JPS6058833A - Thermal treatment of heat shrinking film - Google Patents

Abstract

PURPOSE:To achieve a shrink packing evenly and with extreme ease using a heat shrinking film by supplying water to the bottom of a special thermal treatment chamber to evaporate it instantaneously. CONSTITUTION:A small amount of water is supplied from a water feed port 11 on the bottom 10 of a thermal compression chamber 6 which has one or more through openings 7 horizontally while the other parts thereof are made up of walls heatable above 100 deg.C internally. A product covered with a heat shrinking film, for example, a polyvinyl chloride tube is inserted through the opening 7 and then the water is evaporated instantaneously in combination with heat of heated air to perform a thermal shrinking treatment evenly and with extreme ease.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for uniformly heat-treating and shrinking an article packaged with a heat-shrinkable film.

It is common practice to wrap articles of irregular shape using a heat-shrinkable film made of synthetic resin such as polyvinyl chloride or polyethylene, and pass it through a heat-shrink tunnel, during which time hot air is applied to create a taut package. It's coming.

However, when using this tunnel, a hot air generator,
Since a hot air circulation device and the like are required, the heat shrinking device inevitably has the disadvantage of being easily destroyed.

Furthermore, since air has poor thermal conductivity, the film tends to shrink unevenly.

The inventors of the present invention investigated how to solve the inconvenience of heat treatment using heated air, and found that they used a heating chamber that instantaneously evaporates water when it is supplied, and the heat shrinkage is mainly caused by the generated water vapor. The present invention was completed based on the discovery that heat shrinkage can be achieved extremely easily and uniformly by carrying out this process.

That is, the gist of the present invention is to provide an article packaged with a heat-shrinkable film inside a heat treatment chamber that has one opening or a penetrating opening in the horizontal direction, and the other part has an inner wall that can be heated to 100°C or higher. The heat-shrinkable film is heat-treated by supplying a small amount of water to the bottom of the heat-treating chamber and instantaneously evaporating the film when the film is heat-shrinked.

The present invention will be explained below using the drawings.

Figure 1 shows polyvinyl chloride pipe (1) and fire-resistant cladding pipe (2).
In order to prevent separation between the two tubes and to protect the ends of both tubes when the two tubes are fitted to the outside with the former protruding from the outside, the ends are previously covered with a tube (3) of heat-shrinkable polyvinyl chloride film. A vertical cross-sectional view is shown when the part is covered. The length of the tube is selected to be such that when it is shrunk, it covers from the refractory cladding tube end (4) to the polyvinyl chloride tube end (5).

Here, the use of the polyvinyl chloride pipe fitted with the fire-resistant cladding, the necessity of heat-shrink packaging, etc. will be explained.

The above-mentioned polyvinyl chloride pipes are used as they are for water supply, drainage, and ventilation within buildings, but if these pipes are shared across each room of a high-rise building or a number of compartmentalized rooms, there is a risk of fire, etc. If this happens, flames and toxic gases will be guided into each room through these pipes, potentially endangering human life. As a countermeasure against this problem, recently, a combination pipe with the above-mentioned fire-resistant cladding whose main component is cement etc. has been developed and has been well received. Since the fireproof cladding tube may be damaged due to thermal expansion of In order to prevent this, methods have been taken such as driving a cracker into the gap or interposing a small piece of foam, but this has been seen as a problem as it tends to damage the fire-resistant cladding.

Regarding this point, the present applicant has proposed a method to prevent the separation of both pipes when a slightly short and small fire-resistant cladding pipe is slidably fitted onto the polyvinyl chloride pipe, and to improve the fire-retardant cladding during storage or transportation. In order to protect especially the ends of the cladding tube, we proposed shrink-wrapping the ends of the cladding tube and the protruding polyvinyl chloride tube with a heat-shrinkable film.

Although the method according to the present invention can be applied to heat shrink packaging described in Section 2, it goes without saying that it can also be used for heat shrink packaging of foods, miscellaneous goods, etc., and the present invention is not limited in any way by the object of heat shrink wrapping. It is not something that is received.

The tube end in the state shown in FIG. 1 is inserted into the heat shrink chamber (6) through its opening (7) as shown in FIG.

