JP5044352B2 - Rubber additive and rubber composition - Google Patents

Description

  The present invention relates to an additive for rubber and a rubber composition using the same.

In response to social demands for energy saving in recent years, attempts have been made to reduce heat generation (that is, to reduce rolling resistance) of tire rubber for the purpose of saving fuel consumption of automobiles. In order to reduce the heat generation of rubber for tires, reduction of the amount of carbon black often used as a reinforcing filler for rubber, or the use of carbon black having a large particle size has been studied. However, in any case, it is known that the reinforcing property, the wear resistance, the grip property (driving stability) on the dry road surface and the wet road surface cannot be avoided.
On the other hand, hydrous silicic acid (wet silica) is known as a filler that achieves both low rolling resistance and steering stability on wet road surfaces (see, for example, Patent Documents 1 to 8). However, in this wet silica, particles tend to aggregate due to hydrogen bonds of silanol groups which are surface functional groups, and it is necessary to lengthen the kneading time in order to improve the dispersion of the silica in the rubber. Further, since the silica is not sufficiently dispersed in the rubber, the rubber composition has a high Mooney viscosity, and has disadvantages such as inferior processability such as extrusion. Furthermore, since the surface of the silica particles is acidic, the basic substance used as a vulcanization accelerator is adsorbed, the rubber composition is not sufficiently vulcanized, and the storage elastic modulus is not improved. Has the disadvantage that the steering stability is not sufficient.

As a method for improving the handling stability without impairing the fuel economy of the silica-containing rubber, a method of adding a resin (for example, see Patent Document 9 and Patent Document 10), a polymerizable unsaturated bond and a specific functional group are used. A rubber composition to which an added compound is added has been proposed (for example, Patent Document 11). However, this rubber composition has a problem of surface roughness of the vulcanized rubber due to insufficient compatibility between these resins and rubber, and an effect of improving the storage elastic modulus. There was a problem that the stability was not sufficiently improved.
On the other hand, it is known that the use of sulfur-containing polyesters can give mechanical properties and good hysteresis properties of vulcanized rubber (for example, Patent Document 12), but there is no description about storage elastic modulus. Absent. Further, a rubber composition using a compound having a reactive group for rubber and an adsorbing group for an inorganic filler such as silica in the same molecule as an additive for rubber has been proposed (for example, Patent Document 13). However, although this rubber composition shows a certain effect in improving the storage elastic modulus, development of a rubber additive that achieves both good operational stability on a dry road surface and excellent rolling resistance is desired. ing.

JP-A-3-252431 JP-A-6-248116 JP-A-7-70369 JP-A-7-188466 JP-A-7-196850 JP-A-8-225684 JP-A-8-245838 JP-A-8-337687 JP 2000-80205 A JP 2000-290433 A JP 2002-179841 A JP-A-8-333488 JP 2003-176378 A

  An object of the present invention is to provide a rubber additive capable of imparting good steering stability on a dry road surface and excellent rolling resistance to a tire, a rubber composition containing the rubber additive, and a member obtained from the rubber composition. The tire used as is to provide.

As a result of intensive studies to achieve the above object, the present inventors have found that the object can be achieved by a specific polyester compound. The present invention has been completed based on such findings.
That is, the present invention
(1) (A) The following general formula (1a):

[Wherein, R ¹ represents an alkanediyl group having 2 to 4 carbon atoms, and a plurality of R ¹ may be the same or different. m represents the number of 2-31 which shows an average addition mole number. ]
And (B) the following general formula (1b):

Wherein, R ² and R ³ represent alkanediyl group or an alkenediyl group having 1 to 9 carbon atoms, x is an integer of 2-8 showing the number of sulfur atoms. ]
A dicarboxylic acid monomer containing a sulfide group represented by the formula (A) is a polyester compound formed by polycondensation in such a manner that the molar amount of hydroxyl group of component (A) is larger than the molar amount of carboxyl group of component (B). Rubber additives,
(2) The polyester compound is a dicarboxylic acid monomer and / or (D) diol monomer other than the components (C) and (B), (A) and (D). The rubber according to (1) above, wherein the total molar amount of the component hydroxy groups is blended in an amount greater than the total molar amount of the carboxy groups of the component (B) and the component (C) and polycondensed. Additives for
(3) A rubber composition comprising (E) natural rubber and / or a diene synthetic rubber, (F) a filler, and the rubber additive according to (1) or (2) above,
(4) Further, (G) the rubber composition according to (3) above containing a silane coupling agent in a proportion of 1 to 20% by mass with respect to silica, and (5) the above (3) or (4) A tire using the rubber composition as a member,
Is to provide.

