JPH0345098B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber composition having three components as raw rubber components: natural rubber or polyisoprene rubber, polybutadiene rubber with a specific structure, and styrene-butadiene copolymer rubber with a specific structure. The vulcanization recovery in the process is improved, the processability is good, and the vulcanized product provides a rubber composition with excellent physical properties such as abrasion resistance and tensile strength. Raw material rubber used in vulcanized rubber products such as automobile tires, anti-vibration rubber, and footwear includes:
There are two types of rubber: natural rubber and synthetic rubber. Of these, natural rubber has better processability, green strength, adhesion, tensile strength, heat generation properties, etc. than various synthetic rubbers, and as a result of advances in science and technology, many synthetic rubbers have been developed. Even today, it is still used in many areas of rubber products. However, the disadvantages of natural rubber are that the abrasion resistance of the vulcanizate is poor;
During vulcanization, physical factors such as ``cure reversion'', which tends to cause unevenness in the vulcanized state, and natural rubber's production volume and price, compared to synthetic rubber, are affected by factors such as weather. This is because they are easily influenced by the market and are prone to supply concerns. Polyisoprene rubber, which was developed to replace natural rubber, is similar to natural rubber in terms of its molecular structure, but it is not as good as natural rubber in terms of green properties, adhesiveness, etc. In addition, although various other synthetic rubbers have various physical properties, most of them are not as good as natural rubber in terms of the balance of various physical properties. In addition, many attempts have been made to blend synthetic rubber with natural rubber in order to improve the above-mentioned disadvantages of natural rubber. For example, blending polybutadiene rubber with natural rubber has improved wear resistance. . However, little effort has been made to improve vulcanization recovery while retaining the above-mentioned characteristics of natural rubber. Under such circumstances, the inventors of the present invention have conducted intensive studies to improve a rubber composition in which natural rubber or polyisoprene rubber is blended with polybutadiene rubber and styrene-butadiene copolymer rubber, and as a result, they have arrived at the present invention. (A-1) Component: 20 to 75% by weight of natural rubber and/or polyisoprene (B-1) Component: 15 to 60% by weight of polybutadiene having a vinyl bond content of 35 to 60% (C-1 ) Ingredients: Styrene content is 5-35% by weight
and the amount of vinyl bonds in the butadiene moiety is 1 to
25% styrene-butadiene copolymer 10~
A conjugated diene rubber composition containing 50% by weight of three components as a raw material rubber, and a vulcanizing rubber composition containing (D) a reinforcing agent and (E) a vulcanizing agent in the raw material rubber. The present invention will be described in detail below. Component (A-1) of the present invention comprises natural rubber and/or
or polyisoprene rubber, preferably at least 30% by weight of the component (A-1) is natural rubber. The natural rubber used in the present invention has a polyisoprene skeleton, and is a raw material rubber obtained by concentrating and refining the sap of the Hevea tree and other plants. Furthermore, the polyisoprene rubber used in the present invention is
It is a rubber-like synthetic rubber obtained by polymerizing isoprene in an inert hydrocarbon solvent using a Ziegler catalyst or a lithium catalyst, and generally contains 85% or more of cis-1,4 bonds. , those with a number average molecular weight of about 100,000 to 1,000,000 are used. In the present invention, component (A-1) is used in a composition of 20 to 75% by weight, preferably 30 to 70% by weight of the raw rubber. If the amount is less than 20% by weight, the tensile strength, heat generation property, etc. of the resulting composition will be problematic, while if it exceeds 75% by weight, vulcanization is likely to occur. Next, the polybutadiene used as component (B-1) of the present invention is rubber-like and has a vinyl bond content of 35% or more and less than 60%. If the vinyl bond content is less than 35%, the effect of improving vulcanization recovery is insufficient, while if it is more than 60%, wear resistance becomes a problem. The polybutadiene component (B-1) may be a polymer in which the amount of vinyl bonds is uniform along the molecular chain, a polymer in which the amount of vinyl bonds varies along the molecular chain, or a polymer in which the amount of vinyl bonds is different along the molecular chain. Any polymer in which a polymer block exists can be used. The number average molecular weight of the polybutadiene component (B-1) is preferably 50,000 to 400,000, more preferably
The range is from 75,000 to 300,000, and the molecular weight distribution is preferably from 1.1 to 4.0. Component (B-1) is used in a range of 15 to 60% by weight, preferably 20 to 50% by weight in the raw rubber,
If it is less than 15% by weight, the effect of improving vulcanization recovery is slight, while if it exceeds 60% by weight, tensile strength and abrasion resistance will be poor. Next, the styrene content of the styrene-butadiene copolymer used as component (C-1) of the composition of the present invention is 5 to 35% by weight, preferably 10 to 30% by weight.
