JP2005343995A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition while achieving a good bonding property with a metal, and equipped with a good processability, heat-generating property, tensile physical properties and high temperature physical properties (high temperature tensile characteristics) jointly after its vulcanization as compared with those of conventional technologies. <P>SOLUTION: This rubber composition obtained by blending a tris(acetylacetonate)cobalt (III) complex and a bis(acetylacetonate)copper (II) complex to a rubber component consisting of at least 1 kind of a diene-based rubber is characterized by having (60/40)-(40/60) molar ratio of the blending amount of the tris(acetylacetonate)cobalt (III) complex based on the metal element to the blending amount of the bis(acetylacetonate)copper (II) complex based on the metal element, and 0.15-0.40 pt. wt. total blending amount of the tris(acetylacetonate)cobalt (III) complex and bis(acetylacetonate)copper (II) complex as the metal elements, based on 100 pts. wt. rubber component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition. More particularly, the present invention relates to rubber products (eg, belts, edge tapes, carcass, bead insulation, and rim cushions in tires, and seismic isolation rubber) that require good adhesion to metal (eg, steel). , Rubber crawlers, belt conveyors, etc.).

  When good adhesion to metal is required in rubber products, it is common to improve the adhesion of rubber products after vulcanization to metal (for example, steel) by adding a large amount of sulfur to the rubber composition. Is.

  However, when a large amount of sulfur is blended as described above, the heat aging resistance of the rubber composition after vulcanization is lowered, and depending on the use conditions, the rubber composition after the vulcanization is cured and the life as a rubber product is increased. Inconvenience occurs.

  Therefore, as an attempt to improve the adhesion to metal, as an adhesion promoter compounded in the rubber composition, one or more metal fatty acid salts selected from nickel, zinc, and zirconium (for example, neodecanoate) ) And an organic cobalt compound (for example, cobalt neodecanoate) has been proposed (Patent Document 1).

  On the other hand, for example, in the case of a vehicle tire, the tire generates heat due to friction with the road surface and internal distortion (deformation). Adhesiveness decreases. In addition, when moisture is present due to rain, snow, etc., it becomes a high temperature and humidity condition combined with the above heat generation, so that the adhesion between the rubber and the steel cord is further lowered, and the tires such as separation of the belt part are serious. It is known that it is easy to cause a failure.

  Furthermore, the fact that the physical properties of rubber at high temperatures are generally lower than the physical properties of rubber at room temperature is also considered to be a cause of the decrease in durability of rubber products.

  Therefore, as a countermeasure against the above problem, a resin is blended in the rubber composition to reduce deformation of the rubber composition (for example, Patent Document 2 and Patent Document 3), or silica is blended in the rubber composition (for example, Patent Document 4) and proposals have been made to suppress the heat generation of rubber products by blending a low heat generation carbon black with the rubber composition (for example, Patent Document 5 and Patent Document 6).

  However, in the above method, problems of workability such as sticking to a rubber composition mixer and poor kneading uniformity of the rubber composition often occur when the rubber composition is kneaded.

  As described above, in this technical field, there is still a demand for rubber products that have higher levels of workability, heat generation, tensile properties, and high temperature properties (high temperature tensile properties). Suitable rubber compositions are being sought.

Prior art document information related to the invention of this application includes the following.
Japanese Patent Laid-Open No. 11-60820 JP 2001-226528 A Japanese Examined Patent Publication No. 63-4582 JP-A-7-102115 Japanese Patent Laid-Open No. 7-149957 JP-A-6-25473

  The present invention provides a rubber composition that achieves good workability, heat generation, tensile properties, and high temperature properties (high temperature tensile properties) after vulcanization while achieving good adhesion to metals. The purpose is to provide.

An object of the present invention is to provide a rubber composition comprising a rubber component comprising at least one diene rubber and a tris (acetylacetonato) cobalt (III) complex and a bis (acetylacetonato) copper (II) complex. Because
The molar ratio of the amount of the tris (acetylacetonato) cobalt (III) complex as the metal element to the amount of the bis (acetylacetonato) copper (II) complex as the metal element is 60/40 to 40 / 60, and the total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is 100 parts by weight of the rubber component, 0.15 to 0.40 parts by weight,
This is achieved by a rubber composition characterized in that.

