JPS5852092Y2 - heat shrinkable tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a heat-shrinkable tube having excellent properties for closely adhering to the outside of the joint between tubular bodies to form a protective layer.

Conventionally, when connecting tubular bodies, such as metal pipes provided with a plastic anti-corrosion layer, the outside of the joint is coated in order to impart properties such as water resistance, electrical insulation, and anti-corrosion to the joint. It is coated with a heat-shrinkable tube that has excellent adhesion.

This tube has a heat-sensitive or pressure-sensitive adhesive on its inner surface to improve adhesion.

Heat-shrinkable tubes for such purposes include steps due to welding bulges (beads) at the joints of tubular bodies, joints where the lining material has been removed, and areas near the joints where the lining material is covered. It must have the ability to sufficiently fill the level difference.

However, in conventional heat-shrinkable tubes, an adhesive layer is provided on the entire inner surface of the plastic tube, so for example, when a heat-shrinkable tube with a heat-sensitive adhesive layer is used, the adhesive easily flows out of the tube due to the contraction temperature and pressure of the tube, resulting in poor adhesion, and when heated fluid is allowed to flow into the tubular body, there is a risk that the attached tube may be displaced.

Furthermore, if the adhesive is difficult to flow due to heat or pressure, it will not be possible to completely fill the above-mentioned level difference during heating mounting.

Further, even when a pressure-sensitive adhesive layer is used, the adhesive is soft enough to fill the step by heat and pressure when the plastic tube contracts. Similarly, after joining tubular bodies, the adhesive may easily flow out due to heating or external force, resulting in displacement of several tubes, and the adhesive must be sufficiently hard to prevent this displacement. It has been difficult to provide sufficient watertightness and anti-corrosion properties to the joints of tubular bodies with heat-shrinkable tubes of conventional structure, such as the inability to fill the above-mentioned steps.

The present invention was devised to improve this drawback, and has a structure in which only the step portion that occurs at the joint of the tubular bodies is sufficiently filled with adhesive.

That is, the present invention is made by providing a recess of a desired length from the center of the inner surface of a heat-shrinkable rubber or plastic tube toward both ends, and filling the recess with a heat-sensitive or pressure-sensitive adhesive to smooth the inner surface. It is.

Therefore, the heat-shrinkable rubber or plastic tube, which is the basis of the heat-shrinkable tube of the present invention, shrinks when heated and heat-welds to the tubular body, particularly the lining layer of the tubular body, by heating and pressurizing it. For example, crosslinked or stretched plastics such as polyethylene, ethylene-vinyl acetate copolymer, polyester, and polyvinyl chloride, or vulcanized and stretched rubbers such as ethylene propylene rubber, silicone rubber, and chloroprene rubber. is used.

The adhesive layer may be a hot melt type based on ethylene-vinyl acetate copolymer, atactic carbon propylene, asphalt, etc., or a pressure sensitive type based on butyl rubber, natural rubber, NBR, SBR, etc. is used and must flow easily when heated or pressurized.

Also, the reason why the adhesive is filled in the recesses provided from the center of the inner surface toward both ends of the heat-shrinkable tube of the present invention is that even if the tube is repeatedly heated and pressurized, the adhesive flows out from both ends of the tube. This is to ensure that the liquid remains on the inner surface of the tube and maintains the watery properties of the tube.

Note that the length of the recessed portion is not particularly limited, and may be appropriately set depending on the outer diameter of the tube or the purpose of use of the tube.

The structure and function of the heat-shrinkable tube of the present invention will be explained using drawings. Figure 1 is an explanatory cross-sectional view of one embodiment of the heat-shrinkable tube of the present invention, which is made of heat-shrinkable rubber or plastic as a base material. A tube 1 made of The inner surface of the heat-shrinkable tube 1 is flush with the inner surface of the heat-shrinkable tube 1.

Figure 2 shows the heat-shrinkable tube of the present invention as a corrosion-resistant iron pipe 4.4'
This is an explanatory cross-sectional view showing how the tube 1 is mounted on the joint part B of the tube, where the center part A of the tube 1 is dented toward the center due to the heat shrinkage force generated by heating, and this shrinkage force fills the recess on the inner surface of the tube. The adhesive 3 flowing and deforming is cast and filled onto the ends 5, 5' of the anti-corrosion layer, which have been peeled off in advance, and the exposed ends 6, 6' of the anti-corrosion iron pipes 4, 4'. Demonstrates water-like properties.

Note that there is no adhesive on both ends of the heat-shrinkable tube of the present invention, so when adhering these parts to the corrosion-resistant iron pipe, wrap a sheet-shaped heater around the outside of the tube and heat it to a higher temperature than when it shrinks.
By heating the tube under high pressure, for example, at 200° C. for 5 hours, to bond the tube to the anti-corrosion layer, it is possible to impart insulation properties, anti-corrosion properties, and water resistance to the joints of the iron pipes.

In addition, in order to obtain the heat-shrinkable rubber or plastic tube that serves as the base material in the present invention, the rubber or plastic that has been given heat-shrinkable properties in advance is placed on a disassembleable mandrel (such as a tube-type mandrel) having a recess in the center. After wrapping the sheets until the desired thickness is achieved and heat welding them together, the mandrel is dismantled and the formed tube is removed, and the recesses on the inner surface of the resulting heat-shrinkable tube are filled with the desired adhesive. good.

Therefore, a water-retaining metal tube was made by coating the joint portion of the metal tube with a corrosion-resistant layer of Botethylene, respectively, with the heat-shrinkable tube of the present invention made using the same material and the conventional heat-shrinkable tube. After performing a heat cycle at 25 to 90°C in water, it was taken out and cut, and no abnormality was observed in the tube to which the heat-shrinkable tube of the present invention was applied, but the tube to which the conventional heat-shrinkable tube was applied was The layer protruded from the end of the tube, creating a void on the inner surface of the tube, allowing water to enter.

As detailed above, the heat-shrinkable tube of the present invention can be applied to joints of tubular bodies and has remarkable effects such as being able to perform excellent treatments such as insulation, anticorrosion, and watertightness.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of an embodiment of the heat-shrinkable tube of the present invention, and FIG. 2 is a cross-sectional explanatory view showing the shrinkable tube of the present invention when applied to a corrosion-resistant iron pipe. 1... Heat-shrinkable tube, 2... Recess in heat-shrinkable tube, 3... Adhesive, 4.4'
... Corrosion-proof iron pipe, 5°5' ... Corrosion-proof layer end, 6,6' ... Iron pipe end.

Claims (1)

[Scope of utility model registration request] A heat-shrinkable tube, characterized in that a recess of a desired length is provided from the center of the inner surface of the heat-shrinkable rubber or plastic tube toward both ends, and the recess is filled with a desired adhesive to smooth the inner surface.