JPH03297713A - Conveyer belt reinforcing material and conveyer belt - Google Patents

Abstract

PURPOSE:To improve the thermal resistance and the fatigue resistance of rubber material by using a core-sheath type composite fiber which is composed of a core component, consisting of polyethylene-2 and 6-naphthalate, and a sheath component having a main component of polyamide, and in which component weight% and the strength, ductility, initial tensil resistance, and dry heat shrinkage percentage of the fiber are individually specified. CONSTITUTION:A reinforcing material is formed with a core sheath type composite fiber which has a core component of polyethylene-2 and 6-naphthalate having a main component of ethylene phthalein-2 and 6-naphthalate, and in which a sheath component, having a main component of polyamide, is arranged in the periphery of the core component. In this case, the proportion of the core component is made 30-90wt.%, the strength of the composite fiber 7.0g/d or more, ductility 20% or less, initial tensil resistance 90g/d or more, and dry heat shrinkage percentage 5% or less. This constitution can improve the thermal resistance and the fatigue resistance of rubber.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a conveyor belt reinforcing material, and more specifically, the core component contains polyethylene-2°6-naphthalate (
This invention relates to a conveyor belt reinforcing material made of a core-sheath type composite fiber whose sheath component is polyamide as a main component (hereinafter referred to as 2.6-PEN), and is particularly characterized by the characteristics of the composite fiber.

The present invention also relates to a conveyor belt in which the above-mentioned conveyor belt reinforcing material is embedded in rubber as a tensile material.

[Prior Art] Polyester fibers, typified by polyethylene terephthalate fibers, have the characteristics of high strength and high elastic modulus, and are used as reinforcing materials for conveyor belts. However, in the case of the conveyor belt, the reinforcing material made of polyester fibers is thermally deteriorated by direct sunlight and radiant heat under the scorching sun, resulting in a decrease in strength and loss of adhesion to the rubber, resulting in peeling. As a means to improve the adhesion between polyester fibers and rubber, composite fibers containing polyester as a core component and polyamide as a sheath component are disclosed, for example, in JP-A-49-85315 and JP-B-Sho 62-420.
61, and Japanese Patent Application Laid-Open No. 1-9723.

[Problem to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 49-85315, Japanese Patent Publication No. 62-42
Fibers with a core-sheath composite structure proposed by methods such as Japanese Patent Publication No. 061 and Japanese Patent Publication No. 1-9723 have improved adhesion to rubber due to the polyamide component of the sheath, and improved modulus due to the polyester component of the core. The aim was to maintain dimensional stability. Although adhesion is certainly sufficiently improved by this method, the modulus and dimensional stability decrease as the nylon component of the sheath increases, and the modulus and dimensional stability possessed by polyester fibers cannot be sufficiently maintained. On the other hand, it was not possible to sufficiently reduce the heat resistance and fatigue resistance of nylon in rubber.

Additionally, polyester fibers generally have poor heat resistance in rubber. That is, at high temperatures, the ester bonds of polyester fibers are broken due to the action of moisture and amine compounds in the rubber, causing a decrease in strength. It also has poor adhesion to rubber, especially when repeatedly exposed to high-temperature atmospheres for long periods of time, and its adhesion to rubber decreases significantly. Although the high strength and high modulus properties that are characteristic of polyester fibers are effective, polyester fibers have the disadvantage that they deteriorate due to heat, resulting in a decrease in strength and a decrease in adhesive strength with rubber.

By overcoming the above problems, the present invention provides a reinforcing material for conveyor belts that has excellent adhesion to rubber, has higher modulus and dimensional stability than polyester, and has improved heat resistance and fatigue resistance in rubber. An object of the present invention is to provide a suitable conveyor belt reinforcing material and a conveyor belt reinforced with the reinforcing material.

In particular, it has high modulus, improved dimensional stability, and improved heat resistance in rubber (hereinafter referred to as heat resistance in rubber) that could not be achieved with conventional technology, and is resistant to peeling of the polymer at the core-sheath composite interface. An object of the present invention is to provide a conveyor belt reinforcing material having sufficient durability and a conveyor belt reinforced with the reinforcing material.

[Means and effects for solving the problems] The structure of the present invention is as follows: (1) In a conveyor belt reinforcing material, the fibers forming the reinforcing material are made of polyethylene whose main component is ethylenenaphthalene-2,6-dicarboxylate. - A core-sheath type composite fiber having a core component of 2,6-naphthalate and a sheath component mainly composed of polyamide surrounding the core component, wherein the ratio of the core component forming the composite fiber is 30. ~90% by weight
A conveyor belt, wherein the composite fiber has a strength of 7.0 g/d or more, an elongation of 20% or less, an initial tensile resistance of 90 g/d or more, and a dry heat shrinkage rate of 5% or less. Reinforcement material.