  According to the present invention, a rubber additive capable of imparting good steering stability to a tire on a dry road surface and excellent rolling resistance, a rubber composition containing the rubber additive, and the rubber composition as a member The tire used as can be obtained.

  The rubber additive of the present invention comprises (A) the following general formula (1a):

[Wherein, R ¹ represents an alkanediyl group having 2 to 4 carbon atoms, and a plurality of R ¹ may be the same or different. m represents the number of 2-31 which shows an average addition mole number. ]
And (B) the following general formula (1b):

Wherein, R ² and R ³ represent alkanediyl group or an alkenediyl group having 1 to 8 carbon atoms, x is an integer of 2-8 showing the number of sulfur atoms. ]
A dicarboxylic acid monomer containing a sulfide group represented by the formula (A) is a polyester compound formed by polycondensation in such a manner that the molar amount of the hydroxyl group of the component (A) is larger than the molar amount of the carboxy group of the component (B). To do.

[(A) component: polyoxyalkanediyl glycol]
The (A) polyoxyalkanediyl glycol used in the present invention is a compound represented by the following general formula (1a).

In the formula, R ¹ represents an alkanediyl group having 2 to 4 carbon atoms, and a plurality of R ¹ may be the same or different. For example, R ¹ O may be ethylene oxide alone or a combination of ethylene oxide and propylene oxide. Moreover, m is a number from 2 to 31 indicating an average added mole number, and preferably represents a number from 3 to 21.
Examples of such (A) polyoxyalkanediyl glycol include polyoxyethylene glycol, polyoxypropylene glycol, and the like, as well as ethylene glycol, propylene glycol, and butanediol, and polyoxyethylene, polyoxypropylene, polyoxytrimethylene. , And / or polyoxytetramethylene on average 1 to 30 mol, preferably 2 to 20 mol added.
(A) These polyoxyalkanediyl glycols can be used alone or in combination.

[(B) component: dicarboxylic acid monomer containing sulfide group]
The dicarboxylic acid monomer (B) containing a sulfide group used in the present invention is represented by the following general formula (1b).

Wherein, R ² and R ³ represents an alkanediyl group or an alkenediyl group having 1 to 9 carbon atoms. X is an integer of 2 to 8 indicating the number of sulfur atoms, preferably 2 to 4 and more preferably 2 from the viewpoint of suppressing gelation of the polymer in the kneading operation in the preparation of the rubber composition.
Examples of the dicarboxylic acid monomer containing such a sulfide group include 2,2′-dithiodiacetic acid, 3,3′-dithiodipropionic acid, 4,4′-dithiodibutanoic acid, 5,5′-dithiodipentanoic acid, Preferred examples include 6,6′-dithiodihexanoic acid, 7,7′-dithiodiheptanoic acid, 8,8′-dithiodioctanoic acid, 9,9′-dithiodinonanoic acid, and 10,10′-dithiodidecanoic acid. Of these, 3,3′-dithiodipropionic acid is more preferable.

[(C) component: other dicarboxylic acid monomer]
The polyester compound according to the present invention may be polycondensed by blending the (A) component and the (B) component with a dicarboxylic acid monomer and / or (D) diol monomer other than the (C) and (B) components, if desired. It may be made.
(C) The dicarboxylic acid monomer other than the component (B) can be used without particular limitation as long as it is a dicarboxylic acid monomer other than the component (B). For example, diacetic acid, dipropionic acid, dibutanoic acid, dipentanoic acid, Saturated dicarboxylic acids such as dihexanoic acid, diheptanoic acid, dioctanoic acid, dinonanoic acid, and didecanoic acid; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, citraconic acid; aromatic dicarboxylic acids such as phthalic acid, etc. be able to.
1-20 mol% is preferable and, as for content of (C) component in a polyester compound, 1-10 mol% is preferable.

[(D) component: diol monomer]
(D) Although it can use without a restriction | limiting especially as a diol monomer, What is represented by following General formula (2) is mentioned preferably.

