JPS63203404A - Radial tire - Google Patents

Abstract

PURPOSE:To effectively lower rolling resistance only, by applying specific denatured polyisoprene rubber to a carcass covering rubber constituent and/or a base tread rubber constituent without changing a cap tread rubber material. CONSTITUTION:A radial tire is provided with a toroidal carcass ply layer 2 whose both symmetrical sides are engaged with a bead wire 1, and the crown part 3 is reinforced with a belt layer 4. In this case, as a carcass covering rubber constituent and/or a base tread layer 5, these materials stated below are used. That is, a 15-100pts.wt. of alkaline metal added polyisoprene rubber or denatured polyisoprene rubber reacting this denatured one with a bensophenone system compound and the others, and a rubber compound consisting of a 0-85pts.wt. of another diene system rubber are used. With this constitution, only rolling resistance is lowered without lowering braking performance on a wet road and fundamental performance of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radial tire, and particularly to a pneumatic radial tire that reduces internal friction loss of tire constituent materials caused by tire deformation during running.

[Prior art]

Traditionally, due to society's desire to save energy, how to reduce fuel consumption for automobiles has become an important issue, and from an engine perspective,
Improvements to the chassis and other aspects are actively underway. Regarding tires, research is also being conducted to reduce the rolling resistance of tires. In order to reduce the rolling resistance of tires, it is effective to reduce internal friction loss caused by degeneration during tire running. One way to do this is to use a rubber material with low internal friction loss for the tire cap tread material, and there is no doubt that this method is a very effective means for lowering rolling resistance.

However, the magnitude of the internal friction loss of the rubber influences the basic characteristics of the tire such as braking performance, handling performance, riding comfort performance, and wear resistance performance.

In addition, as mentioned above, lowering the internal friction loss of the rubber material for camping treads in order to reduce tire rolling resistance will extend the braking distance during braking when driving at high speeds or on wet roads, improving steering stability. In general, the wear resistance decreases, resulting in poor riding comfort and a decrease in wear resistance.

Recently, it has been announced that by using high vinyl type polybutadiene rubber or styrene-butadiene copolymer rubber, it is possible to obtain a tread rubber composition that has good braking performance on wet road surfaces and low rolling resistance. (Unexamined Japanese Patent Publication No. 56-127
651, JP 56-127652, JP 55-104343, JP 56-10693
No. 7, JP-A-60-72941, etc.). However, even in this case, there is a drawback that the wear resistance is greatly deteriorated.

As mentioned above, in order to obtain a low rolling resistance tire, a rubber material that occupies the largest volume per tire and has a large internal friction loss is generally used to improve the various tire characteristics mentioned above. Attempts have been made to reduce the internal friction loss of rubber compositions for cap treads, but for the reasons mentioned above, some of the tire properties are currently sacrificed.

[Purpose of the invention]

The present invention was made in view of the above-mentioned current situation, and
A pneumatic product that maintains low rolling resistance by applying a specific modified polyisoprene rubber to the rubber composition for carcass cord coating and/or the rubber composition for base tread without changing the rubber material for Camp Trend. The purpose is to provide radial tires.

[Structure of the invention]

Therefore, the present invention provides alkali metal-added polyisoprene rubber or alkaline earth metal-added polyisoprene rubber,
15 to 100 parts by weight of modified polyisoprene rubber reacted with a benzophenone compound, a compound having a -CN< bond in the molecule (M is O or S), or an isocyanate compound and 0 to 85 parts by weight of other diene rubber The gist of the invention is a radial tire characterized in that a rubber compound consisting of the following is used as a rubber composition for covering a carcass cord and/or a rubber composition for a base tread. In addition, the present invention has an iodine adsorption amount of 15 to 90 μ/g and a nitrogen specific surface area of 15 to 90
rd/g, D B P oil absorption is 40 to 120 mf/
The gist of the invention is a radial tire according to claim 1, which contains 35 to 70 parts by weight of 100 g of carbon black.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory half-sectional view in the meridian direction of an example of the radial tire of the present invention.

