centrifugal tube, so that the above-mentioned solution in about 150,000G under the centrifugal acceleration of the ultra-centrifugal separation 1 hours, the solution to the soluble component and insoluble component separation.

Corresponding to the separation solution obtained can be dissolved in the supernatant fluid component, to two times with diluted THF, and utilize FFF-MALS measuring and analyzing said solution. The use of separately manufacturing   Gmbh Postnova AF2000 as FFF apparatus, Wyatt   Heleos   Technology Dawn manufacturing   Corporation of MALS detector and Postnova as   II of   Gmbh Model   PN3140 as RI detector. In the present circumstances, in order to said FFF apparatus-MALS detector-RI sequence of the detector is connected with the instrument.

(2) rubber composition for the evaluation of the physical properties of: mixing back door Nepal viscosity measurement method:

According to JIS   K   6300-1:2001, measuring 130 the under [...] with a Mooney viscosity of the rubber composition. The comparison example 1 with a Mooney viscosity of the rubber composition in the set to index is 100, and through the index shown other circumstances with a Mooney viscosity of the rubber composition. The higher the value, the poorer the processability of the rubber composition.

(3) the rubber composition for the evaluation of the physical properties of: tensile strength at break, Tb:

According to JIS   K   6301, measured at room temperature the elastic rubber composition. The greater the value that the better the cracking resistance. The comparison example 1 the elasticity of the rubber composition in the set to index is 100, and the other of the index showing an elasticity value.

(4) the rubber composition for the evaluation of the physical properties of: resisting frictional wear:

Using the Lambourn type wear testing machine determining the room temperature the lower sliding ratio is 25% the abrasion amount of the, and through the index shown its countdown, wherein the comparison example 1 in the abrasion loss of the rubber composition is set as 100. The greater the value, the better the abrasion resistance.

First of all, in the embodiments 1 to 11 and comparative example 1 to 2 in, preparing a rubber composition.

Embodiment 1

Containing the 600g the field latex solid substance 2000g into the equipped with a stirrer and a temperature control jacket is made of stainless steel of a reaction vessel, and will pre-through will be dissolved in 20 ml water by Kao   Corporation of producing 100 mg emulsifier Emulgen   1108 added to 3.0g divinyl benzene and preparation of the emulsion with 280 ml water is added to the field latex together. Stirring the mixture at room temperature for 30 minutes, at the same time through the bubbling by nitrogen for removing oxygen.

Furthermore, add the 1.0g tert-butyl hydroperoxide as the polymerization initiator and t-BHPO 1.0g four ethylene five amine TEPA as emulsion stabilizer, in order to make them in 40 the reaction under [...] 1 hour, thereby obtaining natural latex of the process.

The formic acid is added to the natural rubber latex, in order to control its pH to 4.7, the natural latex coagulation. Using scraper processing the solid material 5 times, then through the crusher, crushing. Furthermore, use of hot-air drier, in 110 the drying the solid substances under [...] 210 minutes, so as to obtain the natural rubber A. According to table 1 is shown in, using the natural rubber A preparing a rubber composition.

Relative to 100 parts by mass of the rubber, the amount of divinylbenzene 0.5 parts by mass (3/6=0.5), the amount of the polymerization initiator to 0.17 parts by mass (1/6=0.17).

Embodiment 2

In addition to embodiment 1 adding 14.4g divinyl benzene replace 3.0g other than divinylbenzene, carried out under the same conditions of preparation, natural rubber B obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 3

In addition to embodiment 1 adding 12.0g divinyl benzene replace 3.0g other than divinylbenzene, carried out under the same conditions of preparation, natural rubber C obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 4

In addition to embodiment 1 adding 6.0g divinyl benzene replace 3.0g other than divinylbenzene, carried out under the same conditions of preparation, natural rubber D obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 5

In addition to the embodiment 1 is added 3.0g vinyl acetate replaced adipate 3.0g other than divinylbenzene, carried out under the same conditions of preparation, natural rubber E obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 6

In addition to embodiment 1 adding 3.0gN, N '-methylene-bis-acrylamide replace 3.0g other than divinylbenzene, carried out under the same conditions of preparation, natural rubber F obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 7

The formic acid is added to the latex in order to control its pH to 4.7, the solidification field latex. Using scraper processing the above-mentioned solid material 5 times, then through the crusher, crushing. Using hot-air drier, in 110 the dry the [...] the above-mentioned solidified material 210 minutes, in order to get the 600g drying of the rubber, by Toyo   Seiki and   Seisaku-sho, Ltd. Manufacturing a plastomill, the drying of rubber and to 3.0g adipic acid in conjunction with the coal tar 90 the compounded [...] 90 seconds, thereby obtaining the natural rubber g.