In the formula, R ⁷ represents an alkanediyl group or alkenediyl group having 2 to 18 carbon atoms.
Examples of the diol monomer (A) include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, and other alkanediols; ethylenediol, propylenediol, butenediol. Alkendiols such as are preferred.
1-20 mol% is preferable and, as for content of (D) component in a polyester compound, 1-10 mol% is preferable.

[Polyester compound]
The polyester compound according to the present invention includes (A) a polyoxyalkanediyl glycol and (B) a dicarboxylic acid monomer as described above, and (C) a dicarboxylic acid monomer other than the component (B) blended as desired. / Or (D) A diol monomer is polycondensed. Here, the molar amount of hydroxyl group in component (A) (hereinafter referred to as A molar amount) is polycondensed in an amount greater than the molar amount of carboxyl group in component (B) (hereinafter referred to as B molar amount). Cost. Further, when the component (C) and the component (D) are further blended, the above A molar amount is the total molar amount of the hydroxyl groups of the (A) component and the (D) component, and the above B molar amount is ( Let B be the total molar amount of the carboxyl groups of component (C).
The A molar amount is not particularly limited as long as it is larger than the B molar amount, but it is preferable to blend so that the weight fraction of sulfur atoms in the polyester compound described below is within a predetermined range. The ratio between the A mole amount and the B mole amount is not generally determined because it varies depending on the amount of sulfur atoms contained in the component (B) and the number average molecular weight of the desired polyester compound. The molar amount of / B is about 1.01 / 1 to 3/1, preferably 1.01 / 1 to 2/1.
The mass fraction of sulfur atoms in the polyester compound is preferably more than 5%, more preferably more than 5% to 45%, and still more preferably 10 to 30% from the viewpoint of improving steering stability.

The number average molecular weight of the polyester compound is preferably 1000 or more, more preferably 1000 to 10000, and still more preferably 1000 to 7000. If it exists in this range, since a storage elastic modulus will improve, favorable steering stability will be acquired. Here, the number average molecular weight of the polyester compound is a value measured using gel permeation chromatography (GPC) (polystyrene conversion). As the column, G2000HXL and G1000HXL (both manufactured by Tosoh Corporation) were connected in series. The developing solvent was tetrahydrofuran (THF), and the sample / solvent was 0.04 g / 10 ml.
The average polymerization number of the polyester compound is preferably from 0.8 to 100, more preferably from 5 to 100, and even more preferably from 8 to 100, from the viewpoints of storage elastic modulus (steering stability) and rolling resistance. Here, the average polymerization number of the polyester compound is obtained by subtracting the molecular weight of the terminal portion not corresponding to the repeating unit from the number average molecular weight Mn obtained using gel permeation chromatography (GPC), and dividing by the unit molecular weight of the repeating unit. It is the value.

  The method of polycondensation of (A) diol monomer and (B) dicarboxylic acid monomer is not particularly limited, and is a method of directly esterifying diol monomer and dicarboxylic acid monomer, or ester of diol monomer and alkyl ester of dicarboxylic acid. The method of exchange etc. are mentioned. The polycondensation is preferably performed at a temperature of 60 to 150 ° C. by removing water, and a solvent such as cyclohexane, benzene, toluene and / or xylene can be used as necessary. Moreover, in the said polycondensation, it is preferable to use the catalyst generally used for the above methods, for example, p-toluenesulfonic acid, methanesulfonic acid etc., for the purpose of promoting polycondensation.

  Among the polyester compounds thus obtained, those having as a main component those represented by the following general formula (3) are preferred. 50-99 mass% is preferable, as for content of the compound represented by General formula (3) in a polyester compound, 70-99 mass% is more preferable, and 80-99 mass% is further more preferable.

In the formula, R ⁴ represents an alkanediyl group having 2 to ⁴ carbon atoms, R ⁵ and R ⁶ represent an alkanediyl group having 2 to 8 carbon atoms, and a plurality of R ⁴ , R ⁵ and R ⁶ are the same or different. May be. For example, R ⁴ O may be ethylene oxide alone or a combination of ethylene oxide and propylene oxide.
y is an integer of 2 to 4 indicating the number of sulfur atoms, and 2 is more preferable. n is a number from 2 to 100 indicating the average number of polymerizations, and the preferred range is the same as the average number of polymerizations described above. M is the same as described above.

