KR20030068602A - A process of preparing for rubber reinforcing polyester tire cord - Google Patents

Abstract

PURPOSE: A manufacturing method of polyester tire cord for reinforcing rubber is capable of solving environmental pollution, loss of workability, a gel forming problem and rise of a cost, increasing rubber adhesive property of the tire cord, deteriorating stiffness and preventing tip rise development. CONSTITUTION: The polyester tire cord for reinforcing rubber is obtained by the steps of: (i)dipping 100pts.wt. of polyester cord under at least 0.5g/d of tensile strength in a first dipping composition solution containing 0.3-0.8pts.wt. of sorbitol type epoxy resin, 0.5-1.0pts.wt. of blocked isocyanate and 1.5-3.0pts.wt. of vinyl pyridine latex, followed by drying and stretching the dipped polyester cord; and then (ii)dipping the polyester cord in a second dipping composition solution containing 1.5-3.0pts.wt. of isocyanate based on 100pts.wt. of a mixture of resorcinol, formalin and rubber latex, followed by drying and normalizing the polyester cord at 235-240deg.C.

Description

Process for preparing polyester tire cord for rubber reinforcement {A process of preparing for rubber reinforcing polyester tire cord}

The present invention relates to a method for producing a polyester tire cord for reinforcing rubber.

More specifically, the present invention relates to a method of manufacturing a rubber reinforcing polyester tire cord having excellent softness and good softness due to excellent adhesion to rubber and low stiffness.

Polyester fiber represented by polyethylene terephthalate fiber used as a reinforcing material in the production of polyester tires has poor adhesiveness with rubber, and is mainly composed of parachlorophenol-based resorcinol / formalin mixed resin (PEXUL) and epoxy and isocyanate compounds. The method of improving the adhesiveness of the polyester fiber to the rubber by coating the adhesive on the fiber surface has been studied for a long time.

First, the conventional method using a parachlorophenol-based resorcinol / formalin mixed resin (PEXUL) is a polyester cord is water, resorcinol, formalin, rubber latex and parachlorophenol-based resorcinol / formalin mixed resin (PEXUL) A method of first impregnation with a primary dipping composition consisting of a) followed by a second impregnation treatment with a second dipping composition consisting of a mixture of resorcinol, formalin and rubber latex (hereinafter referred to as "RFL") is known. .

However, in the above method, the parachlorophenol-based resorcinol / formalin mixed resin (PEXUL) of the primary dipping composition contains 70% by weight or more of ammonia water used as the main solvent. Ammonia is designated as an air pollutant due to the generation of harmful gases, which requires a purification facility to deal with it, and it may cause problems of workability and workplace pollution due to unique smell in the field work.

After impregnation with the primary dipping composition, small gels, which are types of impregnated dust, are generated by resorcinol, formalin, etc. in the composition solution, resulting in a high defective rate during tire production and a high unit weight of the impregnated polyester fiber. There is a disadvantage in that the cost burden increases.

In order to improve the above problems, the polyester fiber is impregnated with a primary dipping composition consisting of a mixture of diisocyanate and epoxy compound blocked with caprolactam or phenol, followed by primary dipping poly There has also been proposed a method of secondary dipping of ester fibers in a secondary dipping composition consisting of an initial condensate of resorcinol and formaldehyde and a mixture of rubber latex (RFL).

However, in the case of the above method, environmental pollution and gel generation can be remarkably improved, but due to the use of a hardenable epoxy and isocyanate, the stiffness of the polyester fiber is significantly high after heat treatment, so that the tip rises during tire manufacturing. (Tip Rise) phenomenon (also called a curl up phenomenon) occurs, there is a problem that the tire defective rate is increased.

If excessive softener is used in the heat treatment process to reduce the rigidity of the fiber, curled up occurs in the treated polyester fiber itself. It is necessary to reduce the rigidity of the polyester fiber itself.

In addition, in the case of lowering the content of epoxy and isocyanate in the primary dipping composition in order to reduce the stiffness of the polyester cord, there is a problem in that the adhesion performance with the rubber worsens.

