JPS5828354A - Manufacture of thermally shrinkable tube - Google Patents

Abstract

PURPOSE:To obtain a polyamide thermally shrinkable tube which has no forgotten memory of thermal shrinkage and excellent practical utility by emitting and crosslinking a polyamide film by emitting radiation of specific quantity, then sequentially orienting and fusing the film. CONSTITUTION:40-60 Mrad of radiation is irradiated to a polyamide film having 0.01-0.5mm. of thickness, thereby crosslinking the film. Thereafter, the film is oriented at the prescribed temperature (normally at 140-150 deg.C), the orienting state is maintained and the film is quenched, thereby imparting thermal shrinkage to the film. An ageing preventing agent and a colorant may be added and mixed with the film. After the film is wound on a refractory core made of metal or refractory plastic or the like, the film is heated to a temperature higher than the softening point of the film, thereby bonding the films. After the film is cooled, the core is removed, thereby obtaining a thermally shrinkable tube which has no forgotten memory of thermal shrinkage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing polyamide F to M, b heat-shrinkable cheapo.

Conventionally, heat-shrinkable dyes such as polyethylene,
Although ethylene-vinyl acetate copolymer or ethylene-propylene copolymer rubbers are used in industry, heat-shrinkable rubber made from polyamide is based on the properties of polyamide. However, if the heat shrinkage is small due to the increase in #Ik during use compared to the heat shrinkage rate imparted by stretching, it will cause "forgetting to remember" the shrinkage in places. − is not obtained.

The present invention relates to a method for manufacturing a useful shrinkable polyamide film that does not forget the memory of heat shrinkage. After crosslinking and stretching, the polyamide film is given heat-shrinkability, and then this heat-shrinkable polyamide film is wrapped around a thermal core and heated. This method is characterized in that the core is removed after the ilms are fused together.

In the present invention, first, the thickness is 0. O1~0.6111@
Radiation such as electron beam is applied to the polyamide film of 40 to 6 degrees.
The film is cross-linked by irradiation with 0 megarads, and then this film is stretched at a predetermined temperature (usually at 140-150 °C), and heat shrinkability is imparted by rapidly cooling the stretched film while maintaining the stretched shape S. be done. Radiation dose is 40
If it is less than 60 megarads, a heat-absorbing chip with no memory of heat shrinkage will not be obtained, and if it is more than 60 megarads, the hardness of the polyamide film will increase and the stretching operation will be @@1clk, so the h deviation is also unfavorable. . The polyamide film may contain appropriate amounts of additives such as anti-aging agents, colorants, and fillers.

J1flk contractile bonoami F obtained as above
The film is then made of metal, ceramics, or a heat-resistant plastic such as a fluororesin, and is then wound a predetermined number of times on a heat-resistant core such as a cylinder or a rod by winding or helical winding. Above the softening point (3111190~2
20° C.) to fuse the films together. At this time, the KFP is set according to the heating temperature, the strength of the film, the number of times the film is wound, etc., but it is usually 10
It took about 4.0 minutes.

In this way, the heat-shrinkable polyamide films wrapped around the heat-resistant core are fused together and cooled, and the core is removed. A shrinkable chip can be obtained. When heat-shrinkable polyamide films are fused together, if a core having a larger thermal expansion coefficient than the polyamide film is used, the strength of the fusion between the films can be increased. This is preferable because it further improves.

In addition, if the heat-resistant core is made of metal and does not have removability by itself, apply a release agent such as silicone resin or fluororesin to the outer circumference, or apply a fluororesin sheet to the outer circumference. Peel it off by wrapping it around and fixing it. It is preferable to carry out the treatment because it makes it easier to remove the core after fusion.

The present invention has been modified as described above, and a polyamide film is crosslinked by irradiating a specific amount of radiation*, then stretched,
By sequentially performing fusion bonding, it is possible to obtain a heat-shrinkable polyamide cheap that is highly practical and has no memory of heat shrinkage.

Hereinafter, the present invention #4t will be described in more detail with reference to Examples.

EXAMPLE A long meliamid film (manufactured by Daicel Chemical Co., Ltd., trade name: DIALD) having a thickness of 0.3 M and a width of 600111 mm was crosslinked by irradiating it with an electron beam of 50 megarads.

The cross-linked long polyamide film was stretched 70 inches in the longitudinal direction at a temperature of 150°C and then quenched at L7.
A heat-shrinkable polyamide film having a heat shrinkage rate of 70% in the longitudinal direction is obtained.

Next, this heat-shrinkable polyamide film was wrapped three times around a soft pipe with an outer diameter of 5 mg, the outer circumference of which had been peeled off by applying silicone resin, so that the longitudinal direction was along the outer circumference of the pipe, The end of the roll was temporarily attached with adhesive tape to prevent it from unrolling, and placed in a heating oven maintained at 200°C for 40 minutes to bond the films together. After IM, it is taken out from the heating furnace and cooled, and the iron pipe is placed in the gap.
A polyamide heat-shrinkable cheapo having an inner diameter of 87 mm and a thickness of 41 H% and a length of 600 m was obtained.

In order to find out the heat shrinkage rate of this mature shrinkable cheep in the radial direction, the cheep was left in a heating furnace at 200°C for 10 minutes in the heat-shrinkable autumn spring, and the heat shrinkage rate was measured.
It was a song that I will never forget.

For comparison, all the work was carried out in the same manner as above except that the electron beam irradiation amount was set to 30 and 70 megarads, and when the electron beam irradiation was set to 70 megarads,
The polyamide film broke and broke during stretching, and it was not possible to achieve low shrinkage. Also, the amount of electron beam irradiation? : Heat-shrinkable breath obtained when using 30 megarads
The thermal shrinkage rate in the radial direction of the tube was only 3 degrees, which could cause memory loss.

patent applicant Nitto Electric Industry Co., Ltd. Representative Sanbe Hijikata

Claims (1)

[Claims] A polyamide film is irradiated with radiation of 40 to 50 megarads to cross-link it, and then stretched.The polyamide film is given heat-shrinkability, and then this heat-shrinkable polyamide film is placed on a heat-resistant core. Wrap it around and heat it,
A method for manufacturing a heat-shrinkable chimney in order to make the core body (t-**) into camphor mold after fusing the films together.