[Rubber composition]
The rubber composition of the present invention comprises (E) natural rubber and / or a diene synthetic rubber, (F) a filler, and the above-mentioned rubber additive.
The rubber additive is preferably contained in a proportion of 0.5 to 20% by mass, more preferably 1 to 15% by mass, and further preferably 2 to 10% by mass with respect to the component (F). If the content of the rubber additive is within the above range, the effect of blending the additive is sufficiently exerted, and the effect corresponding to the blending amount is improved, which is economically advantageous.

[Rubber composition: (E) natural rubber and / or diene synthetic rubber]
Examples of the diene synthetic rubber include polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). It is done. The natural rubber or diene synthetic rubber of component (E) may be used alone or in combination of two or more.

[Rubber composition: (F) Filler]
The rubber composition of the present invention contains (F) a filler.
Examples of (F) fillers usually include carbon black and silica, and those containing these are preferred. Carbon black is a known carbon black in which ranges such as I ₂ adsorption amount, CTAB specific surface area, N ₂ adsorption amount, DBP adsorption amount are appropriately selected as long as it improves mechanical performance and improves processability. Can be used. As the type of carbon black, for example, known ones such as SAF, ISAF-LS, HAF, HAF-HS can be appropriately selected and used. In view of wear resistance, ISAF or SAF having a fine particle size is preferable.
Silica does not represent only silicon dioxide in a narrow sense, but means a silicate-based filler. Specifically, in addition to anhydrous silicic acid, hydrous silicate, calcium silicate, aluminum silicate, etc. Contains silicates.

(F) One or more fillers may be used in combination, but it is preferable to use a combination of the above-described carbon black and silica.
Moreover, the content of the filler (F) in the composition of the present invention is preferably in the range of 10 to 140 parts by mass per 100 parts by mass of the component (E). By setting the content to 10 to 140 parts by mass, the object of the present invention can be achieved without adversely affecting the reinforcing properties and other rubber physical properties. As for content of this (F) component, 10-90 mass parts is more preferable. When (F) carbon black and silica are used in combination as a filler, the mixing ratio [carbon black] / [silica] of carbon black and silica is preferably 0.04 to 6.0 in terms of mass ratio, 0.1-2.0 are more preferable and 0.1-1.0 are more preferable.

[Rubber composition: (G) Silane coupling agent]
In the rubber composition of the present invention, it is preferable to further contain (G) a silane coupling agent for the purpose of further improving the effects of the present invention. (G) As the silane coupling agent, any of the conventionally known silane coupling agents can be used, and among them, general formula (4a):

[In the formula, A is an alkoxy group having 1 to 3 carbon atoms or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, X is an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms, or 7 to 15 carbon atoms. An arylene group, a is an integer of 1 to 3, and b is an integer of 1 or more and may have a distribution. However, when a is 1, two B may be the same or different, and when a is 2 or 3, two or three A may be the same or different. ]
A compound represented by the general formula (4b):

[Wherein, A, B, X and a are the same as above, Y is a mercapto group, vinyl group, amino group, glycidoxy group or epoxy group]
A compound represented by the general formula (4c):

[Wherein, A, B, X, a and b are the same as above, Z is a benzothiazolyl group, N, N-dimethylthiocarbamoyl group or methacryloyl group, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms]
And a compound represented by the general formula (4d):

[Wherein, A, B and X are the same as above, and X ¹ is a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, or an arenediyl group having 6 to 15 carbon atoms. D is A, B, or — [O (XO) _n ] _0.5 — group, n may be an integer of 1 to 4 and may have a distribution, and X is the same as described above. C, d, and e are numbers satisfying the relationship of 0 ≦ c ≦ 3, 0 ≦ d ≦ 2, 0 ≦ e ≦ 1, and c + d + 2e = 3. ]
It is preferable that it is at least 1 sort (s) chosen from the compound represented by these.

  Examples of the silane coupling agent represented by the general formula (4a) include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (3-methyldimethoxysilylpropyl). ) Tetrasulfide, bis (3-triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, etc. However, examples of the silane coupling agent represented by the general formula (4b) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and 3-aminopropyl. Trier Xylsilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and the like are represented by the general formula (4c). Examples of silane coupling agents include 3-trimethoxysilylpropyl-N, N-dimethylcarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-trimethoxysilylpropylmethacryloyl monosulfide, 3- Triethoxysilylpropyl n-octyl disulfide and the like, and examples of the silane coupling agent represented by the general formula (4d) include 3-octanoylthiopropyltriethoxysilane and the like.

