JPH06117581A - Method of manufacturing metal pipe lined with resin - Google Patents

Abstract

PURPOSE:To bond a resin pipe inserted in a metal pipe and press-fitted therein by reducing the diameter of the metal pipe without peel-off by making the resin pipe from specific amorphous resin, and by heat-treating the resin pipe at a predetermined temperature before the diameter of the metal pipe is reduced. CONSTITUTION:A resin lined metal pipe adapted to be used for a pipe line for hot water, steam or the like, is manufactured in such a way that at least one of the outer peripheral surface of the resin pipe and the inner peripheral surface of the metal pipe is coated with an adhesive, and then the resin pipe is inserted in the metal pipe before the diameter of the metal pipe is reduced so as to press-fit the resin pipe in the metal pipe. In such a manufacturing process, the resin pipe is formed from amorphous resin containing 10 to 50wt.% of inorganic filler. Further, during or after molding of the resin pipe but before reducing of the diameter of the metal pipe, the resin pipe is heat-treated at a heat-treatment temperature TA deg.C which satisfies Tg-5deg.C<=Ta<=Tg+10 deg.C where Tg is the glass transition temperature of the amorphous resin from which the resin pipe is formed. Thereby it is possible to enhance the peel-off resistance and the clack-resistance of the resin pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inner surface resin lined metal pipe used for water supply, hot water supply, steam supply and the like.

[0002]

2. Description of the Related Art Conventionally, an inner resin lined metal pipe has been widely used as a pipe for supplying water, supplying hot water, steam, and the like. If the resin forming the inner surface resin lining layer of the inner surface resin lining metal tube is made of a crystalline resin, the resin contracts during crystallization and cracks are likely to occur in the inner surface resin lining layer. For this reason, amorphous resins such as polyether sulfone, polysulfone, heat-resistant polyvinyl chloride, and polyvinyl chloride have no defects such as the above crystalline resins, and have excellent corrosion resistance and low water permeability. , Inner surface resin lining is used as a resin for the inner surface resin lining layer of metal tubes.

As a method of lining a metal tube, for example, as described in JP-A-59-59418, a synthetic resin tube made of an amorphous resin is inserted into a metal tube through an adhesive layer and then heated. Has proposed a method for expanding the diameter of a synthetic resin pipe.

[0004]

However, in the inner surface resin-lined metal pipe obtained by the conventional method as described above, the synthetic resin pipe has a larger coefficient of thermal expansion than that of the metal pipe.
In addition, since the resin pipe is lined with molding strain remaining during molding, when used as a pipe in which hot water repeatedly flows, the resin pipe and the metal pipe repeat different thermal expansion and contraction, respectively. As a result, there is a problem that the inner surface resin lining layer is easily peeled off from the inner surface of the metal pipe, and is particularly fragile at the pipe end portion.

The present invention solves the above-mentioned conventional problems, and the inner resin lining metal is less likely to peel off from the inner surface of the metal pipe even when used as a pipe in which hot water repeatedly flows. It was made for the purpose of manufacturing a tube.

[0006]

According to the present invention, an adhesive is applied to at least one of the outer peripheral surface of a resin pipe and the inner peripheral surface of a metal pipe, the resin pipe is inserted into the metal pipe, and then the diameter of the metal pipe is reduced. In the method for producing an inner resin lining pipe, which is pressure-bonded to a resin pipe and bonded, a resin pipe is molded using an amorphous resin containing 10 to 50% by weight of an inorganic filler, and a metal is used during or after the molding. Before reducing the diameter of the pipe, the following formula (1) Tg-5 ° C ≤ T _A ≤ Tg + 10 ° C formula (1) [Tg is the glass transition temperature (° C) of the amorphous resin forming the resin pipe. Indicates. ] The heat treatment temperature T _A (° C.) that satisfies

In the present invention, as the metal tube, iron,
Examples of the tube include steel, stainless steel, aluminum, copper, zinc and the like, which are generally called metals. The inner surface of the metal tube should be used in a state suitable for adhesion to the resin running layer by performing an oxide film removal treatment such as rust with sandblast, hydrochloric acid, sulfuric acid, nitric acid, etc., and a degreasing treatment with alkali etc. preferable. Also, a known adhesion promoter such as a primer may be applied.

In the present invention, the adhesive is usually
A rubber type solvent type adhesive is used, but a hot melt type adhesive, a reaction type adhesive or the like can also be used. .

In the present invention, 10 to 50 inorganic fillers are used.
A resin tube is molded by using an amorphous resin containing wt%.
In the present invention, examples of the amorphous resin (hereinafter referred to as resin) include polyether sulfone (Tg225).
℃), polysulfone (Tg190 ℃), polyarylate (Tg150 ℃), polychlorinated vinyl chloride (Tg105
C.), polyvinyl chloride (Tg 85.degree. C.) and the like are used.
The resins as described above are excellent in water resistance, chemical resistance, and heat resistance, and by lining the inner surface of the metal pipe, it is possible to obtain an inner resin lining metal excellent in water resistance, chemical resistance, and heat resistance. .

