JP2000355875A - Treatment of polyester fiber cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester fiber cord suitable for providing a rubber composite excellent in adhesion to a matrix rubber even if the composite is directly exposed to steam, and also good in durability. SOLUTION: The first treating liquid containing a dimer of a diisocyanate compound in the proportion of 0.4-1.5 wt.% expressed in terms of the attached amount of the dimer is imparted to a polyester fiber having an epoxy compound previously imparted thereto at a fiber-forming step, and in an untwisted state or a twisted cord state, and the resultant fiber is heat-treated at 180-240 deg.C for 60-180 sec. The heat-treated fiber is twisted when the fiber is in the untwisted state. The second treating liquid containing resorcin-formalin-rubber latex(RFL) is imparted to the resultant fiber, and the obtained fiber is heat- treated at 180-240 deg.C for 60-180 sec to provide the objective polyester fiber cord.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a polyester fiber cord which can be suitably used as a reinforcing cord for a power transmission belt or the like. More specifically, the present invention is suitable as a core wire cord of a wrapped V-belt, and has a good adhesiveness to a matrix rubber and a high durability even when exposed to leaked steam particularly when molded by steam vulcanization. The invention also relates to an excellent polyester fiber cord processing method.

[0002]

2. Description of the Related Art Polyester fiber cords generally have excellent properties such as strength, elastic modulus, dimensional stability, and heat resistance, so that rubber composites such as tires, belts, and hoses used under severe conditions are used. It is useful as an excellent reinforcing fiber, and is expected to expand its use.

Generally, reinforcing fibers for rubber composites such as belts are used in the form of twisted cords. Important properties for this cord include adhesion to matrix rubber, cord strength, balance between load elongation and dry heat shrinkage, heat shrinkage stress, and the like. For example, in the case of a belt, among these properties, the adhesive performance and the cord strength greatly contribute to the load resistance and durability of the finished belt, and the balance between the load elongation and the dry heat shrinkage ratio is dimensional stability during belt molding. It affects the performance (belt length). Further, the heat shrinkage stress affects the dimensional change during the running of the belt, and is closely related to the transmission efficiency of the belt. Therefore, there is a demand for a bonding technique and bonding processing conditions that balance these characteristics.

[0004] Regarding the adhesion between the polyester fiber cord and the rubber matrix, various kinds of resorcinol-formalin latex adhesives (RFL adhesives) have been conventionally proposed (for example, JP-A-57-187238, JP-A-57-238238). No. 60-110980, Japanese Patent Publication No. 8-2971, etc.). However, in general, when a belt is formed using a polyester fiber cord as a core wire, the belt is often formed by a steam vulcanization method, and steam is not directly sprayed on rubber / fiber material. They may be directly exposed to steam leaking from gaps. Therefore, in the fiber cord obtained by the method proposed above, several percent of the formed belt may have poor adhesion. That is, in the conventional bonding technology, the bonding performance of the power transmission belt that performs bending motion with a large number of pulleys, particularly as a reinforcing fiber cable cord, is insufficient, and it is a reality that sufficient durability is not obtained. Therefore, treatment with a solvent-based treating agent containing a compound having a free isocyanate group has been mainly performed for the purpose of improving the adhesive performance. However, such a solvent-based treatment is significantly inferior to a water-based treatment in terms of waste liquid treatment cost and work environment.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide excellent adhesiveness to a matrix rubber even when directly exposed to steam, and to have high durability. An object of the present invention is to provide a method for treating a polyester fiber cord which is suitable for obtaining a good rubber composite, particularly a power transmission belt.

[0006]

Means for Solving the Problems The object of the present invention is to provide:
"The first treatment liquid containing the dimer of the diisocyanate compound is applied in a non-twisted state or a twisted cord state to the polyester fiber to which the epoxy compound has been added in advance in the spinning stage, and the amount of the dimer is 0% based on the fiber weight in terms of the amount of the dimer attached. .4 to 1.5
At a temperature of 180 to 240 ° C.
After heat treatment for 0 to 180 seconds, twisting is applied to the non-twisted yarn, and then a second treatment liquid containing resorcinol / formalin / rubber latex (RFL) is applied.
And a heat treatment at 40 ° C. for 60 to 180 seconds.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester fiber in the present invention is preferably a fiber composed of a polyester whose repeating unit is substantially ethylene terephthalate, but other polyesters such as polyethylene terephthalate obtained by copolymerizing a small amount of a third component. Fibers consisting of In the present invention, a so-called epoxy pre-treated yarn in which epoxy is previously applied to the polyester fiber in a yarn-making step is used.

