WO2020262373A1 - Rubber composition for tire and pneumatic tire obtained using same - Google Patents

Abstract

The present invention provides a rubber composition which attains a high modulus with low heat build-up properties and can be vulcanized at an increased rate. A hundred parts by mass of a diene-based rubber was compounded with 1-300 parts by mass of carbon black and/or silica and 0.1-20 parts by mass of a phenolic resin having, in the molecule, at least one ethyleneamine-derived structural unit represented by –(NH-C₂H₄)-.

Description

Rubber composition for tires and pneumatic tires using it

The present invention relates to a rubber composition for a tire and a pneumatic tire using the same. Specifically, the present invention uses a rubber composition capable of achieving both high elastic modulus and low heat generation and increasing the vulcanization rate. It's about the pneumatic tires that were there.

There is known a technique for blending a thermosetting resin in a rubber composition for a tire for the purpose of increasing hardness and elastic modulus (see, for example, Patent Document 1). However, when a thermosetting resin is blended, there is a problem that heat generation is deteriorated.
On the other hand, by increasing the vulcanization rate of the rubber composition for a tire, the productivity of the tire can be improved, but there is a problem that the fracture physical properties are lowered due to the increase in modulus. Therefore, it is important to increase the vulcanization rate from the viewpoint of tire productivity, but it is necessary to balance it with other physical characteristics.

In addition, with the rise of environmental regulations due to global warming, low rolling resistance of tires is required, and in order to meet that requirement with rubber compositions for tires, higher silica content and higher compounding ratio are required. Has been performed (see, for example, Patent Document 2). High hardness and high elastic modulus are effective means to compensate for the decrease in steering stability caused by the low heat generation of the silica-blended rubber composition, but a higher-order balance between low rolling resistance and fracture physical properties. The market is demanding the change.
On the other hand, in the silica-blended rubber composition, the silanol group on the silica surface interferes with the functions of zinc oxide and the vulcanization accelerator, and the thermal conductivity is lowered, so that the vulcanization rate tends to be lowered. Therefore, the productivity of the tire can be improved by further adding a vulcanization accelerator or the like to increase the vulcanization rate, but there is a problem that the fracture physical properties are lowered due to the increase in modulus. Therefore, it is important to increase the vulcanization rate from the viewpoint of tire productivity, but it is necessary to balance it with other physical characteristics.

Japanese Unexamined Patent Publication No. 2009-269961 Japanese Unexamined Patent Publication No. 2010-13551

Therefore, an object of the present invention is to provide a rubber composition capable of increasing the vulcanization rate while achieving both high elastic modulus and low heat generation, and a pneumatic tire using the same.

As a result of intensive research, the present inventors can solve the above-mentioned problems by blending one or more kinds selected from carbon black and silica and a specific phenol resin in a specific amount with the diene rubber. We were able to complete the present invention.
That is, the present invention is derived from 1 to 300 parts by mass of one or more selected from carbon black and silica with respect to 100 parts by mass of diene rubber, and alkyleneamine represented by the following chemical formula (1) in the molecule. The present invention provides a rubber composition for a tire, which comprises 0.1 to 20 parts by mass of a phenol resin having at least one structural unit.

(In the above general formula (1), R ₁ independently represents a linear or branched alkylene group having 1 to 10 carbon atoms.)
The present invention also provides a pneumatic tire using the rubber composition for a tire of the present invention.

According to the present invention, since one or more selected from carbon black and silica and a specific phenol resin are blended in a specific amount with the diene rubber, both high elastic modulus and low heat generation property are achieved, and at the same time, It is possible to provide a rubber composition for a tire capable of increasing the vulcanization rate and a pneumatic tire using the same.
In the present invention, by blending a specific phenol resin, the silanol groups on the surface of carbon black or silica interact with the structural units derived from alkylene amine in the phenol resin to promote vulcanization and increase the elastic modulus. It is presumed that low heat generation can be achieved at the same time. In addition, high fracture physical properties can be achieved at the same time.