In the present invention, the inorganic filler contained in the resin is preferably one which has excellent water resistance and chemical resistance and is stable even at high temperatures. Examples thereof include glass, carbon, ceramics and metal oxides. A powdery material such as fibrous material, granular material, flakes, etc. is used.

In addition to metal oxides, ceramics also include silicon nitride, titanium nitride, boron carbide and the like.
As the metal oxide, alumina, iron oxide, titanium oxide,
Examples thereof include zirconium oxide, chromium oxide, nickel oxide and potassium titanate.

Since the resin contains an inorganic filler,
It is possible to increase the strength of the resin lining layer formed on the inner surface of the metal pipe and prevent the occurrence of cracks due to the shrinkage of the resin.

The content of the inorganic filler in the resin containing the inorganic filler is 10 to 50% by weight, preferably 20 to 40.
It is in the range of% by weight. If the content is less than 10% by weight, the desired effect cannot be obtained, and conversely, if it exceeds 50% by weight, the strength of the resin lining layer decreases and cracks occur when the metal tube is reduced in diameter. May occur, and excellent physical properties as a resin lining layer may not be obtained.

The resin pipe is manufactured by a known molding method. For example, it can be manufactured by melt-extruding a resin containing an inorganic filler into a tubular form from a die of an extruder and then taking it out with a take-up machine while cooling it.

In the present invention, the heat treatment of the resin pipe is performed.
The heat treatment may be performed during the molding of the resin pipe, or after the molding before insertion into the metal pipe, or after the insertion into the metal pipe and before the diameter reduction of the metal pipe. This heat treatment
This is done to reduce the dimensional change of the resin pipe as much as possible after the diameter reduction of the metal pipe.

The heat treatment temperature T _A (° C.) must be a temperature that satisfies the above formula (1). Heat treatment temperature T _A (℃)
However, if Tg is less than −5 ° C., residual strain during molding of the resin pipe cannot be removed, and conversely, if Tg is higher than 10 ° C., the resin pipe is deformed during heat treatment.

However, Tg is a dynamic viscoelasticity measurement (temperature rise 2 ° C./min) of the resin forming the resin tube, and the rate of change of the elastic modulus is 90% for the first time compared with the elastic modulus before 2 ° C. It shall be the following integer temperature (however, the measured temperature shall be rounded off).

[0018]

In the method for producing the inner surface resin-lined metal pipe of the present invention, the resin pipe is formed by using the amorphous resin containing 10 to 50% by weight of the inorganic filler, so that the linear expansion coefficient of the resin pipe is Is small, and the resin pipe is heat-treated at a heat treatment temperature T _A (° C.) satisfying the above formula (1) before or during the diameter reduction of the metal pipe at the time of molding or after the molding. Has been removed most of the time, and the stress at the adhesive interface after processing can be reduced, and when used as a pipe where hot water repeatedly flows, the adhesive surface, especially the inner surface of the metal pipe at the pipe end The resin lining layer does not peel off from the.

[0019]

EXAMPLES The present invention will be described below with reference to examples. Example 1 A. Molding and heat treatment of resin tube Tg225 containing 25% by weight of glass fiber powder
A polyethersulfone resin at ℃ was melt extruded from a mold and immediately water-cooled to form a resin tube having a thickness of 2 mm. Cut this resin pipe to a length of 5.5 m and set it at 230 ° C
And heat treated for 30 minutes to prepare a heat treated resin tube.

B. Production of Inner Surface Resin Lining Metal Tube A solvent-based adhesive composed of a rubber / epoxy component was applied to the outer surface of the heat-treated resin tube, dried at 80 ° C. for 10 minutes, and the solvent was volatilized to form an adhesive layer. Its outer diameter is 27.6
It was mm. The inner surface of a carbon steel pipe for piping having a nominal diameter of 25 A and a length of 5.5 m (inner diameter 29.6, thickness 3.2 mm) was treated by grid blasting, and then compressed air was blown to clean it. The same adhesive as above was applied to the inner surface of this steel pipe, dried under the same conditions as above, and the solvent was volatilized to form an adhesive layer.

In the steel pipe having an adhesive layer formed on its inner surface,
When the heat-treated resin tube having the adhesive layer formed on the outer surface was inserted at room temperature, the resin tube could be inserted extremely smoothly without any resistance.

Then, the diameter of the steel pipe was reduced by a diameter reducer until the inner diameter became 27.6 mm, and the inner surface of the steel pipe was adhered to the outer surface of the resin pipe on which the adhesive layer of the resin pipe was formed. afterwards,
This was heated at 80 ° C. for 30 minutes to crosslink the adhesive to manufacture an inner surface polyethersulfone resin lining steel pipe. The wall thickness accuracy of the polyethersulfone resin lining layer on the inner surface of this lining steel pipe is 2.0 mm ± 0.02.
mm, and no pinholes and bubbles were observed.

