JPH10291618A - Conveyer belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide lightness and durability for a conveyer belt, by providing the conveyer belt with three-twisting structure in which three intermediate-twisting-threads which are produced by placing a specific number of lower-twisting-threads, which is produced by twisting a specific number of organic fiber raw threads with specific tensile strength, at its core part and its side part, and upper-twisting-threads are combined, and by making the structure meet an equation I and its twisting factor meet an equation II. SOLUTION: In a belt body, plural reinforced codes which are produced by twisting organic fiber raw threads with tensile strength over 15 g/d and have tensile strength over 10 g/d and total denier of 800,000-900,000/d are placed along longitudinal direction of the belt. Each reinforced code has three-twisting structure in which three intermediate-twisting-threads which are produced by placing (m) lower-twisting-threads, which are produced by twisting K organic fiber raw threads, at its core part and (n) lower-twisting-threads at its side part, and upper-twisting-threads are combined. The code structure is represented by equation I:3×(m+n)×(1×K), (where, 10>=K>=1, 10>=m>=1, 20>=n>=3, n>m). Its twisting factor is represented by equation II: 2.4>=Km/Kn>=1.2, (where, Km(twisting factor of lower-twisting- threads at the core part)=Tm√Dm, Kn(twisting factor of lower-twisting-threads at the side part)=Tn√Dn, 700>=Kn>=200, Tm, Tn = number of twisting of lower-twisting-threads at the core part and the side part, respectively (times/10 cm), Dm, Dn = denier of lower-twisting- threads at the core part and the side part, respectively (d)).

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 excellent in durability.

[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. Conventionally, as the reinforcing layer, a canvas belt using a woven fabric made of an organic fiber represented by a nylon fiber, a polyester fiber, or the like, and a steel conveyor belt using a steel cord have been known. In general, canvas belts have the advantage of being lighter in weight than steel cord belts, but have a lower tensile strength than steel cord belts, and conveyer belts that require a high tensile strength of 500 kgf / cm or more are required. Not suitable for reinforcement layers. On the other hand, steel cord conveyor belts
Twist a number of steel wires to make the diameter 2mm ~
It has a structure in which a plurality of steel cords having a thickness of about 15 mm and high tensile strength are buried substantially parallel to the longitudinal direction of the conveyor belt without using a weft like a woven fabric. Since a steel cord with high tensile strength is used in this way, and a cord is used as a reinforcing layer,
There is an advantage that a finger splice having high joining efficiency (joining strength) can be performed at the endless joining portion of the conveyor belt, and a conveyor belt that can withstand high tension can be provided.

However, since the steel cord conveyor belt uses steel for its reinforcing layer, it is heavy in weight, and when used in a humid environment or when the rubber is cracked, rust is generated due to water penetration. This causes a problem that adhesive breakage and cord breakage are likely to occur. There is also a problem that the disposal of the used conveyor belt is extremely complicated. Further, with recent environmental problems and deterioration of the economic environment, there is a strong demand for a conveyor belt having a lighter weight, a higher tensile strength, and a longer life.

As a method for solving such a problem, a conveyor belt has recently been developed in which aramid fibers having a high tensile strength among organic fibers are used as a reinforcing layer in the form of a woven fabric. However, a conveyor belt using an aramid woven fabric for the reinforcement layer has a joint strength that is high even when a finger splice structure with the highest endless efficiency is applied to the endless portion (joint portion) because the reinforcement layer has a woven structure. There is a limit, and a material having a tensile strength of about 2000 kgf / cm is a practically usable limit. Further, even if an endless method having extremely high endless efficiency is developed, the high strength inherent in the aramid fiber cannot be sufficiently utilized because the aramid fiber has a woven structure, and the tensile strength is approximately 2000 kgf /. It is practically impossible to produce a durable woven fabric having a length exceeding 1 cm. Furthermore, when a woven structure is used, if notches such as cracks are formed at both ends in the width direction of the conveyor belt, there is a problem that the belt is easily broken due to stress concentration.

