JP2002121330A - Additive for rubber composition, additive composition for rubber composition, rubber composition using the same, and pneumatic tire - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the processability while maintaining the physical properties of rubber and without any problems in the working environment. To provide an improved rubber composition additive, a rubber composition additive composition, a rubber composition using the same, and a pneumatic tire which are stable and free from problems. SOLUTION: An additive for a rubber composition, which is an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative, having at least one carboxyl group bonded to an aromatic ring in the molecule, and reinforcement Ionic filler (a),
And the above-mentioned ester (b), and the weight ratio (a) / (b) of the component (a) to the component (b) is 70 /
An additive composition for a rubber composition having a ratio of 30 to 30/70, a rubber composition obtained by blending them with a rubber component, and a pneumatic tire using the rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an unvulcanized rubber composition and a vulcanized rubber composition without adversely affecting the physical properties of the composition.
The present invention relates to an additive for a rubber composition, an additive composition for a rubber composition, a rubber composition using the same, and a pneumatic tire that can improve processability and productivity in the production of rubber products.

[0002]

2. Description of the Related Art In general, rubber products such as tires, belts and hoses are kneaded to uniformly disperse compounding agents and fillers in raw rubber. For ease, several milling steps to further plasticize the unvulcanized rubber composition may be required. However, performing such plasticizing operations many times is not preferable in terms of productivity of rubber products. On the other hand, in order to improve the productivity of rubber products, it is effective to reduce the number of kneading, but even if the number of kneading is simply reduced, the unvulcanized rubber composition is not sufficiently plasticized. It does not lead to improved sex.

[0003] Therefore, by adding a plasticizer or a processing aid, the processability of the unvulcanized rubber composition is improved,
Although it is possible to reduce the number of kneading and improve the molding workability, it is possible to reduce the physical properties of the unvulcanized rubber composition or the vulcanized rubber composition by using a conventional plasticizer or processing aid. Therefore, it was practically difficult to reduce the number of kneading. In particular, in the processing step in the production of conventional rubber products containing natural rubber, the entanglement of the natural rubber molecular chains and the functional groups in the natural rubber isoprene chain or such functional groups and non-rubber components in the natural rubber The presence of a polymer gel due to the above reaction required the number of kneadings to be increased, and the productivity was not satisfactory. Also, if the number of kneading is increased to plasticize the unvulcanized rubber composition,
A decrease in the molecular weight of the natural rubber molecules occurs, which adversely affects the physical properties of the vulcanized rubber composition. Therefore, conventionally, there has been a demand for improving the molding workability without deteriorating the physical properties of the unvulcanized rubber composition and the vulcanized rubber composition, particularly in the production of rubber products containing natural rubber.

On the other hand, several proposals have recently been made to solve these problems. For example, JP
JP-A-209406 describes that an aromatic polycarboxylic acid derivative is added to natural rubber to reduce the amount of polymer gel of the natural rubber. However, in this method, it was found that bloom was easily generated after vulcanization. Also, JP-A-6-57040 and JP-A-Hei-4
JP-A-20579 also added a specific ester,
Although it is described that the processability is improved, these methods generate a peculiar smell during the process and have a problem in the working environment.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention has been made to solve the above-mentioned problems.
An improved rubber composition additive capable of improving processability without deteriorating the physical properties of the rubber composition and problems in the working environment and stabilizing the surface state of unvulcanized and vulcanized rubber compositions. It is an object of the present invention to provide a rubber composition additive composition, a rubber composition using the same, and a pneumatic tire.

[0006]

Means for Solving the Problems The present inventors utilize a partial ester of a specific aromatic polycarboxylic acid and a (poly) oxyalkylene derivative as an additive for a rubber composition to obtain a vulcanized rubber. Without impairing the physical properties of the composition,
The present inventors have found that slip between rubber molecules increases, and found that this achieves the above-mentioned object, and have completed the present invention. That is, the present invention provides an additive for a rubber composition, which is an ester of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in a molecule. The agent is provided. The present invention also provides a reinforcing filler (a)
And an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule, wherein (b) of the component (a) )) Weight ratio to component (a) /
(B) is 70/30 to 30/70, which provides an additive composition for a rubber composition.

