JPS58110306A - Radial tyre - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The rubber stock and rim cushion of the tire are the same (1
) A radial tire integrally formed with a rubber composition having the following composition and having excellent extrusion productivity and molding productivity.

Conventionally, the bead portion of a radial tire is provided with a rim cushion rubber in contact with the rim and a reinforcing rubber stock inside the rim cushion rubber.

FIG. 1 is a sectional view of a conventional radial tire. In the figure, 1 is a cap tread rubber, 2 is a sidewall rubber, 3 is a carcass, 4 is a rim cushion rubber, 5 is a reinforcing rubber stock, 6 is a bead wire, and 8 is a rim.

The rim cushion rubber 4 is made of rubber having a composition rich in flex rack properties and abrasion resistance, and constitutes the outer side of the tire in contact with the rim 8. The reinforcing rubber stock 5 is made of rubber having a high JIS spring hardness and is formed between the outside of the carcass and the rim cushion rubber 4.

However, when manufacturing such conventional radial tires, the productivity in the extrusion process and molding process was extremely low. The reason for this is (2) the problem that the accuracy of simultaneous extrusion of the side wall rubber, rim cushion rubber, and reinforcing rubber stock is not good when extruding the three. In other words, when performing three-party extrusion,
Inadequate setting positions, air pockets, etc. occur, which is unfavorable in terms of tire uniformity, vulcanization failure, and tire performance. Therefore, it is necessary to separate the extrusion of the rim cushion rubber and reinforcing rubber stock from the extrusion of only the sidewall rubber.

Furthermore, in the molding process, first, the pre-touched rim cushion rubber reinforcing rubber stock described above is attached to the tire carcass body on the molding drum, and the tire is rotated.
It was then necessary to attach the sidewall extrusion onto the rim cushion rubber and reinforced Comstock pre-adhesive parts, and then rotate the tire.

Therefore, in the extrusion process and the molding process, the production of conventional tires is currently extremely inferior.

Therefore, there was an urgent need to develop a large-sized rim cushion rubber composition that combines the characteristics of a rim cushion rubber composition and a reinforcing rubber stock composition as a rubber compound composition. That is, there was a need for a rubber material that has both flex crack resistance and abrasion resistance, which are the characteristics of a rim cushion rubber composition, and JIS spring hardness, which is a characteristic of a reinforced rubber stock composition.

In order to meet such demands, the inventors of the present invention have conducted intensive studies and have arrived at the present invention.

Therefore, an object of the present invention is to provide a radial tire with excellent extrusion productivity and molding productivity.

That is, the radial tire of the present invention has cis-1,4-
A polymer obtained by block or graft polymerization of syndiotactic-1,2-polybutadiene to polybutadiene, and the microstructure of the polymer is a cis-1,4 structure75
~95% by weight, syndiotactic-1,2 structure 5-2
60 to 90 parts of carbon black having an average particle diameter of 50 mμ or less to 100 parts by weight of a rubber mixture consisting of 30 to 80 parts by weight of polybutadiene rubber and 20 to 70 parts by weight of other diene rubber. The gist thereof is that a rubber composition prepared by blending 2 to 10 parts by weight of a thermoplastic resin or a thermosetting resin is used as a tire reinforcing rubber stock and rim cushion rubber.

That is, the structure of the radial tire of the present invention is as shown in FIG.

FIG. 2 shows a sectional view of the radial tire of the present invention, and the numbers in the figure are the same as those in FIG. 1. However, in FIG. 2, the rim cushion rubber and reinforcing rubber stock are integrated, and a large rim cushion 7 is used.

The rubber composition constituting the large rim cushion 7 is a mixture of a specific rubber mixture A, a specific carbon black B, and a specific resin C, but it goes without saying that other necessary additives may be further blended. It is.

(5) Rubber mixture A is a mixture of a specific polybutadiene polymer a and other diene rubber b.