(2) In the conveyor belt reinforcing material of (1) above, polyethylene-2,6-naphthalate forming the core component of the composite fiber has an intrinsic viscosity 5 - - [η] of 0.5 or more and a birefringence of 230xlO-8 ~35
0x10-3 to 350x10-3, density 1. 340
g/cm” or more, the sulfuric acid relative viscosity (ηr) of the polyamide forming the sheath component is 2.8 or more, and the birefringence is 4.
5X10-'' or more, has a density of 1.135 g/Cm or more, and has a highly oriented, highly crystalline fiber structure in both the core component and the sheath component.

(3) In a conveyor belt, a treated reinforcing material having a resorcinol/formalin/latex layer formed on the surface obtained by dipping the conveyor belt reinforcing material described in (1) above is embedded in rubber as a tensile material. A conveyor belt characterized by:

It is in.

The composite fiber applied as a reinforcing material for a conveyor belt according to the present invention is a composite fiber whose core component is 2.6-PEN and whose sheath component is polyamide, and this composite fiber cannot be obtained by conventional technology. , has a higher modulus than polyester, heat resistance in rubber, heat resistant adhesion, and peel durability of the polymer at the core-sheath composite interface, and these characteristics are:
2) The specified birefringence of the 6-PEN and polyamide fiber sections forming the core and sheath, respectively, can be indicated by parameters consisting of a combination of densities.

Strength of composite fiber7. In order to obtain Og/d or more, the core component 2.6-PEN fiber has an intrinsic viscosity [η] of 0.5 or more, preferably 0. It has a high viscosity of 6 or more.

2.6-As with the PEN core component, the polyamide sheath component polymer also requires a high degree of polymerization in order to obtain a high-strength conjugate fiber, and the relative viscosity of sulfuric acid is 2.8 or more, preferably 3.0 or more. The polyamide sheath component contains copper salt as a thermal oxidative deterioration inhibitor.
and other organic and inorganic compounds are added. In particular, copper salts such as iodized steel, copper acetate, copper chloride, and copper stearate are used in an amount of 30 to 500 ppm as copper, and alkali metal halides such as potassium iodide, sodium iodide, and potassium bromide are added in an amount of 0.
It is preferable to contain 0.01 to 0.5% by weight and/or 0.01 to 0.1% by weight of an organic or inorganic phosphorus compound.

The ratio of the 2.6-PEN core component of the composite fiber is 30 to 9.
It is 0% by weight. If the 2.6-PEN component is less than 30% by weight, a composite fiber that can effectively utilize the modulus and dimensional stability of the 2.6-PEN component cannot be obtained, and a desirable conveyor belt reinforcing material cannot be obtained. .

On the other hand, when the 2.6-PEN core component accounts for 90% by weight or more, when the composite fiber is used as a reinforcing material for a conveyor belt and the reinforcing material is used as a tensile material for a conveyor belt, the adhesion to rubber becomes poor. Unfortunately, it is not possible to improve the heat resistance of conveyor belt reinforcing materials in rubber.

In the composite fiber, both the 2.6-PEN core component and the polyamide sheath component are highly oriented and crystallized, and the 2.6-PEN core component and polyamide sheath component are highly oriented and crystallized.
The birefringence of the PEN core component is 2aoxio-”~350X1
It is desirable to keep it within the range of 0-”, and 230
If it is less than 350 x 10-", the strength of the composite fiber may not be 7.0 g/d or more, and the initial tensile resistance may not be 90 g/d or more. If it is more than 350 x 10-", the dimensional stability and fatigue resistance may be poor. Improvements may not be made.

On the other hand, the birefringence of the polyamide sheath component is 45 x 10-3 or more, usually 50 x 10-'' or more, which is highly oriented.If the birefringence is less than 45 x 10-'', the composite fiber has high strength and high initial tensile resistance. difficult to obtain.

The birefringence of the core-sheath composite fiber can be measured as follows. That is, the sheath portion is directly measured using a transmission interference microscope, and the core portion is measured using a transmission interference microscope after dissolving the polyamide sheath component in formic acid, sulfuric acid, fluorinated alcohol, or the like.

The density is 2.6-PEN core component is 1.340g/cm
``The polyamide sheath component is 1.135g/cm''
As mentioned above, it is desirable that the fiber is highly crystallized, and by having a density of each of the above specific values or more, the composite fiber has excellent dimensional stability and fatigue resistance, and can be used as a reinforcing material for a conveyor belt. When the reinforcing material is used as a tensile member of a conveyor belt, the heat resistance in the rubber of the tensile member is significantly improved.

