JPS5954022B2 - composite pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite pipe in which a vinyl chloride resin layer is provided within a metal pipe via a polyurethane foam layer.

Previously, Utility Model Application No. 50-350877 or Utility Model Application No. 5
As disclosed in Japanese Patent No. 2-113221, a composite pipe is known in which a foam layer of soft or hard polyurethane resin is interposed between a metal pipe and a general synthetic resin pipe.

However, as mentioned above, when using general synthetic resin pipes, the adhesion between the synthetic resin pipe and the foam layer is not sufficient, so when a fluid that is repeatedly heated and cooled is passed through the composite pipe, the metal pipe becomes Due to the difference in coefficient of thermal expansion from the synthetic resin pipe, the synthetic resin pipe gradually shrinks in the axial direction, resulting in an undesirable part where the synthetic resin pipe does not exist at the end of the metal pipe. The present invention was made for the purpose of solving the above-mentioned conventional drawbacks, and its gist is that a vinyl chloride resin pipe is inserted into a metal pipe, and a polyurethane foam layer is provided between both pipes. , a composite pipe in which both pipes are fixed by the polyurethane foam layer, characterized in that the vinyl chloride resin pipe contains an alcohol-based lubricant. As the metal tube used in the present invention, for example, what is generally called a metal tube such as a steel tube, a stainless steel tube, or a steel tube can be used. 100mm to 100
0 type is preferably used.

The vinyl chloride resin pipe used in the present invention has a gap of 0.2 m between the outer diameter and the metal pipe when inserted into the metal pipe.
A material having a diameter of m to 2 mm is preferably used.

Examples of the polyurethane foam used in the present invention include polyols such as polyether, polyol, and polyester polyol, and organic diisocyanates such as tolylene diisocyanate, diphenylenemethane 4-4'di-1-isocyanate, and prepolymers thereof. A polyurethane foaming liquid mixed with a small amount of a blowing agent, a catalyst, etc. is used.

Note that polyurethane foams having a density of 0.1 or more are preferably used because they have strong adhesive strength. θ Alcohol-based lubricants used in the present invention include, for example, monohydric alcohols such as stearyl alcohol and decyl alcohol, dihydric alcohols such as ethylene glycol, glycerin, monoesters of pentaerythritol, and mono- and diesters of diventaerythritol”5. , polyhydric alcohol such as polyethylene glycol (molecular weight 100 to 2000) is used.The amount of alcohol-based lubricant in the vinyl chloride resin pipe in the present invention is 0.00 parts by weight per 100 parts by weight of the vinyl chloride resin.
1 to 20 parts by weight is preferably used.

When an alcohol-based lubricant is put into the PVC pipe, the alcohol-based lubricant having hydroxyl groups on the surface of the PVC pipe is exposed in a chemically bonded state with the PVC resin, and the surface of the PVC pipe is exposed. is surface-activated with an alcohol-based lubricant to improve adhesion to the urethane foam layer. Hereinafter, the present invention will be explained by way of examples with reference to the drawings. 1 is a metal pipe such as a thin-walled steel pipe, and 2 is a vinyl chloride resin pipe containing an alcohol-based lubricant.

A stock solution selected from the polyurethane foaming liquids described above is applied to the inner circumferential surface of the metal tube 1 or (and) the outer circumferential surface of the vinyl chloride resin tube 2 as appropriate to 1/2 of the gap between the metal tube 1 and the vinyl chloride resin tube 2.
PVC resin pipe 2 is placed inside metal pipe 1.
is inserted, the stock solution is foamed and hardened between both tubes, a polyurethane foam layer 3 is provided between both tubes, and a composite tube is obtained in which both tubes are fixed by the polyurethane foam layer 3.
2. However, when a fluid that repeatedly heats and cools is passed through the composite tube of the present invention as described above, the vinyl chloride resin tube does not shrink in the axial direction. Example metal tube: outer diameter 114.3 mm, inner diameter 105.3 mm
, Using a steel pipe with a length of 24 m, a vinyl chloride resin pipe with an outer diameter of 103.3 mm, an inner diameter of 95.3 mm, and a length of 4 m was formed by adding 5 parts by weight of stearyl alcohol to 100 parts by weight of vinyl chloride resin. Using.

As a result, there was a gap of 1.0 mm between the two tubes. As the polyurethane foam liquid, a semi-rigid polyurethane stock solution having the following composition (parts by weight) was used.

While rotating the vinyl chloride resin tube, the above stock solution was applied to the outer surface of the vinyl chloride resin tube to a thickness of 0.5 mm, and this was advanced and inserted into the metal tube.

When inserting, in order to maintain a uniform gap of 1 mm between both tubes, a PVC resin rod with a diameter of 1 mm and a length of 30 mm is placed on the outer surface of the PVC resin tube along the tube axis direction. This was used as a gap retaining material. After inserting the vinyl chloride resin tube in this manner, hot air at 70° C. was applied to the outer surface of the metal tube to heat the metal tube. As a result, the stock solution was rapidly foamed and hardened, and a composite tube in which both tubes were fixed by the foam layer was obtained. This composite tube is heated (70℃) and cooled (
15° C.) was repeated (24 cycles per day), and the state of contraction in the axial direction of the vinyl chloride resin pipe was measured. The results are shown in Table 1. For comparison, 5 parts by weight of paraffin-based lubricant was added to 100 parts by weight of vinyl chloride resin as a vinyl chloride resin pipe.
A composite tube was made according to the above-mentioned example using a product molded by adding parts by weight, and the same heating and cooling test as above was conducted.

The results are also shown in Table 1. As is clear from Table 1, in the case of composite pipes using vinyl chloride resin pipes containing alcohol-based lubricants as in the examples of the present invention, the shrinkage of the vinyl chloride resin pipes in the axial direction due to heating and cooling is slight. be.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention. Explanation of symbols 1...metal body, 2...vinyl chloride resin pipe, 3...urethane foam.

Claims (1)

[Scope of Claims] 1. In a composite pipe in which a vinyl chloride resin pipe is inserted into a metal pipe, a polyurethane foam layer is provided in both pipes, and both pipes are fixed by the urethane foam layer, the chloride resin pipe is A composite pipe characterized in that the vinyl resin pipe contains an alcohol-based lubricant. 2. The composite pipe according to claim 1, wherein the polyurethane foam layer has a density of 0.1 or more.