Polybutadiene polymer a is a polymer obtained by block or graft polymerization of syndiotactic-1,2-polybutadiene to cis-1,4-polybutadiene.
, 4-structure accounts for 75 to 95 parts by weight, and the syndiotactic-1,2 structure accounts for 5 to 20 parts by weight. Of course, this polybutadiene polymer a has trans-1,4 and syndio-1,2 structures.
1, 4 structure, etc. may be included. This polybutadiene polymer a can be produced by the method described in Japanese Patent Publication No. 4.9-176'66 and Japanese Patent Publication No. 4.9-17667. The syndiotactic-1,2 structure has a melting point of 200-210°C and a crystallinity of 65-75.
%. If the content of syndiotactic-1,2 structure is less than 5% by weight, the physical properties of cis-1,4-polybutadiene will be exhibited as they are, and if it exceeds 20% by weight, the 7-rex cracking property will decrease.

(6) Examples of the other diene rubber b include natural rubber, polyisoprene rubber, styrene-butadiene copolymer, or mixtures thereof.

30% by weight of polybutadiene polymer a in rubber mixture A
If it is less than 80% by weight, problems will arise in wear resistance, and if it exceeds 80% by weight, flex crack resistance will be poor.

Carbon black B needs to have an average particle diameter of 50 mμ or less. If it exceeds 50 mμ, the reinforcing property is low and the wear resistance is poor. Further, it is not necessary that all carbon particles have a diameter of 50 mμ, and if there is a distribution in particle size, it is sufficient that the average particle diameter is 50 mμ or less. The amount of carbon black B blended is 60 to 90 parts by weight based on 00 parts by weight of the rubber mixture Al, and if it is less than 60 parts by weight, the reinforcing properties are insufficient, and if it exceeds 90 parts by weight, it is unfavorable from the viewpoint of scratch resistance.

Furthermore, the resin C is a thermoplastic resin, a thermosetting resin, or a mixture thereof. Thermoplastic resins include, for example, coumaron resins, phenolic resins, terpene resins, petroleum-based hydrocarbon resins, rosin derivatives, or mixtures thereof, and thermosetting resins include, for example, novolak-type phenolic resins. , novolac type modified phenolic resin, etc.

The amount of resin C blended is 2 to 10 parts by weight based on 00 parts by weight of the rubber mixture, and if it is less than 2 parts by weight, J I
S (A) The spring hardness is not sufficient, and if it exceeds 10 parts by weight, it is unfavorable in terms of scratch resistance.

In addition to the above compounds, we also have curing agents for thermosetting resins, sulfur,
Vulcanization aids, anti-aging agents, process oils, etc. are usually blended in appropriate amounts.

Hereinafter, the present invention will be specifically explained with reference to Examples, and all proportions of ingredients in the Examples mean parts by weight. The mixing method, testing machine, and testing method were as follows.

(1) Mixing is carried out in a B-type Banbury (capacity 1.71), and the vulcanizing agent is mixed using 8 x 16 inch rolls.

(2) Vulcanization conditions: 160°C x 15 minutes vulcanization.

(3) JIS (A) Spring hardness is JIS
According to K-6301.

(4) The flex crack test measures the amount of growth after 100,000 cycles at 20% stroke and room temperature using a day mater crack tester.

(5) The abrasion test was conducted using a Gudrich Pico abrasion tester in accordance with ASTM-D-2228.

Examples 1 to 3 and Comparative Examples 1 to 3 Polybutadiene rubbers having various microstructures were produced, and their structural compositions are shown in Table 1.

Table 1 Next, a large rim cushion (FIG. 2, 7) was prepared using polybutadiene rubbers 1 to 6 shown in Table 1, and its composition and physical properties are shown in Table 2.

Table 2! (10) From the results in Tables 1 and 2, as the syndiotactic-1,2-structure increases, the JIS hardness increases, but the flex crack resistance depends on the syndiotactic-1,2-structure in balance with the JIS hardness. It can be seen that good results are obtained in the range of 5 to 20% by weight.

Examples 4 to 9 and Comparative Examples 4 to 9 In this example, when the blend ratio is different from that of other diene rubbers, when the average particle diameter and blending amount of carbon black are different, when the type and blending amount of resin are different, conduct a test,
The results are shown in Table 3.

(Margin below) The following can be seen from the results in Table 3.