In the present invention, a first bonding process and a second bonding process, which will be described later, are performed while the pre-processed yarn remains untwisted or formed into a twisted cord. Here, the twisted cord is manufactured by a conventionally known method. For example, the yarns composed of the pre-processed yarns are arranged in a desired number, and the first twist is applied.
Although the number of twists is arbitrary, it is common to apply a smaller number of twists than the next twist. Next, the desired number of fibers that have been twisted are adjusted, and a twisting cord (raw cord) is formed by giving an upper twist in a direction opposite to the twisting.

In the present invention, first, a first bonding treatment is applied to the obtained raw cord or non-twisted polyester fiber yarn.

The first treatment liquid used in the first adhesion treatment must contain a dimer of a diisocyanate compound, for example, tolylene diisocyanate dimer, diphenylmethane diisocyanate dimer, metaxylylene diisocyanate dimer, or the like. The dimer of such a diisocyanate compound is usually a solid in the form of fine particles, and is used as an aqueous dispersion in which a dispersant such as dialkyl sulfosuccinate sodium salt is dissolved using a solution in water.

At this time, it is preferable to add a small amount of a thickener, in particular, xantham gum, for the purpose of improving the uniform dispersibility of the diisocyanate compound dimer and the uniform adhesion of the treatment liquid. When a thickener is not used in combination, the viscosity of the first treatment liquid becomes too low, and the fine particles of the diisocyanate dimer are likely to precipitate in the treatment liquid. Also, it becomes difficult to uniformly apply the treatment liquid to a cord or the like, and the adhesive strength is reduced or the dispersion is liable to occur. As a result, in order to stably achieve a sufficient adhesive strength, for example, the amount of adhesion must be increased, which is not preferable in terms of cost.

The concentration of the diisocyanate compound dimer in the first treatment liquid is suitably from 0.1 to 5.0% by weight.
The method of applying the first treatment liquid to the untwisted polyester fiber or twisted cord is arbitrary, but usually, the dipping method is employed. The solid content (active ingredient) conversion amount of the first treatment liquid is
0.4 in terms of adhesion amount of diisocyanate compound dimer
It is necessary to control within the range of ~ 1.5% by weight.
After adhering the first treatment liquid, the temperature is 180 to 240 ° C., preferably 2 to 240 ° C.
10-235 ° C., 60-180 seconds, preferably 90
Heat treatment for ~ 150 seconds. At this time, in order to improve the strength of the obtained cord, a tensile stress is applied to the polyester fiber or twisted cord (stretch rate is 1%).
~ 4.5%, preferably about 2% stretch)
Heat treatment is preferred.

The polyester fiber which has been subjected to the first bonding treatment is subjected to a desired twist in the case of a non-twisted yarn, and then subjected to a second bonding treatment with a second treatment liquid containing resorcinol-formalin latex (RFL). . RFL used here
Uses a novolak-type condensate obtained by reacting resorcinol and formalin (formaldehyde) at a molar ratio of 1 / 0.5 to 1 / 0.9 in advance, and further adding formalin as needed, to obtain a molar ratio of resorcinol and formalin. (R / F) is 1
It is preferable to adjust the value in the range of /0.5 to 1/4. The type of rubber latex need not be particularly limited. However, if the compounding ratio of rubber latex is too high, the tackiness of the second treatment liquid will be extremely high, and the cohesive force of the adhesive film will be too low, resulting in an unfavorable result. This tends to adversely affect the adhesiveness of the resulting fiber cord. Conversely, if the compounding ratio of the rubber latex is too low,
The resulting polyester fiber cord is likely to be hard, and the strength and fatigue properties are likely to be reduced. Therefore, resorcinol
The weight ratio of the active ingredient between the formalin condensate and the rubber latex in the former / latter ranges from 1/1 to 1/15, particularly preferably in the range from 1/5 to 1/15 (weight ratio of solids).

