JPS6142641B2 - - Google Patents

Abstract

PURPOSE:To secure longer distance of running at puncture and also to improve comfortableness to ride by forming a semicircular-sectional annular elastic reinforcement with weight of a constant ratio to the weight of tire from polybutadiene polymer, rubber and carbon black. CONSTITUTION:A semicircular-sectional annular elastic reinforcement 5 with weight 15-30% to that of a tire is formed from a composition obtainable through compounding 4-10pts.wt. of organic vulcanizing agent as sulfur content and 40- 150pts.wt. of carbon black to 100pts.wt. of that for which 20-95pts.wt. of polybutadiene polymer with a content of 1,2-structure at 75wt% or more and a crystallinity at 15-75% and 5-80pts.wt. of rubber like natural rubber are blended. It is then provided inside both sides 3 or on the inside covering from both the sides to a shoulder part. Bend resistance is improved by specifying characteristic and compounding ratio of butadiene polymer, and a satisfactory reinforcing effect is obtainable through forming the tire semicircularly in section under regulating the weight, thus improving runing performance at puncture.

Description

[Detailed description of the invention]

The present invention relates to a pneumatic tire, and more particularly to a pneumatic safety tire that includes an annular elastic reinforcement on the inner surface of the side portion of the tire or on the inner surface extending between the side portion and the shoulder portion. It has been a long-held dream of tire engineers to develop a tire that does not cause any problems when driving even when a pneumatic tire is punctured and its air pressure drops to almost zero. There has been a strong demand for such tires from the viewpoint of safety. As a typical example,
Many safety tires are known in which the side portions, shoulder portions, or both of the tire sides are reinforced.
For example, Japanese Patent Publication No. 45-40483, Japanese Patent Publication No. 50-12921, Japanese Patent Publication No. 49-20802, Japanese Patent Publication No. 49-70303, Japanese Patent Publication No. 49-116702, Japanese Patent Publication No. 50-59902,
No. 50-60905, No. 50-60906, No. 50-
Publication No. 60907, Publication No. 50-78003, Publication No. 50-111704
No. 50-121902, No. 50-138502, No. 51-20301, No. 51-64203, No. 51-64203, No. 51-20301, No. 51-64203, No.
Safety tires such as those described above are disclosed in Publication No. 51-69804 and the like. However, although many tires have been proposed, there are almost no cases of them being put into practical use because the reinforcement rubber does not have sufficient bending or heat resistance. . That is,
When the air pressure drops to zero, the load on the tire is borne by the side parts, so the rubber that reinforces the side parts needs to have a high compression modulus, but generally rubber has a high modulus. This has the disadvantage that the bending resistance is extremely reduced and heat generation is more likely to occur. Therefore, in order to meet the performance required of reinforcing rubber, the gauge of the reinforcing rubber must be made extremely thick without making the modulus of the reinforcing rubber too high.As a result, the weight of the tire increases and Not only did the ride comfort deteriorate significantly, but the heat generated was more likely to accumulate, and eventually the rubber was destroyed, making it impossible to drive. In view of the current situation, the present inventors have conducted extensive research with the aim of providing a pneumatic safety tire that can dramatically improve mileage even when the tire is punctured and provides good ride comfort even during normal driving. As a result, when a relatively large amount of sulfur is added to a polybutadiene polymer with a 1,2-structure content of 75% by weight or more and a crystallinity of 15 to 70%, the crystallinity of the vulcanizate decreases. It was confirmed that a vulcanized rubber exhibiting rubber elasticity with extremely high modulus and low heat build-up was obtained, and this vulcanized rubber could be used as a reinforcing material on the inner surface of the side portion of a tire or on the inner surface extending from the side portion to the shoulder portion. The present inventors have discovered that it is possible to provide a pneumatic safety tire that has never existed before, and have achieved the present invention. Therefore, the present invention includes a pair of left and right bead portions, a pair of side portions connected to each bead portion, and a tread portion spanning between both side portions, and further includes a pair of tread portions on the inner surfaces of both side portions or on the inner surface extending from the side portions to the shoulder portion. In a pneumatic tire equipped with an annular elastic reinforcement, the annular elastic reinforcement has a crescent-shaped cross section and is made of polybutadiene containing 75% by weight or more of a 1,2-structure and having a crystallinity of 15 to 70%. polymer 20
~95 parts by weight, natural rubber, polyisoprene rubber,
Styrene-butadiene copolymer rubber, cis-1.
For 100 parts by weight of a mixture consisting of 5 to 80 parts by weight of at least one rubber selected from 4-polybutadiene rubber, ethylene-propylene-diene terpolymer rubber, halogenated butyl rubber, and acrylonitrile-butadiene copolymer rubber. , 40 to 150 parts by weight of carbon black, sulfur and/or an organic vulcanizing agent containing sulfur, with a sulfur content of 4 to 10 parts by weight.
The present invention relates to a pneumatic safety tire which is composed of a rubber composition compounded in such a manner that the weight of the tire is 15 to 30% of the weight of the tire. In the present invention, "having a crescent-shaped cross section" is broadly understood and includes not only regular and irregular crescent-shaped cross sections, but also arcuate cross sections. The attached drawing shows a cross section of a pneumatic safety tire according to an example of the present invention. In the drawings, 1 is a tire, 2 is a tread portion, 3 is a side portion, 4 is a bead portion, and 5 is an annular elastic reinforcement. In the present invention, the content of 1/2-structure used in the reinforcing body is 75% or more and the crystallinity is 15 to 75%.
