JPS6039251Y2 - heat expandable article - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in thermally expandable articles.

Heat-expandable articles are used for inner lining of steel pipes, etc.

Therefore, when lining the inner surface of a steel pipe using a conventional thermally expandable tube, the tube must be placed inside the steel pipe to prevent air from remaining between the coating layer and the inner circumferential surface of the steel pipe due to thermal expansion of the tube. After placement, it is desirable to first thermally expand the central portion of the tube, and then proceed toward both ends of the tube, or proceed from one end of the tube to the other.

However, when this conventional product is heated, the entire surface undergoes thermal expansion almost simultaneously, making it difficult to proceed with the thermal expansion process according to the above procedure, resulting in air remaining between the coating layer and the inner circumferential surface of the steel pipe. The phenomenon often occurs.

If air remains between the coating layer made of heat-expandable tube and the inner circumferential surface of the steel pipe, the inner circumferential surface of the steel pipe and the coating layer are not bonded in the area where the air remains, so the coating layer may be damaged by external force. Not only is this easy, but the coating layer may peel off starting from this area.

The present invention relates to a thermally expandable article that solves the problems of the conventional products described above, and is constructed by connecting thermally expandable members having different thermal expansion temperatures.

Thermal expandable members used in the present invention include thermoplastics such as polyethylene, polypropylene, polyvinyl chloride, ethylene-vinyl acetate copolymer, and fluororesin, natural rubber, silicone rubber, butyl rubber, and ethylene-vinyl acetate copolymer.
It is made of rubber such as propylene copolymer or a mixture thereof, mixed with appropriate amounts of additives such as anti-aging agents, fillers, colorants, etc., as desired.For example, these components are mixed uniformly and made into a tube shape, etc. After molding, it is crosslinked if necessary, and then
It is obtained by imparting thermal expandability to the molded article by the method described in Japanese Patent No. 435.

The heat-expandable article of the present invention is made by connecting heat-expandable members having different heat-expanding temperatures, and the difference in heat-expanding temperature between adjacent members is usually about 5 to 150°C, preferably about 10 to 50°C.
Set to 0℃.

Hereinafter, examples of the present invention will be explained with reference to the drawings.

The tubular thermally expandable article shown in FIG. 1 is made from thermally expandable members 1 and 2 having different thermal expansion temperatures.

3 is a pressure-sensitive adhesive provided on the outer peripheral surface of the heat-expandable article;
This is an adhesive layer made of hot melt adhesive, mastic agent, etc.

This heat-expandable article can be obtained by, for example, a method of heat-sealing the ends of two tubes that have been thermally shrunk in the radial direction at different temperatures.

In the thermally expandable article shown in FIG. 1 above, since the thermally expandable members 1 and 2 have different thermal expansion temperatures, they are placed inside a steel pipe,
When heated with a burner, etc., the area with a low thermal expansion temperature expands first, and then the area with a high thermal expansion temperature expands, so air is created between the coating layer made of the thermal expandable article and the inner peripheral surface of the steel pipe. No residue remains, and a satisfactory coating layer can be formed.

FIG. 2 shows another example in which the center part is cut out from the heat expandable member 4 having a low heat expansion temperature, and the heat expansion temperature of both sides is higher than that of the heat expandable member 4, and the heat expansion temperature of both is Approximately equal thermally expandable members 5 and 6 are connected.

When covering the inner circumferential surface of a steel pipe with this heat-expandable article, it is placed inside the steel pipe and heated with a burner, etc., so that the heat-expandable member 4 in the center, which has a lower thermal expansion temperature, first expands thermally, and then Since the thermally expandable members 5 and 6 at both ends thermally expand almost simultaneously, no air remains.

Note that in the example shown in FIG. 2, the thermal expansion temperatures of the thermally expandable members 5 and 6 constituting both ends of the thermally expandable article are approximately equal; You can keep it.

Furthermore, it is also possible to set the thermal expansion temperature to increase successively from one end toward the other end.

The present invention is constructed as described above, in which heat-expandable members having different heat-expansion temperatures are connected, and the heat-expandable members with lower heat-expansion temperatures are sequentially expanded. Air can be prevented from remaining between surfaces.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are both perspective views showing examples of the thermally expandable article according to the present invention. 1, 2.4. 5.6...Thermal expandable member, 3
...Adhesive layer.

Claims (1)

[Scope of utility model registration request] A thermally expandable article formed by connecting thermally expandable members having different thermal expansion temperatures.