JP2604443B2 - Power transmission belt and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power transmission belt and a method for manufacturing the same.

(Prior Art) Various types of transmission belts, such as a poly-V belt, a low-edge belt, and a wrapped belt, are known. Basically, the transmission belt is buried between an extension portion, a compression portion, and both portions. For example, in the case of the poly V belt and the low edge belt, the upper surface of the elongate portion is covered with a rubberized canvas layer in the case of the wrapped belt. ing. In other words, the canvas layer is usually coated with friction rubber or glue rubber on both sides.

Thus, in manufacturing such a power transmission belt, a canvas coated with the friction rubber or the glue rubber is mounted on a mold, and a rubber, a tensile member, and a compression portion constituting the extension portion are formed thereon. A method is employed in which rubber is wound in order, vulcanized by a vulcanizer, and released from a mold.

Further, by applying a temperature-sensitive adhesive to the molding surface of the mold by spraying or the like, the canvas is brought into close contact with the molding surface, and a tensile member and an elastomer are disposed thereon and heated. There is also known a method in which the belt is cured by hardening, and the pressure-sensitive adhesive is lost in tackiness to facilitate release of the belt (for example, JP-A-53-6698).
No. 1). The above-mentioned temperature-sensitive adhesive contains a thermoplastic polymer substance, and when heated to a predetermined temperature or higher, melts and loses its adhesiveness.

(Problems to be Solved by the Invention) In the case of a conventional power transmission belt, applying friction rubber or glue rubber to the canvas improves the familiarity (adhesion) to a mold and vulcanization of the elongation portion. This is for improving the adhesion between the rubber and the canvas. However, when the transmission belt is driven, for example, on the back side of the belt, or when an idler is applied to the back side, the rubber coated on the canvas slides with the pulley, so that the rubber powder falls. In other words, it causes belt wear,
Abnormal sound and vibration may be generated due to adhesion by the rubber powder.

On the other hand, in the manufacturing method using the above-mentioned temperature-sensitive adhesive, although the belt is easily die-cut, the adhesive is hardened by cooling after the die-cutting and remains on the belt. As in the case of the friction rubber and the glue rubber described above, problems such as falling and sticking of belt abrasion powder come out.

By the way, we tried to fabricate a belt by applying rubber to only one side of the above canvas, but not only did the fabric's familiarity (adhesion) to the mold deteriorate, and the quality of the product varied, but also the vulcanization caused the canvas to vulcanize. Rubber oozes out on the surface of the film, and eventually causes problems such as falling of rubber powder and adhesion.

(Means for Solving the Problems) According to the present invention, at least an upper surface of a stretched portion of a belt body having a stretched portion, a compressed portion, and a tensile member in the longitudinal direction of the belt embedded between the two portions is a canvas layer. In a covered power transmission belt, if an appropriate amount of a cross-linking agent is added to the acrylic adhesive, the adhesive has adhesive properties at room temperature, but is cured by the crosslinking reaction when heated, resulting in substantial adhesive adhesion. By utilizing the fact that the canvas layer has no property and can be easily removed for the canvas layer, the above-mentioned problem caused by the adhesive property of the canvas layer to the pulley is solved.

That is, the invention of claim (1) is the above-described power transmission belt, wherein the canvas layer has a configuration in which a rubber layer is provided only on one side of the stretchable canvas, that is, only on the belt body side, and the other surface of the canvas is the acrylic-based It is characterized in that the cured layer due to the crosslinking of the adhesive is removed and the canvas itself is exposed on the outer surface of the belt.

In the method for manufacturing a power transmission belt according to the invention of claim (2), the acrylic adhesive containing a cross-linking agent is applied to the other surface of the elastic canvas coated with rubber on one side with respect to the molding surface of the mold. At least one of the other surface of the stretchable canvas and the molding surface of the mold is applied and attached, and the rubber constituting the extension portion, the tensile member, and the rubber constituting the compression portion are sequentially wound on the stretchable canvas, and the state is shown. And vulcanizing by heating and pressurizing, and releasing the molded product from the mold.

