JPH0717787B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic tire, and particularly to a large tire, a small tire, a motorcycle tire, an aircraft tire, etc. in which an inner liner rubber or a ply coating rubber is arranged. , For pneumatic tires of all kinds.

(Prior Art) In the molding step of manufacturing a green tire by combining the respective members of the tire, it is necessary that the green modulus of each member is high to some extent. For example, in the case of the inner liner of a passenger car radial tire, if the green modulus is low, the inner liner will expand unevenly when the green case is expanded during the molding process, and a thin part will be generated from that when unvulcanized. There is a problem such as cracks in.

Further, when the green tire is vulcanized, it is also necessary that the Mooney viscosity of each member is high to some extent. For example,
In the case of ply-coated rubber for passenger car radial tires, if the Mooney viscosity is low, the rubber may be unnecessarily rubbed during the vulcanization process, which may cause cords to come out. Further, in the case of a high oil type tread rubber, when the Mooney viscosity is too low, problems such as adhesion to the mixer and poor dispersion of the compounding agent occur when kneading with the Banbury mixer.

Therefore, conventionally, in order to increase the green modulus or Mooney viscosity, generally, the blending amount of carbon black has been increased to achieve the object.

In addition, "green" means "unvulcanized" here.

(Problems of the prior art) However, when the amount of carbon black is increased to increase the green modulus and Mooney viscosity, other physical properties required for a tire member often deteriorate. For example, the increase in carbon in the tread member and the case member has a drawback that the resilience after vulcanization is reduced, resulting in deterioration of fuel efficiency due to an increase in rolling resistance, and deterioration of durability due to an increase in heat generation. Further, the increase of carbon in the inner liner member increases the storage elastic modulus E ′ after vulcanization, so that the cracking resistance is lowered, and there are problems such as fatigue cracking during running.

On the other hand, it is possible to increase the green modulus by using a commercially available plasticity adjusting agent such as Polyac (trade name, manufactured by DuPont), but these are not effective enough, and when used in a large amount, the level of the green modulus is increased. Became unstable and the physical properties after vulcanization changed in an unfavorable direction.

As described above, there has been no effective compounding method for increasing the green modulus of a tire member requiring a low storage elastic modulus E ′ or a high resilience after vulcanization.

Therefore, it is an object of the present invention to provide a pneumatic tire in which an inner liner rubber or a ply coating rubber is arranged in which the green modulus and the Mooney viscosity at the time of vulcanization of the green tire are increased and at the same time the above-mentioned drawbacks are improved. More specifically, the object of the present invention is to blend a chemical having a property of itself having a function of increasing the green modulus or Mooney viscosity and a function of lowering the storage elastic modulus E ′ and increasing resilience after vulcanization. As a result, a pneumatic tire having an inner liner rubber or a ply coating rubber arranged, which has both an increase in green modulus and Mooney viscosity, a decrease in storage elastic modulus E ′ after vulcanization, and an increase in resilience, is provided. Accordingly, a pneumatic tire having an inner liner rubber or a ply coating rubber having a much higher green modulus without changing physical properties such as storage elastic modulus E ′ and resilience in combination with an increase in carbon content is provided. Especially.

(Means for Solving Problems) As a result of extensively examining additives capable of achieving the above object from various angles, the present inventor found that a certain organotin compound can meet the above object. The present invention has been completed and the present invention has been completed.

That is, the present invention relates to a pneumatic tire in which an inner liner rubber or a ply coating rubber is arranged, which contains 0.1 to 5.0 parts by weight of an organotin compound with respect to 100 parts by weight of a diene rubber.

Examples of organotin compounds that can be used in the present invention include di-n-octyltin compounds, di-n-butyltin compounds, and di-methyltin compounds. The-n-
Examples of the octyltin compound include dioctyltin sulfide, dioctyltin mercapto, di-n-octyltin-S, S'-bis (isooctylmercaptoacetate), di-n-octyltin bis (isooctylglycolic acid ester) salt, There are di-n-octyltin maleate, di-n-octyltin maleate, di-n-octyltin laurate and the like. Also,
Examples of the n-butyltin compound include dibutyltin dilaurate, dibutyltin dimaleate, di-n-butyltin maleate ester salt, di-n-butyltin sulfide, poly (thiobis-n-butyltin sulfide), di-n-butyltin ester ester. There are rate carboxylate, dibutyltin maleate, monobutyltin mercaptide, dibutyltin mercapto, di-n-butyltin maleate mercapto and the like. Furthermore, examples of the dimethyltin compound include dimethyltin bis (octyl thioglycolate) and dimethyltin bis (isooctyl mercaptoacetate). Of these organotin compounds, dioctyltin sulfide, dibutyltin sulfide, dibutyltin malate, dibutyltin mercapto, dioctyltin mercapto, and dimethyltin bis (octyl thioglycolate) are particularly preferable.

