JP2014051573A - Rubber composition, cured material and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition containing a lignin derivative and at least one of a natural rubber compound or a diene-based synthetic rubber compound, and excellent in elastic modulus, stress at break, further elongation at break, and to provide a cured material of the rubber composition, and to provide a tire manufactured by the rubber composition.SOLUTION: A rubber composition containing a lignin derivative having a carbon content measured by an elemental analysis method of 40 wt.% or more and a natural rubber compound or a diene-based synthetic rubber compound is used.

Description

  The present invention relates to a rubber composition, a cured product, and a tire.

  Many wood-based waste materials (biomass) such as bark, thinned wood, and building waste have been disposed of so far. However, protection of the global environment is becoming an important issue, and from this point of view, the reuse and recycling of wood-based waste materials are being considered.

The main components of common wood are cellulose derivatives, hemicellulose derivatives and lignin derivatives.
Among these, since lignin contained at a ratio of about 30% has a structure containing abundant aromatic rings, compositions and tires used as resin raw materials are disclosed (for example, see Patent Document 1). ).

  Further, since the lignin derivative has a structure rich in phenolic hydroxyl groups and alcoholic hydroxyl groups, compositions and tires used as tackifiers and antioxidants are disclosed (for example, patent documents). 2).

  However, a part of the lignin derivative obtained by dissolving the lignin derivative in the black liquor containing sodium hydroxide and sodium sulfide and recovering the lignin derivative from the black liquor in which the lignin derivative is dissolved is sulfonated. There was a possibility that the mechanical strength of the rubber composition was lowered (for example, see Patent Document 1).

  In addition, a lignin derivative containing abundant polar groups such as phenolic hydroxyl groups and alcoholic hydroxyl groups may deteriorate the appearance of the rubber composition (see, for example, Patent Document 2).

  Thus, the hardened | cured material of the rubber composition which used the lignin derivative has a possibility that mechanical strength may fall and hardness may be impaired or an external appearance may be impaired. In addition, the tire obtained by molding such a rubber composition may be impaired in the strength of the tire.

Special table 2011-520208 gazette JP-A-5-98082

  An object of the present invention is to provide a rubber composition having a high elastic modulus, a high stress at the time of cutting, and a high elongation at the time of cutting, a cured product of the rubber composition, and a tire manufactured by the rubber composition. is there.

Such an object is achieved by the present inventions (1) to (10) below.
(1) A rubber composition containing a lignin derivative (A) and at least one of a natural rubber compound or a diene synthetic rubber compound (B), wherein the lignin derivative (A) is measured by elemental analysis. A rubber composition having a carbon content of 40% by weight or more.

  (2) The rubber composition according to (1), wherein the lignin derivative (A) has a hydroxyl group equivalent of 150 g / eq or more.

  (3) The rubber composition according to either (1) or (2), wherein the lignin derivative (A) is obtained by treating biomass with subcritical water.

  (4) The lignin derivative (A) contains one having a polystyrene-equivalent number average molecular weight of 200 to 2000 measured by gel permeation chromatography (GPC) analysis. The rubber composition in any one.

  (5) The lignin derivative (A) is an integral value of 0.0 to 6.0 ppm excluding the integral value derived from the solvent and the internal standard substance when a 1% by weight heavy dimethyl sulfoxide solution is measured by 1H-NMR. And an integral value of 6.0 to 8.0 ppm, any one of (1) to (4), wherein the ratio [aliphatic 1H integral value / aromatic 1H integral value] is 1.0 to 10.0. The rubber composition as described in 2.

  (6) The content of at least one of the natural rubber or the diene synthetic rubber (B) is 100 to 10,000 parts by weight with respect to 100 parts by weight of the lignin derivative (A). The rubber composition as described.

  (7) The rubber composition according to any one of (1) to (6), which further contains a filler (C).

  (8) The rubber composition according to (7), wherein the filler (C) contains one or more selected from the group consisting of carbon black, silica, and alumina.

  (9) A cured product obtained by curing the rubber composition according to any one of (1) to (8).

  (10) A tire obtained by molding the rubber composition according to any one of (1) to (8).

  According to the present invention, by using a rubber composition having a lignin derivative and at least one of a natural rubber compound or a diene synthetic rubber compound, the elastic modulus is high, the stress at cutting is high, and the elongation at cutting is further increased. Can provide a rubber composition, a cured product of the rubber composition, and a tire manufactured by the rubber composition.

  Hereinafter, the rubber composition of the present invention, the cured product of the rubber composition, and the tire produced from the rubber composition will be described in detail based on preferred embodiments.

  The rubber composition of the present invention is a rubber composition containing a lignin derivative (A) and at least one of a natural rubber compound or a diene synthetic rubber compound (B), wherein the lignin derivative (A) is: The carbon content measured by elemental analysis is 40% by weight or more.

  The cured product of the present invention is obtained by curing a rubber composition. The tire of the present invention can be obtained by molding a rubber composition.

  Such a rubber composition improves moldability in various molding methods and can mold a complicated shape. For this reason, the cured product of such a rubber composition has a high elastic modulus, a high stress at the time of cutting, and a high elongation at the time of cutting. Moreover, the cured product of such a rubber composition can produce a tire excellent in durability and appearance.

<Rubber composition>
Hereinafter, each component of the rubber composition will be sequentially described.

(Lignin derivative (A))
First, the lignin derivative (A) will be described. A lignin derivative is a main component which forms the skeleton of a plant body with cellulose and hemicellulose, and is one of the most abundant substances in nature. The lignin derivative (A) is a compound having a phenol derivative as a unit structure, and this unit structure has a chemically and biologically stable carbon-carbon bond or carbon-oxygen-carbon bond. Less susceptible to degradation and biological degradation. Therefore, the lignin derivative (A) is useful as a resin raw material.

The lignin derivative (A) used in the present invention has a carbon content measured by elemental analysis of 40% by weight or more. As the elemental analysis method, a combustion method used for elemental analysis of organic substances can be used. Specifically, the lignin derivative (A) is heated to high temperature and oxidized in a mixed gas stream of oxygen and helium, so that carbon is carbon dioxide and hydrogen is water among the constituent elements of the lignin derivative (A). Nitrogen is converted into nitrogen oxide, and so on, so that the elements are converted into the corresponding oxides. By quantifying these, the ratio of each element can be calculated.
The oxygen content contained in the lignin derivative (A) is determined by thermally decomposing the lignin derivative (A) in a helium gas stream, converting the generated oxygen into carbon monoxide with a carbon catalyst, The oxygen content can be calculated by quantifying.

  The carbon content is 40% by weight or more, preferably 50% by weight or more, and particularly preferably 60% by weight or more. The upper limit of the carbon content is not particularly limited, but is practically preferably 90% by weight or less. When the carbon content is in the above-described range, the lignin derivative (A) has high hydrophobicity, so that the compatibility with a natural rubber compound or diene synthetic rubber compound (B) having relatively high hydrophobicity described later is improved, The amount of heat generated when producing the rubber composition can be kept low. By suppressing the heat generation amount low, deterioration of the rubber composition due to heat generation can be suppressed, and moldability can be improved. The cured product of the rubber composition has a high elastic modulus and excellent hardness. When the said carbon content is less than the said lower limit, there exists a possibility that the external appearance of hardened | cured material may be impaired because of the moldability fall by a compatibility fall. Moreover, when the said carbon content exceeds the said upper limit, since hydrophobicity is very high, there exists a possibility that the workability | operativity in the mixing process with the other component of a rubber composition may be impaired.

