JP2008179464A - Conveyor belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveyor belt, hardly stained, having flexibility to easily wrap around a pulley without slipping, hardly elongating in traveling, and having strength endurable against repetitive use. <P>SOLUTION: This conveyor belt is formed as a two-layer structure by arranging a polypropylene-based resin layer on a surface of polypropylene cloth. Tensile strength in the traveling direction of the conveyor belt is set to 450 N or more, and tensile elongation in the traveling direction is set less than 25%, and the problem can thus be solved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conveyor belt for transporting chicken manure in a poultry house, which is less likely to generate contamination and foreign matter, and has excellent durability and running performance.

  Conveyor belts are widely used for conveying articles, such as uses for food and processed food products, uses for processed materials and appliance parts, uses for waste, and uses for livestock houses. Such a conveyor belt requires durability, scratch resistance, wear resistance, and the like.

  Generally, a conveyor belt made of synthetic resin such as polyurethane, polyvinyl chloride, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer is widely used as the conveyor belt. However, when these synthetic resins are used, they have drawbacks such as hydrolysis and deterioration during use. Further, these synthetic resin conveyor belts are easily contaminated, and are not suitable for use in, for example, poultry manure transportation in poultry houses.

  In view of this, a conveyor belt made of polyolefin such as polyethylene or polypropylene, which is known to be difficult to get dirty in a poultry house or the like and has no such drawbacks, is used.

  A polypropylene resin single layer conveyor belt is known as a polyolefin conveyor belt. A polypropylene resin single-layer conveyor belt is smooth and difficult to get dirty, but tends to be easily stretched by the tension in the running direction. If a high-strength resin is used to suppress this elongation, problems such as a decrease in flexibility and difficulty in fitting the conveyor belt to the pulley, and a tendency to breakage occur. On the other hand, if the thickness of the conveyor belt is reduced, the strength is insufficient and the life of the conveyor belt is reduced.

Therefore, in order to solve the above-mentioned problems that are easily stretched in the running direction and come off from the pulley or break, the Japanese Utility Model Publication No. 59-212 (Patent Document 1) discloses a polypropylene foam spread yarn woven cloth. Discloses a belt base material for a belt conveyor having a three-layer structure in which polypropylene layers are provided on both sides. Since the belt base material of this three-layer structure uses a polypropylene foam spread yarn woven cloth, the belt base material is difficult to extend in the running direction and is excellent in durability. However, since a polypropylene layer having a smooth surface is also laminated on the back side of the belt base material, there is a drawback that it is difficult to slip and wind up on a pulley. In addition, since the belt base material is thick due to the three-layer structure and is inferior in flexibility, there is also a problem that it is difficult to adapt to the pulley. In order to improve flexibility, if the total thickness of the belt base material is reduced, each layer must inevitably be thinned, the polypropylene layer tends to break, the impact resistance of the belt base material deteriorates, There is a risk that it may easily extend in the direction of travel. Further, the three-layer structure is disadvantageous in terms of cost because the production process such as laminating work becomes complicated.
Japanese Utility Model Publication No.59-212

  The inventors of the present invention have been made in view of the problems of the prior art, and the purpose of the invention is to make it difficult to get dirt, flexible to easily wind around a pulley without slipping, and traveling. The inside is to provide a conveyor belt that is difficult to stretch. Another object of the present invention is to provide a durable conveyor belt having a strength equivalent to that of a three-layer structure so that it can withstand repeated use.

  As a result of various studies to solve the above-mentioned problems, the present inventors have found that the problem can be solved by providing a polypropylene resin layer on the surface of the polypropylene cloth to form a two-layer structure. The invention has been completed.

  That is, the invention according to claim 1 of the present invention is a conveyor belt having a two-layer structure in which a polypropylene resin layer is provided on the surface of a polypropylene cloth, and the tensile strength in the running direction of the conveyor belt is 450 N or more, In addition, the present invention relates to a conveyor belt (the tensile strength and tensile elongation of the present invention conform to JIS K-6732) characterized in that the tensile elongation in the running direction is less than 25%.

  The invention according to claim 2 of the present invention is characterized in that the polypropylene cloth has a tensile strength in the running direction of the conveyor belt of 300 N or more and a tensile elongation in the running direction of less than 25%. This relates to the conveyor belt according to 1.

