JPS584611A - Tire - Google Patents

Abstract

PURPOSE:To improve the feeling of ride, by using a composite rubber material in which soft carbon and thermosetting phenol resin are blended. CONSTITUTION:The folded part of a carcass 3 is placed inside bead-reinforcing rubber 6 extending as a tongue to nearly the central part of a sidewall 2. A bead filler 4 and the bead-reinforcing rubber 6 are made of a composite rubber material which comprises 100pts.wt. of rubber, 55-95pts.wt. of soft carbon, 5-30pts.wt. of thermosetting phenol resin and a setting agent so that the total amount of the soft carbon and the thermosetting phenol resin is 60-100pts.wt. per 100pts.wt. of the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire using a high-hardness rubber composition with excellent processability, and more specifically, a tire comprising a rubber composition containing soft carbon, a phenolic thermosetting resin, and a curing agent. The present invention relates to a tire in which a high hardness rubber composition made of a rubber composition is used in the parts of the tire that require high rigidity.

Conventionally, the hardness of the rubber composition used in the above-mentioned parts of the tire has been increased by adding large amounts of compounding agents such as carbon black, sulfur, and vulcanization accelerators to the rubber. It is possible to increase the hardness of a rubber composition by blending a large amount of carbon black into rubber, for example, by increasing the hardness measured with a JIS spring type hardness tester (hereinafter abbreviated as JIS Hs) to 90 or higher. Although it is possible, this rubber composition
The rubber clumps, the power load on the Banbury mixer increases, and the state of wrapping on the roll is extremely poor, making it difficult to put it to practical use. Therefore, the hardness of the rubber is increased by adjusting the amount of carbon black to a practical level and adding large amounts of sulfur and a vulcanization accelerator. However, although this rubber composition has somewhat improved processability during mixing, due to the high sulfur content of the rubber composition, significant sulfur bloom occurs in the extrudate when the rubber composition is extruded. However, the generation of this plume reduces the productivity during tire molding or the quality of the product, and the hardness obtained with such rubber compositions is
IS Hs: Up to about 88.

Furthermore, in order to further increase the hardness of the rubber composition, it is also practiced to use a thermosetting resin in combination. In this case, the heat generated during mixing of the rubber composition promotes curing of the thermosetting resin, so the mixing processability is improved to some extent and the hardness JIS Hs:
A rubber composition of 90 or more is obtained. However, when a thermosetting resin is blended with carbon black (so-called hard carbon) with an average particle size of 20 to 30 mμ, although the mixing processability is considerably improved as described above, the viscosity of the rubber composition does not decrease, making it difficult to process by extrusion. There is no improvement in properties, and there are no drawbacks such as the extrudate being extremely difficult to handle during molding. That is, the average particle diameter is 20 to 307
A rubber composition containing 71μ carbon black and a thermosetting resin has an abnormally high rigidity when unvulcanized compared to the stiffness of a rubber composition that does not contain a thermosetting resin. Since the self-adhering ability, which is the essence of rubber, has been lost, the lamination and bending workability of the rubber composition will be significantly impaired, and the moldability of tires using extruded rubber compositions will be affected. This results in defects that reduce the quality of the tire.

On the other hand, in the bead structure of a conventional tire, as shown in Fig. 1, the tip 1 of the folded part of the carcass 6 is pulled up to the upper end of the curved sidewall part 2 of the tire, and there is a space between the carcass 3 main body and the folded part. It is equipped with relatively hard rubber (bead filler 4), which maintains steering stability. However, in this structure, the bead filler 4 is sandwiched between the carcass body and the folded part of the carcass, which significantly deteriorates the ride comfort, which is the reason why radial tires are said to have poor ride comfort. In order to improve this problem, as shown in FIG. Insufficient rigidity results in sacrificing the steering stability and durability of the tire.

Therefore, the purpose of the present invention is to provide a tire with improved ride comfort without impairing handling stability and durability.To this end, the inventors of the present invention have conducted extensive research and found that the rubber content is 100%. Based on the weight part, 55 to 95 parts by weight of soft carbon and 5 to 30 parts by weight of phenolic thermosetting resin and curing agent are blended, and the additional blending amount of soft carbon and phenolic thermosetting resin is 60 parts by weight. The rubber composition in the range of 100 parts by weight has a hardness JIS Ha of 92 or more and a Mooney viscosity of 6.
0 or less and green strength of 10 to 9/cIn2 or less, it is a rubber composition with extremely excellent processability in mixing, extrusion, etc., and has been found to be particularly effective as a tire bead filler or bead reinforcement rubber. Ta.