Therefore, it is lightweight and 2,000 kgf / cm
It has been desired to develop a new conveyor belt that can be used even in a region where a tensile strength exceeding 10 mm is required.
In response to such a problem, the present inventors have disclosed Japanese Patent Application Laid-Open No. 7-14 / 1995.
No. 4731 discloses a method consisting of priming, medium-twisting, and twisting.
It was proposed to use a step-twisted reinforcing cord for the reinforcing layer of the conveyor belt. According to the present invention, it has become possible to use a conveyor belt having high tension and high fatigue durability, which cannot be achieved by a conventional conveyor belt using an organic fiber fabric as a reinforcing layer. However, it is desired that these conveyor belts have a longer life, and in particular, improvement of the fatigue durability of the reinforcing layer has been a problem.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lightweight, high-tension, rust-free, and complicated disposal.
An object of the present invention is to provide a conveyor belt having excellent durability.

[0007]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, has a tensile strength of 10 g / d obtained by twisting an organic fiber raw yarn having a tensile strength of 15 g / d or more in a belt body in the longitudinal direction of the belt. As described above, the total denier number D is 800,000.
In a conveyor belt in which a plurality of reinforcing cords in a range of d ≧ D ≧ 90000d are buried, the reinforcing cords form knitted yarns by k-plying the organic fiber raw yarns, and the lower twisted yarns are used as cores. A mult-twisted yarn is formed by arranging m yarns and n-wires on the side portions to form a middle twisted yarn. Further, the three middle-twisted yarns are combined with each other and twisted, and the cord structure is as follows (1). ) is a structure of the formula, each of K _m of twist coefficient under twisting the lower twine and a side portion of the core, when the K _n, the twist ratio K _m / K _n is the following equation (2) of the coefficients Is satisfied.

Code structure 3 × (m + n) × (1 × k) (1) where 10 ≧ k ≧ 1, 10 ≧ m ≧ 1, 20 ≧ n ≧ 3,
n> m. Twist coefficient ratio 2.4 ≧ K _m / K _n ≧ 1.2 (2) where K _m = T _m √D _m , K _n = T _n √D _n , 700
≧ K _n ≧ 200 T _m : Number of twists of the lower twist yarn constituting the core (twice / 10 cm) D _m : Denier number of the lower twist yarn constituting the core (d) T _n : Length of the lower twist yarn constituting the side Number of twists (times / 10 cm) D _n : Denier number (d) of the lower twist yarn constituting the side portion.

As the reinforcing layer buried in the longitudinal direction of the belt main body, a reinforcing cord having a specific twist configuration, a specific thickness and a specific tensile strength is obtained by twisting an organic fiber raw yarn having a specific tensile strength. By forming it by using it, it is lightweight, has high tension, and can improve the durability of the conveyor belt, and there is no rust like steel cord, and the used conveyor belt can be disposed of. There is no complication.

In the present invention, it is preferable to embed a reinforcing cord having a twist coefficient K _{M of} medium twist and a twist coefficient K _{U of} upper twist satisfying the following expression. 1400 ≦ K _M ≦ 2000, 0.80 ≦ K _U / K _M ≦
1.10 _{Here, K M = T M √D M} , K U = T U √D U T M: number of twists of medium twist (times / 10cm), D _M: total denier number of medium twist (d) T _U : the number of twists in the twist (twice / 10 cm); D _U : the total denier (d) of the twists.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional perspective view of a main part of a conveyor belt according to the present invention, in which a part of the conveyor belt is cut away.
A reinforcing layer 3 is embedded in a belt body 2 on an endless belt made of a thermosetting resin or the like along the longitudinal direction.

The reinforcing layer 3 has a plurality of reinforcing cords 3A arranged along the longitudinal direction of the belt main body 2, and these reinforcing cords 3A are substantially spaced at predetermined intervals in the width direction of the belt main body 2. They are arranged in parallel. As shown in FIG. 2, the reinforcing cord 3A constituting the reinforcing layer 3 is formed by twisting a plurality of organic fiber raw yarns x having a tensile strength of 15 g / d or more to form a lower twisted yarn 3a. One or more in the part, a plurality of these are arranged in the side part and twisted to form a middle twisted yarn 3b, and furthermore, the middle twisted yarn 3b is twisted three times, and the primary twist is obtained by twisting the organic fiber raw yarn x. Lower twist yarn 3
is a three-stage twisted structure in which a medium twist is formed by twisting a and a medium twist yarn 3b is twisted, and a reinforcing cord 3A is provided.
Has a tensile strength of 10 g / d or more and a total denier of the reinforcing cord of 90,000 to 800,000 d.