According to a third aspect of the present invention, in the method of the second aspect, the adhesive is an acrylic ester-based main monomer component that forms a soft segment having a low glass transition point. And a comonomer component forming a hard segment having a high glass transition point, wherein the comonomer component contains a monomer having a copolymerizable functional group, and the monomer has a functional group 1
A cross-linking agent in an amount of 0.5 equivalent or more, and an apparent glass transition point of -55 ° C to -10 ° C.

In this specification, the apparent glass transition point is a value of the entire adhesive before the crosslinking reaction by the crosslinking agent.

(Function) In the invention of claim (1), the canvas itself is exposed to the outside to constitute the outer surface of the transmission belt,
Since the canvas layer has no adhesive property, even if it comes into contact with the pulley, it does not partially adhere to the pulley, so that the rubber is not scraped off, and no abnormal noise or vibration is generated.

In the invention of claim (2), the stretchable canvas is adhered to the mold with an acrylic adhesive at a pressure of about the finger pressure without any gap, and the stretchable canvas, the tension member and the rubber constituting the compression member are wound. It can be prevented from being displaced or peeled off from the mold during attachment. And since the above-mentioned adhesive has a cross-linking agent, it causes a cross-linking reaction by heat at the time of the vulcanization treatment, and prevents the rubber from swelling itself and exuding to the mold side, and By losing the adhesive property by curing, the molded product can be easily released from the mold. The cured layer of the adhesive is thus brittle and can be easily removed from the canvas. The rubber constituting the extension portion is adhered to the canvas by a rubber applied to one surface thereof, and the canvas and the rubber constituting the extension portion are integrated by vulcanization.

In the invention of claim (3), since the adhesive contains a crosslinking agent in a ratio of 0.5 equivalent or more with respect to the functional group 1 of the monomer, a normal vulcanization temperature (for example, 150 to 200 ° C.)
, The crosslinking reaction proceeds in a relatively short time, the adhesive property is lost, and the mold is easily released from the mold. In this case, if the proportion of the crosslinking agent is less than 0.5 equivalent, smooth progress of the crosslinking reaction cannot be expected. The adhesive has a glass transition point of -55 ° C.
From the above, the adhesive is securely cured by the crosslinking reaction by the crosslinking agent and loses its adhesiveness, and since the glass transition point is -10 ° C or lower, the adhesive at room temperature is used. Good nature. That is, if the glass transition point is less than -55 ° C, even if the crosslinking reaction is carried out by adding 1 equivalent of a crosslinking agent, the adhesiveness is not sufficiently lost, and the glass transition point exceeds -10 ° C. In such a case, the adhesiveness at room temperature cannot be expected very much.

(Effects of the Invention) Therefore, according to the invention of claim (1), since the canvas itself is exposed to the outer surface of the transmission belt, it is possible to prevent the belt from being worn by the contact with the pulley, and the occurrence of abnormal noise and vibration. Can be.

According to the invention of claim (2), the stretchable canvas can be adhered to the mold without any gap, and the molded product can be easily released from the mold. It becomes easy to remove the layer where the adhesive has hardened, and the adhesion between the canvas and the belt body can be made good,
The transmission belt can be manufactured smoothly.

According to the invention of claim (3), an acrylic adhesive in which a crosslinking agent is blended in a ratio of 0.5 equivalent or more with respect to the functional group 1 of the monomer and an apparent glass transition point is -55 ° C to -10 ° C. Since the adhesive is used, the method of the invention of claim (2) can be carried out smoothly.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The power transmission belt shown in FIG. The belt 1 includes a belt main body 5 including an extension portion 2 made of rubber, a compression portion 3 made of rubber, and a tensile member 4 in the longitudinal direction of the belt made of a cord embedded between the two portions 2 and 3.
The upper surface of the extension 2 is covered with a canvas layer 6.

The elongating part 2 and the compressing part 3 can be formed of a known rubber compound such as chloroprene rubber, styrene-butadiene rubber, polyurethane rubber or the like according to the purpose of use of the belt. In addition, the tensile member 4 is a known glass cord, steel wire cord, Kevlar cord, polyester cord,
Nylon cords or the like are used and are spirally arranged in the longitudinal direction of the belt.

