JP5459047B2 - Adhesive rubber composition and pneumatic tire using the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an adhesive rubber composition and a pneumatic tire using the same, and more specifically, has high initial adhesion and water-resistant adhesion to steel cords, and has physical properties even when vulcanized at high temperatures. The present invention relates to an adhesive rubber composition in which the decrease in the resistance is small and a pneumatic tire using the same.

In order to improve the durability of the tire, it is important to improve the adhesion between the steel cord and the rubber. In general, steel cords are brass-plated, and rubber is mixed with organic acid cobalt salt to enhance adhesion. However, when the tire is exposed to wet heat for a long time, there is a problem that the adhesive strength is reduced.
In order to solve this problem, Patent Documents 1 and 2 listed below include cobalt-boron metal soaps of organic carboxylic acids for improving the adhesion between a steel cord for rubber reinforcement and rubber, particularly for improving adhesion after wet heat aging. It has been proposed to be used as an adhesion promoter. However, the organic carboxylic acid cobalt / boron metal soap has a remarkable improvement effect on the wet heat degradation of the adhesive, but has a problem that the physical properties are liable to deteriorate during high temperature vulcanization.
Patent Document 3 discloses a technique using a specific cobalt-boron metal soap, but has not yet been improved sufficiently.

JP-A-55-17371 JP-A-60-158230 Japanese Patent No. 2823857

  An object of the present invention is to provide an adhesive rubber composition having high initial adhesion and water-resistant adhesion to a steel cord, and having little deterioration in physical properties even when vulcanized at a high temperature, and a pneumatic tire using the same There is to do.

As a result of intensive research, the present inventors have found that the above problem can be solved by blending a specific amount of organic acid cobalt salt containing boron and a specific amount of polyethylene glycol having a specific molecular weight range into diene rubber. The headline and the present invention could be completed.
That is, the present invention is as follows.
1. 0.1 to 0.4 parts by mass of polyethylene glycol having an organic acid cobalt salt containing boron as a cobalt amount and 0.1 to 3.0 parts by mass of the number average molecular weight is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the diene rubber. An adhesive rubber composition characterized by being partly blended.
2. For 100 parts by mass of diene rubber, 0.5 to 5 parts by mass of at least one selected from resorcin resin and cresol resin, and a partial condensate of hexamethylol melamine pentamethyl ether and hexamethoxymethylol melamine 2. The adhesive rubber composition as described in 1 above, wherein 0.5 to 5 parts by mass of at least one selected from partial condensates is blended.
3. A pneumatic tire using the adhesive rubber composition according to 1 or 2 above.

  According to the present invention, high initial adhesiveness and water-resistant adhesion to a steel cord can be obtained by blending a specific amount of organic acid cobalt salt containing boron and a specific amount of polyethylene glycol having a specific molecular weight range into diene rubber. It is possible to provide an adhesive rubber composition and a pneumatic tire using the same, which have properties and have little deterioration in physical properties even when vulcanized at high temperatures.

Hereinafter, the present invention will be described in more detail.
(Diene rubber)
As the diene rubber component used in the present invention, any diene rubber that can be blended in a normal rubber composition can be used. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), and the like. These may be used alone or in combination of two or more. The molecular weight and microstructure are not particularly limited, and may be terminally modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group or the like, or may be epoxidized.
Among these diene rubbers, the diene rubber is preferably NR from the viewpoint of the effect of the present invention.

(Organic acid cobalt salt containing boron)
Examples of the organic acid cobalt salt containing boron used in the present invention include Rhono Manobond C22.5 and Manobond 680C, Jhepherd CoMend A and CoMend B, and Dainippon Ink & Chemicals NBC-2. can do.

(Polyethylene glycol)
The polyethylene glycol used in the present invention needs to have a number average molecular weight of 200 to 600. When the number average molecular weight is less than 200, it sublimates during mixing at high temperature or during vulcanization, and the effects of the present invention are not sufficiently exhibited. When the number average molecular weight exceeds 600, initial adhesiveness and water-resistant adhesiveness deteriorate. The number average molecular weight referred to in the present invention is a value measured by gel permeation chromatography (GPC) and converted to polystyrene.

(Blend ratio of adhesive rubber composition)
The adhesive rubber composition of the present invention is a polyethylene having 0.1 to 0.4 parts by mass and a number average molecular weight of 200 to 600, based on 100 parts by mass of diene rubber, based on cobalt as an organic acid cobalt salt containing boron. It is characterized by blending 0.1 to 3.0 parts by mass of glycol.
When the compounding amount of the organic acid cobalt salt containing boron is less than 0.1 parts by mass as the cobalt amount, the compounding amount is too small to achieve the effects of the present invention. On the other hand, when it exceeds 0.4 parts by mass, the water-resistant adhesiveness is deteriorated, and the physical properties are significantly lowered when vulcanized at a high temperature. Moreover, it is also possible to use together with organic acid cobalt, such as cobalt naphthenate conventionally used, and the total compounding quantity in that case is the same as the above.
When the blending amount of the polyethylene glycol is less than 0.1 parts by mass, the blending amount is too small to achieve the effects of the present invention. On the other hand, when it exceeds 3.0 parts by mass, the physical properties are significantly lowered when vulcanized at a high temperature.

