JPH08142605A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To improve the adhesion between a cord and a coat rubber in a belt layer by using the rubber composition containing diene oligomer whose weight average molecular weight is in the prescribed range, the resorcinol initial condensate, and the hexamethoxymethylmelamine as the coat rubber. CONSTITUTION: The rubber composition containing the diene monomer, the resorcinol initial condensate, and the hexamethoxymethylmelamine as the coat rubber of the belt layer consisting of the aramid fiber cord, i.e., the outer side belt layer 2 is used. This rubber composition may be used as the coat rubber of an outer side belt layer 3 consisting of the steel cord. Diene-oligomer is e.g. isoprene oligomer, butadiene oligomer, styrene butadiene copolymer oligomer, or the like, and the weight average molecular weight is in the range of 20,000 to 100,000. The adhesion between the Aramid fiber cord in the belt layer and the coat rubber, especially the waterproof and heat resistant adhesion can be improved thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire having a belt layer made of aromatic polyamide fiber cord (hereinafter referred to as aramid fiber cord), which improves the adhesive force between the aramid fiber cord and the coat rubber in the belt layer. For pneumatic radial tires.

[0002]

2. Description of the Related Art In recent years, the global warming phenomenon has become a problem,
There has been increasing movement to regulate the amount of carbon dioxide released into the air. Therefore, saving fossil fuel consumption is an issue, and there is a strong demand for vehicles that are lighter in weight and have improved fuel efficiency. By the way, in order to reduce the weight of pneumatic radial tires, it is desirable to use aramid fiber cords, which have a lower specific gravity than steel cords, in the belt layer, but aramid fiber cords do not adhere well to rubber materials (coat rubber), For this reason, water resistance and heat resistant adhesion between the aramid fiber cord and the coated rubber are particularly problematic.

Under such circumstances, the tire structure is intended to cover the drawbacks of the aramid fiber cord.
JP-A-2-128903, JP-A-2-38103, JP-A
There is a 1-204802 publication. Further, Japanese Patent Laid-Open No. 1-240305 attempts to solve the problem by devising the modulus of the coat rubber (coat compound) for coating the aramid fiber cord. JP-A 1-239134, JP-A 63
-196778, JP 63-66382, JP 63-663
No. 81 discloses a similar approach in treating aramid fiber cord. As an approach from the coating compound, there is JP-A-1-168505, however, the water resistance between the aramid fiber cord and the coating rubber,
It cannot be said that heat-resistant adhesion has been completely solved.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a tire having a belt layer in which aramid fiber cords are embedded in coated rubber, wherein the adhesive force between the aramid fiber cords and the coated rubber in the belt layer, particularly water resistance and heat resistant adhesion. An object of the present invention is to provide a pneumatic radial tire having improved power.

[0005]

The pneumatic radial tire of the present invention is a tire having at least one belt layer in which an aromatic polyamide fiber cord is embedded in a coat rubber, and the weight average molecular weight of the coat rubber is Is used in the range of 20,000 to 100,000, and a rubber composition containing a diene-based oligomer, a resorcin precondensate, and hexamethoxymethylmelamine is used.

As described above, in the present invention, since the rubber composition containing the diene oligomer, the resorcin initial condensate, and hexamethoxymethylmelamine is used as the coat rubber, the adhesive force between the aramid fiber cord and the coat rubber in the belt layer is improved. It is possible to improve. Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective half sectional view showing an example of a pneumatic radial tire of the present invention. In FIG. 1, the outer belt layer 2 in contact with the tread 1 is made of an aramid fiber cord, and the inner belt layer 3 is made of a steel cord.
4 is a carcass layer and 5 is an inner liner layer. Further, FIGS. 2, 3 and 4 are schematic cross-sectional views each showing an embodiment of a laminated structure of a belt layer made of an aramid fiber cord and a belt layer made of a steel cord according to the present invention. An aramid fiber cord is used for the belt layer 2, and a steel cord is used for the inner belt layer 3.

