JPH08324738A - Conveyor belt - Google Patents

Abstract

PURPOSE: To provide a light and high tensile conveyor belt with improved durability without generation of rusts or without troublesome wastes by using a reinforced cord where the organic fiber filament bundles having the specific tensile strength as a reinforcement layer embedded in the longitudinal direction of a belt body are stranded. CONSTITUTION: A reinforcement layer 3 is provided with a plurality of reinforcement cords 3A arranged along the longitudinal direction of a belt body 2. A yarn 3a is formed by twisting a plurality of organic fiber filament bundles (f) whose tensile strength is >=15g/d, a strand 3b is formed by twisting a plurality of these yarns 3a, and a plurality of the strands 3b are twisted to form reinforcement cords 3A. The tensile strength of the reinforcement cords 3A is >=10g/d, and its diameter is 2-15mm. A core yarn 10 having the denier number of 1-15% of the total denier number of the reinforcement cord 3A is inserted in the twist center part N of the reinforcement cord 3A. The core yarn 10 comprises the organic fiber filament bundles (h) of larger elongation than that of the organic filament bundles (f) comprising the reinforcement cords 3A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyor belt, and more particularly to a conveyor belt which is lightweight, has high tension and is extremely durable.

[0002]

2. Description of the Related Art Generally, a conveyor belt has a structure in which a reinforcing layer is embedded along the longitudinal direction of an endless belt-shaped belt body made of rubber, thermoplastic resin, thermosetting resin or the like. Heretofore, a canvas belt using a woven cloth made of an organic fiber typified by nylon fiber, polyester fiber or the like as the reinforcing layer and a steel conveyor belt using a steel cord have been known. Generally, a canvas belt has an advantage that it is lighter in weight than a steel cord belt, but since it has a lower tensile strength than a steel cord belt, a high tensile strength of 500 Kgf / cm or more is required. It is not suitable as a reinforcement layer for various conveyor belts. On the other hand, the steel cord conveyor belt has a diameter of 2 mm to 1 formed by twisting many steel wires together.
A steel cord with a thickness of about 5 mm and high tensile strength,
It has a structure in which a plurality of wefts are embedded substantially parallel to the longitudinal direction of the conveyor belt without using weft threads like woven cloth.

Since the steel cord having high tensile strength is used and the cord is used as the reinforcing layer, the finger having high joining efficiency (joining strength) at the endless joining portion of the conveyor belt is used. -Advantages of being able to provide a conveyor belt that is splicable and can withstand high tension. However, since the steel conveyor belt uses a steel for its reinforcing layer, rust occurs due to water intrusion when used in a heavy and heavy environment or when rubber cracks. However, there is a problem that adhesive breakage and cord breakage are likely to occur. There is also a problem that disposal of a used conveyor belt is extremely complicated. Further, with recent environmental problems and deterioration of economic environment, there is a strong demand for a conveyor belt which is lighter in weight, has high tensile strength, and has a long life.

As a method for solving such a problem, a conveyor belt has recently been developed in which aramid fiber having high tensile strength among organic fibers is used as a woven fabric for a reinforcing layer. However, a conveyor belt using an aramid fabric as a reinforcing layer has a woven structure as a reinforcing layer even if the finger-splice structure with the highest endless efficiency is applied to the endless part (joint part). Has a limit, and the one having a tensile strength of about 2000 Kgf / cm is a practically usable limit.

Even if an endless method with extremely high endless efficiency is developed, since the aramid fiber has a woven structure, the high strength originally possessed by the aramid fiber cannot be fully utilized and the tensile strength is Approximately 2000 kg
It is practically impossible to produce a woven fabric having a durability exceeding f / cm. Furthermore, when a woven structure is used, if notches such as cracks are formed at both widthwise end portions of the conveyor belt, there is a problem that the conveyor belt is easily broken due to stress concentration. Therefore, it has been desired to develop a novel conveyor belt which is lightweight and can be used even in a region where a tensile strength exceeding 2000 kgf / cm is required.

[0006]

DISCLOSURE OF THE INVENTION The object of the present invention is to have a light weight and a high tensile strength, and to prevent the generation of rust and the complexity of disposal,
It is to provide a conveyor belt having excellent durability.
Another object of the present invention is to provide a conveyor belt capable of improving fatigue strength and maintaining a longer life.

