JPH02154012A - Conveyor belt reinforcing material and conveyor belt - Google Patents

Abstract

PURPOSE:To obtain the subject reinforcing material having dimensional stability, excellent adhesivity and high fatigue resistance by using a sheath-core conjugate fiber composed of a core component consisting of a polyester containing ethylene terephthalate as a main component and a sheath component composed mainly of a polyamide. CONSTITUTION:The objective fiber constituting the reinforcing material of a conveyor belt is a sheath-core conjugate fiber composed of (A) a core component consisting of a polyester composed mainly of ethylene terephthalate and (B) a sheath component composed mainly of a polyamide and arranged around said core component. The ratio of the component A in the conjugate fiber is 30-90wt.% and the fiber has a strength of >=7.5g/d, an elongation of <=20%, an initial tensile modulus of >=60g/d and a dry-heat shrinkage of <=7%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a conveyor belt reinforcing material, and more specifically to a conveyor belt reinforcing material made of a composite fiber whose main components are polyester as a core component and polyamide as a sheath component. Regarding materials, especially the above-mentioned composites! ! It is characterized by the characteristics of miscellaneous.

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

[Prior Art] Polyester IIN, typified by polyethylene terephthalate fiber, has the characteristics of high strength and high elastic modulus, and is used as a reinforcing material 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 this polyester material and rubber, composite fibers containing polyester as a core component and polyamide as a sheath component are disclosed, for example, in JP-A No. 49-85315 and JP-B No. 62-4.
It is described in Publication No. 2061.

[Problem to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 49-85315 and Japanese Patent Publication No. 62-4
The fiber with a core-sheath composite structure proposed by the method of Publication No. 2061 is intended to have improved adhesion to rubber by the polyamide component of the sheath, and to maintain modulus and dimensional stability by the polyester component of the core. Met. Although this method certainly improves adhesion,
The modulus and dimensional stability decreased as the nylon component of the sheath increased, and it was not possible to sufficiently maintain the modulus and dimensional stability of polyester mN, while on the other hand, the heat resistance and dimensional stability of nylon in rubber It was not possible to take full advantage of fatigue properties, etc.

In addition, ordinary polyesters such as polyethylene terephthalate and ordinary polyamides such as nylon 6 and nylon 66 have poor compatibility with each other, so when VJ is manufactured using ordinary manufacturing methods, both polymers with a core-sheath composite structure It was not possible to obtain a material with sufficient durability for practical use because it was easy to peel and break at the interface.

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. In the case of a core-sheath composite fiber made of polyester and polyamide produced by a conventional spinning method, it was easy to peel and break at the interface between both polymers in the core-sheath composite structure, and did not have sufficient durability for practical use. In particular, the polymer interface was destroyed by the repeated stretching and compression fatigue experienced during the drawing process, conveyor belt processing processes such as twisting and dipping, belt vulcanization process, and belt driving, and the performance expected of the original core-sheath composite fiber was not achieved by 1q. .

By overcoming the above problems, the present invention provides a reinforcing material for conveyor belts that has excellent adhesion to rubber, has high modulus and dimensional stability close to that of 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 present invention has the following features: (1) A conveyor belt reinforcing material, in which the fibers forming the reinforcing material have a core component of poly-1 stellate containing ethylene terecrate as a main component; A core-sheath type composite fiber assembly consisting of a sheath component mainly composed of polyamide surrounding the core component,
The ratio of the core component made of the polynisdel in the composite mH is 30 to 90% by weight, the strength of the composite fiber is 7.5q/d or more, the elongation is 20% or less, and the initial II tensile resistance is 600/ Conveyor belt reinforcement material with a dry heat shrinkage rate of 7% or less.

(2) In the conveyor belt reinforcing material of (1) above, the conveyor belt reinforcing material has a composite 1jAH terminal modulus of 20 o/d or less and an initial tensile resistance of 90 a/d or more.

