JP2002205505A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire rim cushion that has less decrease of strength during heating, a tire carcass having high tire durability, an improved high temperature physical property (rigidity), and a high elasticity modulus, abrasion resistance, and a heat resistant setting property. SOLUTION: The tire carcass and/or the rim cushion of this pneumatic tire is made of (A) a short fiber/rubber complex in which nylon polymer containing montmorillonite is despersed as fine short fiber in a matrix composed of diene rubber and/or polyolefin, and the short fiber chemically bonds to the matrix, and (B) a rubber composition in which diene rubber is blended, and an amount of the nylon short fiber containing montmorillonite is 0.5 to 15 pts.wt. to entire rubber component of 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire, in which a carcass cord compound and / or a rim cushion compound is blended with fine staple fibers of a montmorillonite-containing nylon polymer, and particularly heat-resistant and durable. And a pneumatic tire having improved heat resistance setability and the like.

[0002]

2. Description of the Related Art A technique for improving the steering stability and durability of a pneumatic tire by using a rubber composition in which a polyamide short fiber is chemically bonded to a diene rubber is used in a tire carcass part of a pneumatic tire. 9-136 Kaihei
No. 995, and a composition in which natural rubber and / or polyisoprene rubber and polyamide short fibers are dispersed in a polyolefin matrix and chemically bonded to each other in a rim cushion portion of a pneumatic tire. Japanese Patent Application Laid-Open No. 9-59430 proposes a technique for improving the heat resistance of the rim cushion portion by using the compounded rubber composition. However, at present, even better tire members are required for the tire carcass portion and the rim cushion portion.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide each of the above-mentioned tire members which is superior in various performances, workability and the like to the above-mentioned prior art.

[0004]

According to the present invention, (A)
A short fiber / rubber composite in which a nylon polymer containing montmorillonite is dispersed as fine short fibers in a matrix composed of a diene rubber and / or a polyolefin, and the short fibers are chemically bonded to the matrix. And (B) a diene rubber, and
A pneumatic tire having a tire carcass part and / or a rim cushion part provided with a rubber composition in which the amount of short fibers of the montmorillonite-containing nylon polymer is 0.5 to 15 parts by weight based on 100 parts by weight of a total rubber component. You.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, nylon short fibers containing montmorillonite are used as carcass rubbers and / or rim cushion rubbers for tires in place of the polyamide short fibers used in the above-mentioned prior art. It is characterized by using a rubber composition obtained by dispersing as fine short fibers in a matrix composed of rubber and / or polyolefin and forming a short fiber / rubber composite chemically bonded thereto, and blending this with a diene rubber. Have.

[0006] Nylon containing montmorillonite has a higher strength retention when heated compared to current nylon. For this reason, the rubber composition containing the short fibers has high rigidity when heated, and when compounded into carcass rubber of a pneumatic tire, a decrease in strength when heated is suppressed, and the durability of the tire is improved. In addition, since the short fibers have high strength when heated, the physical properties (rigidity) of the rubber composition containing the short fibers at high temperatures can be improved as compared with the conventional short fibers, making them ideal for rubber compositions for rim cushions. It is possible to obtain a rubber composition having a high elastic modulus, excellent abrasion resistance, excellent heat setting properties, and excellent workability.

According to the present invention, as described above, the rubber composition of the tire carcass and / or the rim cushion does not contain the montmorillonite-containing nylon alone, but includes a diene rubber and / or a polyolefin matrix. The montmorillonite-containing nylon is dispersed in the diene rubber as a short fiber / rubber composite in a state of being chemically bonded to the matrix, so that the montmorillonite-containing nylon short fiber is contained in the rubber composition. Since it is well dispersed and chemically bonded to rubber, the affinity between the short fibers and the polymer is high, and the above-mentioned properties of the montmorillonite-containing nylon are sufficiently exhibited.

