JPH01153740A - Rubber composition having low heat build-up property - Google Patents

Abstract

PURPOSE:To obtain a rubber composition giving a low fuel-cost tire having remarkably improved heat build-up property and good abrasion resistance and antiskid property, by compounding a specific modified polymer with carbon black. CONSTITUTION:The objective composition is produced by compounding (A) 100pts.wt. of a raw rubber containing 30wt.% of a polymer produced by reacting (a) a rubbery polymer added with an alkali metal or alkaline-earth metal with (b) a compound selected from an organic compound containing the group of formula I (X is O or S) in the molecule, amino group-containing benzophenones, amino group-containing thiobenzophenones, aminobenzene derivative of formula II (R is H or organic group; n is 1-4), an isocyanate compound, a mono functional or bifunctional active tin compound, etc., with (B) 20-150pts.wt. of a carbon black having a specific surface area of >=75m<2>/g (determined by nitrogen adsorption) and having an H2 generation at 1,300 deg.C and a mode diame ter (Dst, mmu) satisfying the formula H2>3.74-0.02(Dst).

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a low heat build-up rubber composition, more specifically, a low heat build-up rubber composition that has significantly improved heat build-up properties without impairing wear resistance, skid resistance, etc. The present invention relates to a rubber composition.

[Prior art]

In response to social demands for resource and energy conservation, the rubber industry, particularly the tire industry, has been actively developing fuel-efficient tires over the past few years. A low heat build-up rubber composition is essential for the development of such fuel-efficient tires, and many inventions in this field have recently been published.

For example, JP-A-5542133, JP-A-56-1
27650, etc., high vinyl polybutadiene rubber (v-BR) is used, while JP-A-57-55204 and JP-A-57-73030 use high vinyl styrene-butadiene copolymer rubber (V-BR). 3BR) has been proposed and has been shown to be effective in improving grip performance and heat generation.

Also, JP-A-59-117514, JP-A-61-
103902, JP 61-14214, and JP 61-141741 disclose rubber compositions by using modified polymers in which functional groups such as benzophenone and isocyanate are introduced into the polymer molecular chains. A method is shown to reduce the exothermic nature of

However, even if these V-BR, V-3BR or modified polymers are used, the recent demands for low heat build-up have not been fully satisfied, and rubber compositions with even lower heat build-up are desired. .

On the other hand, generally known methods for obtaining rubber compositions with low heat build-up include using carbon blanks with large particle diameters or reducing the amount of carbon black blended. Poor breaking strength and wear resistance, making it impractical. Also, special public service in 1983
Publication No. 2451 shows that carbon black with a wide aggregate distribution improves heat generation properties.
Even with this carbon blank, a sufficiently satisfactory heat generation property cannot be obtained.

Furthermore, Japanese Patent Publication No. 50-38181, U.S. Patent No. 2
815856 and the like describes that the heat generation properties of rubber compositions are improved by adding nitrosoquinolines, nitrosoanilines, etc. however,
When such nitroso compounds are added to polyisoprene rubber, they have a drawback that they have a large saccharifying effect on the polymer and reduce the abrasion resistance of the rubber composition. Furthermore, when added to other diene rubbers, the heat generation property cannot be improved sufficiently.

As described above, many inventions have been made to improve the heat generation properties of rubber compositions, but a rubber composition with low heat generation properties that fully satisfies the recent advanced demands for fuel-efficient tires has not yet been obtained. At present, the invention of such a rubber composition has been highly desired.

The present inventors have developed a heat-generating material by using a combination of a so-called modified polymer in which a functional group is introduced into the polymer molecular chain and carbon black with high surface activity, which is said to be effective in improving wear resistance. It has been found that this can be significantly improved, leading to the present invention.

