JPS6090737A - Inner covering material for tubular product - Google Patents

Abstract

PURPOSE:To line the inner surface of a steel tube with an expanded covering layer by a simplified method in which a covering material formed by housing a curved resilient metal thin plate in the inside of a heat-expansible tubular material is inserted into the steel tube and expanded by heating. CONSTITUTION:A curled resilient metal thin plate 2 is housed on the inside of a heat-expansible tubular part 1 made of polyethylene mixed with a blowing agent to form a covering material. The covering material is inserted into the aperture 6 in a steel tube to be lined for its inside and heated to cause the tubular part 1 to expand, and the tubular part is pressed on the inner surface of the steel tube by the metal thin plate 2 to closely bond the tubular part to the inner surface of the steel tube for convering. The metal thin plate 2 is then pulled out of the steel tube 3. The lining of the inside of the steel tube can thus be simply attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating material for forming a foam coating layer on the inner surface of a tube-shaped article such as a steel pipe.

In recent years, urethane 7 has been used on the inner surface of steel pipes for transporting fluids such as gas and water.
Polymer foams such as ohms are coated to provide functions such as heat insulation, heat retention, and buffering properties.

Conventionally, as a practical example of this type of inner surface coating method, a method is known in which a pre-foamed polymer molded product in the form of a crystalline polymer is drawn into a steel pipe. However, with this method, the adhesion strength between the formed body and the inner surface of the steel pipe is not sufficient, and the formed body may be misaligned within the steel pipe, and it is difficult to produce a formed body whose outer diameter corresponds to the inner diameter of the steel pipe. There is the inconvenience that molds of various sizes are required.

For this reason, a method using a so-called "thermally expandable cheap" which expands greatly in diameter upon heating, or a lining method using a liquid resin have been considered, but the reality is that they are not yet satisfactory.

The present invention relates to an inner surface coating material for a tube-shaped article that solves the problems of the prior art, and includes a tube-shaped member that can be foamed by heating, and a tube-shaped member that is curved along the inner wall surface of the tube-shaped article and has rebound resilience. The present invention provides a covering material made of a thin metal sheet.

The cheap member in the present invention is a thermoplastic synthetic resin such as polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, polyvinyl chloride, ethylene-acrylic acid copolymer, ethylene-ethyl acetate copolymer, or natural rubber. , synthetic rubber or a mixture thereof, an azo compound such as azodicarbonamide, azobisisobutyronitrile, nitrosated 6m such as dinitrosopentamethylenetetramine, paratoluenesulfonyl hydrazide, 4
・Blending a blowing agent such as a sulfonyl hydrazide compound such as 4-oxybisbenzenesulfonyl hydrazide 1. It is formed into a cheap shape.

The amount of the foaming agent can be determined as appropriate depending on the expansion ratio of the coating layer to be formed on the inner surface of the tube-shaped article, but it is usually about 1.5 parts by weight of the resin or rubber. The amount is 2 to 15 parts by weight.

If desired, suitable amounts of foaming aids such as urea and metal salts of carboxylic acids, fillers, colorants, anti-aging agents, stabilizers, etc. can be added.

This cheep-shaped member can be produced, for example, by a method in which the above ingredients are uniformly kneaded, pelletized using a pelletizer, and then melt-extruded into a chive-like shape under temperature conditions that substantially prevent the decomposition of the blowing agent, or by the method described above. Similar pellets can be obtained by melt-extruding them into a sheet under temperature conditions that substantially inhibit the decomposition of the blowing agent, and then heat-sealing both ends of the sheet to form a cheap shape.

In the present invention, the inner surface of the tube-shaped member is made of thermoplastic resin 11L, which does not flow at the foaming temperature of the member, such as polyethylene, ethylene-vinyl acetate copolymer, or ethylene-acrylic acid copolymer. A protective layer consisting of , ethylene-ethyl acetate copolymer, etc. (cross N1° may be used if desired) can be formed, and such an inner coating material can provide functions such as waterproofness and moisture-proofing properties. .

