JP2003055882A - Twisted cord for reinforcing rubber having improved setting property and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a torque of running back of twists in a twisted cord comprising nonthermoplastic fibers. SOLUTION: This twisted cord for reinforcing rubber comprises a multifilament yarn of the nonthermoplastic fibers and is characterized by applying a latex to the twisted cord.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention can reduce the untwisting torque of a twist cord of a non-thermoplastic fiber and improve the workability when the twist cord of a non-thermoplastic fiber is used for rubber reinforcement. The present invention relates to a twisted cord for rubber reinforcement and a method for manufacturing the same.

[0002]

2. Description of the Related Art When a fiber composed of multifilaments is used as a reinforcing material, it is used as a cord by twisting the fiber for the purpose of improving the tying property of the fiber and the fatigue property of the fiber. There is a case. In particular, when used as a reinforcing fiber for a rubber belt, a rubber hose, etc., the fatigue property of the fiber is important, and therefore the fiber is often twisted and used as a cord. However, in the twisted cord, a twist back torque is generated which tends to rotate in the direction opposite to the twisted direction. The untwisting torque may cause so-called snare, in which the cords are wound around each other when the twisted cord is released from the bobbin or the like to have a low tension. Not only does the snarl enter the product as it is and make it a defective product, but it also causes the yarn path guide from the snarl generation part to the product to be clogged, causing damage to the guide or cutting the cord due to abnormal tension. was there. That is, if snare occurs in the cord during the process, the quality and productivity of the product using the cord will be significantly reduced.

In order to solve such a problem, two or more single-twisted cords, which are twisted in the same direction, are aligned and arranged.
The twisted cord is twisted in the direction opposite to the twisting direction of the single twisted cord to form a twisted cord, and the twisting back torque of the single twisted cord is reduced. In addition, in the case of thermoplastic fibers, twisting setting processing is generally performed to keep the twisted cord at a temperature above the glass transition point to heat set the twisted cord and reduce the twisting torque of the twisted cord. ing. Similarly, for cellulosic fibers such as cotton, a twist prevention set is also performed with high temperature steam.

[0004]

However, in the case of a ply-twisted cord in which two or more single-twisted cords are aligned and twisted, fatigue properties and high elongation of a single-twisted cord made of a single cord are obtained. In some cases, the physical properties differ from the properties, and the required code properties cannot be obtained. In addition, since the twisting process is performed in two stages, there is a drawback that the twisting process is increased and the processing cost required for twisting is higher than that of the single twist cord. Furthermore, it is necessary to start from a twisted yarn having a fineness less than half the required fineness of the cord, and it is unavoidable that productivity is deteriorated.

The method of reducing the untwisting torque by heat setting the twisted cord is an effective method when the cord is a thermoplastic fiber. However, in the case of a non-thermoplastic fiber, it is difficult to obtain the anti-twist effect, and it cannot be said that this is an effective method for obtaining the anti-twist effect. In addition, the anti-twisting process with a high temperature steam set has a greater anti-twisting effect than heat alone, but it often adversely affects the physical properties of the cord such as the strength and elongation of the twisted cord, and is aimed at rubber reinforcement. In some cases, it is not suitable as a method for setting a twist cord made of high-strength fiber.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art. To reduce the untwisting torque of a twisted cord made of non-thermoplastic fiber by means of a latex film, the subsequent processability is improved. It is an object of the present invention to provide a twisted cord for rubber reinforcement capable of improving the rubber composition and a manufacturing method thereof.

[0007]

In order to achieve the above object, the present invention adopts the following configurations. That is, (1) a twisted cord for rubber reinforcement, comprising a twisted cord for rubber reinforcement made of multifilament of non-thermoplastic fiber, wherein latex is attached to the twisted cord.

(2) The twisted cord for rubber reinforcement as described in (1) above, wherein the non-thermoplastic fiber is an aromatic polyamide fiber.

(3) The twisted cord for rubber reinforcement as described in (1) or (2) above, wherein the amount of latex attached to the twisted cord is 2.0% by weight or less.

(4) The twisted cord for rubber reinforcement according to any one of the above (1) to (3), characterized in that the inorganic fine powder is added to the latex.

(5) A rubber-reinforcing twisted cord, characterized in that a rubber-reinforcing twisted cord composed of multifilaments of non-thermoplastic fibers is impregnated with a latex solution, and then the liquid phase is evaporated to solidify the latex. Production method.

(6) The method for producing a twisted cord for rubber reinforcement as described in (5) above, wherein fine powder of an inorganic substance is added to the twisted cord after the latex is substantially solidified.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention impregnates a latex solution with a twisted cord of a non-thermoplastic fiber which is a rubber-reinforcing fiber such as a rubber belt and a rubber hose, and then dries it to evaporate a liquid layer to solidify the latex. Then, a latex film is formed to reduce the untwisting torque of the twisted cord. Further, the tackiness caused by the latex film is reduced by adding fine powder of an inorganic substance.

The present invention will be described in detail below.

The non-thermoplastic fiber of the present invention is a fiber that does not soften and melt even at high temperatures. In the present invention, the type of fiber is not particularly limited, but aromatic polyamide fibers widely used in the field of rubber reinforcement are preferred. Further, also in the case of polyparaphenylene benzbisoxazole (PBO) fiber, which is a fiber having high strength and high elastic modulus similar to the aromatic polyamide fiber, the cord according to the method for reducing the untwisting torque of the present invention is effective.