  Further, when the rubber composition of the present invention is used for tire applications, the rubber on the tire surface contacts the road surface and is deformed by repeated vibrations received from the road surface. It is known that when the thermal energy generated by this deformation is large, the fuel consumption is reduced. The frequency of repeated deformation at the time of traveling corresponds to 10 to 100 Hz, and it is known to improve the fuel efficiency of the tire by reducing tan δ which is one of viscoelastic characteristics in this frequency range. By setting the carbon content contained in the lignin derivative (A) within the above range, the lignin derivative (A) and the natural rubber compound or the diene synthetic rubber compound (B) contained in the rubber composition of the present invention , And the tan δ of the viscoelastic property can be reduced. As a result, the heat energy generated by repeated deformation can be kept small, so that energy loss can be kept low and the fuel efficiency of the tire can be enhanced.

The lignin derivative (A) used in the present invention preferably has a hydroxyl group equivalent of 150 g / eq or more. The hydroxyl group equivalent can be measured, for example, by the following method. In a stoppered Erlenmeyer flask, 1.0 g of the lignin derivative (A) sample and 4.0 g of a mixed solution of acetic anhydride / pyridine (1/3 volume ratio) were dissolved, and this solution was kept at 60 ° C. for 3 hours. Add 1 ml of pure water. The solution thus obtained is titrated with a 0.1 mol / L NaOH aqueous solution with pH = 10 as the end point, and the hydroxyl equivalent can be determined by the following formula.
Hydroxyl equivalent (g / eq) = 1000 * W / (((TB * f * S / SB)-(T * f)) * N)
The meaning of each symbol in the formula is as follows.
W: Sample weight (g)
TB: Blank titration (ml)
SB: Amount of blank acetic anhydride-pyridine mixture (g)
T: Titration volume with sample (ml)
S: Amount of acetic anhydride-pyridine mixed solution added with sample (g)
f: Factor of standard aqueous sodium hydroxide solution
N: Normality of sodium hydroxide standard aqueous solution

The hydroxyl group equivalent is preferably 150 g / eq or more, more preferably 200 g / eq or more. The upper limit of the hydroxyl group equivalent is not particularly limited, but is preferably 5000 g / eq or less for practical use. When the hydroxyl group equivalent of the lignin derivative (A) is in the above range, the amount of hydroxyl group is small, so when vulcanizing the rubber composition, the vulcanization delay can be reduced, and the cured product of the rubber composition can be reduced. Cutting stress can be improved. Further, when the hydroxyl group equivalent of the lignin derivative (A) is in the above-mentioned range, the amount of hydroxyl groups is small, so that the hydrophobicity is increased, and a relatively highly hydrophobic natural rubber compound or diene-based synthetic rubber compound (B) described later. ), The tan δ at a frequency of 10 to 100 Hz of the viscoelastic property of the rubber composition can be lowered, and when the rubber composition is used as a tire, the tire is repeatedly deformed during running. The loss of heat energy lost can be suppressed, and the fuel efficiency of the tire can be improved.
When the hydroxyl group equivalent is less than the lower limit, the appearance of the cured product may be impaired due to a decrease in moldability due to a decrease in compatibility. Moreover, when the said hydroxyl equivalent exceeds the said upper limit, since hydrophobicity is very high, there exists a possibility that the workability | operativity in the mixing process with the other component of a rubber composition may be impaired.

  The lignin derivative (A) used in the present invention is preferably obtained by decomposing biomass. Biomass is a plant or a processed product of a plant, and these are formed by capturing and fixing carbon dioxide in the atmosphere in the process of photosynthesis, and thus contribute to the suppression of the increase in carbon dioxide in the atmosphere. For this reason, it can contribute to suppression of global warming by utilizing biomass industrially.

  Examples of the treatment method for decomposing biomass used in the present invention to obtain a lignin derivative (A) include, for example, a method of treating a plant or a processed plant product with a chemical, a method of hydrolyzing, a steam explosion method, and a supercritical water treatment. Method, subcritical water treatment method, mechanical treatment method, cresol sulfate method, pulp production method, and the like. From the viewpoint of environmental load, a steam explosion method, a supercritical water treatment method, a subcritical water treatment method, and a mechanical treatment method are preferred. From the viewpoint of the purity of the obtained lignin derivative (A), the steam explosion method and the subcritical water treatment method are more preferable.

  Specific examples of the lignin derivative (A) include a guaiacylpropane structure represented by the following formula (1), a syringylpropane structure represented by the following formula (2), and 4-hydroxyphenylpropane represented by the following formula (3). Examples include the structure. From conifers, mainly guaiacylpropane structures, from broadleaf trees, mainly guaiacylpropane structures and syringylpropane structures, and from herbs, mainly guaiacylpropane structures, syringylpropane structures, and 4-hydroxy Each phenylpropane structure is extracted.

  Further, the lignin derivative (A) in the present invention is preferably one in which at least one of the ortho-position and para-position of the aromatic ring is unsubstituted with respect to the hydroxyl group. Such a lignin derivative (A) is excellent in reactivity because it contains many reaction sites where the curing agent acts by electrophilic substitution reaction to the aromatic ring, and steric hindrance can be reduced in the reaction with a hydroxyl group. It becomes.

  In addition to the above basic structure, the lignin derivative (A) may be a lignin derivative (A) having a functional group (lignin secondary derivative).

  The functional group possessed by the lignin secondary derivative is not particularly limited, but for example, those in which two or more of the same functional groups can react with each other or those capable of reacting with other functional groups are suitable. Specific examples include an epoxy group, a methylol group, a vinyl group having a carbon-carbon unsaturated bond, an ethynyl group, a maleimide group, a cyanate group, and an isocyanate group. Of these, the lignin derivative (A) having a methylol group introduced (methylolated) is preferably used. Such a lignin secondary derivative undergoes self-crosslinking by a self-condensation reaction between methylol groups, and a cured product having a particularly homogeneous and rigid skeleton and a particularly high elastic modulus is obtained.

In addition, the lignin derivative (A) in the present invention preferably has a polystyrene-equivalent number average molecular weight of 200 to 2000, as measured by gel permeation chromatography (hereinafter also referred to as GPC), and is 300 to 1800. Those are more preferred. Such a lignin derivative (A) having a number average molecular weight has a higher degree of compatibility between its reactivity (curability) and compatibility. Therefore, a cured product having both a high tensile modulus at cutting and a high elastic modulus after curing can be obtained.
In addition, since the molecular weight is low when the number average molecular weight is below the lower limit, elongation at break may be reduced. On the other hand, when the average molecular weight exceeds the upper limit, workability in the mixing step for producing the rubber composition may be deteriorated.

An example of a method for measuring the molecular weight by the gel permeation chromatography will be described.
The measurement sample is prepared by dissolving the lignin derivative (A) of the present invention in a solvent. The solvent used at this time is not particularly limited as long as it can dissolve the lignin derivative (A), but for example, tetrahydrofuran is preferable from the viewpoint of measurement accuracy of gel permeation chromatography.
Next, “TSKgelGMMHXL (manufactured by Tosoh)” and “G2000HXL (manufactured by Tosoh)”, which are organic general-purpose columns filled with a styrene polymer filler, are connected in series to the GPC system “HLC-8320GPC (manufactured by Tosoh)”. To do.
200 μL of the above measurement sample is injected into this GPC system, and the eluent tetrahydrofuran is developed at 1.0 mL / min at 40 ° C., and is retained using differential refractive index (RI) and ultraviolet absorbance (UV). Measure time. The number average molecular weight of the lignin derivative (A) can be calculated from a calibration curve showing the relationship between the retention time and molecular weight of standard polystyrene prepared separately.
The molecular weight of the standard polystyrene used for preparing the calibration curve is not particularly limited. For example, the number average molecular weight is 427,000, 190,000, 96,400, 37,900, 18,100. Standard polystyrene (manufactured by Tosoh) of 10,200, 5,970, 2,630, 1,050 and 500 can be used.