For example, the polybutadiene polymer of
Publication No. 32425, Publication No. 44-32426, Publication No. 45-40302
No. 46-18496, No. 46-38697, No. 46-38698, No. 46-38699, No. 46-38697, No. 46-38698, No. 46-38699,
It is manufactured by the method described in Japanese Patent No. 46-38700 or Japanese Patent No. 47-1226. Furthermore, if the content of the 1,2-structure in the polybutadiene polymer is less than 75%, the modulus required for the side reinforcement rubber cannot be obtained, and if the degree of crystallinity is less than 15%, the vulcanization cannot be obtained. The modulus of the material is too low to be practical, and if it exceeds 70%, the vulcanizate becomes too hard and has poor processability, making it difficult to blend with other polymers, and decreasing the flex resistance as shown below. It becomes difficult to improve. In the present invention, the reinforcing body includes 20 to 95 parts by weight of the above polybutadiene polymer, natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, cis-1,4-polybutadiene rubber, ethylene-propylene-diene copolymer rubber, etc. A blend of 5 to 80 parts by weight of at least one rubber selected from the original copolymer, halogenated butyl rubber, and acrylonitrile-butadiene copolymer rubber is used, but the amount of polybutadiene polymer is less than 20 parts by weight, i.e., a blend. If the amount of other rubber used in the blend exceeds 80 parts by weight, the modulus of the vulcanizate obtained will not be sufficient; It is not preferable because the elongation at break and strength at break of the product are insufficient for use as reinforcing rubber for safety tires. In the present invention, the sulfur and/or sulfur-containing organic vulcanizing agent used in the reinforcing body is blended in an amount of 4 to 10 parts by weight, preferably 5 to 8 parts by weight, based on 100 parts by weight of the above mixture. If the amount is less than 4 parts by weight, the degree of crystallinity of the vulcanizate will become too high and the modulus will rapidly decrease at high temperatures, which is undesirable. If it exceeds 10 parts by weight, the fracture strength will rapidly decrease, resulting in poor impact resistance. This is not preferable because the characteristics deteriorate. As the organic vulcanizing agent containing sulfur, 4,4'-dithiodimorpholine, alkylthiuram disulfide, and alkylphenol disulfide are preferably used. In the present invention, the reinforcing body is further blended with 40 to 150 parts by weight of carbon black per 100 parts by weight of the above mixture, but if it is less than 40 parts by weight, the effect of the blending is not shown, while if it exceeds 150 parts by weight This is not preferable because the workability deteriorates significantly. In addition, carbon black has an iodine adsorption amount of 90mg/
g or less, dibutyl phthalate oil absorption is 90ml/
A material weighing 100 g or more is more preferable from the viewpoint of heat generation and reinforcing properties. Further, in the present invention, vulcanization accelerators, anti-aging agents, softeners, etc. commonly used in the rubber industry can be appropriately blended into the reinforcing body, if necessary. In addition, in the present invention, the weight of the reinforcing body must be in the range of 15 to 30% of the tire weight, its cross-sectional shape is crescent-shaped, and the maximum thickness position of the reinforcing body is at the maximum width position of the tire. Alternatively, it is more preferable that the crescent shape be located at a position radially outward of the maximum width position of the tire. If the weight of the reinforcing body is less than 15% of the tire weight, the desired reinforcing effect cannot be obtained and the runflat performance in the event of a puncture will be extremely deteriorated, while if it is heavier than 30%, the heat generation property will decrease. Therefore, the runflat running performance is still insufficient. In addition, due to the recent demand for fuel savings from the viewpoint of resource and energy conservation, it has become necessary to remove the spare tire in order to reduce vehicle weight as much as possible. It weighs more than the original 5 tires, and there is no point in removing the spare tire. From this point of view, the weight of the reinforcing body is preferably 15 to 25% of the weight of the tire. Further, in the pneumatic safety tire of the present invention, the belt may be made of any tire such as a steel cord or a textile cord. The pneumatic safety tire of the present invention having the above configuration includes a rubber composition having high modulus and extremely excellent bending resistance and heat resistance on the inner surface of the side portion or the inner surface extending from the side portion to the shoulder portion. By arranging it in a specific shape, it has the advantage of dramatically increasing the distance that can be traveled even if a flat tire occurs, so it is extremely useful industrially. The invention will be illustrated with reference to the following examples. Example 1 Using the eight types of polyurethane polymers shown in Table 1 below, compounded rubber compositions each having the composition shown in Table 2 were prepared, and 2000 g of each obtained rubber composition was prepared.
An annular elastic reinforcement body with a crescent-shaped cross section was installed on the inner side of a pneumatic tire (weight 10.5 kg, steel belt) with a tire size of 185HR14 as shown in the diagram, and a speed of 80 km/h at an internal pressure of 0 kg/cm ² was provided. The vehicle was run at a certain speed, and the distance traveled until the tire broke (runflat travel) was determined. For reference, the elongation at break, strength at break measured according to JIS K6301, and HBU according to ASTM D623-67 for each rubber composition.
(Heat Bild Up) was evaluated. These experimental results are also listed in Table 2.