  The invention according to claim 3 of the present invention relates to the conveyor belt according to claim 1 or 2, which is for conveying chicken manure in a poultry house.

  By providing a polypropylene resin layer on the surface of the polypropylene cloth to form a two-layer structure, it is possible to provide a conveyor belt that easily winds around a pulley without slipping. In addition, by using the polypropylene cloth of the present invention, it is possible to provide a conveyor belt that has the same strength as the three-layer structure and is less stretched in the running direction. Further, by adopting a two-layer structure, it is possible to give the conveyor belt flexibility, and further, it is possible to improve productivity and reduce costs.

  The conveyor belt of the present invention has a two-layer structure in which a polypropylene resin layer (hereinafter referred to as “PP resin layer”) is provided on the surface of a polypropylene cloth (hereinafter referred to as “PP cloth”). The present invention provides a conveyor belt that is excellent in durability, easy to adjust to a pulley, and is not easily soiled by providing a smooth PP-based resin layer on the surface of a PP cloth having a high tensile strength that hardly stretches in the running direction of the conveyor belt. Obtainable. The conveyor belt of the present invention is particularly suitably used for conveying chicken dung in a poultry house.

  Examples of the polypropylene resin used in the PP resin layer of the present invention (hereinafter referred to as “PP resin”) include propylene homopolymers and propylene and α-olefins such as ethylene, butene-1, and pentene-1. A random or block copolymer composed of one or more kinds, a modified polypropylene modified with maleic anhydride, or the like can be used. Among them, a propylene block copolymer is preferable from the viewpoint of impact strength and crack strength. Moreover, as long as the effects of the present invention can be obtained, a resin such as low-density polyethylene or ethylene-α-olefin may be mixed for imparting flexibility. Moreover, in terms of recycling, a recycled polyethylene resin may be mixed.

  Matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, antistatic agents, dyeing improvers, lubricants or adhesion improvers are added to such PP resins as necessary. Any of those other than those which adversely affect the properties of the present invention depending on the addition can be used. Also, it is preferable to add a white pigment to the PP resin because dirt is conspicuous and cleaning is easy.

  The thickness of the PP resin layer is preferably about 0.3 to 1.5 mm. If it is less than 0.3 mm, the impact resistance performance as a conveyor belt may not be maintained. On the other hand, if it exceeds 1.5 mm, the flexibility of the conveyor belt is impaired, and the weight of the conveyor belt itself increases, which may cause a problem in running performance.

When the PP cloth of the present invention is used for a conveyor belt, a PP cloth having a tensile strength of 300 N or more in the traveling direction and a tensile elongation in the traveling direction of less than 25% is used. When the tensile strength is less than 300N, it is difficult to maintain the strength as a conveyor belt, and when the tensile elongation is 25% or more, it becomes easy to stretch in the running direction of the conveyor belt, and when chicken droppings are loaded, the pulley -There is a risk of disengagement.

  The PP cloth of the present invention is formed by weaving a thread-like material obtained by uniaxially stretching a commonly used foamed or unfoamed polypropylene film. The filamentous material can be obtained by, for example, slitting a polypropylene film to a predetermined width and uniaxially stretching, or slitting a film after uniaxially stretching the film. The thickness of the filamentous material is preferably 1000 to 2000 denier, more preferably 1300 to 1700 denier.

  The obtained filamentous material can be made into a cloth-like body by weaving into plain weave, twill weave, oblique weave, silk weave, double weave, imitation weave or the like. Among these, from the viewpoint of strength and workability, a plain weave is preferred in which the length and width are 10 to 20 per inch and the warp and weft are alternately crossed up and down.

  When a PP cloth is woven with the above-described thickness of the filamentous material as described above, the thickness of the PP cloth is about 0.2 mm to 0.6 mm. When the thickness of the PP cloth is less than 0.2 mm, it is difficult to obtain physical properties required for a conveyor belt. On the other hand, when the thickness exceeds 0.6 mm, the total thickness of the conveyor belt is increased and the flexibility is impaired, and also disadvantageous in terms of workability and cost.

  The PP cloth may be subjected to surface treatment on the back surface (side on which the PP resin layer is not provided) in order to prevent contamination. At this time, it is preferable to use a polypropylene-based paint from the viewpoint of adhesion and recyclability. The coating thickness of the polypropylene paint is preferably about 0.02 mm to 0.07 mm. In addition, the surface treatment has an advantage that a wide sheet can be produced, and fraying and fluffing at the end of the PP cloth that occurs when a conveyor belt is produced by slitting to a desired width.