FIG. 2 (a) shows that a lower twisted yarn 3a is formed by twisting four organic fiber raw yarns x, and this lower twisted yarn is used as a core in a core portion.
A cord structure of 3 × (1 + 6) × (1 × 4) is formed by forming six twisted middle twisted yarns 3b on the side portions and twisting the three twisted middle twisted yarns 3b. It is an example of a structure. FIG. 2 (b) shows a twisted medium yarn 3b formed by twisting four organic fiber raw yarns x to form a lower twisted yarn 3a, arranging two lower twisted yarns at the core and eight at the side portions and twisting. An example of a cord structure having a 3 × (2 + 8) × (1 × 4) structure, which is formed and further twisted by adding three of the medium twisted yarns 3b, is shown. When these code structures are represented by a general formula, the following formula (1) is obtained.

Cord structure 3 × (m + n) × (1 × k) (1) where 3 is the number of upper-twisted ply yarns, m + n is medium-twisted and has a multi-layer twisted structure, and m of m + n is medium. The number of the lower twisted yarns 3a forming the core of the twisted yarn 3b, n indicates the number of the lower twisted yarns 3a forming the side portions, and these values are 10 ≧ k ≧ 1, 10 ≧ m ≧
1, 20 ≧ n ≧ 3, and the relationship between m and n is n> m.

The core of the middle twist yarn 3b may have a two-layer structure as shown in FIG. Here, as shown in FIG. 3 (b), five organic fiber raw yarns x are twisted to form a lower twist yarn 3a, and two lower twist yarns 3a are arranged in the core inner layer and eight lower twist yarns are arranged in the core outer layer. With a two-layer structure, and a lower twist yarn 3
a are arranged and twisted to form a medium twist yarn 3b,
FIG. 3A shows an example of a three-twisted structure in which three of the medium twisted yarns 3b are combined and twisted. When the core portion has a two-layer structure in this manner, the number m of the lower twisted yarns 3a constituting the core portion in the above formula (1) refers to the number of the lower twisted yarns 3a in the core outer layer. The structure of the cord having a two-layer structure can be represented by the following general formula, where p is the number of lower twisted yarns 3a in the core inner layer.

Code structure 3 × (p + m + n) × (1 × k) where n>m> p, and 3 ≧ p ≧ 0, k, m,
n is the same as above. When the total number of the lower twisted yarns 3a constituting the reinforcing cord 3A is less than 60, the middle twisted yarn 3b has two layers of m + n, and when it is 60 or more, p + m + n.
It is preferable to adopt a configuration.

Here, the raw yarn x constituting the lower twist yarn 3a is
An organic fiber filament bundle consisting of a large number of thin filaments and substantially untwisted, and supplied by a fiber manufacturer. For example, aramid fibers suitable for the present invention are 1000d, 1500d, 3000d as a fiber bundle composed of many thin filaments.
These are referred to as raw yarns.