[0007]

The present invention to achieve the object is to provide a belt-shaped belt body with a tensile strength of 10 g / d, which is formed by twisting organic fiber filament bundles having a tensile strength of 15 g / d or more along the longitudinal direction thereof. d or more, diameter 2 to 15 mm
In a conveyor belt in which a plurality of reinforcing cords are embedded in the belt main body width direction substantially in parallel at a predetermined interval to form a reinforcing layer, the reinforcing cord is formed by twisting a plurality of organic fiber filament bundles into a yarn. A plurality of these yarns are twisted together to form a strand, and a plurality of these strands are twisted together to form a three-step twisted structure of lower twist, middle twist, and upper twist, and the reinforcement cord An organic fiber filament for inserting a core yarn having a denier number of 1 to 15% of the total denier number of the reinforcing cord into the twisted central portion of the cord and forming the reinforcing cord with the core yarn. It is characterized by being composed of yarns made of organic fibers that have a greater elongation than the bundle.

[0008]

The present invention is constructed as described above, and as a reinforcing layer embedded in the longitudinal direction of the belt body, a bundle of organic fiber filaments having a specific tensile strength is twisted together to form a reinforcing core having the above diameter and tensile strength. -Using a cord, the reinforcing cord ply-twists the organic fiber filament bundle, middle twist,
By forming it with a three-stage twist structure consisting of a top twist, it has high tension and can improve the durability of the conveyor belt, and it is used without the occurrence of rust such as steel cord. Disposal of the conveyor belt will not be complicated.

Further, if only a reinforcing cord having the above-mentioned diameter and tensile strength and having a simple three-stage twist structure is used, when tension is applied, the contact point of the strand at the center of the cord twist cross section. The fiber filaments are bent at an acute angle at the center of the twisting, and the filaments are buckled and flattened at the portions bent at the acute angles due to the repeated tension load, and cracks occur. In the central portion of the twisted cords, the denier number is 1 to 15% of the total denier number of the reinforcing cord,
Since the core yarn composed of the organic fiber filament bundle having a larger elongation than the organic fiber filament bundle constituting the reinforcing cord is inserted, the core yarn acts as a cushioning material,
As a result, it is possible to reduce deformation of the contact portion that causes angular contact of the strands. Therefore, as a result of suppressing the occurrence of cracks in the organic fiber filaments that make up the reinforcing cords that come into contact with each other at the cord twist center, the fatigue strength is improved and the life of the conveyor belt can be kept longer. Become.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective sectional view of a main part of the conveyor belt of the present invention with a part cut away.
Has a structure in which a reinforcing layer 3 is embedded along the longitudinal direction of a belt body 2 on an endless belt made of rubber, thermoplastic resin, thermosetting resin, or the like.

The reinforcing layer 3 has a plurality of reinforcing codes 3A arranged along the longitudinal direction of the belt body 2, and these reinforcing codes 3A are predetermined in the width direction of the belt body 2. It is arranged to be substantially parallel at intervals of. Figure 2 (a)
As shown in, the reinforcing cord 3A forming the reinforcing layer 3 is
Organic fiber filament bundle f having a tensile strength of 15 g / d or more
(Here, the organic fiber filament bundle is several μm to several tens μm.
Is an aggregate of a large number of ultra-thin filaments that are substantially untwisted, and is generally called a yarn, and is a yarn (here, a plurality of organic fiber filament bundles are twisted together). 'Defined in the present invention) 3a
A plurality of these yarns 3a are twisted together to form a strand 3b, and a plurality of these strands 3b are twisted together to form a lower twist obtained by twisting an organic fiber filament bundle f and twisting the yarn 3a. It has a three-stage twisted structure of a middle twist and a twisted upper twist in which the strands 3b are twisted, and the reinforcing cord 3A has a tensile strength of 10 g / d or more and a diameter of 2 mm to 15 mm.

Further, a core yarn 10 as a cushioning material is continuously inserted along the longitudinal direction of the reinforcing cord 3A at the twisted central portion N of the reinforcing cord 3A. This core thread 10
Is composed of a yarn composed of an organic fiber filament bundle h having a greater elongation than the organic fiber filament bundle f constituting the reinforcing cord 3A, and the total number of denier is the total number of denier of the reinforcing cord 3A. 1 to 1 of the number of denier (excluding core yarn 10)
It is in the range of 5%. Here, the organic fiber filament bundle f is used as the reinforcing cord, and by using the finger splicing method by using the cord, the strength of the endless joint can be further enhanced and the tensile strength is high. This is not only because it is possible to manufacture a conveyor belt, but also to avoid the problem that the thickness of the conveyor belt becomes too thick when a woven fabric is used and the reduction in notch strength.

