JPH08121541A - Motive power transmitting belt - Google Patents

Abstract

PURPOSE: To reduce elongation at belt traveling time, maintain high tensile force, and improve motive power transmitting efficiency by using an object by performing adhering drawing fixing treatment on a polyester cord having specific characteristics before the adhering drawing fixing treatment is performed, as tension members. CONSTITUTION: A V belt 1 is a belt of a type in which rubber cloth 2 woven by natural fiber or synthetic fiber yarn exists only on upper and lower surfaces of the belt 1, and tension members 3 are embedded in an adhesive rubber layer 4 adjacent to a compression rubber layer 5, and short fibers 6 are mixed in the belt width direction in the compression rubber layer 5. These tension members are a polyester cord by vertically intertwisting a polyester multifilament, and an adhesive is applied to this cord, and drawing heat fixing treatment is performed at a high temperature. The polyester cord having characteristics that an initial tensile resistance degree is not less than 100g/de and a hot-air shrinkage factor is not more than 2.5% and hot-air time contraction stress is not more than 0.15g/de before this treatment is performed, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission belt, and more particularly to a friction transmission belt such as a V-belt, a V-ribbed belt, a flat belt, etc., in which elongation during belt running is reduced and high belt tension is maintained. , Concerning measures to increase power transmission efficiency.

[0002]

2. Description of the Related Art Generally, belts such as flat belts, V-belts, V-ribbed belts, etc., which are wound and transmitted, transmit power by frictional force of the belt, and therefore, the belt during traveling has a constant tension according to driving conditions. Need. If the tension of the belt during traveling is reduced, the grip force with the pulley is reduced, and slippage easily occurs and power cannot be transmitted sufficiently. Such a decrease in belt tension is strongly affected by the stress relaxation characteristics of the tensile body and the thermal contraction caused by the friction between the belt and the pulley during running. The tensile member responsible for belt performance is a cord obtained by twisting several multifilaments undertwisted and collecting several multifilaments and twisting them up.Adhesive with the rubber layer, high elasticity, small stress relaxation, and high thermal stress A stretching heat setting treatment is carried out in order to impart The stretched heat-setting treated cord is given high elasticity, high strength and high heat shrinkage stress, and then disposed and integrated with a constant tension in the rubber layer and vulcanized.

Up to now, the polyester cord taken out from the belt in order to improve the transmission ability of the V-belt has an initial tensile resistance of 58 g / de or more and a thermal stress of 0.5 g / de when heated at 150 ° C. for 8 minutes. A power transmission belt having the above characteristics and a stress ratio of 0.928 or more is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-255637.

Further, several bundles of high-toughness polyester multifilaments are twisted up and down, a polyester cord is applied with an adhesive, and stretch heat-fixing treatment is performed to obtain a toughness of 8.5 g / de · √% or more, 1.52 g / de. Elongation under load of 2.2% or less, dry heat shrinkage at 150 ° C of 3.5% or less, dry heat shrinkage at 150 ° C of 0.2
A tension member for a power transmission belt having a characteristic of 0 g / de or more and a transmission belt using the same are disclosed in Japanese Patent Publication No. 5-20991.
No.

Further, recently, the ratio of the dry heat shrinkage ratio before the adhesive stretching heat setting treatment and the dry heat shrinkage stress is 12.0% / g.
A power transmission belt using a polyester cord having a characteristic of / de or less as a tensile body is disclosed in JP-A-3-163.
No. 241 is disclosed.

[0006]

By the way, in order to maintain the belt tension required for the belt performance, it is desirable that the stress relaxation of the cord is small and the thermal stress of the cord is large, and it also affects the elongation of the belt. It is also necessary that the cord has a high initial tensile resistance, and further, it is desired that the dry heat shrinkage rate of the cord is low for the dimensional stability of the belt over time. However, in the conventional polyester fiber cord, after the drawing heat setting treatment, the dry heat shrinkage tends to increase as the heat stress increases, and the high heat stress is sufficiently satisfied while maintaining the low dry heat shrinkage. It was not possible to obtain a stretch heat setting treatment cord.

The present invention has been made in view of this point, and an object of the present invention is to specify the characteristics of a tensile member so that the elongation of the power transmission belt during belt running is small, To maintain high tension and increase power transmission efficiency.

[0008]

In order to achieve the above object, in the present invention, the properties of the tensile body are specified as described below.

