JPH0441A - Toothed belt - Google Patents

Abstract

PURPOSE:To improve durability and fatigue-proof property of a toothed belt by making weft and/or wrap of the cloth, which is covering the surface of a tooth face, of the compound fiber composed of polyethylene-2,6-naphthalate core component and polyamide sheath component. CONSTITUTION:Wrap and weft, which is nealy in parallel with the longitudinal direction of a belt, of the cloth covering the surface of a toothed surface is made of the core and sheath type compound fiber composed of polyethylene-2,6- naphthalate core component, which is mainly composed of ethylene naphthalane-2,6-dicarboxilate, and sheath component, which is mainly composed of polyamide, surrounding the periphery of the core component. A limit viscosity (eta) of 2,6-PEN fiber of the core component for getting the strength more than 7.0g/d of the compound fiber is a high viscosity more than 0.5, and a ratio of the core component is 30-90weight%, and the polyamide sheath component needs a high polymerization degree, and a relative viscosity with sulfuric acid is more than 2.8, and copper salt and other organic and non-organic compound are added as the thermal oxidation and deterioration inhibitor.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a toothed belt, and more specifically, the fibers forming the covering fabric that reinforces the tooth surfaces of the toothed belt are made of special fibers to improve durability. This invention relates to a toothed belt with improved characteristics such as durability and fatigue resistance.

[Prior Art] Toothed belts for power transmission in various machines, automobiles, office equipment, etc. have conventionally been provided with a reinforcing fiber fabric on the outermost layer of the tooth surface, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-147142.
The method described in the above publication is known, in which a rubber member in which at least ceramic whiskers are dispersed and blended is impregnated and adhered to a fiber member as a cover layer, and this cover layer is adhered to the surface of the belt with the rubber member exposed. and
Polyamide fibers are used as the fiber member.

[Problems to be Solved by the Invention] In the case of the above-mentioned prior art, a rubber member containing ceramic whiskers is attached to a cover fabric made of polyamide fibers, and the use of this rubber member improves the survival rate of the fabric. However, in the case of toothed belts that rotate at high temperatures and high speeds, such as automobile timing belts, the modulus and dimensional stability are poor, and the toothed belt may stretch to its full extent, resulting in unstable meshing with the toothed pulley. However, it has not yet been put into practical use.

An object of the present invention is to improve the covering fabric that reinforces the tooth surface of the toothed belt, to improve the modulus and dimensional stability of the covering fabric, and to improve the durability and fatigue resistance of the toothed belt. .

In addition, a fabric made of polyester fiber is generally used as a covering fabric to reinforce the tooth surface of a toothed belt, but in the case of the polyester fiber fabric, although it is excellent in high strength and high elastic modulus, The problem has been that it deteriorates due to heat and its strength decreases, and that it also loses its adhesion to rubber and is easily peeled off.

[Means and effects for solving the problems] The structure of the present invention is as follows: (1) A belt body made of rubber or elastic resin in which a tensile material is embedded, and a tooth surface on one side of the belt body. , in a toothed belt in which the surface of the tooth surface is covered with a fabric, the fabric covered on the surface of the tooth surface is woven in a direction substantially parallel to the length direction of the belt and/or in a direction perpendicular to the weft. A core-sheath type in which the warp threads have a core component made of polyethylene-2,6-naphthalate whose main component is ethylene-naphthalene-2,6-dicarboxylate, and a sheath component mainly composed of polyamide surrounding the core component. It is a composite fiber of
The ratio of the core component forming the core-sheath type composite fiber is 30 to 90.
% by weight, and the strength of the composite fiber is 70 g/d or more,
A toothed belt characterized by being formed of fibers having an elongation of 20% or less, an initial bowing resistance of 90 g/d or more, and a dry heat shrinkage rate of 5% or less.

(2) In (1) above, the fabric is formed by using, as the weft, a twisted yarn of a core-sheath composite fiberboard in which core-sheath composite fibers made of polyethylene-26-naphthalate and polyamide are false-twisted. Toothed belt.

(3) In (1) above, a core-sheath composite fiber-covered elastic yarn in which a core-sheath composite fiber made of polyethylene-2゜6-naphthalate and polyamide is covered around the elastic yarn is used as a weft to form a fabric. A toothed belt that is characterized by a

It is in.

The composite fiber applied as the reinforcing cord for the toothed belt according to the present invention is a composite fiber whose core component is polyethylene-2,6-naphthalate (hereinafter referred to as 2.6-PEN) and whose sheath component is polyamide, The composite fiber has a high modulus higher than that of polyester, heat resistance in rubber, heat-resistant adhesion, and peeling durability of the polymer at the core-sheath composite interface, which has not been obtained using conventional technology. 2) Specified birefringence of the 6-PEN and polyamide fiber sections forming the core and sheath, respectively, as indicated by parameters consisting of a combination of densities.