For example, the reinforcing cord 3 shown in FIG.
A = 3 × (1 + 6) using aramid yarn of 1500d
In the case of a × (1 × 4) structure, four 1500d raw yarns x are combined and twisted, and six lower twisted yarns 3a are arranged around one lower twisted yarn 3a and twisted. The twisted yarn 3b can be obtained by adding three twists of the medium twisted yarns 3b and then twisting them. In addition, the reinforcing cord 3A shown in FIG. 2 (b) is a 3 × (2+
8) In the case of a × (1 × 4) structure, four 1500d raw yarns are combined and ply-twisted, and eight ply-twisted yarns 3a are arranged around the two ply-twisted yarns 3a to perform twisting. In addition, a middle twist yarn 3b can be used, and three of the middle twist yarns 3b can be combined and then twisted to make the middle twist yarn 3b. Further, the reinforcing cord 3A shown in FIG. 3 is a 3 × (2+
8 + 17) × (1 × 5), 150
Five untwisted yarns 3a are arranged around two of these three twisted yarns 3a, and eightteen untwisted yarns 3a are arranged around two of these two twisted yarns 3a. It can be obtained by forming a middle twisted yarn 3b, and further combining three of the medium twisted yarns 3b and twisting them. Medium twist yarn 3b
The reason for disposing the lower twisted yarn 3a in this manner is that if a large number of the lower twisted yarns 3a are simply bundled and twisted to form a medium twisted yarn 3b, the lower twisted yarn 3a causes migration in the medium twisted yarn 3b and the tensile strength utilization rate is reduced. Because it gets worse.

Further, as the lower twist yarn 3a constituting the middle twist yarn 3b shown in FIG. 2, at least two types of lower twist yarn 3an and lower twist yarn 3am having different numbers of twists are used.
Under twisting 3a of the core which is arranged between the inside twist coefficient K _n under twisting 3an sides disposed in the outermost layer of the middle twisting 3b
The twist ratio K _{m of m is such that} the ratio K _m / K _n satisfies the following equation (2). In the structure shown in FIG. 3, the lower twisted yarn 3a constituting the middle twisted yarn 3b of the reinforcing cord 3A is also used.
At least two lower twisted 3an and lower twine 3am of twist number different is used, the core portion disposed twist coefficient K _n under twisting 3an sides disposed in the outermost layer of the middle twisting and on the inner side Ratio K _m / K _n of twist coefficient K _m of lower twist yarn 3am
Satisfy the following expression (2). Incidentally, in the structure shown in FIG. 3, but still is not particularly specified twist factor under twisting 3ap the outermost core portion disposed on the inner side of the lower twisted 3am, about equal to K _m value greater than the K _m It is good to do.

The reason is that the lower twisted yarn 3am arranged inside the middle twisted yarn 3b and the lower twisted yarn 3an arranged outside the middle twisted yarn 3b are arranged inside if the twisting coefficients are equal when tension is applied to the reinforcing cord 3A. This is because tension is applied by the formed lower twist yarn 3am, and if bending is applied by a pulley or the like as a conveyor belt in this state, a load is applied to the inner lower twist yarn 3am and fatigue occurs first. Therefore, by increasing the twisting coefficient of the lower twisted yarn 3am arranged inside from the twisting coefficient of the lower twisted yarn 3an arranged outside,
The tension load can be equalized. Its twist coefficient ratio K _m
/ K _{n is, 2.4 ≧ K m / K n} ≧ 1.2 ··· (2) but is used, more preferably 2.0 ≧ K _m / K _n ≧
1.5. Further, the lower twist coefficient K _n represented by the following formula under twisting 3an disposed outside 700 ≧ K _n ≧ 200
Must be in the range of, more preferably 500 ≧
A range of K _n ≧ 300 is used.

Here, K _m = T _m √D _m , K _n = T _n √
D _n T _m : Number of twists of the lower twist yarn constituting the core (or core outer layer when the core has a plurality of layers) (times / 10 cm) D _m : Core (when the core has a plurality of layers, core It is denier below twisted yarns constituting the side (d): denier lower twisted yarns constituting the outer layer) (d) T _n: number of twists under twisted yarns constituting the sides (times / 10 cm) D _n .

[0022] K _m / K _n fatigue of the lower twisted 3am placed inside as described above is deteriorated in the case of less than 1.2, whereas, if the K _m / K _n exceeds 2.4 , Lower twist yarn 3a
n decreases in strength, and as a result, the strength of the reinforcing cord 3A decreases. When _Kn is less than 200,
Not only does the convergence of the lower twisted yarn 3a decrease and the tensile strength utilization rate deteriorates, but also the fatigue properties and the adhesion to rubber and the like decrease. On the other hand, when it exceeds 700, the convergence is enhanced, but the tensile strength is greatly reduced.

