JPS5843250B2 - Polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing polyester coated metal rods.

More specifically, it is a method for producing a polyester-coated metal rod, which comprises covering the metal rod with a biaxially oriented polyethylene terephthalate-based polyester heat-shrinkable tube or tubular body and maintaining the metal rod in an atmosphere at a specific temperature for a specific period of time. By this method, it is possible to easily produce a polyester-coated metal rod with excellent workability, in which the coating does not shrink due to heat generated during cutting or drilling.

BACKGROUND ART In order to impart corrosion resistance or aesthetic appearance to metal rod-shaped objects such as metal tubes or metal rods, they are coated with polymers.

As a simple means of covering a metal bar, it is known to cover the metal bar with a heat-shrinkable tube or a tubular body and shrink the metal bar by heating.

The heat-shrinkable tube or tubular body used for the coating is preferably a polyester heat-shrinkable tube or tubular body based on polyethylene terephthalate because of its toughness, chemical resistance, heat resistance, etc.

However, in many cases, metal rods, such as metal tubes, are processed by cutting or perforating them, and these processing operations are indispensable for the use of metal rods.

For example, due to the heat generated during cutting, the cut portion becomes hot, especially in the case of thick-walled pipes.

However, since polyester heat-shrinkable tubes or tubular bodies are produced by highly biaxial stretching, although they are heat-shrinked and tightly coated on metal rod-shaped bodies,
Since it is highly biaxially oriented, there is a drawback that the coating film near the cut portion contracts due to heat generated during processing such as cutting, and the metal surface at the end portion is exposed.

Therefore, it is desired to manufacture a metal rod-shaped body covered with a polyester heat-shrinkable tube or tubular body so that the coating film does not shrink due to heat generated during cutting.

The present inventors attempted to overcome the above-mentioned difficulties of a metal rod-shaped body coated with a biaxially oriented polyethylene terephthalate-based polyester heat-shrinkable tube or tubular body, and the inventors of the present invention have attempted to overcome the above-mentioned difficulties of a metal rod-shaped body coated with a biaxially oriented polyethylene terephthalate-based polyester heat-shrinkable tube or tubular body. It has been discovered that a polyester-coated metal rod with the desired performance can be efficiently obtained by exposing the metal rod covered with polyester for a specified period of time or longer.

That is, the present invention is characterized in that a metal rod-shaped body covered with a biaxially oriented polyethylene terephthalate heat-shrinkable tube or tubular body with a thickness of 50 to 200 μ is kept in an atmosphere at a temperature of 300° C. or higher for 5 seconds or more. This is a method for producing a polyester-coated metal bar.

The polyethylene terephthalate heat-shrinkable tube or tubular body referred to in the present invention refers to a heat-shrinkable tube or tubular body mainly composed of polyethylene terephthalate, that is, a polyethylene terephthalate copolymer containing about 20 moles or less of polyethylene terephthalate and a copolymer component. Union,
Or a biaxially oriented heat-shrinkable tube or tubular body made from a mixture of these polymers, for example, preferably by extruding the polymer into a tubular shape from an extruder equipped with an annular die, cooling it, and winding it up. It is produced by injecting pressurized gas from the end of the obtained unstretched tubular body to expand and stretch it 3 to 5 times in the radial direction through a heating zone, and at the same time stretching it 3 to 5 times in the axial direction using differential speed rolls.

Polyester heat-shrink tubes or tubing may contain various additives such as pigments, dyes, metal powders, matting agents, flame retardants, antioxidants, UV stabilizers, fillers, lubricants and some amount of other polymers. etc. may be added.

The metal rod-shaped body referred to in the present invention is a metal tube or metal rod made of steel, stainless steel, aluminum, etc., and has a circular, polygonal, or irregular cross section, and can be tightly packed by covering it with a heat-shrinkable tube and heating it. As long as it has a cross section with a shape that can be covered, it has the same thickness.
It may be tapered or deformed.

In order to cover a metal bar with a polyester heat-shrinkable tube or tubular body, the heat shrinkability of the inner periphery must be approximately 1.03 to 1.1 times larger than the outer periphery of the metal bar for operational reasons or appearance after heat shrink treatment. Preferably, tubes or tubular bodies are used.

A metal rod covered with a polyester heat-shrinkable tube or tubular body is passed through a heating range of, for example, 150 to 220°C, so that the metal rod is tightly coated. Due to intense heat generation during cutting, shrinkage of the coating film near the cut area is unavoidable.

By keeping the metal rod-shaped body covered with a polyester heat-shrinkable tube or tubular body in a high-temperature atmosphere of 300°C or higher, preferably 320°C or higher, it is possible to obtain a coated metal rod-shaped body in which the coating film does not shrink during practical cutting. can be obtained efficiently.

For example, when a polyethylene terephthalate heat-shrinkable tube with a wall thickness of 100μ is placed over a steel pipe with an outer diameter of 13M and a wall thickness of 1, and held in a high-temperature atmosphere, the time required to achieve the desired effect is 40 seconds at an ambient temperature of 350℃. Good but 30
The effect decreases rapidly at temperatures below 0°C, for example at 250°C.
Even if it is held for 5 minutes, it is still insufficient.