In order to obtain a composite fiber strength of 7.0 g/d or more, the core component 2.6-PEN fiber has a high intrinsic viscosity [η] of 0.5 or more, preferably 0.6 or more.

2.6-Like 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 preferred reinforcing cord for toothed belts can be obtained. I can't. On the other hand, when the 2.6-PEN core component accounts for 90% by weight or more, the composite fiber is used as a reinforcing cord for a toothed belt, and when the cord is used as a tensile member of a toothed belt, it is difficult to combine with rubber. Adhesion is poor, and improvements such as heat resistance of reinforcing cords for toothed belts in rubber cannot be achieved.

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.
Birefringence of PEN core component is 230X10-”~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 45X10-3 or more, usually 50X10-" or more, which is highly oriented. If the birefringence is less than 45X10-", it is difficult to obtain a composite fiber with high strength and high initial tensile resistance. Have difficulty.

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
”In total, the polyamide sheath component is 1.135g/cITIs.
As mentioned above, it is desirable that the fiber is highly crystallized, and by having a density equal to or higher than the above-mentioned specific values, the composite fiber has excellent dimensional stability and fatigue resistance, and can be used as a reinforcing cord for a toothed belt. When the cord is used as a tensile member of a toothed 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 is 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 2.6PEN in the core and polyamide in the sheath. Yarn and eggplant.

The spinning speed is 300 m/min or more. Immediately below the spinneret, 10Cr11 or more, 200℃ or more within 1m,
Preferably, a heating atmosphere of 260° C. or higher is created 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 taken-off undrawn yarn is usually continuously drawn without being wound 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 the stretching is low, for example 160
When stretched below 180°C, interfacial delamination between the 2.6-PEN core component and the polyamide sheath component occurs during toothed belt processing and when the toothed belt is used at high speeds. Sometimes. Furthermore, if the stretching ratio is 6.5 times or more, deformation during stretching may be large and interfacial peeling may occur, and fatigue resistance may be lowered, which is not preferable.

The proportion of the 26-PEN core component in the core-sheath type composite fiber is 30 to 90% by weight, the strength is 70 g/d or more, the elongation is 20% or less, and the initial tensile resistance is 90 g/d or more,
When covering the surface of the tooth surface of a toothed belt with a fabric made of a composite fiber having a dry heat shrinkage rate of 5% or less, the composite fiber is kept in a state in which elastic threads such as polyurethane fibers are stretched. The composite fiber-covered elastic yarn is wound around the elastic yarn to obtain a composite fiber-covered elastic yarn, and the composite fiber-covered elastic yarn, that is, the elastic yarn is woven in the longitudinal direction of the toothed belt, that is, as a weft, to obtain a fabric. Although the fabric may use conventionally known fibers such as nylon 66 filament as the weft, it is preferable to use the composite fibers used for the weft. When weaving the above-mentioned fabric, the composite fibers may be false-twisted and used in a stretchable state without being wound around the elastic threads.

A fabric using the above-mentioned elastic yarn is coated with an adhesive such as resorcinol, formalin, or latex, and then heat-treated. This heat treatment is performed while applying a constant tension to the weft yarns so that the stretchable yarns, which are the weft yarns, do not stretch.

A fabric treated with an adhesive using the stretchable yarn is wound around a cylindrical mold having a tooth shape on the outer circumferential surface with the stretch direction along the circumferential surface, and a tensile cord is wound spirally thereon,
Furthermore, after wrapping an unvulcanized rubber sheet of a certain thickness around it, the rubber is press-fitted into the tooth profile of the cylindrical mold by external pressure and heating using the Seitai molding method, and a fabric using elastic thread is molded. It is molded into a shape that follows the tooth profile and vulcanized.

[Example 1 and 2] Comparative Examples 1 to 3 Polyethylene with an intrinsic viscosity [η:] of 0.80 to 2.6-naphthalate (2,6-PEN) and 0.02% by weight of iodized steel and iodine Hexamethylene adipamide (N66: sulfuric acid relative viscosity ηr3.3) containing 0.1% by weight of potassium chloride is melted in a 40φ xtruder-type spinning machine, guided into a composite spinning bag, and then spun from a core-sheath composite spinneret. 2,6-P in the part
EN, the sheath part was spun as a composite yarn of polyamide, and a spun yarn was obtained. The proportions of the core and sheath components were varied as shown in Table 1. The cap used had a hole diameter of 0°4 mmφ and 45 holes. Polymer temperature is 2.6-PEN at 300°C1
The polyamides were each melted at 290°C and spun at a spinning pack temperature of 300°C. 30Cr right below the base
1 heating cylinder was attached, and the cylinder was heated to an atmospheric temperature of 290°C.