Weight%. If the styrene content is less than 5% by weight, the processability and wet skid resistance of the composition will be poor, and if it exceeds 35% by weight, the composition will have poor abrasion resistance and rebound resilience. The amount of vinyl bonds in the butadiene moiety of the styrene-butadiene copolymer (C-1) is 1 to 25%,
Preferably it is 1 to 15%. Vinyl bond amount is 25%
If it exceeds , the wear resistance of the resulting composition will be poor.
Regarding the styrene-butadiene copolymer of component (C-1), the styrene in the copolymer is a polymer in which styrene is present uniformly along the molecular chain, a polymer in which the amount of styrene is increased along the molecular chain, or A copolymer with a high amount of styrene or a copolymer with one or more blocks consisting of polystyrene and a copolymer with a low amount of styrene or one or more blocks consisting of polybutadiene, etc. However, the amount of blocked styrene in the copolymer is preferably less than 5% by weight of the copolymer. The number average molecular weight of the styrene-butadiene copolymer as component (C-1) is preferably 50,000 to 400,000,
More preferably, the range is 75,000 to 350,000, and the molecular weight distribution (Mw/Mn) is preferably 1.1 to 4.0. (C-1) component is 10 to 50% by weight in the raw rubber,
It is preferably used in an amount of 15 to 40% by weight. Ten
If it is less than 50% by weight, the abrasion resistance of the resulting composition will be insufficient, while if it exceeds 50% by weight, re-vulcanization will easily occur. Furthermore, in the present invention, the styrene content of the mixed component (B-1) and (C-1) is 10 to 35% by weight, and the amount of vinyl bonds in the butadiene portion is 30 to 60%. It is preferable to use each component according to its structure and composition in order to balance the effect of improving vulcanization reversion, retention of abrasion resistance, and other properties of the resulting composition. The polybutadiene of the component (B-1), (C-
1) Any of the styrene-butadiene copolymers obtained by any manufacturing method may be used as the raw rubber component of the present invention as long as they meet the limiting conditions for each polymer. can. The polybutadiene used as component (B-1) is a polymer having a relatively large amount of vinyl bonds. As a typical manufacturing method, organic lithium such as n-butyllithium or sec-butyllithium or other alkali metal compound is used as a polymerization catalyst in an inert solvent such as hexane, cyclohexane, or benzene, and if necessary, As a co-catalyst component, an organic compound typified by an alkoxide such as potassium butoxide, an organic acid salt such as dodecylbenzene sulfonate, and sodium stearate is used as a compound that adjusts the amount of vinyl bond.