(3) In the conveyor belt reinforcing material of (1) above, the intrinsic viscosity (η
) is 0.8 or more, birefringence is 160 x 10” to 190
X10-5 density is 1,395 Q/cm3 or more, DS
The peak temperature of the melting curve measured at C is 247°C or higher, and the polyamide forming the sheath component IiI! I acid relative viscosity (77r') is 2.8 or more, birefringence is 50X10'
The above conveyor belt reinforcing material has a density of 1,140a/α3 or more, and both the core component and the sheath component have a highly oriented and highly crystalline fiber structure.

(4) In a conveyor belt, a treated reinforcing material obtained by dipping the conveyor belt reinforcing material described in (1) above and having a layer of resorcinol, formalin, or latex formed on its surface is embedded in rubber as a tensile material. It's on a conveyor belt.

The composite fiber used as a reinforcing material for conveyor belts according to the present invention has a high modulus close to that of polyester, heat resistance in rubber, and peeling durability of the polymer at the core-sheath composite interface, which could not be achieved with conventional technology. The specified birefringence, density, and DS of the polyester and polyamide fiber portions forming the sheath, respectively, are determined by the peak temperature and the parameters consisting of a combination of high initial +9 tensile resistance and low terminal modulus of the polyester core component fibers. be able to.

In order to obtain a composite fiber strength of 7.5 a/d or more, the core component polyethylene terephthalate 18M has a high intrinsic viscosity (η) of 0.7 or more, preferably 0°8 or more.

Similar to the polyester 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.

Copper salts and other organic and non-silicon compounds are added to the polyamide sheath component as thermal oxidative deterioration inhibitors. Especially for iodination, copper salts such as copper acetate, copper chloride, copper stearate, etc. are used as copper at a concentration of 30 to 500 ppm, and alkali metal halides such as potassium iodide, sodium iodide, potassium bromide, etc. are added at a concentration of 0.0 ppm.
It is preferable to contain 1 to 0.5 ffiffi% and/or 0.01 to 0.1 weight % of an organic or solid phosphorus compound.

The ratio of the polyester core component of the composite l11i is 30~
It is 901ffi%. 30% by weight polyester component
If the amount is less than 9% by weight, it is impossible to make effective use of the modulus and dimensional stability of the polyester component to make a composite composite material, and it is not possible to use the preferred conveyor belt reinforcing material. When the composite fiber is used as a conveyor belt reinforcement material and the reinforcement material is used as a tensile member of the conveyor belt, it has poor adhesion to rubber, and the heat resistance of the conveyor belt reinforcement material in the rubber deteriorates. Improvements cannot be achieved.

In the composite fiber, both the polyester core component and the polyamide sheath component are highly oriented and crystallized, and the birefringence of the polyester core component is 160X10-190X10''.
It is desirable to keep it within the range of 160X10
-Composite if less than 3! &IN strength of 7.50/d or more,
The initial tensile resistance may not exceed 600/d. Further, if it exceeds 190 x 10', dimensional stability and fatigue resistance may not be improved.

On the other hand, the birefringence of the polyamide sheath component is 50 x 10" or more, usually 55 x 10" or more, which is highly oriented.
If it is less than 0x10'', it is difficult to obtain a composite fiber with high strength and high initial tensile resistance.

The birefringence of the core-sheath composite IHIt 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 of the polyester core component is 1.395q103 or more,
It is desirable that the polyamide sheath component is 1.1400/ClA3 or higher and is highly crystallized, and by having a density of each of the above specific values or higher, the composite TI material has excellent dimensional stability and fatigue resistance, and is suitable for use in conveyors. 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.

The density of the polyester 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 complex! It can be calculated from the density of IH and the density of the polyester core.

The peak temperature of the DSC melting curve showing the characteristics of the crystal structure of the polyester core component in the composite material is 247 ° C.
The temperature is preferably 248° C. or higher. The peak temperature is high (corresponds to large crystals and/or good crystal integrity, and stable miscellaneous structure).If the melting peak temperature of the polyester core component fiber is 2.
If the temperature is lower than 47°C, the desired modulus, dimensional stability, and fatigue resistance may not be obtained.

