JPH0442415B2 - - Google Patents

Description

[Detailed description of the invention]

(Object of the Invention) The present invention relates to a method for adhesion treatment of polyester fibers for rubber reinforcement, which has improved adhesion to rubber. (Background) Polyester fibers generally have excellent properties such as tensile strength and dimensional stability, and are suitable as rubber reinforcing materials for automobile tires, conveyor belts, V-belts, hoses, etc. However, since polyester fibers have poor adhesion to rubber, many proposals have been made to improve the adhesion. For example, polyester fibers are mixed with a polyester fiber containing a polyepoxide compound and an aromatic polyisocyanate compound.
A method (Japanese Patent Publication No. 11482/1982) is known in which the material is treated in a treatment bath and then treated in a second treatment bath containing resorcinol, formaldehyde, and rubber latex. The fibrous material treated by this method has the disadvantage that the fibrous material, which exhibits relatively excellent adhesion to rubber, becomes hard and difficult to bend during molding, and its fatigue resistance is significantly reduced. (Objective) Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks. (Structure) The object of the present invention is to treat polyester fibers for rubber reinforcement with a first treatment bath containing an aqueous solution of a polyepoxide compound, and then to treat them with a second treatment bath containing resorcinol, formaldehyde, rubber latex, a blocked polyisocyanate compound, and carbon black. This is achieved by doing. The method of the present invention will be described in more detail below. (Details of Structure) The polyester fiber used in the present invention means a yarn, cord, or woven fabric made of aromatic or naphthalene ring-containing linear polyester such as polyethylene terephthalate and polyethylene naphthalate. It goes without saying that the form of the polyester fiber varies depending on its use, but the treatment of the present invention can be performed in any form. For example, the yarn may be treated in the first treatment bath, then made into a cord or woven fabric, and then treated in the second treatment bath, or the yarn may be treated in the first treatment bath, then treated in the second treatment bath. It may be processed with The polyepoxide compound used in the first treatment bath of the present invention is a compound having two or more epoxy groups in one molecule, and is composed of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol, and epichlorohydrin. Examples thereof include reaction products of halogen-containing epoxides such as halogen-containing epoxides, and reaction products of polyhydric phenols such as resorcinol/formaldehyde resin and halogen-containing epoxides. Preferably, a reaction product obtained by reacting a polyhydric alcohol, such as glycerol, with epichlorohydrin is used. The first bath in the present invention is composed of an epoxide compound and water, and contains the epoxide compound in an amount of 0.5 to 15.0% by weight, preferably 2.0 to 10.0% by weight. Here, if the amount is outside the above range and the amount is too small, the rate of rubber adhesion to the treated polyester fibers will be poor, and if it is too much, the treated polyester fibers will become hard and the fatigue resistance will decrease. The blocked polyisocyanate compound used in the second treatment bath of the present invention is an addition compound of a polyisocyanate compound and a blocking agent,
The following are used: Examples of the polyisocyanate compound include polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and triphenylmethane triisocyanate. Examples of blocking agents include phenols such as phenol, cresol, and resorcinol; lactams such as caprolactam and valerolactam; oximes such as acetoxime and methyl ethyl ketone oxime; tertiary alcohols such as t-butanol and t-pentanol; It is ethyleneimine. The carbon black used in the second treatment bath of the present invention is preferably formulated as an aqueous dispersion using an arbitrary dispersant. Examples of carbon black include carbon blacks commonly used in the rubber industry with an average particle size of 11 to 500 mμ, such as SAF,
ISAF, HAF, GPF, FT, MT, EPC, MPC,
FF, SRF, etc. are used. The second treatment bath in the present invention contains (X) a mixture of an alkali-catalyzed resorcinol-formaldehyde initial condensate and rubber latex (RFL), (Y) a blocked polyisocyanate compound, (Z) carbon black, and (V) carbon black. It consists of a mixture consisting of a dispersant and (W) water. The second treatment bath is created, for example, by the following procedure. Obtain resorcinol/formaldehyde initial condensate (RF) with water, resorcinol, formaldehyde, and caustic soda. The condensate is poured into rubber latex to obtain a resorcinol/formaldehyde/rubber latex mixture (RFL). Meanwhile, water, caustic soda, dispersant, and carbon black are well dispersed to obtain a carbon black dispersion. A blocked polyisocyanate compound/carbon black dispersion is mixed with the resorcinol/formaldehyde/rubber latex mixture and stirred well to obtain a second treatment bath of resorcin/formaldehyde/rubber latex/blocked polyisocyanate compound/carbon black. 2. To prepare the treatment bath, a blocked polyisocyanate compound and carbon black can be added to the resorcinol/formaldehyde/rubber latex solution, and then aged and used.