  According to the present invention, there is provided a rubber composition having good workability, exothermic property, tensile physical property, and high temperature physical property (high temperature tensile property) after vulcanization while achieving good adhesion to metal. Provided. As described above, the rubber composition according to the present invention achieves good workability, exothermic property, tensile physical property, and high temperature physical property (high temperature tensile property) as compared with the prior art while achieving good adhesion to metal. For example, it is suitable for use in the manufacture of belts, edge tapes, carcass, bead insulation, rim cushions, seismic isolation rubbers, rubber crawlers, belt conveyors and the like in tires.

  The present invention specifies tris (acetylacetonato) cobalt (III) complex and bis (acetylacetonato) copper (II) complex as an adhesion promoter for rubber components composed of at least one diene rubber. By blending at a ratio of 1, a rubber composition that has good workability, exothermic properties, tensile properties, and high-temperature properties (high-temperature tensile properties) compared to the prior art while achieving good adhesion to metals Is based on the finding that can be provided.

That is, the rubber composition according to the present invention comprises a tris (acetylacetonato) cobalt (III) complex and a bis (acetylacetonato) copper (II) complex for a rubber component composed of at least one diene rubber. A rubber composition comprising:
The molar ratio of the amount of the tris (acetylacetonato) cobalt (III) complex as the metal element to the amount of the bis (acetylacetonato) copper (II) complex as the metal element is 60/40 to 40 / 60, and the total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is 100 parts by weight of the rubber component, 0.15 to 0.40 parts by weight,
It is a rubber composition characterized by this.

  The rubber component used in the rubber composition according to the present invention is not particularly limited, and any of natural rubber (NR) and diene synthetic rubber, or a mixed system thereof can be used. Examples of the diene-based synthetic rubber include various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene rubber (IR), butyl rubber (IIR), acrylonitrile-butadiene rubber, chloroprene rubber, ethylene- Examples include propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, and isoprene-butadiene copolymer rubber.

  In the rubber composition according to the present invention, a molar amount of the tris (acetylacetonato) cobalt (III) complex as a metal element with respect to a blending amount of the bis (acetylacetonato) copper (II) complex as a metal element. The ratio is desirably 60/40 to 40/60, preferably 55/45 to 45/55. When the ratio exceeds 60/40, the heat build-up of the rubber composition after vulcanization increases, and the tensile properties (specifically, elongation at break) decrease, which is not preferable. Conversely, when the ratio is less than 40/60, the high temperature physical properties (high temperature tensile properties) (specifically, elongation at break) of the rubber composition after vulcanization are not preferable.

  In the rubber composition according to the present invention, the total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is 100% of the rubber component 100. It is desirable that the amount be 0.15 to 0.40 parts by weight, preferably 0.18 to 0.30 parts by weight with respect to parts by weight. The total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is less than 0.15 parts by weight with respect to 100 parts by weight of the rubber component. In some cases, the high temperature physical properties (high temperature tensile properties) (specifically, elongation at break) of the rubber composition after vulcanization are not preferable. Conversely, the total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is 0.40 weight with respect to 100 parts by weight of the rubber component. Exceeding a part is not preferable because the exothermic property of the rubber composition after vulcanization is increased and the high-temperature properties (high-temperature tensile properties) (specifically, the breaking strength) is lowered. In the present specification, the term “organometallic compound” is used as a general term for organometallic complexes and organometallic salts.

  As described above, the present invention achieves good workability, exothermic property, tensile physical property, and high temperature physical property (high temperature tensile property) after vulcanization as compared with the prior art while achieving good adhesion to metal. An object is to provide a rubber composition. Therefore, a vulcanizing agent such as sulfur is also added to the rubber composition according to the present invention. When sulfur is used as the vulcanizing agent, for example, those known in the rubber compounding technical field such as powdered sulfur can be used.

  In this case, the compounding amount of the vulcanizing agent in the rubber composition according to the present invention can be a compounding amount known in the technical field. Specifically, it is preferable to blend 3.5 to 13 parts by weight, preferably 5 to 10 parts by weight, of the vulcanizing agent with respect to 100 parts by weight of the rubber component.