Further, the present invention relates to an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule in the rubber component (A). ) And an aromatic polycarboxylic acid and (poly) oxy having at least one carboxyl group bonded to an aromatic ring in the molecule in the rubber component (A). An object of the present invention is to provide a rubber composition characterized by comprising an additive composition (B) for a rubber composition comprising an ester (b) with an alkylene derivative and a reinforcing filler (a). The present invention also provides a pneumatic tire using the above rubber composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition additive of the present invention comprises:
An ester of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule. This ester is
Those represented by the following general formula (I) are preferred.

[0009]

Embedded image [In the formula (I), m represents an average degree of polymerization and is a number of 1 or more, n and p are integers of 1 or more, q is 0 or an integer of 1 or more, and n + p + q is 6 to 8. A is an aromatic ring, R ¹ is an alkylene group, R ² is an alkyl group, an alkenyl group, an alkylaryl group or an acyl group, and R ³ is a hydrogen, an alkyl group or an alkenyl group. ]

In the general formula (I), more preferably, n + p is 2 or 3, R ¹ is an alkylene group having 2 to 4 carbon atoms, R ² is an alkyl group or alkenyl group having 2 to 28 carbon atoms, More preferably, A is a benzene ring, and n =
1, p = 1, R ¹ is an ethylene group, R ² is a carbon number of 2 to 28
Most preferably m is 1 to 10, n = 1, p = 1, R ¹ is an ethylene group, R
² is an alkyl or alkenyl group having 8 to 18 carbon atoms.

The rubber composition additive of the present invention comprises:
It is obtained by reacting (i) a divalent or higher valent aromatic carboxylic acid or an anhydride thereof with (ii) a (poly) oxyalkylene derivative. Here, (i) the divalent or higher valent aromatic carboxylic acid includes, for example, phthalic acid, phthalic anhydride,
Divalent aromatic carboxylic acids such as naphthalenedicarboxylic acid and their anhydrides, trivalent aromatic carboxylic acids such as trimellitic acid and trimellitic anhydride and their anhydrides, pyromellitic acid, pyromellitic anhydride, etc. And tetravalent aromatic carboxylic acids and their anhydrides,
From the viewpoint of cost, divalent or trivalent aromatic carboxylic acids or anhydrides thereof are preferable, and phthalic anhydride is particularly preferable.

The (ii) (poly) oxyalkylene derivative is, for example, a compound having a (poly) oxyalkylene group having one or more hydroxyl groups and having an average degree of polymerization of 1 or more. A compound having a (poly) oxyalkylene group having 2 to 2 hydroxyl groups,
Particularly preferred is a compound having a (poly) oxyalkylene group having one hydroxyl group. Examples of the (poly) oxyalkylene derivative include ether types such as (poly) oxyalkylene alkyl ether; ester types such as (poly) oxyalkylene fatty acid monoester; ether ester types such as (poly) oxyalkylene glycerin fatty acid ester; ) Oxyalkylene fatty acid amides, nitrogen-containing types such as (poly) oxyalkylenealkylamines, etc.
As the oxyalkylene derivative, an ether type and an ester type are preferable, and an ether type is particularly preferable.

The ether type (poly) oxyalkylene derivatives include polyoxyethylene lauryl ether, polyoxyethylene decyl ether, polyoxyethylene octyl ether, polyoxyethylene 2-ethylhexyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene lauryl ether, Oxypropylene stearyl ether, polyoxyalkylene such as polyoxyethylene oleyl ether, polyoxyalkylene aliphatic ether containing unsaturation, polyoxyethylene benzyl ether, polyoxyethylene alkyl phenyl ether,
Examples thereof include polyoxyethylene aromatic ethers such as polyoxyethylene benzylated phenyl ether, and polyoxyalkylene aliphatic ethers are preferred.
Further, polyoxyethylene alkyl or alkenyl ether is preferable, and particularly preferably, the average degree of polymerization of polyoxyethylene is 1 to 10, and the alkyl group or alkenyl group has 8 to 18 carbon atoms. Specifically, if polyoxyethylene is abbreviated as POE (n) and n is the average degree of polymerization, POE (3) octyl ether, POE (3)
(4) 2-ethylhexyl ether, POE (3) decyl ether, POE (5) decyl ether, POE
(3) Lauryl ether, POE (8) lauryl ether, POE (1) stearyl ether and the like.