That is, a modified polymer in which a functional group is introduced into the polymer molecular chain is effective in improving heat generation properties as shown in the above-mentioned publication, and on the other hand, a modified polymer with a high surface activity, that is, 120
It has been shown in Japanese Unexamined Patent Publication No. 61-207452 that carbon black, which generates a large amount of hydrogen (H2 amount) at high temperatures of 0 to 1300°C, is effective in improving wear resistance. All of these inventions focus on the polymer itself or the carbon black itself. The present inventors believe that the characteristics of modified polymers or activated carbon black are developed due to the stronger interaction between the polymer and carbon black at the interface, and therefore, the modified polymer and carbon black with high surface activity were used simultaneously. It was thought that this would further strengthen the polymer/carbon black interaction and further improve heat generation properties, fracture strength, etc. As a result, by using a modified polymer and highly surface-active carbon black together, we found that the effect of improving heat generation obtained by the modified polymer and the effect obtained by the activated carbon blank is as follows: It was possible to find a greater effect of improving heat generation (synergistic effect) than the additive effect, leading to the present invention.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a low heat build-up rubber composition that has significantly improved heat build-up properties without impairing wear resistance, skid resistance, etc.

[Structure of the invention]

For this reason, the present invention provides an alkali metal and/or alkaline earth metal addition rubbery polymer, an organic compound having 10 N< bonds in the molecule (wherein X represents 0 or an S atom j), Benzophenones having an amino group and/or substituted amino group, an amino group and/or
or aminobenzene derivatives, isocyanate compounds, monofunctional or difunctional thiobenzophenones having a substituted amino group (wherein R represents hydrogen or an organic group, and n represents an integer of 1 to 4) A raw material containing at least 30% by weight of a polymer obtained by reacting with one or more compounds selected from active tin compounds, reactive compounds having thioether groups, carbodiimides, carbon disulfide, xanthogen compounds, and dithioic acid compounds. rubber 10
0 parts by weight, nitrogen adsorption specific surface area (NASA) is 75
The most frequent mode diameter of aggregate distribution by centrifugal sedimentation method is
The gist of the present invention is a low heat build-up rubber composition, which is characterized in that 20 to 150 parts by weight of carbon black having a relationship with Dst, mμ) expressed by the following formula is blended and placed.

H2> 3.74 0.02 (Dst) Hereinafter, the configuration of the present invention will be explained in detail.

(1) Raw rubber.

an alkali metal and/or alkaline earth metal addition rubbery polymer, an organic compound having 10 N< bonds (in the formula, X represents an O or S atom) in the molecule, an amino group and/or
or benzophenones having a substituted amino group, thiobenzophenones having an amino group and/or a substituted amino group, aminobenzenes represented by (wherein R represents hydrogen or an organic group, and n represents an integer from 1 to 4) one or more compounds selected from derivatives, isocyanate compounds, monofunctional or difunctional active tin compounds, reactive compounds having a thioether group, carbodiimides, carbon disulfide, xanthogen compounds, and dithioic acid compounds. It contains at least 30% by weight of the polymer obtained by the reaction. If the content of the obtained polymer is less than 30% by weight, the exothermic property will not be sufficiently improved even if active carbon black is used in combination. In order to produce this polymer, 0.2 to 5 of the above-mentioned one or more compounds should be added per 1 mole of the above-mentioned rubbery polymer.
The reaction may be carried out in moles, preferably 0.5 to 2 moles. Introduction of functional groups through this reaction can be easily carried out by adding these compounds after the completion of polymerization of the above-mentioned rubber-like polymer, but it is also possible to introduce functional groups by a method such as carrying out polymerization with an initiator having a functional group. Any method may be used as long as a functional group is introduced into the polymer chain.

(al　rubber-like polymer.

The rubbery polymer into which the functional group is introduced is a diene polymer produced by solution polymerization using an alkali metal and/or alkaline earth metal catalyst. For example, 1,3-butadiene, isoprene, ■, 3-pentadiene, ■, 3-
It is a homopolymer or copolymer of conjugated diene monomers containing hexadiene and the like. In particular, when used in tires, polybutadiene rubber, styrene-butadiene copolymer rubber, and polyisoprene rubber are preferred, but the rubber is not limited to these.

(bl An organic compound having a -C->< bond (in the formula, X represents 0 or an S atom) in the molecule.

Examples include formamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide,
N,N-dimethylacetamide, N,N-diethylacetamide, aminoacetamide, N,N-dimethyl-N
', N'-dimethylaminoacetamide, N', N-
Dimethylaminoacetamide, N'-ethylaminoacetamide, N,N-dimethyl-N'-ethylaminoacetamide, N.