That is, the average particle diameter is 40 mμ or more, for example, 40 to 8
Soft carbon existing within the range of 0 mμ has a small reinforcing effect on rubber, so it has not been used for the purpose of obtaining high hardness.
By combining soft carbon with a diameter of 0 to 80171μ, a 7-el thermosetting resin, and a curing agent, the vulcanizate obtained by vulcanization has the elasticity and fracture properties (rupture strength, fracture elongation) unique to rubber. A rubber composition with high hardness can be obtained without impairing the hardness of the rubber composition, and the softening effect of the phenolic thermosetting resin due to the processing temperature during mixing and extrusion of the rubber composition, and the reduction in the viscosity of the rubber composition due to the soft carbon. The inventors have discovered that the viscosity of the rubber composition can be significantly lowered and the mixing, extrusion, and molding processability of the rubber composition can be significantly improved.

In addition, the present inventors have a bead reinforcing rubber disposed between the folded part of the carcass and the sidewall, and the bead reinforcing rubber is arranged in a tongue-like manner to approximately the center of the sidewall. It has been found that the above object can be achieved by using the above rubber composition for the bead filler and/or the bead reinforcing rubber in the bead structure.

Therefore, the present invention has been made based on these findings, and has a bead reinforcing rubber disposed between the folded part of the carcass and the sidewall, and the bead reinforcing rubber is applied almost to the sidewall. A tire that is arranged in a tongue-like manner to the center, and has a bead filler and/or
Or, the peed part reinforcing rubber is one or more of natural rubber, diene rubber, and diene copolymer rubber with a rubber content of 100.
55 to 95 parts by weight of soft, carbon,
5 to 30 parts by weight of a phenolic thermosetting resin and a curing agent, and the added amount of the soft carbon and the phenolic thermosetting resin is 60 to 100 parts by weight per 100 parts by weight of rubber.
It is characterized by being composed of a rubber composition blended in such a manner that the weight of the rubber composition is as follows.

Hereinafter, the configuration of the present invention will be explained in detail.

FIG. 3 is a cross-sectional view of the bead part of an example of the tire of the present invention. In order to improve durability, especially to prevent separation from occurring from the folded end 1 of the carcass 3, the folded part of the carcass 3 is placed inside the bead reinforcing rubber 6. The bead portion reinforcing rubber 6, which has a structure in which it is placed and a structure in which it is not provided, is arranged so as to extend in a tongue shape almost to the center of the sidewall 2, and the bead filler 4
and the bead portion reinforcing rubber 6 are made of the above rubber composition.

The rubber serving as the base of the rubber composition used in the present invention is preferably natural rubber, diene rubber, diene copolymer, or a rubber blended with any ratio of these rubbers, and more specifically, natural rubber, butadiene rubber, styrene rubber, etc. - Butadiene rubber and rubber blended with these rubbers in arbitrary proportions, which are sulfur vulcanizable, are preferably used.

The carbon black to be blended into this rubber includes FEF, GPF, SRF, FF, and HMF having an average particle diameter of 40 mμ or more, preferably within the range of 40 to 80 mμ.
.

There are APF, MPF, etc., and so-called soft carbon is used. When carbon black such as HAF with an average particle diameter of less than 40 mμ is used, although sufficiently satisfactory physical properties can be obtained in terms of hardness, Mooney viscosity and green strength are increased, and therefore processability is poor, which makes it impossible to achieve the goal of the present invention. However, in order to increase the reinforcing properties of the Bohm composition, it is possible to add a small amount without impairing processability. On the other hand, it is impossible for soft carbon with a hardness exceeding 100 mμ to obtain a hardness of JIS) (a: 92).
55 to 95 parts by weight relative to 0 parts by weight, more preferably 6 parts by weight
By blending 5 to 85 parts by weight, a rubber composition that achieves the object of the present invention can be obtained, and if it is less than 55 parts by weight, the hardness JIS Hs: 9, which is the object of the present invention.
If the amount exceeds 95 parts by weight, the Mooney viscosity and green strength will be too high, resulting in poor processability, especially mixing processability, and the object of the present invention will not be achieved.