In the second treatment liquid, 10 to 20% by weight of a blocked polyisocyanate (for example, diphenylmethane diisocyanate blocked with ε-caprolactam) is added as a crosslinking agent to the amount of the RFL active ingredient. It is more preferable because the bonding performance is improved.

The method of applying the second treatment liquid is not particularly limited as in the case of the first treatment liquid, but usually an immersion method is employed. It is desirable that the amount of the active ingredient (in terms of solid content) attached to the second treatment liquid is controlled in the range of 1.0 to 2.0% by weight based on the weight of the fiber. The polyester fiber cord to which the second treatment liquid has been adhered has a temperature of 150 to 180 ° C.
For 0-150 seconds, let the cord dry without sagging,
Then, at a temperature of 180 to 240 ° C., preferably 210 to 24
Heat treatment is performed at 0 ° C. for 60 to 180 seconds, preferably 90 to 150 seconds. At this time, the polyester fiber cord, in order to reduce the heat shrinkage of the resulting treatment cord,
The relaxation rate is 0 to 1.5%, preferably 0.2 to 0.
It is preferable to perform a relaxation heat treatment while giving about 5% relaxation.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to practical examples. In the examples, the cord strength, the cord peeling adhesive strength, the pull-out adhesive strength and the fatigue property (strength retention) were measured by the following methods.

<Strength of cord> Using a 4D air chuck, a test length (cord length) of 250 mm was taken using an Instron 5565 type tensile tester (manufactured by Instron).
The breaking strength was determined at a tensile speed of 300 mm / min. 10
Times, and the average value was taken as the code strength.

<Cord Peeling Adhesive Strength> This shows the peeling adhesive strength between the treated cord and the rubber. Seven cords were buried near the surface of the rubber sheet, and held in a steam vulcanizer into which steam at a temperature of 150 ° C. had been injected for 20 minutes to be vulcanized. Next, the two cords at both ends were removed, and the remaining five cords were simultaneously stripped from the rubber sheet at a speed of 200 mm / min. The power (N) required for peeling was measured and indicated as N / 5 cords (N / 5C). .

<Pull-out adhesive force> It shows the shear adhesive force between the treated cord and the rubber. The cord was embedded in a rubber block, held in a steam vulcanizer into which steam at a temperature of 150 ° C. was injected, and vulcanized for 20 minutes. Next, the cord was pulled out from the rubber block at a speed of 200 mm / min, and the power (N) required for the drawing was measured and indicated in N / cm.

<Fatigue (Strength of retention)> Using a belt-type fatigue tester, a cord is sandwiched between two rubber sheets having a thickness of 2 mm, and a pressure of 50 kg / cm ² is applied under a pressure of 150 ° C. for 20 minutes. Vulcanize. 50 sheets obtained
The sample was cut into a belt shape having a width of 500 mm and a length of 500 mm. A load of 10 kg was applied to the sample, and the sample was mounted on a roller having a diameter of 20 mm. The remaining strength was measured, and the strength retention during fatigue was determined.

Example 1 First, an adhesive was prepared as follows. That is, Neocol S as a surfactant
2 g of W (sodium dialkyl sulfosuccinate: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., concentration: 30%) is added to 75 g of water, and 0.12 g of xanthogum powder is added to a well-mixed solution, followed by further stirring. Then, a dimer of tolylene diisocyanate (TSE, USA: trade name)
Thanecure T9 (concentration: 100%) (25 g) was added thereto and mixed well to obtain a dispersion. This was diluted 5-fold to obtain a first treatment liquid having a concentration of 5%.

Further, 20.1 g of Sumikanol 700S (resorcinol-formalin initial condensate, R / F = 1 / 0.6 (molar ratio), manufactured by Sumitomo Chemical Co., Ltd., concentration: 65%) and 426.7 g of water were stirred. Then, 5.1 g of aqueous sodium hydroxide solution (concentration 10%), 14.5 g of aqueous ammonia solution (concentration 28%), and aqueous formalin solution (concentration 3%)
(7%) 17.1 g is added, and the mixture is further slowly stirred and mixed. Next, JSR0652 (vinyl pyridine styrene
Butadiene rubber latex: manufactured by Takeda Pharmaceutical Co., Ltd.
(Concentration 40%) 422.8 g was added, and finally an aqueous dispersion of diphenylmethane diisocyanate blocked with ε-caprolactam (manufactured by EMS, trade name Grilbon)
(d, concentration: 50%), 61.8 g, and mix well to obtain a second treatment liquid. After the adjustment, it is aged for 24 hours in a room temperature atmosphere and used.

