JPH0724995U - Rubber product reinforcement - Google Patents

Abstract

(57) [Summary] [Purpose] It has high elongation and small elongation under low load, has excellent shock absorption and fatigue resistance, is lightweight, and has excellent adhesiveness with rubber. To provide a good and inexpensive rubber product reinforcing material. [Structure] A rubber product reinforcing material composed of a single steel filament having a wire diameter d of 0.28 to 0.50 mm,
A steel wire having a small spiral habit over its length is provided with a relatively large corrugated or spiral undulation that is different from the above habit, and has an elongation at break of 4% or more and a 10 kg tensile load. A rubber product reinforcing material having a time elongation of 1% or less is constituted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rubber product reinforcing material used for reinforcing rubber products such as automobile tires and conveyor belts.

[0002]

[Prior art]

 Conventionally, as this kind of reinforcing material, a twisted steel wire called a so-called steel cord 10 in which a plurality of thin steel filaments are densely twisted is used as shown in FIG. Generally, the steel cord 10 is obtained by repeatedly performing heat treatment such as lead patenting and wire drawing on a steel wire rod, followed by brass plating and wire drawing to a predetermined wire diameter to obtain a filament 11. Next, the filaments 11 are manufactured by twisting a plurality of them.

By the way, an essential requirement for a rubber product reinforcing material, in particular, a reinforcing material for tires and conveyor belts is to have required strength and excellent flexibility. In the steel cord 10, the filament 11 is superior in strength to fiber filaments such as nylon and polyester, but is inferior in flexibility. Therefore, it is attempted to twist plural filaments together to improve flexibility. To do. For this reason, there is a problem that a twisting process is required, and it cannot be easily and inexpensively manufactured.

Further, in the steel cord 10, since the filaments 11 are closely contacted and twisted together, the rubber does not enter the hollow portion D at the center of the cord at the time of molding a rubber product, and is continuous in the longitudinal direction of the cord. This hollow portion D exists. Therefore, in the rubber product using the steel cord 10 described above, the adhesion between the rubber and the cord is considered only at the outer peripheral portion of the cord, so that the rubber and the cord are easily separated from each other, which is a so-called separation phenomenon, and the filament is easily produced. Fretting wear between them is also likely to occur. Moreover, since the cavity D exists, the water permeated from the outside reaches the cavity D and propagates in the longitudinal direction of the cord to generate rust. Therefore, there is a problem that the life of the rubber product is shortened.

Further, when a tire is mounted on a small stone, a curb, or the like, and when a heavy object is dropped on a conveyor belt, a steel cord, which is a reinforcing material of the tire, may be broken. As a reinforcing material for various kinds of rubber products, a reinforcing material having high elongation and excellent impact absorption resistance is desired.

In view of the above circumstances, at present, a rubber having a single filament structure which can be manufactured at low cost without a twisting process, has good adhesiveness to rubber, has high elongation, and is excellent in flexibility. Practical application of product reinforcement is considered.

[0007]

[Problems to be solved by the device]

 As a reinforcing material for a rubber product having a single-filament structure, for example, JP-A-48-63961 discloses a corrugated filament, and JP-A-50-43359 discloses a helical filament. Each of them is disclosed.

In the reinforcing materials disclosed in the above-mentioned publications, which have been proposed above, the twisting step is omitted by using a single filament structure, and the adhesiveness with rubber is excellent, and the corrugated shape is obtained. Alternatively, it is possible to increase the elongation at break to the extent equivalent to that of a fiber by processing and shaping it in a spiral shape, and improve the flexibility.

However, any of the above-mentioned proposed reinforcing materials has a problem in terms of elongation characteristics against load, and has not been put into practical use yet at present. That is, the above-mentioned reinforcing material has a very large elongation at break by imparting an excessive wavy or spiral habit to the filament. Therefore, when a tensile load is applied, this reinforcing material shows a very large elongation under a low load due to the characteristic that an excessive wavy or spiral habit of returning to its original state, and the primary elastic limit The bending point exists at the time of low load. By the way, generally, when a load equal to or higher than the first elastic limit is applied, the original stern shape is not restored, and a permanent strain is generated.

Therefore, when the above reinforcing material is used for a rubber product, for example, a belt portion of a tire, the ground surface is not flat or the air pressure is reduced, so that the belt portion is loaded with a load higher than the primary elastic limit. If so, permanent deformation occurs in the reinforcing material, which may reduce fatigue resistance, cause a separate phenomenon, and sometimes deform the tire.

The present invention has been made in view of the above problems, and has elongation characteristics such as high elongation and small elongation at low load, excellent shock absorption resistance, and fatigue resistance. An object of the present invention is to provide a rubber product reinforcing material which has a low weight, is excellent in adhesiveness with rubber, and is inexpensive.