  Further, as widely practiced in the technical field, an anti-aging agent such as an amine anti-aging agent is further added to the rubber composition according to the present invention to improve the anti-aging property of the rubber composition. May be.

  In this case, the blending amount of the anti-aging agent in the rubber composition according to the present invention can be a blending amount known in the technical field. Specifically, it is desirable to mix 0.5 to 8.0 parts by weight, preferably 1.0 to 7.0 parts by weight of an anti-aging agent with respect to 100 parts by weight of the rubber component.

  The rubber composition according to the present invention further includes a filler (for example, carbon black, silica), process oil, plasticizer, softener, vulcanization aid, vulcanization accelerator, vulcanization activator, and the like. Various other additives generally used in the rubber compounding technical field can be compounded. 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 rubber composition according to the present invention can be produced by mixing the above components using a known rubber kneading machine (for example, a roll, a Banbury mixer, a kneader, etc.).

  The rubber composition according to the present invention can be used in various rubber products such as tires and belts. In particular, the rubber composition according to the present invention exhibits good processability, heat generation, tensile properties, and high-temperature properties (high-temperature tensile properties) in rubber products that require high adhesion to metals after vulcanization. This is extremely useful when trying to make it happen. In particular, the rubber composition according to the present invention is preferably used as a rubber composition for coating steel cords for tires.

  The present invention will be described in more detail with reference to the following standard examples, comparative examples, and examples. However, the technical scope of the present invention is not limited to these examples.

Standard Examples, Comparative Examples 1-6, and Examples 1 and 2
Compounding Components Various compounding components used in the preparation of various test samples described below are listed below.

Natural rubber (NR): RSS No. 3 Carbon black (CB): “Carbon black N326” manufactured by Tokai Carbon Corporation
Zinc Hana: “Zinc Oxide”
Anti-aging agent (6C): “Antigen 6C” (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Vulcanization accelerator (DZ): “Noxeller DZ” (N, N-dicyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization retarder (PVI): "SANTOGARD PVI" (N-cyclohexylthiphthalimide) manufactured by FLEXSYS
Sulfur: Tsurumi Chemical Co., Ltd. “Jinhua seal 5% oil-filled fine sulfur”

Organometallic compound 1 (BCo): “Manobond” (Cobalt (III) neoborate orthoborate) manufactured by Rhodia (metal element content = about 22.0% by weight)
Organometallic compound 2 (Co (acac) ₃ ): “Narsem second cobalt” (tris (acetylacetonato) cobalt (III) complex) manufactured by Nippon Kagaku Sangyo Co., Ltd. (metal element content = about 16.5% by weight)
Organometallic compound 3 (Cu (acac) ₂ ): “Narsem copper” (bis (acetylacetonato) copper (II) complex) manufactured by Nippon Kagaku Sangyo Co., Ltd. (metal element content = about 24.3 wt%)

Preparation of samples (1) Preparation of various rubber compositions Ingredients other than sulfur and vulcanization accelerator shown in Table I below are mixed and kneaded with a Banbury mixer and a kneading roll machine in the compounding amounts shown in Table I below. The masterbatch was released when 165 ± 5 ° C was reached. To this master batch, sulfur and a vulcanization accelerator having the blending amounts shown in Table I below were added, and kneaded with an 8-inch open roll, and the standard examples, Comparative Examples 1 to 6, and Examples 1 and 2 were used. A rubber composition was obtained.

(2) Preparation of various test pieces Various rubber compositions obtained as described above were press vulcanized at 160 ° C. for 15 minutes in a 15 × 15 × 0.2 cm mold to obtain various target test pieces. Prepared.

Measurement of physical properties of samples (1) Measurement of unvulcanized physical properties of various rubber compositions The unvulcanized physical properties of various rubber compositions obtained in the standard examples, comparative examples 1 to 6, and examples 1 and 2 are as follows. It was measured according to the test method.

1) Mooney viscosity (MV):
The Mooney viscosities (ML1 + 4, 100 ° C.) of the various unvulcanized rubber compositions were measured according to JIS K6300, and displayed as an index with the measured value of the standard example as 100. The larger this index, the higher the viscosity of the unvulcanized rubber composition and the lower the processability.