In the present invention, a rubber composition containing a diene monomer, a resorcin initial condensate, and hexamethoxymethylmelamine is used as a coat rubber for the belt layer made of an aramid fiber cord, that is, the outer belt layer 2. This rubber composition may be used as a coat rubber for the inner belt layer 3 made of steel cord. The rubber component of this rubber composition is a rubber useful for a belt layer, such as natural rubber, butyl rubber, acrylonitrile / butadiene copolymer rubber (NBR), styrene / butadiene copolymer rubber (SBR), polybutadiene rubber (B).
R) and mixtures thereof can be mentioned, but the invention is not limited thereto.

The diene-based oligomer is, for example, an isoprene oligomer, a butadiene oligomer, a styrene-butadiene copolymer oligomer, or the like. The weight average molecular weight is in the range of 20,000 to 100,000. If it is less than 20,000, the co-vulcanizability with rubber is poor, and the physical properties (particularly tensile strength) of the compound (rubber composition) are greatly reduced. When it exceeds 100,000, it can no longer be called an oligomer, and it cannot be distinguished from a polymer, and the reactivity as an oligomer,
High transitional property is lost.

The amount of this diene oligomer is 0.5
~ 10 parts by weight. If the amount is less than 0.5 part by weight, the compounding effect is not exerted, and if it exceeds 10 parts by weight, the physical properties as a compound are obtained.
(In particular, tensile strength) is greatly reduced. The compounding amount of the resorcin initial condensate is preferably in the range of 0.5 to 3 parts by weight. If the amount is less than 0.5 parts by weight, the effect of improving the strength characteristics of the rubber composition is not sufficient, and if it exceeds 3 parts by weight, the breaking strength of the rubber tends to decrease, which is not preferable.

The amount of hexamethoxymethylmelamine (hereinafter referred to as HMMM) compounded is in the range of 1 to 5 parts by weight. By blending this HMMM, the adhesiveness of the rubber composition, that is, the adhesiveness to the aramid fiber cord can be remarkably improved, but when it exceeds 5 parts by weight, the physical properties are deteriorated, which is not preferable. further,
Converting organic acid cobalt to the amount of elemental cobalt is 0.05 to 0.5
You may mix | blend within the range of a weight part. Specific examples of the organic acid cobalt include cobalt naphthenate, cobalt octylate, and boron-organic acid cobalt complex (for example, "Manobond" 680C manufactured by Manchem Co.).

Further, the rubber composition of the present invention is appropriately compounded with a compounding example to be compounded with a usual rubber composition, for example, carbon black, a vulcanization accelerator, sulfur, an antioxidant and the like. HAF is preferable as the carbon black.

[0013]

EXAMPLES Rubber compositions A, B, and C having the compounding contents (parts by weight) shown in Table 1 were used to obtain 1500 D / 2 "Kevlar", respectively.
Cover the cord with a ply biased at 160 ° C
Vulcanized for 15 minutes to prepare a test sample, and peel strength after immersion in water (normal temperature) for 1 day and 3 days (water resistance)
Was measured. The peel strength (heat resistance) was measured at 100 ° C. Table 2 shows the results.

[0014] In the above table, 3C is Nocrac 3C (N-phenyl-N'-
(1,3-dimethylbutyl) -p-phenylenediamine)
, HMMM is hexamethoxymethylmelamine, and the resorcin condensate is B-18 manufactured by Koppers. The weight average molecular weight of the isoprene oligomer is 50,000.

[0015] In Table 2 above, the rubber coverage is shown in parentheses, where the peeled surface was completely covered with rubber was 5.0, and the case where the aramid fiber cord appeared on the entire surface was 1.0. As is clear from Table 2, when the isoprene oligomer is combined with the resorcin initial condensate and hexamethoxymethylmelamine (HMMM), heat resistance and water resistance adhesion are improved. The reason for such an effect is considered as follows.

First, since the molecular weight of isoprene oligomer is small, it is considered that the reactivity with the resorcin initial condensate and HMMM is higher than that of natural rubber. Also,
The low molecular weight makes it easy to move through the rubber,
It can be said that the transferability to the aramid fiber cord interface is large.
Therefore, it is considered that when the combination as in the present invention is performed, a layer of the oligomer and the resin is formed at the aramid fiber cord / rubber interface, and thereby the adhesive force is improved. This is limited to diene-based oligomers. Further, if the co-vulcanizability is low and the molecular weight is less than 30,000, the same effect is not obtained.

