JP6687324B2 - Modified conjugated diene polymer and rubber composition containing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a modified conjugated diene polymer capable of improving low heat build-up and abrasion resistance, and a rubber composition containing the same.

Recently, tires with low rolling resistance have been demanded from the viewpoint of energy saving. Therefore, as a rubber composition used for a tire tread or the like, a rubber composition having a low tan δ and an excellent low heat build-up is required. Further, a rubber composition for a tread is required to have excellent wear resistance in addition to low heat buildup. On the other hand, in order to improve the low heat build-up and wear resistance of the rubber composition, various attempts have been made to improve the affinity between the rubber component and the filler such as carbon black or silica in the rubber composition. Has been done.
For example, in Patent Document 1, a polar group-containing compound is graft-polymerized by applying a mechanical shearing force to at least one natural rubber raw material selected from the group consisting of natural rubber, natural rubber latex coagulum and natural rubber cup lamp. Alternatively, a modified natural rubber obtained by adding it has been proposed.
Further, Patent Document 2 discloses a modified natural rubber latex in which a polar group-containing mercapto compound is added to natural rubber latex and the polar group-containing mercapto compound is added to natural rubber molecules in the natural rubber latex.
Further, Patent Documents 3 to 6 propose modified natural rubbers obtained by graft-polymerizing various polar group-containing monomers onto natural rubber latex.
However, in order to further improve the affinity with the reinforcing filler composed of carbon black and / or silica, and to further improve the low heat build-up and abrasion resistance of the rubber composition, a modified conjugated diene-based heavy-weight compound is used. There was room to improve the coalescence further.

JP, 2006-152171, A JP, 2006-152045, A JP, 2004-359716, A JP, 2004-359717, A JP, 2004-359713, A JP, 2004-359714, A

  Under such circumstances, it is an object of the present invention to provide a modified conjugated diene polymer capable of further improving the low heat buildup property and abrasion resistance of the rubber composition, and a rubber composition using the same. It is a thing.

The present inventors have attempted to modify the conjugated diene-based polymer with various compounds in order to solve the above problems, and found that by modifying with a specific compound, the problems of the present invention can be solved. As a result, the present invention has been completed.
That is, the present invention provides a modified conjugated diene-based polymer in which a compound having an amino group and a carboxyl group is covalently bonded to at least one of the terminal, main chain and side chain of the conjugated diene-based polymer, and the modified conjugated diene. A rubber composition containing a polymer.

  According to the present invention, it is possible to provide a modified conjugated diene polymer capable of further improving the low heat build-up property and abrasion resistance of the rubber composition, and a rubber composition using the same.

[Modified conjugated diene polymer]
The present invention is a modified conjugated diene-based polymer in which a compound having an amino group and a carboxyl group is covalently bonded to at least one of the terminal, main chain and side chain of the conjugated diene-based polymer, wherein the amino group And a compound having a carboxyl group is at least one compound selected from the group consisting of tyrosine and tyrosine peptides, which is a modified conjugated diene polymer.
The conjugated diene-based polymer used in the modified conjugated diene-based polymer of the present invention is preferably a polymer (polymer) containing no non-conjugated olefin as a monomer unit component (a part of the copolymer). Note that styrene and acrylonitrile are not included in the non-conjugated olefin.
The conjugated diene-based polymer is not particularly limited and may be either a diene-based homopolymer or a diene-based copolymer, which can be appropriately selected according to the purpose. Examples thereof include natural rubber (NR) and various types. Polybutadiene rubber (BR), synthetic polyisoprene rubber (IR), various styrene-butadiene copolymer rubber (SBR), styrene-isoprene copolymer rubber (SIR), styrene-isoprene-butadiene terpolymer rubber, isoprene -Butadiene copolymer rubber (IBR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber, etc. are mentioned. Among these, natural rubber and emulsion-polymerized styrene-butadiene copolymer rubber are preferable, and natural rubber is particularly preferable.

[Compound Having Amino Group and Carboxyl Group]
The compound having an amino group and a carboxyl group according to the present invention is not particularly limited, but is preferably at least one selected from the group consisting of amino acids, peptides, polyamino acids and proteins.
The compound having an amino group and a carboxyl group according to the present invention, at least one compound selected from peptides or Ranaru groups tyrosine and tyrosine are exemplified particularly suitably.