As a method other than the three-step twist structure of the present invention for making the reinforcing cord 3A, a plurality of organic fiber filament bundles f are gathered and a lower twist is added as shown in FIG. 2 (b). Reinforcing cord 4A by forming multiple strands 4a
The method of twisting in two stages of lower twist and upper twist,
(C), a plurality of fiber filament bundles f are collected to form a twisted yarn 5a, and a plurality of these yarns 5a are collected to be twisted to form a strand 5a.
After forming b, a braid reinforcement cord 5A is formed by braiding a plurality of the strands 5b into a braid shape (here, 6 when the number of the strands 5b is 6 is 6 and when 8 is 8) As shown in FIG. 2 (d), a plurality of fiber filament bundles f are gathered and twisted by gathering a plurality of fiber filament bundles f on the outside of the core yarn 6a to which twist is applied. There is also a method of obtaining a braid reinforcing cord 6A containing a core yarn, which is braided into a braid shape by using a plurality of yarns 6b to which is added, but in either method, the strength utilization factor is low and the cord has a high tensile strength. In order to obtain a cord, there is a problem that the amount of fiber used increases and the cord must be thickened, and the fatigue strength is inferior.

In this way, the reinforcing cord 3A extending in the longitudinal direction of the reinforcing layer 3 embedded in the belt main body 2 is formed into a three-stage twist structure in which the lower twist, the middle twist and the upper twist are performed, and the diameter and the tensile strength are By setting in the above range,
It is lightweight, has high tensile strength, and can improve the durability of the conveyor belt. Moreover, it does not cause rust such as steel cord, and the used conveyor belt can be easily discarded. be able to.

If the strands 3b are simply twisted and the three-stage twisted structure 3A 'is set by setting the diameter and the tensile strength as described above, as shown in FIG. 3, the twisted strands 3b are When tension is applied (a)
From the above state, as shown in (b), the contact point of the strand 3b at the cord twist center O is deformed so as to form a square contact.

As a result, the organic fiber filament bundle f forming each strand passing through the center O is bent at an acute angle at the position of the center O, and when this tension is repeatedly applied, the organic fiber filament bundle f in the twisted center O is in the organic fiber filament bundle f. Filament is buckled and flattened, cracks occur in the filament starting from that point, and the filament fibrillation
The present inventors have found that the reduction of strength is promoted by the electron microscope analysis after the running test of the conveyor belt, but as a result of earnest research on a method for improving it,
It has been found that a cushioning material may be provided to alleviate the contact of the contact portion in the strand 3b.

That is, a yarn made of an organic fiber filament bundle h having a larger elongation than the organic fiber filament bundle f constituting the reinforcing cord 3A is used as the core yarn 10 and the thickness thereof is set as described above. It is to be inserted between the strands 3b. As a result, even if tension is applied to the reinforcing cord 3A and the twisted strands 3b are deformed while maintaining the uniformity as the reinforcing cord 3A, the core yarn 10 is not deformed as shown in FIG. Since the organic fiber filament bundles f are in contact with each other at the cord twist center O, they act as a cushioning material, so that the deformation of the contact portions of the strands 3b that are in angular contact can be alleviated. Therefore, since the buckling / flattening that occurs at the twisting center O is reduced and the occurrence of cracks in the filaments in the organic fiber filament bundle f is suppressed, the filament fibrillation is combined with the crack prevention. It is suppressed, the fatigue strength of the reinforcing cord 3A is improved, and it becomes possible to maintain a longer life.

The tensile strength of the reinforcing cord 3A is 10 g.
/ D or more is required. Below 10 g / d,
It is virtually impossible to obtain a high tension conveyor belt. That is, if the tensile strength is low, it is necessary to increase the number of cords to be driven in order to obtain a high-strength conveyor belt, which significantly deteriorates the belt manufacturing productivity and the endless work efficiency. Also, finger splicing is virtually impossible.