It is obtained by polymerizing monomer butadiene using a polar organic compound such as ether, polyether, tertiary amine, polyamine, thioether, hexamethylphosphortriamide, etc. The amount of vinyl bonds can be controlled by the amount of the polar organic compound added and the polymerization temperature. It is also possible to couple the polymer chain having an active end obtained by the above method with a polyfunctional compound such as silicon tetrachloride, tin tetrachloride, or a polyepoxy compound, or to add a branching agent such as divinylbenzene. Depending on the method of addition to the polymerization system, branched or radial copolymers can be obtained. Furthermore, in the polymerization method, various polymerization conditions such as adjusting the addition method of the monomer, changing the amount of the compound for adjusting the vinyl bond amount, the addition method, and the polymerization temperature in the middle of the polymerization reaction, It is possible to produce a copolymer in which the amount of vinyl bonds increases or decreases in the molecular chain, or has a block shape. In addition, in polymerization, acetylene, 1,2-butadiene, fluorene, 1
Various compounds such as primary amines and secondary amines can also be used. The polymerization process for obtaining the above polymers can be a batch process, a continuous process, or a combination thereof. In addition, as another production method, it is also possible to obtain it by a method using a Ziegler catalyst. The styrene-butadiene copolymer used as component (C-1) is a copolymer with a relatively small amount of vinyl bonds. A typical method for producing the copolymer used as component (C-1) is the same as the method for obtaining the butadiene copolymer as component (B-1), except that the amount of vinyl bonds is set to a predetermined amount. For this reason, a method is used in which the amount of polar organic compound added is reduced or polymerization is performed without using it. In addition, when copolymerizing with a lithium-based catalyst without using a polar organic compound, the difference in copolymerization reaction rate between styrene and butadiene tends to result in a copolymer with styrene in the form of blocks, so the amount of block styrene is In order to obtain a small amount of copolymer, it is desirable to adjust the method of adding monomers or to adopt a method such as adding a compound such as dodecylbenzenesulfonate that does not significantly increase the amount of vinyl bonds. In addition, even in a production method other than polymerization using a lithium catalyst, such as a method using an emulsion polymerization method, (C-
1) It is possible to obtain a styrene-butadiene copolymer to be used as component. Next, the characteristics of the composition of the present invention will be described. (1) Compared to compositions using natural rubber and/or polyisoprene as raw material rubber, vulcanization recovery is improved, and the resulting vulcanizate has a good relationship between abrasion resistance and wet skid resistance. be. (2) Abrasion resistance and tensile strength are improved compared to a composition in which the raw rubbers are the component (A-1) of the present invention and the polybutadiene component (B-1). (3) Restoration of vulcanization is improved compared to a composition in which the raw rubber is two components, component (A-1) of the present invention and styrene-butadiene copolymer as component (C-1). . The composition of the present invention includes the component (A-1), (B-
Component 1) and component (C-1) are used as raw rubber,
Various compounding agents are added to this, and it is put into practical use by being molded and vulcanized. The compounding agents added to the above rubber composition include:
Reinforcing agents, softeners, fillers, vulcanizing agents, vulcanization accelerators, vulcanization aids, colorants, flame retardants, lubricants, foaming agents,
There are other compounding agents, and these are appropriately selected and used depending on the intended use of the composition. Carbon black is a typical reinforcing agent, and various types of reinforcing agents with different particle sizes or structures are used that are obtained by various manufacturing methods, but carbon blacks such as ISAF, HAF, and FEF are used. Suitable for use mainly in tires. The amount of carbon black to be added is determined by taking into account the amount of process oil to be used if necessary, but the
10 to 150 parts by weight, preferably 40 to 150 parts by weight
100 parts by weight are used. The type and amount of carbon black added are appropriately adjusted depending on the intended use of the rubber composition, and two or more types may be used in combination. Other reinforcing agents used include inorganic reinforcing agents such as silica and activated calcium carbonate, high styrene resins, and phenol-formaldehyde resins. 1 to 100 parts by weight are used, preferably 5 to 50 parts by weight. Typical softeners added as needed include process oils, and various types such as paraffinic, naphthenic, and aromatic softeners are suitably used in rubber compositions, and are added to 100 parts by weight of raw rubber. Against 2
~100 parts by weight are used, preferably 5 to 70 parts by weight. It is also possible to use an oil-extended polymer in which process oil is added to the raw rubber in advance. Other softeners include liquid paraffin,
These include coal tar, fatty oil, and sub. A typical example of the vulcanizing agent is sulfur, which is used in an amount of 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, per 100 parts by weight of raw rubber. Other vulcanizates include sulfur compounds such as sulfur chloride, morpholine disulfide, and alkylphenol disulfide, and peroxides, which may be used alone or in combination with sulfur. There are a wide variety of vulcanization accelerators,
These are used in an amount of 0.01 to 5 parts by weight per 100 parts by weight of raw rubber, and two or more types may be used in combination. Typical vulcanization accelerators include guanidine-based, aldehyde-amine and aldehyde-ammonia-based, thiazole-based, imidazoline-based, thiourea-based, dothiuram-based, dithiocarbamate-based, xanthate-based, and mixed accelerators. As a vulcanization aid, metal oxides such as zinc oxide,
There are fatty acid compounds such as stearic acid, amines, etc., and these are 0.1% per 100 parts by weight of raw rubber.
