JPS6255539B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to tire rubber compounding compositions comprising hydrogenated polybutadiene rubber containing moderate 1,2 bonding units, in particular having improved high tensile strength, high tensile stress, high hardness, The present invention relates to a rubber compound composition suitable for tire materials, which has small temperature dependence of these properties and has improved physical properties at high temperatures, particularly high hardness, low heat generation, and high wet skid resistance. Conventionally, the performance requirements for automobile tires include safety, economy, ride comfort, etc. In recent years, the requirements for safety and economy have become even stricter, and tire materials have also become more demanding. There is a need for something with the above characteristics. These requirements are common to all tire components whose main component is rubber, such as the tread, carcass, sidewall, bead, and belt, and their specific performance is high tensile strength, high tensile stress, and It has low temperature dependence of stress, low temperature dependence of hardness, adhesion, abrasion resistance, low heat generation, and high skid resistance. In particular, with the shift to radial tires, tire rubber materials with high tensile strength, high tensile stress,
A material with high hardness is desired. Especially recently,
It is a strong tire material that combines low heat generation, which is an indicator of low rolling characteristics from the perspective of fuel efficiency, and high wet and skid resistance for safety, as well as high tensile strength, high tensile stress, and high hardness. It is requested. As a method to provide high tensile strength, high tensile stress, and high hardness, and to satisfy low heat generation and high wet skid resistance, a method using a hydrogenated polybutadiene containing a high 1,4 bond unit (specially Kaisho
54-124047). According to this method, the tensile stress, tensile strength, and hardness at room temperature (25℃) increase, but for example, the hardness at 70℃ decreases significantly compared to the value at room temperature, and compared to non-hydrogenated polybutadiene. , it is difficult to say that sufficient improvements have been made. When a car is running, tires generate heat due to hysteresis loss, causing their temperature to rise. The temperature reached at equilibrium during driving varies depending on the type of car and tire, but for example, it rises to about 70°C [Automobile Technology, Vol. 33, No. 5, pp. 300-307, (1979)].
Therefore, the performance of high tensile strength, high tensile stress, and high hardness required for rubber materials for tires is performance at high temperatures (e.g., 70°C) in actual use, and conventional rubber materials that meet these required characteristics at high temperatures No rubber material for tires has been found. Also, as a future direction,
Furthermore, it seems that good performance at high temperatures is required. Furthermore, recently, there has been a trend toward lighter tires as a way to reduce fuel consumption, and tires with high hardness and
Rubber materials for tire treads and carcass that provide high tensile stress and high tensile strength are highly desired. Therefore, the present inventors have discovered that the present invention has high tensile strength, high tensile stress, and high hardness, has low temperature dependence of tensile strength, tensile stress, and hardness, and has high tensile strength at high temperatures.
In order to find a rubber material for tires that has high tensile stress and high hardness, low heat generation, and high wet and skid resistance, we surprisingly found that a hydrogenated medium 1,2 bond The present inventors have discovered that a rubber compound composition containing a polybutadiene unit as one component has the above-mentioned performance superior to a hydrogenated low 1,2 bond unit polybutadiene compound and is suitable for this purpose, and has thus arrived at the present invention. That is, the object of the present invention is to have improved high tensile strength, high tensile stress, and high hardness, have small temperature dependence of tensile strength, tensile stress, and hardness, and have excellent physical properties, especially hardness, at high temperatures. Another object of the present invention is to provide a rubber compound composition for tires which has reduced heat build-up and improved wet skid resistance. The rubber compound composition of the present invention has 1,2 bonding units.