An object of the present invention is to produce a soft polyester tire cord having a low stiffness and excellent adhesion with rubber to solve the problems of the prior art.

The present invention is to provide a method for producing a polyester tire cord that can prevent the tip rise (Tip Rise) phenomenon at the time of manufacturing tires with excellent adhesion to rubber and low rigidity. In addition, the present invention is an environmental pollution problem when using a primary dipping composition containing a parachlorophenol-based resorcinol / formalin mixed resin (PEXUL), workability problem, tire failure problem due to gel (gel) and manufacturing cost problems To provide a way to solve them.

Method for producing a polyester tire cord of the present invention for achieving such problems is (i) 0.3 to 0.8 parts by weight of sorbitol type epoxy resin, 0.5 to 1.0 weight of broken isocyanate based on 100 parts by weight of pure polyester cord Secondary dipping composition containing 1.5 parts to 3.0 parts by weight of vinylpyridinate and impregnated under a tension of 0.5 g / d or more, followed by drying and stretching; and (ii) a resorcinol, formalin and rubber latex mixture (RFL). It is characterized by impregnating the secondary dipping composition containing 1.5 to 3.0 parts by weight of isocyanate based on 100 parts by weight and drying and normalizing it.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

First, the polyester cord is impregnated in a primary dipping composition mixed with pure water, sorbitol type epoxy resin, broken isocyanate and vinylpyridin latex under a tension of 0.5 g / d or more, and then dried and stretched. As the first dipping composition, 0.3 to 0.8 parts by weight of sorbitol-type epoxy resin, 0.5 to 1.0 parts by weight of broken isocyanate and 1.5 to 3.0 parts by weight of vinylpyridin latex are used with respect to 100 parts by weight of pure water.

At this time, when the content of the sorbitol type epoxy resin and the broken isocyanate exceeds the above range, the stiffness of the final polyester tire cord is rapidly increased, so that the tip rise phenomenon is severe when the tire cord is manufactured. Is generated. On the other hand, when the content of the sorbitol type epoxy resin and the broken isocyanate is lower than the above range, the adhesion with rubber is lowered.

Vinylpyridine latex is added to increase the viscosity of the primary dipping composition, it is preferred that the vinylpyridine monomer, styrene and butadiene in a weight ratio of 15:15:70.

When impregnating the polyester cord paper with the primary dipping composition, the tension is maintained at 0.5 g or more per denier of yarn constituting the polyester cord paper. For example, when polyester cord paper is woven from yarns in which two 1500 denier polyester fibers are twisted, the tension should be maintained at 1.5 kg or more during the primary dipping process.

If the tension is less than the above range, a large amount of epoxy and isocyanate in the primary dipping composition penetrate into the cord paper, thereby increasing the rigidity of the product too much.

After the first dipping treatment as described above, the drying is carried out at 145 ~ 155 ℃ for 2 minutes, the stretching is preferably carried out at a temperature of 240 ~ 245 ℃.

Next, the primary dipping polyester cord as described above was impregnated into a secondary dipping composition containing 1.5 to 3.0 parts by weight of isocyanate based on 100 parts by weight of a conventional resorcinol, formalin and rubber latex mixture (RFL). It is then dried and normalized (Normalizing) to prepare a polyester reinforcing polyester tire cord of the present invention.

At this time, when the isocyanate content exceeds 3.0 parts by weight, the cost and stiffness (stiffness) is increased, and when less than 1.5 parts by weight, the adhesive strength with the rubber is lowered. The normalizing treatment after the second dipping treatment is preferably carried out at a temperature of 235 ~ 245 ℃.

Polyester tire cord produced by the present invention is excellent in softness and low rigidity at the same time excellent in adhesion with rubber. As a result, tip rise is prevented during tire manufacturing.

In the present invention, the rubber adhesive strength and stiffness of the polyester tire cord was evaluated by the following method.

