JPS588609A - Heat-shrinkable tube - Google Patents

Abstract

PURPOSE:To obtain a heat-shrinkable tube having excellent mechanical strength and also low temperature shrinking properties, by making polycaprolactone of an average molecular weight more than 40,000 a main component, extruding this tubularly and performing electron beam cross-linking, then expanding it. CONSTITUTION:A polycaprolactone of an average molecular weight more than 40,000 is extruded tubularly and the tube is irradiated with an electron beam, crosslinked, then expanded. By this a heat-shrinkable tube which is capable to shrink at a low temperature and also has excellent physical properties of mechanical strength etc. can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a heat-shrinkable tube. Specifically, the main component is polycaprolactone with an average molecular weight of 40,000 or more, which is extruded into a tube shape, then subjected to electron beam crosslinking. , is characterized by being expanded.

Heat shrink tubes are widely used for the purpose of gathering internal wiring, insulating protection of terminal connections, waterproofing protection of thick electrical cables and communication cable joints, and corrosion prevention and protection of pipeline steel pipe joints. It is becoming more and more common.

In general, polyolefin resins such as polyethylene, which have high mechanical strength, are often used.

However, these materials have a high shrinkage start temperature and therefore take too long to shrink.

In addition, a powerful heat source is required, so a gas burner,
-Chilamps etc. are often used.

However, when polyolefin resins are overheated by these heat sources, they have the disadvantage of cracking or burning during shrinkage.

Therefore, the current situation is that there is a demand for a tube that shrinks at a relatively low temperature such as applying heat K, has high mechanical strength, and is resistant to external damage.

Conventionally, rubber tubes, polyvinyl chloride tubes, copolymers or grafted products of ethylene-vinyl acetate copolymers, chlorinated polyethylene, etc. have been used as materials that shrink at low temperatures.

However, for these things that shrink at low temperatures (here, low-temperature shrinkage means that they do not shrink at the constant temperature of 30 to 40 degrees Celsius, but can shrink at temperatures below 100 degrees Celsius (boiling water)), All of them had their advantages and disadvantages, and I didn't like them at all.

In other words, rubber tubes shrink at room temperature, so in order to prevent this, it is necessary to take measures to prevent shrinkage inside or outside the tube.
Difficult to expand (more than twice as much).

Additionally, copolymers such as ethylene-vinyl acetate are generally soft and susceptible to trauma. It has the following drawbacks.

The inventor of the present invention improved the above-mentioned drawbacks of conventional materials for heat-shrinkable tubes, and as a result of studies to obtain a heat-shrinkable tube with excellent mechanical strength and low-temperature accommodation,
As a polycaprolactone with an average molecular weight of 40,000 or more and an average molecular weight of 7 to 10,000 expressed by 900, PLACCEL H-7 manufactured by Daicel Chemical Industries, Ltd. was used, and a tube with an inner diameter of 5 mm, m and a wall thickness of 0.8 fi was used. It was made by extrusion molding.

Next, this tube was irradiated with an electron beam of f 15 Mrad,
After crosslinking, the inner diameter was expanded to about 3 times.

When this expanded tube was poured with hot water at 80 to 100°C, the inner diameter of the tube shrank to 6 m. However, the tensile strength at break was as high as 6 Kf/-, and the mechanical strength was also very superior to that of polyvinyl chloride or other shrinkable tubes that shrink at low temperatures.

The material polycaprolactone has an average molecular weight of 4 to 6.
Similar shrinkage tubes were obtained even when using tens of thousands of tubes, but
Anything less than that could not produce any flavor.

As described above, the present invention was successful in obtaining a heat-shrinkable tube that is shrinkable at low temperatures and has excellent physical properties such as mechanical strength by using polycaprolactone with an average molecular weight of 40,000 or more as a material. In particular, the fact that the tube can be shrunk simply by pouring boiling water on it is a huge advantage in handling the tube, and confirms the high practical value of this invention.

Claims (1)

[Claims] A heat-shrinkable tube characterized in that the main component is polycaprolactone having an average molecular weight of 40,000 or more, which is extruded into a tube shape, then subjected to electron beam crosslinking, and then expanded.