The specific structure of the canvas layer 6 is shown in FIG. 2, and is composed of an elastic canvas 7 and a rubber layer 8 provided on a surface of the canvas 7 on the belt body 5 side. It is exposed on the outer surface of the belt. The canvas 7 is provided with a woven fabric biased in the longitudinal direction of the belt. The rubber layer 8 can be obtained by subjecting the spread cloth 7 to friction, coating, dipping, or the like.

The poly-V belt 1 of this example is used for, for example, a multi-axis transmission shown in FIG. That is, in the figure, 10 is a driving pulley, 11 and 12 are driven pulleys, and 13 is an idle pulley applied to the back of the belt. In this case, the idle pulley 13 comes into contact with the outer surface of the canvas layer 6, that is, the canvas 7 itself. In such use,
In the belt 1, since the canvas layer 6 does not have adhesiveness,
Almost no part of the idle pulley 13 adheres to the idle pulley 13 and is rubbed, and almost no noise or vibration occurs.

 Next, a method for manufacturing the poly-V belt 1 will be described.

First, the canvas member constituting the canvas layer 6 can be obtained at normal temperature by the calendar method shown in FIG. That is,
First and second calendar means 14 and 1 composed of four rollers
5 are arranged side by side, so that the canvas 7 passes through the two calendar means 14 and 15 in order. Next, an acrylic adhesive containing a cross-linking agent is applied to the upper surface of the canvas 7 by the second calendar means 15 as indicated by reference numeral B.
In this case, the coating amount or the coating thickness of the adhesive is smaller than that of the rubber.

The acrylic adhesive comprises an acrylic ester-based main monomer (adhesive component) forming a soft segment having a low glass transition point, and a comonomer component (aggregating component, A comonomer with a modifying component), wherein the comonomer component contains a monomer having a copolymerizable functional group, and a crosslinking agent is blended in a ratio of 0.5 equivalent or more with respect to the functional group 1 of the monomer. The apparent glass transition point is between -55 ° C and -10 ° C.

As the main monomer component, a general acrylic ester can be used, for example, an acrylic ester,
It is preferable to use an acrylate having an alkyl group having about 4 to 10 carbon atoms, such as butyl acrylate and 2-ethylhexyl acrylate.

As the monomer having a functional group as the comonomer component, a carboxyl group, a hydroxyl group, having a functional group such as an amide group, for example, methacrylic acid, acrylic acid,
Itaconic acid, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, acrylamide,
Methylol acrylamide, glycidyl methacrylate, maleic anhydride and the like can be used.

Further, as the comonomer component, alkyl acrylate of lower alkyl group, alkyl methacrylate, for example, methyl acrylate and methyl methacrylate, and further copolymerizable with vinyl acetate, vinylidene chloride, styrene, acrylonitrile, acryloamide and the like. A monomer having a higher glass transition point may be used together with the above-mentioned monomer having a functional group.

As the cross-linking agent, epoxy-based, isocyanate-based, and the like can be used. For example, trimethylolpropane triglycidyl ether, phenol-blocked isocyanate, caprolactam-blocked isocyanate,
Preferred are blocked isocyanates such as oxime-blocked isocyanates, or adducts of tolylene diisocyanate.

 The composition of the adhesive in this example is shown below.

Isobutyl acrylate 100 parts by weight Acrylic acid 10 parts by weight Trimethylolpropane triglycidyl ether (crosslinking agent) 0.5 equivalents Ethyl acetate (solvent) Suitable amount In the above formulation, the crosslinking agent is acrylic acid having a copolymerizable functional group (carboxyl group). Of the above functional group. With this cross-linking agent removed,
Ethyl acetate (solvent) is used to adjust the acrylic monomer concentration to 30% by weight, 0.2% by weight of AIBN is added to the monomer as an initiator, and solution polymerization is performed for 6 hours in a nitrogen stream at a temperature of 70 ° C. and a capacity of 500 ml. A cross-linking agent was mixed with the obtained polymer to obtain an adhesive.

The apparent glass transition point of the obtained adhesive is -15 ° C.