Said composite! Another feature reflecting IN's 11 mm construction is that the polyester core component mM has a high initial tensile resistance of 900/d or more and a low terminal modulus of 20 q/d or less. The characteristics of polyester fibers, which have high initial tensile resistance and low terminal modulus, are that there is little loss of strength at the culm when conveyor belted, and fatigue resistance is improved. The terminal modulus is determined by 2.0% from the cutting elongation on the SS curve in a fiber tensile test.
The stress increment between the point on the curve subtracted by 4% and the cutting point is 2.4
It is l1fI (Q/d) divided by X10-2, and the conditions of the tensile test are in accordance with JIS-L1017.

The composite fiber characterized by the above has a high strength of 7°50/d or more, an initial tensile resistance of 60 g/d or more, and an elongation of 20% or less.

More preferable composite 11M properties are strength 8 Cl/6 or more,
The initial tensile resistance is 70 o/d or more and the elongation is 8 to 16%, which can be achieved by appropriately combining the above conditions.

The composite m-fiber is manufactured by the novel method shown below.

In order to obtain the polymer physical properties of the polyester core component described above, a polymer consisting essentially of polyethylene terephthalate and having an intrinsic viscosity (η) of 0.75 or more, usually 0.85 or more is used. In addition, in order to produce uAN with excellent heat resistance, it is important to spin a polymer with a low carboxyl terminal M of 11 degrees. Techniques such as addition are applied, and examples of the capping agent include oxazolines, epoxies, carbodiimides, ethylene carbonate, silica esters, malonic esters, and the like.

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 a second base extruder type spinning kiln for melt spinning the polymer. The polyester and polyamide polymers melted by each extruder are introduced into a composite spinning bag, and spun into composite fibers with polyester in the core and polyamide in the sheath through a composite spinning nozzle.

The spinning speed is 1500 m/min or more, preferably 2000 m/min.
The speed should be at least 1/min. Immediately below the spinneret, a temperature of 200°C or higher, preferably 260°C, is applied for a distance of 10cm or more and within 1m.
A heated atmosphere above ℃ is created by providing a heat insulating cylinder, a heating cylinder, etc. After passing through the above-mentioned heated atmosphere, the spun yarn is quenched and solidified with cold air, and then an oil agent is applied! After that, it is taken up by a take-up roll that controls the spinning speed. Control of the heating atmosphere directly below the spinneret is important in order to maintain spinnability during high-speed spinning. The bowed undrawn yarn is usually −
Stretch continuously without winding up. The birefringence of the undrawn yarn sampled on the take-up roll for the purpose of understanding the physical properties of the undrawn yarn before stretching is that the polyamide sheath part is 20X10-
3 or more, preferably 30X10' or more, the polyester core is also 20X10' or more, preferably 30X10'
It is highly oriented.

The adoption of high-speed spinning improves the modulus, dimensional stability, and
This brings about the effect of improving fatigue resistance, but surprisingly, the durability of the core-sheath composite interface is significantly improved. Unlike the conventional low-speed spinning method, in which a highly hygroscopic and crystallized polyamide component is combined with an amorphous polyester component, in the high-speed spinning method, the polyamide component,
It is thought that the fact that both the polyester components are in a state where oriented crystallization progresses, and that the stretching ratio after spinning is small can contribute to the durability of the composite interface.

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 1.4 to 3.5 times. The use of such high-temperature thermal stretching according to the present invention also contributes to improving the composite interface durability. The stretching temperature in the third stage of stretching is low, for example 160
Below 180°C, stretching often causes interfacial delamination between the polyester core component and the polyamide sheath component during conveyor belt processing and when conveyor belts are used at high speeds.

[Example] Example-1 and 2) Comparative Examples 1 to 3 Intrinsic viscosity (η) 1.05, carboxyl end group concentration 10
．． 5eQ/10”Q polyethylene terephthalate (
PET) and 0.02% by weight for iodide and 0.02% by weight for iodide.
66/6T (80:20 weight ratio) copolyamide (relative viscosity of sulfuric acid, ηr3.2) containing 1% by weight, or hexamethylene adipamide (N66:relative viscosity of taic acid, ηr3゜3) was added to a 40φ engineering extruder, respectively. It was melted in a die spinning machine, introduced into a composite spinning pack, and spun from a core-sheath composite spinneret into a composite yarn with polyethylene terephthalate in the core and polyamide in the sheath.