The radial tire of the present invention will be explained with reference to the drawings. The radial tire of the present invention shown in FIG.
This is a radial tire with a toroidal carcass ply layer 2 anchored to the carcass ply layer 2 and a crown portion 3 of this carcass ply layer 2 reinforced with a belt layer 4, and a base tread layer that does not come into contact with the road surface even after the tire life ends ( Undertrend layer) 5, a radial tire consisting of one inner liner layer 6 and one outer liner layer 7, in which a rubber composition using modified polyisoprene rubber is used for both or at least one of the carcass ply layer 2 and the base tread layer 5. .

Modified polyisoprene rubber is alkali metal-added polyisoprene rubber or alkaline earth metal-added polyisoprene rubber, and a benzophenone-based compound, a compound having a -CN< bond in the molecule (M is 0 or S), or an isocyanate-based compound. It is a reaction.

This modified polyisoprene is produced by polymerizing isoprene using an alkali metal-based catalyst or alkaline earth metal catalyst commonly used in solution polymerization, and an alkali metal or alkaline earth metal is bonded to the end of the molecular chain. Polyisoprene rubber obtained by reacting polyisoprene rubber with benzophenones or thiobenzophenones, which has four atomic groups represented by the following general formula via carbon-carbon bonds at the end of the molecular chain. .

(In the formula, R9 and R2 are hydrogen or a substituent, M is 0 or S
, m and n each represent an integer) The benzophenones and thiobenzophenones used here include, for example, 4,4'-bis(dimethylamino)-benzophenone, 4,4-bis(diethylamino)-benzophenone,
4.45bis(dibutylamino)-benzophenone,
4゜4-diaminobenzophenone, 4-dimethylaminobenzophenone, etc., and their corresponding thiobenzophenones. Among these, benzophenone and thiobenzophenone having at least one amino group, alkylamino group or dialkylamino group on one or both benzene rings are particularly preferred. Benzophenones and thiobenzophenones having at least one alkoxy group, halogen or hydrocarbon residue as a substituent in addition to the above amino group, such as 4,4-jethoxybenzophenone, 3,4-dimethoxybenzophenone, 4
．． 4-dimethylbenzophenone, 3,3-dicyclobenzophenone, 4-methyl-4'-methoxybenzophenone, 2.2',3.3-tetramethylbenzophenone,
2.2-Cyclobenzophenones and the like and the corresponding thiobenzophenones can also be used, but also unsubstituted benzophenones and thiobenzophenones.

In addition, at the end of the molecular chain, there is a -C-N bond in the molecule (however,
(M in the formula represents an O atom or an S atom) is introduced. These compounds include amide compounds such as formamide, acetamide, aminoacetamide, N,N-dimethylaminoacetamide, acrylamide, nicotinamide, phthalic acid amide, oxamide, 2-furancarboxylic acid amide, and quinoline-2-carboxylic acid amide; Imide compounds such as succinimide, maleimide, N-methylmaleimide, phthalimide, ε-caprolactam, N-methyl-ε-caprolactam, 2-pyrrolidone, 2-piperidone, N-methyl-2-pyrrolidone, N
- Lactam compounds such as methyl-2-piperidone and 2-quinoline, urea compounds such as N,N-dimethylurea, N,N-diethylurea, N,N-dimethyl-N',N'-diphenylurea, Isocyanuric acid derivatives such as methyl carbamate and isocyanuric acid.

Examples of the isocyanate compounds include 2°4-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and hexamethylene diisocyanate.

Other diene rubbers to be blended with this modified polyisoprene rubber include natural rubber, synthetic polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, polychloroprene rubber, polybentenamer, polyoctenamer, butadiene-isoprene rubber, etc. polymerized rubber,
Any one of styrene-isoprene copolymer rubber or the like may be used, or two or more types may be used.

Among these, natural rubber, synthetic polyisoprene rubber, styrene-butadiene copolymer rubber, and polybutadiene rubber are particularly preferred.

Regarding the blending ratio of modified polyisoprene rubber and other diene rubber, the use of modified polyisoprene rubber alone is most effective, and it is necessary to blend at least 15 parts by weight of modified polyisoprene rubber. If it is less than 15 parts by weight, the rate at which heat generation is improved is small, and the tire's rolling resistance, ie, fuel efficiency, is not improved.