According to the first aspect of the present invention, the initial tensile resistance is 100 g / de before the adhesive stretching heat setting treatment.
Above, dry heat shrinkage of 2.5% or less, dry heat shrinkage stress 0.1
A power transmission belt using a polyester cord having a characteristic of 5 g / de or less, which is subjected to an adhesive stretch heat setting treatment as a tensile body.

According to a second aspect of the present invention, in the power transmission belt, the polyester fibers are twisted together, subjected to an adhesive treatment and a stretch heat setting treatment, and have a breaking strength of 6 g / de.
Above, elongation at load of 2 g / de is 2.0% or less, initial tensile resistance is at least 140 g / de, dry heat shrinkage ratio at 150 ° C is 3.5% or less, shrinkage stress at dry heat at 150 ° C is 0.
A polyester cord having characteristics of 50 g / de or more and a stress relaxation rate at 60 ° C. of 15% or less was used as a tensile body.

According to a third aspect of the present invention, in the power transmission belt, the polyester fibers are twisted together and subjected to an adhesive treatment and a stretch heat-fixing treatment. The shrinkage ratio is 6 or less, the stress ratio is 25 or less, and the diminutive value is 5 or less. A polyester cord having a stress relaxation ratio of 5 or less was used as a tensile body.

According to a fourth aspect of the present invention, a tensile strength member made of polyester cord in a belt has a breaking strength of 6 g / de or more, an elongation at load of 2 g / de or less of 1.5% and an initial tensile resistance of 130 g / de. As described above, the dry heat shrinkage ratio at 150 ° C is 3.0% or less, and the dry heat shrinkage stress at 150 ° C is 0.4.
The characteristic value was 0 g / de or more and the stress relaxation rate at 60 ° C. was 18% or less.

According to a fifth aspect of the present invention, the tensile member made of polyester cord in the belt has characteristics of a shrinkage ratio of 7 or less, a stress ratio of 40 or less, a diminutive value of 5 or less, and a stress relaxation ratio of 7 or less. .

[0014]

The characteristic values of the polyester cord in each of the above-mentioned states will be described. First, since the tension on the tension side of the belt becomes large in order for the transmission belt to transmit a high load, the initial tension of the tensile body that bears the tension of the transmission belt. A belt having a high transmission force cannot be expected unless the tensile resistance is 100 g / de or more for the unbonded stretch heat-set cord, 140 g / de or more for the adhesive stretch heat-set cord, and 130 g / de or more for the belt cord. . Further, for the high load transmission, the breaking strength in the adhesive stretch heat setting treatment cord and the cord in the belt needs to be 6 g / de or more. 2 g / de
The elongation under load has an effect on the belt elongation from the attachment of the belt to the running, that is, the transmission force, and has the characteristics of 2.0% or less for the adhesive stretch heat setting treatment cord and 1.5% or less for the cord in the belt. Without it, a belt with high transmission cannot be expected.
As such a highly elastic cord, a high shrinkage stress during dry heat can be expected, and this shrinkage stress during dry heat is generated by the heat when the belt runs, so that the pulley is tightened, the belt tension is maintained, and the transmission capacity is improved. Higher is desirable, 150 ℃
In dry heat, the shrinkage stress is 0.15 g / de or less for the unbonded stretch heat set treatment cord, 0.50 g / de or more for the adhesive stretch heat set treatment cord, and 0.40 g / de for the belt cord.
De or more is desirable. As a means for suppressing the decrease in belt tension, it is desirable to reduce the stress ratio and the stress relaxation rate. The stress relaxation rate at 60 ° C. in the adhesive stretch heat setting treatment cord is 15% or less, the stress ratio is 25 or less, and the stress relaxation ratio is The stress relaxation rate at 60 ° C. in the cord in the belt is preferably 18% or less, the stress ratio is 40 or less, and the stress relaxation ratio is 7 or less.

However, a cord exhibiting high elasticity, high dry heat shrinkage stress, and low stress relaxation rate has a large dimensional change over time, and a transmission belt having good dimensional stability cannot be obtained, and the quality of the belt product is high. Is significantly reduced.

In order to keep the dimensional change with time small, the dry heat shrinkage at 150 ° C. is 2.5% or less for the unbonded stretch heat setting treatment cord and 3.5% or less for the adhesive stretching heat setting treatment cord. The cord in the belt is preferably 3.0% or less.