Rubber Adhesion (kgf)

The polyester tire cord and rubber having a thickness of 3/8 inch were measured after vulcanization at 160 ° C. for 20 minutes at a vulcanization pressure of 20 kgf / cm 2.

Stiffness (g / d)

It was measured by ASTM D 885 M method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following examples.

Example 1

The polyester cord of 1500 denier / 2 combinations is impregnated with a secondary dipping composition composed of 100 parts by weight of pure water, 0.6 parts by weight of sorbitol type epoxy resin, 0.9 parts by weight of broken isocyanate and 1.7 parts by weight of vinylpyridine latex. At this time, the speed was 40m / min, the tension was adjusted to 1.8kg / cord. The vinyl pyridine latex was used as the content ratio of vinyl pyridine monomer, styrene, butadiene 15:15:70. Subsequently, the primary dipping (impregnated) polyester cord is dried at 150 ° C. for 2 minutes and then stretched to 243 ° C. Subsequently, the polyester cord treated as described above was impregnated with a secondary dipping composition containing 2.5 parts by weight of isocyanate based on 100 parts by weight of RFL, dried at 150 ° C. for 2 minutes, and then normalized to 240 ° C. to give rubber A reinforcing polyester tire cord is produced. The results of measuring physical properties of the manufactured tire cords are shown in Table 2.

Example 2 and Comparative Example 1 to Comparative Example 3

A polyester tire cord for rubber reinforcement was manufactured under the same process and conditions as in Example 1, except that the production conditions such as the composition of the primary and secondary dipping compositions and the tension during the primary dipping treatment were changed as shown in Table 1. do. The results of measuring physical properties of the manufactured tire cords are shown in Table 2.

Manufacture conditions division Example Comparative Example One 2 One 2 3 Primary Dipping Composition (parts by weight) pure 100 100 100 100 100 Sorbitol type epoxy resin 0.6 0.5 One 0.6 0.6 Broken Isocyanates 0.9 0.7 3 0.9 0.9 Vinyl pyridine latex 1.7 2 2 2 1.7 2nd dipping composition (weight part) RFL 100 100 100 100 100 Isocyanate 2.5 2 2 0 2.5 Primary dipping tension (kgf / cord) 1.8 2 2 2 0.6 Drying temperature (℃) 150 150 150 150 150 Stretching temperature (℃) 243 240 243 243 243 Normalizing Temperature (℃) 240 240 240 240 240

Tire cord properties division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Adhesive force (kgf) 16.2 15.3 16.5 11.5 16.3 Stiffness (g / cord) 6.4 5.6 15.5 5.5 11.5

The present invention can effectively prevent the environmental pollution problem, workability problem, gel formation problem, manufacturing cost increase problem, etc. which are commonly caused when using a primary dipping composition containing a parachlorophenol-based resorcinol / formalin mixed resin (PEXUL) Can be. In addition, the present invention can improve the rubber adhesiveness of the polyester tire cord and at the same time reduce the rigidity can prevent the tip rise (Tip Rise) phenomenon in the tire manufacturing.

Claims (3)

(Iii) A polyester dipping composition containing 0.3 to 0.8 parts by weight of sorbitol-type epoxy resin, 0.5 to 1.0 parts by weight of broken isocyanate and 1.5 to 3.0 parts by weight of vinylpyridin latex per 100 parts by weight of pure water. Impregnated under a tension of 0.5 g / d or more, followed by drying and stretching; and (ii) to a secondary dipping composition containing 1.5 to 3.0 parts by weight of isocyanate based on 100 parts by weight of a resorcinol, formalin and rubber latex mixture (RFL). Method of producing a polyester reinforcing polyester tire cord characterized in that it is impregnated and then dried and normalized. The method for producing a polyester tire cord for rubber reinforcement according to claim 1, wherein the stretching treatment temperature is 240 to 245 ° C. The method for producing a rubber reinforcing polyester tire cord according to claim 1, wherein the normalizing treatment temperature is 235 to 240 ° C.