The fiber used for rubber reinforcement is generally twisted and used as a cord to improve fatigue resistance. By being twisted, each monofilament in the cord becomes likewise twisted, and each monofilament tends to rotate in the direction to release this twist. This untwisting torque that tends to rotate increases as the number of twists increases. On the other hand, in order to improve fatigue resistance, it is generally advantageous to increase the number of twists, and the twisting torque may be increased. A single-twisted cord is generally used as the twisted cord with reduced twist-back torque of the present invention, but even with a twisted cord, for example, when the number of twists in the lower twist and the number of twists in the upper twist are significantly different, the twist-back torque May be a problem, and in such a case, the processing code of the present invention is effective. Further, or when the lower twist and the upper twist have the same twist direction, the treated cord of the present invention is also effective.

The untwisting torque is reduced by the latex film, but its effect can be increased by increasing the amount of latex attached to the twisted cord.
However, increasing the amount of latex attached increases the adhesiveness of the twisted cords, which causes the twisted cords to stick to each other, resulting in poor release from the bobbin and abnormal tension in the yarn guide. As a result, practical problems arise. The amount of latex attached is preferably 2.0%
It is less than or equal to the weight, more preferably 0.2 to 1.2% by weight.

The latex used in the present invention may be of any kind, but it is preferable to use the same kind of latex as the matrix rubber. Latex of the same type as rubber used for rubber belts, rubber hoses, etc. is NBR (acrylonitrile / butadiene rubber) latex, CR (chloroprene rubber) latex, SBR (styrene / butadiene rubber) latex, BR (butadiene rubber) latex, IR (Isoprene rubber) Latex, etc.

To the twisted cord impregnated and solidified with the latex of the present invention, fine powder of an inorganic substance can be added after the latex is substantially solidified. As a method for adding the fine powder of the inorganic substance, a solution in which the fine powder is dispersed is prepared, and a twisted cord treated with latex is passed through the solution, or a roller installed so as to come into contact with and rotate the solution. There is a method of adding the inorganic fine powder to the twisted cord that has been subjected to the latex treatment. Twisted cord with inorganic fine powder added improves the adhesion between cords, and
It is also possible to prevent the occurrence of abnormal tension during contact with the yarn guide or the like during the process, and improve the process passability.

The type of inorganic material is not particularly limited, but silica fine powder is suitable as the inorganic fine powder. If the amount of addition is large, the effect of improving the tackiness of the latex will be high, but since it will drop off in the yarn guide and the like, it is preferably about 0.2 to 1.0% by weight.

The non-thermoplastic fiber twisted cord of the present invention, which has a reduced untwisting torque, remarkably improves the passability in the subsequent processing steps and improves the product quality and productivity of the fiber-reinforced rubber processed product. Has the effect of improving.

[0022]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Multifilament yarn of para-aromatic polyamide fiber,
A single twist (S twist) was applied 20 times per 10 cm to a fineness of 1670 dtex and the number of single yarns was 1000, and the bobbin was wound. Then, the twisted cord was supplied from the bobbin to the cord dipping machine, passed through the latex solution in the dipping bath installed in the cord dipping machine, and then passed through the dryer set at 180 ° C for 90 seconds to solidify the latex. Then I wound it up on a bobbin. The latex was attached to almost the surface layer of the cord, and the amount of the latex attached to the cord was 1.0% by weight. In order to confirm the effect of the present invention, the cord is passed through a paper clip with a load of about 10 grams, and the cord is pulled out from the bobbin while holding one end of the cord with one hand.
The other hand grasped the pulled-out length of 1 meter. Then, both hands holding the cord were brought close to each other, and the two cords were juxtaposed while the position of the paper clip was set to the central part, and the cord stopped about 6 turns in the Z twisting direction.

Example 2 In Example 1, the latex was solidified in a drier and then passed through an aqueous solution in which fine silica powder was dispersed. Then, it was passed through a dryer at 180 ° C. for 90 seconds to remove water, and wound on a bobbin. The obtained cord had silica adhered to its surface, the cords were not fixed to each other by latex, and the tension did not fluctuate due to adhesion even when pulled out from the bobbin.

Comparative Example 1 In Example 1, the same process was carried out without impregnating the latex, and the product was wound on a bobbin. Then, the cord was pulled out from the bobbin by the same procedure as in Example 1, and the number of rotations of the cord was counted by bringing both gripped hands close to each other. As a result, the cord stopped about 43 turns in the Z direction.

Comparative Example 2 In Example 1, the amount of latex adhered was 2.5% and the latex was wound on a bobbin. Even when the obtained cord was unwound from the bobbin, the cords adhered to each other, and the fluctuation of the release tension from the bobbin was large.

[0027]

INDUSTRIAL APPLICABILITY In the present invention, the twisting torque of the twisted cord made of non-thermoplastic fibers can be reduced, and the production of a rubber-reinforced product using this cord can be facilitated.

Claims (6)

[Claims] 1. A twisted cord for rubber reinforcement comprising a multifilament of non-thermoplastic fibers, wherein a latex is adhered to the twisted cord. 2. The twisted cord for rubber reinforcement according to claim 1, wherein the non-thermoplastic fiber is an aromatic polyamide fiber. 3. The twisted cord for rubber reinforcement according to claim 1, wherein the amount of the latex attached to the twisted cord is 2.0% by weight or less. 4. The twisted cord for rubber reinforcement according to claim 1, wherein fine powder of an inorganic substance is added to the latex. 5. A rubber-reinforced twisted cord comprising a non-thermoplastic multifilament twisted cord for rubber reinforcement impregnated with a latex solution and then evaporating a liquid phase to solidify the latex. Method. 6. The method for producing a twisted cord for rubber reinforcement according to claim 5, wherein fine powder of an inorganic substance is added to the twisted cord after the latex is substantially solidified.