Next, the additive composition for a rubber composition of the present invention comprises a reinforcing filler (a) and an aromatic polycarboxylic acid having at least one carboxyl group bonded to an aromatic ring in the molecule. And the ester (b) of a (poly) oxyalkylene derivative and the weight ratio (a) / (b) of the component (a) to the component (b) is 100
It is preferably from 0/30 to 30/70. If the weight ratio of component (a) is less than 30, handling may be difficult, and if the weight ratio of component (a) exceeds 70, workability may not be sufficiently improved. From this point, (a) / (b) is also 60/40 to 40/60.
(Weight mixing ratio) is preferable. The reinforcing filler (a) is not particularly limited, but is preferably an inorganic filler such as carbon black, silica, talc, clay, or aluminum hydroxide. Particularly, carbon black, silica or aluminum hydroxide is preferred. preferable. Among them, preferably, the carbon black is HAF, IS
Examples of the silica include AF and SAF. Examples of the silica include those having an N ₂ SA (nitrogen adsorption specific surface area) of 50 to 250 m ² / g and a DBP (dibutyl phthalate oil absorption) of 150 to 300 ml / 100 g.

The additive composition for a rubber composition further comprises (c) a (poly) oxyalkylene derivative,
It can contain at least one selected from alcohols and fatty acid esters thereof. The compounding amount is preferably 10 parts by weight or less based on 100 parts by weight of the total of the components (a) and (b). The melting point of the component (c) is 20 ° C.
Or less, and the boiling point is preferably 150 ° C. or higher. The melting point of the component (c) is preferably 20 ° C. or less from the viewpoint of suppressing dust in the production of the rubber composition additive composition or the rubber composition, and the boiling point is 150 ° C. from the viewpoint of safety during processing of the rubber composition. It is preferable that it is above.

Here, the (poly) oxyalkylene derivative as the component (c) is the same as the (poly) oxyalkylene derivative of the above (ii), and includes ether type, ester type, ether ester type and nitrogen-containing type. Preferred are ether-type and ester-type polyoxyalkylene derivatives. The alcohol as the component (c) is not particularly limited, but is preferably an aliphatic alcohol having 8 to 20 carbon atoms, such as octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, lauryl alcohol, and the like. Oleyl alcohol, stearyl alcohol, ethylene glycol, caprylic alcohol, and the like are included. In addition, fatty acid esters of these alcohols are preferably used.

Among the above components (c) used in the present invention, ether-type or ester-type polyoxyethylene derivatives or ethylene glycol fatty acid esters are particularly preferable. Specifically, polyoxyethylene is POE
(N), where n is the average degree of polymerization, POE
(3) Lauryl ether, POE (5) decyl ether, POE (4) oleyl ether, POE (10) monolaurate, POE (10) monooleate, ethylene glycol dioleate, POE (9) dicaprylate and the like. In order to obtain the above-mentioned additive composition for a rubber composition, the respective components may be mixed using a mixer, for example, a Henschel mixer, a Nauta mixer,
A tumbler mixer and the like are mentioned, and an optimum range such as a rotation speed, a stirring temperature, and a stirring time is selected for each mixer.

