JPH0726029A - Cord-rubber composite and its production - Google Patents

Abstract

PURPOSE:To obtain a cord-rubber composite exhibiting an improved adhesion between reinforcing fiber and rubber and an excellent reinforcing effect by coating a cord of a specifically twisted PBO or PBT fiber with an epoxy compd. and then with a mixture comprising a resorcin-formaline precondensate and a rubber latex and burying the coated cord in a rubber matrix. CONSTITUTION:A PBO(poly-p-phenylene benzobisoxazole) or PBT(poly-p- phenylene benobisthiazole) is twisted to a number of twist of 0-2,500 to give a cord. The cord is impregnated with an aq. soln. or dispersion of an epoxy compd., heated at 160-250 deg.C, then impregnated with a mixture comprising a resorcin-formalin precondensate and a rubber latex, and dried at 160-250 deg.C). Thus treated cord is buried in a rubber to give a cord-rubber composite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cord / rubber composite having a highly excellent reinforcing effect and a method for producing the same.

[0002]

2. Description of the Related Art Among fibers consisting of aromatic ring-containing aromatic polymers, polyparaphenylenebenzbisoxazole (PBO) fibers and polyparaphenylenebenzbisthiazole (PBT) fibers are aramid fibers (aromatic polyamide fibers). It has about twice the strength and tensile elasticity.
Therefore, these PBO fibers or PBT fibers are used for tires,
If it can be used as a reinforcing material for rubber products such as conveyor belts, it will have a higher reinforcing effect while reducing the amount of aramid fiber used compared to the case of aramid fiber.
It can be expected that the weight of the cord / rubber composite will be reduced.

However, these PBO fibers or P
Since the cord of the BT fiber is inactive with respect to rubber due to its molecular skeleton, there is a problem that the adhesiveness with rubber is poor, so that it was difficult to realize.

[0004]

The object of the present invention is to provide a PB
An object of the present invention is to provide a cord / rubber composite having improved adhesiveness of O fiber or PBT fiber with rubber and having an excellent reinforcing effect, and a method for producing the same.

[0005]

The cord / rubber composite of the present invention has a polyparaphenylenebenzbisoxazole fiber (PBO fiber) or polyparaphenylenebenzbisthiazole fiber (PBT fiber) in which K = T√D (however, , T is the number of twists per 10 cm of cord, and D is the total number of denier. Twist has a twist coefficient K in the range of 0 to 2500. It is characterized in that it is embedded in a rubber matrix through a mixed composition coating composed of a substance and a rubber latex.

Further, the cord / rubber composite of the present invention is produced by the following method: polyparaphenylene benzbisoxazole fiber (PBO fiber) or polyparaphenylene benzbis thiazole fiber (PBT fiber) K = T√D (however, T is the number of twists per 10 cm of cord, and D is the total number of denier. Twist is added so that the twist coefficient K is in the range of 0 to 2500 to make a cord, and an aqueous solution or dispersion of an epoxy compound is added to this cord. After impregnating the cord, the cord should be kept at 160 ℃ -25
After heating at a temperature of 0 ° C and then immersing in a mixture of resorcin-formalin initial condensation product and rubber latex, 1
It is characterized in that the cord is heated at a temperature of 60 ° C. to 250 ° C., and then the cord thus treated is embedded in rubber.

As described above, in the present invention, since the cord of PBO fiber or PBT fiber which has been subjected to a predetermined treatment is used,
It is possible to improve the adhesiveness between the cord and the rubber. Hereinafter, the configuration of the present invention will be described in detail. (1) Cord The cord used in the present invention has a twist coefficient K in the range of 0 to 2500, preferably in the PBO fiber or PBT fiber, as described above.
It is a cord that is twisted so that it is in the range of 150 to 2000. PBO fiber is a polyparaphenylene benzbisoxazole having the following chemical structure as a constitutional unit.
It is a (PBO) fiber.

[0008] Further, the PBT fiber is a fiber of polyparaphenylenebenzbisthiazole (PBT) having the following chemical structure as a constitutional unit.

[0009] The twist coefficient K is set in the range of 0 to 2500, because if it is too large, the high strength and high elastic modulus characteristics of the PBO fiber and PBT fiber cannot be utilized. For example, near K = 0 is suitable for a reinforcing cord that constitutes a rubber hose, and K = 2500.
The vicinity is suitable for the carcass cord of the tire. K is 2500
If it exceeds, the rigidity of the cord will be too high.