Furthermore, if the amount of cord driven in is large, the advantage of lightness cannot be enjoyed, and it becomes substantially impossible to provide a lightweight and high-strength conveyor belt. Therefore, the tensile strength of the organic fiber used for the cord is required to be 15 g / d or more. It is generally known that the strength decreases when the organic fibers are twisted together. Even when the structure of the present invention is used, when the organic fiber having a tensile strength of less than 15 g / d is used, the tensile strength of the reinforcing cord is 10 g. It is practically impossible to make it / d or more.

Organic fibers having a tensile strength of 15 g / d or more include aramid fibers, vinylon fibers, poly-p-phenylenebenzbisoxazole fibers, poly-p-phenylenebenzbisthiazole fibers, polyarylate fibers, and ultrahigh molecular weight polyethylene fibers. Etc. are raised. In order to further increase the tensile strength of the reinforcing cord 3A, the organic fiber to be used preferably has a tensile strength of 20 g / d or more.

The diameter of the reinforcing cord 3A is 2 mm.
When the tensile strength is less than 1,000 g / d, even if the tensile strength is 10 g / d or more, the tensile strength per wire is less than 1000 Kgf, and sufficient tensile strength cannot be obtained.
In order to manufacture a conveyor belt having a tensile strength of f / cm or more, many cords must be embedded. Further, the endless processing of the joint becomes extremely complicated, which significantly deteriorates the productivity. Therefore, it is necessary to make it 2 mm or more. When the diameter exceeds 15 mm, it is possible to obtain high tensile strength, but it is practically impossible to sufficiently secure the joining strength at the belt endless portion corresponding to the strength, and the belt durability is deteriorated. At the same time, the thickness of the conveyor belt is increased due to the increase in the code diameter, and the advantage of lightness is reduced. Furthermore, the code diameter is 15 mm
When it exceeds the above range, the deformation on the guide pulley for driving the vehicle during traveling of the belt becomes large, so that the fatigue resistance also decreases.

The thickness of the core yarn 10 needs to be 1 to 15% of the total number of denier (excluding the core yarn) of the reinforcing cord 3A. If it is less than 1%, it is not possible to exert a sufficient function as a cushioning material. If it exceeds 15%, the diameter of the reinforcing cord 3A becomes too thick, the thickness of the conveyor belt 1 increases, and the core yarn 10 easily sticks out from the cord twist center N to the outside of the cord. Therefore, the uniformity of the reinforcing cord 3A is deteriorated and the strength is likely to be reduced. More preferably, it should be 10% or less.

The organic fiber filament bundle h used for the core yarn 10 is not particularly limited as long as it has a greater elongation than the organic fiber filament bundle f forming the strand 3b, and a conventionally known one is used. Although possible, it is preferably constructed from at least one of nylon or polyester fibers. The core thread 10 is
Since it extends substantially straight in the longitudinal direction at the center of the reinforcing cord 3A, the strand breaks when a fiber material having a smaller elongation than the organic fiber filament bundle f forming the strand 3b is used. It breaks before it, and the function as a cushioning material is impaired.

The core yarn 10 is preferably formed by collecting a plurality of organic fiber filament bundles h. Preferably, as shown in FIG. 5, the filaments h'are made of strands 3b.
It is preferable to orient the organic fiber filament bundle f that composes the filament f ′ in the range of ± 20 ° with respect to the orientation direction. When the orientation angle exceeds ± 20 °, tension is applied, and when the filaments f ′ and h ′ in the organic fiber filament bundles f and h come into strong contact with each other, point contact occurs and the stress is locally concentrated. As a result, the contact portion is more likely to be damaged and the fatigue durability is reduced. More preferably, the orientation angle θ is within ± 10 °.

The twisting coefficient K of the reinforcing cord 3A is preferably in the range of 500 to 1500. However, K = T · D ^1/2 (T: number of times of twisting [time / 10c
m], D: total denier number [d] of the reinforcing cord 3A [however, denier of the core yarn is not included]). When the twisting coefficient K is less than 500, the tensile strength of the reinforcing cord 3A is improved, but the fatigue resistance is lowered and the durability of the conveyor belt 1 is lowered, and when it exceeds 1500, the reinforcing cord is increased. Both the tensile strength and fatigue strength of 3A tend to decrease.