Thermal acid chamber 1ii has a horizontal cylindrical part (8) and a vertical wall part (9).
and a water supply port provided at the bottom (10) of the horizontal cylindrical part.
(11), and the cylindrical part (8) and wall part (9) have jackets (12) into which high-temperature, high-pressure steam can be introduced, and the inner surface is made of metal and is not in a heat-insulated state. High-temperature, high-pressure steam is introduced into the jacket through a pipe (13) and heats the inner surface of the heat-shrinking chamber, while the drain is taken out through an exhaust pipe (14).

When the polyvinyl chloride pipe covered with the heat-shrinkable film and fitted over the fire-resistant cladding is inserted through the opening in the lateral direction, the heat shrinks due to radiant heat from the wall of the heat-shrinkable chamber or heat from the heated air inside the heat-shrinkable chamber. Heat-shrinkable film shrinks to some extent, but
A small amount of water supplied from the water supply port evaporates at the same time as it spreads to the bottom of the heat shrink chamber, and the generated high-temperature steam does not condense because the outer periphery is surrounded by a heating wall. Since the heat-shrinkable film is generated at the bottom and rises in the enclosed room, it tends to spread uniformly over the entire heat-shrinkable film, so that the heat-shrinkage also occurs uniformly.

FIG. 3 shows a longitudinal cross-sectional view of the heat-shrinked state.

(15) shows the film after heat shrinkage. The amount of water to be supplied is determined based on the state of heat shrinkage; if it is too large, it will not evaporate instantaneously and high-temperature steam will not be obtained, but will also undesirably cool the bottom of the heat shrink chamber. Since the bottom surface is cooled by the latent heat of the evaporation of the supply water, it is heated again and the above-mentioned heat shrinking operation is repeated in consideration of the period until the temperature returns to the original temperature.

Typical heat-shrinkable films are made of polyvinyl chloride or polyethylene, but polyester, polypropylene, polyvinylidene chloride, etc. are also commercially available, and these films can reduce the temperature of the inner wall of the heat-shrinking chamber. All can be effectively utilized by adjusting.

All of the above explanations have been made regarding a heat shrink chamber having one opening in the horizontal direction. However, when the articles to be heat shrink wrapped are sequentially brought in by a chain conveyor, etc., an opening that passes through the horizontal direction is used. A heat shrink chamber with a

Water is preferably supplied from the bottom of the heat shrink chamber so that it is distributed as widely as possible over the bottom. FIG. 4 shows one embodiment for this purpose, in which the supplied water (16) is widely spread over the bottom (10) by the baffle plate (17), allowing it to evaporate faster and over a wider area.

Example A stainless steel heat shrink chamber with an inner diameter of 300 m+n and a jacket capable of passing high-pressure steam around the entire outer periphery and open only on one side was used.
of water vapor was introduced, and the drain was taken out from the bottom of the jacket. The inner surface of the heat shrink chamber was adjusted to 110 to 120°C.

On the other hand, the inner diameter of the polyvinyl chloride inner tube with an outer diameter of 114 mm is
A fire-resistant cladding tube (outer tube) mainly composed of cement with a diameter of 14.5 mm and an outer diameter of 132 mm is fitted onto the outside leaving 50 mm at the inner tube end, covering the inner and outer tube ends and covering the inner tube end. Extrapolate the polyvinyl chloride heat-shrinkable film with a diameter of 137!0111, which has been extended by 20 mm, and insert that part into the heat-shrinking chamber, and when it has slightly shrunk, pour about 50 g of water from the bottom of the heat-shrinking chamber. and sprinkled on the bottom. The water evaporated immediately and the polyvinyl chloride film could completely and tightly wrap the inner and outer tube ends, and there was no mutual movement between the inner and outer tubes.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the heat-shrinkable film inserted into the required part of the tube, Figure 2 is a vertical cross-sectional view of the heat-shrinkable film inserted into the heat-shrink chamber, and Figure 3 is the heat-shrinkable film. FIG. 4 is a vertical cross-sectional view of the film in a heat-shrinked state, and FIG. 4 is a vertical cross-sectional view of an example of the vicinity of the water supply port. Patent applicant: Showa Denko Co., Ltd. Representative: Sei Kikuchi −

Claims (1)

[Claims] An object wrapped in a heat-shrinkable film is placed in a heat treatment chamber that has one or a penetrating opening in the horizontal direction, and the other part is a wall whose inner surface can be heated to more than io ``a''. 1. A method for heat treatment of a heat-shrinkable film, characterized in that when heat-shrinking the film, a small amount of water is supplied to the bottom of the heat treatment chamber and instantaneously evaporated.