The above-mentioned values are set such that the shrinkage ratio for the adhesive stretch heat-setting cord is 6 or less and the shrinkage value is 5 or less, and the shrinkage ratio for the cord in the belt is 7 or less and the shrinkage value is Is preferably set to 5 or less.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a vertical cross-sectional view of a V-belt 1 as a transmission belt according to this example, in which the V-belt 1 has a rubber-coated cloth 2 woven of natural fiber or synthetic fiber thread only on the upper and lower surfaces of the belt. It is the type of belt that exists. The tensile body 3, which is a feature of this example, is embedded in the adhesive rubber layer 4 adjacent to the compression rubber layer 5. Short fibers 6 are mixed in the compressed rubber layer 5 in the belt width direction. The present invention is not limited to the V-belt of the above-mentioned type, and a wrapped V-belt in which the rubber-coated cloth 2 covers the entire circumference of the belt may be used, and as shown in FIG. Therefore, a V-ribbed belt 8 having a plurality of ribs 7 in the belt longitudinal direction may be used. The tensile member 3 used for the above-mentioned various types of belts is a polyester cord in which polyester multifilaments are twisted up and down, and an adhesive is applied to the cord and stretch heat setting treatment is performed at high temperature. Specifically, the polyester cord is obtained by twisting a polyethylene terephthalate filament yarn of 1000 denier into a total denier 6000 by upper twisting and lower twisting, and regarding the treatment, a usual adhesion treatment, for example, a first bath containing an epoxy adhesive or an isocyanate adhesive. Then, the adhesive is applied by sequentially immersing it in a second bath consisting of RFL and RFL, and stretching heat setting treatment is performed at high temperature. The adhesive is not limited to this, and other known adhesives may be used.

The characteristics of the unbonded stretch heat set polyester cord used are shown in Table 1 (see Code 1 and Code 2 in Table 1). The polyester cord has an intrinsic viscosity of 0.45 to 0.95 and a constitution of 1000 de / 2 × 3.
Is.

[0020]

[Table 1] Next, the adhesive treatment of the cord and the hot drawing conditions under high temperature will be described.

After impregnating the tank containing the isocyanate adhesive and pre-dip, it is first dried by passing it through a drying oven set at a temperature of 245 ° C. for 60 seconds with a relatively high tension of 0.5 g / de. Then, it was immersed in a tank containing an adhesive consisting of a resorcin-formalin-latex (RFL) solution, and was 245 at a tension of 1.6 to 2.2 g / de.
It is passed through a stretching heat-setting processor set at a temperature of ° C for 60 seconds to obtain a treatment cord.

Next, using the above cord, a V-ribbed belt as shown in FIG. 2 was produced by a known method.

The V-ribbed belt thus obtained was subjected to static and dynamic evaluations. This static evaluation method,
The dynamic evaluation method and its results are shown below.

(1) Static Evaluation of Adhesion Stretching and Heat-fixing Cord and Cord in Belt Static evaluation method of the characteristic value of the tension member for belt is as follows.

(A) Breaking strength, elongation at 2 g / de load,
The initial tensile resistance is JIS L-1017 (1983).
According to the year).

(B) The dry heat shrinkage ratio is JIS L-1017.
(1983), it was determined by leaving it for 30 minutes under an ambient temperature of 150 ° C.

(C) Shrinkage stress during dry heat is JIS L-10
17 (1983), and left for 3 minutes at 150 ° C. ambient temperature to obtain the value.

(D) As for the stress relaxation rate, as shown in FIG. 3, after an initial set load of 1 g / de (F ₀ ) was applied, it was allowed to stand for 5 minutes and then 5
Min after the value (Fig midpoint A) and _{F t, (F 0 -F t} ) / F
_The measurement was carried out under the atmosphere temperature of 60 ° C. indicated by ₀ × 100.

(E) Shrinkage ratio is the ratio of dry heat shrinkage to dry heat shrinkage stress.

(F) The stress ratio is the ratio between the stress relaxation rate and the shrinkage stress during dry heat.

(G) The low value is the sum of the elongation at 2 g / de load and the dry heat shrinkage.

(H) The stress relaxation ratio is the ratio between the stress relaxation rate and the dry heat shrinkage rate.

Regarding the characteristic values of the cords thus obtained, the characteristic values of the cords after the adhesive stretching heat setting treatment are shown in Table 2.
The characteristic values of the cords taken out from the V-ribbed belt are shown in Table 1 (see Code 1 and Code 2), and in Table 3 (see Code 1 and Code 2 in Table 3). The comparative codes 1, 2, and 3 in each table are characteristic values of conventional polyester codes generally used as a tensile member.