【table】

【table】

[Table] Sample of Table 1 from Table 1 and Table 2
It is clear that the pneumatic safety tires of the present invention using Nos. 3 to 7 are significantly superior in runflat performance compared to other control tires, as shown in Experiment Nos. 3 to 7 in Table 2. be. The microstructure analysis shown in Table 1 was carried out by the Morello method using infrared absorption spectra, and the tacticity of the 1,2-structure was analyzed by ¹³ C-NMR spectroscopy. The crystallinity was determined from the density at 20°C measured using a density gradient tube. Example 2 Using the polybutadiene polymer of Sample 4 shown in Table 1, various rubber compositions shown in Table 3 were prepared. These rubber compositions were evaluated using them as reinforcing bodies according to Example 1, and the obtained results are also listed in Table 3.

【table】

[Table] The reinforcement weight ratio shown in Table 3 is the tire size
For 185HR14 tires (weight 9.7Kg), when the internal pressure is 0Kg/ ^cm2 , the distance between the vehicle and the road surface is 97% of the distance between the vehicle and the road surface when the internal pressure is normal (1.7Kg/ ^cm2 ). This is the value obtained by multiplying the weight of the reinforcing body required to achieve this by the tire weight (9.7 kg) and multiplying it by 100. For runflat running, tires made under the above conditions were used at an internal pressure of 0 Kg/cm ² and a speed of 80 Km/h.
The vehicle was run under these conditions and the distance traveled until the tire broke was determined. In addition, in order to keep the thickness of the reinforcement body constant, the shoulder part heat generation temperature was set at 2000g/
Reinforced with real rubber, internal pressure 0Kg/cm ² , speed 80Km/h
The temperature of the shoulder part of the tire was determined after running for 30 minutes under these conditions. The rest is the same as in Example 1. As is clear from Table 3, the tires of the present invention shown in Experiment Nos. 11 to 14 were significantly superior to the control tires in Experiments 9, 10, and 15 to 17 in runflat running. Example 3 In the same manner as in Example 2, using the polybutadiene polymer of Sample 4, various rubber compositions having the compositions shown in Table 4 were prepared. These rubber compositions were used as reinforcing bodies and examined in accordance with Example 2.