Furthermore, the first rubber composition according to the present invention is characterized in that the rubber component (A) comprises an aromatic polycarboxylic acid and (poly) oxy having at least one carboxyl group bonded to an aromatic ring in the molecule. It is obtained by blending an ester (b) with an alkylene derivative, and can be used in combination with a reinforcing filler (a). Further, it is preferable that at least one selected from (poly) oxyalkylene derivatives, alcohols and fatty acid esters thereof is further blended as the component (c). The component (c) has a melting point of 20 ° C. or less and a boiling point of 15 for the same reason as described above.
The temperature is preferably 0 ° C. or higher. Further, the second rubber composition according to the present invention, the rubber component (A) has at least one carboxyl group bonded to an aromatic ring in the molecule,
It can be obtained by blending the rubber composition additive composition (B) comprising an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative and a reinforcing filler (a). Further, it is preferable that at least one selected from (poly) oxyalkylene derivatives, alcohols and fatty acid esters thereof is further blended as the component (c). This component (c) has a melting point of 20 ° C. or less and a boiling point of 15 ° C. for the same reason as described above.
The temperature is preferably 0 ° C. or higher. In the above, the reinforcing filler (a) is not particularly limited as described above, but carbon black, silica and aluminum hydroxide are preferable, and the compounding amount is 10 to 85 parts by weight with respect to 100 parts by weight of the rubber component. Parts by weight are preferred. Here, the compounding amount of the reinforcing filler (a) in the rubber composition additive composition (B) is 70/30 to 30/70 as a weight ratio (a) / (b) to the component (b). Preferably, there is. The amount of the component (c) is preferably 10 parts by weight or less based on 100 parts by weight of the total amount of the components (a) and (b). Further, the compounding amount of the component (b) in the rubber composition of the present invention is based on 100 parts by weight of the rubber component.
It is preferably 0.1 to 10 parts by weight. When the content is 0.1 part by weight or more, the processability is improved, and when the content is 10 parts by weight or less, the rubber properties are maintained and it is desirable from the viewpoint of cost. In this respect, the content is more preferably 0.5 to 5 parts by weight. These components may be mixed, for example, by kneading. The same applies to the case where the component (b) is blended as the rubber composition additive composition (B). In this case, the amount of the component (b) is reduced to 100 parts by weight of the rubber component. It is preferably blended so as to be 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight.

When the rubber component (A) contains natural rubber, the rubber composition of the present invention can reduce the amount of polymer gel of natural rubber without lowering the molecular weight of natural rubber molecules. By increasing the slip between molecules, the molding workability is improved, and the deterioration of the properties of the unvulcanized or vulcanized rubber composition is suppressed. Further, when the rubber component (A) does not contain natural rubber, the molding workability is improved by increasing the slip between rubber molecules. In this case, too, since the molecular weight of the rubber does not decrease, the rubber component is not added. No deterioration in the properties of the vulcanized or vulcanized rubber composition occurs. In any case, in the present invention, excellent rubber processability can be obtained without adversely affecting rubber properties. The type of the rubber component (A) used in the rubber composition of the present invention is not particularly limited, but natural rubber alone or a blend rubber of natural rubber and synthetic rubber is preferable. Examples of the synthetic rubber to be blended include styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), and butyl rubber (I
IR), halogenated butyl rubber (X-IIR), ethylene propylene rubber (EPDM), and the like, and mixtures thereof.

Further, the reinforcing filler used in the rubber composition of the present invention, besides the reinforcing filler (a) used as the above-mentioned additive composition for rubber composition, is usually used in the rubber industry. Fillers such as HA
Carbon black such as F, ISAF, SAF, silica,
A white filler such as aluminum hydroxide, clay and talc can be blended. These may be used alone or in combination of two or more. Further, the rubber composition of the present invention,
If necessary, other rubber compounding agents, for example, sulfur, vulcanization accelerator, process oil, antioxidant and the like can be appropriately compounded. The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll or an internal mixer, and after molding, vulcanization is performed to obtain a tire tread, an undertread, a carcass, a sidewall, and a bead. It can be used for rubber tires, belts, hoses and other industrial products, including tires for parts, etc., but is particularly preferably used as rubber for tire treads. The pneumatic tire of the present invention is manufactured by a usual 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 each tire member at an unvulcanized stage, and attached by a normal method on a tire molding machine. The green tire is molded. The green tire is heated and pressed in a vulcanizer to obtain a tire. The pneumatic tire of the present invention obtained in this way has an improved workability in a factory without the rubber composition being used being adversely affected by its physical properties. Is also excellent. The tire may be filled not only with air but also with nitrogen or the like.