Hereinafter, the present invention will be described in more detail.

(Diene rubber)
The diene rubber used in the present invention is not particularly limited, and for example, natural rubber (NR), synthetic isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), acrylonitrile- Examples thereof include butadiene copolymer rubber (NBR). Of these, NR, IR and SBR are preferable. These may be used alone or in combination of two or more. The molecular weight and microstructure thereof are not particularly limited, and may be terminal-modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group, or the like, or may be epoxidized.

(Carbon black)
The carbon black used in the present invention preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 33 to 500 m ² / g from the viewpoint of improving the effect of the present invention. The nitrogen adsorption specific surface area (N ₂ SA) is a value obtained in accordance with JIS K6217-2.

(silica)
The silica used in the present invention is not particularly limited, and for example, any conventionally known silica blended in a rubber composition for tire applications can be used.
Specific examples of silica include wet silica, dry silica, fumed silica and the like. As the silica, one type of silica may be used alone, or two or more types of silica may be used in combination.
From the viewpoint of improving the effect of the present invention, the silica used in the present invention preferably has a CTAB specific surface area of 70 to 300 m ² / g, more preferably 80 to 250 m ² / g.
In the present specification, the CTAB specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface according to JIS K6217-3: 2001 "Part 3: How to obtain the specific surface area-CTAB adsorption method".

(Phenolic resin)
The phenol resin used in the present invention has at least one structural unit derived from an alkylene amine represented by the following chemical formula (1) in its molecule.

In the above general formula (1), R ₁ independently represents a linear or branched alkylene group having 1 to 10 carbon atoms. The alkylene group of R ₁ has, for example, 1 to 10, preferably 2 to 6, and more preferably 2 to 4.

From the viewpoint of improving the effect of the present invention, the phenol resin may contain at least one structural unit derived from ethyleneamine represented by the following chemical formula (2) in the molecule.

The lower limit of the content ratio of the structural unit derived from alkyleneamine or ethyleneamine in the phenol resin is, for example, 3% by mass or more, preferably 5% by mass or more, and more preferably 10% by mass or more. Thereby, the elastic modulus can be improved. On the other hand, the upper limit of the content ratio of the structural unit derived from ethyleneamine in the phenol resin may be, for example, 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less. Thereby, the softening point can be appropriately adjusted.
The content of the ethyleneamine-derived structure can be calculated based on the following formula. The nitrogen content (mass%) in the formula can be measured by an elemental analysis method.
Ethyleneamine-derived structure content = nitrogen content x (43/14)

The softening point of the phenol resin is, for example, 60 ° C. to 150 ° C., preferably 65 ° C. to 130 ° C., and more preferably 70 ° C. to 120 ° C. The softening point of the phenolic resin can be appropriately controlled according to the heating temperature at the time of heating and kneading when blended with rubber. As a result, it is possible to realize a rubber having little variation in rubber physical characteristics.

The phenolic resin may be composed of a polymer of phenols, aldehydes, and alkyleneamines. The phenolic resin may or may not contain these unreacted monomers.

Examples of phenols are not particularly limited, but for example, phenol; cresols such as orthocresol, metacresol, paracresol; 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6- Xylenol, such as 3,5-xylenol; 2,3,5-trimethylphenol, 2-ethylphenol, 4-ethylphenol, 2-isopropylphenol, 4-isopropylphenol, n-butylphenol, isobutylphenol, tert-butylphenol Alkylphenol such as hexylphenol, octylphenol, nonylphenol, phenylphenol, benzylphenol, cumylphenol, allylphenol, cardanol, ursiol, thithiol, laccol; naphthol such as 1-naphthol and 2-naphthol; fluorophenol, chlorophenol, Halogenated phenols such as bromophenol and iodophenol, monovalent phenol substitutions such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol and trinitrophenol; resorcin, alkylresorcin, pyrogallol, catechol, alkylcatechol, hydroquinone, Polyhydric phenols such as alkylhydroquinone, fluoroglucin, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalin, and naphthalene; and the like can be mentioned. These may be used alone or in combination of two or more. Among these, phenols can include one or more selected from the group consisting of phenol, cresol, xylenol and alkylphenol, and phenol can be used from an inexpensive viewpoint.

