JPH09241975A - Treatment of polyester fiber cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester fiber-treated cord highly adhesive to rubber in high productivity, by using an adhesive composition comprising a water-based mixed liquid composed of a resorcin-formaldehyde initial condense and rubber latex and a specific aqueous dispersion of epoxy resin. SOLUTION: First, an adhesive composition is prepared by blending a water- based mixed liquid composed of a resorcin-formaldehyde initial condense and rubber latex with an aqueous dispersion of a water-insoluble cresol novolak type epoxy resin in the weight ratio (on a solid basis) of (100:15) to (100:120). Thereafter, a polyester fiber cord is impregnated with the above adhesive composition, dried under a tension of 0.15-0.6g/d at 60-180 deg.C and then heat-set at 200-260 deg.C within the tension range satisfying the relationship: 0.50<=HS/D<=2.00 [HS is heat-set tension (g/d); D is dry tension (g/d)], thus obtaining the objective treated cord.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a tire, a belt,
The present invention relates to an advantageous treatment method for polyester fiber cords used in rubber articles such as hoses.

[0002]

2. Description of the Related Art Polyester fiber cords have low adhesion to rubber. Therefore, in order to enhance this adhesiveness, conventionally,
After pre-treating the polyester fiber cord with epoxy resin or blocked isocyanate, it is further treated with a water-based mixture (RFL) of resorcinol / formaldehyde initial condensate and rubber latex, or p-chlorophenol / resorcinol. A so-called two-bath treatment method is performed, in which a polyester fiber cord is treated with an aqueous solution containing a formaldehyde condensate (for example, Denabond manufactured by Nagase Kasei Co., Ltd.) or an allyl hydroxyphenyl ether / formaldehyde condensate, and then subjected to RFL treatment. . However, in this two-bath treatment method, in addition to the dipping step in each bath treatment, a drying step and a high-temperature heat treatment step have to be performed, so that an extremely complicated procedure in which the heat treatment has four steps is required, resulting in remarkably high productivity. There is a problem of being inferior. Furthermore, there are drawbacks in that the economical efficiency is inferior because a large number of heat treatment furnaces are required and the equipment cost is high.

As a method for simplifying such a two-bath treatment, the above-mentioned p-chlorophenol / resorcinol / formaldehyde condensate or allyl hydroxyphenyl ether.
There is also a one-bath treatment method in which a polyester fiber cord is treated with a liquid in which a formaldehyde condensate is added to RFL. However, in this method, since the condensate is an aqueous ammonia solution, an odor problem occurs and the environment is deteriorated. There is a problem. Further, there is a problem that this one-bath treatment method is not satisfactory in terms of adhesion between the polyester fiber cord and the rubber.

Also in the one-bath treatment method, in order to enhance the dimensional stability of the cord when the polyester fiber cord is embedded in the rubber and bonded and integrated by vulcanization, the polyester fiber cord is immersed in an adhesive liquid and then dried and heat treated. Further, a treatment method has been proposed in which tension treatment by heat set heat treatment and then relaxation treatment by normalizing heat treatment are performed (for example, Polymer no Tomo (Taiseisha), 12 , p507, 1984, Japanese Patent Publication No. 7-1712).
No. 5, Japanese Patent Publication No. 7-91716). However, even in this treatment method, there is a problem that productivity is inferior because the heat treatment must be performed in at least three stages.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a treatment method for obtaining a polyester fiber cord having high productivity, high adhesion between the polyester fiber cord and rubber, and good dimensional stability. That is.

[0006]