N-dimethylaminoacetamide, N-phenyldiacetamide, acrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide propionamide, N,N-dimethylpropionamide, 4-pyridylamide, N,N-dimethyl -4-pyridylamide,
Benzamide, N-ethylbenzamide, N-phenylbenzamide, N,N-dimethylbenzamide, p-aminobenzamide, N',N'-(p-dimethylamino)benzamide, N',N'-(p-diethylamino)
Benzamide, N'-(p-methylamino)benzamide, N'-(p-ethylamino)benzamide, N, N
-dimethyl-N'-(p-ethylamino)benzamide, N,N-dimethyl-N', N'-(p-diethylamino)benzamide, N,N-dimethyl-p-aminobenzamide, N-methyldibenzamide, N~acetyl N-2-naphthylbenzamide, succinic acid amide, maleic acid amide, phthalic acid amide, N, N, N', N
-tetramethylmaleic acid amide, N, N, N',
N'-tetramethylphthalic acid amide, succinimide,
N-methylsuccinimide, maleimide, N-methylmaleimide, phthalimide, N-methylphthalimide, oxalamide, N,N,N', N'-tetramethyloxamide, N,N-dimethyl-p-amino-ben zalacetamide, nicotinamide, N,N-diethylnicotinamide, C2-cyclohexanedicarboximide, N-methyl-1,2-cyclohexanedicarboximide, methyl carbamate, N-methyl-methyl carbamate, N,
Amides and imides such as N-diethyl-ethyl carbamate, ethyl carbanylate, p-N, N-diethylamino-ethyl carbanylate; urea, N, N'-dimethylurea, N, N, N', N' -Ureas such as tetramethylurea; formanilide, N-methylacetanilide,
Anilides such as aminoacetanilide, benzanilide, p,p'-di(N,N-diethylaminobenzanilide); ε-caprolactam, N-methyl-ε-caprolactam, N-acetyl-ε-caprolactam, 2-pyroIJFn , N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, 2-piperidone, N-methyl-2-pyrrolidone
- Lactams such as piperidone, 2-quinolone, N-methyl-2-quinolone, 2-indolinone, N-methyl-2-indolinone; isocyanuric acid, N, N', N#
Examples include isocyanuric acids such as -1-limethylisocyanuric acid and their corresponding sulfur-containing compounds. Particularly preferred compounds are those in which an alkyl group is bonded to nitrogen.

(C1 benzophenones, thiobenzophenones.

Examples of benzophenones and thiobenzophenones having an amino group and/or substituted amino group include 4-aminobenzophenone, 4-dimethylaminobenzophenone,
4-dimethylamino-4'-methylbenzophenone, 4
, 4'-diaminobenzophenone, 4,4'-bis (
dimethylamino)hensiphenone, 4,4'-bis (
diethylamino)benzophenone, 4,4'-bis (
ethylamino)benzophenone, 3,3'-dimethyl-
4,4'-bis(diethylamino)benzophenone,
3゜3'-dimethoxy-4,4'-bis(dimethylamino)hensiphenone, 3.3', 5.5'-tetraaminobenzophenone, 2,4.6-) riaminobenzophenone, 3.3', 5 Examples include 5'-tetra (diethylamino)benzophenone and the like and their corresponding thiobenzophenones. The substituted amino group is particularly preferably one having an alkyl group, particularly a dialkyl-substituted amino group. Substituents other than amino groups and substituted amino groups may be present as long as they do not adversely affect the reaction.

(d) Aminobenzene derivative.

This is a compound represented by the following formula.

In the formula, R represents hydrogen or an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group, or an alkenyl group. X is halogen,
Indicates an ester group or a nitrile group. n represents an integer from 1 to 4.

Examples of this compound include p-aminoethylbenzoate, p-aminobutylbenzoate, O-amino-
Examples include p-methylethylbenzoate, 0-aminomethylbenzoate, p-aminopropylbenzoate, 0-aminobenzonitrile, p-aminobenzonitrile, m-aminobenzonitrile and the like.