Furthermore, as the phenolic thermosetting resin to be blended with these, resins that harden by heat, such as straight phenol resin, cresol-modified phenol resin, and cashew-modified phenol resin, are preferably used. The blending amount of the phenolic thermosetting resin is 5 parts by weight per 100 parts by weight of rubber.
~30 parts by weight, preferably 10-20 parts by weight, and 5
If the amount is less than part by weight, the hardness JISHs is the objective of the present invention:
92 or more cannot be obtained, and if more than 30 parts by weight is blended, the Mooney viscosity and green strength are too high and the processability is poor, making it impossible to put it to practical use from the viewpoint of moldability.

In addition, the added blending amount of soft carbon and phenolic thermosetting resin also needs to be considered in order to obtain the rubber composition used in the present invention, and the added blending amount of soft carbon and 7-enol thermosetting resin is 60 to 100 parts by weight, preferably 75 to 90 parts by weight per 100 parts by weight of rubber.
Rubber compositions that achieve the objectives of the invention can be obtained within a range of parts by weight. If the additional blending amount of both is less than 60 parts by weight, the hardness JISHs as the object of the present invention:
92 or higher, and if more than 100 parts by weight is added, the Mooney viscosity and green strength are too high and the object of the present invention cannot be achieved in terms of processability.

The curing agent used next is necessary for curing the phenolic thermosetting resin, and any curing agent that is commonly used for thermosetting may be used. For example, hexamethylenetetramine is a typical curing agent. If it is less than 0.1 part by weight per 100 parts by weight of rubber, the thermosetting reaction is difficult to occur.
Since the amount by weight or more is more than sufficient to cause a thermosetting reaction, 0.1 to 3 parts by weight is preferable.

In addition to the above compounding agents, fillers, anti-aging agents, softeners, vulcanization aids, tackifiers, etc., which are commonly used as compounding agents for rubber, may be added within a range that does not impair the hardness and processing characteristics of the rubber composition. It may also be suitable.

The rubber composition obtained in this way can be used as a vulcanized rubber with a hardness of JISHs: 92 or higher without impairing processability or moldability when unvulcanized. By arranging it in a tongue-like manner over the part that maintains the lateral rigidity of the tire, that is, approximately the center of the sidewall of the tire, it is possible to improve ride comfort without impairing the handling performance and durability of the tire. . This effect is particularly noticeable in radial tires, which have relatively low riding comfort.

In addition, this rubber composition has a hardness of JISH after vulcanization.
Despite the fact that s is 92 or more, the Mooney viscosity is 60 or less and the green strength is 10 kli' when unvulcanized.
/CrIL2 Since it has the following properties, the processability is significantly improved.

In other words, improving the mixing processability of this rubber composition reduces the power load on the Banbury mixer and leads to energy savings, while also providing good rubber cohesion, a good sheet surface, and improving extrusion processability. It maintains good self-adhesive ability and has a rubber average particle size of 20 to 30 m.
The biggest drawback of rubber compositions mainly composed of carbon black (so-called hard carbon), thermosetting resin, and curing agent is that the stiffness of unvulcanized rubber at room temperature is significantly reduced; The stiffness is far inferior to that of a rubber composition without a curable resin, and the workability of molding tires using the rubber extrudate of the present invention is significantly improved.

Hereinafter, the present invention will be explained based on examples, and the proportions of ingredients in the examples mean parts by weight.

Examples 1 to 4 Carbon black (FEF) with an average particle diameter of 40 to 45 mμ
) in the range of 50 to 100 parts by weight was made into a sheet and cured at 150°C for 15 minutes.
s was measured.

In addition, the plasticity of the unvulcanized rubber was measured using a Mooney viscometer, and a tensile test was conducted using an unvulcanized rubber composition punched out using a JIS No. 1 dumbbell. A measure of the stiffness of rubber during sulfurization (
green strength).

These results are shown in Table 1.

(The following is a blank space) Examples 5 to 7 Example 1 was prepared using each rubber composition shown in Table 2 in which cashew-modified cresol was varied within the range of 3 to 35 parts by weight.
It was carried out in the same way. The results are shown in Table 2.