The aldehydes are not particularly limited, but for example, formaldehyde such as formalin and paraformaldehyde; trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glioxal, n-butylaldehyde, caproaldehyde, etc. Examples thereof include allyl aldehyde, benz aldehyde, croton aldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolu aldehyde and salicyl aldehyde. These aldehydes may be used alone or in combination of two or more. Among these, aldehydes can include formaldehyde or acetaldehyde, and formalin or paraformaldehyde can be used from the viewpoint of productivity and low cost.

As the alkylene amine, an aliphatic amine having one or more linear or branched alkylene groups having 1 to 10 carbon atoms in the molecule can be used. The aliphatic amine may be a compound containing one or more primary amines and / or secondary amines. For example, as aliphatic amines, diethylene triamine, triethylene tetraamine, tetraethylene pentaamine, pentaethylene hexaamine, polyethyleneimine, dipropylene triamine, tripropylene tetraamine, tetrapropylene pentaamine, pentapropylene hexaamine, polypropyleneimine and the like Examples include polyalkylene polyamines. These may be used alone or in combination of two or more.

Although the detailed mechanism is not clear, it is thought that aldehydes react with both phenols and alkyleneamines.

The catalyst used when synthesizing the phenol resin may be non-catalyst, or an acidic catalyst can be used from the viewpoint of producing a novolak type phenol resin. The acidic catalyst is not particularly limited, and examples thereof include acids such as oxalic acid, hydrochloric acid, sulfuric acid, diethyl sulfate, and paratoluenesulfonic acid, and metal salts such as zinc acetate, which may be used alone or in combination of two or more. Can be used.

Water may be used as the reaction solvent used when synthesizing the phenol resin, but an organic solvent may be used. As the organic solvent, a non-polar solvent can be used and a non-aqueous system can be used. Examples of organic solvents include, for example, alcohols, ketones, and aromatics, alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and the like, and ketones include. Acetone, methyl ethyl ketone and the like, and examples of the aromatics include toluene, xylene and the like. These may be used alone or in combination of two or more.

The molar ratio (F / P molar ratio) of phenols (P) and aldehydes (F) may be, for example, 0.2 to 1.0 mol of aldehydes with respect to 1 mol of phenols, which is preferable. Can be 0.3-0.9 mol. By setting the aldehydes in the above range, the amount of unreacted phenol can be reduced and the yield can be increased. Further, by controlling the reaction molar ratio (F / P) of phenols (P) and aldehydes (F) to 1.0 or less, that is, the phenol-rich condition in terms of molar ratio, an appropriate softening point is obtained. A phenolic resin containing a structural unit derived from an alkyleneamine having the above can be obtained, and such a phenolic resin can be satisfactorily compatible or dispersed in rubber by mixing and kneading under heating conditions.

Further, the reaction temperature may be, for example, 40 ° C. to 120 ° C., preferably 60 ° C. to 110 ° C. The reaction time is not particularly limited and may be appropriately determined according to the type of starting material, the compounding molar ratio, the amount and type of catalyst used, and the reaction conditions.

From the above, the phenolic resin used in the present invention can be obtained. The phenolic resin may contain a novolak-type phenolic resin having a novolak skeleton and a structural unit derived from the ethyleneamine in the molecule.