The cord thus twisted is subjected to the following two-step treatment in order to improve the adhesiveness with rubber. That is, first, after impregnating an aqueous solution or dispersion of an epoxy compound, heating it at a temperature of 160 ° C to 250 ° C (first stage treatment), and then dipping it in a mixed liquid of resorcin / formalin initial condensate and rubber latex. After 160
A process of heating at a temperature of ~ 250 ° C (second stage process) is performed.

The epoxy compound used in the first stage treatment is 1
Those having at least one, and preferably two or more epoxy groups in the molecule are preferable. This epoxy compound is
It is obtained by subjecting the reaction product of polyhydric alcohol or polyhydric phenol and epichlorohydrin to alkali treatment. As the polyhydric alcohol at this time, for example,
Glycerin, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, hexatriol, polyacrylic alcohol, polyvinyl alcohol, inositol, trimethylolpropane,
1,4-dimethylolbenzene or the like is used. As the polyhydric phenol, for example, resorcin, hydroquinone, bisphenol A, phlorogricinol, catechol and the like are used. This epoxy compound is used as an aqueous solution or an aqueous dispersion which is dissolved or dispersed in water. The epoxy compound is preferably a bifunctional or higher functional one having an aromatic ring. PBO or PBT with aromatic ring
This is because it has a chemical structure similar to that of, and thus has an increased affinity for them. It is more preferable to use the rubber latex and its cross-linking agent together with the epoxy compound.

A mixed liquid (RF) used in the second-stage treatment, which comprises resorcin / formalin initial condensate and rubber latex.
As L), those usually used for bonding rubber and tire cord may be used. Examples of the rubber latex include natural rubber, styrene-butadiene copolymer rubber, vinylpyridine / styrene / butadiene copolymer rubber, NB.
It is an aqueous dispersion of rubber such as R and chloroprene rubber. RF
It is preferable to add an aziridine compound, a blocked isocyanate, or the like to L.

Further, the heating temperatures of the first-stage treatment and the second-stage treatment were set at 160 ° C. to 250 ° C., but if the temperature was lower than 160 ° C., the adhesive strength could not be sufficiently obtained, while if the temperature exceeded 250 ° C. This is because the epoxy compound and RFL are oxidized and deteriorated and the adhesive strength is reduced. For each heating, the cord is 0.2g / d ~
It is preferable to perform it while applying a tension of 2.0 g / d. (2) Rubber A usual rubber composition that constitutes a rubber product such as a belt layer of a tire, a carcass layer, a conveyor belt and a hose may be used. That is, for natural rubber, styrene-butadiene copolymer rubber, chloroprene rubber, NBR, and the like,
It is a mixture prepared by compounding agents such as carbon black and sulfur. It is preferable to blend a resorcin-formalin resin (RF resin) and a methylene donor into this rubber composition.

(3) The cord / rubber composite of the present invention comprises the cord embedded in the rubber. This cord-rubber composite can be obtained by embedding the cord in the unvulcanized rubber and vulcanizing and integrating it by a conventional method. The form of the cord used in this case may be a single form of the cord, or may be a sloping shape or a woven shape.

[0015]

Example: First-stage treatment liquid (parts by weight) shown in Table 1 for PBO fiber cord (1000D / 2, 35 × 35, twist coefficient K = 1565)
Using the second stage treatment liquid (parts by weight) shown in Table 2 and applying a tension (g / d), heat treatment was performed. Table 3 shows the values of temperature and tension in this case. In addition, in the first-stage treatment and the second-stage treatment, a drying treatment (120 ° C. × 0.2 g / d) was performed prior to heating.

[0016] Note) EX313 glycerol polyglycidyl ether, bifunctional, manufactured by Nagase Kasei Kogyo Co., Ltd.

EX614 sorbitol polyglycidyl ether, 3.6-functional, manufactured by Nagase Chemicals Co., Ltd. EM125 Epoxy Cresol Novolac Resin Emulsion, 25% total solids, manufactured by Nagase Chemicals Co., Ltd. * Nippon Zeon 2518FS (Vp latex) (40%). ** Meisei Chemical Industry DM30 (ε caprolactam blocked-MD1) (30%).