The carbon black used here to blend into the rubber is
Iodine adsorption amount is 15-90g/g, nitrogen specific surface area is 15
-90rrf/g, preferably in the range of 20-80. If the iodine adsorption amount and nitrogen specific surface area are less than 15, the tensile strength is low, which is a problem. Also, 90
If it exceeds this value, the tensile strength is high, but the heat generation is large and it cannot be used. DBP oil absorption is 40-120aif/100g
, preferably in the range of 60 to 100 mf/g. If it is smaller than 40 m/100 g, the dispersion will be poor and the modulus will be too low.

Exceeding 120 aJ/100g generates too much heat.

The blending amount of carbon black is 35 to 70 parts by weight, preferably 40 to 60 parts by weight. If it is less than 35 parts by weight, the breaking strength will be too low, and if it exceeds 70 parts by weight, the heat generation property will deteriorate. In addition to the above-mentioned compounding agents, fillers, anti-aging agents, vulcanization aids, vulcanizing agents, vulcanization accelerators, process oils, etc. which are commonly used in the rubber industry may be appropriately compounded.

Examples and comparative examples are shown below.

Examples and Comparative Examples Rubber compositions for carcass cord coating and rubber compositions for base tread were prepared according to the formulations (parts by weight) shown in Table 1 below, and tires were made as trial tires. The size of the tires used in the prototype was 165 SR13. The transfer resistance was measured by an indoor rotation test, and the results are expressed as an index in Table 2. In addition, the braking distance on a wet road surface was actually measured using an actual vehicle, and the results were expressed as an index and similarly shown in Table 2. Each evaluation method is as follows.

Destructive characteristics〉 According to JIS K 6301.

(tan δ) Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, the strain rate was 10 ± 2% during elongation deformation, the frequency was 20 Hz, and the temperature was 20.
Measurement was carried out under the condition of 60°C.

<Rolling resistance> Tire air pressure 1.9 kg/aJ, load 420 kg on a 1707 m diameter drum testing machine for FMVSS 109 testing.

Measured at a speed of 40.60.80km/hr,! It is expressed as an index with lhl tires set as 100. Therefore, the smaller the index, the lower the resistance and the better the fuel efficiency.

〈Braking distance index〉 When tires are installed on a passenger car, 60 km/h on a wet road surface is achieved.
Measure the braking distance from hr and set the Nll tire to 100
The index is displayed as . Therefore, the larger the index, the better.

(Margins below this page) From the above results, it was found that tires with a carcass cord coating rubber composition using modified polyisoprene rubber 2. 3. 5. Arashi 6. Circle 7. Number 8 is the tire NIL of the comparative example.
Compared to 1 and N14, transfer resistance is lower and fuel efficiency is clearly improved.

Furthermore, tires in which the rubber composition of the present invention is used not only as a carcass cord coating but also as an undertread rubber composition.
L7 has the lowest transfer resistance, with transfer resistance improved by about 10%. Further, tire N11B using the rubber composition of the present invention only as the undertread rubber composition also has improved rolling resistance.
In both cases, the braking distance on a wet road surface is at the same level as the comparative example.

〔Effect of the invention〕

As described above, the radial tire of the present invention has a reduced rolling resistance without any deterioration in the braking performance on wet roads or the basic performance of the tire, and is widely used not only as a general fuel-efficient tire but also as a high-performance tire. Also available.

[Brief explanation of the drawing]

FIG. 1 is an explanatory half-sectional view in the meridian direction of an example of the radial tire of the present invention. 1... Bead wire, 2... Carcass ply layer,
3... Crown portion, 4... Belt layer, 5... Under. Tread layer, 6... one layer of inner liner, 7... one layer of outer liner.

Claims (1)

[Claims] 1. A benzophenone compound in alkali metal-added polyisoprene rubber or alkaline earth metal-added polyisoprene rubber, a compound having a ▲ mathematical formula, chemical formula, table, etc. in the molecule ▼ bond (M is O or S), or modified polyisoprene rubber 1 reacted with an isocyanate compound
A radial tire characterized in that a rubber compound comprising 5 to 100 parts by weight of another diene rubber and 0 to 85 parts by weight of another diene rubber is used as a rubber composition for covering a carcass cord and/or a rubber composition for a base tread. 2. Iodine adsorption amount is 15-90mg/g, nitrogen specific surface area is 15-90m^2/g, DBP oil absorption is 40-120
The radial tire according to claim 1, which contains 35 to 70 parts by weight of carbon black in an amount of ml/100g.