(Mixing ratio of rubber composition for tires)
The rubber composition of the present invention contains 1 to 300 parts by mass of one or more selected from carbon black and silica with respect to 100 parts by mass of diene rubber, and an alkylene amine represented by the chemical formula (1) in the molecule. It is characterized by blending 0.1 to 20 parts by mass of a phenol resin having at least one derived structural unit.
If the blending amount of carbon black is less than 1 part by mass, the blending amount is too small to achieve the effect of the present invention. On the contrary, if it exceeds 300 parts by mass, the heat generation property deteriorates.
If the blending amount of silica is less than 1 part by mass, the blending amount is too small to achieve the effect of the present invention. On the contrary, if it exceeds 300 parts by mass, the wear resistance and heat generation property are significantly deteriorated.
If the blending amount of the phenol resin is less than 0.1 parts by mass, the blending amount is too small to achieve the effect of the present invention. On the contrary, if it exceeds 20 parts by mass, the wear resistance and heat generation property deteriorate.

Further, in the rubber composition of the present invention, the blending amount of carbon black is preferably 1 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
The amount of silica blended is preferably 20 to 250 parts by mass with respect to 100 parts by mass of the diene rubber.
The blending amount of the phenol resin is preferably 0.1 to 20 parts by mass, and more preferably 1 to 15 parts by mass with respect to 100 parts by mass of the diene rubber.

In addition, carbon black and silica can be used together as needed.

(Other ingredients)
In addition to the above-mentioned components, the rubber composition in the present invention includes a vulcanization or cross-linking agent; a vulcanization or cross-linking accelerator; various fillers such as zinc oxide, clay, talc, and calcium carbonate; an antiaging agent; plastic. Various additives generally blended in rubber compositions such as agents can be blended, and such additives are kneaded by a general method to form a composition, which is used for vulcanization or cross-linking. Can be done. The blending amount of these additives can also be a conventional general blending amount as long as it does not contradict the object of the present invention.

In the rubber composition of the present invention, a methylene donor can be used for curing the phenol resin, and the type thereof is not particularly limited, but for example, hexamethylenetetramine and HMMM (partial condensate of hexamethoxymethylol melamine). ), Polyvalent methylol melamine derivatives such as PMMM (partial condensate of hexamethylol melamine pentamethyl ether), hexaethoxymethyl melamine, para-formaldehyde polymers, N-methylol derivatives of melamine, etc., and the effects of the present invention. From the viewpoint of improvement, hexamethylenetetramine or polyvalent methylolmelamine derivative is preferable.

The blending amount of the methylene donor is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the diene rubber.

Further, the rubber composition for a tire of the present invention can produce a pneumatic tire according to a conventional method for producing a pneumatic tire, for example, a tire cap tread, an under tread, a sidewall, a belt coat, a belt cushion, a rim cushion, and the like. It can be suitably used for inner liners, bead fillers and the like.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples. In the example, the part is based on mass unless otherwise specified.

<Synthesis of phenolic resin>
(Manufacturing Example 1)
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 1000 parts of phenol, 561 parts of a 37% formalin aqueous solution, and 55 parts of triethylenetetraamine, and reacted under reflux conditions for 2 hours. Then, the reaction was carried out at 200 ° C. for 3 hours while removing water by distillation. Further, water and unreacted monomers were distilled and removed under reduced pressure until a predetermined amount of water and free monomers were reached, and then the mixture was taken out from the reactor to obtain phenol resin 1.
The softening point of the phenol resin 1 was 110 ° C., the nitrogen content was 2.2% by mass, and the content of the ethyleneamine-derived structure was 6.8% by mass.

(Manufacturing Example 2)
Phenolic resin 2 was obtained in the same manner as in Production Example 1 except that the amount of the 37% formalin aqueous solution was 518 parts and the amount of triethylenetetraamine was 110 parts.
The softening point of the phenol resin 2 was 108 ° C., the nitrogen content was 4.1% by mass, and the content of the ethyleneamine-derived structure was 12.6% by mass.