Relative to 100 parts by mass of the rubber, the amount of adipic acid in coal tar 0.5 parts by mass (3/6=0.5).

Embodiment 8

In addition to the embodiment 7 is added 3.0g   2, 3-mercapto-1-propanol instead of 3.0g adipic acid other than coal tar, carried out under the same conditions of preparation, natural rubber H thus obtained. According to table 1 is shown in the composition, the rubber composition.

Embodiment 9

In addition to the embodiment 7 is added 3.0g   2, 3-dithiopurine succinic acid to replace 3.0g adipic acid other than coal tar, carried out under the same conditions of preparation, natural rubber I thus obtained. According to table 1 is shown in the composition, the rubber composition.

Embodiment 10

In addition to the embodiment 7 is added 3.0g an ethylene oxide dihydrogenmethylenebisphosphonate (mercapto acetate) replace 3.0g adipic acid other than coal tar, carried out under the same conditions of preparation, natural rubber J obtained thereby. According to table 1 is shown in the composition, the rubber composition.

Embodiment 11

In addition to the embodiment 7 is added 3.0g double (2-mercapto ethyl) the ether replaces 3.0g adipic acid other than coal tar, carried out under the same conditions of preparation, the K is a natural rubber. According to table 1 is shown in the composition, the rubber composition.

Comparative example 1

The formic acid is added to the latex in order to control its pH to 4.7, the natural latex coagulation (conventional solidification). Using scraper processing the solid material 5 times, then through the crusher, crushing. Furthermore, use of hot-air drier, in 130 the drying the solid substances under [...] (the conventional drying) 120 minutes, thereby obtaining natural rubber 1. According to table 1 is shown in the composition, the rubber composition.

Comparative example 2

In addition to embodiment 1 adding 20g divinyl benzene replace 3.0g other than divinylbenzene, carried out under the same conditions of preparation, thereby obtaining the natural rubber 2. According to table 1 is shown in the composition, the rubber composition.

Table 2 the embodiment shown in 1 to 11 and comparative example 1 to 2 for preparation of natural rubber of polymer using the above-mentioned natural rubber and preparation of the physical properties of each rubber composition.

Refer to table 2 shown in the results, in the embodiments 1 to 11 in the preparation of natural rubber, molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 of 15 mass % or more. Furthermore, molecular weight more than 50,000,000 of ultra-high molecular weight component P2 occupied 40% of the following quality. Furthermore, P1% and the quality of the P2 of the relationship between the quality of the % 1.5 × P1% ≥ P2 the quality of the mass %. Comparative example 1 preparation in the natural rubber is not full of full invention in the high molecular weight component P1 and ultra-high molecular weight component P2 ratio, while embodiment 1 to 11 for preparation of natural rubber to satisfy the proportion.

Furthermore, comparative example 2 preparation in the natural rubber is not of the fodder invention in the high molecular weight component P1 and the ultra-high molecular weight component P2 ratio, and when the cross-linking agent when the addition amount is too large, the ultra-high molecular weight component P2 increases. With the embodiment 1 to 11 compared with preparation of natural rubber, comparative example 2 preparation in the natural rubber has high Mooney viscosity, have processability degradation, and Tb has been observed that the wear resistance and the improvement of the (resistance to cracking).

Furthermore, in the embodiments 12 to 17 and comparative example 3 to 6 in the preparation of a natural rubber.

Embodiment 12

The formic acid is added to the natural rubber latex in order to make the natural latex solidification, the solidified of and after 6 hours, the solid rubber to a mechanical dewatering operation, in order to make its water content is 40% of the following quality. Furthermore, is not exposed to direct sunlight in the local, stored or aging the control water content is 40% of the following quality of the coagulated rubber 3 days, then washing the preparing rubber, and in 130 the hot air drying under [...] 2 hours, so as to obtain a natural rubber. According to table 1 is shown in the composition, the rubber composition.

Embodiment 13

The formic acid is added to the natural rubber latex in order to make the natural latex solidification, the solidified of and after 6 hours, the solid rubber to a mechanical dewatering operation, in order to make its water content is 40% of the following quality. Furthermore, is not exposed to direct sunlight in the local, stored or aging the control water content is 40% of the following quality of the coagulated rubber 7 days, then washing the preparing rubber, and in 130 the hot air drying under [...] 2 hours, thereby obtaining natural rubber b. According to table 1 is shown in the composition, the rubber composition.

Embodiment 14

The formic acid is added to the natural rubber latex in order to make the natural latex solidification, the solidified of and after 6 hours, the solid rubber to a mechanical dewatering operation, in order to make its water content is 40% of the following quality. Furthermore, is not exposed to direct sunlight in the local, stored or aging the control water content is 40% of the following quality of the coagulated rubber 35 days, then washing the preparing rubber, and in 130 the hot air drying under [...] 2 hours, so as to obtain c natural rubber. According to table 1 is shown in the composition, the rubber composition.