(2) Measurement of vulcanized physical properties of various test pieces Various vulcanized physical properties of the above test pieces made of various rubber compositions obtained in standard examples, comparative examples 1 to 6 and examples 1 and 2 were tested as follows. Measured according to the method.

2) Loss tangent (tan δ):
Using the viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for the above various test pieces, the ambient temperature was 20 ° C., 60 ° C., and 100 under conditions of initial strain 10%, amplitude ± 2%, frequency 20 Hz. The loss tangent tan δ was measured at 0 ° C. and expressed as an index with the loss tangent tan δ of the standard example as 100. The higher the index, the higher the heat generation. For example, when used in a vehicle tire, there is a concern about tire failure due to heat generated by friction with the road surface or internal distortion (deformation).

3) Tensile properties after aging:
The rupture strength (TB) and rupture elongation (EB) at various ambient temperatures of the above-mentioned various test pieces after being aged by holding at 80 ° C. for 96 hours (dumbbell-shaped type 3) were measured according to JIS K6251 (former JIS). K6301) and measured with an index with the measured value of the standard example as 100. The larger this index, the higher the heat aging resistance of the rubber composition after vulcanization.

4) High temperature tensile properties after aging:
The rupture strength (TB) and elongation at break (EB) at 100 ° C. of the above-mentioned various test pieces (dumbbell-shaped No. 3 type) after aging by holding at 80 ° C. for 96 hours are JIS K6251 (former JIS K6301) and measured with an index with the measured value of the standard example as 100. It means that the higher the index, the higher the high temperature physical properties of the rubber composition after vulcanization.

Evaluation of Samples The results of various physical properties measured in the above 1) to 4) for the various rubber compositions and various test pieces are also shown in Table I above. As shown in Table I above, in all examples, the compounding amounts of components other than the organometallic compound are the same.

  The rubber composition of the standard example has a composition of a standard belt rubber formed by blending 1.00 part by weight of an organometallic compound 1 (BCo) with respect to 100 parts by weight of a rubber component made of natural rubber (NR). It is a rubber composition used as a reference standard. As described above, in the measurement of various physical properties, the physical properties of various samples were compared and evaluated based on the measurement results of the rubber composition of the standard example.

In the rubber composition of Comparative Example 1, the amount of the organometallic compound as a metal element was maintained at 0.22 parts by weight with respect to 100 parts by weight of the rubber component, while the organometallic compound 1 (BCo) was replaced by an organometallic compound. A comparative rubber composition having the same composition as the rubber composition of the standard example except that compound 2 (Co (acac) ₃ ) was blended. As a result of blending the organometallic compound 2 (Co (acac) ₃ ) alone as the organometallic compound, the exothermic property of the test piece after vulcanization increased, and the tensile properties (specifically, elongation at break) also decreased.

In the rubber composition of Comparative Example 2, instead of compounding the organometallic compound 2 (Co (acac) ₃ ) alone as the organometallic compound, the total blending amount of the organometallic compound as the metal element is 100 parts by weight of the rubber component. On the other hand, the molar ratio of the compounding amount as a metal element is 80/20 while maintaining the content at 0.22 parts by weight, and the organometallic compound 2 (Co (acac) ₃ ) and the organometallic compound 3 (Cu (acac) ₂ ) A rubber composition for comparison having the same composition as the rubber composition of Comparative Example 1 except that the combination of Although a combination of organometallic compound 2 (Co (acac) ₃ ) and organometallic compound 3 (Cu (acac) ₂ ) is blended as the organometallic compound, the molar ratio (80/20) of the blending amount as the metal element is Since it deviates from the specified range (60/40 to 40/60) of the present invention, the exothermic property in the test piece after vulcanization increases as in Comparative Example 2 above, and tensile properties (specifically, The elongation at break was also reduced.

In the rubber compositions of Examples 1 and 2, the amount of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) as the metal element is the mole of the compounding amount of the organometallic compound 3 (Cu (acac) ₂ ) as the metal element. The rubber composition according to the present invention has the same composition as the rubber composition of Comparative Example 2 except that the ratio is 60/40 and 40/60, respectively. In these rubber compositions, the molar ratio of the organometallic compound 2 (Co (acac) ₃ ) to the organometallic compound 3 (Cu (acac) ₂ ) as the metal element is within the specified range (60/40 to As a result, compared with the standard example, it succeeded in achieving good exothermic properties, tensile physical properties, and high-temperature physical properties (high-temperature tensile physical properties).