(Manufacturing Example 3)
The phenol resin 3 was obtained in the same manner as in Production Example 1 except that the amount of the 37% formalin aqueous solution was 500 parts and the amount of triethylenetetraamine was 165 parts.
The softening point of the phenol resin 3 was 102 ° C., the nitrogen content was 6.4% by mass, and the content of the ethyleneamine-derived structure was 19.7% by mass.

Examples 1 to 6 and Comparative Examples 1 to 3
Sample Preparation In the formulation (parts by mass) shown in Table 1, the vulcanization accelerator and the components excluding sulfur were kneaded with a 1.7 liter sealed Banbury mixer for 5 minutes, and the rubber was discharged to the outside of the mixer and cooled to room temperature. .. Then, the rubber was put into the same mixer again, a vulcanization accelerator and sulfur were added, and the mixture was further kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and the unvulcanized rubber composition and the vulcanized rubber were obtained by the test method shown below. The physical properties of the test piece were measured.

Vulcanization rate (T95): In accordance with JIS K6300, the time (T95, min) to reach 95% vulcanization degree at an amplitude of 1 degree and 150 ° C. was measured with a vibrating disk vulcanization tester. The results are shown exponentially with the value of Comparative Example 1 as 100. The smaller this value is, the faster the vulcanization rate is and the better the productivity is.
Storage elastic modulus: Measured at 20 ° C. with a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho under the conditions of initial strain 10%, amplitude ± 2%, and frequency 20 Hz in accordance with JIS K6394. The results are shown exponentially with the value of Comparative Example 1 as 100. The larger this value is, the higher the elastic modulus is.
Tanδ (60 ° C.): Using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., tanδ (60 ° C.) was measured under the conditions of initial strain of 10%, amplitude of ± 2%, frequency of 20 Hz, and temperature of 60 ° C. The results are shown exponentially with the value of Comparative Example 1 as 100. The smaller this value is, the lower the heat generation is.
The results are also shown in Table 1.

The details of the numbers in Table 1 are as follows.
* 1: NR (STR20)
* 2: Carbon black (N339 manufactured by Cabot Japan, nitrogen adsorption specific surface area (N ₂ SA) = 90 m ² / g)
* 3: Straight phenolic resin (PR50731 manufactured by Sumitomo Bakelite Co., Ltd., which does not have a structural unit derived from alkyleneamine)
* 4: Phenolic resin 1 (phenol resin 1 produced in Production Example 1)
* 5: Phenolic resin 2 (phenol resin 2 produced in Production Example 2)
* 6: Phenolic resin 3 (phenolic resin 3 produced in Production Example 3)
* 7: Hexamethylenetetramine (hexamethylenetetramine manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
* 8: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 9: Stearic acid (bead stearic acid YR manufactured by NOF CORPORATION)
* 10: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu Co., Ltd.)
* 11: Sulfur (oil-treated sulfur from Hosoi Chemical Industry Co., Ltd.)
* 12: Vulcanization accelerator (Suncellor NS-P manufactured by Sanshin Chemical Industry Co., Ltd.)

From the results in Table 1, the rubber compositions of Examples 1 to 6 contained carbon black and a specific phenol resin in a specific amount with respect to the diene rubber, so that the vulcanization rate was higher than that of Comparative Example 1. The result was fast, high storage elastic modulus, and low calorific value.
On the other hand, Comparative Example 2 was an example in which a straight phenol resin and a methylene donor having no structural unit derived from alkyleneamine were used, and the vulcanization rate was slower than that of Comparative Example 1.
Comparative Example 3 is an example in which a phenol resin is not blended, and the storage elastic modulus is worse than that of Comparative Example 1.

Standard Example 1, Examples 7 to 12 and Comparative Examples 4 to 5
Sample Preparation In the formulation (parts by mass) shown in Table 2, the vulcanization accelerator and the components excluding sulfur were kneaded with a 1.7 liter sealed Banbury mixer for 5 minutes, and the rubber was discharged to the outside of the mixer and cooled to room temperature. .. Then, the rubber was put into the same mixer again, a vulcanization accelerator and sulfur were added, and the mixture was further kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and the unvulcanized rubber composition and the vulcanized rubber were obtained by the test method shown below. The physical properties of the test piece were measured.