The proportions of the core component and sheath component were varied as shown in Table 1. The cap used had a hole diameter of 0.4 mφ and 90 holes. Polyethylene terephthalate was melted at 295°C and polyamide was melted at 290°C, and the spinning back temperature was set at 300°C. A 15 cm heating cylinder was attached directly below the mouthpiece, and the atmosphere inside the cylinder was heated to 290°C. The ambient temperature is the ambient temperature measured at a position 10α below the mouth surface and 1 crtrm from the outermost thread. A 400M long annular chimney is installed under the heating cylinder, and the temperature is 40m at 25℃ from the circumference of the yarn.
/ minute of cold air was blown perpendicularly to the yarn to cool it. Then, after applying an oil agent, the yarn speed was controlled with a bow-cutting 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 three stages using five 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 for 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. The yarn was produced by changing the spinning speed, total drawing ratio, etc., but the fineness of the drawn yarn was about 10.
The discharge amount was varied in accordance with the spinning speed and the stretching ratio so as to obtain 00 denier (Example 1゜2) Comparative Example 1.2)
.

The spinning conditions, the obtained drawn yarn properties, and the fiber M structural parameters were determined using polyethylene terephthalate (PET>!1 fibers).
1000-192-7020) (Comparative Example 3). Each condition and 1aN characteristics are as shown in Table 1.

(Left below) For example 1.2 and comparative examples 1 to 3, the conveyor belt reinforcing material made of each fiber shown in Table 1 was twisted with a warp of 10000/2) a weft of 2000D/2. With and without, tied fabric density (warp/weft) 70
A 30/5 cm fabric was obtained. This woven fabric was applied with an adhesive and heat treated in a conventional manner using a dipping iron manufactured by Ritzler 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 5%.

Nylon 66 in Comparative Example 4 was treated under the same heat treatment conditions.
It was stretched and processed so that the intermediate elongation was about 9%.

Further, the polyester in Comparative Example 3 was subjected to a two-bath adhesion treatment in a conventional manner, 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 a modulus and dimensional stability equal to or higher than that of the conventional reinforcing material made of polyester IN, and has a higher modulus and dimensional stability in rubber than the reinforcing material made of conventional polyester fiber. It shows high strength with significantly improved heat resistance, heat-resistant 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.

(Left below) [Effects of the Invention] The conveyor belt reinforcing material according to the present invention has a dimensional stability equal to or greater than that of conventional polyester, and has improved dimensional stability compared to conventional polyester reinforcing materials. As a tensile material, compared to a buried conveyor belt,
The conveyor belt in which the conveyor belt reinforcing material according to the present invention is embedded as a tensile member has the following properties: Fatigue resistance is significantly improved, so the durability of the conveyor belt is extremely good.

Claims (4)

[Claims] (1) In a conveyor belt reinforcing material, the fibers forming the reinforcing material are of a core-sheath type, consisting of a core component made of polyester containing ethylene terephthalate as a main component, and a sheath component mainly composed of polyamide surrounding the core component. It is a composite fiber,
The ratio of the core component made of the polyester in the composite fiber is 30 to 90% by weight, the strength of the composite fiber is 7.5 g/d or more, the elongation is 20% or less, and the initial tensile resistance is 60 g/d or more. , a conveyor belt reinforcing material characterized by a dry heat shrinkage rate of 7% or less. (2) In the conveyor belt reinforcing material according to claim (1), the terminal modulus of the composite fiber is 20 g.
/d or less, and an initial tensile resistance of 90 g/d or more. (3) In the conveyor belt reinforcing material according to claim (1), the polyester forming the core component of the composite fiber has an intrinsic viscosity (η) of 0.8 or more and a birefringence of 160×10
^-^3~190x10^-^3, density is 1.395g
/cm^3 or more, the peak temperature of the melting curve measured by DSC is 247°C or more, the sulfuric acid relative viscosity (ηr) of the polyamide forming the sheath component is 2.8 or more, and the birefringence is 50×
10^-^3 or more, the density is 1.140 g/cm^3 or more, and both the core component and the sheath component have a highly oriented and highly crystalline fiber structure. (4) 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.