[0012]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present inventor devises the shape of the molding habit by taking advantage of the single filament structure reinforcing material that is lightweight, has good adhesiveness to rubber, and can be obtained at low cost. Based on this knowledge, we have devised the present invention based on this knowledge.

That is, the rubber product reinforcing material of the present invention is a rubber product reinforcing material composed of a single steel filament having a wire diameter d of 0.28 to 0.50 mm, and the steel filament extends in the longitudinal direction. In addition to having a small spiral habit, it also has a relatively large wavy or spiral undulation that is different from the above habit, and has an elongation at break of 4% or more and an elongation at 10 kg tensile load. It is characterized by being less than 1%.

In the rubber product reinforcing material of the present invention, in the above configuration, the eccentric shape has an eccentric outer diameter of H₁ , Habit pitch P₁ And then H₁ = 1.04d to 1.72d, P₁ = 4d to 18d, H₁ / P₁ = 0.05 to 0.3, and the waviness shape has a waviness diameter of H₂ , Pitch of undulation₂ And then H₂ = 1.5H₁ ~ 3H ₁ , P₂ = 2P₁ -10P₁ The structure satisfies the relationship.

By the way, the reason for limiting each numerical value in the above configuration is as follows. The filament wire diameter d must be at least 0.28 mm to ensure the required strength. However, if the diameter is too large, not only the fatigue property decreases but also the weight of the rubber product becomes heavy, so the upper limit was made 0.50 mm.

The habit outer diameter H ₁ and the habit pitch P ₁ , which are the requirements for determining the habit shape, are interrelated in the elongation characteristics of the reinforcing material. H ₁ = 1.04d to 1.72d is because when it is smaller than 1.04d, it has a tradeoff with P ₁ , but the elongation property is similar to that of a straight filament and the flexibility is poor. If it is larger than 1.72 d, the elongation under a low load is large, which causes the various problems described above, and the object of the present invention cannot be achieved. The reason why P ₁ = 4d to 18d is that if it is smaller than 4d, it is difficult to manufacture, and excessive plastic deformation is given during squeezing, resulting in a marked decrease in fatigue resistance. If it is too large, there is a trade-off with d, but the elongation property is similar to that of a straight filament, resulting in poor flexibility, making it unsuitable as a reinforcing material for rubber products. The larger H ₁ / P ₁ gives the filament a higher elongation. At least 0.05 is required to give flexibility, but if it is too large, the elongation at low load becomes too large, so the upper limit was made 0.3.

The undulation diameter H ₂ and the undulation pitch P ₂ , which are the requirements for determining the undulation shape, are also interrelated in the elongation characteristics of the reinforcing material. The reason why H ₂ = 1.5H _{1 to} 3H ₁ is that if it is smaller than 1.5H ₁ , there is a tradeoff with P ₂ , but the filament cannot be given a high elongation, so the shock absorption resistance is increased. On the other hand, if it is larger than 3H ₁ , the elongation under a low load becomes too large. P ₂ = 2P _{1 to} 10P ₁ is set because when it is smaller than 2P ₁ , the elongation under a low load becomes too large, and when it is larger than 10P ₁ , there is a tradeoff with H ₂ , but the filament has Because it cannot give high elongation.

The elongation at break is required to be 4% or more in order to obtain excellent impact absorption resistance, but if the elongation at low load is too large, the effect cannot be expected and the fatigue resistance is deteriorated. Therefore, it is necessary to suppress the elongation at 10 kg tensile load to 1% or less.

[0019]

[Action]

 The rubber product reinforcing material of the present invention has a small spiral shape and a relatively large swell different from the squeezing shape, instead of the conventional oversizing of one type. The seeds are typed together. For this reason, the substantially spiral habit is smaller than the conventional imprinted shape, and is not easily extended by a low load. In the case of using only the habit, the elongation at break cannot be obtained sufficiently, but since the undulation is used in addition to this, sufficient elongation can be obtained. Therefore, in the rubber product reinforcing material of the present invention, due to the presence of the two types of molding, the elongation characteristics are complicatedly mixed, and the elongation characteristics such as high elongation and small elongation under low load are provided. Will be done.

[0020]

【Example】

An embodiment of the present invention will be described below with reference to the drawings. A carbon steel wire with a high carbon content of 0.85 wt% was repeatedly heat treated and drawn, then brass plated and drawn with multiple drawing dies to achieve a surface reduction rate of 97.6%. Then, a steel filament having a wire diameter of 0.38 mm was obtained. Next, this filament is provided with a substantially spiral habit with a habit pitch P ₁ = 2.6 mm and a habit outer diameter H ₁ = 0.48 mm, and a undulation pitch P ₂ = 13 mm and a undulation diameter H ₂ = 0. A spiral waviness of 0.96 mm was applied to obtain a rubber product reinforcing material 1 shown in FIGS. The tensile strength of this reinforcing material was 330 kgf / mm ² , the elongation at break was 5.8%, and the elongation at 10 kg tensile load was 0.72%.