Further examples include N-bis(trimethylsilyl)aminobenzene derivatives obtained by trimethylsilylating the amino group of these aminobenzene derivatives. As a specific example, p-N
-bis(trimethylsilyl)aminoethylbenzoate, p-N-bis(trimethylsilyl)aminobutylbenzoate, o-N-bis(trimethylsilyl)amino-
p-Methyl-ethylbenzoate, 0-N-bis(trimethylsilyl)methylhenshade, p-N-bis(trimethylsilyl)propylbenzoate, 0-bis(trimethylsilyl)benzonitrile, p-bis(trimethylsilyl)benzonitrile, m- Examples include bis(trimethylsilyl)benzonitrile.

(e) Isocyanate compound.

For example, phenyl isocyanate, hexanotylene diisocyanate, 2,4-tolylene diisocyanate,
2.6-) Lylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolylene diisocyanate, triphenylmethane triisocyanate, polymeric diphenylmethane diisocyanate, p-phenylene diisocyanate, tris(isocyanatophenyl) ) thiophosphate, xylylene diisocyanate, benzene-1,2,4-) diisocyanate, naphthalene-1,2,5,7-titraisocyanate, naphthalene-1,3,7-) diisocyanate, various Aromatic polyisocyanates, dimers or trimers of various isocyanate compounds, adducts obtained by reacting the above-mentioned isocyanates with polyols, polyamines, and the like can be used alone or in combination of two or more.

(f) Active tin compound.

Monofunctional or difunctional active tin compounds contain one or two halogen-tin bonds, alkoxy-tin bonds, ester-tin bonds, and benzyl-tin bonds in one molecule. It is a compound. Specifically, trimethyltin chloride, tributyltin chloride, trioctyltin chloride, tributyltin bromide, dibutyltin dichloride, dioctyltin chloride, phenyltributyltin, methoxytributyltin, and the like are used.

(gl　Reactive compound having a thioether group.

Reactive compounds having a thioether group include all R-3-R'-C-X that can react with the living end to introduce a thioether group into the polymer molecule.
, S+R'-CX)z (wherein R is alkyl, allyl, R' is alkylene, arylene, M is oxygen or sulfur,
represents alkyl, allyl, alkoxy) and I (R-3-R'-C), l-X (wherein R, R', and M have the same meanings as in the preceding, and X represents alkylene, arylene , represents alkyleneoxy, oxygen, sulfur, and when X represents these, n is 2, and when X represents a polyhydric alcohol residue, n represents a number equal to the number of alcohol groups) It is one type or a mixture of two or more selected compounds. Examples of these compounds include methyl acetone, 1-butylthiohexanone-3,2-laurylthiophenyl ketone, 2-octylthioethylbenzyl ketone, 2-phenylthiophenyl ketone, p-laurylthiobenzophenone, p-
laurylthioacetophenone, methyl methylthioglycolate, ethyl β-ethylthiopropionate, ethyl α-ethylthiopropionate, hexyl β-propylthiopropionate, lauryl β-ethylthiopropionate,
myristyl β-octylthiopropionate, stearyl β-laurylthiopropionate, stearyl β-stearylthiopropionate, stearyl β-benzylthiopropionate, stearyl β-p-tolylthiopropionate, β-2,5-xylylthio Stearyl propionate, methyl p-laurylthiobenzoate, methyl 0-laurylthiobenzoate, benzyl p-laurylthiobenzoate,
Phenyl p-laurylthiobenzoate, ethyl γ-methylthiobutyrate, ethyl 2-methylthioethanecarbodithioate, dimethyl thiodiglycolate, β.

β'-dimethyl thiodipropionate, β,β'-dilauryl thiodipropionate, β,β'-similistyl thiodipropionate, β,β'-distearyl thiodipropionate, α,α'-thiodipropionate Dimethyl propionate, dimethyl thiobisdithioglycolate, 1,6-dimethylthiohexadione-2,5, ethylenebismethylthioglycolate, glycerin-tri-β-laurylthiopropionate, pentaerythritol-tetrakis-β-laurylthiopropionate Examples include ester, methylthioglycolic anhydride, and methylthiodithioglycolic anhydride.