In addition, a thin metal plate and 1. In this case, steel plates, stainless steel plates, etc., which can be deformed into a curved shape and which exhibit rebound elasticity when the force applied during deformation is released, are used, and the thickness is 11.1.
About 15 to 0.5 fl is practical.

Next, the present invention will be explained in detail with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 is a chive-shaped member that can be foamed by heating, and a thin metal plate 2 is curved and housed along the inner wall surface of the member. being admired. This thin metal plate 2 does not cause the chevron-shaped member 1 to undergo extreme deformation or breakage at room temperature, and when the chevron-shaped member 1 is softened or melted by heating, it is radially outward in the entire radial direction of the chevral member 1. It is curved so as to have rebound elasticity that allows it to be extruded relatively gently.

1. In order to coat the inner surface of a steel pipe with the inner surface coating material of the tube-shaped article according to the present invention, for example, as shown in FIG. The tube is inserted, and then heated from the thin metal plate 2 side and/or the outer peripheral surface side of the steel pipe 3 using a gas burner, electric heater, induction heating, or the like.

By this heating, the volume of the tape-shaped member 1 expands due to the decomposition and foaming of the foaming agent contained therein, filling the space 6 between the inner surface of the steel pipe 3 and the inner periphery of the copper pipe 3 due to the repulsive elastic force of the thin metal plate 2. Pressed against the surface. Due to the synergistic effect of the volumetric expansion force due to the decomposition and foaming of the foaming agent and the repulsive elastic force, the softened or melted hand-shaped member l firmly adheres to the inner surface of the steel pipe 3, and the fourth Foam covering layer 4 as shown in the figure
is formed. The foaming ratio of this foamed coating layer 40 may vary depending on the foaming agent content, the pressing force of the thin metal plate, etc., but it is generally about 2 to 15 times (measured according to JIS K-6767, foaming ratio = 1/apparent density of foamed coating layer). ) is better.

In the present invention, an adhesive layer such as a hot melt adhesive layer or a mastic layer may be formed on the outer peripheral surface of the cheap member in order to further increase the adhesion strength of the foam coating layer to the inner peripheral surface of the steel pipe.

Moreover, the metal sheet 2 is removed after the foamed covering layer 4 is formed. In order to further facilitate the removal of the metal thin plate and to prevent the cheap-shaped member and the metal thin plate from adhering during the above-mentioned JJO heating, it is possible to perform a mold release treatment on the contact surface of the thin plate with the cheap-shaped member. Possible NI type roasting treatment of thin metal sheets,
This can be done by coating the surface of the thin plate with a silicone resin, fluororesin, etc., or by adhering a sheet made of these resins to the surface of the thin plate.

FIG. 5 shows another example of the invention 12, a chive-shaped member 1
The inner peripheral surface is made of cross-linked polyethylene and has a thickness of approximately 0.3 to 3.
A protective layer 5 has been formed. Further, the metal thin plate 2 is made to slightly protrude from one end of the chive-shaped member l. According to this inner surface coating material, the protective layer 5 can form a coating layer having waterproof and moisture-proof properties. Further, there is an advantage that the work of removing the thin metal plate 2 after forming the foamed coating layer can be easily carried out by grasping the protrusion of the thin metal plate 2 from one end of the chive-shaped member 1. Note that, if desired, the thin metal plate can also be made to protrude slightly from both ends of the entire chive-shaped member.