In addition, the lignin derivative (A) in the present invention is 0.0 to 6.0 ppm excluding the integral value derived from the solvent and the internal standard substance when a 1% by weight heavy dimethyl sulfoxide solution is measured by ¹ H-NMR. The ratio of the integral value and the integral value of 6.0 to 8.0 ppm [aliphatic 1H integral value / aromatic 1H integral value] is preferably 1.0 to 10.0, and preferably 1.5 to 9. 0 is more preferable. Thereby, the compatibility of the aliphatic structure part in a lignin derivative (A) and the aliphatic part with the natural rubber or diene rubber compound (B) mentioned later improves more. As a result, a cured product excellent in tan δ is obtained.
In addition, when the said ratio is less than the said lower limit, there exists a possibility that a moldability may fall. On the other hand, when the ratio exceeds the upper limit, the appearance may be impaired.

An example of the ¹ H-NMR measurement method will be described.
The lignin derivative (A) is dissolved in deuterated dimethyl sulfoxide to prepare a 1% by weight measurement sample. The heavy dimethyl sulfoxide used at this time is not particularly limited, but one containing 0.1% by weight of tetramethylsilane as an internal standard substance can be used.
Next, the measurement sample is put up to a height of 4 cm from the bottom of a 5 mmφ solution ¹ H-NMR measurement sample tube, and “JNM-ECA400 superconducting FT-NMR apparatus (manufactured by JEOL RESONANCE)” is used for 10-20 Hz. The sample is irradiated with a pulse at 40 ° C. while rotating at a speed, and free induction decay (FID), which is a ¹ H NMR signal, is detected. This free induction decay (FID) is Fourier transformed (FT) to obtain a ¹ H-NMR spectrum.
The peak derived from tetramethylsilane in the obtained spectrum is set to 0.00 ppm, and it is confirmed that a peak derived from a component in which a part of deuterated dimethyl sulfoxide is ¹ H is observed at 2.50 ppm.
In heavy dimethyl sulfoxide having high hygroscopicity, a peak derived from water may be broadly observed in the range of 3.0 to 4.0 ppm. In addition, when acetone is used in the step of taking out the lignin derivative (A) from biomass, a sharp peak derived from acetone remaining in the vicinity of 2.09 ppm may be observed. In the case where water, residual solvent such as acetone, and tetramethylsilane are used as the internal standard substance as described above, the integrated value of 0.0 to 6.0 ppm is excluded except for the integrated value of the peak derived therefrom, The ratio of the integrated value of 0.0 to 8.0 ppm [aliphatic 1H integrated value / aromatic 1H integrated value] can be calculated.

In addition, since aromatic protons and aliphatic protons generate peaks at distant positions in the chemical shift spectrum of ¹ H-NMR analysis, peaks can be separated, and peak identification and integral calculation are performed. be able to.

  Note that the integrated value of the peak attributed to the aromatic proton and the integrated value of the peak attributed to the aliphatic proton described above can be adjusted according to the biomass treatment conditions. For example, it is considered that the integrated value of the peak attributed to aromatic protons tends to increase by increasing the processing temperature and processing pressure of biomass or increasing the processing time.

  A part of the lignin derivative (A) of the rubber composition of the present invention may be replaced with other resin components. Specific examples include an epoxy resin, a phenol resin, a furan resin, a urea resin, and a melamine resin. By including these resin components, the relative melt viscosity of the resin components is lowered, so that the moldability of the rubber composition is improved. In addition, when these resin components are included, it is adjusted so that the content of the lignin derivative (A) is preferably 50% by mass or more, more preferably 60% by mass or more.

(Natural rubber compound or diene synthetic rubber compound (B))
Next, the natural rubber compound or the diene synthetic rubber compound (B) (hereinafter also referred to as rubber compound (B)) will be described.

  The rubber compound (B) can impart elongation at break to the rubber composition.

The natural rubber compound of the rubber compound (B) can be obtained, for example, by the following method. The sap collected from the rubber tree is filtered, and a water-soluble ammonium salt such as diammonium hydrogen phosphate or ammonium sulfate is added to the obtained latex.
Next, the mixture is stirred at 10 to 60 ° C. for 0.1 to 24 hours to reduce the content of metal elements such as magnesium and iron contained in the latex. If such a metal element is contained in a relatively large amount, the vulcanization rate may be reduced. The amount of the water-soluble ammonium salt added is not particularly limited, but 0.1 to 10% by weight based on the weight of solids in the latex is a decrease in the content of the metal element and the man-hours for removing the water-soluble ammonium. , From the viewpoint of both.
Next, the natural rubber compound of the said rubber compound (B) can be obtained by spraying the latex which reduced metal content to a pulse combustor, and making it dry. Drying is preferably performed by spraying into a drying chamber of 40 ° C. or higher and 100 ° C. or lower.

    The diene-based synthetic rubber compound of the rubber compound (B) is obtained by polymerization using a compound having two carbon-carbon double bonds (hereinafter also referred to as a diene monomer) as a polymerization monomer. Can do.

  Examples of the diene monomer include butadiene and isoprene, from the viewpoint of polymerization reactivity and availability, and at least one selected from these groups can be used. From the viewpoint of elongation at break, butadiene is preferred.

  In addition to the diene monomer, a compound having a carbon-carbon unsaturated bond may be used as the polymerization monomer. For example, alkene compounds such as ethylene, propylene, and butene, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, acrylates and methacrylates, vinyl propionate, styrene, acrylonitrile, etc. At least one selected from these groups can be used.

  Examples of the polymerization method include a radical polymerization method, a cationic polymerization method, and an anionic polymerization method, and it is preferable to use a radical polymerization method from the viewpoint of workability of the reaction.

  Examples of the diene synthetic rubber compound of the rubber compound (B) thus obtained include, for example, butadiene rubber, isoprene rubber, butadiene-styrene rubber, butadiene-isoprene rubber, isoprene-styrene rubber, isoprene-butadiene-styrene. Examples thereof include rubber and butadiene-styrene. Among these, isoprene rubber, butadiene rubber, butadiene-styrene rubber, and butadiene-nitrile rubber are preferable from the viewpoint of elongation at break, and butadiene rubber and butadiene-styrene rubber are more preferable from the viewpoint of achieving both elastic modulus and elongation at break. .

    The content of the rubber compound (B) is not particularly limited, but is preferably 100 parts by weight or more and 10000 parts by weight or less with respect to 100 parts by weight of the lignin derivative (A), and 200 parts by weight. The amount is more preferably 5000 parts by mass or less, still more preferably 300 parts by weight or more and 2000 parts by mass or less. When the addition amount is in the above range, the elongation at break is excellent.

(Filler (C))
Next, the filler (C) will be described.