On the other hand, the 3 × 7 × (1 × 4) structure shown in FIG. 4 is based on the structure disclosed in the conventional example (Japanese Patent Laid-Open No. 7-144731), and is shown in FIG. However, the middle twisted yarn 3b has a structure obtained by simply collecting seven lower twisted yarns 3a and twisting them together.
Further, the same number of twists are used for the lower twisted yarn 3a forming the middle twisted yarn 3b. The lower twist yarn 3a is the original yarn x
Are combined and twisted. In the case of such a structure, problems such as code migration as described above occur.

Further, in the present invention, it is more preferable to use a reinforcing cord having a twist coefficient K _M of medium twist and a twist coefficient K _{U of} upper twist satisfying the following expression. 1400 ≦ K _M ≦ 2000, 0.80 ≦ K _U / K _M ≦
1.10 Here, K _M = T _M √D _M , K _U = T _U中 D _U T _M : the number of twists of the medium twist (twice / 10 cm), D _M : the total denier number of the medium twist yarn (d) T _U : the number of twists of the twist (twice / 10 cm); D _U : the total denier (d) of the twisted yarn.

In general, when the twist coefficient is small, the fatigue strength is reduced, but the initial tensile strength is increased. On the other hand, when the twist coefficient is large, the fatigue resistance is improved, but the tensile strength is reduced. The present inventors at the twist structure, various investigated results the relationship between the K _M and K _U, In such a reinforcement cord, the tensile strength and fatigue resistance over a twist coefficient dependent twisting in the It found different things dependent twist coefficient twisting, as a high-tension conveyor belt, it is important to set the K _M and K _U within the above range to satisfy both the prescribed tensile strength and fatigue resistance I found something.

The tensile strength of the reinforcing cord 3A is 10 g /
It is necessary to be at least d. If it is less than 10 g / d, it is practically impossible to obtain a high tension conveyor belt. That is, in order to obtain a high tension conveyor belt with a low tensile strength, it is necessary to extremely increase the number of cords to be driven, which deteriorates the productivity of the belt production and significantly impairs the endless work efficiency. Also, finger splicing becomes substantially impossible. Furthermore, if the cord driving amount is large, the advantage of lightness cannot be enjoyed, and it becomes substantially impossible to provide a lightweight and high-tension conveyor belt. For this reason, the organic fiber raw yarn used in the cord needs to have a tensile strength of 15 g / d or more.

It is generally known that the strength is reduced when the organic fiber yarn is twisted. Even when the structure of the present invention is used, when the organic fiber yarn having a tensile strength of less than 15 g / d is used, the reinforcing cord is not used. It is practically impossible to increase the tensile strength of the steel to 10 g / d or more. Organic fibers used for the yarn having a tensile strength of 15 g / d or more include aramid fiber, vinylon fiber, poly-p-phenylene benzobisoxazole fiber, poly-p-phenylene benzobisthiazole fiber, polyarylate fiber, High molecular weight polyethylene fibers and the like can be mentioned.

In order to further increase the tensile strength of the reinforcing cord 3A, it is preferable that the organic fiber raw yarn used has a tensile strength of 20 g / d or more. The reason why the total denier of the reinforcing cord of the present invention is limited to 90,000 to 800,000d is that the tensile strength is 10% when the thickness of the reinforcing cord 3A is less than 90,000d.
Even if it has a strength of g / d or more, the tensile strength per one piece is less than 1000 kgf, and it is not possible to obtain a sufficient tensile strength, and to manufacture a conveyor belt having a tensile strength of 2000 kgf / cm or more. In this case, a large number of cords must be buried, and the endless processing of the joining portion of the conveyor belt becomes extremely complicated, thereby greatly reducing productivity. Therefore, it is necessary to make it 90,000 d or more. When the thickness exceeds 800,000 d, it is possible to obtain a high tensile strength, but it is practically impossible to secure a sufficient bonding strength at the belt endless portion corresponding to the strength,
As the belt durability decreases, the thickness of the conveyor belt increases due to the increase in the cord diameter, and the advantage of lightness decreases. Further, when the cord thickness exceeds 800,000d, the deformation on the guide pulley for driving the running during belt running becomes large, so that the fatigue resistance also decreases.