The present invention is constructed as described above, and the thin metal plate is curved and housed along the inner wall surface of the heat-foamable cheap member so as to have rebound elasticity. It has the feature that a foamed coating layer can be formed on the inner circumferential surface of the article by a simple method of doing so.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 90 parts by weight of polyethylene pellets (manufactured by Gakuyu Kagaku Co., Ltd., trade name Sumirikisen G-801), 10 parts by weight of powdered polyethylene (manufactured by Steel Chemical Co., Ltd., trade name Frowsen UF-20), and decomposition temperature 154 to 159°C. Foaming agent 414-oxybisbenzenesulfonylhydrazi)'' (manufactured by Hydraulic Chemical Co., Ltd., trade name Cervon FE-9) A sheet-like material of size 111 was obtained, and both ends of this sheet-like material were overlapped and heat-sealed to give an outer diameter of 951fflff and a length of l.
A heat-foamable chive-shaped member of m is obtained.

Next, along the inner wall surface of this cheap member, one side was coated with silicone resin to form a mold release treatment I and a thickness of 0.1 m.
, a stainless steel plate with a length of 1" and a width of 31 m is stored in a curved manner.1.
Therefore, an inner surface coating material having the same structure as shown in Fig. @1 and Fig. @2 was obtained.

This inner coating material was coated with a 10OA steel pipe with a length of 1m (including 1100mm).
Insert into N) and heat using a hand gas burner from the steel pipe outer circumference side and the stainless steel plate side.

By this heating, the foaming agent decomposed and foamed, and the tube-like member expanded, and was pressed by the repulsive force of the stainless steel plate, forming a foamed coating layer that tightly adhered to the inner circumferential surface of the steel pipe.

The thickness of the foamed coating layer is approximately 2.5M, and the foaming ratio is 2 to 3.
It was double that.

Example 2 ・Organosilane-modified polyethylene pellets (manufactured by Mitsubishi Yuka Co., Ltd., trade name Linkron LF710) were melt-extruded [-1 thickness] to obtain a 51M sheet, and both ends of this sheet were heat-sealed to 1- A VCB tube with an outer diameter of 96C1N and a length of 1m was used, and the VCB tube was immersed in warm water at 80°C for 2 hours to crosslink (gel fraction: 50cm) to the extent that the reaction was not completed.

The outer circumferential surface of this crosslinked polyethylene tube was melted at a temperature of 105°C with a sheet-like material having a thickness of lff containing the foaming agent used in KIHieE Example 1. A tube-shaped member having an outer diameter of 97 cm and a length of 1 mm is obtained, having a protective layer made of polyethylene.

Next, along the inner wall surface of this thread-like member,
．． 1ff111, length 1.052j1. Curved storage of stainless steel plate for width 31 1. Therefore, an inner surface coating material having the same structure as shown in FIG. 5 was obtained.

This inner surface coating material was used to coat the inner surface of a steel pipe in the same manner as in Example 1.

In the case of this Example as well, the adhesion between the foamed coating layer and the steel pipe was strong, and the foaming state was also uniform. Note that the protective layer made of cross-linked polyethylene is insufficiently cross-linked, so its tensile strength is not very high, and the tension due to the rebound elastic force of the stainless steel plate is insufficient.
There was no interference with the pressing of the tab-shaped member.

In this way 1. The coating layer formed with this had both waterproof and moisture-proof properties due to the protective layer of cross-linked polyethylene. In addition, the crosslinking reaction of the protective layer further proceeded due to moisture in the air (12), and the gel fraction became 85%.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of the inner coating material of a chive-shaped member according to the present invention, FIG. 2 is a cross-sectional view taken along line A-B in FIG. 1 and viewed from the arrow direction, FIG. Figure 4 shows an example of how the inner coating material is used, and Figure 3 shows the state in which it is inserted into a steel pipe.
FIG. 4 is a side view showing the state after heating, and FIG. 5 is a sectional view showing another example of the present invention. 1...Cheve-shaped member 2...Metal thin plate 3...Steel pipe Patent applicant Representative Nitto Electric Industry Co., Ltd. Upper part 3 Figure 1 Figure 2 Figure 5

Claims (1)

[Claims] A cheep-shaped member that can be foamed by heating, and an inner surface covering material for the cheep-shaped article that is formed from a thin metal plate that is curved along the inner wall surface of the cheep-shaped member so as to have rebound elasticity.