The rubber composition of the present invention may contain a filler (C). When the filler (C) is added, examples of the filler (C) include talc, calcined clay, unfired clay, mica, silicates such as glass, oxides such as titanium oxide and alumina. , Magnesium silicate, fused silica (fused spherical silica, fused crushed silica), silicon compounds like crystalline silica, carbonates like calcium carbonate, magnesium carbonate, hydrotalcite, oxides like zinc oxide, magnesium oxide , Hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate, boric acid Borate such as calcium and sodium borate, aluminum nitride, boron nitride, silicon nitride In addition to inorganic fillers such as nitride powder, glass fiber, carbon fiber, carbon black, etc., wood powder, pulp ground powder, cloth ground powder, thermosetting resin cured powder, aramid fiber, Examples include organic fillers such as talc.
Among these, as the filler (C), a group consisting of carbon black, silica, alumina, aluminum hydroxide, calcium carbonate, titanium oxide, magnesium silicate, talc, zinc oxide, and magnesium oxide is easily available. Those containing one or more selected from the above are preferably used, and carbon black, silica, and alumina are more preferable from the viewpoints of both availability and elastic modulus. These fillers can reduce the expansion coefficient of the cured product of the rubber composition.

When the filler (C) is contained, the content thereof is preferably 100 to 10000 parts by mass, more preferably 150 to 5000 parts by mass with respect to 100 parts by mass of the lignin derivative (A). More preferably, it is 250 to 3000 parts by mass.
When the content rate of a filler is less than the said lower limit, there exists a possibility that the expansion coefficient of the hardened | cured material of a rubber composition cannot fully be reduced. On the other hand, when the filler content exceeds the upper limit, the proportion of the filler is too high, and the moldability of the rubber composition may be reduced.

  Moreover, it is preferable that the average particle diameter of a filler (C) is about 0.1-500 micrometers, and it is more preferable that it is about 0.2-300 micrometers. When the average particle diameter of the filler is within the above range, the cured product of the rubber composition is highly compatible with a low expansion coefficient and excellent moldability. The average particle size of the filler refers to the particle size of the powder distributed in 50% of the cumulative volume in the particle size distribution of the filler.

  Moreover, as a shape of a filler (C), flake shape, dendritic shape, spherical shape, fibrous shape etc. are mentioned, for example, It does not specifically limit.

  In addition, when a filler (C) is fibrous, it is preferable that it is a fiber diameter of 0.5-100 micrometers and fiber length about 1-50 mm.

  The rubber composition of the present invention may contain a crosslinking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, and the like, as necessary, in addition to the above components.

(Crosslinking agent)
Next, the crosslinking agent will be described.

  If necessary, a crosslinking agent can be added to the rubber composition of the present invention. When a crosslinking agent is added, the crosslinking agent is not particularly limited as long as it can crosslink with the lignin derivative (A) or the rubber compound (B), and both, but is represented by the following formula (4). Those containing compounds are preferred.

_{Z- (CH 2 OR) m (} 4)
[Z in Formula (4) is any one of a melamine residue, a urea residue, a glycolyl residue, an imidazolidinone residue, and an aromatic ring residue. Moreover, m represents the integer of 2-14. R is independently an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. However, -CH ₂ OR, the nitrogen atom of the melamine residues, the nitrogen atom of the primary amino groups of the urea residues, the nitrogen atom of the secondary amino group of the glycolyl residues, the secondary amino group of the imidazolidinone residues It is directly bonded to either the nitrogen atom or the carbon atom of the aromatic ring residue. ]

  A rubber composition containing such a compound is excellent in mechanical properties after curing, and contributes to improvement in durability and appearance of the cured product. This is because the compound represented by the above formula (4) contained in the cross-linking agent can form a polyfunctional cross-linking point, so that the lignin derivative (A) is cross-linked with high density and uniformity, and is homogeneous and rigid. This is because a simple skeleton is formed. The rigid skeleton improves the mechanical properties and durability (boiling resistance, etc.) of the cured product, and also suppresses the occurrence of blisters and cracks, thereby improving the appearance of the cured product.

In addition, as described above, —CH ₂ OR is a nitrogen atom of a melamine residue, a nitrogen atom of a primary amino group of a urea residue, a nitrogen atom of a secondary amino group of a glycolyl residue, or 2 of an imidazolidinone residue. Directly bonded to either the nitrogen atom of the primary amino group or the carbon atom of the aromatic ring residue, but two or more “—CH ₂ OR” are bonded to the same nitrogen atom or carbon atom. In this case, it is preferable that “R” contained in at least one “—CH ₂ OR” is an alkyl group. Thereby, a lignin derivative (A) can be bridge | crosslinked reliably.

  In this specification, the melamine residue refers to a group having a melamine skeleton represented by the following formula (A).

  In this specification, the urea residue refers to a group having a urea skeleton represented by the following formula (B).

  In this specification, the glycolyl residue refers to a group having a glycolyl skeleton represented by the following formula (C).

  In the present specification, the imidazolidinone residue refers to a group having an imidazolidinone skeleton represented by the following formula (D).

  In this specification, an aromatic ring residue refers to a group having an aromatic ring (benzene ring).

  Moreover, especially as a compound represented by the said Formula (4), the compound represented by either of following formula (5)-(8) is used preferably. These react with the crosslinking reaction points on the aromatic ring contained in the phenol skeleton in the lignin derivative (A) to reliably crosslink the lignin derivative (A) and self-crosslink by self-condensation reaction between functional groups. Arise. As a result, a cured product having a particularly homogeneous and rigid skeleton and excellent in mechanical properties, durability and appearance can be obtained.

［式（５）中、ＸはＣＨ₂ＯＲまたは水素原子であり、Ｒは独立して炭素数１〜４のアルキル基または水素原子である。また、ｎは１〜３の整数を表す。］

Wherein (5), X is CH ₂ OR or a hydrogen atom, R is independently an alkyl group or a hydrogen atom having 1 to 4 carbon atoms. N represents an integer of 1 to 3. ]

［式（６）中、Ｒは独立して炭素数１〜４のアルキル基または水素原子である。］

[In Formula (6), R is a C1-C4 alkyl group or a hydrogen atom independently. ]

［式（７）中、Ｒは独立して炭素数１〜４のアルキル基または水素原子である。］

[In Formula (7), R is a C1-C4 alkyl group or a hydrogen atom independently. ]

［式（８）中、Ｒは独立して炭素数１〜４のアルキル基または水素原子である。］

[In formula (8), R is a C1-C4 alkyl group or a hydrogen atom independently. ]

  As the compound represented by the above formula (5), a compound represented by the following formula (9) or (10) is particularly preferably used. These react with a crosslinking reaction point on the aromatic ring contained in the phenol skeleton in the lignin derivative to particularly surely crosslink the lignin derivative and cause self-crosslinking by self-condensation reaction between functional groups. As a result, a cured product having a particularly uniform and rigid skeleton and excellent mechanical properties, durability and appearance can be obtained.

［式（９）中、ｎは１〜３の整数を表す。］

[In formula (9), n represents the integer of 1-3. ]

［式（１０）中、ｎは１〜３の整数を表す。］

[In Formula (10), n represents the integer of 1-3. ]

  The cross-linking agent may contain at least one compound of hemisamethylenetetramine, quinuclidine, and pidgin instead of or together with the compound represented by the formula (4). . A cured product containing such a cross-linking agent has excellent mechanical strength and high durability and appearance. This is because hexamethylenetetramine, quinuclidine and pidine crosslink the lignin derivative (A) with high density and uniformity to form a homogeneous and rigid skeleton.