In the compound having an amino group and a carboxyl group according to the present invention, the peptide means a plurality of amino acids linked by an amide bond. The polyamino acid refers to a polymer composed of repeating units of a plurality of amino acids (including, for example, one polymerized with a side chain carboxyl group and an amine group), and is also called a polypeptide.
The number of amino acid residues means the number of amino acid residues contained in a protein, polyamino acid or peptide (including the terminal), and in the present invention, the number of amino acid residues is represented by AA. That is, 2AA represents 2 amino acid residues. The average number of amino acid residues refers to the arithmetic mean value of the number of amino acid residues.
When the compound having an amino group and a carboxyl group according to the present invention is a peptide, it is preferable that the number of amino acid residues is 2 (2AA) or more and the number of amino acid residues is 130 (130AA) or less, and the number of amino acid residues is 2 (2AA). ) It is more preferable that the number of amino acid residues is 100 (100AA) or less, and it is further preferable that the number of amino acid residues is 2 (2AA) or more and 10 (10AA) or less. If it is 2 AA or more, that is, in the case of a peptide, the amino group and the carboxyl group are slightly separated from the polymer, so that the influence of steric hindrance is suppressed and the interaction with the filler is easy. Also, because the number of side chains increases, there is a possibility that it may interact with the filler, and if it is 130 AA or less, the increase in polymer gel can be suppressed while the interaction with the filler is enhanced. is there.
The number of amino acid residues of amino acids such as tyrosine and cystine is 1 (1AA). The amino acid of 1AA is preferable because it has a high effect of improving the low heat buildup and abrasion resistance of the rubber composition.
Therefore, the average number of amino acid residues (AA) of the compound having an amino group and a carboxyl group according to the present invention is preferably 1 or more and 130 or less, more preferably 1 or more and 100 or less, and 1 or more and 10 or less. Is more preferable.

In the present invention, the average number of amino acid residues (AA) is measured by the following method.
After removing non-covalently bound proteins and peptides by reprecipitation of the modified conjugated diene polymer sample, the infrared absorption spectrum was measured by infrared spectroscopy, and the amide bond of the modified conjugated diene polymer was measured. The peculiar absorption wavelength is quantified, and the amide bond amount (mmol) in 100 g of the test sample of the modified conjugated diene polymer is calculated.
Next, the total amount of amino acids is obtained by the following equation (a), and the average number of amino acid residues (AA) of the binding peptide is obtained by the following equation (b). The definition of the modification degree and the measuring method will be described later.
Degree of modification + amide bond amount = total amino acid amount (mmol) (a)
(Total amino acid amount / denaturation degree) = average number of amino acid residues (AA) (b)
The amino acid in the compound having an amino group and a carboxyl group according to the present invention may be other than 20 kinds existing in the living body.

In the present invention, the degree of modification (mmol) means the amount of bonding [mmol (mmol)] of the compound having the amino group and the carboxyl group in 100 g of the modified conjugated diene polymer. In the present invention, the amount of the compound having an amino group and a carboxyl group in 100 g of the modified conjugated diene polymer is preferably 0.005 to 55 mmol, more preferably 0.01 to 27 mmol, and 0 More preferably, it is 0.05 to 16 mmol.
In the case of natural rubber, if the degree of modification is too high, the elongation crystallinity may be adversely affected. Therefore, the degree of modification of 2.0 mmol or less is particularly desirable in order to be compatible with the low loss property.
The modification degree is measured by the following method.
The test sample of the modified conjugated diene polymer was immersed in 6N hydrochloric acid at 110 ° C. for 24 hours to cause a hydrolysis reaction and reprecipitation to remove non-covalently bound amino acids and peptides, followed by pyrolysis gas chromatography ( The amount of amino acid (mmol) in 100 g of the test sample of the modified conjugated diene-based polymer is quantified by pyrolysis GC) to obtain the modification degree (mmol).
The peptide can be prepared by cleaving the protein contained in the latex with protease or the like.

The compound having an amino group and a carboxyl group according to the present invention is reacted with the molecular chain terminal of the conjugated diene-based polymer, and / or the double bond in the molecular chain or the α-position of the double bond to modify the compound of the present invention. A conjugated diene polymer is formed.
Among the compounds having an amino group and a carboxyl group according to the present invention, the modified conjugated diene polymer of the present invention includes tyrosine, a peptide containing tyrosine (which may contain tyrosine at the end), and a polyamino acid containing tyrosine ( May contain tyrosine at the end.), The phenoxy group of the compound becomes a phenoxy radical by a phenol oxidase such as laccase, and the radical is a conjugated diene. It is preferably formed by addition to the terminal of the system polymer and / or addition to the double bond in the molecular chain (at least one of the main chain and the side chain) or the α-position of the double bond.
The phenol oxidase is preferably laccase. Laccase is an oxidase that has the ability to oxidize phenols.
Further, the compound having an amino group and a carboxyl group according to the present invention comprises cystine, a peptide containing cystine (which may contain cystine at the terminal), and a polyamino acid containing cystine (which may contain cystine at the terminal). In the case of at least one compound selected from the group, the reactivity of the thiol group is high, so that even without a reaction catalyst, the end of the conjugated diene polymer and / or the intramolecular chain (main chain and side chain) can be used. Reacts readily with double bonds on at least one of the chains). However, for the purpose of accelerating the reaction, a radical polymerization initiator such as 2,2′-azodiisobutyronitrile (AIBN) or peroxide may be added if desired.