【table】

[Table] As is clear from Table 4, the tires of the present invention shown in Experiment Nos. 19 to 21 are excellent in runflat running. Example 4 The rubber composition shown in Experiment No. 13 in Table 3 above was used as a reinforcing body, and the reinforcing weight was varied on the inner surface of the side part of a tire size 185HR14, and flat running was investigated for each tire. The results obtained are shown in Table 5 below.

[Table] As is clear from Table 5, the tires of the present invention shown in Experiments Nos. 24 to 27 were superior to the control tires in Experiments Nos. 23 and 28 in runflat running. Although not shown in the examples, the carbon black blended into the reinforcing body had an iodine adsorption amount of 90ml/
Dibutyl phthalate oil absorption amount is 90ml/100g or less
It has been found that using carbon black with a thickness of g or more is more effective, and that the reinforcing effect is further improved if the maximum thickness position of the reinforcing body is at the tire maximum width position or outside that position in the tire radial direction. Ta.

[Brief explanation of the drawing]

The accompanying drawing is a cross-sectional view of the pneumatic safety tire of the present invention. DESCRIPTION OF SYMBOLS 1... Tire, 2... Tread part, 3... Side part, 4... Bead part, 5... Annular elastic reinforcement body.

Claims (1)

[Scope of Claims] 1. Comprising a pair of left and right bead portions, a pair of side portions connected to each bead portion, and a tread portion extending between both side portions, and further extending from the inner surface of both side portions or from the side portion to the shoulder portion. In a pneumatic tire having a pair of annular elastic reinforcing bodies on the inner surface, the annular elastic reinforcing bodies have a crescent shape in cross section, and have a shape of 1.
2-Contains 75% by weight or more of the structure and has a crystallinity of 15
20-95 parts by weight of ~70% polybutadiene polymer, natural rubber, polyisoprene rubber, styrene-
At least one rubber selected from butadiene copolymer rubber, cis-1,4-polybutadiene rubber, ethylene-propylene-diene terpolymer rubber, halogenated butyl rubber, and acrylonitrile-butadiene copolymer rubber5-80 40 parts by weight of carbon black to 100 parts by weight of the mixture.
~150 parts by weight of sulfur and/or a sulfur-containing organic vulcanizing agent, the sulfur content is 4 to 10 parts by weight.
Moreover, the weight of the annular elastic reinforcement is 15% of the tire weight.
A pneumatic safety tire characterized by ~30%. 2. The pneumatic safety tire according to claim 1, wherein the annular elastic reinforcing body is blended with sulfur and/or an organic vulcanizing agent containing sulfur so that the sulfur content is 5 to 8 parts by weight. 3. The pneumatic safety tire according to claim 1, wherein the organic vulcanizing agent blended into the annular elastic reinforcement is 4,4'-dithiodimorpholine, alkylthiuram disulfide, or alkylphenol disulfide. . 4. The pneumatic safety tire according to claim 1, wherein the carbon black blended into the annular elastic reinforcement has an iodine adsorption amount of 90 mg/g or less and a dibutyl phthalate oil absorption amount of 90 ml/100 g or more. 5 The weight of the annular elastic reinforcement is 15 to 25 times the weight of the tire.
% of the pneumatic safety tire according to claim 1. 6. The pneumatic safety tire according to claim 1, wherein the annular elastic reinforcement has a crescent shape with a maximum thickness at the maximum width position of the tire. 7. The pneumatic safety tire according to claim 1, wherein the annular elastic reinforcing body has a crescent shape with a maximum thickness at a position radially outward from the tire maximum width position.