  Such (G) silane coupling agents may be used alone or in combination of two or more. Moreover, 1-20 mass% is preferable with respect to (F) filler, and, as for content of (G) component in a rubber composition, 3-15 mass% is more preferable. If content of (G) component exists in said range, since the effect which mix | blended the silane coupling agent will fully be exhibited and the improvement corresponding to a compounding quantity will be seen, it is economically advantageous.

[Rubber composition: inorganic compound powder]
The rubber composition of the present invention can contain inorganic compound powder as necessary. Here, the inorganic compound powder is preferably a compound represented by the following general formula (5).

Here, in the formula, 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 these metals. And f, g, h and i 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.
In the general formula (5), when g and h are both 0, the inorganic compound powder is at least one metal selected from aluminum, magnesium, titanium, calcium and zirconium, metal oxide or metal water. It becomes an oxide.

As the inorganic compound powder represented by the general formula (5), M ¹ is at least one selected from aluminum metal, aluminum oxide or hydroxide, and hydrates thereof, or aluminum carbonate. Some cases are preferred.
These inorganic compound powders represented by the general formula (5) may be used alone or in combination of two or more.
Moreover, it is preferable that the inorganic compound powder in this invention is a powder with the particle size of 0.01-10 micrometers. If the particle size is less than 0.01 μm, the kneading operation is deteriorated while the improvement of the grip force cannot be expected, and if it exceeds 10 μm, the storage elastic modulus is extremely lowered and the wear resistance is deteriorated. In view of these effects, the particle size is more preferably in the range of 0.05 to 5 μm.

  In the composition of the present invention, the content of the inorganic compound powder is preferably in the range of 10 to 140 parts by mass and more preferably 20 to 90 parts by mass per 100 parts by mass of the component (E).

  In the rubber composition of the present invention, various compounding agents usually used in the rubber industry, for example, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, and an anti-scorch agent are used, as desired, as long as the object of the present invention is not impaired Agents, softeners, zinc white, stearic acid, and the like.

The method for adding the rubber additive, (F) filler, (G) silane coupling agent, and various compounding agents to the rubber composition in the present invention is not particularly limited. (E) Natural rubber and / or diene The system synthetic rubber can be added and mixed using an ordinary kneading machine such as a Banbury mixer, a roll, or an intensive mixer.
The rubber composition of the present invention thus obtained can be used as a tire member, and the member is particularly preferably used for a tread or a tread base. A pneumatic tire is manufactured by a normal method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into, for example, a tread member at an unvulcanized stage and pasted on a tire molding machine by a usual method. The green tire is formed by attaching. The green tire is heated and pressed in a vulcanizer to obtain a tire.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
(Evaluation method)
(1) Dynamic viscoelasticity About the rubber composition obtained in each Example and Comparative Example, using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Ueshima Seisakusho Co., Ltd., frequency 52 Hz, initial distortion 2 %, Dynamic strain rate of 1%, storage elastic modulus (E ′) at 60 ° C., and tan δ were measured and shown in Tables 2 to 6 as indices with Comparative Examples 1 and 4 to 7 as 100. It was. A larger index of storage elastic modulus (E ′) indicates better rubber physical properties, and a smaller index of tan δ indicates lower exothermic properties.
(2) Rolling resistance A pneumatic tire having a tire size of 225 / 45R17 was made as a trial with a tread having a single-layer structure, using the rubber compositions having the compounding formulations shown in Tables 2 to 6 as tread members.
The tire resistance of the prototype was 250 kPa, and the rolling resistance when rotating at a speed of 80 km / h using a rotating drum with a diameter of 1700 mm under the action of a load of 3.92 kN was measured by the coasting method. The index is shown in Tables 2 to 6 as 1, 4 to 7 as 100. The larger the rolling resistance index, the smaller and better the rolling resistance.
(3) Steering stability on dry road surface A pneumatic tire having a tire size of 225 / 45R17 was made as a trial with a tread having a single layer structure, using the rubber composition of the formulation shown in Tables 2 to 6 as a tread member.
The air pressure of the prototype tire was set to 250 kPa, and the tire was mounted on four wheels of a passenger car. A test driver ran on the test course in this test vehicle. Regarding the feeling results on the driving stability and riding comfort of each tire by the test driver, the results of scoring according to the following evaluation criteria in comparison with the control tires (Comparative Examples 1, 4 to 7) The results are shown in Table 2 to Table 6.
+4: When a driver feels good enough to understand a general driver +3: When a driver feels good enough to understand a skilled driver +2: When a driver feels good enough to clearly understand a test driver +1: A test driver is subtly When it feels good enough to understand -1: When it feels bad enough to understand the test driver -2: When it feels bad enough to understand the test driver -3: To the extent that a skilled driver can understand among general drivers -4: If you feel bad enough to understand a general driver