  The modified conjugated diene polymer of the present invention preferably has a small amount of polymer gel. Here, the polymer gel means a component in the polymer in which the polymer molecules in the polymer have a high molecular weight by forming a three-dimensional network structure due to cross-linking, etc. Refers to ingredients. If a large amount of polymer gel is present in the modified conjugated diene-based polymer, the processability of the rubber composition containing the modified conjugated diene-based polymer is deteriorated. Therefore, it is preferable that the amount of polymer gel is small. From this viewpoint, the amount of polymer gel in the modified conjugated diene polymer is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 12% by mass or less. The amount of polymer gel was obtained by swelling 0.2 g of rubber in toluene overnight, treating it with a centrifuge at 35,000 rpm for 1.5 hours, allowing the precipitated gel to stand in a fume hood for 2 days, drying and weighing it. As a gel, the value divided by the total mass of the rubber before treatment is expressed in mass%.

The modified conjugated diene-based polymer of the present invention is produced, for example, as follows.
In the present invention, generally, at least one conjugated diene polymer selected from natural rubber and synthetic conjugated diene polymers is added to a latex, a water emulsified product or an aqueous dispersion, and water and, if necessary, an emulsifier. In the solution, the compound having the amino group and the carboxyl group is added, and by stirring at a predetermined temperature, the compound having the amino group and the carboxyl group is a latex of a conjugated diene polymer, a water-emulsified product or water. An addition reaction is carried out at the terminal of the conjugated diene polymer molecule in the dispersion and / or at the double bond in the molecular chain (at least one of the main chain and the side chain). Incidentally, in the addition of the compound having the amino group and the carboxyl group to the latex of the conjugated diene polymer, the water emulsion or the water dispersion, the latex of the conjugated diene polymer, the water emulsion or the water in advance. If desired, an emulsifier may be added to the dispersion, or a compound having an amino group and a carboxyl group may be emulsified with an emulsifier and then added to a latex, a water-emulsion, or a water dispersion of a conjugated diene polymer. If necessary, a reaction catalyst such as laccase, AIBN or organic peroxide can be further added. Incidentally, the latex of the conjugated diene polymer, an emulsifier in water or an aqueous dispersion and / or an emulsifier that can be used for emulsifying the compound having an amino group and a carboxyl group is not particularly limited, such as polyoxyethylene lauryl ether. Nonionic surfactants are mentioned.

  In order to improve the low heat build-up and abrasion resistance of the rubber composition by reducing the processability of the rubber composition by adding a filler such as carbon black or silica to the modified conjugated diene-based polymer of the present invention, each conjugated diene Since it is important that the compound having the amino group and the carboxyl group are introduced into the polymer molecule in a small amount and uniformly, the modification reaction is preferably carried out while stirring. For example, the conjugated diene polymer A conjugated diene polymer is prepared by charging the above components such as a latex, a water emulsified product or a water dispersion, and a compound having an amino group and a carboxyl group into a reaction vessel and reacting at 30 to 80 ° C. for 10 minutes to 24 hours. A latex, a water emulsified product or a water dispersion of a modified conjugated diene polymer in which the compound having the amino group and the carboxyl group is added to the molecule is obtained. The modified conjugated diene polymer latex, water emulsified product or water dispersion thus obtained may be used as it is in the state of latex, water emulsified product or water dispersion, and further coagulation and drying. You may make it a solid state by doing and use it. When used in a rubber composition, it is preferably used as a solid rubber. When used as a solid rubber, the modified conjugated diene polymer latex, a water-emulsified product or a water dispersion is coagulated and washed, and then dried with a vacuum dryer, an air dryer, a drum dryer, a twin-screw extruder, or the like. A modified conjugated diene polymer in a solid state is obtained by drying using a machine. Here, the latex of the modified conjugated diene-based polymer, the coagulant used for coagulating the water-emulsified product or the water dispersion, is not particularly limited, formic acid, acids such as sulfuric acid, sodium chloride And the like.