The method for treating a polyester fiber cord according to the present invention comprises a water-based mixture (a) of a resorcin / formaldehyde precondensate and a rubber latex having a melting point of 40 ° C. or higher and an epoxy equivalent of 300. The following is also an aqueous dispersion of a substantially water-insoluble epoxy resin
An adhesive composition obtained by mixing (b) is impregnated and adhered to a polyester fiber cord, and the cord is then 0.15 g / d to 0.
It is characterized in that it is obtained by tension drying at a temperature of 60 ° C. to 180 ° C. under a tension of 6 g / d, and then heat setting at a temperature satisfying the following formula at a temperature of 200 ° C. to 260 ° C. 0.50 ≦ HS / D ≦ 2.00 HS: Heat set tension (g / d), D: Drying tension (g / d) Thus, the polyester fiber cord is treated with a specific adhesive composition in one bath By further specifying the temperature, the drying tension and the heat setting tension during the treatment, not only the adhesion between the polyester fiber cord and the rubber is enhanced, but also the polyester fiber excellent in dimensional stability and processability is obtained. It is possible to get the code. Further, by embedding the treated polyester fiber cord in unvulcanized rubber and integrally vulcanizing it, a rubber article such as a tire, a belt or a hose can be obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Polyester fiber cord An ordinary cord may be used. This polyester fiber cord has
For example, in addition to cords of polyester fibers such as polyethylene terephthalate fibers, polyethylene 2, 6 naphthalate fibers, polybutylene terephthalate fibers, and the like, cords of composite fibers of these fibers and other organic fibers are also included. (2) Adhesive composition Aqueous mixture (a) of resorcinol / formaldehyde initial condensate and rubber latex, which has a melting point of 40 ° C or higher and an epoxy equivalent of 300 or lower, and is substantially water-insoluble. It is prepared by mixing an aqueous dispersion (b) of resin.

(A) Aqueous mixture of resorcinol-formaldehyde precondensate and rubber latex (ie RF
L) For the resorcin-formaldehyde initial condensate used for RFL, resorcin and formalin aqueous solution are dissolved in water, and an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added as a catalyst to resorcin and formalin. There is a resol type reaction product obtained by reacting ## STR2 ## or a novolak type reaction product of resorcin and formalin reacted under an acidic catalyst such as oxalic acid or hydrochloric acid, but any one may be used. Examples of the novolac type initial condensate include Sumikanol 700 manufactured by Sumitomo Chemical Co., Ltd. and Adhar RF manufactured by Hodogaya Chemical Co., Ltd.
Are commercially available. When these novolac type resorcin-formalin resins (RF resins) are used, a small amount of alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is used to dissolve the resin in water. When these novolac type RF resins are used, a formalin aqueous solution is usually added later.

Further, it is more preferable that the alkali metal hydroxide contained in the adhesive composition is 2.0% or less and 0.05% or more with respect to the total adhesive solid content of the adhesive composition. . When the content of the alkali metal hydroxide contained in the adhesive composition exceeds 2.0%, especially in the adhesion between the polyester fiber cord and the rubber, the hydrolysis of the polyester fiber cord using the alkali metal hydroxide as a catalyst is performed. As a result of easy decomposition, heat resistant adhesion deteriorates. On the other hand, when it is less than 0.05%, the novolac-type resorcinol-formaldehyde initial condensate becomes particularly difficult to dissolve in water. Also, RFL
It takes a long time to ripen and the productivity is deteriorated.

The rubber latex is appropriately selected depending on the type of unvulcanized rubber (adhered rubber) used for adhesion to the treated polyester fiber cord. For example, natural rubber,
For general-purpose rubbers such as SBR, IR and BR, vinyl pyridine / styrene / butadiene terpolymer latex, SBR latex and natural rubber latex are used. From the viewpoint of adhesiveness, it is preferable to use vinyl pyridine / styrene / butadiene terpolymer latex, but SBR latex or natural rubber latex can be appropriately mixed and used. When the adhered rubber is CR or NBR, CR latex or NBR latex, or a mixture of these with vinyl pyridine / styrene / butadiene terpolymer latex can be used. The rubber latex can be appropriately selected depending on the use.

(B) Aqueous dispersion of an epoxy resin having a melting point of 40 ° C. or higher and an epoxy equivalent of 300 or lower, and is substantially water-insoluble. The epoxy resin used here is, for example, a polyphenol type epoxy resin. Is. Examples of polyphenol type epoxy resins include phenol novolac type, cresol novolac type, hydroquinone type, biphenyl type, bisphenol S type, brominated novolac type, xylene modified novolac type, phenol glyoxal type, trisoxyphenylmethane type, trisphenol. PA
Type, bisphenol A novolac type epoxy resin. The epoxy resin may be selected from the above, but a cresol novolac type epoxy resin is preferable from the viewpoint of adhesiveness and versatility.

The epoxy resin used here is a substantially water-insoluble epoxy resin (water-insoluble epoxy resin).
It is. Water-soluble epoxy resins obtained from the reaction of epichlorohydrin and polyols that are usually used for the adhesion treatment of fibers and rubbers (for example, Denacol EX313, EX614, EX512 manufactured by Nagase Kasei Co., Ltd.) are excluded. These are because when added to RFL, the epoxy resin reacts with the RF resin due to its water solubility, resulting in gelation of the adhesive composition and deterioration of the adhesiveness. Further, even a water-insoluble epoxy resin, a liquid epoxy resin having a melting point of less than 40 ° C. at room temperature is excluded. Furthermore, the epoxy equivalent is 300
Anything over is excluded.