25-90% hydrogenation of polybutadiene containing 30-60% and weight average molecular weight of 100000-1000000 () 10-80% by weight and bound styrene amount 15-30
At least one rubber selected from styrene-butadiene copolymer rubber (wt%), natural rubber, polybutadiene rubber containing 80% or more of 1,4 bond units, and polyisoprene rubber containing 90% or more of cis 1,4 bond units () 20 to 90% by weight. The hydrogenated polybutadiene used in the present invention is
Polybutadiene containing 30 to 60% of 1,2 bond units is hydrogenated, and the hydrogenation rate expressed as mole % in terms of butadiene monomer units is 25 to 90%. When polybutadiene with high 1,4 bond units and few 1,2 bond units is hydrogenated, hydrogenation occurs in the main chain of the polymer, producing ethylene chains, giving it resin-like properties and resulting in high tensile strength and high tensile strength. Becomes to have stress and high hardness. However, since it has strong resin-like properties, the temperature dependence of the above performance is large, and as a result, the tensile strength, tensile stress, and hardness at high temperatures are particularly improved compared to non-hydrogenated high 1,4 bond unit polybutadiene. Not done. Therefore, it is necessary that the polybutadiene has 30% or more of 1,2 bond units. In addition, polybutadiene with high 1,2 bond units has low tensile strength, tensile stress, and hardness without hydrogenation, and the above properties are not improved even by hydrogenation, and the 1,2 bond unit content of polybutadiene to be hydrogenated is low. requires 30-60%. The weight average molecular weight of polybutadiene is 100,000~
Must be in the range 1000000. If the weight average molecular weight is less than 100,000, the resulting hydrogenated product will not have sufficient tensile strength or stress;
If it exceeds 1,000,000, the processability of the resulting hydrogenated product is equally reduced. The hydrogenation rate needs to be 25-90%. If the hydrogenation rate is less than 25%, the hydrogenation effect will be poor, while if it exceeds 90%, the resin-like properties will increase and the processability as a rubber will decrease. The preferred hydrogenation rate is 35-80%. The hydrogenated 1,2 bond unit polybutadiene used in the present invention is obtained by a known polymerization method using a polar compound such as an ether or amine as a 1,2 bond unit regulator and an organolithium compound as a polymerization catalyst. Using a solution of two bonding units polybutadiene,
This solution is obtained by carrying out a hydrogenation reaction under hydrogen pressure in the presence of a catalyst. As a hydrogenation reaction catalyst, a homogeneous catalyst is a combination of an organic nickel compound or organic cobalt compound such as nickel naphthenate or cobalt naphthenate, and an organic aluminum compound such as triethylaluminum or tributylaluminum or an organic lithium compound such as n-butyllithium. catalyst,
Heterogeneous catalysts such as palladium-carbon and reduced nickel can be used. The () component rubber used in the present invention is a styrene-butadiene copolymer rubber containing 15 to 30% by weight of bound styrene obtained by emulsion polymerization or solution polymerization using an organic alkali metal catalyst, natural rubber, 1 obtained by solution polymerization of butadiene using a transition metal catalyst or an organic alkali metal catalyst.
It is at least one type of rubber selected from polybutadiene rubber having 80% or more of 4-bond units and polyisoprene obtained by solution polymerizing isoprene using a transition metal catalyst or an organic alkali metal catalyst. The amount used is 20 to 90% by weight, and if it is less than 20% by weight, the tensile stress, tensile strength, which is the object of the present invention,
Physical properties such as hardness are not improved, and if it exceeds 90% by weight, wear resistance decreases, which is not preferable. The rubber compounding compositions containing the hydrogenated 1,2 bond unit polybutadiene used in the present invention contain compounding agents used in the rubber industry, such as carbon black, process oils, sulfur, vulcanization accelerators, vulcanization auxiliaries, etc. Agents, anti-aging agents, etc. can be added as appropriate. There is no particular restriction on the method of processing and vulcanizing the rubber compound composition obtained in this way, and after mixing and compounding the above-mentioned components well using a mixer such as a roll or Banbury, a vulcanizing press or a vulcanizing kettle is used. It can be vulcanized using conventional methods. The tire rubber composition containing 1,2 bond unit polybutadiene during hydrogenation of the present invention has high tensile strength,
It has high tensile stress and high hardness, and the temperature dependence of these properties is small.As a result, it exhibits improved high tensile strength, high tensile stress, and high hardness at high temperatures, and has low heat generation and high wet skid resistance. It can be suitably used in various parts of tires, and can improve tire performance such as fuel efficiency, handling stability, and high-speed stability. Next, the present invention will be specifically explained with reference to Examples. Examples 1 to 3, Comparative Examples 1 to 6 Polybutadiene with 1,2 bond units during hydrogenation was produced as follows. First, 100g of 1,2-bond unit polybutadiene (obtained by solution polymerization using an organolithium compound as a polymerization catalyst and tetrahydrofuran as a 1,2-bond unit regulator) was put into a 5% autoclave as a 5% by weight toluene solution. Ta. As a catalyst for the hydrogenation reaction, a 5% by weight toluene solution of polybutadiene was mixed with 3 mmol of butadiene monomer,
A mixture of 3 mmol of nickel naphthenate and 9 mmol of triethylaluminum was aged in a nitrogen stream for 20 minutes and added to the autoclave. Next, hydrogen was injected into the autoclave to a hydrogen pressure of 4 kg/cm ² G, and the pressure was increased to 0.5 to 2 at 70 to 80°C.