  When the addition amount of the compound having an amino group and a carboxyl group in the modified conjugated diene-based polymer of the present invention is 0.01 parts by mass or more, the low heat buildup property and abrasion resistance of the rubber composition are particularly preferably improved. be able to. When the addition amount of the compound having an amino group and a carboxyl group is 10 parts by mass or less, the physical properties inherent to the conjugated diene polymer such as viscoelasticity and SS characteristics (stress-strain curve in a tensile tester) are increased. It is possible to ensure the excellent physical properties inherent to the conjugated diene polymer without any change and to maintain or improve the processability of the rubber composition particularly suitably.

  The rubber component of the rubber composition according to the present invention may contain other diene rubber in addition to the above modified conjugated diene polymer within a range not departing from the object of the present invention. For example, in the rubber component, the modified conjugated diene polymer is preferably 50 to 100% by mass and the other diene rubber is 50 to 0% by mass. Other diene rubbers include natural rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, polyisoprene rubber, acrylonitrile-butadiene copolymer rubber, butyl rubber, halogenated butyl rubber (Cl-IIR, Br-IIR, etc.), Ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-butadiene copolymer rubber (EBR), propylene-butadiene copolymer rubber (PBR), chloroprene rubber and the like can be used. The modified conjugated diene polymer may be used alone or as a blend of two or more kinds, and other diene rubbers may be used as a single kind or as a blend of two or more kinds.

  The rubber composition according to the present invention preferably further contains a filler in addition to the rubber component containing the modified conjugated diene polymer. Here, the blending amount of the filler is not particularly limited, but is preferably in the range of 5 to 150 parts by mass, and 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component containing the modified conjugated diene polymer. The range of parts is more preferable. When the compounding amount of the filler is 5 parts by mass or more, the reinforcing property can be suitably obtained, and when the compounding amount is 150 parts by mass or less, deterioration of workability can be prevented.

As the filler mixed in the rubber composition according to the present invention, at least one selected from carbon black and an inorganic filler is used.
The carbon black is not particularly limited and includes, for example, high, medium or low structure SAF, ISAF, IISAF, N339, HAF, FEF, GPF, SRF grade carbon black, particularly SAF, ISAF, IISAF, N339, HAF, FEF. It is preferred to use a grade of carbon black. The nitrogen adsorption specific surface area (N ₂ SA, measured according to JIS K 6217-2: 2001) is preferably 30 to 250 m ² / g.
This carbon black may be used alone or in combination of two or more. In the present invention, carbon black is not included in the inorganic filler.

As the inorganic filler to be added to the rubber composition according to the present invention, silica is preferable from the viewpoint of achieving both low heat buildup and abrasion resistance. As the silica, any commercially available silica can be used. Among them, wet precipitation method (precipitation method) silica, wet gelation method silica, dry silica and colloidal silica are preferably used, and wet precipitation method silica is particularly preferable. The BET specific surface area (measured in accordance with ISO 5794/1) of silica is preferably 40 to 350 m ² / g. Silica having a BET surface area within this range is advantageous in that it can achieve both rubber-reinforcing properties and dispersibility in rubber components. In this respect, BET surface area is more preferably silica in the range of 80~350m ² / g, silica BET surface area in the range of 120~350m ² / g is particularly preferred. Examples of such silica include Tosoh Silica Co., Ltd., trade name "Nipsil AQ" (BET specific surface area = 205 m ² / g), "Nipsil KQ", and Degussa Co. trade name "Ultrasil VN3" (BET specific surface area = Commercially available products such as 175 m ² / g) can be used.

As the inorganic filler compounded in the rubber composition according to the present invention, an inorganic compound represented by the following general formula (3) can be used in addition to silica or in addition to silica.
dM ¹ · xSiO _y · zH ₂ O (3)
Here, in the general formula (3), M ¹ is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium, and zirconium, an oxide or hydroxide of these metals, and a hydrate thereof. Or at least one selected from carbonates of these metals, and d, x, y, and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10. is there.
In the general formula (3), when both x and z are 0, the inorganic compound is at least one metal, metal oxide or metal hydroxide selected from aluminum, magnesium, titanium, calcium and zirconium. Becomes
Further, it is preferable that M ¹ in the general formula (3) is at least one selected from aluminum metal, aluminum oxides or hydroxides, hydrates thereof, and aluminum carbonates. Aluminum oxide [Al (OH) ₃ ] is particularly preferred.
The inorganic filler in the present invention may be silica alone or may be used in combination with silica and one or more kinds of inorganic compounds represented by the general formula (3).

In the rubber composition according to the present invention, various compounding agents such as stearic acid, a resin acid, a vulcanization activator such as zinc white, a vulcanization accelerator, an antiaging agent, and a softening agent, which are usually compounded in the rubber composition, If necessary, the kneading is carried out in the first stage or the final stage of the kneading, or in the intermediate stage between the first stage and the final stage.
As the kneading device in the present invention, a Banbury mixer, an intermeshing type internal mixer, a roll, an intensive mixer, a kneader, a twin-screw extruder or the like is used.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
The amount of addition, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index) and the abrasion resistance (index) were evaluated by the following methods.

