JPS60179239A - Manufacture of transmission belt - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of a uniform transmission belt by a method wherein a biaxially oriented tube made of a thermoplastic polyester resin is heated on a cylindrical jig with the diameter smaller than that thereof up to 70-230 deg.C to be shrinked to the circumferential surface thereof and cut off to a desired width after thermally fixed and cooled down. CONSTITUTION:A thermoplastic polyester resin with the melting point exceeding 235 deg.C is melted and extruded with circular dies to form a tubular film, into which a pressurized gas is sealed to perform a biaxial stretching thereof under a pressure to obtain a finished tubular film. The diameter of the biaxially oriented tube is set at 1.02-1.15 with respect to the diameter of a cylindrical jig, sliced to the length to match the diamensions of the cylindrical jig and mounted on the cylindrical jig. Then, the tube is heated upto 70-230 deg.C to be shrinked to the circumferential surface of the cylinder and thermally fixed. After the thermal treatment thereof preferably for 15-30min, the film is left cool, drawn and cut off to a specified length to obtain a transmission belt.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for manufacturing a drive transmission belt suitable for use in small precision transmission mechanisms such as magnetic recording devices, self-recording needles, and transmission belts for copying machines. It is related to.

<Relationship with conventional technology> Although the power to be transmitted in this type of transmission mechanism is relatively small, it is often required to faithfully follow the movement of the drive shaft and transmit 9 rotational force, resulting in backlash, slip, etc. Transmission errors must be kept to a minimum. On the other hand, with the recent development of electronic materials, there are increasing demands for excellent electrical properties, heat resistance, high strength, etc. among the performances of power transmission belts. Synthetic rubbers such as chloroprene and urethane, which have been used for this purpose in the past, are in practical use, but even with the above-mentioned performance, they lack strength and have uneven thickness, so it is difficult to say that they are fully satisfactory. Ideally, the belt should be thin in order to reduce the difference in circumference between the inner and outer surfaces of the belt when the belt is surrounded by pulleys, but the belt must have considerable strength. It is. The commonly used method of reinforcing the thread belt with cloth to compensate for the drawbacks of synthetic rubber is undesirable because it increases the thickness of the belt and complicates the manufacturing process.

On the other hand, as a method for obtaining a thermoplastic polyester resin tube, a V-shaped tube is cut to a desired width, and the tip is thermally melted or bonded to a V-hund coating. However, although the jointed tube obtained by this method is manufactured from a sheet-like material that has excellent uniformity, strength, electrical properties, and heat resistance, the joint and other parts are mechanically unstable. An inconvenient problem arises due to the different strengths of the targets. For example, the difference in thickness between the joint portion and other portions causes non-uniform mechanical strength and causes abnormal vibrations when used as a belt. Also, peeling occurs at the joint.

On the other hand, as a manufacturing method for a seamless annular body, there is a method by applying the vacuum forming method that has been widely used in conventional manufacturing of molded products from plastic sheets (for example, Japanese Patent Publication No. 58-28
Publication No. 16). These methods yield a seamless annular body in the same way as the present invention, but in the case of polyester resin sheets, they have the disadvantage that sheets with uniform thickness and long length cannot be obtained.

Not only are there dimensional restrictions, but there are also restrictions on product thickness.

<Structure of the Invention> As a result of extensive research into power transmission belts used in precision power transmission mechanisms and their manufacturing methods, the present inventors have developed a biaxially stretched tube made of thermoplastic polyester resin with a diameter smaller than that of the tube. 70-230 on a cylindrical jig with
They discovered a method of producing a conductive belt by heating the Tug to 100°C to shrink it to the outer surface of a cylindrical jig, then heat-setting, cooling, and then cutting it to a desired width.

The thermoplastic polyester resin referred to in the present invention is a crystalline polyester resin made from polyethylene terephthalate or a copolymer or polymer mixture containing ethylene terephthalate as a main component, and has a melting point of 2.
The temperature is 35°C or higher. Copolymerization components include inphthalic acid, adipic acid, sebacic acids, and neopentyl glycol.

Diols such as diethylene glycol.