If the amount of polyfridiene rubber used in the present invention exceeds 80 parts by weight, the JIS hardness will increase and the flex crack resistance will be poor (Comparative Example-4), whereas if it is less than 30 parts by weight, the wear resistance will be poor. . (Comparative Example-5) In Examples 4 and 5, the polyfuridiene rubber used in the present invention was 3
The amount is 0 to 80 parts by weight, the JIS hardness is moderately high, and the flex cracking property and abrasion resistance are excellent.

The average particle size of carbon black used in the present invention is 50
rl# or less, FEF (36771μ), ISA
Even when F (22 mμ) is used, good data is shown. The optimal blending amount is 60 to 90 parts by weight, but if it is less than 60 parts by weight, the wear resistance and J-S hardness will be poor. If it is 90 parts by weight or more, the flex cracking property will be significantly poor.

The resin used in the present invention may be either a thermoplastic resin or a thermosetting resin, and can be used sufficiently as long as it becomes hard after vulcanization. Even when modified rosin or petroleum resin is used, it satisfies JIS hardness, flex crack resistance, and wear resistance. If the resin amount is less than 2 parts by weight, the JIS hardness will not be satisfied, and if it exceeds 10 parts by weight, flex cracking properties will be poor.

Example 10 A conventional type tire shown in Fig. 1 (referred to as Tire B) and a tire of the present invention type shown in Fig. 2 (referred to as Tire A) were manufactured, and their productivity data and tire performance data were It is shown in Table 4.

In the productivity data for each process, the time required to manufacture a tire is expressed as an index with the conventional product (tire B) set as 100. In the durability test around the bead, the absolute value of the driving level and the details of the failure, and the value of the cornering power for the steering stability were compared to the conventional product (tire B).
It is expressed as an index as 00.

(Leaving space below) Table 4 Tire specifications, productivity, and tire performance (tire size 1553R13) 1) Physical properties of reinforcing rubber stock (Table 25 Same conditions as Table 3) JISHs: 92 Flex crack resistance = Sample failure pico at 10,000 cycles Amount of wear (XIOcc): 24 2) Index display when Tire B is set as 100. (From time study) The larger the index, the better the productivity.

3) Conditions Internal pressure: 2-2 kg/cFL2. speed:
81 km/hr) Load: Starts from 100% load of the actual vehicle, steps up by 15%/4 hours, and finally reaches 31 km/hr)
0% load.

4) Index display when Tire B is set as 100.

Conditions Internal pressure: 1-9kF & m2r Speed: 10km/h
r2 load = 70 kg The following can be seen from the results in Table 4.

Tire A, in which Example 1 was used as the large rim cushion rubber composition, was 25% superior to Tire B in the bead area durability test, and the failure occurred at the tread separation. Cornering power is also 4% better. Furthermore, in terms of productivity when manufacturing tires, compared to Tire B, it is 82% superior in extrusion productivity and 22% superior in molding productivity.

Tire A using Comparative Example 8 as a large rim cushion rubber composition has excellent productivity, but is inferior to Tire B in both durability around the bead and cornering power.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional tire, and FIG. 2 is a sectional view of a radial tire of the present invention. 1... Cap tread rubber, 2... Side wall rubber, 6... Carcass, 4... Rim cushion rubber, 5... Reinforcement rubber stock, 6... Bead wire, 7... Large size Rim cushion, 8... rim. Agent: Patent attorney Makoto Ogawa − Patent attorney: Ken Noguchi Patent attorney: Kazuhiko Saishita (17)

Claims (1)

[Claims] Syndiotactic to cis-1,4-polybutadiene
A polymer obtained by block or graft polymerization of 1,2-polybutadiene, and the microstructure of the polymer is cis-
1,4 structure 75-95% by weight, syndiotactic-1
, 2 structure 5-20% by weight polybutadiene rubber 30
~80 parts by weight of a rubber mixture consisting of 20 to 70 parts by weight of other diene rubber, 60 to 90 parts by weight of carbon black with an average particle size of 50 mμ or less, and a thermoplastic resin or thermosetting resin. 1. A radial tire characterized in that a rubber composition prepared by blending 2 to 10 parts by weight of a synthetic resin is used as a tire reinforcing rubber stock and as a rim cushion rubber.