1. Addition amount The addition amount is the binding amount (parts by mass) of the compound containing an amino group and a carboxyl group bonded to 100 parts by mass of the modified conjugated diene polymer. The test sample of the modified conjugated diene-based polymer was immersed in 6N hydrochloric acid at 110 ° C. for 24 hours to cause a hydrolysis reaction and reprecipitation to remove non-covalently bound amino acids and peptides, followed by pyrolysis gas chromatography (GC The amount of amino acid (parts by mass) in 100 parts by mass of the test sample of the modified conjugated diene polymer was quantified by the method (1) to be used as the added amount.
2. Degree of modification The degree of modification is the amount of binding [mmol (mmol)] of the compound containing an amino group and a carboxyl group in 100 g of the modified conjugated diene polymer. The test sample of the modified conjugated diene-based polymer was immersed in 6N hydrochloric acid at 110 ° C. for 24 hours to cause a hydrolysis reaction and reprecipitation to remove non-covalently bound amino acids and peptides, followed by pyrolysis gas chromatography (GC The amount of amino acid (mmol) in 100 g of the test sample of the modified conjugated diene-based polymer was quantified by the method (1) to determine the degree of modification (mmol).
3. Average number of amino acid residues (AA)
After removing non-covalently bound proteins and peptides by reprecipitation of the modified conjugated diene polymer sample, the infrared absorption spectrum was measured by infrared spectroscopy, and the amide bond of the modified conjugated diene polymer was measured. The characteristic absorption wavelength was quantified, and the amide bond amount (mmol) in 100 g of the test sample of the modified conjugated diene polymer was calculated.
Next, the total amount of amino acids was calculated by the following formula (a), and the average number of amino acid residues (AA) of the binding peptide was calculated by the following formula (b).
Degree of modification + amide bond amount = total amino acid amount (mmol) (a)
(Total amino acid amount / denaturation degree) = average number of amino acid residues (AA) (b)
4. Polymer gel amount 0.2 g of rubber was swollen in toluene overnight, treated with a centrifuge at 35000 rpm for 1.5 hours, and the precipitated gel was left to stand in a fume hood for 2 days to be dried and weighed to obtain a polymer gel. The value obtained by dividing by the total mass of the rubber before treatment was expressed in mass%.

5. Low fever (tan δ index)
Using a spectrometer (dynamic viscoelasticity measurement tester) manufactured by Ueshima Seisakusho, frequency (52 Hz), initial strain 10%, measurement temperature 60 ° C., dynamic strain 1% (E ″ / E ′) = tan δ was measured and vulcanized. In the rubber compositions 1 and 2, the tan δ of the vulcanized rubber composition 1 of Comparative Example 1 was set to 100, or the tan δ of the vulcanized rubber composition 3 of Comparative Example 3 was set to 100, and the values were indexed by the following formula. The smaller is the lower exothermicity, and the smaller is the hysteresis loss.
Low exothermic index = {(tan δ of vulcanized rubber composition under test) / (tan δ of vulcanized rubber composition 1 of Comparative Example 1 or tan δ of vulcanized rubber composition 3 of Comparative Example 3)} × 100

6. Abrasion resistance (index)
According to JIS K 6264-2: 2005, using a Lambourn type abrasion tester, a test was performed at room temperature under a condition of a slip ratio of 25%, and the reciprocal of the abrasion amount of the vulcanized rubber composition 1 was compared with that of Comparative Example 1. The tan δ was set to 100, the tan δ of Comparative Example 1 was set to 100 in the vulcanized rubber composition 2, or the tan δ of Comparative Example 3 was set to 100 in the vulcanized rubber composition 3, and the tan δ was expressed by the following formula. The larger the value, the better the wear resistance.
Abrasion resistance index = {(amount of wear of vulcanized rubber composition of Comparative Example 1 or 3) / (amount of wear of vulcanized rubber composition under test)} × 100

Production example 1
(Natural rubber latex modification reaction process)
Water was added to the natural rubber field latex to obtain a latex having a dry rubber concentration of 30% by mass. 2000 g of this latex was put into a stainless steel reaction container equipped with a stirrer and a temperature control jacket, and 10.8 g of tyrosine (1.8 parts by mass relative to 100 parts by mass of natural rubber component) and laccase (manufactured by Novozymes, product A modified natural rubber latex was obtained by adding 0.6 g of "NS81268") and emulsifying the mixture and reacting the mixture at 50 ° C for 1 hour while stirring.