Vulcanization rate (T30): The obtained rubber composition is vulcanized according to JIS K6300 until it reaches 30% of the maximum torque obtained from the vulcanization curve of the torque obtained at a temperature of 160 ° C. and the vulcanization time. The time (T30) was measured. The results are shown exponentially with the value of Standard Example 1 as 100. The smaller this value is, the faster the vulcanization rate is and the better the productivity is.
Storage elastic modulus: Measured by the same method as above. The results are shown exponentially with the value of Standard Example 1 as 100. The larger this value is, the higher the elastic modulus is.
tan δ (60 ° C.): Measured by the same method as above. The results are shown exponentially with the value of Standard Example 1 as 100. The smaller this value is, the lower the heat generation is.
Breaking strength (TB): Tested at 20 ° C. according to JIS K 6251. The results are shown exponentially with the value of Standard Example 1 as 100. The larger this value is, the higher the breaking strength is.
The results are also shown in Table 2.

The details of the numbers in Table 2 are as follows.
* 1: SBR (E581 manufactured by Asahi Kasei Corporation, oil spread = 37.5 parts by mass with respect to 100 parts by mass of SBR)
* 2: BR (Nipol BR1220 manufactured by Zeon Corporation)
* 3: Silica (ZEOZIL 1165MP manufactured by Solvay, CTAB specific surface area = 155m ² / g)
* 4: Carbon black (N339 manufactured by Cabot Japan)
* 5: Cashew-modified phenolic resin (PSM-9450 manufactured by Sumitomo Bakelite Co., Ltd., which does not have a structural unit derived from alkyleneamine)
* 6: Phenolic resin 1 (Phenolic resin 1 produced in Production Example 1)
* 7: Phenolic resin 2 (phenol resin 2 produced in Production Example 2)
* 8: Phenolic resin 3 (phenolic resin 3 produced in Production Example 3)
* 9: Hexamethylenetetramine (Suncellor HT-PO manufactured by Sanshin Chemical Industry Co., Ltd.)
* 10: Silane coupling agent (Si69 manufactured by Evonik Industries)
* 11: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 12: Stearic acid (bead stearic acid YR manufactured by NOF CORPORATION)
* 13: Anti-aging agent (6PPD manufactured by EASTMAN)
* 14: Wax (paraffin wax manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
* 15: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu Co., Ltd.)
* 16: Sulfur (oil-treated sulfur from Hosoi Chemical Industry Co., Ltd.)
* 17: Vulcanization accelerator 1 (Suncellor CM-G manufactured by Sanshin Chemical Industry Co., Ltd.)
* 18: Vulcanization accelerator 2 (Sulfur DG manufactured by Sumitomo Chemical Co., Ltd.)

From the results in Table 2, the rubber compositions of Examples 7 to 12 contained silica and a specific phenol resin in a specific amount with respect to the diene rubber, so that the vulcanization rate was faster than that of Standard Example 1. As a result, the storage elastic modulus was high, the heat generation was low, and the breaking strength was high.
On the other hand, in Comparative Example 4, since the phenol resin was not blended, the vulcanization rate was slower than that in Standard Example 1, and the storage elastic modulus and the breaking strength were inferior.
Comparative Example 5 is an example in which a methylene donor was blended with Standard Example 1, and the result was that the vulcanization rate was slower than that of Standard Example 1. In addition, no improvement was seen in the breaking strength.

Standard Examples 2-5, Examples 13-25 and Comparative Examples 6-9
Sample preparation In the formulation (parts by mass) shown in Tables 3 and 4, the vulcanization accelerator and the components excluding sulfur were kneaded in a 1.7 liter sealed Banbury mixer for 5 minutes, and the rubber was released to the outside of the mixer to room temperature. Cooled. Then, the rubber was put into the same mixer again, a vulcanization accelerator and sulfur were added, and the mixture was further kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and the unvulcanized rubber composition and the vulcanized rubber were obtained by the test method shown below. The physical properties of the test piece were measured.