A polyester block copolymer is also included as a component of the polymer mixture. The block common electricity 'merger is
A linear block copolymer consisting of a high melting point crystalline polyester segment and a low melting point amorphous polymer segment. The high melting point crystalline polyester segment of the polyester block copolymer can form a fiber-forming high polymer with only its constituent components, and it is possible to form a fiber-forming high polymer with only its constituent components. A typical example is one mainly composed of an aromatic polyester having a dibasic acid component such as isophthalic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. The average molecular weight of the high melting point crystalline polyester segment in the polyester block copolymer is preferably 400 to 10,000. The low melting point amorphous segment is one that exhibits a substantially amorphous state in the polyester block copolymer (e.g., polyether, aliphatic linear polyester, polylactone, etc., i.e., polyethylene oxide glycol, polytetramethylene oxide glyco). /I/, polyethylene adipate, polyneopentyl sebacate, polyε-cabrolactone, etc. On the other hand, one polymer mixture is polyethylene terephthalate, a mixture of two or more polymers selected from various polyethylene terephthalate copolymers, or a polymer of the above polymer or polymer mixture and a polymer, such as polytetramethylene terephthalate, polyamide, etc. There are mixtures with etc.

In order to maintain the electrical properties, heat resistance, and excellent characteristics of a strong power transmission belt that are generally found in polyethylene terephthalate, a power transmission belt made from a polymer or polymer mixture containing 85 moles or more of ethylene terephthalate component is used. preferable.

Furthermore, additives such as stabilizers, pigments, dyes, and M fuel may be mixed into the polyethylene terephthalate resin depending on the purpose.

To create a power transmission belt from thermoplastic polyester resin, the thermoplastic polyester resin is usually melt-extruded through an annular die, a pressurized gas is sealed inside the tube-bound film, and the resin is simultaneously or sequentially biaxially stretched under pressure. Do -,
A tube-bound polyester film is obtained. The obtained biaxially stretched tube is preferably shaped into a tube or string having an arbitrary length. Creating a ring-shaped body by joining both ends of a flat plate film is inappropriate for manufacturing a transmission belt used in a precision transmission mechanism, which is the object of the present invention.

This is because the thickness and hardness of the joints differ, and unevenness in thickness and unevenness in polishing can cause fatal transmission errors.

Seamless cylindrical polyester film already has excellent properties as a power transmission belt used in small precision power transmission mechanisms, and may be used for this purpose in some cases, but inflation film production is not recommended. The shrinkage treatment of the present invention is used to improve the problem of adverse effects on the smooth transmission mechanism due to creases at both ends that occur during subsequent winding, to maintain the dimensional stability of the transmission belt, or to reduce the creep phenomenon under tension. will be further improved. In the case of polyester films, heat treatment increases their strength.

It is possible to reduce the thickness while maintaining strength.

In the present invention, heat setting is performed while the biaxially stretched tube is heated and shrunk on a cylindrical jig. After cooling, the tubular film on the cylindrical jig is removed from the cylindrical jig using a drawing machine or cut into a predetermined size using a slitter to obtain a conductive belt. The cylindrical jig used in the present invention may be a solid cylinder, an annular shape, an elliptical cylinder, a rectangular cylinder, etc., as long as they meet the purpose.

The technical configuration regarding the heat treatment of the biaxially stretched tube is as follows. That is, the biaxially stretched tube is cut into rings with a length matching the dimensions of the cylindrical jig or slightly longer and mounted on the cylindrical jig. The biaxial stretching tube is
The film is heated to 70°C to 230°C, and at the same time, the outer peripheral surface of the cylindrical body is shrunk to a diameter smaller than the film diameter. The shrinkage rate is usually reduced by within 20%, preferably within 5%.

The longitudinal direction of the film is relaxed by, for example, 0 to 2% or less, and heat set. In this case, the heat treatment time is usually 1 minute to 75 minutes, preferably 15 to 30 minutes at a predetermined temperature. As long as the material of the cylindrical jig has excellent thermal conductivity and has a heat resistance higher than the melting point of the thermoplastic polyester resin,
Although not particularly limited, 1. Iron and aluminum due to machinability and economic efficiency.