The number of compound yarns of the yarn 3a (one yarn 3
Organic fiber filament bundles f used to form a
Number of. Usually, the fibers are manufactured as an organic fiber filament bundle f composed of a bundle of many filaments. [For example, aramid fiber is supplied as an organic fiber filament bundle f of 1500d consisting of a bundle of 1000 filaments] When a plurality of these organic fiber filament bundles f are bundled, the number of the bundled organic fiber filament bundles f It is desirable that the number of yarns is less than the number of combined yarns of the strands 3b (the total number of yarns 3a used to form one strand 3b), which further increases the tensile strength of the reinforcing cord 3A. Therefore, the durability of the conveyor belt 1 can be further improved.

Further, it is more preferable that the number of twisted strands 3b forming the reinforcing cord 3A is three. In the case of four or more strands, not only the productivity of twisting is poor, but also when a tension is applied, the angle of the contact portion of the strand 3b at the cord twisting center O becomes more acute and the bending of the filaments occurs. Is more likely to occur and the fatigue strength is reduced. Further, in the case of two cords, not only the shape retention of the cord is deteriorated, but also the handleability is deteriorated, and when tension is applied, the reinforcing cord 3A is easily flattened and the contact area between the strands 3b is increased. Therefore, fatigue resistance is reduced. In the case of one, it is practically 1
As a result of stepwise twisting, there is no shape retention and the tensile strength and fatigue resistance are extremely poor.

Further, the organic fiber filament bundle f (filament means an extremely thin monofilament in this bundle), the twisted type of the yarn 3a and the strand 3b, is a plurality of organic fiber filament bundles f. Collect and twist in the same direction to form yarn 3a.
a is twisted in the same direction as the organic fiber filament bundle or in the opposite direction to form a strand 3b, and this strand 3b is twisted in the opposite direction to the twisted direction of the yarn 3a and twisted in plural, and the lower twist It is possible to form the reinforcing cord 3A having a three-stage twist structure of middle twist and upper twist.
That is, the following four combinations are possible as the combinations of the lower twist, the middle twist, and the upper twist. S
There are four types: / S / Z, S / Z / S, Z / Z / S, Z / S / Z. In addition, a reinforcing cord embedded in the belt body 2
It is preferable that the twisting directions of the cords 3A are opposite to each other between the adjacent reinforcing cords 3A, so that the untwisting torque can be balanced and the conveyor belt 1 meanders. It is possible to prevent the occurrence of curling and curling (twisting) and improve the straightness of the conveyor belt.

The reinforcing cords 3A are preferably buried so that both side portions of the belt main body 2 are denser than the central portion of the belt main body 2 so that tear resistance of both side portions of the conveyor belt 1 can be improved. As a result, the resistance to external damage due to biting or the like can be increased. Further, in another embodiment, a bundle of organic fiber filaments f forming the reinforcing cord, or a yarn 3a formed by twisting a plurality of the bundles of organic fiber filaments f, or a plurality of yarns 3a are formed. At least one of the strands 3b formed by main twisting is configured by being coated with an adhesive layer containing rubber latex in advance before being twisted into the reinforcing cord 3A.

That is, before the organic fiber filament bundle f forming the reinforcing cord 3A is formed on the yarn 3a, it is pretreated with an adhesive containing a rubber latex capable of forming a film and the surface is coated with the adhesive. , Or organic fiber filament bundle f
Before the strand 3b is formed by twisting a large number of twisted yarns 3a, the surface is previously treated with an adhesive containing a rubber latex capable of forming a film, or the yarns 3a are twisted in plural. Before the strands 3b formed together are formed on the reinforcing cord 3A, the strands 3b are pretreated with an adhesive containing a rubber latex capable of forming a film, and the surface is coated with the adhesive. If the surface protective coating is previously formed with the adhesive containing the rubber latex before being twisted on the reinforcing cord 3A, the strands 3 near the center N of the reinforcing cord 3A are formed.
Even if the filament f'is cracked at the contact portion of b, the fibrillation of the filament f'due to the friction between the strands 3b is suppressed by the protective coating, so that the life of the conveyor belt can be further extended. It will be possible. Further, even if the filament f ′ is damaged due to friction with the core yarn, the extent of the damage is small and the life of the conveyor belt can be further extended.