In the reinforcing cord 3A, the following four combinations of twist directions in each twisting step are preferable. That is, the direction of the lower twist, the middle twist, and the upper twist is S / S /
Z, S / Z / S, Z / Z / S, and Z / S / Z. At least the twisting directions of the middle twist and the top twist are different from the viewpoint of the form stability and fatigue durability of the reinforcing cord. Is preferred.

The reinforcing cords 3A embedded in the belt body 2 are preferably arranged such that the upper twisting directions of the reinforcing cords 3A are opposite to each other between the adjacent reinforcing cords 3A, thereby balancing the twist release torque. Therefore, the conveyor belt 1 can be prevented from meandering or curling, and the straightness of the conveyor belt can be improved.

The reinforcing cord 3A is preferably embedded so that both sides of the belt main body 2 are denser than the center of the belt main body 2, thereby increasing the tear resistance of both sides of the conveyor belt 1. Thus, the trauma resistance due to biting or the like can be improved. Furthermore, in order to make the present invention more effective, the organic fiber raw yarn x forming the reinforcing cord 3A
Alternatively, the organic fiber raw yarn x is formed by twisting a large number of the organic fiber raw yarns x and then coating the lower twisted yarn 3a with an adhesive layer containing a rubber latex before being twisted into the reinforcing cord 3A. .

That is, before the organic fiber raw yarn x forming the reinforcing cord 3A is formed into the lower twisted yarn 3A, it is pre-treated with an adhesive containing a rubber latex capable of forming a film, and the surface is coated with the adhesive. Before forming a primary twisted yarn obtained by twisting a large number of fibrous yarns x into a medium twisted yarn, the surface is coated 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 formed beforehand with the adhesive containing rubber latex before twisting with the reinforcing cord 3A, the lower twisted yarn 3a and the middle twisted yarn 3b in the reinforcing cord may be subjected to friction at the contact portions of each other. As a result, the fibrillation of fiber filaments generated can be suppressed, and the life of the conveyor belt can be further extended.

The rubber latex is not particularly limited, but includes 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. Also, besides rubber latex, resorcinol-formaldehyde initial condensate,
It is also possible to mix and use adhesives such as epoxy resins and isocyanates.

It is more effective to coat the adhesive with an adhesive layer formed by using an adhesive containing graphite fine particles or molybdenum disulfide fine particles or a mixture of both. As described above, the reinforcing cord 3A is formed by twisting a plurality of middle twisted yarns 3b, and when tension is applied to the reinforcing cord and bending is applied by a guide roll or the like, the middle twisted yarns 3b slightly rub against each other to cause displacement. Occurs. At this time, the fiber filaments are liable to be fibrillated due to friction, and the strength tends to be reduced. By including solid particles of graphite or molybdenum disulfide in the adhesive layer, the frictional resistance is reduced and the fibrillation of the fibers can be further prevented.

The solid fine particles used have a particle size of 1
0 μm or less is preferable, and 1 μm or less is more preferable in terms of lubricity and adhesiveness. The amount of the solid fine particles added to the adhesive layer is preferably 80 parts by weight or less based on 100 parts by weight of the adhesive. If it exceeds 80 parts by weight, the adhesion between the adhesive and the rubber tends to decrease. 10 to 40 parts by weight is more preferable from the viewpoint of frictional resistance and adhesiveness.

[0036]

Example 1 An organic fiber raw yarn forming a reinforcing cord has a tensile strength of 2
8 g / d aramid fiber (Technola [Teijin Co., Ltd.]
1500d (consisting of 1000 filaments)
Using the raw yarn, a reinforcing cord having the structure shown in Table 1 was produced and buried in parallel with rubber to produce each test conveyor belt.
Each of the test conveyor belts has a circumference of 8 m, a width of 50 cm, and a thickness of 16 mm.
The comparative conveyor belt (comparative example) and the conventional conveyor (conventional example) are all manufactured under the same conditions except for the reinforcing cord used. Further, K _m /
K _n is 1.86.