  In addition, the crosslinking agent may contain a crosslinking agent component other than the above-mentioned compound, but even in that case, the amount added is preferably less than that of the above-mentioned compound. Examples of the cross-linking agent component other than the above compound include, for example, orthocresol novolac epoxy resin, bisphenol A type epoxy resin, epoxidized glycerin, epoxidized linseed oil, epoxy resin such as epoxidized soybean oil, hexamethylene diisocyanate, toluene diisocyanate. Isocyanate compounds, compounds that can be cross-linked by electrophilic substitution reaction on aromatic rings of lignin derivatives, aldehydes such as formaldehyde, acetaldehyde, paraformaldehyde, furfural, aldehyde sources such as polyoxymethylene, hexamethylenetetramine In addition, a known cross-linking agent such as a resol-type phenol resin or a compound that can be cross-linked by electrophilic substitution reaction with respect to the aromatic ring of a lignin derivative can be used. And it is preferable that the content rate of the said compound in a crosslinking agent is 80 mass% or more before bridge | crosslinking reaction. Moreover, it is preferable that the said compound is 5-60 mass parts with respect to 100 mass parts of lignin derivatives (A), and it is more preferable that it is 10-50 mass parts.

(Vulcanizing agent)
Next, the vulcanizing agent will be described.

  A vulcanizing agent can be added to the rubber composition of the present invention as necessary. When adding a vulcanizing agent, it is preferable to use sulfur as the vulcanizing agent, as is generally used. The vulcanizing agent forms a sulfide bond in the carbon-carbon unsaturated bond contained in at least one of the natural rubber compound or the diene synthetic rubber compound (B) in the rubber composition, and improves the strength of the rubber composition. Can be added.

(Vulcanization accelerator)
Next, the vulcanization accelerator will be described.

  A vulcanization accelerator can be added to the rubber composition of the present invention as necessary. When a vulcanization accelerator is added, the vulcanization accelerator increases the vulcanization speed, shortens the vulcanization time, lowers the vulcanization temperature, reduces the vulcanizing agent, or increases the mechanical properties of the vulcanizate. Although it is not particularly limited as long as it can be improved, for example, organic aldehyde ammonias, aldehyde amines, guanidines, thioureas, thiazoles, sulfenamides, thiurams, dithiocarbamates, xanthates can give. Of these, thiazoles and sulfenamides are preferred from the viewpoint of vulcanization accelerating ability for ordinary diene-based highly unsaturated rubbers. On the other hand, for low unsaturated rubbers such as butyl rubber (IIR), thiurams and dithiocarbamates having high vulcanization accelerating ability are preferable.

(Vulcanization accelerator)
Next, the vulcanization acceleration aid will be described.

A vulcanization acceleration aid can be added to the rubber composition of the present invention as necessary. When a vulcanization acceleration aid is added, the vulcanization acceleration aid reacts with the vulcanization accelerator to increase the vulcanization speed, shorten the vulcanization time, lower the vulcanization temperature, Although it will not specifically limit if the weight reduction of an agent and the physical property of a vulcanizate can be improved, For example, a magnesium oxide, zinc oxide (zinc white), a zinc stearate etc. are mentioned.
Among these, zinc stearate is preferable from the viewpoint of improving compatibility with rubber and vulcanization promoting action.
In addition, when stearic acid is included in the blend of the rubber composition, zinc oxide and stearic acid may react to produce zinc stearate during the process of uniformly kneading the rubber composition or vulcanization treatment. . Therefore, when stearic acid is included in the blend of the rubber composition, zinc oxide can also be preferably used.

Furthermore, other additives may be included.
Examples of such additives include silane coupling agents such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, and vinyl silane, titanate coupling agents, aluminum coupling agents, and aluminum / zirconium coupling agents. Various coupling agents, butyl cellosolve, carbitol, butyl cellosolve, carbitol acetate, ethylene glycol diethyl ether, α-terpineol and other diluents with relatively high boiling points, colorants such as Bengala, polyethylene wax, higher fatty acid esters, fatty acids Synthetic waxes such as amides, ketones and amines, hydrogenated oils, paraffin waxes, natural waxes such as montan wax, mold release agents such as paraffin, silicone oils, silico Examples include low stress components such as rubber, antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, zinc molybdate, flame retardants such as phosphazene, and inorganic ion exchangers such as bismuth oxide hydrate. A combination of one or more of these may be used.

  Moreover, when using the said rubber composition for a tire use, you may contain antioxidant. When the natural rubber compound or the diene synthetic rubber compound (B) has an unsaturated bond, the unsaturated bond is prevented from being deteriorated by being subjected to an oxidation reaction or a cleavage reaction due to oxygen, ozone, heat, ultraviolet light, or the like. Used for. Examples of the antioxidant include, but are not limited to, aromatic amine derivatives, phenol derivatives, quinoline derivatives, dithiocarbamates and imidazoles, and phenol derivatives are used from the viewpoint of colorability. It is preferable.

<Hardened product of rubber composition>
Next, the cured product of the rubber composition of the present invention will be described.

  The cured product of the rubber composition can be obtained by heat-treating the rubber composition. When the heat treatment is performed, the temperature is preferably about 100 to 280 ° C, more preferably about 120 to 250 ° C, and further preferably about 130 to 230 ° C.

<Tire>
Next, the tire of the present invention will be described.

The tire can be obtained by molding the rubber composition.
First, the rubber composition is kneaded. At this time, if necessary, a filler (C), a crosslinking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, an antioxidant, and the like may be added.
Next, the kneaded rubber composition is processed into a lump or plate so that it can be easily molded. The processing shape is not particularly limited, but it is preferable to form a plate with a roll from the viewpoint of workability.

Next, the processed rubber composition is extruded into a tread mold and cut to the length of one tire to produce a tread portion.
Further, a tire cord is rubbed into the processed rubber composition and cut into each tire width to produce a carcass belt portion.
Furthermore, a necessary number of bead wires are arranged according to the tire, and the bead wire is covered with rubber by extruding it together with the plate-like molded product, thereby producing a bead portion.
A raw tire is produced by bonding the tread part, the carcass belt part, and the bead part produced as described above to the shape of the mature tire.
The raw tire is put into a mold, and the tire is manufactured by directing the green tire from the inside toward the mold with a compression device. The production method is not particularly limited, but it is preferably pressed with high-temperature and high-pressure steam in order to improve the vulcanization efficiency of the rubber composition. The molding temperature at this time is preferably about 100 to 280 ° C, more preferably about 120 to 250 ° C, and further preferably about 130 to 230 ° C.

<Method for producing rubber composition>
Next, an example of the manufacturing method of the rubber composition of this invention is demonstrated.

  A method for producing a rubber composition and a cured product thereof includes: [1] a step of extracting a lignin derivative (A) from biomass; [2] a compound comprising the extracted lignin derivative (A) and a rubber compound (B). To obtain a rubber composition. Hereinafter, each process will be described sequentially.

[1]
[1-1] The lignin derivative (A) may be prepared by any method. Hereinafter, a method for obtaining the plant-derived lignin derivative (A) by decomposing biomass will be described.

  First, biomass is placed in the presence of a solvent and decomposed under high temperature and pressure. Biomass is a plant or a processed product of a plant as described above. Examples of this plant include broadleaf trees such as beech, birch and oak, conifers such as cedar, pine and cypress, bamboo, rice straw. Such grasses, coconut shells and the like.

