JP3106258B2 - Pneumatic radial tire - Google Patents

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 an aromatic polyamide fiber cord (hereinafter, referred to as an aramid fiber cord), in which the adhesion between the aramid fiber cord and the coated rubber in the belt layer is improved. Related to pneumatic radial tires.

[0002]

2. Description of the Related Art In recent years, the global warming phenomenon has become a problem,
There is a growing movement to regulate the amount of carbon dioxide released into the air. Therefore, saving the consumption of fossil fuels has become an issue, and there is a strong demand for vehicles that have improved fuel efficiency by reducing weight. By the way, in order to reduce the weight of the pneumatic radial tire, it is desired to use an aramid fiber cord having a lower specific gravity than a steel cord for its belt layer, but the aramid fiber cord has poor adhesion to a rubber material (coated rubber), For this reason, water resistance and heat resistance between the aramid fiber cord and the coated rubber are particularly problematic.

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

[0004]

SUMMARY OF THE INVENTION The present invention relates to a tire having a belt layer in which an aramid fiber cord is embedded in a coated rubber, the adhesive strength between the aramid fiber cord and the coated rubber in the belt layer, particularly, water resistance and heat resistant bonding. An object of the present invention is to provide a pneumatic radial tire with 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 coated rubber, wherein the coated rubber has a weight average molecular weight. Is characterized by using a rubber composition containing a diene oligomer in the range of 20,000 to 100,000, a resorcinol precondensate, and hexamethoxymethylmelamine.

As described above, in the present invention, since the rubber composition containing a diene oligomer, a resorcinol precondensate, and hexamethoxymethylmelamine is used as a coating rubber, the adhesive force between the aramid fiber cord and the coating rubber in the belt layer is reduced. It can be improved. 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 the pneumatic radial tire of the present invention. In FIG. 1, an outer belt layer 2 in contact with a tread 1 is made of an aramid fiber cord, and an inner belt layer 3 is made of a steel cord.
4 is a carcass layer and 5 is an inner liner layer. FIGS. 2, 3 and 4 are schematic cross-sectional views each showing a laminated structure of a belt layer made of aramid fiber cord and a belt layer made of steel cord in the present invention. Aramid fiber cord is used for the belt layer 2, and steel cord is used for the inner belt layer 3.

In the present invention, a rubber composition containing a diene monomer, a resorcinol precondensate, and hexamethoxymethyl melamine is used as a coating rubber for the belt layer made of aramid fiber cord, that is, the outer belt layer 2. This rubber composition may be used as a coating rubber for the inner belt layer 3 made of a steel cord. Examples of the rubber component of the rubber composition include rubbers useful for belt layers, for example, natural rubber, butyl rubber, acrylonitrile / butadiene copolymer rubber (NBR), styrene / butadiene copolymer rubber (SBR), polybutadiene rubber (B
R) and mixtures thereof, but are 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 properties (particularly, tensile strength) of the compound (rubber composition) are greatly reduced. If it exceeds 100,000, it can no longer be called an oligomer and cannot be distinguished from a polymer.
The high degree of migration is lost.

The compounding amount of the diene oligomer is 0.5
~ 10 parts by weight. Less than 0.5 parts by weight has no compounding effect, while more than 10 parts by weight has physical properties as a compound.
(Especially the tensile strength) is greatly reduced. The amount of the resorcinol precondensate is preferably in the range of 0.5 to 3 parts by weight. If the amount is less than 0.5 part by weight, the effect of improving the strength properties 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) 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. However, if it exceeds 5 parts by weight, the physical properties deteriorate, which is not preferable. further,
The organic acid cobalt is converted to an elemental cobalt amount of 0.05 to 0.5.
You may mix | blend within the range of a weight part. Specific examples of the organic acid cobalt acid include cobalt naphthenate, cobalt octylate, and boron-organic acid cobalt complex (for example, “Manobond” 680C manufactured by Manchem).

Further, the rubber composition of the present invention is appropriately compounded with a compounding example, such as carbon black, a vulcanization accelerator, sulfur, an antioxidant, etc., which is compounded in a normal rubber composition. HAF is preferred as carbon black.

[0013]

EXAMPLES Each of the rubber compositions A, B and C having the compounding contents (parts by weight) shown in Table 1 was used, and each of them was 1500 D / 2 "Kevlar".
Cover the cord with bias ply, and at 160 ° C
Vulcanize for 15 minutes to make a test sample, peel strength after immersion in water (normal temperature) for 1 day and 3 days (water-resistant adhesion)
Was measured. The peel strength (heat resistance) was measured at 100 ° C. Table 2 shows the results.

[0014] In the above table, 3C is Nocrack 3C (N-phenyl-N'-
(1,3-dimethylbutyl) -p-phenylenediamine)
HMMM is hexamethoxymethylmelamine and 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 values in parentheses indicate the rubber coverage. The case where the peeled surface was completely covered with rubber was set to 5.0, and the case where the aramid fiber cord appeared on the entire surface was set to 1.0. As is clear from Table 2, when the isoprene oligomer, the resorcinol precondensate, and hexamethoxymethylmelamine (HMMM) are combined, the heat resistance and the water resistance are improved. The reason for such an effect is considered as follows.

First, the isoprene oligomer is considered to be higher in reactivity with the resorcinol precondensate and HMMM than natural rubber because of its small molecular weight. Also,
Low molecular weight makes it easy to move through rubber,
It can be said that migration to the aramid fiber cord interface is large.
On the other hand, resorcinol precondensate and HMMM are also
Easily migrates to the mid fiber cord interface. Therefore, Oite isoprene oligomer and resorcinol initial combination to perform the aramid fiber cords / rubber interface the like in the present invention
The condensate reacts with HMMM, and the resulting reaction product
The compound enhances the adhesion of rubber to aramid fiber cord.
Dip layer (latex (low molecular weight di
Ene-based polymer) and resorcin-formalin condensate
Become an adhesive layer. In addition, epoxy resin and isocyanate
Compounds may be compounded. ) And during tire vulcanization
Will cause co-crosslinking. Alami
It is thought that the adhesive strength between the fiber cord and rubber is improved.
It is. Thus, the reaction with the aramid fiber cord is performed.
Is limited to diene-based oligomers.

[0017]

As described above, according to the present invention, a diene oligomer having a weight average molecular weight in the range of 30,000 to 100,000, a resorcinol precondensate, and a hexamer as a coating rubber for a belt layer comprising an aramid fiber cord. To use a rubber composition containing methoxymethylmelamine,
It is possible to improve the adhesive strength between the aramid fiber cord and the coat rubber in the belt layer.

[Brief description of the 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 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 one 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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 61:28)

Claims (1)

(57) [Claims] 1. A tire having at least one belt layer in which an aromatic polyamide fiber cord is embedded in a coat rubber, wherein the coat rubber has a diene oligomer having a weight average molecular weight in the range of 20,000 to 100,000, A pneumatic radial tire using a rubber composition containing a resorcinol precondensate and hexamethoxymethylmelamine.