By the way, the substantially spiral or spiral waviness of the filament can be obtained by passing the filament between the peculiar pins provided in the twisting machine and the small-diameter rollers arranged in a zigzag pattern thereafter. Can be easily applied. It can also be carried out by engaging the filament in a gear or the like and twisting the filament. In the former case, the pitches P ₁ , P ₂ and the diameters H ₁ , H ₂ of the peculiarity and waviness can be adjusted to the latter by adjusting the intervals between pins and rollers, the number of rotations of the twisting machine, etc. In this case, the desired value can be set by adjusting the shape of the gear and the number of twists of the filament.

Next, a rubber product reinforcing material having a single filament structure with a wire diameter of 0.38 mm and made of high carbon steel having a carbon content of 0.85 wt% was prepared with the constitution shown in Table 1, and each of them was prepared. The elongation at break, the elongation at 10 kg load, the compression rigidity and the fatigue resistance were evaluated. The results are shown in the table.

[0023]

[Table 1]

In this evaluation, as shown in FIG. 4, the compressive rigidity was measured by a three-point bending test by measuring the load G at the time of pressing 5 mm in the span L = 20 mm of the test piece 12, and comparing it with No. 1 of the conventional example. 1 was set as 100 and displayed as an index. As the test piece 12, a rubber sheet having a thickness of 4 mm, a width of 15 mm, and a length of 100 mm, which was prepared by arranging five reinforcing materials in a horizontal row and embedding it in rubber, was used.

The fatigue resistance was evaluated by embedding a reinforcing material in a plurality of rubber sheets and using this sheet to determine the number of repetitions until breakage with a three-point pulley bending fatigue tester. 1 was set as 100 and displayed as an index.

In Table 1, No. The reinforcing material of No. 1 is a conventional reinforcing material composed of straight filaments which are not shaped, and has a small elongation at break and lacks flexibility. In addition, No. Reinforcing materials Nos. 2 to 4 are conventional reinforcing materials made of one type of filament, and No. The second and third reinforcing materials have small peculiar shapes and thus have small elongation at break and lack flexibility. No. The reinforcing material of No. 4 has a large elongation at break, but has a large elongation at a low load, and therefore has low rigidity and poor fatigue resistance. No. The reinforcing materials of Nos. 5 and 6 are reinforcing materials composed of two types of typed filaments, but the elongation at break and the elongation at low load are not proper because the curl and waviness are not appropriate.

On the other hand, the reinforcing material of the present invention No. Nos. 7 to 9 have an elongation at break of 4% or more, a small elongation at low load, excellent flexibility, and good fatigue resistance. An evaluation suitable as a reinforcing material was obtained.

[0028]

[Effect of device]

 Since the rubber product reinforcing material of the present invention has a single filament structure, it does not require a twisting process, can be easily and inexpensively manufactured, and has good adhesiveness to rubber. Further, since it has an elongation at break of 4% or more and a small elongation at a low load, it has excellent impact absorption resistance and fatigue resistance. Therefore, for example, when it is used as a tire reinforcing material, it is possible to improve the cut resistance and the riding comfort and to remarkably improve the life of the tire. Further, since the amount of rubber to be covered can be reduced, it is possible to realize the weight saving of the tire required from the viewpoint of energy saving.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a rubber product reinforcing material of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, showing the rubber product reinforcing material of the present invention.

FIG. 3 is a schematic cross-sectional view showing a conventional steel cord.

FIG. 4 is a schematic diagram for explaining a three-point bending test method.

[Explanation of symbols]

 1 Rubber product reinforcement

Claims (2)

[Scope of utility model registration request] 1. A rubber product reinforcing material comprising a single steel filament having a wire diameter d of 0.28 to 0.50 mm, wherein the steel filament has a small spiral habit along its length, and A rubber having a relatively large substantially wavy or substantially spiral undulation different from the above habit, and having an elongation at break of 4% or more and an elongation at 10 kg tensile load of 1% or less. Product reinforcement. 2. The habit shape has a habit outer diameter of H ₁ and a habit pitch of P _1, and H ₁ = 1.04d to 1.72d,
P ₁ = 4d to 18d and H ₁ / P ₁ = 0.05 to 0.3 are satisfied, and the waviness is H ₂ = 1 when the waviness diameter is H ₂ and the waviness pitch is P _2. .5H _{1 to} 3H
_1, according to claim 1 which satisfies P ₂ = 2P ₁ ~10P ₁ relationship
Reinforcement material for rubber products described.