JPS6366381A - Rubber reinforcing fiber cord - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a fiber cord suitable for reinforcing rubber products such as pneumatic tires, belts, and hoses, and more particularly to a fiber cord with significantly improved durability. This invention relates to a fiber cord for reinforcing pneumatic tires.

(Prior art) Generally, in rubber products reinforced with fiber cords, a mixture of resorcinol formaldehyde first 3UI condensation proboscis and rubber latex (hereinafter referred to as RFL adhesive) is used to bond the fiber cords and rubber. (Japanese Patent Application Laid-Open No. 60-72929,
(See Publications No. 60-72930, No. 60-72972, and No. 60-250036).

Furthermore, various techniques have been proposed to improve hook adhesion. For example, JP-A-60-99073
In the publication, aramid fibers are mixed with polyepoxide compound (8) and bismaleimide derivative (B) with B/A ratio of 1/2.
It is disclosed that the second treatment agent is used at a mixing ratio of ~1/l. Further, Japanese Patent Application Laid-open No. 60-146082 discloses coating aromatic polyamide fiber filaments with a reaction product of an epoxy resin and an incompletely cured thermosetting aldehyde resin. Further, JP-A-60-146084 discloses pre-treating polyester fibers with a treatment agent containing an epoxy compound.

Although the adhesion improvement techniques described above relate to organic fibers, techniques for improving the adhesion between inorganic fibers and rubber have also been proposed. For example, JP-A-60-18136
No. 9 discloses a carbon Ifi fiber bundle poxy compound (
E) and rubber latex (L) at solid bone mass ratio E/L・
After applying 10 to 80% by weight of the 1/9 to 9/1 blend, heat treatment was performed, and then 0.5 to 10% of the RFL adhesive was applied.
A corrugated carbon fiber cord for rubber reinforcement is characterized in that it is heat-treated after being applied with a weight percent.

(Problems to be Solved by the Invention) As is clear from the above-mentioned prior art, polyamide fibers (including aromatic polyamide fibers), polyester fibers (flag polyester fibers), and Epoxy treatment has been widely used for bonding organic fibers such as polyvinyl alcohol fibers such as polyvinyl alcohol fibers (including polyvinyl alcohol fibers), and inorganic fibers such as carbon fibers and glass fibers. However, when treated with epoxy,
Due to the hard epoxy layer, the fatigue resistance of the fiber cord is reduced and the adhesiveness is also unstable.

Accordingly, an object of the present invention is to provide a rubber reinforcing fiber cord that has excellent stress resistance and adhesive properties by performing a treatment other than epoxy treatment.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the inventors of the present invention have found that adhesive properties can be improved by treating fiber cords with a water-soluble polyamide solution before adhesive treatment. The inventors have also discovered that a rubber reinforcing fiber cord with excellent fatigue resistance can be obtained, and have arrived at the present invention.

That is, the present invention provides a rubber reinforcing material whose durability is significantly improved by dipping raw fiber filaments, bundles, or twisted cords in a water-soluble polyamide solution, heat-treating them, and then subjecting them to adhesive immersion treatment and heat treatment. It concerns textile cords.

In the present invention, aramid fibers, polyamide fibers such as nylon 6, nylon 6.6, nylon 4,6, etc., polyester fibers such as fully aromatic polyester, polyethylene terephthalate, etc., polyvinyl alcohol fibers such as high tensile vinylon, etc. Either organic fibers or inorganic fibers such as carbon fibers and glass fibers can be used.9 The water-soluble polyamide in the present invention has the following general formula, for example: halogen atom, n is an integer from 1 to 6), but for fiber use, the substituent in the above formula is 10C0N
I+, is preferred.

Further, the solution of the water-soluble polyamide may be not only an aqueous solution but also an alcohol solution, but an aqueous solution is preferable from the viewpoint of fire prevention and health and safety.

The fibers can be immersed in the water-soluble polyamide solution by immersing the raw yarn or twisted cord for a relatively short period of time, or by soaking the twisted cord for a long time to completely coat each filament with the water-soluble polyamide. It may be covered.

For the heat treatment after immersion in the water-soluble polyamide solution, the optimal conditions should be selected depending on the type of fiber.
It is preferable to perform the heat treatment at 60 to 240°C for a heat treatment time of 2 to 10 minutes. Stretching may or may not be performed at the same time as this heat treatment.

Next, the adhesive in the present invention may be an RFL adhesive (here, the rubber latex is, for example, a rubber-like vinyl pyridine copolymer latex) which is usually used for reinforcing rubber, or the adhesive disclosed in the following publications. Adhesives may also be used.

1) JP-A No. 60-146084 Niresorcin, formalin 1 A mixture consisting of acrylonitrile-butadiene-rubber latex and a phenolic compound represented by the following general formula 2) JP-A No. 60-72972 Common axis: (al general formula (However, X is a positive integer of 1 to 8, y is an integer of 2 or 3,
(n represents O or a positive integer from 1 to 15) A component (A) in which the number of polyhydric phenols linked by S is 4 or more and 30% or less is a polyhydric phenol polysulfide represented by (n represents O or a positive integer from 1 to 15) bl A resorcinol-formaldehyde condensate with an excess of resorcinol synthesized without a catalyst or under a weakly acidic catalyst, with a reaction molar ratio of resorcinol and formaldehyde in the range of 1.0:0.1 to 1.0:0.75. The number of connected resorcins is 5
Component (B) in which 35% or less of 35% or more, (C) a resol type synthesized in the presence of an alkali catalyst at a reaction molar ratio of resorcin and formaldehyde in the range of 1:1.0 to 1.0, 0. The resorcinol formaldehyde condensate and rubber latex are mixed in a solid weight ratio of 1:
100-35: R mixed in the range of 100
FL liquid (C), [d) The above components in solid weight ratio (A): (B) = to: 100-50
: 100 and the monomer content when mixing (A) + (B) is 20% or less, ((A) + (B) ) : (C)・1 : 0.5 ~
An adhesive for fiber materials made by mixing in a ratio of 1:2.