C. Performance Evaluation of Lining Steel Pipe The obtained lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation by the following test methods. The results are shown in Table 1. (1) Peeling test After making cuts in the resin lining layer at the end of the lining steel pipe to reach the steel pipe in a grid pattern at intervals of 3 mm using a knife, peeling the 1 mm square portion of the resin lining layer at the tip of the knife To determine whether or not peeling is possible. (2) Evaluation of accelerated cold / hot water A lining steel pipe was cut into a length of 1 m, immersed in hot water at 95 ° C for 5 minutes, and then immersed in cold water at 25 ° C for 5 minutes for 1000 cycles, and then the state of the lining steel pipe. Observe the appearance.

Comparative Example 1 A lining steel pipe was produced in the same manner as in Example 1 except that a resin fiber containing no glass fiber was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 2 A lining steel pipe was manufactured in the same manner as in Example 1 except that a resin pipe that was not heat-treated was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 3 A lining steel pipe was manufactured in the same manner as in Example 1 except that the resin pipe containing no carbon fiber and not heat-treated was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 4 A lining steel pipe was manufactured in the same manner as in Example 1 except that a resin pipe heat-treated at a heat treatment temperature of 150 ° C. was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 5 Using the resin pipe of Example 1 before heat treatment, heat treatment temperature 25
When heat treated at 0 ° C, the resin tube was deformed,
The lining steel pipe could not be manufactured.

Example 2 A. Molding and heat treatment of resin tube Tg19 containing 35% by weight of carbon fiber powder
A polysulfone resin at 0 ° C. was melt-extruded from a mold and then immediately water-cooled to form a resin tube having a thickness of 2 mm.
Cut this resin tube to a length of 5.5 m and make it 60 at 200 ° C.
Heat treatment was performed for a minute to produce a heat treated resin tube.

B. Production of Inner Surface Resin Lining Metal Tube A solvent-based adhesive composed of a rubber / epoxy component was applied to the outer surface of the heat-treated resin tube, dried at 80 ° C. for 10 minutes, and the solvent was volatilized to form an adhesive layer. Its outer diameter is 27.6
It was mm. The inner surface of a carbon steel pipe for piping having a nominal diameter of 25 A and a length of 5.5 m (inner diameter 29.6, thickness 3.2 mm) was treated by grid blasting, and then compressed air was blown to clean it. The same adhesive as above was applied to the inner surface of this steel pipe, dried under the same conditions as above, and the solvent was volatilized to form an adhesive layer.

Inside the steel pipe having an adhesive layer formed on its inner surface,
When the heat-treated resin tube having the adhesive layer formed on the outer surface was inserted at room temperature, the resin tube could be inserted extremely smoothly without any resistance.

Then, the diameter of the steel pipe was reduced by a diameter reducer until the inner diameter was 27.6 mm, and the inner surface of the steel pipe was formed into an adhesive layer. afterwards,
This was heated at 80 ° C. for 30 minutes to crosslink the adhesive to manufacture an inner polysulfone resin-lined steel pipe. The wall thickness accuracy of the polysulfone resin lining layer on the inner surface of this lining steel pipe was 2.0 mm ± 0.02 mm, and no pinholes and bubbles were observed. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 6 A lining steel pipe was manufactured in the same manner as in Example 6 except that a resin pipe containing no carbon fiber was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 7 A lining steel pipe was manufactured in the same manner as in Example 6 except that a resin pipe that was not heat-treated was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 8 A lining steel pipe was produced in the same manner as in Example 6 except that the resin pipe containing no carbon fiber and not heat-treated was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 9 A lining steel pipe was manufactured in the same manner as in Example 6 except that a resin pipe heat-treated at a heat treatment temperature of 150 ° C. was used. The lining steel pipe was subjected to a peeling test and a cold / hot water accelerated evaluation in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 10 Using the resin pipe of Example 6 before heat treatment, heat treatment temperature 24
When heat treated at 0 ° C, the resin tube was deformed,
The lining steel pipe could not be manufactured.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION The method for producing an inner surface resin lined metal pipe of the present invention is configured as described above, so that when it is used as a pipe through which hot water repeatedly flows,
Even if thermal expansion and thermal contraction are repeated, the resin lining layer does not peel off from the adhesive surface, particularly the inner surface of the metal tube at the tube end.

Claims (1)

[Claims] 1. An adhesive is applied to at least one of the outer peripheral surface of a resin pipe and the inner peripheral surface of a metal pipe, the resin pipe is inserted into the metal pipe, and then the diameter of the metal pipe is reduced and pressure-bonded to the resin pipe for adhesion. In the manufacturing method of the inner surface resin lining pipe,
Before using the amorphous resin containing the inorganic filler in an amount of 10 to 50% by weight and reducing the diameter of the metal tube during or after the molding, the following formula Tg-5 ° C ≤ T _A ≤ Tg + 10 ° C [ Tg represents the glass transition temperature (° C.) of the amorphous resin forming the resin tube. ] It heat-processes at the heat processing temperature T _A (° C.) satisfying the above condition.