(hl Carbodiimides.

As carbodiimides, disubstituted carbodiimide compounds having a general formula -N=C=N- bond or general formula>N-
C1: a disubstituted cyanamide compound having an N bond,
A compound containing dialkylcarbodiimide, alkylaryl-carbodiimide, diarylcarbodiimide, dialkyl cyanamide, alkylaryl cyanamide, and diaryl cyanamide, which can be used singly or as a mixture of two or more.

For example, dimethylcarbodiimide, diethylcarbodiimide, dipropylcarbodiimide, dibutylcarbodiimide, diarylcarbodiimide, dicyclohexylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, methylpropylcarbodiimide, butylcyclohexylcarbodiimide, ethylbenzylcarbodiimide, propylphate. Nylcarbodiimide, phenylbenzylcarbodiimide , dimethyl cyanamide, diethyl cyanamide, dipropyl cyanamide, dibutyl cyanamide, dihexyl cyanamide, dicyclohexyl cyanamide, dibenzyl cyanamide, diphenyl cyanamide, methylpropyl cyanamide, butylcyclohexyl cyanamide, ethylbenzyl cyanamide, propylphenyl cyanamide, phenylbenzyl cyanamide, etc. be. Among these, particularly preferred are dicyclohexylcarbodiimide, diphenylcarbodiimide and diphenyl cyanamide.

fit carbon disulfide.

Commercially available carbon disulfide may be used.

fJ) Xanthogen compound.

The xanthogen compound is a compound having the general formula R-0-(, -3-, for example, methylxanthate, ethylxanthate, n-propylxanthate, isopropylxanthate, n
- Alkylxanthogenic acids such as -butylxanthogenic acid, 5ec-butylxanthogenic acid, n-hexylxanthogenic acid, n-octylxanthogenic acid, etc., phenylxanthogenic acid, p-tolylxanthogenic acid, etc., and xanthogens thereof Lithium, sodium and potassium salts of acids and dimethylxanthogen disulfide, diethylxanthogen disulfide,
Di-n-propylxanthogen disulfide, diisopropylxanthogen disulfide, di-n-butylxanthogen disulfide, di-5ec-butylxanthogen disulfide, di-n-hexylxanthogen disulfide, diphenylxanthogen disulfide, di-p
- Xanthogen disulfides such as tolyl xanthogen disulfide are preferably used. Among these, xanthogen disulfides such as dimethylxanthogen disulfide, diisopropylxanthogen disulfide, di-n-hexylxanthogen disulfide, and diphenylxanthogen disulfide are particularly preferred.

(kl Dithioic acid compound.

Examples of dithioic acid compounds include compounds having the general formula: Lithium, sodium, and potassium salts, as well as thioacyl sulfides derived therefrom and dithioic acid esters such as methyl dithioacetate, ethyl dithioacetate, and butyl ethanecarbodithioate are preferably used. Among these, dithioic acid esters such as methyl dithioacetate, ethyl dithioacetate, and butyl ethanecarbodithioate are particularly preferred.

(2) Carbon black.

The carbon black used in the present invention has a nitrogen adsorption specific surface area (N2SA) of 75 m/g or more. 75
If it is less than m/g, the heat generation property is excellent, but the strength and abrasion resistance are insufficient. In addition, highly active carbon black means that the amount of hydrogen (L amount) generated at 1300°C is the most frequent mode diameter (Dst, m
μ) means a carbon blank that has the relationship of the following formula.

Hz > 3.74 0.02 (Dst) A carbon blank with a large amount of generated hydrogen is in a state where the carbon microcrystalline structure is insufficiently formed and the particle surface is enriched with chemically active radicals. Generally, the amount of hydrogen generated (amount of H2) is determined by the reaction time in the carbon black production process,
It is known that it is closely related to reaction temperature, etc.
The amount of hydrogen generated (amount of H2) and the most frequent mode diameter (Dst) of carbon black aggregates have the following correlation. However, the carbon black used in the present invention has a unique property with high surface activity by setting the generated hydrogen amount (Hz amount) to be larger than the value calculated by the 3.74-0.02 (Dst) formula. It has become a thing.