Here, the rubber latex is not particularly limited, but vinyl pyridine / styrene / butadiene copolymer rubber latex, styrene / butadiene copolymer rubber latex, butadiene rubber latex, chloroprene rubber latex, acrylonitrile / butadiene copolymer rubber. Latex or the like is used. In addition to the rubber latex, it is also possible to mix and use an adhesive such as a resorcin / formaldehyde initial condensate, an epoxy resin, or an isocyanate.

As a method of forming a coating film with an adhesive containing rubber latex in advance before twisting it on the reinforcing cord 3A, it is preferable to perform it at the stage of the strand 3b from the viewpoint of productivity. Organic fiber filament bundle f or yarn
This is because the processing may be performed at the stage 3a, but since the number of processed lines increases, the complexity and efficiency decrease. Also, for example, the strand 3b is formed after the coating is formed in the yarn 3a stage.
The coating may be formed again by treatment at the stage, but from the viewpoint of efficiency, the treatment at the stage of the strand 3b is preferable. In any case, it is preferable from the standpoint of durability that the treatment is performed before the twisting of the reinforcing cord 3A.

A protective film containing a similar rubber latex may be formed in advance before the core yarn 10 is also inserted into the twist center of the reinforcing cord 3A. Hereinafter, examples of the present invention will be described more specifically. 1. As an organic fiber filament bundle forming a reinforcing cord, 1500d (consisting of 1000 filaments) raw yarn of aramid fiber (Technora [manufactured by Teijin Ltd.]) having a tensile strength of 28g / d is used and shown in Table 1. A reinforcing cord having a structure was prepared and embedded in rubber in parallel to manufacture a conveyor belt. The conveyor belt has a peripheral length of 8 m, a width of 50 cm, and a thickness of 16 mm, and the conveyor belt of the present invention (Example 1)
The comparative conveyor belts (Comparative Examples 1 to 3) were manufactured under the same conditions except for the reinforcing cord used.

As the core yarn of the reinforcing cord used in the conveyor belt of the present invention, a 1500-d yarn of polyester fiber filament bundle was used and 4 of these yarns were bundled.
It is used as a 500d / 4 yarn. Further, the total number of denier of the core yarn is 4.8% of the total number of denier of the reinforcing cord. Further, the orientation angle of the filament of the core yarn with respect to the orientation direction of the fiber filaments forming the strand of the reinforcing cord was 0 °, and the twisting coefficient K of the reinforcing cord was 1000.

The reinforcing cords are embedded in rubber.
Before heat treatment, soak in water solution of water-soluble epoxy resin and dry
In addition, the initial condensation of resorcin-formaldehyde
It is dipped in a mixed solution of the substance and rubber latex and dried and heat treated.
However, a material having adhesiveness with rubber was used. Each of these
Durability of the test conveyor belt under the measurement conditions shown below
When a sex evaluation test was conducted, the results shown in Table 1 were obtained. Tensile strength From each new conveyor belt to JIS K6369 (Steel
-Rubbed conveyor rubber belt)
Cut the sample from a position 50 mm or more away from the end
A sample for tensile test was prepared.durability Each conveyor belt t has a bell as shown in FIG.
Of the pulleys 20 and 21 whose diameter is 600 mm
Installed between the belts, tension of 250 kgf per 1 cm of belt width
5 million times at a running speed of 150 m / min.
I let you. After running, test for tensile test in the same manner as above.
Sample, measure the tensile strength, and check the tensile strength when new.
To obtain the retention rate (%) of tensile strength after running, measure the durability
I took it. The greater the strength retention rate, the more durable the belt.
Show that you are excellent.

[0036]

[Table 1] Further, the organic fiber and the conveyor belt size are the same as those described above, and in the conveyor belt of the present invention, the denier number of the core yarn is changed while the structure of the reinforcing cord is the same, and the total denier of the reinforcing cord is changed. Conveyor belts of the present invention (Examples 2 to 5) in which the ratio% of the number of denier of the core yarn to the number of reels was changed as shown in Table 2 and comparative conveyor belts (Comparative examples 4 to 5).
And manufactured. The strength retention of these conveyor belts after the durability test was measured in the same manner as above.

[0037]

[Table 2] Further, the organic fiber and the conveyor belt size were set to the same as in Example 1 above, and in the conveyor belt of Example 1 of the present invention, only the twisting coefficient K was changed, and the tensile strength at the time of new article and the belt durability test were similarly performed. The strength retention rate of was determined. The results are shown in Table 3.