  In the decomposition treatment, it is preferable to pulverize the biomass into blocks, chips, powders, or the like. In that case, the size after pulverization is preferably about 100 μm to 1 cm, and more preferably about 200 to 1000 μm. By using biomass of such a size, it is possible to improve the dispersibility of the biomass in the liquid and to efficiently perform the biomass decomposition treatment.

  Examples of the solvent used in the decomposition step include water, alcohols such as methanol and ethanol, phenols such as phenol and cresol, ketones such as acetone and methyl ethyl ketone, dimethyl ether, ethyl methyl ether, diethyl ether, Ethers such as tetrahydrofuran, nitriles such as acetonitrile, amides such as N, N-dimethylformamide, and the like, and one or two or more of them are used as a mixed solvent.

  As the solvent, water is particularly preferably used. As a usage-amount of a solvent, it is so good that it is large with respect to biomass, However, Preferably it is about 1-20 mass times with respect to biomass, and it is more preferable that it is about 2-10 mass times.

  Next, the biomass in the presence of the solvent is decomposed under high temperature and pressure. Thereby, biomass is decomposed | disassembled into lignin, a cellulose, hemicellulose, those decomposition products, another reaction material, etc.

  In the generation of a high temperature and high pressure environment, a pressure vessel such as an autoclave is used. Moreover, as this pressure vessel, what is equipped with a heating means and a stirring means is used preferably, and it is preferable to stir biomass under high temperature and pressure. Moreover, you may provide the means to pressurize independently from the factor which influences pressure, such as the temperature in a container, as needed. Examples of such means include means for introducing an inert gas such as argon gas into the container.

  As for the conditions in the decomposition treatment, the treatment temperature is preferably 150 to 400 ° C, more preferably 180 to 350 ° C, and further preferably 220 to 320 ° C. If processing temperature is in the said range, the molecular weight of the lignin derivative (A) obtained after decomposition | disassembly will become what can make reactivity (curability) and compatibility compatible. In addition, when processing temperature is less than the said lower limit, biomass cannot fully be decomposed | disassembled, there exists a possibility that the molecular weight of a lignin derivative (A) may become higher than needed, and it may be inferior to solubility and a meltability. On the other hand, when processing temperature exceeds the said upper limit, the molecular weight of a lignin derivative (A) becomes low more than necessary, and when using it as a resin raw material, there exists a possibility that reactivity may fall.

  Moreover, it is preferable that the processing time in a decomposition process is 480 minutes or less, and it is more preferable that it is 10 to 360 minutes. If the treatment time is within the above range, the ratio of the integral value of 1H-NMR of the lignin derivative (A) obtained after the decomposition [aliphatic 1H integral value / aromatic 1H integral value] becomes an appropriate value, and compatibility is improved. Can be improved.

  Furthermore, the pressure in the decomposition treatment is preferably 1 to 40 MPa, more preferably 1.5 to 25 MPa, and further preferably 2.5 to 20 MPa. When the pressure is within the above range, the biomass decomposition efficiency can be significantly increased, and the processing time can be shortened accordingly.

  In addition, you may make it add the catalyst which accelerates | stimulates a decomposition process to a solvent as needed. Examples of the catalyst include inorganic bases such as sodium carbonate and oxidizing substances such as hydrogen peroxide. The amount of these catalysts added is preferably about 0.1 to 10% by mass, more preferably about 0.5 to 5% by mass in the concentration in the solvent.

  Furthermore, as a pretreatment for the decomposition step, it is preferable to perform a step of sufficiently stirring the biomass and the solvent and allowing them to blend. Thereby, the decomposition of biomass can be particularly optimized. The stirring temperature is preferably about 0 to 150 ° C, and more preferably about 10 to 130 ° C. Further, the stirring time is preferably about 1 to 120 minutes, more preferably about 5 to 60 minutes. Further, examples of the stirring method include various mills such as a ball mill and a bead mill, a method using a stirrer equipped with a stirring blade, a method using water flow stirring using a homogenizer, a jet pump, and the like.

The solvent used in the decomposition treatment is preferably used in a subcritical or supercritical state (condition). It is considered that the solvent in the subcritical or supercritical state contributes to the acceleration of the biomass decomposition process. For this reason, the efficiency of a decomposition process can be improved more, the reduction of the manufacturing cost of a lignin derivative (A), and the simplification of a manufacturing process can be aimed at.
As an example, the critical temperature of water is about 374 ° C., and the critical pressure is about 22.1 MPa.

[1-2]
Next, the processed product in the pressure vessel is filtered. Then, the filtrate is removed, and the solid component (solvent insoluble matter) separated by filtration is recovered.
In addition, in the said decomposition | disassembly process, when organic solvents other than water are mixed and used, the lignin derivative (A) may be contained in the soluble component separated by filtration. In that case, the organic solvent is distilled off from the soluble component, and the solid component containing the produced lignin derivative (A) is recovered by filtration.

  The solid component collected above is immersed in a solvent in which the lignin derivative (A) is soluble. The solid component in which the lignin derivative (A) is immersed in a solvent is separated into a component soluble in the solvent (soluble component) and a component insoluble in the solvent (insoluble component).

  As the solvent in which the lignin derivative (A) is soluble, for example, those containing alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone are preferably used.

  The immersion time is not particularly limited, but is preferably about 1 to 48 hours, and more preferably about 2 to 30 hours. Moreover, it is also possible to heat at the boiling point or less of a solvent at the time of immersion.

[1-3]
Next, a solvent soluble part is collect | recovered from the processed material obtained by the immersion process. And the solvent in which a lignin derivative (A) is soluble is distilled off from the collect | recovered solvent soluble content. Thereby, a lignin derivative (A) is extracted.

[2]
Next, a compound containing the extracted lignin derivative (A) and the rubber compound (B) is mixed to obtain a rubber composition.

A method for obtaining a rubber composition by mixing a compound containing the extracted lignin derivative (A) and the rubber compound (B) is not particularly limited, but a method for obtaining a rubber composition by heating and kneading. Will be described.
First, a compound containing the extracted lignin derivative (A) and the rubber compound (B) is heated to 100 ° C. and kneaded. At this time, the calorific value at the time of kneading | mixing can be suppressed as the carbon content measured by the elemental analysis method of the said lignin derivative (A) is 40 weight% or more.
Further, when the hydroxyl group equivalent of the lignin derivative (A) is 150 g / eq or more, the calorific value can be further suppressed, and the polystyrene measured by gel permeation chromatography (GPC) analysis of the lignin derivative (A). When the converted number average molecular weight is 200 to 2000, it is possible to achieve both high suppression of heat generation and elongation at break.

  When the filler (C), crosslinking agent, vulcanizing agent, vulcanization accelerator and other additives are included, the lignin derivative (A) and the rubber compound (B) are kneaded together. can do. In addition, when the filler (C) includes a crosslinking agent, a vulcanizing agent, vulcanization acceleration and other additives, the order of kneading is not particularly limited.

  Further, when kneading, an organic solvent may be used as necessary. Examples of the organic solvent include, but are not limited to, methanol, ethanol, propanol, butanol, methyl cellosolve, acetone, methyl ethyl ketone, methyl isobutyl ketone, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl- Examples include 2-pyrrolidone, quinoline, cyclopentanone, m-cresol, chloroform, and the like, and one or a mixture of two or more of these is used. Moreover, the solid content concentration in the rubber composition is not particularly limited, but is, for example, about 60 to 98% by mass, and preferably about 70 to 95% by mass.