If the atmosphere becomes too high, thermal decomposition of the polyethylene terephthalate polymer will become noticeable, so the ambient temperature should be set at 50℃.
The temperature is preferably 0°C or lower, and it is not desirable to exceed 700°C.

The holding time can be shortened by increasing the temperature of the atmosphere, but in order to give a uniform thermal effect to the coating and obtain a good appearance,
The holding time is required to be 5 seconds or more, preferably 20 seconds or more.

Preferably, a metal rod-shaped body is covered with a polyethylene terephthalate heat-shrinkable tube or tubular body having a thickness of about 50 to 200 μm, or a metal rod-shaped body is heat-shrinked in advance and covered tightly, and passed through a cylindrical electric furnace, or Heat treatment is performed through an atmosphere at a temperature of 300° C. or higher using means such as infrared heating.

These operations can be performed continuously or in portions.

According to the method of the present invention described above, a coated metal bar can be manufactured with a simple operation as long as there is a metal bar, a polyethylene terephthalate heat-shrinkable tube or tubular body, and a heat source. There is no problem of pollution caused by various solvents, and the resulting coated metal bar does not have problems such as shrinkage of the coating due to processing such as cutting or drilling.The coating is strong and durable due to the excellent properties of polyethylene terephthalate resin. It has excellent corrosion resistance, so it can be used for furniture,
Suitable for a wide range of applications such as office equipment and building materials.

The present invention will be explained in more detail below with reference to Examples.

Example 1 Melt extrusion using polyethylene terephthalate pellets,
Diameter 13.8 pairs, thickness 75, created by two-axis orientation operation
μ heat-shrinkable tube with an outer diameter of 13M.

It is placed over a steel pipe with a wall thickness of 111g1, and the atmospheric temperature in the central space is set to 3.
The tube was heat-shrinked by passing through a cylindrical electric furnace having a length of 40 crrL and an inner diameter of 8 cfrL maintained at 50° C. at a speed of 0.56 m/min to tightly coat the steel pipe.

The obtained coated steel pipe was cut on a high-speed rotating grindstone at a rotation speed of 2400/min, but no shrinkage of the coating at the cut portion was observed.

The coating is tough, with a breaking strength of 19.5 Ky/c.
yyt, and the elongation at break was 122%.

For comparison, when a coated steel pipe made in the same manner as above was cut at an electric furnace ambient temperature of 270°C, the coating at the cut point shrank and the steel fabric was exposed, so the cylindrical electric furnace was heated at a rate of 0.28°C per minute.
Although the holding time was doubled, shrinkage of the film still occurred due to cutting.

Example 2 A biaxially oriented heat-shrinkable tube was prepared by blending 0.5% by weight of a yellow pigment (Pigment Yellow 4610 manufactured by Ciba Corporation) with polyethylene terephthalate containing 10 mol □ of neopentyl glycol as a copolymerization component.

This heat-shrinkable tube with a diameter of 13.9w1 and a wall thickness of 100μ was placed over a pair of aluminum tubes with an outer diameter of 1sm and a wall thickness, and the tubes were shrunk at about 150°C, and then arranged in series at an ambient temperature of 400°C and a length of 40cm. , three cylindrical electric furnaces with an inner diameter of 8 crrL were passed through at a speed of 0.15 m/min, and water was poured immediately after the exit of the last electric furnace for cooling.

The resulting beautiful yellow coated aluminum tube showed no shrinkage of the coating during cutting.

Since the coating is heat-treated at a high temperature for a sufficient period of time, the coating is firmly fused and bonded to the aluminum, and no cracking or peeling of the coating is observed even when the cladding tube is bent at right angles.

Example 3 The polyethylene terephthalate heat-shrinkable tube of Example 1 was placed over a steel pipe with an outer diameter of 13M and a wall thickness of 17II111 to a length of 40crIL1 and an inner diameter of 8cIf1. The coated steel pipes were passed through a cylindrical electric furnace at different speeds of 1.20 m, 2.40 m, and 8.0 Om per minute to obtain coated steel pipes.

The atmospheric temperature inside the furnace was 650°C.

The examples of the present invention, 1.20-7L per minute (furnace residence time 20 seconds) and 2.4 om per minute (furnace residence time 10 seconds), have good appearance, but the comparative example min 8.0
In the case of 0 m (furnace residence time of 3 seconds), wrinkles appear on the surface and the appearance is poor.

For 1.20 m/min and 2.40 m/min, rotation speed 2
When cutting with a high-speed rotating grindstone at 4 QO/min, no shrinkage of the coating occurred.

Claims (1)

[Claims] A polyester-coated gold layer characterized by keeping a gold layer rod-shaped body covered with a 12-axis oriented polyethylene terephthalate heat-shrinkable tube or tubular body with a thickness of 50 to 200 μ in an atmosphere at a temperature of 300° C. or higher for 5 seconds or more. Method for manufacturing rod-shaped bodies.