The diene rubber to which such an organic tin compound is added is, for example, natural rubber, cis-1,4-polyisoprene rubber, styrene butadiene rubber, polybutadiene rubber, butyl rubber, halogenated butyl rubber such as chlorobutyl or brombutyl.

In the rubber composition of the present invention, a compounding agent used for usual rubber compounding, such as carbon black, a softening agent, sulfur, a vulcanization accelerator, zinc white, stearic acid, an antiaging agent, etc., may be added as necessary. It can be blended.

(Operation) The compounding amount of the organotin compound is 0.1 to 5.0 parts by weight, preferably 0.2 to 3.0 parts by weight, based on 100 parts by weight of the diene rubber. This is because if the compounding amount is less than 0.1 parts by weight, the increase in green modulus or Mooney viscosity is small, while if it exceeds 5.0 parts by weight, gelation of the rubber becomes remarkable and the processability deteriorates, which is not preferable. Is.

Therefore, the inner liner rubber and the ply coating rubber of the pneumatic tire of the present invention suitably act when the compounding amount is within the above range.

(Example) Next, this invention is demonstrated based on an Example.

Examples 1 to 6 and Comparative Example 1 Various rubber compositions for inner liner members were produced according to the compounding ratio (parts by weight) shown in Table 1 below.

For these rubber compositions, the green modulus and Mooney viscosity before vulcanization, and the storage elastic modulus E ′ and resilience after vulcanization were measured as follows.

B) Green modulus The sample was made into a ring shape and the 50% modulus was measured when this was pulled at 100 mm / min at 24 ° C.

(B) Mooney viscosity A Mooney viscometer (SMV-200, manufactured by Shimadzu Corporation) was used to measure the temperature at 130 ° C., and the result was displayed as a torque value (Moonie 4 minutes value) 4 minutes after the start of measurement.

C) Storage elasticity at 10 ° C. E ′ sample was made into a strip shape and subjected to a periodic elongation strain of 0.05%, and measured at 50 Hz.

D) Resilience 25 ° C using resilience tester (manufactured by Toyo Seiki Co., Ltd.)
It was measured at ± 2 ° C. The evaluation was performed using the restitution coefficient of a pendulum that was swung from an angle of 40 ° above the horizontal position (average value of 3 times after 3 shots).

The measurement results are also shown in Table 1.

Since each of the rubber compositions of Examples has a higher Mooney viscosity and a higher green modulus than the rubber composition of Comparative Example 1, the unvulcanized rubber tends to occur on the inner liner when the green case is expanded. Cracks could be suppressed, and the flow of rubber during vulcanization was optimized, and the flow of inner liner rubber between the carcass cords could be prevented. Further, after vulcanization, the resilience could be maintained at a high level, so that the fuel economy was excellent, and since the storage elastic modulus E ′ value could be lowered, the crack resistance was also excellent.

Furthermore, in Example 2, as a result of combining the increased amount of carbon black and the organotin compound, the storage elastic modulus E ′ and resilience after vulcanization were improved to the same level or higher as in Comparative Example 1, and the green modulus and Mooney were much higher. Since the viscosity was secured, the inner liner could be made thinner.

Examples 7 to 10 and Comparative Example 2 Various rubber compositions for ply coating rubber were produced according to the compounding ratio (parts by weight) shown in Table 2 below.

For these rubber compositions, the Mooney viscosity before vulcanization and the resilience after vulcanization were measured as described above.

The measurement results are also shown in Table 2.

Each of the compositions of the examples was able to increase the Mooney viscosity as compared with the composition of Comparative Example 2, and therefore, the cord was extruded due to rubber flow during vulcanization, that is, the carcass ply cord was exposed to the inner surface of the tire. Since it was possible to easily prevent this, and to increase the resilience after vulcanization, it was possible to improve fuel efficiency.

(Effects of the Invention) As described above, in the inner liner rubber and the ply coating rubber of the pneumatic tire of the present invention,
By blending a certain amount of an organotin compound,
It is possible to achieve both the increase in green modulus and Mooney viscosity when unvulcanized and the decrease in storage elastic modulus E ′ and increase in resilience after vulcanization.

Claims (2)

[Claims] 1. A pneumatic tire comprising an inner liner rubber or a ply coating rubber containing 0.1 to 5.0 parts by weight of an organotin compound based on 100 parts by weight of a diene rubber. 2. The pneumatic tire according to claim 1, wherein the organotin compound is dioctyltin sulfide, dibutyltin sulfide, dibutyltin malate, dioctyltin mercapto, dibutyltin mercapto or dimethyltin bis (octyl thioglycolate). .