(Coagulation and drying process)
Next, formic acid was added to the modified natural rubber latex to adjust the pH to 4.7 to coagulate the modified natural rubber latex. The solid thus obtained was treated 5 times with a creper, passed through a shredder to be crumbed, and then dried at 110 ° C. for 210 minutes by a hot air dryer to obtain a modified conjugated diene polymer which is a modified natural rubber. I got A. The amount of tyrosine added, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index), and the abrasion resistance (index) in the obtained modified conjugated diene polymer A were evaluated by the above methods. The results are shown in Tables 1 and 3. The average number of amino acid residues (AA) of tyrosine is 1.

Production example 2
(Natural rubber latex modification reaction process)
2000 g of field latex adjusted to have a dry rubber concentration of 30% by mass was charged into a stainless reaction vessel equipped with a stirrer and a temperature control jacket, and 7.2 g (1.2 parts by mass) of cystine was added, and these were replaced with nitrogen. While stirring at room temperature for 30 minutes.
Next, 2.4 g of tert-butyl hydroperoxide and 2.4 g of tetraethylenepentamine were added as polymerization initiators and reacted at 40 ° C. for 1 hour to obtain a modified natural rubber latex.
(Coagulation and drying process)
Then, a modified conjugated diene polymer B, which is a modified natural rubber, was obtained through the coagulation and drying steps in the same manner as in Production Example 1. The amount of cystine added, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index) and the abrasion resistance (index) in the obtained modified conjugated diene polymer B were evaluated by the above methods. The results are shown in Tables 1 and 3. The average number of amino acid residues (AA) in cystine is 1.

Production Examples 3, 5, 7 and 10
As the compound having an amino group and a carboxyl group, 10.8 g (1.8 parts by mass) of tyrosine was added as the compound having an amino group and a carboxyl group shown in Table 1, except that the amounts shown in Table 1 were added. Modified conjugated diene-based polymers C, E, G and K were obtained in the same manner as in 1. Addition amount, modification degree, polymer gel amount, low heat buildup (tan δ index) and abrasion resistance (index) of the compound having an amino group and a carboxyl group in the obtained modified conjugated diene polymer C, E, G and K. Was evaluated by the above method. The results are shown in Tables 1 and 3. Table 1 shows the average number of amino acid residues (AA) of each compound having an amino group and a carboxyl group.

Production Examples 4 and 6
The above Production Example except that the amount of the compound having an amino group and a carboxyl group shown in Table 1 is added in place of 1.2 g (1.2 parts by mass) of cystine as the compound having an amino group and a carboxyl group. In the same manner as in 2, modified conjugated diene polymers D and F were obtained. In the obtained modified conjugated diene polymers D and F, the addition amount of the compound having an amino group and a carboxyl group, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index) and the abrasion resistance (index) were determined by the above-mentioned method. It was evaluated by. The results are shown in Tables 1 and 3. Table 1 shows the average number of amino acid residues (AA) of each compound having an amino group and a carboxyl group.

Production Examples 8, 9 and 10
First, the natural rubber latex was centrifuged to recover the serum phase, and the pH of the serum phase was adjusted to 4.7 to prepare a reaction solution A.
Next, the dried natural rubber cup lamp having a weight of 600 g was cut into 1 mm square pieces and immersed in the reaction solution A (1500 ml). Further, in Production Example 8, 21.6 g (3.6 parts by mass) of tyrosine and 0.6 g of laccase (manufactured by Novozymes, trade name “NS81268”) were added and reacted for 1 hour while stirring. In Production Example 9, 24.0 g (4.0 parts by mass) of a peptide (10AA) having a tyrosine at the terminal (random synthesis) and 0.6 g of laccase (manufactured by Novozymes, trade name “NS81268”) were added, and 1 Reacted for hours. The obtained modified natural rubber was subjected to a drying step in the same manner as in Production Example 1 to obtain modified conjugated diene polymers H and J which are modified natural rubbers. In Production Example 10, 24.0 g (4.0 parts by mass) of Trpsin inhibitor 20.1 kDa was added in place of 24.0 g (4.0 parts by mass) of the peptide (10AA) having tyrosine at the end (random synthesis). A modified conjugated diene polymer K was obtained in the same manner as in Production Example 9 except for the above. The modified conjugated diene polymers H, J, and K thus obtained have the addition amount of the compound having an amino group and a carboxyl group, the degree of modification, the amount of polymer gel, low heat buildup (tan δ index), and abrasion resistance (index). Was evaluated by the above method. The results are shown in Tables 1 and 3. Table 1 shows the average number of amino acid residues (AA) of each compound having an amino group and a carboxyl group.