[0021]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, compounds represented by the following general formula (II) (provided that x,
The values of y and z and the types of M and R groups are shown in Table 1) were used as additives for the rubber composition.

[0022]

Embedded image [In the formula (II), when x is 0, it means that (CH ₂ CH ₂ O) does not exist, and when it is 1 or more, the average polymerization degree is shown. y and z are 0 or an integer of 1 or more, M is hydrogen or a metal atom, and R is alkyl or alkenyl. ]

[0023]

[Table 1]

Examples 1 to 13 and Comparative Examples 1 to 7 For 100 parts by weight of the rubber component shown in Table 2, the type and amount of the above additive for rubber composition, carbon black (ISAF) 50 shown in the table are used. Parts by weight, stearic acid 2 parts by weight, zinc white 3 parts by weight, antioxidant 6PPD [N-phenyl-
N '-(1,3-dimethylbutyl) -p-phenylenediamine] 1 part by weight, sulfur 1.5 parts by weight, vulcanization accelerator CB
One part by weight of S (N-cyclohexylbenzothiazylsulfenamide) was compounded and kneaded to prepare an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was further kneaded three times. In addition, only the comparative example 1 made the kneading frequency 4 times.

[0025]

[Table 2]

The obtained unvulcanized rubber composition was evaluated for processability (Mooney viscosity), process stability (Mooney scorch time), vulcanizability (T90) and odor by the following methods. The results are shown in Table 2. <Mooney viscosity (ML _{1 + 4} )> To evaluate the processability of the rubber composition, MOONYVISCO manufactured by Shimadzu was used.
Using METERSMV201, the unvulcanized rubber composition sample kneaded with the vulcanization-based compounding agent was heated at 130 ° C. for 1 minute, then the rotor was started to rotate, and the value after 4 minutes was defined as ML ₁₊ Measured as ₄ . At this time, the value of Comparative Example 1 was set to 100 and indexed. The larger the value of the Mooney viscosity, the better the workability.

<Mooney Scorch Time> JIS K6300-199 was used to evaluate the processing stability of the rubber composition.
In accordance with 4, using the same device as the Mooney viscosity test, for the unvulcanized rubber composition added to the vulcanized system and kneaded,
Measured at 130 ° C, the value from the beginning of residual heat is the lowest value V
The time required to rise 5 units above m was measured. On this occasion,
Indexing was performed with the value of Comparative Example 1 as 100. The smaller the Mooney scorch time, the better the processing stability. <Vulcanizability (T90)> As an evaluation of the appropriate vulcanizability of the rubber composition, a 90% vulcanization time (T90) when measured at 150 ° C. based on the vibration vulcanization test of JIS K6300-1994. Was measured. At this time, the value of Comparative Example 1 was set to 1
It was indexed as 00. The smaller the value is, the shorter the vulcanization time is and the better the vulcanization productivity is. <Odor> The odor felt during weighing and during kneading was evaluated by 10 persons from the viewpoint of an operator according to the following criteria. ：: All 10 persons do not feel odor. Δ: 1 to 9 people smell. ×: All 10 people smell.