The melting point of 40 ° C. or higher is for solidification at room temperature. That is, since the adhesive composition of the present invention is usually used at room temperature and exposed to an environment of 5 ° C to 40 ° C, an epoxy resin which is liquid in a temperature atmosphere during use is left mixed with RFL. This is because it reacts with the RF resin to cause gelation of the adhesive composition and decrease in adhesion. This is because the RF resin is dissolved in water, so that when the epoxy resin is dispersed in the water in a liquid state, it is more likely to react with the RF resin than when it is dispersed in a solid state. Therefore, it is essential to select an epoxy resin that does not cause liquefaction due to thermal softening at a normal use environment temperature of less than 40 ° C.

The epoxy equivalent of the epoxy resin is 30.
It must be 0 or less. The epoxy equivalent is the molecular weight per epoxy group of the epoxy resin. When the epoxy equivalent is more than 300, sufficient adhesion cannot be obtained because the number of epoxy groups that react substantially with the fibers of the polyester fiber cord is small. From the viewpoint of improving adhesiveness, the epoxy equivalent is more preferably 250 or less.

Further, it is preferable that the aqueous dispersion of these epoxy resins contains substantially no organic solvent. This is because, in order to disperse these epoxy resins in water, a method of once dissolving the epoxy resin in an organic solvent such as toluene and water-dispersing it with an appropriate dispersant is performed. However, as described above, when it is dispersed in water as a liquid, there is a problem that the reaction with the RF resin is likely to occur and the adhesiveness is lowered, and when mixed with RFL, the epoxy resin causes cohesive precipitation. Because it is easy.

Here, as a method for obtaining an aqueous dispersion containing substantially no organic solvent, a known method can be used. For example, an epoxy resin that is solid at room temperature is heated to a temperature higher than the thermal softening temperature to bring it into a molten state, hot water and a dispersant are mixed and stirred, and then passed through a colloid mill for further miniaturization. This method can be applied to an epoxy resin that melts below the boiling point of water. When an epoxy resin having a high heat softening temperature is used, the epoxy resin is dissolved in an organic solvent in which the epoxy resin is soluble, water and a dispersant are added, and a predetermined stirring device having a high shearing force is used. Mix and stir to disperse. Furthermore,
In order to remove the organic solvent, vacuum distillation is carried out to obtain an aqueous dispersion of the epoxy resin containing substantially no organic solvent. Alternatively, it is also possible to disperse mechanically finely pulverized epoxy resin in water by using a dispersant so that the epoxy resin is not softened by heat.

The dispersant used here is preferably a known nonionic dispersant or anionic dispersant. Although it is possible to use a cationic dispersant, it is not preferable because it causes gelation when added to RFL. further,
It is more preferable that the dispersion average particle diameter of the epoxy resin is 5 μm or less. If the average particle size exceeds 5 μm, the dispersion stability is poor, and the epoxy resin tends to settle when the adhesive is used,
In some cases, sufficient adhesion may not be obtained. Therefore, in order to obtain more stable adhesion, it is preferable to set the average particle diameter to 5 μm or less.

(C) The solid content mixing ratio (parts by weight) of the solid content of RFL and the solid content of the aqueous dispersion of epoxy resin is 1
A range of 00:15 to 100: 120 is used. If the solid content of the aqueous dispersion of epoxy resin is less than 15 parts by weight, good adhesion cannot be obtained. Further, even if the solid content of the aqueous dispersion of the epoxy resin exceeds 120 parts by weight, the adhesiveness is deteriorated, and the cord becomes hard and fatigue resistance and workability are deteriorated. 100: 20 to 100: 100 are more preferable in terms of adhesiveness and workability. (3) In the present invention, after the polyester fiber cord is impregnated with the adhesive composition thus blended and adhered, the cord is tensioned at 0.15 g / d to 0.6 g / d at 60 ° C. to 180 ° C.
Tension drying is performed at a temperature of ℃, and then heat set at a temperature of 200 to 260 ℃ with a tension satisfying the following formula. 0.50 ≦ HS / D ≦ 2.00 HS: Heat set tension (g / d), D: Drying tension (g / d) Here, the drying tension D is the tension at the temperature of 60 ° C. to 180 ° C.
0.15 g / d to 0.6 g / d, heat set tension HS is above
The tension when heat-setting at a temperature of 200 to 260 ° C.