Furthermore, the compounding quantity of the organic acid cobalt salt containing a preferable boron is 0.12-0.30 mass part with respect to 100 mass parts of diene rubbers.
A more preferable blending amount of the polyethylene glycol is 0.5 to 2.5 parts by mass with respect to 100 parts by mass of the diene rubber.

In this invention, it is preferable to mix | blend at least 1 sort (s) chosen from the resorcinol resin and the cresol resin from a viewpoint of the effect improvement.
The resorcin resin used in the present invention is a compound obtained by reacting resorcin and formaldehyde. For example, Penacolite B-18-S, B-19-S, B-20-S, B-20 manufactured by INDSPEC Chemical Corporation. -21-S, Sumikanol 620 manufactured by Taoka Chemical Industry Co., Ltd. can be exemplified. The cresol resin is a compound obtained by reacting cresol and formaldehyde, and a compound using m-cresol is particularly preferable. Examples of the cresol resin include Sumikanol 610 manufactured by Taoka Chemical Co., Ltd. and SP7000 manufactured by Nippon Shokubai Co., Ltd.
The blending amount of at least one selected from resorcin resin and cresol resin is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

Moreover, in this invention, it is preferable to mix | blend at least 1 sort (s) chosen from the partial condensate of hexamethylol melamine pentamethyl ether and the partial condensate of hexamethoxymethylol melamine from the viewpoint of the effect improvement.
As a partial condensate of hexamethylol melamine pentamethyl ether used in the present invention, for example, Sumikanol 507A manufactured by Taoka Chemical Industry Co., Ltd. can be exemplified. Examples of the partial condensate of hexamethoxymethylolmelamine include CYREZ 964RPC manufactured by CYTEC INDUSTRIES.
The blending amount of at least one selected from a partial condensate of hexamethylol melamine pentamethyl ether and a partial condensate of hexamethoxymethylol melamine is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

  The adhesive rubber composition of the present invention includes an adhesive rubber composition such as a vulcanization or cross-linking agent, a vulcanization or cross-linking accelerator, various fillers, various oils, an anti-aging agent, and a plasticizer in addition to the components described above. Various additives generally blended into products can be blended, and such additives can be kneaded by a general method to form a composition, which can be used for vulcanization or crosslinking. The blending amounts of these additives can be set to conventional general blending amounts as long as the object of the present invention is not violated.

  The adhesive rubber composition of the present invention has excellent adhesion to steel cords generally used for, for example, belt conveyors, hoses, tires and the like. For example, in the case of tire applications, examples of the steel cord include a belt, a carcass, and a bead (including a bead core and a steel cord housed therein) embedded in an undertread. The steel cord is preferably brass-plated.

  Applications of the adhesive rubber composition of the present invention include belt conveyors, hoses, tires and the like, and tire applications are particularly preferable.

  The adhesive rubber composition of the present invention can be used for producing a pneumatic tire according to a conventional method for producing a pneumatic tire.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Examples 1-8 and Comparative Examples 1-9
Sample preparation In the formulation (parts by mass) shown in Tables 1 and 2, the components excluding the vulcanization system (vulcanization accelerator, sulfur) were kneaded with a 1.7 liter closed Banbury mixer for 5 minutes, and then outside the mixer. Release and cool to room temperature. Subsequently, the composition was put into the Banbury mixer again, and a vulcanization system was added and kneaded to obtain an adhesive rubber composition. Using the obtained adhesive rubber composition, physical properties were measured by the following test methods.

M50: In accordance with JIS K6251, using the above adhesive rubber composition, a sheet vulcanized at 160 ° C. for 30 minutes and a sheet vulcanized at 180 ° C. for 5 minutes are molded into a No. 3 type dumbbell test piece and pulled. 50% modulus (M50) was measured under conditions of a speed of 500 mm / min, a temperature of 23 ° C., and a temperature of 100 ° C. The result of using the sheet of Comparative Example 1 or 7 vulcanized at 160 ° C. for 30 minutes was expressed as 100 as an index. The larger the index, the higher the elastic modulus, which means that the decrease in physical properties during vulcanization at high temperatures is suppressed.
Initial adhesion: The rubber composition was coated and embedded from both sides of brass plated steel cords (1 × 5 structure) arranged in parallel with each other at an interval of 12.5 mm to obtain a 25 mm wide sheet as a test sample. This test sample was vulcanized at 180 ° C. for 12 minutes, and then the cord was drawn from the sample in accordance with ASTM D 2229 and evaluated by the pulling force (index) at that time. The result of Comparative Example 1 or 7 was taken as 100 and indicated as an index. A larger index means better initial adhesion.
Water-resistant adhesion: The test sample after vulcanization was cut and immersed in warm water at 70 ° C. for 4 weeks, and then evaluated according to ASTM D 2229 in the same manner as described above.
The results are shown in Tables 1 and 2 together.