2.6-The density of the PEN core component is determined by dissolving and removing the polyamide sheath component with formic acid, sulfuric acid, fluorinated alcohol, etc., and the density of the polyamide sheath component is 2.6 times the density of the composite fiber.
- It can be calculated from the density of the PEN core.

The composite fiber characterized by the above has a high strength of 7°0 g/d or more, an initial tensile resistance of 90 g/d or more, and an elongation of 20% or less.

More preferable composite fiber properties include strength of 7.3 g/d or more, initial tensile resistance of 100 g/d or more, and elongation of 8 to 16%.
This can be achieved by appropriately combining the above conditions.

The composite fiber can be manufactured by the novel method shown below.

In order to obtain the above-mentioned 2) polymer physical properties of the 6-PEN core component, a polymer consisting essentially of 2.6-PEN with an intrinsic viscosity [η] of 0.5 or more, usually 0.6 or more is used.

The polyamide sheath component polymer has a sulfuric acid relative viscosity of 2°8 or more,
Usually, a polymer with a high polymerization degree of 3.0 or more is used.

It is preferable to use two extruder type spinning machines for melt spinning the polymer. 2) 6-PEN and polyamide polymer melted in each extruder are introduced into a composite spinning pack, passed through a composite spinning nozzle, and spun into a composite fiber with 2.6-PEN in the core and polyamide in the sheath, Spun yarn and eggplant.

The spinning speed is 300 m/min or more. Immediately below the spinneret, a heated atmosphere of 200° C. or higher, preferably 260° C. or higher is created over a distance of 10 cm or more and within 1 m by providing a heat insulating cylinder, a heating cylinder, etc. After passing through the heating atmosphere, the spun yarn is quenched and solidified with cold air, and after being applied with an oil agent, it is taken off by a take-off roll that controls the spinning speed. Control of the heating atmosphere directly under the spinneret is important in order to maintain stringiness. The undrawn yarn taken off is usually -
Stretch continuously without winding up.

Next, the undrawn yarn is continuously heated to 180°C or higher, preferably 2°C.
It is hot stretched at a temperature of 00°C or higher.

The stretching is carried out in two or more stages, usually three or more stages, and the stretching ratio is in the range of 2.0 to 6.5 times. Adoption of such high-temperature hot stretching according to the present invention contributes to improving the durability of the composite interface. The stretching temperature in the third stage of stretching is low, for example 160
If the temperature is below 180°C, interfacial delamination between the 2.6-PEN core component and the polyamide sheath component may occur during conveyor belt processing and when the conveyor belt is used at high speeds. be. Moreover, if the stretching ratio is 6.5 times or more, the change during stretching is large and interfacial peeling may occur, and the fatigue resistance may be lowered, which is not preferable.

[Examples] Examples 1 and 2) Comparative Examples 1 to 3 Polyethylene-2°6-naphthalate (2,6-PEN) with intrinsic viscosity [η) O, SO and 0.02% by weight of iodized steel
and hexamethylene adipamide (N66: sulfuric acid relative viscosity ηr3.3) containing 0.1% by weight of potassium iodide were respectively melted in a 40φ spinner and guided into a composite spinning pad to form a core-sheath composite. 2.6PE in the core from the spinneret
N. The sheath part was spun as a composite yarn of polyamide to obtain a spun yarn. The proportions of the core component and sheath component were varied as shown in Table 1. The cap has a hole diameter of 0. A hole having a diameter of 4 mm and 90 holes was used. The polymer temperature was 2.6-PEN was melted at 300°C and polyamide was melted at 290°C, and the spinning pack temperature was set at 3.
It was spun at 00°C. A 30 cm heating cylinder was attached directly below the mouthpiece, and the atmosphere inside the cylinder was heated to 290°C.

The atmospheric temperature is the atmospheric temperature measured at a position 10 cm below the spinneret surface and 1 cm away from the single yarn running on the outermost circumference of the spun yarn.

An annular chimney 3-=14- with a length of 400 mm was attached below the heating cylinder, and cold air was blown at 25° C. at a rate of 40 m/min from around the yarn at a right angle to the yarn to cool the yarn.

After applying an oil agent, the yarn speed was controlled with a take-up roll rotating at the speed shown in Table 1, and then the yarn was drawn continuously without being wound up. The film was stretched in 3 stages using 5 pairs of Nelson type rolls, then subjected to a relaxation heat treatment with 3% relaxation, and then wound up. The stretching conditions were a take-up roll temperature of 60°C, a first stretching roll temperature of 120°C, a second stretching roll temperature of 190°C, a third stretching roll temperature of 225°C, and a tension adjustment roll after stretching that was not heated. The first stage stretching ratio was 70% of the total stretching ratio, and the remainder was divided into two stages for stretching. Silk was produced by varying the spinning speed, total draw ratio, etc.
The spinning speed was adjusted so that the fineness of the drawn yarn was about 500 denier.
The discharge amount was changed in accordance with the stretching ratio (Example 1,
2) Comparative Example 1). Two of the obtained drawn yarns were combined into 100
It was set to 0 denier.

