JPH09210139A - Driving belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize the maximum performance of anti-frying treated codes without lowering fatigue resistance and extension performance of a driving belt. SOLUTION: For the reinforcement fibre code 3 of a cogged belt 1, filament bundled alamide fibers is treated by adhesive in the untwisted or loosely twisted condition, then the bundled fibers are first twisted and then a plurality of twisted bundles are further finally twisted, wherein the final twisted coefficient K is et to 730<K<920, the ratio of first twist coefficient K' with the final twist coefficient K is set to K'/K=1/7-1/5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a transmission belt, and more particularly to measures for strengthening the core wire.

[0002]

2. Description of the Related Art Conventionally, a transmission belt has a reinforcing fiber cord as a core wire embedded in a rubber layer constituting a belt main body along a longitudinal direction of the belt. As the reinforcing fiber cord, an aramid fiber cord having properties of high strength and low elongation is widely known, and as described in, for example, JP-A-54-135954.
An example is a technique of using an aramid fiber cord for the core wire of a toothed belt as a transmission belt.

In recent years, as such an aramid fiber cord, a plurality of raw yarns are aligned and made into a twisted yarn, and a resin treatment and resorcin-formalin-rubber latex (hereinafter,
It has been put into practical use that it is provided with adhesiveness and flexibility by a dipping treatment with a solution (referred to as RFL), and is further overcoated with a rubber paste. It has been reported that the belt using the aramid fiber cord as a reinforcing cord (cord) improves the frayability of the cord and the bending fatigue resistance of the belt. The reason why the frayability of the cord is improved is that the surface of the cord is covered with the RFL layer and the overcoat layer of rubber glue.

However, in the toothed belt using the above aramid fiber cord as a reinforcing cord, when the filament belt of the aramid fiber is rubbed against each other and damaged when running for a long time under high temperature and high load conditions, There is a phenomenon of fraying. Such fluffing of filaments lowers the strength maintenance rate of the toothed belt and promotes bending fatigue. Also, on the belt cut surface, the aramid fiber cord grows from fluff to cord fray, eventually causing pop-out (pulling out), and this pop-out aramid fiber cord bites into the pulley and the belt breaks. There is a risk.

Therefore, means for eliminating the above-mentioned adverse effects and effectively exhibiting the above-mentioned excellent characteristics of the aramid fiber cord, and the excellent characteristics of the aramid fiber cord are advantageously utilized for improving the performance of the belt. Various measures have been proposed (Japanese Patent Laid-Open No. 61-166838).
Japanese Patent Laid-Open No. 1-207480, Japanese Laid-Open Patent Publication No. 4-2.
9644, JP-A-6-57568, etc.).

On the other hand, the toothed belt as the transmission belt is
In order to secure the meshing accuracy, a single twisted yarn having a small elongation is generally used as a cord structure.

[0007]

However, when a single-twisted cord is used as the bundled yarn that has been subjected to the above-described anti-fray treatment, the cord strength is treated because the filament alignment becomes worse. It will be about 20% lower than the case without it.

The present invention has been made in view of the above points, and an object of the present invention is to maximize the strength of the anti-flare treatment cord without impairing the fatigue resistance and elongation performance of the transmission belt. is there.

[0009]

In order to achieve the above object, the present invention provides a pre-treatment and an adhesive treatment at the untwisted or sweet-twisted stage on a bundled yarn, and at the same time, the relationship between the lower twist and the upper twist. It is characterized by devising.

Specifically, the present invention is directed to a transmission belt in which a reinforcing fiber cord made of an aramid fiber is embedded in a rubber layer forming a belt main body along a longitudinal direction of the belt. Was taken.