The amount of hydrogen generated (l (2 amounts) is 3.74 0.02 (Dst
) Carbon black having a value equal to or smaller than that is not preferred because not only the heat generation property cannot be sufficiently improved, but also the abrasion resistance decreases.

The blending amount of carbon black is in the range of 20 to 150 parts by weight per 100 parts by weight of the raw rubber. If the amount is less than 20 parts by weight, the heat generation property will be improved, but the breaking strength and abrasion resistance will be poor, which is not preferable. On the other hand, if it exceeds 150 parts by weight, the heat generation property will not be improved.

In addition, in the present invention, other compounding agents normally used in the rubber industry, such as fillers, softeners, plasticizers, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc., may be added as necessary. It doesn't matter.

Examples and comparative examples will be shown below, but the invention is not limited to these examples as long as they do not go beyond the gist of the present invention.

Examples and Comparative Examples Each component was blended according to the formulation content (parts by weight) shown in Table 1 below, and the raw rubber and compounding agents excluding the vulcanization accelerator and sulfur were 1.7 jl! After mixing for 5 minutes using a Banbury mixer, the mixture was kneaded with a vulcanization accelerator and sulfur for 4 minutes using an 8-inch test kneading roll machine to obtain a rubber composition. These rubber compositions were press-vulcanized at 160°C for 30 minutes,
A target test piece was prepared, various tests were conducted, and its physical properties were measured. The results are shown in Table 4 below. The properties of the polymer and carbon black used are shown in Tables 2 and 3.
are shown respectively.

Table 1 Polymer 100 parts by weight Carbon blank 50 parts by weight Zinc oxide 3 Parts by weight Stearic acid 1.5 parts by weight Aromatic oil 5 Parts by weight Vulcanization accelerator 1.0 parts by weight Sulfur
1.75 parts by weight Note) This I N-cyclohexyl-2-benzthiazylsulfenamide.

note) *2 N1pol 1502 (manufactured by Nippon Zeon).

*3 Except for 5BR-1, manufactured by solution polymerization using an alkyl lithium catalyst. Note that the introduction of the functional group was carried out by adding a compound containing a functional group immediately before stopping the polymerization.

*4 Measured by H-NMR method.

*5 Measured according to JIS K 6300.

(Margins below this page) note) Zero 6 Geest 9 (manufactured by Tokai Carbon Co., Ltd.).

*7 ASTM D 3037 (1984) Meth
Measured by odC.

*8 Measured according to JIS K 6221.

*9 Measurement was carried out by centrifugal sedimentation method using a disk centrifugation manufactured by Joyce Lebre in the following manner.

That is, carbon black dried and accurately weighed according to JIS K6221 (1982) 5 method was mixed with 20% ethanol.
After adding the carbon black to an aqueous solution and adjusting the carbon black concentration to 0.005% by weight, it was sufficiently dispersed using ultrasonic waves to prepare a sample.

On the other hand, the rotation speed of the disc centrifuge was set to 800O.
rpm and add 10ml of spin liquid (distilled water) to this disc centrifuge, then
ml of buffer solution (20% by volume ethanol aqueous solution) was injected. Next, add 0.5 to 1.0 ml of the sample solution to this.
was added with a syringe to start centrifugal sedimentation, and an aggregate distribution curve was created by photoelectric precipitation, and the aggregate diameter of the mode was taken as the most frequent mode diameter Dst.

*10 Carbon black was heated to 1300 under the following conditions.
The amount of hydrogen generated at ℃ is expressed as a number of square meters per gram of carbon blank. First, 10 cm of carbon black was heated to 1300°C for 120 seconds (20 seconds x
(6 times) thermal decomposition, and the generated gas is introduced into a connected gas chromatograph (Shimadzu GC-9A). At this time, nitrogen gas is introduced as a carrier gas at a constant flow rate (30 ml/min).

The gas chromatography analysis method uses the TCD method,
The conditions are as follows.