In the present invention, the term "montmorillonite-containing nylon" refers to a layered silicate montmorillonite that is uniformly dispersed at a molecular level in nylon.
The montmorillonite-containing nylon short fiber / rubber composite used in the present invention may be, for example, (a) polyolefin 10
0 parts by weight, (b) 10 to 400 parts by weight of a diene rubber and (c) 10 to 400 parts by weight of nylon containing montmorillonite were mixed with an initial condensate of a phenol formaldehyde resin or a silane coupling agent acting as a chemical binder. By adding 0.1 to 5.5 parts by weight per 100 parts by weight of the total of (a), (b) and (c), kneading, extruding, and stretching or rolling at a temperature lower than the melting point of nylon, It can be obtained by dispersing nylon containing montmorillonite as fine fibers in a matrix of polyolefin and diene rubber and chemically bonding them.

The diene rubber used to obtain the montmorillonite-containing nylon short fiber / rubber composite may be any diene rubber conventionally compounded in tire carcass or rim cushions. Examples of the polyolefin include polyethylene, polypropylene, polyethylethylene, polydimethylethylene, polystyrene, and the like. In addition, examples of the precondensate of the phenol formaldehyde resin used as the chemical binder include an initial condensate of a resol type or novolak type phenol formaldehyde resin. Of these, an initial condensate of novolak-type phenol-formaldehyde resin (novolak) is preferable, and an initial condensate of novolak-type phenol-formaldehyde, an initial condensate of novolak-type lactam-bisphenol F-formaldehyde, and an initial condensate of novolak-type styrenated phenol-phenol-formaldehyde. Condensates and the like can be suitably used.

According to the present invention, the nylon short fiber / rubber composite containing montmorillonite (A) is blended with the diene rubber (B) constituting the carcass rubber or the rim cushion rubber. The amount of the short fiber in the nylon short fiber / rubber composite containing montmorillonite is equal to the total rubber component (including the rubber component contained in the composite).
It is necessary to mix them in an amount of 0.5 to 15 parts by weight with respect to 0 parts by weight. If the blending amount of the short fibers is less than 0.5 part by weight, a sufficient reinforcing effect cannot be obtained, and if it exceeds 15 parts by weight, workability deteriorates. A suitable amount is 3 to 12 parts by weight.

The diene rubber to be added to the rubber composition of the present invention in addition to the above-mentioned montmorillonite-containing nylon short fiber / rubber composite (A) includes natural rubber, polyisoprene rubber, polybutadiene rubber, and styrene / butadiene. Any diene rubber conventionally used widely as a tire rubber, such as a polymer rubber, can be used. A component and B
The mixing ratio with the components is not particularly limited, but preferably (A) :( B) = 1.5: 100 to 45: 100.

The rubber composition used in the tire carcass part and / or rim cushion part of the present invention contains, in addition to the essential components (A) and (B), a reinforcing agent such as carbon black, sulfur, and vulcanization. Accelerators, anti-aging agents, fillers, softeners, various compounding agents and additives commonly used for tires such as plasticizers can be compounded,
Such a composition can be produced by vulcanization by a general method. The compounding amounts of these compounding agents and additives can also be made general amounts.

[0013]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Example 1, Standard Example 1 and Comparative Examples 1-2 According to the contents (parts by weight) shown in Table I below, components other than sulfur and the vulcanization accelerator were added in a 1.7 liter Banbury mixer for 5 minutes. After mixing, the mixture was mixed with sulfur and a vulcanization accelerator and kneaded with an 8-inch test kneading roll machine for 4 minutes to obtain a rubber composition used for a tire carcass portion. Test pieces were prepared by press-vulcanizing these rubber compositions at 160 ° C. for 15 minutes, and various tests were carried out to measure the vulcanized properties. Further, a pneumatic radial tire having a tire size of 165SR13 (4.5 × 13 rim) was manufactured using the rubber composition, and its durability was evaluated. The results are shown in Table I.

[0015]

[Table 1]

Each test (300% modulus, tensile strength, elongation, JIS hardness and dynamic elastic modulus (20 ° C., 60 ° C.)) of the vulcanization properties in Table I was carried out in accordance with JIS K6301. . The durability test is based on JISD432
After the completion of the high-speed durability test of 0, the test was performed at an acceleration of 10 km / h every 30 minutes until the tire was broken. Result is,
The running distance of the standard example 1 was set to 100 and displayed as an index.