Production Example 1: Production of polycondensate In a 1 L four-necked flask, 285 g (1.14 mol) of polytetramethylene glycol (number average molecular weight: 250, hereinafter referred to as PTMG250) and dithiodipropionic acid (hereinafter referred to as DTDPA). 217.9 g (1.04 mol) was charged, 0.1% by mass of p-toluenesulfonic acid of the obtained mixture was added, and the mixture was stirred at 140 ° C. for 12 hours under a nitrogen stream, and produced by reaction. After removing the water, 449 g of pale yellow viscous oil was obtained. The average degree of polymerization of the viscous oil was 9.3.

Production Examples 2-5
Each component shown in Table 1 was mixed at the blending ratio shown in Table 1, and polycondensation was performed in the same manner as in Production Example 1 to obtain a polycondensate (polyester compound).

Examples 1-8, Comparative Examples 1-7
The components shown in Tables 2 to 6 were mixed at the blending ratios shown in Tables 2 to 6 to prepare rubber compositions. A Banbury mixer and a roll mixer were used for the preparation. Vulcanization was carried out at a temperature of 165 ° C., and the vulcanization time was defined as Curast T90 value (min) × 1.5 times. Using the obtained rubber composition, a pneumatic tire having a tire size of 225 / 45R17 was made as a trial with a tread having a single-layer structure.
About these rubber compositions, the dynamic viscoelasticity measurement test was evaluated as an index of vulcanized rubber physical properties. The results are shown in Tables 2-6. In the dynamic viscoelasticity measurement test, indexes were displayed based on Comparative Examples 1 and 4 to 7. Moreover, about the obtained tire, rolling resistance and steering stability were evaluated as a tire performance parameter | index. The results are shown in Tables 2-6.

* 1, PTMG250: Polytetramethylene glycol (Sigma Aldrich, number average molecular weight 250)
* 2, DTDPA: Dithiodipropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)

* 1, “SBR # 1712 (trade name)”: 37.5 parts by mass is oil-extended in 137.5 parts by mass of SBR # 1712 manufactured by JSR Corporation.
* 2, "Seast 300 (trade name)": manufactured by Tokai Carbon Co., Ltd. * 3, "Nip seal VN3 (trade name)": manufactured by Tosoh Silica Co., Ltd. * 4, bis (3-triethoxysilylpropyl) tetrasulfide * 5, trimellitic acid mono (ω-acryloyloxy POE (10)) ester, POE (10) represents polyoxyethylene added with 10 mol of oxyethylene.
* 6, N-oxydiethylene-2-benzothiazolesulfenamide * 7, diphenylguanine * 8, N- (1,3-dimethylbutyl) -N'-phenyl-phenylenediamine

* 9, “Seast 7HM (trade name)”: manufactured by Tokai Carbon Co., Ltd. * 10, “Nip seal AQ (trade name)”: manufactured by Tosoh Silica Co., Ltd. * 11, “Si75 (trade name)”: manufactured by degussa * 12 , "Sunseller DM (trademark)": Sanshin Chemical Industry Co., Ltd. * 13, "Suncellor NS (trademark)": Sanshin Chemical Industry Co., Ltd. * 14, "Noxeller D (trademark)": Ouchi Shinsei Chemical Industry * 15, "NOCRACK 6C (trademark)" manufactured by Ouchi Shinsei Chemical Co., Ltd.