The spinning conditions, the obtained drawn yarn properties, and the fiber structure parameters were determined using polyethylene terephthalate (PET) fiber (1
000-192-702C) (Comparative Example 2) and Nylon 66 fiber (840-136-1781) (Comparative Example 3)
A comparative test was conducted on the following. Each condition and fiber properties are as shown in Table 1.

(Margins below) In Example 1.2 and Comparative Example 1.2, the conveyor belt reinforcing material made of each fiber shown in Table 1 was used, the warp was 1000D/2) the weft was 2000D/2 twisted yarn. Without, woven fabric density (warp/weft) 70X30
A 15 cm woven fabric was obtained. However, N66 in Comparative Example 3 had a warp of 840D/2 and a weft of 1680D/2 to obtain a pear-shaped fabric. This woven fabric was applied with an adhesive and heat treated in a conventional manner using a dipping machine manufactured by Ritzler Co., Ltd. to obtain a dipped cord woven fabric.

The dip liquid contained an adhesive component consisting of 20% resorcinol, formalin, and latex, and was adjusted so that about 3% of the adhesive component adhered to the fabric.

The heat treatment was performed at 225° C. for 80 seconds while stretching the dip cord so that the intermediate elongation was approximately 4%.

Nylon 66 in Comparative Example 3 was stretched and treated under the same heat treatment conditions so that the intermediate elongation was about 9%. Further, the polyester in Comparative Example 3 was subjected to a two-bath adhesive treatment by a conventional method, heat treated at 240°C for 120 seconds, and stretched to give an intermediate elongation of about 5%.

The thus obtained dip-treated conveyor belt reinforcing material was embedded in rubber in the same manner as when used as a tensile member for conveyor belts, and test pieces were made to evaluate heat resistance, adhesion, fatigue resistance, etc. in rubber. . The results were as shown in Table 2.

The conveyor belt reinforcing material according to the present invention has higher modulus and dimensional stability than conventional reinforcing materials made of polyester fibers, and has better heat resistance in rubber and heat resistance than conventional reinforcing materials made of polyester fibers. It shows high strength with significantly improved adhesion and fatigue resistance.

Furthermore, the conveyor belt reinforcing material according to the present invention is a conveyor belt reinforcing material that has significantly improved modulus and dimensional stability compared to conventional reinforcing materials made of nylon fibers.

(The following is a blank space) 19- Table 2 [Effects of the invention] The conveyor belt reinforcing material according to the present invention has a modulus higher than that of conventional polyester, improved dimensional stability,
Moreover, compared to a conveyor belt in which the reinforcing material made of conventional polyester is buried as a tensile body, the conveyor belt in which the conveyor belt reinforcing material according to the present invention is buried as a tensile body has a lower strength of the reinforcing material buried in the belt. The rubber heat resistance and adhesion properties, especially after being exposed to high temperature history, and fatigue resistance are significantly improved, so that the durability of the conveyor belt is extremely good.

Claims (3)

[Claims] (1) In a conveyor belt reinforcing material, the fibers forming the reinforcing material have a core component of polyethylene-2,6-naphthalate whose main component is ethylene-naphthalene-2,6-dicarboxylate, and the core component is It is a core-sheath type composite fiber with a sheath component mainly composed of polyamide, and the ratio of the core component forming the composite fiber is 30 to 90% by weight.
A conveyor belt, wherein the composite fiber has a strength of 7.0 g/d or more, an elongation of 20% or less, an initial tensile resistance of 90 g/d or more, and a dry heat shrinkage rate of 5% or less. Reinforcement material. (2) In the conveyor belt reinforcing material according to claim (1), polyethylene-2,6-naphthalate forming the core component of the composite fiber has an intrinsic viscosity [η] of 0.5 or more and a birefringence of 230. ×10^-^3～350×10^-^
3. The density is 1.340 g/cm^3 or more, and the sulfuric acid relative viscosity (ηr) of the polyamide forming the sheath component is 2.8
Above, birefringence is 45×10^-^3 or more, density is 1.1
35 g/cm^3 or more, and wherein both the core component and the sheath component have a highly oriented and highly crystalline fiber structure. (3) Regarding the conveyor belt, Claim No. 1 (1)
A conveyor characterized in that the reinforcing material for the conveyor belt according to item (2) is dip-treated and a layer of resorcinol/formalin/latex is formed on the surface of the reinforcing material, which is embedded in rubber as a tensile material. belt.