~10 parts by weight are used. Typical anti-aging agents or antioxidants added as needed are amine-based, phenol-based, phosphorus-based, sulfur-based, etc., and these are 0.001 to 10 parts by weight per 100 parts by weight of raw rubber. They may be added, and two or more types may be used in combination. In addition, scorch inhibitors added as needed include phthalic anhydride, salicylic acid, N-nitroso-diphenylamine, etc. Tackifiers include coumaron-indene resin, terpene-phenol resin, rosin ester, etc. Examples include calcium carbonate, clay, talc, and aluminum hydroxide. Furthermore, various other compounding agents may be used as necessary. The rubber composition of the present invention is produced by mixing raw rubber and various compounding agents using various mixing devices generally used for mixing rubber compositions, such as open rolls, Banbury mixers, kneaders, and extruders. Then, after being molded into the desired shape, it is vulcanized. The rubber composition of the present invention is suitably used for various automobile tires, belts, hoses, industrial goods such as anti-vibration rubber, footwear, daily necessities, construction materials, and various other uses by taking advantage of its characteristics. Examples are shown below, but these are intended to explain the present invention more specifically, and are not intended to limit the scope of the present invention. Reference example Polybutadiene and styrene used as component (B-1) and component (C-1) in the present invention
Examples of typical polymerization methods for polymers other than commercially available butadiene copolymers are shown below. Polymerization of Γ sample B-b [used as component (B-1)] Using a polymerization reactor with an internal volume of 40 mm equipped with a stirrer and a jacket, n-hexane was added to the reactor.
18.2 kg, butadiene 4.6 kg, diethylene glycol dimethyl ether 5.0 g, and n-butyl lithium 2.0 g were added, and the reactor internal temperature was maintained at 50 to 75°C, polymerization was continued for 1.5 hours. After adding 0.5 parts by weight of di-tert-butyl-P-chloresole, the solvent was removed to obtain sample B-b. The analytical values of this sample are shown in Table 2. Note that the microstructure was calculated by measuring the spectrum using an infrared spectrophotometer and using Morero's method. In addition, when sample B-b was analyzed by GPC, the weight average molecular weight (Mw) was 254,000, the number average molecular weight (Mn) was 178,000, and Mw/Mn = 1.43.
It was hot. In addition, GPC is Shimadzu LC-
Type 1 was used, the detector was a differential refractometer, the solvent was tetrahydrofuran, and the column was HSG-50.
60, 70, and one each were measured at a temperature of 40°C. The analytical values of other (B-1) components are shown in Table 2. Polymerization of Γ Sample Ca [used as component (C-1)] Using the same polymerization reactor as that used to obtain Sample B-b, 18.2 kg of cyclohexane, 3.45 kg of butadiene, 1.15 kg of styrene, and diethylene glycol were added to the reactor. Add 6.0 g of dimethyl ether and 3.0 g of n-butyl lithium and polymerize for 1 hour while maintaining the internal temperature of the reactor at 50 to 70°C. After the polymerization is complete, add 3.0 g of silicon tetrachloride to the polymer solution and perform a coupling reaction. Ta. Then, after adding 0.5 parts by weight of di-tert-butyl-P-cresol per 100 parts of polymer, the solvent was removed to obtain sample Ca. The analytical values of sample Ca are shown in Table 3. Also, Mw=276000, Mn=158000, Mw/
Mn=1.75. Polymerization of Γ sample C-f Using one polymerization reactor with an internal volume of 10 equipped with a stirrer and a jacket, the internal temperature of the polymerization reactor was set at 94 to 98°C.