[0038]

[Table 3] Further, in the conveyor belt of Example 1 in Table 1, the test conveyor in which the orientation angle θ with respect to the fiber filament forming the strand of the fiber filament of the core yarn inserted in the center of the reinforcing cord was changed as shown in Table 4. Belts (Test Examples 1 to 7) were produced. When each of these test conveyor belts was subjected to a durability evaluation test under the measurement conditions shown above, the results shown in Table 4 were obtained.

[0039]

[Table 4] Further, in the conveyor belt of the present invention shown in Table 1, the reinforcing cords have the same structure, and the reinforcing cords are treated at the strand stage with an adhesive containing rubber latex to form an adhesive coating containing rubber latex on the surface of the strands. -A twisted cord was used.

That is, four original yarns of aramid 1500d (1000 filaments) are aligned and a ply-twist is added, and then 10 plies of 1500d / 4 ply-twisted yarns (Yarn 3a) are further combined and a middle twist is added. Strands are formed and vinyl pyridine / styrene / butadiene copolymer rubber latex (Nipol manufactured by Nippon Zeon Co., Ltd.)
2518FS) and epoxy resin (Denako made by Nagase Kasei Co., Ltd.
-LE EX313) and blocked isocyanate (Daiichi Kogyo Seiyaku Co., Ltd.)
Elastron BN69) manufactured by Elastron Co., Ltd. was treated with an adhesive dissolved in water so that the solid content ratio was 3: 1: 1, and dry heat treatment was applied. After this, core yarn polyester fiber is made by using the three treated strands.
1500d / 4 was inserted at the center of twisting, and a twisting reinforcing cord was similarly obtained.

Also, a core yarn polyester fiber 1500d / 4 was twisted using a strand similarly treated with an aqueous solution of a rubber latex-free epoxy resin and a blocked isocyanate in a solid content ratio of 1: 1. It was inserted in the center to make a reinforcing cord. The amount of adhesive adhered to the strands used for these reinforcing cords was 5% by weight for the former and 2% by weight for the latter.
Is. These reinforcing cords were further immersed in a mixed solution of resorcin-formaldehyde precondensate and rubber latex, and dried and heat-treated to impart adhesiveness to rubber. Durability was similarly measured using a conveyor belt in which these reinforcing cords were embedded. The results are shown in Table 5.

[0042]

[Table 5]

As is clear from Tables 1 to 5, the reinforcing cord of the reinforcing layer embedded in the belt body is 15 g / d.
A plurality of organic fiber filament bundles having the above tensile strength are collected to form a twisted yarn, a plurality of these yarns are twisted together to form a strand, and a plurality of these strands are twisted together , Middle twist, upper twist 3
It has a multi-stage twist structure, and the total number of denier of the reinforcement cord is 1 to 1 at the center of the twist of the reinforcement cord.
A book in which a core yarn having a denier number of 5% is inserted, and the core yarn is composed of a yarn made of an organic fiber having a greater elongation than an organic fiber filament bundle forming the reinforcing cord. It can be seen that the conveyor belt of the invention not only gives a high tensile strength but also exhibits excellent durability, as compared with the conveyor belt using the reinforcing cord having the other cord-shaped structure of the comparative example.

Further, the organic fiber filaments constituting the core yarn inserted in the center of twisting of the reinforcing cord of the present invention are ± 20 ° with respect to the direction of the organic fiber filaments forming the reinforcing cord. It can be seen that orientation within the range is more preferable in terms of durability. Further, it is found that the twisting coefficient K of the reinforcing cord of the present invention is preferably in the range of 500 to 1500 from the viewpoint of durability and tensile strength.

Further, before forming the reinforcing cord of the present invention, a bundle of organic fiber filaments or a yarn formed by twisting a plurality of the bundles of organic fiber filaments, or
At least one of the strands formed by twisting a plurality of yarns is previously coated with an adhesive layer containing rubber latex before being twisted into a reinforcing cord, in order to improve durability. I know what I like.