Then, the canvas member 16 obtained as described above is wound around the mold 17 at room temperature so that the adhesive-coated layer 18 comes into contact with the mold 17 as shown in FIG. Since the belt 1 of this embodiment has only one canvas layer 6, the canvas member 16 is wound once. However, in the case of a plurality of layers, the belt member 16 is wound by the corresponding number of times. The ends of the canvas member 16 are connected to each other by being overlapped with each other. Next, a rubber sheet constituting the extension 2 is wound on the rubber coating layer 19 of the canvas member 16,
Wrap the cord for Tensile Body 4 spirally on top of it,
Further, a rubber sheet constituting the compression unit 3 is wound thereon.

Then, V is applied from the outside of the rubber sheet for the compression section 3
The vulcanizing treatment is performed by placing the rib forming mold on a vulcanizer and applying a pressure of about 20 minutes at 170 ° C. Then, after that, the molded product is released and cut in a circumferential direction at a predetermined width,
The canvas layer 6 is turned over so that it is on the outer peripheral side, and the adhesive coating layer is applied.
The belt 18 is cured by bridging and removed with a brush or the like to obtain a belt 1.

In the above manufacturing method, the canvas member 16 has adhesive properties at normal temperature to the adhesive coating layer 18. Even if the extension portion forming rubber or the like is wound thereon, there is no deviation from the mold 17. The adhesive layer 18 is cured by the heat of the vulcanization due to the crosslinking reaction (the crosslinking agent reacts with the carboxyl group of the acrylic acid) and loses the adhesive property. From the mold. Further, at the connection portion (overlapping portion) at the end of the canvas member 16, the adhesive layer 18 is hardened, so that the outer surface of the inner canvas 7 and the outer rubber coating layer 19 are interposed via this hardened layer. Will be glued between
Since the hardened layer is thin, the adhesive force between the outer surface of the inner canvas 7 and the outer rubber coating layer 19 is not significantly reduced, and does not cause any problem.

Although the above embodiment relates to a poly V belt, the present invention relates to a low edge type V belt 20 shown in FIG.
The wrapped V-belt 21 shown in the figure can also be implemented basically in the same manner as the above embodiment. In the low-edge and wrapped V-belts 20, 21, 22, 23
Is an extension portion, 24 and 25 are compression portions, 26 and 27 are tensile members, 28 and 29 are canvas layers, and the canvas layers 28 and 29 have the same configuration as the previous embodiment.

Next, the evaluation test of the poly-V belt 1 and the results thereof will be described.

—Adhesion Evaluation Test— FIG. 8 shows a test apparatus. That is, in the figure, 32 is a driving pulley driven at a rotation speed of 3500 rpm, 33 is a driven pulley of 1PS, 34 is an idle pulley, and each of the pulleys 32-34 has a diameter of 100 mm. Looking at the relationship between the PV value and the belt slip length in this test apparatus, as shown in FIG. 9, the conventional canvas having both sides coated with rubber has characteristics indicated by broken lines. On the other hand, in the case of the belt of the example, as indicated by the plots indicated by the circles, the slip length up to the occurrence of sticking was much longer than that of the conventional belt, and
It can be seen that the exposure of the belt has a great effect on preventing the belt from sticking.

It should be noted that P is the surface pressure generated on the belt, V is the belt sliding speed, and the belt sliding length is represented by V × t. t is the time (sec) until the occurrence of adhesion.

-Wear evaluation test-The test apparatus shown in Fig. 8 has the same driving pulley 33 and idle pulley 34 as those in the previous evaluation test, the driven pulley 33 is 5PS, and the belt load is 50kgf.
The belt running time and the rate of change in weight and thickness of the belt were as shown in FIG. In other words, it can be seen from the figure that the belt of the example has less wear of the belt than the conventional canvas in which both surfaces are coated with rubber.

Next, for an example using an adhesive of another formulation,
This will be described in comparison with a comparative example.

<Blending and manufacturing method> The blending (parts by weight) of the examples is shown in the upper column of Tables 1 and 2 together with those of the previous examples. Table 2 shows comparative examples.

In the above formulation, the epoxy-based crosslinking agent is trimethylolpropane triglycidyl ether, and the isocyanate-based crosslinking agent is phenol-blocked isocyanate. Then, a transmission belt was manufactured by using this composition in the same manner as in the previous example to obtain a pressure-sensitive adhesive, and the moldability and the mold release property were evaluated. Further, in order to quantitatively evaluate, an adhesion test described below was performed. The results are shown in Tables 1 and 2 and Table 2 below. In addition, this first
In Tables 1 and 2 and Table 2, the glass transition point is the apparent glass transition point.