RFL when the drying temperature is less than 60 ° C.
Because the epoxy resin dispersed in it does not melt sufficiently,
The adhesion of the adhesive composition to the polyester fiber cord becomes non-uniform, and the adhesion between the polyester fiber cord and the rubber tends to vary. In addition, the drying time becomes long and productivity deteriorates. On the other hand, if it exceeds 180 ° C., blister (foaming) is likely to occur on the surface of the adhesive layer, which causes a decrease in adhesion. 80 ° C. to 150 ° C. is suitable as the drying temperature.

Further, the tension applied to the cord during the drying treatment is 0.
If the amount is less than 15 g / d, the adhesive composition excessively permeates the inside of the polyester fiber cord, resulting in a decrease in strength. on the other hand,
If it exceeds 0.60 g / d, the friction between the guide device and the adhesive treatment cord in the drying treatment step becomes large, so that not only the guide device is soiled but also the adhesiveness is deteriorated. Further, the bending hardness of the cord is remarkably increased, resulting in deterioration of workability and fatigue resistance. Tension D is 0.20 to 0.40g
/ D is more preferable.

Further, the temperature of the heat setting process is 200
If the temperature is lower than 0 ° C, sufficient adhesion between the polyester fiber cord and the rubber cannot be obtained, and if the temperature exceeds 260 ° C, the cord melts. This temperature is more preferably 230 to 245 ° C. Here, when the ratio HS / D of the heat setting tension HS and the drying tension D is less than 0.50, the cord is flexible but the cord strength decreases, and at the same time the dimensional stability of the cord decreases. On the other hand, if it exceeds 2.00, not only the cord becomes extremely hard but also the adhesiveness is deteriorated. HS / D is 0.7
5 to 1.50 are more preferable.

[0022]

EXAMPLE An orthocresol novolac type epoxy resin (epoxy equivalent: 230, melting point: 85 ° C.) was used, and an anionic surfactant was added thereto to prepare an aqueous dispersion by a conventional method. The solid content is 40% by weight, and the average particle size of the dispersed particles is 4 μm. A mixture of this epoxy resin aqueous dispersion and RFL in the compounding amounts (parts by weight) shown in Table 1 was used as the adhesive liquid A. In this case, the solid content mixing ratio (parts by weight) of RFL and epoxy resin is 100: 30.

On the other hand, as a conventional example of a one-bath method adhesive composition, P-chlorophenol / resorcinol / formaldehyde condensate Denabond (trade name) manufactured by Nagase Kasei Kogyo and RFL are blended in amounts shown in Table 1 ( Adhesive liquid B was used as a mixture. In this case, the solid content mixing ratio (parts by weight) of Denabond and RFL is 40: 100.

[0024] Note) ^{* 1} Sumitomo Chemical Co., Ltd. resorcin / formaldehyde initial condensate, solid content 75% (novolak type RF resin). ^{* 2} Nippon Zeon Co., Ltd. vinyl pyridine / styrene / butadiene terpolymer latex, solid content 40%. ^{* 3} Orthocresol novolak epoxy resin water dispersion, solid content 40%. ^{* 4} P-chlorophenol-resorcinol-formaldehyde condensation product manufactured by Nagase Kasei Co., Ltd., solid content 20%.

For each of these adhesive liquids A and B,
The 1500D / 2 polyester cord was dipped, dried and heat-treated in a heat treatment furnace under the tension conditions shown in Tables 3 and 4. In this case, the conventional example 1, the comparative example, and the example were all subjected to a two-step treatment at a drying temperature of 130 ° C. and a heat setting temperature of 235 ° C. The treatment time was 1 minute each. Further, as Conventional Example 2, the adhesive solution B, which is a conventional one-bath treatment method, was used, and a three-step treatment of a drying temperature of 130 ° C., a heat setting temperature of 235 ° C., and a normalizing temperature of 235 ° C. was also performed as a heat treatment. The processing time is 1 minute each. The tensile strength N, Gurley bending index, dimensional stability index, and adhesive strength of the treated cords thus treated were evaluated by the following methods. The results are shown in Tables 3 and 4.