[0034]

[Table 2]

[Table 3] (2) Belt tension reduction test As shown in FIG. 4, the belt 8 is installed on the pulleys 9 and 10 having a diameter of 100 mm, the initial attachment tension is 900 N, and the number of revolutions of the pulley during running is 3600 r.s.r. p. m. As a result, the test was conducted under three temperature conditions of 40 ° C., 70 ° C. and 100 ° C. Then, as shown in FIG. p. m. Run for 1.5 hours
After s, the belt is stopped and then allowed to cool to 24 hours, and the belt tension is measured.

The measured results, that is, the belt tension lowering characteristics are shown in Table 4, FIG. 6, FIG. 7 and FIG.

[0036]

[Table 4] The belt tension retention rate depends on the initial tensile resistance and stress relaxation rate of the cord up to around 70 ° C., that is, the initial tensile resistance is low, the stress relaxation rate of 60 ° C., and the comparative cords 1 and 2 having a large stress ratio. The belt tension maintenance ratio of 3 is low.

Further, in the region above 70 ° C. at which the cord shrinkage due to heat begins to appear, it depends on the stress relaxation ratio which is the ratio of the stress relaxation rate of the cord after the adhesive stretching heat setting treatment and the dry heat shrinkage. Therefore, at the atmospheric temperature of 100 ° C., the belt tension maintenance ratios of the comparative cords 1 and 3 having a large stress relaxation ratio are low. On the other hand, in the case of the comparative code 2, the area in which the code contraction due to heat appears, that is, the ambient temperature of 100 °
Under the conditions, the belt tension maintenance rate is comparative code 1 and 3.
However, the dimensional stability is inferior because of a large decrease in the elongation at 2 g / de load and dry heat shrinkage.

In contrast to each of these comparative cords, the cords 1 and 2 according to the present example show a high belt tension maintenance rate at any ambient temperature and a low marginal value. That is, as the characteristic value of the cord having the characteristics as shown in Table 3, that is, the polyester cord taken out from the belt, the breaking strength is 6 g / de or more, the elongation at load of 2 g / de is 1.5% or less, and the initial tensile strength is Resistance of 130 g / de or more, dry heat shrinkage at 150 ° C of 3.0% or less, 150
Shrinkage stress during dry heat at ℃ 0.40g / de or more, 60
A power transmission belt having a tensile strength of 18% or less, or a shrinkage ratio of 7% or less, a contraction ratio of 40 or less, a stress ratio of 5 or less, and a stress relaxation ratio of 7 or less is used as a belt running belt. It can be seen that the elongation inside is small and the high tension is maintained.

In order to obtain a cord having such a characteristic value, the characteristic value before the adhesive stretching heat setting treatment is shown in Table 1, that is, the initial tensile resistance is 100 g /
It is necessary to have a property of not less than de, not more than 2.5% of dry heat shrinkage, and not more than 0.15 g / de of shrinkage stress at dry heat. The characteristic values are shown in Table 2, that is, breaking strength of 6 g / de or more, elongation at load of 2 g / de of 2.0% or less, initial tensile resistance of 140 g / de or more, and dry heat shrinkage ratio at 150 ° C. of 3. 5% or less, 150 ° C dry heat shrinkage stress of 0.50 g / de or more, 60 ° C stress relaxation rate of 15% or less, or shrinkage ratio of 6 or less, stress ratio of 25 or less, diminutive value of 5 or less, stress relaxation ratio. Those having a characteristic of 5 or less are required.

(3) Belt Dimension Change The difference between the outer circumference immediately after vulcanization and the outer circumference after 30 days was divided by the outer circumference immediately after vulcanization. The results are shown in Table 5.

[0041]

[Table 5] As shown in Table 5, the cords 1 and 2 according to the present example are superior in dimensional stability because it can be seen that the change with time is smaller than that of each comparative cord.

As described above, by using the polyester cord of this embodiment, it is possible to obtain a stretch heat-setting treated cord which sufficiently satisfies high thermal stress while maintaining a low dry heat shrinkage ratio for the power transmission belt. And with this,
Elongation during belt running is small, high tension is maintained, and power transmission efficiency can be improved.

[0043]

The effects of the present invention will be described below.
In the invention according to claim 1, as the unbonded stretch heat setting treatment cord, characteristics such as an initial tensile resistance of 100 g / de or more, a dry heat shrinkage ratio of 2.5% or less, and a dry heat shrinkage stress of 0.15 g / de or less are used. Since the polyester cords used are used for the power transmission belt after being subjected to the adhesive stretching / fixing treatment, the high power transmission efficiency of the load, the dimensional stability are excellent, and the reduction of the belt tension is small.