Storage elastic modulus: Measured by the same method as above. The results are shown exponentially with the value of each standard example as 100. The larger this value is, the higher the hardness is.
Breaking strength (TB): Measured by the same method as above. The results are shown exponentially with the value of each standard example as 100. The larger this value is, the higher the breaking strength is.
Exothermic (tan δ60 ° C.): Measured by the same method as above. The results are shown exponentially with the value of each standard example as 100. The smaller this value is, the lower the heat generation is.
The results are also shown in Tables 3 and 4.

In addition, Examples 13 to 15 were compared with Standard Example 2, Examples 16 to 19 and Comparative Examples 6 to 7 were compared with Standard Example 3, and Examples 20 to 22 were compared with Standard Example 4, and Example 23. ~ 25 and Comparative Examples 8-9 are compared with Standard Example 5.

The details of the numbers in Tables 3 and 4 are as follows.
* 1: NR (STR20)
* 2: SBR (Nipol 1502 manufactured by Zeon Corporation)
* 3: Carbon black HAF (Cabot Japan N330T, nitrogen adsorption specific surface area (N ₂ SA) = 70 m ² / g)
* 4: Carbon black GPF (Cabot Japan N660, nitrogen adsorption specific surface area (N ₂ SA) = 36 m ² / g)
* 5: Straight phenolic resin (PR50731 manufactured by Sumitomo Bakelite Co., Ltd., which does not have a structural unit derived from alkyleneamine)
* 6: Phenolic resin 1 (Phenolic resin 1 produced in Production Example 1)
* 7: Phenolic resin 2 (phenol resin 2 produced in Production Example 2)
* 8: Phenolic resin 3 (phenolic resin 3 produced in Production Example 3)
* 9: Methylene donor (hexamethylenetetramine manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
* 10: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 11: Stearic acid (bead stearic acid YR manufactured by NOF CORPORATION)
* 12: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu Co., Ltd.)
* 13: Sulfur (oil-treated sulfur from Hosoi Chemical Industry Co., Ltd.)
* 14: Vulcanization accelerator (Noxeller CZ-G manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)

From the results in Tables 3 and 4, it was found that the rubber compositions of Examples 13 to 25 can simultaneously achieve high hardness, high breaking strength and low heat generation as compared with each standard example.
On the other hand, in Comparative Examples 6 and 8, since the specific phenol resin was not blended, the hardness was lowered.
In Comparative Examples 7 and 9, since the blending amount of the specific phenol resin exceeded the upper limit specified in the present invention, the breaking strength was not improved and the heat generating property was deteriorated.

Standard Example 6, Examples 26-31 and Comparative Examples 10-11
Sample Preparation In the formulation (parts by mass) shown in Table 5, the vulcanization accelerator and the components excluding sulfur were kneaded with a 1.7 liter sealed Banbury mixer for 5 minutes, and the rubber was discharged to the outside of the mixer and cooled to room temperature. .. Then, the rubber was put into the same mixer again, a vulcanization accelerator and sulfur were added, and the mixture was further kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and the unvulcanized rubber composition and the vulcanized rubber were obtained by the test method shown below. The physical properties of the test piece were measured.

Vulcanization rate (T95): Measured by the same method as above. The results are shown exponentially with the value of Standard Example 6 as 100. The smaller this value is, the faster the vulcanization rate is and the better the productivity is.
Exothermic (tan δ60 ° C.): Measured by the same method as above. The results are shown exponentially with the value of Standard Example 6 as 100. The smaller this value is, the lower the heat generation is.
Breaking strength (TB): Measured by the same method as above. The results are shown exponentially with the value of Standard Example 6 as 100. The larger this value is, the higher the breaking strength is.
Abrasion resistance: Using a lambourn abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd., the abrasion was measured under the conditions of a load of 15 N, a slip ratio of 25%, a time of 10 minutes, and room temperature to determine the abrasion loss. The results are shown exponentially with the value of Standard Example 6 as 100. The larger the index, the better the wear resistance.
The results are also shown in Table 5.