Column: Molecular sieve, 58 3 mφ x 3 m Sample injection temperature: 100'c Column temperature = 40°C Carrier gas: Nitrogen gas, 30 ml The amount of hydrogen generated per 1Z is determined in advance by mixing a predetermined amount (lee of hydrogen gas with air and adding 1β The area-weight (■) of the amount of hydrogen (using 1 cc) was determined in advance and determined by the area method.

(Margins below this page) Note) <tanδ> Measured at 0°C and 60°C using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of elongation deformation with a strain rate of 10 ± 2% and a frequency of 20 Hz. The jan δ value at 0° C. corresponds to the wet skid resistance value, and the jan δ value at 60° C. corresponds to the exothermic property. The smaller the jan δ value at 60°C, the smaller the heat generation, and the higher the fuel efficiency when used in tires.

<Resilience> Resilience was measured according to the method of JIS K 6301 at 60°C. The higher the value, the lower the heat generation.

<Abrasion resistance> Measured using a Pico abrasion tester in accordance with ASTM D2228, and expressed as an index ((wear amount of Comparative Example 1) x 100/(wear amount of sample)). Therefore, the larger the value, the better the wear resistance.

<Tensile properties> Measured in accordance with JIS K 6301.

As is clear from the physical properties table in Table 4, Example 1 in which a modified polymer with functional groups introduced and activated carbon black were used together.
~6 is clearly 60% higher than the corresponding comparative example.
It can be seen that the tan δ at °C or impact resilience is improved, and the material has excellent low heat generation properties.

For example, in Comparative Examples 8 to 10, Comparative Example 8 and Comparative Example 9
When compared, the effect of activated carbon black is that impact resilience is improved by 0.3%.

Further, from a comparison of Comparative Examples 8 and 10, it can be seen that the impact resilience is improved by 4.2% as an effect of the modified polymer. Therefore, it is estimated that the improvement effect by using the modified polymer and activated carbon blank in combination is at most 4.5%, but in Example 3 or 4 according to the present invention, it is actually 8.1%.
An improvement of ~8.3% was observed, clearly demonstrating the combined effect of the modified polymer and activated carbon blank.

The above matters are summarized in FIG. 1 for the SBR polymers shown in Table 4. FIG. 1 shows the relationship between abrasion resistance and impact resilience in the SBR system.

In the figure, the circle and the numbers inside each represent the numbers of the comparative example and the example. It is clear from this figure that the use of the rubber composition of the present invention significantly improves heat generation properties without impairing wear resistance. Therefore, the rubber composition of the present invention can be suitably used, for example, as a rubber composition for treads of fuel-efficient tires.

〔Effect of the invention〕

As explained above, according to the present invention, by using a so-called modified polymer in which a functional group has been introduced into the molecular chain (for example, benzophenone, etc.) and carbon black with high surface activity (large amount of hydrogen generated), heat generation is achieved. A rubber composition with significantly improved properties can be obtained. This rubber composition can be suitably used, for example, in the tread of a fuel-efficient tire.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between wear resistance and impact resilience in the SBR system.

Claims (1)

[Claims] An alkali metal and/or alkaline earth metal-added rubbery polymer and a ▲ mathematical formula, chemical formula, table, etc. ▼ bond (in the formula, X represents an O or S atom) in the molecule. benzophenones having an amino group and/or substituted amino group, thiobenzophenones having an amino group and/or substituted amino group, general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (in the formula, R is hydrogen Alternatively, an organic group may be an aminobenzene derivative represented by (n represents an integer of 1 to 4), an isocyanate compound, a monofunctional or difunctional active tin compound, a reactive compound having a thioether group, a carbodiimide, a Raw material rubber 10 containing at least 30% by weight of a polymer obtained by reacting with one or more compounds selected from carbon sulfide, xanthogen compounds, and dithioic acid compounds
Nitrogen adsorption specific surface area (N_2SA) is 7 parts by weight.
The amount of hydrogen generated at 5m^2/g or more and at 1300℃ (
A low heat build-up rubber composition, characterized in that it contains 20 to 150 parts by weight of carbon black, in which the relationship between the most frequent mode diameter (Dst, mμ) of aggregate distribution obtained by centrifugal sedimentation (H_2 amount) is expressed by the following formula: thing. H_2>3.74-0.02(Dst)