[0046]

As described above, according to the present invention, the tensile strength extending along the longitudinal direction of the reinforcing layer embedded in the belt body is 1
A reinforcing cord having a tensile strength of 10 g / d or more and a diameter of 2 to 15 mm, which is formed by twisting 5 g / d or more organic fiber filament bundles, is twisted to form a yarn. A plurality of these yarns are twisted together to form a land, and a plurality of these strands are twisted together to form a three-stage twist structure of lower twist, middle twist, and upper twist, and also twisting of the reinforcing cord. A core yarn having a denier number of 1 to 15% of the total denier number of the reinforcing cord is inserted into the central portion, and the core yarn is inserted into the reinforcing cord.
Since it is made up of yarns made of organic fiber that has a greater elongation than the organic fiber filament bundle that forms the cord,
It is lightweight, has high tensile strength, has no rust and does not have to be discarded, and is excellent in durability. In addition, fatigue strength can be increased and the life of the conveyor belt can be kept longer.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view of a main part of a conveyor belt of the present invention with a part cut away.

2A is an enlarged cross-sectional view of the reinforcing cord shown in FIG. In addition, (b) to (d) are enlarged cross-sectional views showing a reinforcing cord of a comparative example, and (b) 'to (d)' are respective cross-sectional views.

FIG. 3 is an explanatory view showing a state before and after tension is applied to the reinforcing cord (3A) of FIG. 2 when a core yarn is not provided, (a) is a cross-sectional view before tension is applied, (B)
[Fig. 6] is a cross-sectional view after tension is applied.

FIG. 4 is a cross-sectional explanatory diagram when tension is applied to the reinforcing cord of FIG.

FIG. 5 is an explanatory diagram showing the orientation angle of the filament of the core yarn.

FIG. 6 is a schematic explanatory view of a belt running tester.

[Explanation of symbols]

 1 Conveyor Belt 2 Belt Main Body 3 Reinforcing Layer 3A Reinforcing Cord 3a Yarn 3b Strand 10 Core Yarn N Center Part f, h Organic Fiber Filament Bundle f'Filament θ Orientation Angle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshiyuki Yamamoto, No. 2 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Factory (72) Inventor, Yoichi Suto 1-1 Nakamura, Toyooka-cho, Gamagori-shi, Aichi Made in Tokyo Tuna Fiber Rope Co., Ltd. (72) Inventor Takayuki Nagafuku 1-1 Nakamura, Toyooka-cho, Gamagori-shi, Aichi Tokyo Tuna Rope Co., Ltd.

Claims (6)

[Claims] 1. A tensile strength 10 comprising a belt-shaped belt main body, and an organic fiber filament bundle having a tensile strength of 15 g / d or more twisted in the belt main body along the longitudinal direction thereof.
In a conveyor belt in which a plurality of reinforcing cords having a diameter of 2 to 15 mm or more and having a diameter of 2 to 15 mm are embedded substantially parallel to each other in a width direction of the belt main body, the reinforcing cords include a plurality of organic fiber filament bundles. A main twist is formed into a yarn, a plurality of these yarns are twisted together to form a strand, and a plurality of these strands are twisted together to form a three-stage twist structure of lower twist, middle twist, and upper twist. At the same time, a core yarn having a denier number of 1 to 15% of the total denier number of the reinforcing cord is inserted into the twisted central portion of the reinforcing cord, and the core yarn is attached to the reinforcing cord. A conveyor belt characterized in that it is composed of yarns made of organic fibers having a greater elongation than the organic fiber filament bundles forming the cords. 2. The core yarn is constituted by collecting a bundle of organic fiber filaments, and the organic fiber filaments are oriented with respect to the orientation direction of the organic fiber filaments forming the reinforcing cord.
The conveyor belt according to claim 1, oriented in a range of ± 20 °. 3. The organic fiber filament bundle of the core yarn,
The conveyor belt according to claim 1 or 2, which is at least one of nylon fiber or polyester fiber. 4. The twisting coefficient of the reinforcing cord is K, the twisting number is T (times / 10 cm), and the total denier number of the reinforcing cord is D.
4. The conveyor belt according to claim 1, wherein the upper twist coefficient K represented by K = T · D ^1/2 is 500 to 1500. 5. The conveyor belt according to claim 1, wherein the reinforcing cord has a three-strand structure in which three strands are twisted together. 6. At least an organic fiber filament bundle forming the reinforcing cord, a yarn obtained by twisting a plurality of the organic fiber filament bundles, or a strand formed by twisting a plurality of yarns. 6. The conveyor belt according to claim 1, wherein any one of them is coated with an adhesive layer containing rubber latex before being twisted with the reinforcing cord.