26g/min of butadiene and 6.5g/min of styrene as monomers were supplied from the bottom of the reactor.
min, n-hexane as solvent 130g/min,
2.4 Tetrahydrofuran as a polar compound
The polymerization reaction was started by feeding 0.038 g of n-butyllithium as a catalyst per 100 g of monomer using a metering pump, and the polymer solution was continuously drawn out from the top of the reactor. After reaching a steady state, 0.5 parts by weight of di-tert-butyl-P-cresol per 100 parts by weight of the polymer was added to the obtained polymer solution, and the hexane solvent was removed. The analytical values of the obtained polymer (sample Cf) are shown in Table 3. In addition, in the analysis by GPC, sample C-f has Mw=338000, Mn=
148000, Mw/Mn=2.28. Table 3 also shows the analytical values of the styrene-butadiene copolymer used as the other component (C-1). The styrene content and the microstructure of the butadiene moiety of the styrene-butadiene copolymer were calculated by Hampton's method by measuring the spectrum using an infrared spectrophotometer.

【table】

【table】

[Table] Example 1 (A-1) Natural rubber (sample A-a) as the component,
The polybutadiene rubber shown in Table 2 was used as the component (B-1), the styrene-butadiene copolymer rubber shown in Table 3 was used as the component (C-1), and the composition shown in Table 5 was used as the raw rubber component. These were mixed using a Banbury mixer. After molding, the resulting compound was press-vulcanized at 140°C, and its physical properties were measured. The results are shown in Table 5. The results shown in Table 5 will be described below. As shown in Table 5, the compositions of Examples had less vulcanization reversion, and the relationship between abrasion resistance and wet skid resistance was better than that of Comparative Examples. On the other hand, each of the comparative examples outside the scope of the present invention has problems in recovery from vulcanization, tensile strength, and the like. Table 4 Raw material rubber 100 parts by weight Aromatic process oil 5 ISAF grade carbon black 45 Stearic acid 2 Zinc oxide 4 Anti-aging agent B ^*1 1 Vulcanization accelerator CZ ^*2 1 Sulfur 1.7 *1 Diphenylamine Reactant of and acetone *2 N-cyclohexylbenzothiazole sulfenamide

【table】

【table】

Claims (1)

[Claims] 1 (A-1) Component: 20 to 75% by weight of natural rubber and/or polyisoprene (B-1) Component: 15 to 60% by weight of polybutadiene having a vinyl bond content of 35% to 60% % (C-1) Component: Styrene content is 5-35% by weight
and the amount of vinyl bonds in the butadiene moiety is 1 to
25% styrene-butadiene copolymer 10~
A conjugated diene rubber composition containing 50% by weight of three components as raw rubber. 2 Claims: The polymer composition obtained by mixing component (B-1) and component (C-1) has a styrene content of 10 to 35% by weight and a vinyl bond content of the butadiene portion of 30 to 60%. The conjugated diene rubber composition according to item 1. 3 (A-1) Component: 20-75% by weight of natural rubber and/or polyisoprene (B-1) Component: 15-60% by weight of polybutadiene with a vinyl bond content of 35% or more and less than 60% (C-1) Ingredients: Styrene content 5-35% by weight
and the amount of vinyl bonds in the butadiene moiety is 1 to
25% styrene-butadiene copolymer 10~
A rubber composition for vulcanization comprising 50% by weight of three components as a raw rubber, and the raw rubber further comprising a component (D): a reinforcing agent and a component (E): a vulcanizing agent.