According to the second aspect of the invention, the breaking strength is 6 g / de or more and 2 g / d or more by applying the stretching heat-setting treatment.
e Elongation under load 2.0% or less, initial tensile resistance 140g
/ De or more, dry heat shrinkage at 150 ° C of 3.5% or less, dry heat shrinkage stress at 150 ° C of 0.50 g / de
As described above, a polyester cord having a stress relaxation rate of 15% or less at 60 ° C. is used as a belt tension member,
Further, in the invention according to claim 3, since the polyester cord having the shrinkage ratio of 6 or less, the stress ratio of 25 or less, the diminutive value of 5 or less, and the stress relaxation ratio of 5 or less is used as the tensile member of the belt. It has the advantages of high load power transmission efficiency, dimensional stability, and small belt tension drop.

In the invention according to claim 4, the polyester cord as a tensile member in the belt has a breaking strength of 6 g /
de or more, 2 g / de load elongation 1.5% or less, initial tensile resistance 130 g / de or more, 150 ° C dry heat shrinkage 3.0% or less, 150 ° C dry heat shrinkage stress 0.40 g / Stress relaxation rate of 18 at 60 ° C or higher than de
% Or less, and in the invention according to claim 5, the polyester cord has characteristics such as a shrinkage ratio of 7 or less, a stress ratio of 40 or less, a diminutive value of 5 or less, and a stress relaxation ratio of 7 or less. Since this is also used, high load power transmission efficiency, dimensional stability are excellent, and a decrease in belt tension is small.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a V-belt using a tensile body according to the present invention.

FIG. 2 is a cross-sectional view of a V-ribbed belt using a tensile body according to the present invention.

FIG. 3 is a diagram showing a relationship between a load and time in measuring a stress relaxation rate.

FIG. 4 is a diagram showing a testing machine in a belt tension reduction test.

FIG. 5 is a diagram showing test conditions in a belt tension reduction test.

FIG. 6 is a diagram showing the results of a belt tension reduction test in a 40 ° C. atmosphere.

FIG. 7 is a diagram showing the results of a belt tension reduction test in a 70 ° C. atmosphere.

FIG. 8 is a diagram showing the results of a belt tension reduction test in a 100 ° C. atmosphere.

[Explanation of symbols]

 1 V-belt 3 Tensile body 8 V-ribbed belt

Claims (5)

[Claims] 1. Before the adhesive stretching heat setting treatment,
Initial tensile resistance of 100 g / de or more, dry heat shrinkage 2.
A power transmission belt comprising a polyester cord having a characteristic of 5% or less and a shrinkage stress at dry heat of 0.15 g / de or less, which is subjected to an adhesive stretch heat setting treatment as a tensile body. 2. A polyester fiber is twisted together, subjected to an adhesive treatment and a stretch heat setting treatment, and has a breaking strength of 6 g.
/ De or more, 2 g / de elongation at load 2.0% or less, initial tensile resistance 140 g / de or more, dry heat shrinkage ratio at 150 ° C 3.5% or less, dry heat shrinkage stress at 150 ° C 0.50 g / De or more, stress relaxation rate at 60 ° C 1
A power transmission belt comprising a polyester cord having a characteristic of 5% or less as a tensile member. 3. A polyester cord which is formed by twisting polyester fibers and is subjected to an adhesive treatment and a stretching heat-setting treatment, and has a shrinkage ratio of 6 or less, a stress ratio of 25 or less, a diminutive value of 5 or less, and a stress relaxation ratio of 5 or less. A power transmission belt characterized by using as a tensile body. 4. A tensile member comprising a polyester cord in a belt has a breaking strength of 6 g / de or more, an elongation at load of 2 g / de of 1.5% or less, an initial tensile resistance of 130 g / de or more, and a dryness at 150 ° C. Heat shrinkage of 3.0% or less, 150
Shrinkage stress during dry heat at ℃ 0.40g / de or more, 60
A power transmission belt having a characteristic value of a stress relaxation rate of 18% or less at ° C. 5. A power source characterized in that a tensile member made of a polyester cord in a belt has a shrinkage ratio of 7 or less, a stress ratio of 40 or less, a diminutive value of 5 or less, and a stress relaxation ratio of 7 or less. Transmission belt.