That is, the solution means of the present invention is, as the reinforcing fiber cord, a pretreatment agent containing an epoxy resin or an isocyanate resin as a main component in a non-twisted or sweet-twisted state on a bundled yarn in which filaments of aramid fiber are bundled. Is further impregnated with the resorcinol-formalin-rubber latex solution. Then, a plurality of twisted bundled yarns subjected to the two-step impregnation treatment are aligned and aligned, and the twisted yarns are twisted in the opposite direction to the above twisted yarn. In this case, the upper twist coefficient K is 730 <K <920.

[Equation 2] And the lower twist coefficient K'is set to 1/7 to 1 of the upper twist coefficient K.
It is characterized in that it is set to / 5.

FIG. 1 shows an example of the power transmission belt of the present invention. In this example, the transmission belt is the toothed belt 1, and the toothed belt 1 will be described below, but the invention is not limited to this.
It can also be applied to other transmission belts such as V-belts and V-ribbed belts.

The toothed belt 1 is provided with a back rubber 2 extending in the belt longitudinal direction, and a reinforcing fiber cord 3 as a core wire is embedded in the back rubber 2 in a spiral shape along the belt longitudinal direction. And a plurality of tooth rubbers 4
Are integrally formed on one surface of the back rubber 2 along the longitudinal direction of the belt at an appropriate pitch, and the belt body 5 is composed of both the rubber layers of the back rubber 2 and the tooth rubber 4. A cover canvas 6 is attached to the surface of the belt main body 5 on the tooth rubber 4 side.

The material of the back rubber 2 and the tooth rubber 4 constituting the belt body 5 is the well-known chlorosulphonated polyethylene rubber (CSM), alkylated chlorosulphonated polyethylene (ACSM), or nitrile rubber (NBR).
80% by weight or more of hydrogenated nitrile rubber (H-NBR) having a double bond portion is used, and a material having improved heat deterioration resistance is used.
-NBR) and a material in which an unsaturated carboxylic acid metal salt is mixed are preferably used. Needless to say, an appropriate material other than the above may be used depending on the belt performance.

The aramid fiber cord which constitutes the reinforcing fiber cord 3 has been treated by the following two steps. As the first step, 0.75-6d
In a non-twisted or sweet-twisted state, for example, an aqueous solution containing an epoxy resin as a main component, a methyl ethyl ketone (MEK) solution, or an isocyanate resin is applied to a bundled yarn (filament group) in which 200 to 2000 filaments of the aramid fiber are bundled. In this step, a toluene solution of a resin as a main component is impregnated, and then heat treatment is performed at about 250 ° C. for 1 to 2 minutes. The subsequent second step is a step of impregnating with the RFL solution and then heat treating at about 250 ° C. for 1 to 2 minutes.

As described above, the pretreatment and RFL treatment are performed in the untwisted or sweet twisted stage before twisting the bundled yarn, in order to bundle the filaments with each other by sufficiently impregnating the treating agent between the filaments. This is to prevent fluffing of the filament and fraying of the cord.

The RFL solution is prepared by mixing an initial condensate of resorcin and formalin with latex, and a high adhesive force can be obtained when the molar ratio of resorcin and formalin is 1: 0.5 to 3. The prepolymer of resorcin and formalin is mixed with latex such that the resin content thereof is 2 to 30 parts by weight with respect to 100 parts by weight of the rubber content of the latex, and the total solid concentration is 5 to 40%.
The concentration is adjusted so that

The above-mentioned latex is a styrene-butadiene-vinylpyridine terpolymer, chlorosulphonated polyethylene (CSM), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), epichlorohydrin, styrene butadiene rubber (SBR). ), Chloroprene rubber (CR), chlorinated butadiene, olefin-vinyl ester copolymers and natural rubber (NR), and other latexes or mixtures thereof.

Furthermore, a plurality of twisted bundled yarns that have been subjected to the impregnation treatment in the above two steps are aligned, and the twisted yarns are twisted in the opposite direction to the twisted yarn, and the twisted coefficient K is 730.
<K <920

(Equation 3) And the lower twist coefficient K'is set to 1/7 to 1 of the upper twist coefficient K.
The following is set to / 5.