Production Example 11
The above-mentioned natural rubber latex was directly coagulated and dried without going through a modification reaction step to prepare an unmodified conjugated diene polymer L, which was used as an unmodified conjugated diene polymer L. The amount of polymer gel, low heat buildup (tan δ index) and abrasion resistance (index) in the unmodified conjugated diene polymer L were evaluated by the above methods. The results are shown in Tables 1 and 3.
Production Example 12
In Indonesia, SIR20, which is a standard block-shaped natural rubber, was used as the unmodified conjugated diene polymer M to obtain the unmodified conjugated diene polymer M. The amount of polymer gel, low heat buildup (tan δ index) and abrasion resistance (index) in the unmodified conjugated diene polymer M were evaluated by the above methods. The results are shown in Tables 1 and 3.

Production Examples 13 and 14
A lump of solution-polymerized SBR (manufactured by LANXESS, trade name “Buna VSL 5025-0 HM” (registered trademark), bound styrene content 25 mass%, 1,2-bond butadiene content 50 mass%) having a weight of 600 g after drying was prepared. It was cut into 1 mm square pieces and immersed in water (1500 ml). Furthermore, in Production Example 13, 30.0 g (5.0 parts by mass) of tyrosine and 0.6 g of laccase (manufactured by Novozymes, trade name “NS81268”) were added and reacted for 3 hours with stirring. In Production Example 14, 48.0 g (8.0 parts by mass) of a peptide (10AA) having tyrosine at the end (random synthesis) and 0.6 g of laccase (manufactured by Novozymes, trade name "NS81268") were added, and the mixture was mixed with stirring 3 Reacted for hours. The modified natural rubber thus obtained was dried at 70 ° C. under reduced pressure to obtain modified conjugated diene-based polymers N and O which are modified natural rubbers. The modified conjugated diene-based polymers N and O thus obtained were subjected to the above-mentioned method for determining the addition amount of the compound having an amino group and a carboxyl group, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index) and the abrasion resistance (index). It was evaluated by. The results are shown in Tables 1 and 3. Table 1 shows the average number of amino acid residues (AA) of each compound having an amino group and a carboxyl group.

Production Examples 15 and 16
In Production Example 15, 25 g (5.0 parts by mass) of cysteine and 1 g of dilauroyl peroxide, and in Production Example 16, 40 g (8.0 parts by mass) of peptide (10AA) having cystine at the end (random synthesis) and di 1 g of lauroyl peroxide was added to a solution SBR in 4 L cyclohexane [manufactured by LANXESS, trade name "Buna VSL (registered trademark) 5025-0 HM", bound styrene content 25% by mass, 1,2-bond butadiene content 50% by mass]. Add to 500 g of solution at 80 ° C. The mixture was then stirred at 80 ° C. for 6 hours. Next, 2.5 g of a stabilizer [manufactured by LANXESS, trade name "Vulkanox (registered trademark) 4020"] was added, and the solvent was distilled off with steam. It was dried at 70 ° C. under reduced pressure to obtain modified conjugated diene polymers P and Q which are modified natural rubber. In the obtained modified conjugated diene polymers P and Q, the addition amount of the compound having an amino group and a carboxyl group, the degree of modification, the amount of polymer gel, the low heat buildup (tan δ index) and the abrasion resistance (index) were determined by the above-mentioned method. It was evaluated by. The results are shown in Tables 1 and 3. Table 1 shows the average number of amino acid residues (AA) of each compound having an amino group and a carboxyl group.

Production Example 17
Solution SBR [manufactured by LANXESS, trade name "Buna VSL (registered trademark) 5025-0 HM", bound styrene content 25 mass%, 1,2-bond butadiene content 50 mass%] was used without denaturation. The conjugated diene polymer R was used. The amount of polymer gel, low heat buildup (tan δ index) and abrasion resistance (index) in the unmodified conjugated diene polymer R were evaluated by the above methods. The results are shown in Tables 1 and 3.

{note}
The addition amount is the addition amount (parts by mass) of the compound having an amino group and a carboxyl group with respect to 100 parts by mass of the conjugated diene polymer.
Moreover, the addition amount is the binding amount (parts by mass) of the compound having an amino group and a carboxyl group bonded to 100 parts by mass of the conjugated diene polymer.
* 1: L-tyrosine, manufactured by Tokyo Kasei Kogyo Co., Ltd. * 2: L-cystine, manufactured by Wako Pure Chemical Industries, Ltd. * 4: Peptide having a cystine at the terminal (10AA) (random synthesis), manufactured by Sigma-Aldrich * 5 : Peptide having tyrosine at the end (20AA) (random synthesis), manufactured by Sigma-Aldrich * 6: Peptide having cystine at the end (20AA) (random synthesis), manufactured by Sigma-Aldrich * 7: Ribonuclease A, 124AA, Jun Wako Yaku Kogyo Co., Ltd. * 8: Trpsin inhibitor, 181AA, Wako Pure Chemical Industries, Ltd.