<Adhesive force test> A tacky adhesive was applied to the surface of the cotton canvas, and the coated surface was adhered to a stainless steel plate (with a hand roller), and the adhesive force before and after heating was measured. The heating was performed at 150 ° C. for 15 minutes, and the adhesive strength was measured by peeling the cotton canvas at a rate of 50 mm / min.

<Discussion> In Examples 1 to 8 (1 in Table 1), an epoxy-based crosslinking agent was used, and in Examples 9 to 14, (2 in Table 1), an isocyanate-based crosslinking agent was used.

In Examples 1 to 3, isobutyl acrylate was used as a main monomer component, and the amount of the epoxy-based crosslinking agent was changed. The apparent glass transition point is -15 ° C. The adhesive strength before heating is relatively high at 1.9 kgf / 25 mm even when the amount of the crosslinking agent is large. If the adhesive strength before heating is 1.5 kgf / 25 mm or more, it is easy to make the canvas adhere to the mold,
It can be seen that good moldability can be obtained in the above examples.
On the other hand, the adhesive strength after heating is as low as 0.5 kgf / 25 mm even when the amount of the crosslinking agent is small (0.5 equivalent). If the adhesive strength after the heating is 0.5 kgf / 25 mm or less, the canvas is easily peeled off from the mold, and thus it can be seen that there is no problem in the mold removability in the above embodiment.

Comparative Examples 1 to 3 corresponding to the above Examples 1 to 3 are those in which the amount of the crosslinking agent is reduced, but the adhesive force before heating is not problematic, but the adhesive force after heating is high. There is a problem in the above-mentioned mold releasability. This shows that the amount of the crosslinking agent is preferably 0.5 equivalent or more.

Examples 4 to 6 used n-butyl acrylate as the main monomer component, and Examples 7 and 8 used a combination of isobutyl acrylate and n-butyl acrylate, and a mixture of n-butyl acrylate and 2 acrylate. -In combination with ethylhexyl. Although the apparent glass transition point is lower than that of Examples 1 to 3, there is no problem in both the moldability and the mold release property, and the glass transition point of Example 8 (-) is the lowest. Even at 54 ° C), there is no problem in terms of mold release.

On the other hand, Comparative Example 4 uses 2-ethylhexyl acrylate as the main monomer component and uses 1.0 equivalent of the crosslinking agent, but has an apparent glass transition point as low as -61 ° C. In the case of Comparative Example 4, although there is no problem in terms of moldability, there is a problem in that the adhesive force after heating is high and the mold removability is high. This indicates that if the glass transition point is too low even if the amount of the cross-linking agent is increased, the adhesive will not cure sufficiently and the adhesive strength after heating will increase.

Next, in Examples 9 to 14 using the isocyanate-based cross-linking agent, the moldability and the mold release were all good. For example, in Example 12, the adhesive strength before heating is low,
Nevertheless, the value is 1.5 kgf / 25 mm, and there is no problem in the above moldability. In addition, the adhesive force after heating is slightly higher in Example 9 than in the corresponding Example 3 using the same equivalent amount of the epoxy-based crosslinking agent, but is still 0.5 kgf / 25 mm or less. But no problem.

In contrast, in the case of Comparative Examples 5 to 7 corresponding to Examples 10 to 12, the small amount of the cross-linking agent was reflected as it was, and the adhesive force after heating was high, and in terms of mold removability, It turns out there is a problem. In Comparative Example 8, although the amount of the crosslinking agent was 1 equivalent, there was a problem in that the adhesive strength before heating was low and moldability was low. This is because the apparent glass transition point is as high as + 3.8 ° C. due to the inclusion of methyl methacrylate, and therefore, it is understood that the high glass transition point is not desirable.

<Relationship Between Heating Temperature and Adhesive Force> With respect to Examples 1 and 3 and Comparative Example 1, a heating test was performed at each temperature, and each adhesive force was measured. The heating time is
12 hours. The test results are shown in FIG.