In addition, these reinforcing cords are in the stage of the lower twist yarn,
After immersion drying and heat treatment in a treatment liquid obtained by mixing a water-soluble epoxy resin, rubber latex and blocked isocyanate, and further graphite fine particles, further immersion in a liquid mixture of resorcinol-formaldehyde precondensate and rubber latex, and drying heat treatment, After imparting the adhesiveness with, a twist was applied to form a predetermined twist structure.

Each of the test conveyor belts was evaluated for tensile strength and durability under the following measurement conditions, and the results shown in Table 1 were obtained. Tensile strength JIS K6369 from each new test conveyor belt
In accordance with (Steel Cord Conveyor Rubber Belt), a sample (reinforcement cord) was cut out from a position 50 mm or more from both ends of the belt to prepare a sample for a tensile test, and the tensile strength was measured. Endurance Each test conveyor belt t is connected to a pulley 20, 2 having a diameter of a belt running test machine of 600 mm as schematically shown in FIG.
1 and a tension of 250 kgf per reinforcing cord was applied via the guide 22 and the vehicle was run 5 million times at a running speed of 150 m / min. After traveling, in the same manner as above, a tensile test sample was collected, and the tensile strength was measured.
The retention rate (%) of the tensile strength after running with respect to the new tensile strength was determined and used as a measure of durability. The greater the strength retention, the better the belt durability.

[0039]

[Table 1]

The embodiment is a reinforcing cord twisted according to the present invention. On the other hand, in the comparative example, the twist configuration is the same as the present invention, but the twist coefficient of the lower twist yarn arranged inside the lower twist yarn constituting the middle twist yarn and the twist coefficient of the lower twist yarn arranged outside are the same. is there. Further, in the conventional example, all the lower twisted yarns constituting the middle twisted yarn are twisted with the same twist coefficient, and further, these lower twisted yarns are simply twisted together to form a medium twisted yarn (disclosed in Japanese Patent Application Laid-Open No. 7-144731). Structure).

As is clear from Table 1, the examples of the present invention have almost the same tensile strength as the comparative example, but the strength retention after fatigue is clearly good. In addition, it can be seen that both the tensile strength and the strength retention after fatigue are clearly superior to the conventional example. When the same test was performed by changing the ratio of the twist coefficient K _m and K _n below twisting at the configuration of 3 × Example 2 Example 1 (1 + 6) × ( 1 × 4), Figure 6 The results shown were obtained. Here, K _m was changed _assuming that K _n = 350. The medium twist coefficient and the first twist coefficient are the same as those of the above-mentioned conveyor belt of the present invention.

FIG. 6 shows that when the ratio K _m / K _n is less than 1.2, the retention of fatigue strength deteriorates, and when it exceeds 2.4, the tensile strength decreases. Example 3 In the 3 × (1 + 6) × (1 × 4) configuration of Example 1, the K _m / K _n ratio of the lower twisted yarn is set to 1.86 which is the same as that of the conveyor belt of the present invention, and the twist coefficient K of the medium twist yarn is set. _The evaluation was carried out in the same manner by changing the twisting coefficient K _U of _M and the upper twist. The results are shown in FIG. 7, where the initial tensile strength was 200
Twisted structures that have obtained results of 0 Kgf or more and a strength retention after fatigue of 85% or more are indicated by ○, and twisted structures that do not satisfy any of them are indicated by ●. In addition, x in the figure indicates that the cord was kinked because the twist was too strong at the time of forming the reinforcing cord, and it was substantially difficult to make the cord.

As is apparent from FIG. 7, in order to obtain a result in which the initial tensile strength is 2000 kgf or more and the strength retention after fatigue is 85% or more, the twist coefficient K _M of the middle twist and the twist coefficient of the upper twist are obtained. K _U of 1400 ≦ K _M ≦ 2000, and it is understood that it is preferable in the range of _{0.80 ≦ K U / K M ≦} 1.10.