<Hardened product of rubber composition and method for producing tire>
Next, a process for obtaining a cured product of a rubber composition and a tire will be described. The cured product and tire of the rubber composition can be obtained by molding the rubber composition. Although it does not specifically limit as a shaping | molding method, The case where it shape | molds using a metal mold | die is demonstrated.
The produced rubber composition is molded using a mold equipped with a hydraulic press to obtain a cured product of the rubber composition.

  The molding temperature is preferably about 100 to 280 ° C, more preferably about 120 to 250 ° C, and still more preferably about 130 to 230 ° C.

Next, specific examples and comparative examples of the present invention will be described, but the present invention is not limited thereto.
1. Production of rubber composition and cured product of rubber composition

Example 1
(1) Extraction of lignin derivative 100 g of cedar wood flour (60 mesh under) and 400 g of a solvent made of pure water were mixed and introduced into a 1 L autoclave. Then, while stirring the contents at 300 rpm, as a pretreatment, the mixture was stirred for 15 minutes at room temperature. After sufficiently blending the cedar wood flour and the solvent, it was treated at 300 ° C. and 10 MPa for 60 minutes to obtain cedar wood flour. Disassembled.
Subsequently, the obtained decomposition product was filtered, and the solid component separated by filtration was recovered.
Subsequently, the obtained solid component was immersed in 200 ml of acetone for 12 hours. This was filtered to recover acetone-soluble components.
Subsequently, acetone was distilled off from the acetone-soluble component and dried to obtain 3.2 g of a lignin derivative (A).

(2) Evaluation of lignin derivative (A) (2) -1 Evaluation of carbon content The lignin derivative (A) obtained by the above method was measured for carbon content. The carbon content was measured by “2400II fully automatic elemental analyzer (CHNS / O) (PerkinElme
r)), the sample was completely burned at 1800 ° C. in pure oxygen, carbon was converted to carbon dioxide, and the amount of carbon dioxide was quantified by frontal chromatography to measure the carbon content contained in the sample. . The measurement results are shown in Table 1.

(2) -2 Evaluation of hydroxyl equivalent The hydroxyl equivalent of the lignin derivative (A) obtained by the above method was measured. The hydroxyl equivalent was determined by the following method. In a stoppered Erlenmeyer flask, 4.0 g of a mixed solution of acetic anhydride / pyridine (1/3 volume ratio) and 1.0 g of a sample were dissolved. After maintaining this solution at 60 ° C. for 3 hours, 1 ml of pure water was added. The solution thus obtained was titrated with a 0.1 mol / L NaOH aqueous solution with pH = 10 as the end point, and the hydroxyl group equivalent was determined from the following formula. The measurement results are shown in Table 1.
Hydroxyl equivalent (g / eq) = 1000 * W / (((TB * f * S / SB)-(T * f)) * N)
The meaning of each symbol in the formula is as follows.
W: Sample weight (g)
TB: Blank titration (ml)
SB: Amount of blank acetic anhydride-pyridine mixture (g)
T: Titration volume with sample (ml)
S: Amount of acetic anhydride-pyridine mixed solution added with sample (g)
f: Factor of standard aqueous sodium hydroxide solution
N: Normality of sodium hydroxide standard aqueous solution

(2) -3 Evaluation of number average molecular weight About the lignin derivative (A) obtained by the said method, the number average molecular weight (Mn) was measured by gel permeation chromatography (GPC). The measurement results are shown in Table 1.

(2) -4 Evaluation of [Aliphatic 1H Integral Value / Aromatic 1H Integral Value] Ratio Using the lignin derivative (A) obtained by the above method, a 1% by weight heavy dimethyl sulfoxide solution was prepared. Next, ¹ H-NMR was measured, and a peak of an aromatic ring was observed at 7 to 8 ppm, a methoxy group at 3.5 to 4 ppm, and an alkyl group at 0.5 to 3 ppm, confirming that it was a lignin resin. The ratio of the integral value of 0.0 to 6.0 ppm excluding the integral value derived from the solvent and the internal standard substance and the integral value of 6.0 to 8.0 ppm [aliphatic 1H integral value / aromatic 1H integral value] Calculated. The calculation results are shown in Table 1.

(3) Preparation of rubber composition 100 parts by weight of the lignin derivative (A) obtained by the above method, 600 parts by weight of a natural rubber compound (RSS 3, manufactured by Tochi), carbon black (Dia Black ISAF, average particle) After blending 400 parts by weight, 20 parts by weight of hexamethylenetetramine, 20 parts by weight of sulfur, 10 parts by weight of zinc oxide, and 15 parts by weight of stearic acid, and kneading at 100 ° C. The cured product of a sheet-like rubber composition having a thickness of 2 mm was obtained by molding at 160 ° C. for 20 minutes.

(4) Evaluation of cured product of rubber composition (4) -1 Evaluation of tan δ The cured product of the rubber composition obtained by the above method was measured for tan δ according to JIS K6394. The measurement is performed using a dynamic viscoelasticity measuring device “ARES (manufactured by TA Instruments)”, and an evaluation index of heat generation due to repeated deformation of the rubber composition under the condition of 16 Hz at 50 ° C. under the condition of 1% dynamic strain. Tan δ was measured. As a result, values of other examples and comparative examples were calculated when the reciprocal of tan δ of comparative example 2 was set to 100. Here, a large value of the reciprocal of tan δ means that the tan δ of the viscoelastic property is small, the thermal energy generated by repeated deformation can be suppressed, and in the case of a tire, fuel efficiency can be improved. It becomes. The measurement results are shown in Table 1.

(4) -2 Evaluation of tensile stress at the time of cutting For the cured product of the rubber composition obtained by the above method, the tensile stress at the time of cutting was measured. The measurement was performed by measuring the tensile stress at the time of cutting using a “Strograph (manufactured by Toyo Seiki)” device under the conditions in accordance with JIS K 6251. The measurement results are shown in Table 1.

(4) -3 Evaluation of elongation at break The elongation at break was measured for the cured product of the rubber composition obtained by the above method. The measurement was performed by measuring the elongation at break using a “Strograph (manufactured by Toyo Seiki)” apparatus under the conditions in accordance with JIS K 6251. The measurement results are shown in Table 1.

(4) -4 Evaluation of storage elastic modulus The storage elastic modulus was measured about the hardened | cured material of the rubber composition obtained by the said method. The measurement was performed using a dynamic viscoelasticity measuring device “ARES (TA Instruments)”, and the storage elastic modulus was measured under the condition of 16% at 50 ° C. under the condition of 1% dynamic strain. The measurement results are shown in Table 1.

(Examples 2 to 13)
The same procedure as in Example 1 was conducted except that the type of biomass, the extraction conditions for the lignin derivative (A), and the composition of the rubber composition were changed as shown in Table 1.

(Example 2)
The procedure was the same as Example 1 except that the treatment time for extracting the lignin derivative was changed to 30 minutes.

(Example 3)
The procedure was the same as Example 1 except that the treatment time for extracting the lignin derivative was changed to 10 minutes.

Example 4
The same procedure as in Example 1 was performed except that the treatment pressure during extraction of the lignin derivative was changed to 9 MPa.

(Example 5)
The biomass during extraction of the lignin derivative was changed to rice straw, the processing pressure was changed to 9 MPa, the processing time was changed to 30 minutes, and the natural rubber compound (RSS 3, manufactured by Tochi) was changed to 300 parts by weight. The same procedure as in Example 1 except that 300 parts by weight of a diene-based synthetic rubber compound (Nipol NS116R, styrene-butadiene rubber, manufactured by Nippon Zeon Co., Ltd.) was added.