  As a method of laminating the PP resin layer on the PP cloth, an extrusion molding method in which the polypropylene resin is extruded while being heated and melted and pressure-bonded to the PP cloth, a method of coating the PP cloth with the PP cloth, and forming a sheet with the PP cloth. Although there is a method of adhering PP resin with an adhesive, etc., an extrusion method is preferred. By extrusion molding, the PP-based resin enters between the textures of the PP cloth, so that the adhesive strength is improved and the PP cloth is less likely to fray.

  The physical properties of a conveyor belt in which PP-based resin is laminated on PP cloth require that the tensile strength in the running direction of the conveyor belt is 450 N or more and the tensile elongation in the running direction is less than 25%. If the tensile strength is less than 450 N, the conveyor belt may be cracked or broken when the conveyor belt is running, thereby reducing the life of the conveyor belt. Further, if the tensile elongation is 25% or more, there is a possibility that the belt stretches in the running direction and sags and the conveyor belt comes off from the pulley.

  The thickness of the conveyor belt is preferably 0.5 mm to 2.0 mm. If it is less than 0.5 mm, the strength is insufficient, and if it exceeds 2.0 mm, the flexibility is inferior, making it difficult to be wound on a pulley, increasing the weight of the conveyor belt, and causing problems in running performance. is there.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited by an Example.

(Example 1)
Polypropylene resin (DC-8 made by Nippon Polypro Co., Ltd.) is heated and melted into a plain woven PP cloth (thickness 0.4 mm) woven with 1500 denier yarns at 15 lengths and widths per inch by extrusion laminating. The laminate was laminated to a total thickness of 0.9 mm and slit to a width of 40 cm to obtain a conveyor belt. The physical properties of PP cloth are shown in Table 1.

(Comparative Example 1)
The polypropylene resin used in Example 1 was extrusion-molded to produce a 0.9 mm-thick polypropylene resin single-layer sheet, which was slit to a width of 40 cm to obtain a single-layer conveyor belt.

(Comparative Example 2)
The polypropylene resin used in Example 1 was extruded and laminated on both sides of the PP cloth used in Example 1 so that each side had a thickness of 0.25 mm, slit into a width of 40 cm, and 3 layers having a total thickness of 0.9 mm A structured conveyor belt was obtained.
Table 1 shows the tensile strength and tensile elongation of the PP cloth used in Example 1 and Comparative Example 2.

The conveyor belts obtained in Example 1 and Comparative Examples 1 and 2 were evaluated as follows.
(1) Tensile Strength A test piece having a width of 10 mm was pulled at a speed of 200 mm / min with a tensile tester, and a load when the test piece was cut was defined as tensile strength (according to JIS K-6732).
(2) Tensile elongation A test piece having a width of 10 mm was pulled at a speed of 200 mm / min with a tensile tester, and the elongation when the test piece was cut was defined as tensile elongation (according to JIS K-6732).
(3) Pulley-winding A test conveyor belt having a width of 30 cm was prepared, and the ease of winding the pulley was evaluated at a traveling speed of 50 mm / min with a pulley having an outer diameter of 30 cm.
〇 Easy to wind up × These results are difficult to slip and take up.

  As is apparent from Table 1, those according to this example are excellent in both tensile strength and tensile elongation, and pulley winding is also good. Since the polypropylene single layer sheet of Comparative Example 1 has low tensile strength and high tensile elongation, it cannot withstand medium to long-term use. Comparative Example 2 has sufficient tensile strength and tensile elongation, but a PP-based resin layer is also formed on the back surface, so that it is difficult to wind around the pulley, and there is a problem when actually used as a conveyor belt.

Claims (3)

  A conveyor belt having a two-layer structure in which a polypropylene resin layer is provided on the surface of a polypropylene cloth, the conveyor belt has a tensile strength in the running direction of 450 N or more and a tensile elongation in the running direction of less than 25%. Conveyor belt characterized by that.   The conveyor belt according to claim 1, wherein the polypropylene cloth has a tensile strength in the running direction of the conveyor belt of 300 N or more and a tensile elongation in the running direction of less than 25%. The conveyor belt according to claim 1 or 2, wherein the conveyor belt is used for transporting chicken manure in a poultry house.