Further, after aging the resorcinol/formaldehyde/rubber latex liquid, a blocked polyisocyanate compound and carbon black may be added immediately before processing the polyester fibers. Aging of resorcinol/formaldehyde/rubber latex is usually carried out at 20 to 30°C for 24 hours or more. The second treatment bath containing resorcinol, formaldehyde, rubber latex, blocked polyisocyanate compound, and carbon black usually has a solid content.
The content is adjusted to 15 to 25% by weight. The second treatment bath of the present invention is a mixed dispersion containing resorcinol/formaldehyde/rubber latex (X), blocked polyisocyanate compound (Y), and carbon black (Z), and the weight ratio of (X):(Y) is is 100:5
~100:30, preferably 100:10~100:25. [(X)+(Y)]:(Z) weight ratio is 100:0.3
-100:20, preferably in the range of 100:0.8 to 100:10. Here, if the weight ratio of (Y)/(X) is small, the rate of rubber adhesion to the polyester fibers during treatment will be poor. If it is too large, the treated polyester fiber becomes hard, leading to a decrease in fatigue resistance. If (Z)/[(X)+(Y)] is small, the rate of rubber adhesion to the treated polyester fibers will be poor. Even if it is made larger, it makes little contribution to improving the rubber adhesion rate of polyester fibers. Any method such as immersion in a liquid bath or spraying from a nozzle can be used to attach the first treatment bath and the second treatment bath to the polyester fibers. The amount of solid content deposited on the polyester fiber is 0.05 to 3.30% by weight for the first treatment bath composition, preferably 0.3 to 2.2% by weight, and 4.0% for the second treatment bath composition.
~7.0% by weight, preferably 4.5-6.0% by weight. If the amount of solid content attached is too low, the adhesive strength will decrease,
If the amount is too high, the adhesive-treated polyester fibers will become hard. In order to control the amount of solid content attached to the polyester fibers, means such as squeezing with a pressure roller, blowing off with air, suction, etc. may be used. In the present invention, polyester fibers are treated with the first treatment bath and then dried at a temperature of room temperature to 150°C.
Heat treatment at a temperature of ~250°C, preferably 180-220°C, then treated in a second treatment bath to a temperature of 60-150°C
Dry at a temperature of 200-260℃, preferably
Heat treatment at a temperature of 230-250℃. If the heat treatment temperature is too low, adhesion to the rubber will be insufficient, while if the heat treatment temperature is too high, the polyester fibers will melt and the strength will drop significantly, making it impossible to put it to practical use. Polyester fibers treated in this way have general properties such as excellent tensile strength and dimensional stability for rubber reinforcement, and are particularly flexible, have low bending hardness, have good moldability, and have excellent fatigue resistance. Excellent, and the rubber adhesion rate of polyester fibers is extremely high when subjected to a peel adhesion test after being embedded in compounded rubber and vulcanized. Although it is not clear why the present invention provides treated polyester fibers that are flexible and have an extremely high rubber adhesion rate, the bonding force between the polyepoxide compound in the first treatment liquid and the polyester fibers is greater than the carbon black contained in the second treatment liquid. It is thought that this is because the presence of carbon black strengthens the bond between the polyepoxide compound and the components contained in the second treatment liquid. Furthermore, if the mechanism is estimated from the characteristics of carbon black, it will be as follows. That is, functional groups extending over the surface layer of the particles, such as carboxyl groups,
The structural characteristics of the above treatment liquid include that carbonyl groups, quinone groups, hydroxyl groups, etc. react with the polyepoxide compound and blocked isocyanate compound that are the components of the treatment liquid to form strong chemical bonds, and that the particles have a large surface area. It is presumed that a strong adhesive bond can be obtained between the polyester fiber and the polyester fibers due to two mechanisms: increasing the number of contact points with each component and strengthening the cohesive force within the adhesive layer. be. The present invention will be explained in more detail below with reference to Examples. In the examples, the inter-ply peel force indicates the adhesive force between polyester fiber and rubber, and is 2
Cross-ply (cord density 30