[0018] Note) * Sumikanol 700 (75%), Sumitomo Chemical Co., Ltd.
Made. ** Nipol 2518FS (40%), manufactured by Nippon Zeon Co., Ltd. *** Millionate MEW (26%) (diphenylmethane-bis-4,4'-N, N-diethyleneurea), manufactured by Nippon Polyurethane Industry Co., Ltd. Next, the cord thus treated was embedded in an unvulcanized rubber block with a depth of 5 mm, and the vulcanization condition was 148 ° C x 30.
It was vulcanized in minutes to prepare a sample for measuring the adhesive strength. Using this sample, an adhesion test was conducted as follows, and the adhesive strength (kgf / 5mm)
Was evaluated. The results are shown in Table 3. The coated rubber used here is of the following formulation (parts by weight) NR / SBR type. However, in Table 3, represents a non-RF system (excluding RF resin) and represents an RF system (including RF resin).

Content (parts by weight) Non-RF system RF system NR (RSS # 3) 70 70 SBR (Nipol 1502: Zeon Corporation) 30 30 Zinc white 5.0 5.0 Stearic acid 1.0 1.0 Anti-aging agent 6C ^{* 1} 1.5 1.5 Process oil 7.0 7.0 GPF Carbon black 60.0 60.0 Sulfur 2.5 2.5 Accelerator CZ ^{* 2} 1.2 1.2 PVI ^{* 3} 0.5 Penacolite B-18-S ^{* 4} 3.0 Cyletts 964 ^{* 5} 2.0 Note) * 1 N- (1,3-dimethylbutyl) ) -N'-Phenyl-p-phenylenediamine * 2 N-cyclohexylbenzothiazylsulfenamide * 3 N- (cyclohexylthio) phthalimide * 4 Resorcinol resin manufactured by Indospec * 5 American Cyanamid, hexa Methoxymethylated melamine resin Adhesion test method : Adhesion strength (kgf / 5mm) by pulling out the cord embedded in the rubber block according to the adhesion test T-test of JIS L 1017 chemical fiber tire cord test method.
Was evaluated. The results are shown in Table 3.

[0020] As is clear from Table 3, Examples 1 to 1 are compared with Comparative Example 1.
In No. 3, the adhesive strength is improved by the epoxy compound treatment.
It is also understood that the epoxy compound preferably has a large number of functional groups. Cresol novolac is even better.

Comparing Comparative Examples 2 and 3 with Examples 1 and 6, it can be seen that the adhesion decreases when the treatment temperature is out of the range of the present invention. It can be seen that the non-RF coated rubber and the RF coated rubber have higher adhesive strength when the RF coated rubber is used. Strength (strong) in low tension treatment
(kgf)) is decreased (Comparative Example 4).

[0022]

As described above, according to the present invention, P
A predetermined twist is added to the BO fiber or the PBT fiber to form a cord, and the cord is subjected to a predetermined treatment and embedded in rubber, so that the adhesion between the cord and the rubber can be improved. Therefore, according to the present invention, since the PBO fiber and the PBT fiber each have about twice the strength and tensile elasticity of the aramid fiber as described above, it is possible to provide a cord / rubber composite that is lightweight and has excellent durability. Become. This cord / rubber composite is suitable for rubber products such as tires, conveyor belts and hoses.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // B29K 21:00 279: 00 281: 00 (72) Inventor Kazunori Nakakita Hiratsuka City, Kanagawa Prefecture Oiwake 2-1 No. 1 inside Yokohama Rubber Co., Ltd. Hiratsuka Factory (72) Inventor Takayuki Fukutomi No. 2 Oiwake, Hiratsuka City, Kanagawa Inside Yokohama Rubber Co., Ltd. Hiratsuka Factory

Claims (2)

[Claims] 1. A twist coefficient K expressed by K = T√D (where T is the number of twists per 10 cm of cord and D is the total number of denier) of polyparaphenylene benzbisoxazole fiber or polyparaphenylene benzbis thiazole fiber. Is 0 to 25
A cord / rubber composite in which a cord having a twist in the range of 00 is embedded in a rubber matrix through a coat of an epoxy compound and a mixed composition coat of resorcinol / formalin precondensate and rubber latex thereon. body. 2. A twist coefficient K expressed by K = T√D (where T is the number of twists per 10 cm of cord and D is the total number of denier) in polyparaphenylenebenzbisoxazole fiber or polyparaphenylenebenzbisthiazole fiber. Is 0 to 25
The cord is twisted so as to be in the range of 00, the cord is impregnated with an aqueous solution or dispersion of an epoxy compound, and then the cord is heated at a temperature of 160 ° C to 250 ° C,
Then, it is immersed in a mixture of resorcin / formalin initial condensate and rubber latex, heated at a temperature of 160 ° C to 250 ° C, and then the cord thus treated is embedded in rubber to produce a cord / rubber composite. Method.