The rubber composition of Comparative Example 2 is inferior in workability as compared with the rubber composition of Comparative Example 1 in which the number of kneadings is large. On the other hand, comparing Examples 1 to 13 with Comparative Example 2, it can be seen that the processability is improved even if the number of kneading is reduced, and that the physical properties of the vulcanized rubber composition are maintained. Further, as shown in Examples 11 and 12, the present invention is effective not only for natural rubber but also for rubber obtained by blending natural rubber and synthetic rubber. In Comparative Examples 4 to 6, since the type of the rubber composition additive was an alkyl ester and not a (poly) oxyalkylene ester in the present invention, there was no decrease in the physical properties of the unvulcanized rubber composition. For example, as shown in Comparative Examples 5 and 6, the working environment is deteriorated due to odor, and the vulcanized rubber composition has a large bloom as shown in Comparative Examples 10 and 11 described later. Further, in Comparative Examples 3 and 7 in which all carboxyl groups were converted into esters and / or metal salts, no effect was exerted on physical properties such as processability, indicating that a carboxyl group was essential. <Production of Additive Composition for Rubber Composition> Production Examples 1 to 11 According to the formulation in Table 3, silica, carbon black or clay as the component (a) was stirred with a Henschel mixer while the component (b) was used. A carboxylic acid derivative;
A (poly) oxyalkylene derivative or a polyhydric alcohol fatty acid ester having a melting point of 20 ° C. or less and a boiling point of 150 ° C. or more as a component (c) was added and mixed to obtain an additive composition for a rubber composition. Table 3 shows the properties of the obtained rubber composition additive composition.

[0029]

[Table 3]

The additive compositions of Production Examples 1 to 10 according to the present invention are easy to handle as solids. In addition, the additive compositions of Production Examples 3 to 8 and 10 are hardly dusted by the addition of the component (c), and are in the form of powder containing particles which is more advantageous in handling. In contrast, the additive composition of Production Example 11 became clay-like and was difficult to handle, so that a rubber composition could not be produced.

Examples 14 to 27 With respect to 100 parts by weight of the rubber component shown in Table 4, the type and amount of the additive composition for rubber composition obtained in Production Tables 1 to 10 above were used. The amount is shown as the amount of the component (b) in the composition], carbon black (IS
AF) 50 parts by weight, stearic acid 2 parts by weight, zinc white 3 parts by weight, antioxidant 6PPD [N-phenyl-N'-
(1,3-dimethylbutyl) -p-phenylenediamine] was added and kneaded, and then 1.5 parts by weight of sulfur as a vulcanizing compounding agent and a vulcanization accelerator CBS (N-
Cyclohexylbenzothiazylsulfenamide (1 part by weight) was added, and rubber kneading was performed the number of times shown in Table 4 to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was evaluated for physical properties such as Mooney viscosity (processability), Mooney scorch time, vulcanizability, and odor by the above methods. Table 4 shows the results. Example 28 Preparation of an unvulcanized rubber composition in the same manner as in Example 17, except that 25 parts by weight of carbon black and 25 parts by weight of silica were used instead of 50 parts by weight of carbon black. Was evaluated. The results are shown in Table 4.

[0032]

[Table 4]

(Note) * PHR: The number of parts by weight based on 100 parts by weight of the rubber component. As can be seen from the above results, the example in which the component (b) was blended as the rubber composition additive composition (B) prepared in advance. In 14 to 27, the same can be said for the first to thirteenth embodiments. Further, as shown in Example 28, it is understood that the present invention does not limit the filler to carbon black.

Examples 29 to 34 and Comparative Examples 8 to 11 From the rubber compositions shown in Tables 2 and 4, the uncured rubber compositions shown in Table 5 were used at 145 ° C. for 33 minutes. It was vulcanized to prepare a vulcanized rubber composition sample. The rupture strength, rupture elongation, rebound resilience, abrasion resistance and blooming property of the obtained vulcanized rubber composition sample were measured by the following methods. The results are shown in Table 5. <Breaking strength, breaking elongation> Dumbbell-shaped No. 3 was used for the test piece. The test method and the value of the result are based on JIS K6251-
According to 1993. The results were indexed with the value of Comparative Example 9 taken as 100. <Rebound resilience> Freely drop a predetermined weight on the rubber surface,
The value was the height at which the weight jumped up (% of the dropped height). The test method and the value of the result
According to ISK6301-1995. The results were indexed with the value of Comparative Example 9 taken as 100.