In the rubber compositions of Comparative Examples 3 and 4, the molar amount of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) as the metal element with respect to the compounding amount of the organometallic compound 3 (Cu (acac) ₂ ) as the metal element It is a comparative rubber composition having the same composition as the rubber composition of Comparative Example 2 except that the ratio was 20/80 and 0/100, respectively. In these rubber compositions, the molar ratio of the organometallic compound 2 (Co (acac) ₃ ) to the organometallic compound 3 (Cu (acac) ₂ ) as the metal element is within the specified range (60/40 to 40/60). As a result, although the exothermic property and the tensile property at ambient temperature in the test piece after vulcanization were both good, the high-temperature property (high-temperature tensile property) (specifically, (Elongation at break) all decreased.

The rubber composition of Comparative Example 5 has a molar ratio of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) as the metal element to the compounding amount of the organometallic compound 3 (Cu (acac) ₂ ) as the metal element. While maintaining 40/60, the same composition as the rubber composition of Example 2 except that the total amount of the organometallic compound as a metal element was reduced to 0.10 parts by weight with respect to 100 parts by weight of the rubber component A comparative rubber composition having The molar ratio (40/60) of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) and the organometallic compound 3 (Cu (acac) ₂ ) as the metal element is within the specified range (60/40 to 40-40). / 60), but the total compounding amount (0.10 parts by weight) of these organometallic compounds as metal elements is below the specified range (0.15 to 0.40 parts by weight) of the present invention. As a result, although the exothermic property and the tensile physical property at ambient temperature in the test piece after vulcanization were good, the high temperature physical property (high temperature tensile physical property) (specifically, elongation at break) was lowered.

The rubber composition of Comparative Example 6 has a molar ratio of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) as the metal element to the compounding amount of the organometallic compound 3 (Cu (acac) ₂ ) as the metal element. While maintaining 40/60, the same composition as the rubber composition of Example 2 except that the total compounding amount of the organometallic compound as a metal element was increased to 0.50 parts by weight with respect to 100 parts by weight of the rubber component. A comparative rubber composition having The molar ratio (40/60) of the compounding amount of the organometallic compound 2 (Co (acac) ₃ ) and the organometallic compound 3 (Cu (acac) ₂ ) as the metal element is within the specified range (60/40 to 40-40). / 60), however, the total amount (0.50 parts by weight) of these organometallic compounds as metal elements exceeds the specified range (0.15 to 0.40 parts by weight) of the present invention. As a result, the exothermic property of the test piece after vulcanization increased, and the high temperature physical properties (high temperature tensile physical properties) (specifically, tensile strength) also decreased.

  The rubber compositions of Comparative Examples 1 to 6 and Examples 1 and 2 all have a low Mooney viscosity equal to or lower than that of the rubber composition of the standard example, and have good processability. Be expected.

From the above evaluation results, by using together the organometallic compound 2 (Co (acac) ₃ ) and the organometallic compound 3 (Cu (acac) ₂ ) in the blending amount and blending ratio defined in the present invention, the metal It is possible to provide a rubber composition having good processability, exothermic property, tensile physical property, and high temperature physical property (high temperature tensile property) after vulcanization, while achieving good adhesion to Became clear.

Claims (1)

A rubber composition comprising a rubber component comprising at least one diene rubber and a tris (acetylacetonato) cobalt (III) complex and a bis (acetylacetonato) copper (II) complex,
The molar ratio of the amount of the tris (acetylacetonato) cobalt (III) complex as the metal element to the amount of the bis (acetylacetonato) copper (II) complex as the metal element is 60/40 to 40 / 60, and the total amount of the tris (acetylacetonato) cobalt (III) complex and the bis (acetylacetonato) copper (II) complex as metal elements is 100 parts by weight of the rubber component, 0.15 to 0.40 parts by weight,
The rubber composition characterized by the above-mentioned.