Example 1 and Comparative Examples 1-2
Six types of rubber compositions of Example 1 and Comparative Examples 1 and 2 were prepared by kneading the rubber compositions 1 and 2 having the compounding contents shown in Table 2 with a Banbury mixer which is a closed kneader. These 6 types of rubber compositions were vulcanized at 145 ° C. for 40 minutes, and then evaluated for low heat buildup (tan δ index) and abrasion resistance (index). The results are shown in Table 3.
Examples 2 to 7, Reference Examples 1 to 7 and Comparative Example 3
Twenty-three kinds of rubber compositions of Examples 2 to 7, Reference Examples 1 to 7 and Comparative Example 3 were obtained by kneading the rubber compositions 1, 2 and 3 having the compounding contents shown in Table 2 with a Banbury mixer which is a closed kneader. To prepare. After vulcanizing these 23 kinds of rubber compositions under conditions of 145 ° C. and 40 minutes, low exothermic property (tan δ index) and abrasion resistance (index) are evaluated. The results are shown in Table 3.

[note]
* 11: Modified conjugated diene-based polymers AK prepared in Production Examples 1 to 10 and unmodified conjugated diene-based polymers L and M described in Production Examples 11 and 12.
* 12: Modified conjugated diene-based polymers NQ prepared in Production Examples 13 to 16 and unmodified conjugated diene-based polymer R described in Production Example 17
* 13: Product name "BR01" manufactured by JSR Corporation
* 14: N339, manufactured by Tokai Carbon Co., Ltd., product name "SEAST KH"
* 15: Tosoh Silica Co., Ltd., wet precipitation silica, trade name "Nipsil AQ"

* 16: Bis (3-triethoxysilylpropyl) disulfide (average sulfur chain length: 2.35), silane coupling agent manufactured by Evonik, trade name "Si75" (registered trademark) * 17: Sankyo Yuka Kogyo Co., Ltd. Process oil made, product name "A / O mix"
* 18: Rheinchemie anti-ozonant wax, trade name "Antiluux (registered trademark) 654"
* 19: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C"
* 20: N, N-dicyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "NOXCELLER DZ"
* 21: N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "NOXCELLER CZ"
* 22: 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sunceller D"
* 23: Di-2-benzothiazolyl disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sunceller DM"
* 24: N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "SANCELLER NS"

As is clear from Table 3, the rubber compositions of Examples 1 to 5 are carbon black compounded rubber compositions, rubber composition 1 and silica compounded rubber, as compared with the rubber compositions of Comparative Examples 1 and 2. In each of the rubber compositions 2 which are compositions, low heat buildup (tan δ index) and abrasion resistance (index) were good .
In addition, the rubber compositions of Examples 6 to 7 were low in heat build-up (tan δ index) and abrasion resistance (index) in the silica-blended rubber composition 3, as compared with the rubber composition of Comparative Example 3. there were.

  By using the modified conjugated diene polymer of the present invention as a rubber component of a rubber composition, a rubber composition excellent in low heat build-up and abrasion resistance can be obtained. Therefore, for passenger cars, light trucks, and light passenger cars. For light trucks, light trucks and heavy vehicles {trucks / buses, off-road tires (for construction vehicles, mining vehicles, etc.)}, and various parts of tires (especially various pneumatic radial tires), especially various It is preferably used as a rubber composition for a tread member (particularly a tread ground contact member) of a pneumatic radial tire.

Claims (5)

A compound having an amino group and a carboxyl group, a modified conjugated diene-based polymer formed by covalently bonding at least one of the terminal, main chain and side chain of the conjugated diene-based polymer,
The modified conjugated diene-based polymer, wherein the compound having an amino group and a carboxyl group is at least one compound selected from the group consisting of tyrosine and peptides of tyrosine.   The modified conjugated diene-based polymer according to claim 1, wherein the average number of amino acid residues (AA) of the compound is 1 or more and 130 or less.   The modified conjugated diene polymer according to claim 1 or 2, wherein the amount of the compound having an amino group and a carboxyl group in 100 g of the modified conjugated diene polymer is 0.005 to 55 mmol. .   The modified conjugated diene polymer according to any one of claims 1 to 3, wherein the conjugated diene polymer is natural rubber. A rubber composition comprising the modified conjugated diene-based polymer according to any one of claims 1 to 4.