* 1: NR (RSS # 3)
* 2: Carbon black (trade name Seast N, HAF grade carbon black manufactured by Tokai Carbon Co., Ltd.)
* 3: Zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd., three types of zinc oxide)
* 4: Anti-aging agent (Seiko Chemical Co., Ltd. Ozonon 6C)
* 5: Organic acid cobalt salt-1 (manufactured by DIC Corporation, cobalt naphthenate, cobalt content = 10 mass%)
* 6: Organic acid cobalt salt-2 (manufactured by Rhodia Manobond C22.5, organic acid cobalt salt containing boron, cobalt content = 22% by mass)
* 7: Propylene glycol (Propylene glycol for industrial use manufactured by ADEKA Corporation)
* 8: Polyethylene glycol-1 (PEG # 200 manufactured by NOF Corporation, number average molecular weight = 200)
* 9: Polyethylene glycol-2 (PEG # 600, NOF Corporation, number average molecular weight = 600)
* 10: Polyethylene glycol-3 (PEG # 1000 manufactured by NOF Corporation, number average molecular weight = 1000)
* 11: Insoluble sulfur (Mucron OT-20 manufactured by Shikoku Chemicals Co., Ltd.)
* 12: Vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd. Noxeller DZ-G)
* 13: PMMM (Sumikanol 507A manufactured by Taoka Chemical Co., Ltd., partial condensate of hexamethylol melamine pentamethyl ether)
* 14: HMMM (CYREZ 964RPC manufactured by CYTEC INDUSTRIES, partial condensate of hexamethoxymethylol melamine)
* 15: Cresol resin (Sumikanol 610 manufactured by Taoka Chemical Co., Ltd.)
* 16: Resorcin resin (Penacolite B-21-S manufactured by INDSPEC Chemical Corporation)

As apparent from Table 1 above, the adhesive rubber compositions prepared in Examples 1 to 4 are polyethylene glycol having specific amounts and specific molecular weight ranges of organic acid cobalt salts containing boron in a diene rubber. Since a specific amount is blended, the steel cord has high initial adhesiveness and water-resistant adhesiveness as compared to the conventional representative Comparative Example 1, and there is little decrease in physical properties even when vulcanized at high temperatures.
Since the comparative example 2 does not mix | blend polyethyleneglycol, the fall of the physical property at the time of vulcanizing at high temperature is remarkable.
Comparative Example 3 was an example in which propylene glycol was blended instead of polyethylene glycol, and a decrease in physical properties was observed when vulcanized at a high temperature. Moreover, water-resistant adhesiveness was not improved.
In Comparative Example 4, since the blending amount of polyethylene glycol exceeded the upper limit specified in the present invention, the physical properties were significantly lowered when vulcanized at high temperature, and the water-resistant adhesion was also deteriorated.
Since the number average molecular weight of polyethylene glycol exceeds the upper limit prescribed | regulated by this invention, the fall of the physical property at the time of vulcanizing at high temperature is remarkable in the comparative example 5.
Since the compounding quantity of the organic acid cobalt salt containing a boron exceeds the upper limit prescribed | regulated by this invention in the comparative example 6, the fall of the physical property at the time of vulcanizing at high temperature was remarkable, and the water-resistant adhesiveness also deteriorated. .

Further, as is apparent from Table 2 above, the adhesive rubber compositions prepared in Examples 5 to 8 are polyethylene having a specific amount and a specific molecular weight range of the organic acid cobalt salt containing boron in the diene rubber. A specific amount of glycol is blended, and a specific amount of resorcin resin or cresol resin is blended, and a specific amount of PMMM or HMMM is blended. In addition, deterioration of physical properties when vulcanized at high temperatures is also suppressed.
Comparative Example 8 is an example in which propylene glycol was blended instead of polyethylene glycol, and a decrease in physical properties was observed when vulcanized at a high temperature. Moreover, water-resistant adhesiveness was not improved.
In Comparative Example 9, since the blending amount of polyethylene glycol exceeded the upper limit specified in the present invention, the physical properties were significantly deteriorated when vulcanized at a high temperature, and the water-resistant adhesion was not improved.

Claims (3)

  0.1 to 0.4 parts by mass of polyethylene glycol having an organic acid cobalt salt containing boron as a cobalt amount and 0.1 to 3.0 parts by mass of the number average molecular weight is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the diene rubber. An adhesive rubber composition characterized by being partly blended.   For 100 parts by mass of diene rubber, 0.5 to 5 parts by mass of at least one selected from resorcin resin and cresol resin, and a partial condensate of hexamethylol melamine pentamethyl ether and hexamethoxymethylol melamine The adhesive rubber composition according to claim 1, wherein 0.5 to 5 parts by mass of at least one selected from partial condensates is blended.   A pneumatic tire using the adhesive rubber composition according to claim 1.