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

An annular chimney with a length of 400 mm was installed under the heating cylinder, and cold air was blown at 40 m/min at 25° C. from around the yarn at right angles 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 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 as follows: take-up roll temperature at 60°C, first stretching roll temperature at 120°C, second stretching roll temperature at 190°C, third stretching roll temperature at 225°C.
The tension adjustment roll after stretching was not heated, and 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 varying the spinning speed, total draw ratio, etc., and the discharge amount was varied in accordance with the spinning speed and draw ratio so that the fineness of the drawn yarn was about 250 denier (Example 1
, 2) Comparative Example 1). Two of the obtained drawn yarns were combined into 50
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 (5
00-96-702C) (Comparative Example 3) and Nylon 66
A comparative test was conducted on the fiber (42068) (Comparative Example 4).

Each condition and fiber properties are as shown in Table 1.

(Left below) After heating each fiber shown in Table 1 above, operon yarn (
3.Polyurethane elastic thread) 140D manufactured by DuPont Co., Ltd.
A stretchable yarn was obtained by winding the yarn in a state where it was stretched five times. The number of windings was set so that the number of windings was 200 times/m when the stretched operon thread was unwound.

The above-mentioned elastic yarn is used as the warp, and nylon 6 is used as the warp.
Weaving was carried out using 6 210D filaments. The weave structure is 2/2 twill weave, and the weave density in the relaxed state is 15 warp.
The fabric was 0 threads/5 cTrl and the weft was 150 threads and 15 cm. Resorcin, formalin, and latex were applied to the fabric and heat-treated. The dip liquid contains an adhesive component consisting of 20% resorcinol, formalin, and latex.
The adhesive component was adjusted to adhere to the cord by approximately 4%. The heat treatment was performed at 225° C. for 80 seconds. Next, the obtained fabric is wrapped so that the wefts are aligned in the direction of the tooth surface of the cylindrical mold, and an unvulcanized rubber sheet is wound on top of it (usually a high A tensile material such as a strong nylon cord was arranged, but in order to evaluate the fabric itself, this tensile material was excluded.) The rubber was pressurized and heated from the outside into the tooth profile of the cylindrical mold, and then Sulfurized. The obtained toothed cylindrical body was cut into a width of 4 cm in the weft direction to create a toothed belt. The physical properties of the weft yarns in the resulting toothed belt were measured. The results were as shown in Table 2.

(Hereinafter, blank spaces) In the toothed belt according to the present invention, the reinforcing fibers used as the warp of the fabric on which the surface of the tooth surface is coated have a core component mainly composed of polyethylene-2,6-naphthalate and a core component mainly composed of polyamide. A new reinforcing material with special characteristics consisting of a sheath component is used, and has higher modulus and dimensional stability than the reinforcing material made of polyester fiber (Comparative Example 2). It also shows that it is a high-strength reinforcing material with significantly improved heat resistance, adhesion resistance, and fatigue resistance in rubber.
Compared to the reinforcing material of Comparative Example 3), the modulus and dimensional stability are significantly improved.

[Effects of the Invention] The toothed belt according to the present invention has a warp of the fabric coated on the tooth surface, which has higher modulus and dimensional stability than polyester, and has excellent heat resistance and adhesive properties in rubber. In particular, heat-resistant adhesion and fatigue resistance after high-temperature history are significantly improved.

Therefore, the toothed belt according to the present invention has extremely excellent durability and can withstand severe conditions.

Claims (3)

[Claims] (1) A toothed belt having a belt body made of rubber or elastic resin with a tensile material embedded therein, a tooth surface on one side of the belt body, and the surface of the tooth surface covered with a fabric, Weft threads substantially parallel to the length direction of the belt of the fabric coated on the surface of the tooth surface and/or warp threads woven in a direction perpendicular to the weft threads are mainly composed of ethylenenaphthalene-2,6-dicarboxylate. A core-sheath type composite fiber consisting of a core component of polyethylene-2,6-naphthalate and a sheath component mainly composed of polyamide surrounding the core component,
The ratio of the core component forming the core-sheath type composite fiber is 30 to 90.
% by weight, and 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. A toothed belt characterized by: (2) In claim (1), a core-sheath composite fiberboard twisted yarn in which core-sheath composite fibers made of polyethylene-2,6-naphthalate and polyamide are false-twisted is used as the weft, and the fabric is A toothed belt characterized by being formed. (3) In claim (1), a core-sheath composite fiber-covered elastic yarn in which an elastic yarn is covered with a core-sheath composite fiber made of polyethylene-2,6-naphthalate and polyamide is used as a weft. , a toothed belt characterized by being made of fabric.