The details of the numbers in Table 5 are as follows.
* 1: SBR (SBR E581 manufactured by Asahi Kasei Corporation, oil spread = 37.5 parts by mass with respect to 100 parts by mass of SBR)
* 2: BR (Nipol BR1220 manufactured by Zeon Corporation)
* 3: Silica (ULTRASIL 9100GR manufactured by Evonik, CTAB specific surface area = 210 m ² / g)
* 4: Carbon black (N339 manufactured by Cabot Japan)
* 5: Cashew-modified phenolic resin (PSM-9450 manufactured by Sumitomo Bakelite Co., Ltd., which does not have a structural unit derived from alkyleneamine)
* 6: Phenolic resin 1 (Phenolic resin 1 produced in Production Example 1)
* 7: Phenolic resin 2 (phenol resin 2 produced in Production Example 2)
* 8: Phenolic resin 3 (phenolic resin 3 produced in Production Example 3)
* 9: Silane coupling agent (Si69 manufactured by Evonik)
* 10: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 11: Stearic acid (bead stearic acid YR manufactured by NOF CORPORATION)
* 12: Anti-aging agent (6PPD manufactured by EASTMAN)
* 13: Wax (paraffin wax manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
* 14: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu Co., Ltd.)
* 15: Sulfur (oil-treated sulfur from Hosoi Chemical Industry Co., Ltd.)
* 16: Vulcanization accelerator CBS (Suncellor CM-G manufactured by Sanshin Chemical Industry Co., Ltd.)
* 17: Vulcanization accelerator DPG (Sulfur DG manufactured by Sumitomo Chemical Co., Ltd.)
* 18: Terminal-modified SBR (Toughden F3420 manufactured by Asahi Kasei Corporation. The terminal is modified with a glycidylamine group.)

From the results in Table 5, the rubber compositions of Examples 26 to 31 are simultaneously improved in heat generation, breaking strength and wear resistance as compared with Standard Example 6.
On the other hand, in Comparative Example 10, since the specific phenol resin was not blended, the breaking strength was deteriorated.
In Comparative Example 11, since the blending amount of the specific phenol resin exceeded the upper limit specified in the present invention, the heat generating property and the breaking strength deteriorated.

Claims (7)

1 to 300 parts by mass of one or more selected from carbon black and silica with respect to 100 parts by mass of diene rubber, and at least 1 structural unit derived from alkylene amine represented by the following chemical formula (1) in the molecule. A rubber composition for a tire, which comprises 0.1 to 20 parts by mass of a phenol resin having one or more of them.

(In the above general formula (1), R ₁ independently represents a linear or branched alkylene group having 1 to 10 carbon atoms.) The rubber composition for a tire according to claim 1, wherein the phenol resin has at least one structural unit derived from ethyleneamine represented by the following chemical formula (2) in the molecule.

The rubber composition for a tire according to claim 2, wherein the content ratio of the structural unit derived from ethyleneamine in the phenol resin is 3% by mass or more and 50% by mass or less. The rubber composition for a tire according to claim 1, wherein the softening point of the phenol resin is 60 ° C. or higher and 150 ° C. or lower. The rubber composition for a tire according to claim 1, wherein 0.1 to 5 parts by mass of methylene donor is further blended with respect to 100 parts by mass of the diene rubber. The rubber composition for a tire according to claim 5, wherein the methylene donor is hexamethylenetetramine or a polyvalent methylolmelamine derivative. A pneumatic tire using the rubber composition for a tire according to claim 1.