JPH0780533B2 - Conveyor belt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conveyor belt made of a thermoplastic resin.

BACKGROUND ART A conveyor belt is a woven fabric made of synthetic fibers, natural fibers, etc. (hereinafter referred to as “base fabric”), which has polyvinyl chloride,
Thermoplastic polyurethane, those produced by coating ionomer resin, etc. by calendering, those produced by applying adhesive treatment to the base fabric and adhering it to the resin sheet under hot pressure, or when extruding the resin sheet, The one manufactured by thermocompression bonding with the base cloth is often used. These belts are excellent in strength, but due to the fact that the base cloth is rich in water absorption and the surface of the base cloth has an uneven shape, molds and germs easily propagate, and the oils and fats attached There is a problem that it is difficult to remove minute and dust. Furthermore, when the belt meanders during driving, the resin layer on the surface is peeled off by being guided by the guide, the base cloth is exposed, the edges are fluffed, and dust is generated. These problems are fatal when the belt is used for transporting food or precision equipment.

On the other hand, an extrusion-molded single-layer polypropylene sheet or polyester elastomer sheet may be used as the conveyor belt. In this case, since the surface is smooth, dirt and germs are unlikely to adhere. In addition, fluffing as in the case of using the base cloth is also suppressed.

However, the conveyor belt using the above-mentioned single-layer resin sheet exhibits a warp in the width direction in which the front surface side becomes concave when it is continuously used. In the case where a conveyed product on the conveyor is detected by a photoelectric tube or the like, it becomes difficult to detect the conveyed product due to the rise of the side edge of the conveyor caused by the warp.

An object of the present invention is to suppress the occurrence of warpage in a conveyor belt made of a thermoplastic resin.

Means for Solving the Problem That is, as shown in FIG. 1, the conveyor belt according to the present invention has three thermoplastic resin layers of a surface layer 1, a core layer 2 and a back surface layer 3 integrated with each other. . The tensile elastic modulus of the resin forming each layer is increased in the order of the core layer, the front surface layer, and the back surface layer.

The ratio of the tensile elastic modulus of the front surface layer / back surface layer is preferably 1.1.
~ 5.1.

Action When the mechanism of warpage of a conveyor belt using a single-layer resin sheet was examined, the following was found.

When the belt is being driven by the pulley 4, especially immediately before the belt is placed along the peripheral surface of the pulley 4, due to the thickness of the belt, the tensile stress between the belt front surface side 5 and the belt back surface side tensile stress 6 is reduced. Makes a difference. When the belt 4 is moved along the pulley 4, the belt surface side becomes the outer peripheral surface and is pulled more than the belt back side, so the tensile stress 5 is the tensile stress 6
It is getting bigger.

The tension in the belt driving direction appears as contraction in the belt width direction. Then, depending on the amount of expansion in the belt driving direction based on the tensile stress on the front and back surfaces, a difference also occurs in the contraction amount in the width direction between the front and back surfaces, and as shown in FIG. A directional warp occurs. When it is desired to reduce the diameter of the pulley 4, the belt cannot satisfactorily follow the pulley unless the tensile elastic modulus of the belt is reduced. Therefore, the elongation of the belt due to the tension tends to increase, and the warp also increases. .

From the above knowledge, in the conveyor belt according to the present invention, the tensile elastic modulus of the surface layer is made larger than the tensile elastic modulus of the back surface layer, so that the difference in the elongation of the belt based on the difference in the tensile stress between the front and back surfaces of the belt. It becomes smaller on the back side and suppresses warpage in the belt width direction. The resin layer with the highest tensile elastic modulus is placed on the core layer of the belt to improve the creep resistance of the belt.However, for the bendability of the belt along the pulley, the material of the core layer is the surface. It does not contribute as much as the material of the layer and the back surface layer, and can be used as a conveyor belt for use with a small pulley diameter.

Example Next, an example of the present invention will be described together with a comparative example.

A combination of thermoplastic polyester elastomer resins having various tensile elastic moduli shown in Table 1 was used to co-extrude a three-layer sheet with a thickness constitution of surface layer / core layer / back surface layer = 0.53 / 0.55 / 0.53 mm. This was processed into a conveyor belt with a width of 200 mm × 5 m and a surface layer having a high tensile elastic modulus.

The results of measuring the amount of warp h (see FIG. 3) after the test was carried out under the following running conditions for the above-mentioned conveyor belt mounting test.

Running conditions Pulley diameter: φ150mm Tension: 4% Travel speed: 10m / min Conveyed object weight: 3kgf Travel time: 48 hours The resin types in Table 1 are as follows.

A: Brand name Perprene P150B Toyobo Co., Ltd. B: Trade name Perprene E450B Same as above C: Trade name Perprene P90BD Same as above D: Blend of A and C above Same as above E: Trade name Perprene P150BGF10 Same as above (containing 10% by weight glass fiber) From Table 1, it can be seen that the warp can be suppressed by making the tensile elastic modulus of the surface layer larger than the tensile elastic modulus of the back surface layer. From Examples 1, 2, and 4, the tensile elasticity of the surface layer / back surface layer is shown. It can be seen that it is even better if the ratio of the rates is in the range of 1.1 to 5.1.

The tensile elastic modulus of the core layer is set to the largest value among the three layers, and the set value may be appropriately determined according to the application such as the tension applied to the belt and the load of the conveyed product. In addition, the warp of the belt having a convex surface makes it easy for the conveyed object to slip off due to vibrations and the like, and therefore in some cases it is better to make the allowable range smaller than that of a warp having a concave surface.

Effects of the Invention As described above, the belt conveyor made of the thermoplastic resin according to the present invention has different tensile elastic moduli of the surface layer, the core layer, and the back surface layer, so that the warpage in the width direction is small and the creep resistance is high. The characteristics can also be retained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a conveyor belt according to the present invention together with its cross section, FIG. 2 is a cross sectional explanatory view showing a situation in which the belt warps, and FIG. 3 shows a state in which the warp of the belt is measured. It is the explanatory view shown. 1 is a front layer, 2 is a core layer, 3 is a back layer

Claims (2)

[Claims] 1. A conveyor belt in which three layers of thermoplastic resin layers of a surface layer, a core layer, and a back surface layer are integrated, and the tensile elastic modulus of the resin constituting each layer is the core layer, the surface layer,
Conveyor belts that are higher in the order of the back layer. 2. The ratio of the tensile elastic modulus of the front surface layer / back surface layer is 1.1.
The conveyor belt according to claim 1, wherein the conveyor belt has a size of about 5.1.