(Example 6)
The same procedure as in Example 1 was performed except that the treatment temperature during extraction of the lignin derivative was changed to 220 ° C., the treatment pressure was changed to 3 MPa, and the treatment time was changed to 10 minutes.

(Example 7)
The processing temperature at the time of extraction of the lignin derivative was changed to 220 ° C., the processing pressure was changed to 3 MPa, a natural rubber compound (RSS 3, manufactured by Tochi) was not used, and a diene synthetic rubber compound (Nipol NS116R) was used instead. , Styrene-butadiene rubber, manufactured by Nippon Zeon Co., Ltd.).

(Example 8)
The same procedure as in Example 1 was performed except that the treatment temperature during extraction of the lignin derivative was changed to 250 ° C., the treatment pressure was changed to 4 MPa, and the treatment time was changed to 10 minutes.

Example 9
The procedure was the same as Example 1 except that the amount of the natural rubber compound (RSS 3, manufactured by Tochi) was changed to 1200 parts by weight.

(Example 10)
Example 1 was repeated except that the filler carbon black was changed to silica (Nipsil AQ, manufactured by Tosoh Silica).

(Example 11)
The same procedure as in Example 1 was performed except that the filler carbon black was changed to alumina (Seraph YFA10030 (average particle size 10.0 μm, average thickness 0.30 μm) manufactured by Kinsei Tech).

(Example 12)
The same procedure as in Example 1 was performed except that the cross-linking agent hexamethylenetetramine was changed to hexamethoxymethylmelamine (corresponding to the compound represented by the formula (10) where n is 1).

(Example 13)
Example 1 was repeated except that the lignin derivative was changed to a lignin resin obtained by the following method.
100 g of cedar wood flour (60 mesh under) and 400 g of a mixed solvent composed of 200 g of pure water and 200 g of acetone were mixed and introduced into a 1 L autoclave. Then, while stirring the contents at 300 rpm, as a pretreatment, the mixture was stirred for 15 minutes at room temperature. After sufficiently blending the cedar wood flour and the solvent, it was treated at 300 ° C. and 11 MPa for 60 minutes to obtain cedar wood flour. Disassembled.
Subsequently, the obtained decomposition product was filtered, and the filtrate separated by filtration was recovered.
Next, acetone was distilled off from the obtained filtrate to precipitate a solid component in the aqueous phase. The solid component was filtered, and the solid component was collected and dried to obtain 4.3 g of a lignin derivative (A).

(Comparative Examples 1-6)
The same procedure as in Example 1 was conducted except that the type of biomass, the extraction conditions for the lignin derivative (A), and the composition of the rubber composition were changed as shown in Table 1.

(Comparative Example 1)
The procedure was the same as Example 1 except that no lignin derivative was contained.

(Comparative Example 2)
The procedure was the same as Example 1 except that the lignin derivative was changed to a novolak resin obtained by the following method.
In a three-necked flask equipped with a stirrer, 100 g of phenol and 69 g of 37% formalin aqueous solution were mixed, 1 g of oxalic acid was added as a catalyst, and the mixture was reacted at 100 ° C. for 2 hours. Subsequently, dehydration was performed by atmospheric distillation until the temperature of the reaction mixture reached 130 ° C. Thereafter, in order to remove unreacted phenol, the reaction product was gradually reduced in pressure to 0.9 kPa while being heated until the temperature of the reaction mixture reached 170 ° C., and vacuum distillation was performed to obtain a novolak resin.

(Comparative Example 3)
The procedure was the same as Example 1 except that no rubber compound was contained.

(Comparative Example 4)
The biomass at the time of extraction of the lignin derivative was changed to rice straw, the treatment temperature was changed to 170 ° C., the treatment pressure was changed to 0.8 MPa, and the treatment time was changed to 120 minutes. I made it.

(Comparative Example 5)
The same procedure as in Example 1 was performed except that the biomass during extraction of the lignin derivative was changed to rice straw, the treatment pressure was changed to 20 MPa, and the treatment time was changed to 90 minutes.

(Comparative Example 6)
Example 1 was repeated except that the lignin derivative was changed to a lignin resin obtained by the following method.
10 g of 50 mM M acetate buffer (pH 5) was added to 300 g of cedar wood flour (60 mesh under), and 300 mL of a polysaccharide-degrading enzyme (Genencor, GC220) was added, followed by stirring at 50 ° C. and 150 rpm for 72 hours. After the reaction solution was filtered with a 40 mesh filter cloth, the solid matter remaining on the filter cloth was washed with 10 L of ion exchange water, and the sugar solubilized by the acetate buffer, the polysaccharide degrading enzyme and the enzyme was removed.
From the result of ¹ H-NMR measurement, the obtained solid was found to have an aromatic ring at 7-8 ppm, a methoxy group at 3.5-4 ppm, and an alkyl group peak at 0.5-3 ppm. I confirmed that there was.

  As is apparent from Table 1, the cured product of the rubber composition obtained in each example is excellent in the reciprocal of the tan δ value, which is a measure of low thermal energy generated by repeated deformation, and is a storage, which is a measure of hardness. The elastic modulus was high, and the tensile stress at cutting and the elongation at cutting were high. It was inferred that excellent characteristics were obtained due to the high compatibility between the lignin derivative (A) and the natural rubber compound or the diene synthetic rubber compound (B).

  On the other hand, the comparative examples included those having a low reciprocal of tan δ, a low storage elastic modulus, a low stress at cutting, and a low elongation at cutting.

  The rubber composition of the present invention has low thermal energy generated by repeated deformation, and can be suitably used for applications that require excellent elastic modulus, tensile stress at break and elongation at break, particularly tire applications.

Claims (10)

  A rubber composition containing a lignin derivative (A) and at least one of a natural rubber compound or a diene synthetic rubber compound (B), wherein the lignin derivative (A) is carbon measured by elemental analysis. A rubber composition having a content of 40% by weight or more.   The rubber composition according to claim 1, wherein the lignin derivative (A) has a hydroxyl group equivalent of 150 g / eq or more.   The rubber composition according to claim 1, wherein the lignin derivative (A) is obtained by treating biomass with subcritical water.   The said lignin derivative (A) contains what has the number average molecular weight of polystyrene conversion 200-2000 measured by the gel permeation chromatography (GPC) analysis. Rubber composition.   The lignin derivative (A) has an integral value of 0.0 to 6.0 ppm excluding the integral value derived from the solvent and the internal standard substance when a 1% by weight heavy dimethyl sulfoxide solution is measured by 1H-NMR, The rubber composition according to any one of claims 1 to 4, wherein the ratio [aliphatic 1H integral value / aromatic 1H integral value] of 1.0 to 8.0 ppm is 1.0 to 10.0. object.   The rubber composition according to any one of claims 1 to 5, wherein the content of at least one of the natural rubber or the diene synthetic rubber (B) is 100 to 10,000 parts by weight with respect to 100 parts by weight of the lignin derivative (A). .   The rubber composition according to any one of claims 1 to 6, further comprising a filler (C).   The rubber composition according to claim 7, wherein the filler (C) contains one or more selected from the group consisting of carbon black, silica, and alumina.   A cured product obtained by curing the rubber composition according to claim 1.   A tire obtained by molding the rubber composition according to any one of claims 1 to 8.