[0017]

As described above, according to the present invention, a diene-based oligomer having a weight average molecular weight in the range of 30,000 to 100,000, a resorcin initial condensate, and hexa are used as a coat rubber for a belt layer made of an aramid fiber cord. In order to use a rubber composition containing methoxymethylmelamine,
It is possible to improve the adhesive force between the aramid fiber cord and the coat rubber in the belt layer.

[Brief description of drawings]

FIG. 1 is a perspective half-sectional view of an example of a pneumatic radial tire of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a belt layer laminated structure in the pneumatic radial tire of the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of a belt layer structure in the pneumatic radial tire of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of a belt layer laminated structure in the pneumatic radial tire of the present invention.

[Explanation of symbols]

 1 tread 2 outer belt layer 3 inner belt layer

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[Procedure amendment]

[Submission date] June 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026] It can be seen from Table 2 that all show good adhesiveness except for NBR having γc of 39 mN / m. Experimental Example 2 As shown in Table 3, the rubber composition Nos. 1 to 5 are used, and one of them is a vulcanized rubber material among rubber materials made of the same type of unvulcanized rubber composition,
50 % by weight of liquid paraffin on the surface of these rubber materials
The paste obtained by mixing the ultra-high molecular weight polyethylene powder of was applied and then laminated, and this was heated to be fused and integrated. The adhesion of the obtained rubber / rubber adhesive composite was evaluated, and the results are shown in Table 3.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

[0027] The raw rubber component is SBR (γc = 33 mN / m) 70: N
R (γc = 31 mN / m) 30 (weight ratio) of the rubber composition No. In the case of 3, when either one of the rubber materials is vulcanized, good adhesion cannot be obtained. On the other hand, when the raw material rubber component has a γc in the range of 25 to 32 mN / m, it is found that even if at least one rubber material is vulcanized, it has good adhesiveness. Experimental Example 3 As shown in Table 4, the rubber composition Nos. 2 (EPD
M) and No. 4 (IIR) and No. 4 2 (EPDM) and No. Regarding a combination of rubber compositions containing 1 (NR) of different raw material rubber components, both are unvulcanized, one is unvulcanized, the other is vulcanized and both are vulcanized. On the surface, a paste prepared by mixing liquid paraffin with 50 % by weight of ultra-high molecular weight polyethylene powder was applied and then laminated, and this was heated to be fused and integrated. The adhesion of the obtained rubber / rubber adhesive composite was evaluated, and the results are shown in Table 4.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028] As can be seen from Table 4, when a rubber composition containing different raw material rubber components was combined, depending on γc of the raw material rubber component and the vulcanization state (whether unvulcanized or vulcanized) of the rubber material,
The adhesiveness is different. Γc value of raw rubber component is 25 ~
EPDM within the range of 30 mN / m (γc = 28 mN
/ M) and IIR (γc = 27 mN / m) are combined, good adhesiveness is exhibited regardless of the vulcanized state. Experimental Example 4 As shown in Table 5, the rubber composition Nos. 2 (EPD
M) and No. 3 (SBR-NR), a rubber composition containing different raw rubber components, both unvulcanized, one unvulcanized, the other vulcanized and both vulcanized A paste prepared by mixing liquid paraffin with 50 % by weight of ultra-high molecular weight polyethylene powder was applied on the surface of the material and then laminated, and this was heated and fused and integrated. The adhesion of the obtained rubber / rubber adhesive composite was evaluated, and the results are shown in Table 5.

Claims (1)

[Claims] 1. A tire having at least one belt layer obtained by burying an aromatic polyamide fiber cord in a coated rubber, wherein the coated rubber has a weight average molecular weight of 20,000 to 100,000. A pneumatic radial tire using a rubber composition containing a resorcin precondensate and hexamethoxymethylmelamine.