<Abrasion resistance> According to the Lambourn abrasion test,
The amount of abrasion was measured according to JIS K6264-1993. As a result, the reciprocal of the amount of wear in each example was indexed with the value of the reciprocal of the amount of wear obtained in Comparative Example 9 being 100. <Presence / absence of bloom> After vulcanization, the vulcanized rubber composition sample was allowed to stand in a 5 ° C. atmosphere for 12 weeks, and the toluene soluble matter on the rubber composition sample surface was analyzed by a gas chromatograph and a mass spectrometer. The presence / absence of precipitation of a substance derived from the additive composition for product and the additive composition for rubber composition was examined. The measurement conditions at this time were as follows: the gas chromatography was performed at an injection temperature of 280 ° C.
The column is kept at 70 ° C for 1 minute and then at 300C at 25 ° C / min.
Then, when the temperature reached 300 ° C., it was kept for 10 minutes. Helium was used as the carrier gas, and the flow rate of the carrier gas was 1 ml / min. For the mass spectrometer, the scan range was M / Z: 25-500. As a result, the presence or absence of bloom was evaluated as follows. ：: No precipitation of the above substances was confirmed. ×: Precipitation of the above substance was confirmed.

[0036]

[Table 5]

In Examples 29 to 34, even if the number of times of rubber kneading was reduced, the physical properties of the vulcanized rubber composition were not adversely affected, and there was no problem with blooming. However, Comparative Example 10 in which the ester (b) was not used in the present invention was used. , 11 have blooms on the rubber surface. As described above, when the specific ester in the present invention is compounded in the rubber composition, even if the number of times of rubber kneading is reduced, the rubber physical properties are not substantially reduced from the entire rubber kneading process to the rubber product. I understand.

[0038]

According to the rubber composition additive and the rubber composition additive composition of the present invention, the processability is improved without impairing the physical properties of the rubber, and the surface state of the unvulcanized and vulcanized rubber is improved. Thus, a rubber composition having no problem can be obtained stably, and therefore, the productivity can be improved and the rubber composition can be suitably used particularly for a pneumatic tire.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/12 C08K 5/12 C08L 71/02 C08L 71/02 (72) Inventor Daisuke Nohara Kodaira, Tokyo 3-1-1 Ogawa Higashicho Inside Bridgestone Technology Center Co., Ltd. (72) Inventor Isao Nishi 1334 Minato, Wakayama-shi, Wakayama Pref. Inside the laboratory (72) Inventor Tetsuo Takano 1334 Minato, Wakayama, Wakayama Pref.

Claims (9)

[Claims] An additive for a rubber composition, which is an ester of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule. . 2. A reinforcing filler (a) and an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule. And (b) of the component (a)
The weight ratio (a) / (b) to the components is 70 / 30-
An additive composition for a rubber composition, which is 30/70. 3. The composition further comprises at least one component (c) selected from (poly) oxyalkylene derivatives, alcohols and fatty acid esters thereof, and the amount of the component (a) and component (b) The additive composition for a rubber composition according to claim 2, wherein the amount is 10 parts by weight or less based on 100 parts by weight in total. 4. The additive composition for a rubber composition according to claim 3, wherein the component (c) has a melting point of 20 ° C. or lower and a boiling point of 150 ° C. or higher. 5. The rubber component (A) is compounded with an ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule. A rubber composition comprising: 6. The rubber composition according to claim 5, further comprising a reinforcing filler (a). 7. An ester (b) of an aromatic polycarboxylic acid and a (poly) oxyalkylene derivative having at least one carboxyl group bonded to an aromatic ring in the molecule in the rubber component (A), and reinforcement. A rubber composition characterized by being compounded with an additive composition (B) for a rubber composition comprising a conductive filler (a). 8. The rubber composition additive composition (B) blended with the rubber component (A) further comprises at least one kind selected from (poly) oxyalkylene derivatives, alcohols and fatty acid esters thereof. 8. The rubber composition according to claim 7, wherein c) is contained. 9. A pneumatic tire using the rubber composition according to any one of claims 5 to 8.