Embodiment 15

The formic acid is added to the natural rubber latex in order to make the natural latex solidification, the solidified of and after 6 hours, the solid rubber to a mechanical dewatering operation, in order to make its water content is 40% of the following quality. Furthermore, is not exposed to direct sunlight in the local, stored or aging the control water content is 40% of the following quality of the coagulated rubber 35 days, then washing the preparing rubber, and the 80 the hot air drying under [...] 24 hours, so as to obtain the natural rubber d. According to table 1 is shown in the composition, the rubber composition.

Embodiment 16

The 25 parts by mass of the rubber in the form of a solid cleaning latex is added to 100 parts by mass of natural rubber latex in the form of a solid, and solidifying the mixture using formic acid. Preparing washing the rubber, then in 130 the hot air drying under [...] 2 hours, thereby obtaining natural rubber sample e. According to table 1 is shown in the composition, the rubber composition.

Embodiment 17

The 50 parts by mass of the rubber in the form of a solid cleaning latex is added to 100 parts by mass of natural rubber latex in the form of a solid, and solidifying the mixture using formic acid. Preparing washing the rubber, then in 130 the hot air drying under [...] 2 hours, thereby obtaining natural rubber f. According to table 1 is shown in the composition, the rubber composition.

Comparative example 3

Formic acid the natural latex coagulation, washing said preparing rubber, then at 80 the hot air drying under [...] 24 hours, so as to obtain more natural rubber 3. According to table 1 is shown in the composition, the rubber composition.

Comparative example 4

In 60 the store under [...] comparative example 3 preparation of natural rubber in 7 days, in order to prepare the natural rubber 4. According to table 1 is shown in the composition, the rubber composition.

Comparative example 5

The formic acid is added to the natural rubber latex in order to make the natural latex solidification, the solidified of and after 6 hours, the solid rubber to a mechanical dewatering operation, in order to make its water content is 40% of the following quality. Furthermore, is not exposed to direct sunlight in the local, stored or aging the control water content is 40% of the following quality of the coagulated rubber 1 day, and then washing the preparing rubber, and in 130 the hot air drying under [...] 2 hours, so as to obtain more natural rubber 5. According to table 1 is shown in the composition, the rubber composition.

Comparative example 6

The formic acid is added to the natural rubber latex in order to make the natural latex coagulation, then preparing the rubber to a mechanical dewatering operation, and is not exposed to direct sunlight in the local storage or aging 35 days. Furthermore, washing said preparing rubber, and in 130 the hot air drying under [...] 2 hours, so as to obtain more natural rubber 6. According to table 1 is shown in the composition, the rubber composition.

Table 3 embodiment shown in 12 to 17 and comparative example 3 to 6 for preparation of natural rubber of polymer using the above-mentioned natural rubber and preparation of the physical properties of each rubber composition.

Refer to table 3 shown in the results, in the examples 12 to 17 for preparation of natural rubber, molecular weight of 5,000,000 to 50,000,000 of the high molecular component, P1 of 15 mass % or more. Furthermore, molecular weight more than 50,000,000 of ultra-high molecular weight component P2 occupied 40% of the following quality. With the comparison example 1 is the same as the condition of, comparative example 3 to 4 for preparation of natural rubber is not full of full invention in the high molecular weight component P1 and the ultra-high molecular weight component P2 ratio, and embodiment 12 to 17 for preparation of natural rubber to satisfy the proportion.

In the comparison example 3 in, when the constant low-temperature drying, observed that the gelation. However, most of the gelation lead to increased ultra-high molecular weight component. Furthermore, it has been found that, in comparative example 4 in, the low-temperature storage after drying the conventional natural rubber, also observed to clear gelation, however, most of the gelation also lead to increased ultra-high molecular weight component. In the comparison example 5 in, the mechanical dehydration step and aging step, however this time is not long enough, the result is a high molecular weight component is not sufficiently increase. Furthermore, in the comparison example 6 in, not to a mechanical dewatering step, carry out aging steps, this causes high molecular weight component does not increase.

Can be found that, compared with the conventional product, comparative example 3 to 6 preparation of rubber composition has poor processability, resistance to frictional wear with equilibrating cracking resistance. On the other hand, can be found that, in the embodiments 12 to 17 in, the processability in the state of the good, excellent wear resistance and resistance to cracking.

Industrial availability

According to the invention natural rubber has excellent processability, resistance to frictional wear with equilibrating cracking resistance, and has high industrial applicability.