[0026] Tensile strength N : In accordance with JIS L1017 chemical fiber tire cord test method. Larger numbers are better.

Gurley Bending Index : Bending hardness was measured by aligning two cords according to the Gurley bending test method of JIS L1096. Displayed as an index with Comparative Example 1 being 100. If the bending hardness is high, the workability of forming tires, hoses, and the like will be problematic. Therefore, the smaller the index value, the better the flexibility.

Dimensional stability index : The sum of the elongation at 2.25 g / d and the dry heat shrinkage at 150 ° C. of the treated cord measured in accordance with JIS L1017 was calculated, and the comparative example 1 was set as 100 and indicated as an index. The smaller the index value, the better the dimensional stability. Adhesive force : According to JIS L1017, the treated cord was embedded in the unvulcanized rubber composition shown in Table 2, and after vulcanizing at 148 ° C. for 30 minutes, the adhesive force for pulling out the cord from the rubber was measured, and Comparative Example 1 Was expressed as an index. The larger the index value, the better.

[0029] * The tension of the normalizing heat treatment was set to 1/2 of the heat set tension (HS) for relaxation treatment.

[0030]

As is clear from Tables 3 and 4, the adhesive liquid A is compared with the one using the conventional adhesive liquid B (conventional examples 1 and 2).
Those using (Examples 1 to 6) all show clearly high adhesive strength. Further, in the conventional example, the reason why the adhesion of the conventional example 1 is lower than that of the conventional example 2 is that the heat treatment time is insufficient because the adhesive liquid B is used. Adhesive liquid A of the present invention
The one using (1) has good adhesion even if the normalizing heat treatment is omitted.

When the drying tension is less than 0.15 g / d (Comparative Example 1) even when treated with the adhesive liquid A, the cord strength (tensile strength N) is decreased, while the strength is 0.60 g / d. It can be seen that in the case of exceeding (Comparative Example 2), the bending hardness (Gurley bending index) remarkably increases and the adhesive force also decreases. Within the range of the processing conditions of the present invention, the cord strength is high, the cord is flexible, the cord dimensional stability is good, and the adhesion is good.

Further, when the HS / D ratio is less than 0.50 (Comparative Example 3), the cord is flexible, but the cord strength is low and the dimensional stability of the cord is not improved. On the other hand, 2.00
If it exceeds (comparative example 4), not only the cord becomes extremely hard but also the adhesive strength is reduced. On the other hand, when the HS / D ratio is in the range of 0.5 to 2.0, the cord strength is high, the cord is flexible, and the cord dimensional stability and adhesiveness are excellent.

[0034]

As described above, according to the present invention, it is possible to perform one-bath treatment as compared with the conventional two-bath treatment which is required for the adhesion treatment of the polyester fiber cord to the rubber. Without conventional at least drying treatment,
Compared with the case where three heat treatments of heat setting treatment and normalizing treatment were required, the present invention enables treatment with only two heat treatments of dry heat treatment and heat set heat treatment, so energy saving, productivity, It is possible to significantly improve equipment costs. Furthermore, according to the present invention, the adhesiveness between the polyester fiber cord and the rubber can be enhanced. Therefore, it becomes possible to provide rubber articles such as tires, conveyor belts and hoses using polyester fiber cords with good quality and at low cost.

Claims (3)

[Claims] 1. A water-based mixture (a) of a resorcin / formaldehyde precondensate and a rubber latex, which has a melting point of 40 ° C.
Or more and the epoxy equivalent is 300 or less,
An adhesive composition obtained by mixing an aqueous dispersion (b) of a substantially water-insoluble epoxy resin is impregnated and adhered to a polyester fiber cord, and the cord is then applied at 0.15 g / d to 0.6 g / d. Tension-dry under tension at a temperature of 60 ° C-180 ° C, then 200-
A method for treating a polyester fiber cord, which is obtained by heat-setting at a tension of satisfying the following formula at a temperature of 260 ° C. 0.50 ≦ HS / D ≦ 2.00 HS: Heat set tension (g / d), D: Drying tension (g / d) 2. The solid content mixing ratio (parts by weight) of the solid content of the aqueous mixture (a) and the solid content of the aqueous dispersion (b) is 10.
The method for treating a polyester fiber cord according to claim 1, which is in the range of 0:15 to 100: 120. 3. The method for treating a polyester fiber cord according to claim 1, wherein the epoxy resin is a cresol novolac type epoxy resin.