From the figure, it can be seen that the adhesive strength decreases with the amount of the crosslinking agent. In the case of the example, the adhesive force was reduced to 0.2 kgf / 25 mm or less by heating at 80 ° C., and it can be seen that good die-releasability was obtained due to loss of adhesiveness.

In addition, in the case of the example, even if heating at 170 ℃, 15 minutes, the adhesive strength is reduced to about the above value, but at a temperature of 170 ℃ or more,
The heating time required to reduce the adhesive strength to about the above value is further reduced. Further, if the time is longer even at a temperature of 80 ° C. or lower, the adhesive strength is naturally reduced to the above value.

The isocyanate-based cross-linking agent is a blocked isocyanate and starts the reaction at a high temperature of 130 to 180 ° C., so that the workability is good. That is, FIG. 12 shows the change over time of the adhesive strength at room temperature (21 ° C.) for the adhesive A using phenol-blocked isocyanate and the adhesive B using an adduct of tolylene diisocyanate. FIG. 13 shows the change with time in the adhesive force at 150 ° C. As can be seen from these figures, in the case of phenol-blocked isocyanate, at room temperature, the adhesive force hardly changes even after 6 days, but at 150 ° C., the adhesive force is reduced in a short time, and the hot life is long, and The work can be completed in a short time, and it can be said that it is easy to use.

In the above examples, acrylic acid was used as a comonomer component having a functional group capable of copolymerization. With only a slight change in time, basically the same result as in the above embodiment can be obtained.

Further, the solvent in the above embodiment is ethyl acetate, but it goes without saying that toluene and other solvents can be used.

Further, in the above-described embodiment, the adhesive is applied to the stretchable canvas, but the same operation and effect as in the embodiment can be obtained by applying the adhesive to the molded cotton of the mold.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention, FIG. 1 is a perspective view showing a poly V belt in partial cross section, FIG. 2 is a cross section of a canvas layer, FIG.
FIG. 4 is a side view showing an example of using a transmission belt, FIG. 4 is a side view showing a manufacturing process of a canvas member, FIG. 5 is a side view showing winding of the canvas member around a mold, and FIG. 6 and FIG. FIG. 8 is a side view showing a belt evaluation test device, FIG. 9 is a graph showing an adhesion evaluation test result, FIG. 10 is a graph showing a wear evaluation test result, FIG. 11 is a graph showing the relationship between the heating temperature of the adhesive and the adhesive strength, FIG. 12 is a graph showing the change over time of the adhesive strength at room temperature (21 ° C.) of the adhesive, and FIG. It is a graph which similarly shows the time-dependent change of the adhesive force in 150 degreeC. 1 ... Poly V belt, 2 ... Extended section, 3 ... Compressed section, 4
... Tensile body, 5 ... Belt body, 6 ... Canvas layer, 7 ...
Canvas, 8 ... rubber layer, 16: canvas member, 17: mold, 18
…… Adhesive coating layer, 19… Rubber coating layer

Claims (3)

(57) [Claims] 1. A power transmission belt in which at least an upper surface of an extension portion of a belt body having an extension portion, a compression portion, and a tension member in a belt longitudinal direction embedded between the two portions is covered with a canvas layer. A power transmission belt, wherein the canvas layer comprises an elastic canvas and a rubber layer provided only on one side of the canvas, and the rubber layer is located on the belt body side and the canvas is exposed on the outer surface of the belt. . 2. The molding method of claim 2, wherein the other surface of the elastic canvas coated with rubber is coated with an acrylic adhesive containing a crosslinking agent on the other surface of the mold. Applied to at least one of the surface and attached, the stretch portion constituting rubber, the tensile member and the compressing portion constituting rubber are sequentially wound on the stretchable canvas, and subjected to a vulcanization treatment by heating and processing in that state,
A method for manufacturing a power transmission belt, comprising releasing a molded product from a mold. 3. The adhesive agent is a copolymer of a main monomer component of an acrylate ester forming a soft segment having a low glass transition point and a comonomer component forming a hard segment having a high glass transition point. Wherein the comonomer component contains a monomer having a copolymerizable functional group, and a
The method for producing a power transmission belt according to claim 2, wherein the composition is blended at a ratio of equal to or more than an equivalent and the apparent glass transition point is set at -55C to -10C.