That is, when the upper twist coefficient K is less than 730, the aligned state of the bundled yarns is deteriorated and the cord strength cannot be ensured. On the other hand, when the upper twist coefficient K exceeds 920,
This is because the time-dependent elongation of the belt during running becomes large, causing poor meshing, which causes belt damage.

When the lower twisting coefficient K'is less than 1/7 of the upper twisting coefficient K, the filaments are not aligned well and the cord strength cannot be ensured. On the other hand, the lower twisting coefficient K'is the upper twisting coefficient K. If it exceeds ⅕ of the above, the time-dependent elongation of the belt during running becomes large, which causes poor meshing and causes belt damage.

Further, the twisting directions of the lower twist and the upper twist are made opposite to each other in order to secure the shape stability of the reinforcing fiber cord 3.

Further, the reinforcing fiber cord 3 is dipped in rubber paste and subjected to an overcoat treatment. The material of the rubber paste used for this overcoat treatment is a rubber composition having excellent adhesiveness to the back rubber and canvas. For example, chloroprene (C
R), chlorosulphonated polyethylene (CSM), alkylated chlorosulphonated polyethylene (ACSM),
Mainly one or more rubber compositions selected from hydrogenated nitrile rubber (H-NBR) and mixed polymers of hydrogenated nitrile rubber (H-NBR) and unsaturated metal salt of carboxylic acid, and resin therein. It is preferably composed of a solvent-based solution in which components and additives are mixed.

The cover canvas 6 is preferably a woven fabric having elasticity in the longitudinal direction of the toothed belt 1. The woven fabric constituting the woven fabric is an epoxy resin solution, an isocyanate resin solution, an RFL solution, a rubber paste, or the like. It is desirable that the combination of selected ones be processed stepwise. Further, instead of the rubber glue treatment, it is also possible to use coating such as rubber coating or topping. Such fabrics are
After being treated with the adhesive or rubber as described above, it is adhered to the rubber or the reinforcing fiber cords 3 constituting the belt body 5 during belt molding. The cover canvas 6 is preferably made of a material selected from a combination of polyamide fibers, polyester fibers, aromatic polyamide fibers and the like.

With the above construction, in the solution means of the present invention, the filament and the bundled yarn are well aligned due to the twisting relationship between the upper twist and the lower twist, and the cord strength is secured. Moreover, the fatigue performance and elongation performance of the transmission belt are not impaired.

The bundled yarn is subjected to pretreatment and RFL treatment in the untwisted or sweet twisted stage before twisting, whereby the treating agent is sufficiently impregnated between the filaments and the filaments are bound together. No filament fluffing or cord fraying.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, specific examples of the present invention will be described in detail.

(Example 1) 1500d raw yarn (trade name Kevlar) made of filament group (bundle yarn) of aramid fiber
119-made by DuPont) is mixed with epoxy resin (trade name Denacol EX521-made by Nagase Kasei Kogyo Co., Ltd.) with a small amount of liquid rubber and a crosslinking agent to produce methyl ethyl ketone (ME).
It was immersed in a pretreatment liquid having a concentration of 15% by weight dissolved in K).

An aramid fiber cord material was prepared by pulling up and heat-treating at 250 ° C. for 1 minute so that the solid content mainly composed of epoxy resin adhered to the filament.

Next, NBR latex (trade name Nip
1562 to Zeon Co., Ltd.) was used to prepare an RFL solution having a concentration of 30% by weight, and the aramid fiber cord material was immersed in this RFL solution and then heat-treated at 250 ° C. for 1 minute.

Then, the treated aramid fiber cord material treated as described above is twisted in one direction with a twist coefficient K '= 115.
Twist the lower part with, and arrange three of them to make a twist coefficient K = 800
After being twisted with the above, it was immersed in a 20% by weight solution of a rubber paste containing chlorosulfonated polyethylene as a main component.