A polyglycidyl ether compound was previously added to the spinning oil in the spinning process, and three 1000-denier / 250-filament epoxy pre-treated polyester filaments (intrinsic viscosity 0.85; manufactured by Teijin Limited) were aligned. And a twist of 15T / 10 cm in the Z direction. Then, three strands of this twisted yarn are aligned and 9T in the S direction.
By applying a / 10 cm upper twist, a raw cord of 9000 denier was obtained. The obtained raw cord was immersed in the first treatment liquid using a contributor (tire code processing machine manufactured by CA Ritzler, Inc.), and then heat-treated at 235 ° C. for 150 seconds with a stretch ratio of 2.0%.

Next, after being immersed in the second treatment liquid, it is dried at 170 ° C. under a constant length for 150 seconds, and subsequently subjected to a heat treatment at 230 ° C. under a relaxation rate of 0.2% for 120 seconds.
An adhesive treatment code was obtained. In addition, the amount of each processing solution adhered is 1 to
It was adjusted to be 2% by weight. The obtained polyester fiber cord was converted into NR / natural rubber (NR) /
Using SBR rubber, vulcanization was performed at 150 ° C. for 20 minutes in a steam vulcanizer into which steam was blown to obtain a rubber composite.

Examples 2 and 3 and Comparative Examples 1 and 2
A rubber composite was obtained in the same manner as in Example 1 except that the type of isocyanate in the first treatment liquid and the RF / L of the second treatment liquid were changed as shown in Table 1. For these,
Table 1 shows the results of the measurement of the cord strength, the peel adhesive strength, the pull-out adhesive strength, and the cord strength retention after fatigue together with Example 1.
Shown in

[0026]

[Table 1]

[0027]

The polyester fiber cord obtained by the treatment method of the present invention maintains the excellent mechanical properties of the polyester fiber such as high strength, and has excellent adhesion to the matrix rubber of the rubber composite. Rubber composites such as belts reinforced with fiber cords have excellent dimensional stability, and have excellent power transmission and fatigue resistance.

Conventionally, isocyanate compounds have high reactivity and cannot be used as such in aqueous treatment agents.
A mechanism is employed in which the isocyanate group is blocked, and the blocking agent is released upon heating to exert the effect of the isocyanate. However, in the present invention, the diisocyanate dimer is decomposed into monomers by heating and acts as free diisocyanate, so that good adhesive performance can be obtained without blocking.

Claims (3)

[Claims] 1. A first treatment liquid containing a dimer of a diisocyanate compound in a non-twisted state or a twisted cord state on a polyester fiber to which an epoxy compound has been added in advance in a spinning stage, and a fiber weight in terms of an adhesion amount of the dimer. At a ratio of 0.4 to 1.5% by weight with respect to
After heat treatment at ~ 240 ° C for 60 to 180 seconds, twisting is applied to non-twisted yarn, then resorcinol / formalin /
Applying a second processing liquid containing rubber latex (RFL);
A method for treating a polyester fiber cord, comprising performing a heat treatment at a temperature of 180 to 240 ° C. for 60 to 180 seconds. 2. A dimer of a diisocyanate compound,
The method for treating a polyester fiber cord according to claim 1, which is a tolylene diisocyanate dimer. 3. The RFL contained in the second processing solution has a resorcin / formalin molar ratio (R / F) of 1 / 0.5 to 3.
It is composed of novolak type condensate (RF), formalin (F) and rubber latex (L) having a ratio of 1 / 0.9, and the active ingredient weight ratio ((RF + F) / L) is 1/5.
The second treatment liquid contains 10% of a blocked polyisocyanate compound based on the weight of the RFL active ingredient.
The method for treating a polyester fiber cord according to claim 1, which is contained in an amount of from 20 to 20% by weight.