(Left below) Cashew-modified cresol resin and average particle size 50-5
The experiment was carried out in the same manner as in Example 1 using each rubber composition shown in Table 3 in which the proportion of 5F71μ carbon black (GPF) was varied. The results are shown in Table 3.

(Margins below) From the results shown in Tables 1 to 3, it is clear that 55 to 95 parts by weight of soft carbon, 5 to 30 parts by weight of phenolic thermosetting resin, and all of the hardening agent are combined with 100 parts by weight of rubber, and soft carbon By setting the additional blending amount of the and phenolic thermosetting resin in the range of 60 to 100 parts by weight, the objective of the present invention is to achieve hardness JIS Hs of 92 or higher, Mooney viscosity of 60 or lower, and green strength of 10 kg/cIn2 or lower. It was confirmed that a rubber composition could be obtained.

Examples 12 to 14 The same procedure as in Example 1 was carried out using each rubber composition shown in Table 4 in which the average particle diameter of carbon black was changed, and as a result, as shown in Table 4, the average particle size was Diameter is 40m
When soft carbon having a particle diameter of μ or more was used, an excellent rubber composition, which is the object of the present invention, was obtained.

(Leaving space below) Table 4 Examples 15 to 18 When the same procedure as in Example 1 was carried out for each rubber composition in which the type of phenolic thermosetting resin shown in Table 5 was changed, the results shown in Table 5 were obtained. Excellent results were obtained in both cases.

Table 5 Example 19 A rubber composition having a hardness JIS )is of 92 in the present invention was mixed with the bead filler 4 and the bead portion reinforcing rubber 6 shown in FIG.
Tires with a structure as shown in Figure 3 (155S
R13 size) was molded and tested for durability, handling stability, and ride comfort using actual vehicles.

The results are shown in Table 6.

For comparison, Table 6 shows the hardness of rubber compositions according to JIS
Those with Hs of 80 were used for the bead filler 4 in Figure 1 (Comparative Example 11), those used for the bead filler 4 in Figure 2 (Comparative Example 12), and the bead filler 4 and beads in Figure 3. The material used for the reinforcing rubber 6 (Comparative Example 13) is also shown. All tires used were 155 SR13 size.

(Margins below) Table 6 Note: Values within 1.0 are index 24 when the value of Comparative Example 11 is taken as 100.Durability...Distance traveled until bead breakage (Km) Traveling conditions : Internal pressure 1.4kg/cIrL2 speed 81Km
/hr Sin of load 330 ± 100 Yu pumping dynamic load 3, steering stability... Lateral rigidity force of tire (kg)
Conditions: Internal pressure 1.9kg/crIL2 load City 37
0kg Lateral displacement 20% 4 Ride comfort... Tire protrusion impact force (kg) Conditions: Internal pressure 1.9 klil/cIrL" load
370klil Speed 60Km/hr Protrusion 10R As can be seen from Table 6, the tire of Comparative Example 11 had extremely poor ride comfort (the greater the impact force of the protrusion, the worse the ride comfort), and the tire of Comparative Example 12゜13 Comparative example 1 showed that although the tire provided better riding comfort, the steering stability was significantly worse.
Tire No. 2 also has inferior durability. On the other hand, the tire of the present invention has excellent not only durability but also very good handling stability, maintains ride comfort at a level that does not pose much of a problem, and is extremely excellent overall.

[Brief explanation of the drawing]

1, 2, and 3 each show a cross-sectional view of a bead portion of a tire. 1... Tip of folded part of carcass, 2... Sidewall part, 6... Carcass, 4... Bead filler,
5...Bead wire, 6...Pead part reinforcement comb. Agent Patent Attorney Shin Ogawa − Patent Attorney Ken Teru Noguchi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] This tire has a bead reinforcing rubber disposed between the folded part of the carcass and the sidewall, and the bead reinforcing rubber is arranged in a tongue-like manner to approximately the center of the sidewall, the tire including a bead filler and a bead reinforcing rubber. / Or the bead part reinforcing rubber is one or more of natural rubber, diene rubber, diene copolymer rubber, 55 to 95 parts by weight of soft carbon per 100 parts by weight of rubber, and 5 to 30 parts by weight. Part 7 of the ether-based thermosetting resin and curing agent were mixed so that the added amount of the soft carbon and the phenolic thermosetting resin was 60 to 100 parts by weight per 100 parts by weight of the rubber content. A tire comprising a compounded rubber composition.