3) JP-A-60-250036: Polymer resorcinol-formaldehyde initial condensate and rubber latex,
Further, a low molecular weight resorcinol-formaldehyde initial condensate and a polyhydric phenol polysulfide represented by the following general formula (wherein X is 1 to 6, y is 2 to 3, and n is an integer of 1 to 15) are mixed. Adhesive made by

4) JP-A-60-72930: (a) The reaction molar ratio of resorcinol and formaldehyde is 1.0:0.1 to 1.0? 0.75, and is a resorcin-rich formaldehyde condensate synthesized without a catalyst or under a weak acidic catalyst, and the number of resorcins linked by formaldehyde is 5.
After coating the fiber material with component (A) in which the content of resorcinol monomers is 35% or less and the resorcinol monomer content is 20% or less, heat treatment is performed, and (b) resorcinol and formaldehyde are combined in the presence of an alkali catalyst. Reaction molar ratio 1.0
: 1.0 to 1.0 : 7.0 A resol type resorcin formaldehyde condensate synthesized in the range of 7.0 and rubber latex at a solid content weight ratio of 1:100 to 35 :
A two-step adhesive made by applying a mixed RFL liquid (B) and then heat-treating it so that it has a molecular weight of 100%.

(Function) As explained above, the fibers that have been impregnated with water-soluble polyamide and heat treated can be used as is if they are twisted cords, or if they are raw yarns, they can be made into twisted cords and then treated with the adhesive and heated. After processing, it is embedded in unvulcanized rubber, molded and vulcanized, and then acts as a reinforcing agent for rubber products.

In the rubber reinforcing fiber cord of the present invention, the fiber surface is coated with a soft polyamide resin, which acts to alleviate bending and compression strains, thereby greatly improving the durability of the cord.

This polyamide resin adheres well to the fiber surface, and at the same time has good affinity with the adhesive, resulting in good adhesion between the fiber cord and the covering rubber.

Aramid fiber (manufactured by Kijin Co., Ltd., trade name: Technolar) expressed by the following general formula, in an aqueous solution with a concentration of 10% by weight of a water-soluble polyamide resin expressed by the following general formula: After dipping the twisted cord consisting of 230
Heat treatment was performed at ℃ for 6 minutes. Next, the treated cord was immersed in an RFL adhesive having the composition shown in Table 1 below, and then heat-treated at 240° C. for 1 minute.

Table 2 The twisted cord treated above is stretched to a length of 200 am and placed in a mold with a depth of 2 mm, and the unvulcanized rubber described in Table 2 below is lined with reinforcing cloth. The compound is bonded and vulcanized by heating and pressurizing at a temperature of 160°C for 20 minutes,
The cord was peeled from the vulcanized rubber at a tensile speed of 300 am/min, and the peel adhesion between the rubber and the cord was measured.

Furthermore, fatigue tests were conducted based on strength measurements and belt bending test methods. First, length 50cI11, width 5cm
, apply the above processing code 5 in the length direction of the mold with a depth of IC11.
0 pieces in parallel, joined with the unvulcanized rubber composition listed in Table 2, heated and pressurized at a temperature of 145°C for 40 minutes,
Vulcanization was performed. The test piece obtained by this method was tested using a belt bending tester with a pulley diameter of 80φ and a load of 125.
Bending fatigue was applied repeatedly 200,000 times under the condition of 200,000 kg.

The strength of the cord taken out from this test piece was measured using a fiber cord tensile testing device at a tensile speed of 300 mm/min, and compared with the initial strength before fatigue.

The test results obtained are shown in Table 4 below.

Table 1 The same procedure as in Example 1 was carried out except that one cord of the same aramid fiber was immersed in an aqueous solution of the same water-soluble polyamide resin as in Example 1 for 6 hours to ensure sufficient impregnation. Fatigue properties were evaluated. The test results obtained are shown in Table 4 below.

This 4-inch construction 1 After immersing the same aramid fiber twisted cord as in Example 1 in the epoxy aqueous solution shown in Table 3 below for 2 seconds, the cord was heated to 250°C.
After heat treatment for 2 minutes, the same operations as in the examples were performed to evaluate peel adhesion and fatigue properties. The test results obtained are shown in Table 4 below.

The strength retention rate after bending fatigue in Table 4 indicates the fatigue resistance of the fiber cord in the belt-shaped test piece, and from this test result, the fiber coated with a polyamide resin with a soft surface has a high resistance to bending. It can be seen that the fatigue resistance of the cord is improved because the compression strain is alleviated. In addition, polyamide resin has good reactivity with RFL adhesives, which can also be seen from the fact that the peel adhesive strength of Examples 1 and 2 in Table 4 is higher than that of Comparative Example 1. It can be confirmed.

(Effects of the Invention) As explained above, in the rubber reinforcing fiber cord of the present invention, both adhesiveness and fatigue resistance are improved by treating the fiber cord with a water-soluble polyamide solution before adhesive treatment. The effect is that it can be improved. still,
Achieving both adhesion and fatigue resistance is extremely important for the practical use of belts and tires.
It can be said that this method satisfies two requirements at the same time, and has an extremely excellent effect.

Claims (1)

[Claims] 1. A rubber reinforcing fiber cord whose durability is significantly improved by dipping a fiber filament, a yarn bundle, or a twisted cord in a water-soluble polyamide solution, heat-treating it, and then subjecting it to adhesive immersion treatment and heat treatment.