After withdrawing, the rubber layer was coated by drying at 100 ° C. for 1 minute. An aramid fiber cord is manufactured through each of the above processes and processings.

Then, as shown in FIG. 1, the toothed belt 1 which is an example of the power transmission belt of Example 1 is manufactured by using the aramid fiber cord 3 obtained as described above as a core wire. . As the cover canvas 6, 6,6 nylon yarn is used for the yarn extending in the belt width direction, and industrial 6,6 nylon woolie processing is used for the yarn extending in the belt longitudinal direction. As the back rubber 2 and the tooth rubber 4, a rubber composition containing hydrogenated nitrile rubber as a main raw material is used.

The toothed belt 1 is manufactured by the ordinary press-fitting method using the above materials, is an STS tooth mold having a tooth pitch of 8 mm, has 113 teeth and a belt width of 19 mm.

(Examples 2 to 5, Comparative Examples 1 to 6) As the aramid fiber cord, the same treatment as in Example 1 was applied,
In addition, Table 1 shows the cord configuration, upper twist coefficient, and lower twist.
The one as shown in was used. Then, a toothed belt of each example similar to that of Example 1 was manufactured.

The toothed belts of Examples 1 to 5 and Comparative Examples 1 to 6 described above were mounted on a bending running tester as shown in FIG. 2 and run for 700 hours. Then, the elongation rate of each test belt before and after running was evaluated, and the belt initial strength and the belt strength ratio were measured, and the results are shown in Table 1.

In FIG. 2, 1 is a toothed belt and 7 is a toothed belt.
Is a drive pulley, 8 is an idler pulley, 9 is a tension pulley, 10 is a load, 11 is a fulcrum, and the circumference of the toothed belt 1 during the test is 904 mm and the drive pulley 7
The number of rotations is 5500 rpm.

[0038]

[Table 1]

As is clear from the data in Table 1, in Examples 1 to 5, good results were obtained in all three evaluation items, but Comparative Examples 1 and 5 in which no undertwist was applied,
The ratio of the lower twist coefficient K'and the upper twist coefficient K is K '/ K = 1 /
Comparative Examples 2, 3 and 6 not within the range of 7 to 1/5 and Comparative Example 4 in which the twisting coefficient K was less than 730 were poor in any of the three evaluation items.

[0040]

As described above, according to the present invention,
As a reinforcing fiber cord for a power transmission belt, an adhesive treatment is applied to a filament-converging yarn of aramid fiber in a non-twisted or sweet-twisted state, and a plurality of the twisted yarns of this concatenated yarn are aligned and ply-twisted. At this time, the twisting coefficient K is 730 <K
Since it was set to <920 and the ratio of the lower twist coefficient K'to the upper twist coefficient K was set to K '/ K = 1/7 to 1/5, the filament and the bundled yarns are arranged in an orderly manner to secure the cord strength. Therefore, the fatigue resistance and elongation performance of the transmission belt can be secured.

[Brief description of drawings]

FIG. 1 is a perspective view of a toothed belt.

FIG. 2 is an explanatory diagram of a bending running test.

[Explanation of symbols]

 1 Belt with teeth (transmission belt) 3 Fiber cord for reinforcement 5 Belt body

Claims (1)

[Claims] 1. A transmission belt in which a reinforcing fiber cord made of aramid fiber is embedded in a rubber layer constituting a belt main body along a belt longitudinal direction, wherein the reinforcing fiber cord bundles filaments of aramid fiber. The bundled yarn is impregnated with a pretreatment agent containing an epoxy resin or an isocyanate resin as a main component in a non-twisted or sweet twisted state, and further impregnated with a resorcin-formalin-rubber latex solution. A plurality of twisted bundled yarns are aligned and twisted in the opposite direction to the above twist, and the twisting coefficient K is 730 <K <920. And the lower twist coefficient K'is set to 1/7 to 1/5 of the upper twist coefficient K.