The hydrogenation reaction was carried out for an hour. The hydrogenated polymer solution is poured into methanol and solidified,
After drying under reduced pressure, polybutadiene with 1,2 bond units was obtained during hydrogenation. Using the hydrogenated 1,2-bond unit polybutadiene produced by the above method and having a hydrogenation rate of 35, 55, and 75%, it was blended according to the formulation shown in Table 1, and then vulcanized at 145°C for 35 minutes. The physical properties of the vulcanizate
Examples 1 to 3 are shown in the table. Table 2 shows comparative examples 1 to 6 of 1,2 bond unit polybutadiene (comparative example 3,
4) Hydrogenation rate of 35 with weight average molecular weight less than 100,000
% medium 1,2 bond unit polybutadiene (Comparative Example 6), and low 1,2 bond unit polybutadiene with hydrogenation rates of 0% and 35% (Comparative Example 1,
2), and the physical properties of a blend containing polybutadiene with a high 1,2 bond unit (Comparative Example 5) with a hydrogenation rate of 35% are shown together with Examples. Comparative Examples 3 and 4 and Example 1 shown in Table 2,
From the results of 2 and 3, it is clear that during hydrogenation, the composition containing 1,2-bond polybutadiene significantly improves tensile stress, tensile strength, and hardness as the hydrogenation rate increases, and has low heat generation due to wetness and
It can be seen that the skid resistance increases. On the other hand, in a blended composition of hydrogenated polybutadiene with 1,2 bond units at a hydrogenation rate of less than 25%, the characteristics obtained by the present invention are hardly observed. Although not shown in Table 2, in the case of polybutadiene with 1,2 bond units during hydrogenation at a hydrogenation rate of over 90%, it became resinous and was difficult to be vulcanized in the usual manner. Furthermore, as shown in Comparative Examples 1 and 2, the blended composition using the hydrogenated product of low 1,2 bond unit polybutadiene was compared to the blended composition of the hydrogenated 1,2 bond unit polybutadiene of the present invention. The temperature dependence of tensile stress, tensile strength, and hardness is large, and the decrease in hardness is particularly noticeable at high temperatures, and no improvement from general-purpose low 1,2 bond unit polybutadiene compositions is observed at temperatures of 70°C or higher. It turns out that there isn't. On the other hand, it can be seen from Comparative Example 5 that the blended composition of hydrogenated polybutadiene with high 1,2 bond units has low tensile stress, low tensile strength, and low hardness, and hardly has the characteristics of the present invention. From Comparative Example 6, the weight average molecular weight is
Hydrogenated 1,2 bond unit polybutadiene compositions with a weight average molecular weight of less than 100,000 cannot obtain sufficient tensile stress and tensile strength, and are not shown; In the case of polybutadiene with two bond units, the processability was extremely poor and physical properties could not be evaluated. As described above, the hydrogenated 1,2 bond unit polybutadiene composition of the present invention has improved high tensile strength, high tensile stress, and high hardness, and the temperature dependence of these physical properties is small. It can be seen that it provides high tensile strength, high tensile stress, and high hardness at high temperatures, and has low heat generation and high wet skid resistance. Example 4, Comparative Examples 7 and 8 Vulcanized products compounded and vulcanized under the same conditions as in Example 1, with only the ratio of 1, 2 bond unit polybutadiene and natural rubber changed during hydrogenation using the formulation shown in Table 1. The physical properties are shown in Table 3. From the results of Example 4 and Comparative Example 7, the characteristics of the present invention cannot be achieved if the mixing ratio of polybutadiene with 1,2 bond units during hydrogenation is less than 10% by weight. On the other hand, from the results of Comparative Example 8, when the mixing ratio of polybutadiene with 1,2 bond units exceeds 80% by weight during hydrogenation, the wear resistance decreases. Therefore, the mixing ratio of 1,2 bond unit polybutadiene during hydrogenation is 10 to 80% by weight.
It turns out that is preferable. Table 1 Part by weight Hydrogenated polybutadiene 50 Natural rubber 50 Zinc 3 Stearic acid 2 Sulfur 1.5 Vulcanization accelerator (Noxel NS ^* ) 0.9 Carbon black (HAF) 50 Aromatic process oil 10 * Shinko Ouchi N-t-butyl-2-benzothiazolesulfenamide manufactured by Kagaku Co., Ltd.

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Claims (1)

[Scope of Claims] 1. Hydrogenated product () 10-10 containing 30-60% of 1,2 bond units and having a hydrogenation rate of 25-90% of polybutadiene with a weight average molecular weight of 100,000-1,000,000.
Styrene-butadiene copolymer rubber with 80% by weight and 15-30% by weight of bound styrene, natural rubber, 1,4
At least one rubber selected from polybutadiene rubber containing 80% or more of bonding units and polyisoprene rubber containing 90% or more of cis-1,4 bonding units (20)
~90% by weight of a rubber compound composition for tires. 2. The rubber compound composition for tires according to claim 1, which contains a hydrogenated material having a hydrogenation rate of 35 to 80%.