* 16, "SBR # 1500 (trade name)": JSR Corporation * 17, "Seast KH (trade name)": Tokai Carbon Co., Ltd. * 18, "Nip seal KQ (trade name)": Tosoh Silica Corporation * 19, “NTX Silane (trademark)” manufactured by Momentive Performance Materials

  The rubber additive of the present invention can impart good steering stability on a dry road surface and excellent rolling resistance to a tire. The rubber composition using the rubber additive is suitable for use as a tire tread or a tread base member.

Claims (13)

(A) The following general formula (1a):

[Wherein, R ¹ represents an alkanediyl group having 2 to 4 carbon atoms, and a plurality of R ¹ may be the same or different. m represents the number of 2-31 which shows an average addition mole number. ]
And (B) the following general formula (1b):

Wherein, R ² and R ³ represent alkanediyl group or an alkenediyl group having 1 to 9 carbon atoms, x is an integer of 2-8 showing the number of sulfur atoms. ]
A dicarboxylic acid monomer containing a sulfide group represented by the formula (A) is a polyester compound formed by polycondensation in such a manner that the molar amount of the hydroxyl group of the component (A) is larger than the molar amount of the carboxy group of the component (B). Additive for rubber.   The polyester compound further comprises (C) component (B), dicarboxylic acid monomer and / or (D) diol monomer other than component (C) and component (B), hydroxy component (A) and component (D). The rubber additive according to claim 1, wherein the total molar amount of the groups is blended in an amount larger than the total molar amount of the carboxy groups of the component (B) and the component (C) and polycondensed.   The rubber additive according to claim 1 or 2, wherein x is 2 in the general formula (1b).   The rubber additive according to any one of claims 1 to 3, wherein the polyester compound has a number average molecular weight of 1000 or more. The polyester compound has the following general formula (3):

[Wherein R ⁴ represents an alkanediyl group having 2 to ⁴ carbon atoms, R ⁵ and R ⁶ represent an alkanediyl group having 2 to 8 carbon atoms, and a plurality of R ⁴ , R ⁵ and R ⁶ are the same or different. It may be. y is an integer of 2 to 4 indicating the number of sulfur atoms, and n is a number of 0.8 to 100 indicating the average polymerization number. M is the same as described above. ]
The additive for rubber | gum in any one of Claims 1-4 containing what is represented by these as a main component.   A rubber composition comprising (E) natural rubber and / or a diene synthetic rubber, (F) a filler, and the rubber additive according to any one of claims 1 to 5.   The rubber composition according to claim 6, comprising a rubber additive in a proportion of 0.5 to 20% by mass relative to the component (F).   The rubber composition according to claim 6 or 7, comprising 10 to 140 parts by mass of (F) component per 100 parts by mass of (E) component.   The rubber composition according to any one of claims 6 to 8, wherein (F) the filler contains silica.   Furthermore, the rubber composition in any one of Claim 9 which contains (G) silane coupling agent in the ratio of 1-20 mass% with respect to a silica. (G) The silane coupling agent has the following chemical formula (4a):

[In the formula, A is an alkoxy group having 1 to 3 carbon atoms or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, X is an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms, or 7 to 15 carbon atoms. An arylene group, a is an integer of 1 to 3, and b is an integer of 1 or more and may have a distribution. However, when a is 1, two B may be the same or different, and when a is 2 or 3, two or three A may be the same or different. ]
A compound represented by the general formula (4b):

[Wherein, A, B, X and a are the same as above, Y is a mercapto group, vinyl group, amino group, glycidoxy group or epoxy group]
A compound represented by the general formula (4c):

[Wherein, A, B, X, a and b are the same as above, Z is a benzothiazolyl group, N, N-dimethylthiocarbamoyl group or methacryloyl group, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms]
And a compound represented by the general formula (4d):

[Wherein, A 1, B and X are the same as above, and X ¹ is a saturated or unsaturated alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. D is A, B, or — [O (XO) _n ] _0.5 — group, n may be an integer of 1 to 4 and may have a distribution, and X is the same as described above. C, d, and e are numbers satisfying the relationship of 0 ≦ c ≦ 3, 0 ≦ d ≦ 2, 0 ≦ e ≦ 1, and c + d + 2e = 3. ]
The rubber composition according to claim 10, which is at least one selected from the compounds represented by:   A tire using the rubber composition according to any one of claims 6 to 11 as a member.   The tire according to claim 12, wherein the member is a tread and / or a tread base.