[0044]

As described above, according to the present invention, the reinforcing layer embedded in the belt body has a tensile strength extending along the longitudinal direction of one.
Twisting a reinforcing cord having a tensile strength of 10 g / d or more and a total denier of 90,000 to 800,000 d by twisting an organic fiber yarn of 5 g / d or more with a specific twist structure and a specific number of twists. By using as a three-strand reinforcing cord consisting of priming, medium-twisting, and ply-twisting, it is lightweight, has high tensile strength, has no rusting and hassle of disposal, and has excellent durability. It becomes possible to provide a conveyor belt.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view of a main part of a conveyor or a belt according to the present invention, in which a part of the belt is cut away.

FIGS. 2A and 2B are enlarged cross-sectional views each showing an example of a reinforcing cord used for the conveyor belt of the present invention.

FIG. 3A is an enlarged cross-sectional view showing another example of a reinforcing cord used in the conveyor belt of the present invention in a state where raw yarns constituting a lower twist yarn are omitted, and FIG. It is an expanded sectional view of the lower twist yarn used.

FIG. 4 is an enlarged sectional view showing an example of a reinforcing cord used for a conventional conveyor belt.

FIG. 5 is a schematic explanatory view of a belt running test machine used in a durability test.

FIG. 6 is a graph showing the relationship between the ratio K _m / K _n of the twist ratio of the core twisted yarn and the side twisted yarn, and the tensile strength and strength retention.

FIG. 7 is a graph showing the relationship between the medium twist coefficient K _M and the twist coefficient K _U , and tensile strength and strength retention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conveyor belt 2 Belt main body 3 Reinforcement layer 3A Reinforcement cord 3a Lower twisted yarn 3am Core lower twisted yarn 3an Side lower twisted yarn 3ap Most cored lower twisted yarn 3b Upper twisted yarn x Organic fiber original yarn

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuto Yanatori 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Works (72) Inventor Yoichi Shuto 1-1 1-1 Nakamura, Gamagori-shi, Aichi, Tokyo (72) Inventor Takayuki Eifuku 1-1, Nakamura, Gamagori-shi, Aichi Prefecture, Tokyo Textile Ropes Co., Ltd.

Claims (2)

[Claims] 1. A tensile strength of 10 g / d or more obtained by twisting an organic fiber yarn having a tensile strength of 15 g / d or more in a belt main body along the longitudinal direction of the belt, and a total denier number D of 80 or more.
In a conveyor belt in which a plurality of reinforcing cords in a range of 0000d ≧ D ≧ 90000d are embedded, the reinforcing cords form knitted yarns by k-knitting the organic fiber raw yarns, and the lower twisted yarns are used as cores. The m-twisted yarn is formed by arranging m yarns and n-side yarns to form a middle twisted yarn, and then twisting the three middle twisted yarns to form a twisted yarn. a structure wherein each K _m of twist coefficient under twisting the lower twine and a side portion of the core, when the K _n, the ratio K _m / K _n of the twist coefficient is the following formula (2) Conveyor belt characterized by satisfaction. 3 × (m + n) × (1 × k) (1) However, 10 ≧ k ≧ 1, 10 ≧ m ≧ 1, 20 ≧ n ≧ 3, n
> M 2.4 ≧ K _m / K _n ≧ 1.2 (2) where K _m = T _m √D _m , K _n = T _n √D _n , 700 ≧
K _n ≧ 200 T _m : number of twists of the lower twist yarn constituting the core portion (twice / 10 cm) D _m : denier number of the lower twist yarn constituting the core portion (d) T _n : twist of the lower twist yarn constituting the side portion Number (times / 10 cm) D _n : Denier number of lower twist yarn constituting side part (d) 2. The conveyor belt according to claim 1, wherein the twist coefficient K _{M of the} middle twist and the twist coefficient K _{U of the} upper twist satisfy the following expression. 1400 ≦ K _M ≦ 2000, 0.80 ≦ K _U / K _M ≦
1.10 _{However, K M = T M √D M} , K U = T U √D U T M: number of twists of medium-twisting (times / 10cm), D _M: the total denier number of medium-twist (d) T _U : Number of twists (twice / 10cm), D _U : Total denier of twists (d)