The force required to peel the ply at a tensile speed of 50 mm/min after embedding it in carcass compound rubber for automobile tires as end/25 mm and vulcanizing it by pressing at 150°C for 30 minutes is expressed in Kg/20 mm. be. Rubber adhesion rate is also a measure of the adhesion of rubber to polyester fibers.The cord that has been peeled off from the rubber during the inter-ply peel force measurement described above is observed with the naked eye, and the portion of the cord surface where rubber is adhered is graded into five grades. [A (rubber adhesion rate 81-100%), B (rubber adhesion rate 61-80%), C (rubber adhesion rate 41-60%), D (rubber adhesion rate 21-40%), E (rubber adhesion rate 20% or less)] and represented by symbols. The bending hardness of the cord is measured using a taper method, and the higher the measured value, the harder it is. Furthermore, strength retention is a measure of fatigue resistance, and is expressed as a percentage of the strength remaining after 48 hours (1705 rpm) of cyclic fatigue of 5% elongation and 10% compression applied to the cord between rotating discs using a Gutdoritsu disc tester. This is what is expressed. Example 1 995 g of distilled water to 5 g of Criserol polyglycidyl ether (Decor EX-314 manufactured by Nagase Sangyo Co., Ltd.)
was added and dissolved uniformly, and the resulting aqueous solution was used as the first treatment bath. Meanwhile, distilled water 360.48g, resorcinol 18.9g, 37
An initial condensate of 27.67 g of % formaldehyde and 51 g of a 1% aqueous solution of caustic soda was prepared, and the condensate was mixed into a vinylpyridine-styrene-butadiene terpolymer latex (manufactured by Nippon Zeon Co., Ltd., Nitzpol).
2518FS40.5% emulsion) 422.99g, 28% ammonia
Add 19.45g and 114.2g of distilled water to a mixture while stirring gently and age for 24 hours. After the aging is completed, the resorcinol/formaldehyde/rubber latex mixture is mixed with a phenol block product of diphenylmethane/diisocyanate (Hylene manufactured by Dupont).
Add and disperse 80 g of a 25% aqueous dispersion of MP). Next, 24 g of distilled water, 5 g of 1% caustic soda, 1.0 g of sodium ligninsulfonate, and 10 g of carbon black (HAF, manufactured by Asahi Carbon Co., Ltd.) were dispersed in a ball mill for 48 hours, and then 1.2 parts of the dispersion was mixed with resorcinol/formaldehyde, rubber latex, and block. The mixed solution obtained by adding and mixing the dopolyisocyanate compound mixture is used as a second treatment bath. 1500D/2 strands combined, top twist 40 times/10cm, bottom twist 40
After immersing a cord made of polyester fibers of 10 cm/time in the first treatment bath using a computer treater (manufactured by C.A. Ritzler),
Dry at 100°C for 150 seconds, followed by heat treatment at 200°C for 30 seconds. Then 100℃ after immersion in the second treatment bath
for 150 seconds, followed by heat treatment at 245°C for 60 seconds. The treated polyester cord was coated with resin having a solid content of 0.05% by weight from the first treatment bath and 4.8% by weight from the second treatment bath. The resulting treated cord was measured for interply peel strength, rubber adhesion rate, cord strength, cord bending hardness, and strength retention after fatigue. The results are shown in Table 1. In Examples 2 to 18, the total solid concentration of the polyepoxide compound in the first treatment bath was changed, and the mixing ratio of the blocked polyisocyanate compound and carbon black in the second treatment bath was also changed. For comparison, Comparative Example-1 is obtained by removing the polyepoxide compound in the first processing bath from the Example, Comparative Example-2 is obtained by removing the blocked polyisocyanate compound in the second processing bath, and Carbon Black in the second processing bath is obtained. Comparative Example 3 was obtained by excluding the following. Results first
Also shown in the table. In the present invention, polyester fibers treated with a first treatment bath containing an aqueous solution of a polyepoxide compound, and then treated with a second treatment bath containing resorcinol, formaldehyde, rubber latex, blocked polyisocyanate compound, and carbon black are flexible and have excellent fatigue resistance. It can be seen that the rate of rubber adhesion to polyester fibers is excellent.

【table】

[Table] Nate compounds, (Z) indicates carbon black.
Further, Examples 19 to 22 were the same as Example 3 except that the blocked polyisocyanate compound was variously changed, and the results of cord processing are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1. Processing polyester fibers for rubber reinforcement with a first treatment bath containing an aqueous solution of a polyepoxide compound, and then treatment with a second treatment bath containing resorcinol, formaldehyde, rubber latex, blocked polyisocyanate compound, and carbon black. Characteristic adhesive treatment method for polyester fibers for rubber reinforcement. 2. The adhesive treatment method for polyester fibers for rubber reinforcement according to claim 1, wherein the first treatment bath contains 0.5 to 15.0% by weight of a polyepoxide compound. 3 The second treatment bath is resorcin formaldehyde.
Rubber latex mixture (X), blocked polyisocyanate compound (Y) and carbon block (Z) at weight ratio (X):(Y) of 100:5 to 100:30, [(X)+(Y)]: (Z)
in
A method for adhesion treatment of polyester fibers for rubber reinforcement according to claim 1, wherein the ratio is from 100:0.3 to 100:20.