The following commercial products were used for the components used in Table I, and the short fibers A and B were blended and prepared to have the following composition. NR: STR-20 (TECK BEE HANG) SBR: Nipol 1502 (Nihon Zeon) BR: Nipol 1220 (Nihon Zeon) Antioxidant: Nocrack 224 (Ouchi Shinko Chemical) Carbon black: Seast V (Tokai Carbon) Vulcanization acceleration Agent: Noxeller CZ (Ouchi Shinko Chemical) Short fiber A: Nylon short fiber composition (6-nylon / polyethylene / NR = 87.5 / 75/100) Short fiber B: Nylon short fiber / rubber composite with montmorillonite ( Nylon / polyethylene / NR with montmorillonite = 87.5 / 75/100)

According to the results shown in Table I, those of Example 1 of the present invention show a significant improvement in dynamic elastic modulus (60 ° C.) at high temperature and durability.

Examples 2 and 3, Standard Example 2 and Comparative Examples 3 to
6 According to the composition (parts by weight) shown in Table II below, components other than sulfur and the vulcanization accelerator were mixed with a 1.7 liter Banbury mixer for 5 minutes, and sulfur and the vulcanization accelerator were added to the mixture. The mixture was mixed and kneaded with an 8-inch test kneading roll machine for 4 minutes to obtain a rubber composition used for a tire rim cushion portion. Using a part of this rubber composition, the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the unvulcanized material was measured. The remaining rubber composition was press-vulcanized at 160 ° C. for 15 minutes to prepare test pieces, and various tests of vulcanization properties were performed.

[0020]

[Table 2]

The Mooney viscosity of the unvulcanized material in Table II is J
According to ISK6300, Mooney viscosity ML at 100 ° C.
_{1 + 4} was measured. In addition, each test for vulcanization properties (dynamic elastic modulus (20 ° C., 100 ° C.), hardness, rebound resilience, and compression set (70 ° C. × 22H) were all performed in accordance with JIS K6301. The wear resistance test was performed using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) at a temperature of 20 ° C.
The wear loss was measured under the condition of a slip ratio of 40%, and the standard example 2
And 100 as an index.

The following commercial products were used for the components used in Table II, and the short fibers 1 to 3 were blended and prepared to have the following composition. NR: STR-20 (TECK BEE HANG) BR: Nipol 1220 (Nippon Zeon) Carbon black: Seast KH (Tokai Carbon) Antioxidant: Antigen 6C (Sumitomo Chemical Industries) Vulcanization accelerator: Noxeller NS-F (Ouchi) Shinko Chemical) Short fiber 1: SBR master batch of cellulose short fiber (fiber / SBR = 2/1) Short fiber 2: Nylon short fiber composition (6-nylon / polyethylene / NR = 87.5 / 75/100, Ube) Kosan S
HP-40) Short fiber 3: Nylon short fiber containing montmorillonite / rubber composite (nylon with montmorillonite / polyethylene / NR = 87.5 / 75/100)

According to the results in Table II, Examples 2 to 2 of the present invention are shown.
In the case of No. 3, a significant improvement effect on the elastic modulus and the permanent compression set was observed without any significant decrease in other physical properties.

[0024]

As described above, by blending nylon staple fiber containing montmorillonite into the tire carcass rubber according to the present invention, a decrease in strength when heated is suppressed,
In addition, a tire carcass having high tire durability can be obtained, and the high-temperature physical properties (rigidity) are improved by blending the montmorillonite-containing nylon short fiber of the present invention with the rim cushion rubber, and the body is worn at a high elastic modulus. Rim cushion excellent in heat resistance and heat resistance setting property can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 77/00 C08L 77/00

Claims (1)

[Claims] 1. A nylon polymer containing montmorillonite is dispersed as fine short fibers in a matrix comprising (A) a diene rubber and / or a polyolefin, and the short fibers are chemically bonded to the matrix. And the amount of short fibers of the montmorillonite-containing nylon polymer is 0.5 to 15 parts by weight based on 100 parts by weight of the total rubber component. A pneumatic tire having a tire carcass portion and / or a rim cushion portion made of a rubber composition.