Copper or iron-1 alloys such as carbon steel, aluminum alloys,
Copper alloy etc. are used. In addition, those whose metal surfaces are plated with metal such as chrome plating, nickel plating, or zinc, or those whose surfaces are coated with a thin film of Teflon or the like are used.

Next, the biaxially stretched tube after heat treatment was allowed to cool.

Either cut it into a circular shape or pull out the film.

A power transmission belt is manufactured by cutting it to a predetermined length. In this case, if the heat setting temperature is 70° C. or lower, sufficient shrinkage will not occur, resulting in uneven thickness and the strength of the film will not increase. On the other hand, if the heating temperature exceeds 230°C, the film will melt on the surface of the annular body, and the product will not be produced. The optimum heating temperature for the film is in the range of 180 to 220°C.

On the other hand, the diameter of the biaxially stretched tube to be attached is in the range of 1.02 to 1.15 with respect to the diameter of the cylindrical jig, preferably 1.
．． 05-1.10. Usually, the biaxially stretched tube diameter: cylindrical jig diameter is 100:80 to 1 (199, preferably 100:90 to 100:98, but is not limited to this. However, if the shrinkage ratio is too high Shrinkage unevenness may occur during heat treatment, which will significantly increase the film thickness unevenness.If the film thickness unevenness increases, the belt will have uneven hardness, which will impede the transmission mechanism and reduce vibration. This is undesirable because it causes

<Effect of the invention> As described above, the method for manufacturing a conductive belt of the present invention is as follows.

A uniform transmission belt can be easily produced.

The material of the resulting power transmission belt is thermoplastic polyester resin, which has excellent electrical insulation, heat resistance, and high strength, which polyester resin inherently has.

You can obtain a transmission belt with excellent custom features such as:

When the seamless power transmission belt obtained by the above method is used as a drive belt for precision self-recording needles, a power transmission belt for turntables in record players, a separation belt for copy paper in copying machines, etc., it is subjected to extremely long and harsh conditions. It is also durable and shows significant advantages.

<Example> Next, the present invention will be explained in detail with reference to Examples.

Example 1 Polyethylene terephthalate with a relative viscosity of 0.72 was extruded from an annular die to form an outer diameter of 341111. Thickness 1.
I got 1 kaku tube. This tube was bubble-blown stretched 3.3 times in the longitudinal direction and 3.8 times in the radial direction using the inflation method at a furnace temperature of 125°C and an internal pressure of 0.55 kf/CIA. Axial oriented PET
Got tube. This tube has an outer diameter of 135 m and a length of 5
After heat treatment at 220℃ for 20 minutes using an annular jig consisting of a 00mm stainless steel hollow metal tube, the width was 350mm.
A seamless power transmission belt was obtained by slitting M.

Belts ① and ① below were manufactured as comparative samples.

Belt ■: The tip of a biaxially stretched polyethylene terephthalate film (thickness 125μ) was melt-cut to create a jointed belt with a diameter of 12C) asφ1 and a width of 350μ. After heat treatment at 220℃ for 30 seconds with
A belt with slits was manufactured.

The obtained belt ■~0 is used as a transmission belt at a rotational speed of 10
00 Even if you drive it for a long time at r, p, m, it will remain in the driving state.

The durability of the belt was evaluated.

Even after 35 hours of continuous operation, the belt ■ remained extremely smooth and continued to drive without any problems.

Belt ■: Cracks were observed in some joints after 35 hours of driving time. Furthermore, when the driving state of the belt was observed, it was found that the film became thick at the joint of the film, accompanied by a local peripheral speed floor and slight vibration.

B*) O: Pel) K The belt had insufficient heat shrinkage and was extremely uneven, and the drive letter not only vibrated but also clearly rotated.

Patent applicant: Toyobo Co., Ltd.

Claims (1)

[Claims] 1. A method for manufacturing a conductive board A/T, which comprises shrinking a conductive board to the outer surface of a cylindrical jig, then heat-setting and cooling it, and then cutting it to a desired width.