JPH05169540A - Manufacture of metal pipe lined with heat-resistant pvc resin - Google Patents

Abstract

PURPOSE:To provide the manufacturing process of a highly heat-resistant vinyl chloride resin wherein it does not cause any hazard due to solvent vaporization and deteriorate environmental health conditions and it is free from any defects such as floating and swelling. CONSTITUTION:The subject heat-resistant polyvinyl chloride resin-lined metal pipe is manufactured by applying a hot melt solvent which consists mainly of crystalline polyester with a melting point temperature of 120 to 150 deg.C and a crystallization temperature of 80 deg.C or higher to lower than a melting point temperature to the peripheral surface of a thermal expansible, heat-resistant PVC resin pipe. Consequently, this pipe is almost free from hazards such as solvent vaporization and environmental health deterioration. In addition, it has no defects such as floating and swelling.

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 a heat-resistant vinyl chloride resin-lined metal tube using a heat-expandable heat-resistant vinyl chloride resin tube.

[0002]

2. Description of the Related Art An adhesive is applied in advance to the outer surface of a synthetic resin tube having a thermal expansion property in order to impart corrosion resistance to the inner surface of a metal tube such as a steel tube to form a laminated tube for lining. It is well known that a synthetic resin lining is formed by inserting the resin into a slab and heating it to expand and bond it. Conventionally, a solution type rubber adhesive or a hot melt adhesive has been used as an adhesive used in such a method.

[0003]

However, for heat-resistant synthetic resin pipes intended for hot water supply piping materials, only solution-type rubber adhesives are used because conventional hot-melt adhesives do not have heat resistance. I couldn't. Therefore, the solvent contained in the solution-type rubber-based adhesive inevitably requires a drying step, and there is a risk of explosion due to the filling of the solvent vapor, which is not preferable in the hygienic environment.

[0004]

According to the present invention, there is no fear of danger due to solvent vapor or deterioration of sanitary environment, and the floating
It is an object of the present invention to provide a method for producing a heat-resistant vinyl chloride resin-lined metal tube having no defects such as swelling and extremely excellent heat resistance.

The present invention is intended to achieve the above object, and the gist of the present invention is to insert a heat-expandable heat-resistant vinyl chloride resin tube into a metal tube and heat the metal tube to heat the metal tube inside the metal tube. In a method for producing a lining metal pipe in which a heat-resistant vinyl chloride pipe is expanded and lined, an adhesive layer applied to the outer peripheral surface of the heat-expandable heat-resistant vinyl chloride resin pipe contains a crystalline polyester resin as a main component and has a melting point of 120. ~
A method for producing a heat-resistant vinyl chloride resin-lined metal pipe, which is a hot-melt adhesive having a crystallization temperature of 150 ° C. and a melting point of 80 ° C. or more, and an adhesive applied to the outer peripheral surface of the heat-expandable heat-resistant vinyl chloride resin pipe. Has a melt viscosity of 15
Shear rate of 10 when measured with a Koka type flow tester (nozzle diameter 1 mm, nozzle length 10 mm) at 0 ° C.
The method for producing a heat-resistant vinyl chloride resin-lined metal tube is characterized in that it is 10,000 poise or more at sec ^-1 .

The adhesive of the present invention is required to have heat resistance because the lining pipe is practically used for hot water supply, and in order to satisfy this requirement, a crystalline polyester resin is contained as a main component. .. Further, for the purpose of improving adhesiveness, cohesive strength, water resistance and the like, a polyolefin resin and other additives are blended within a range not exceeding 120 parts by weight with respect to 100 parts by weight of the polyester resin. ..

The crystalline polyester resin, which is an essential component used in the present invention, has a melting point in the range of 120 ° C. to 150 ° C., and the crystallization temperature at the time of temperature decrease must be 80 ° C. or higher and the melting point or lower. Here, the melting point is a value measured by a differential scanning calorimeter, and is an endothermic peak when the temperature is increased to 200 ° C. at a scanning rate of 10 ° C./min, cooled to 0 ° C. at the same rate, and further increased to the same rate. The crystallization temperature means the temperature observed, and the crystallization temperature is the same as that of the melting point rate, and the temperature is from 200 ° C to 0 ° C.
It means the temperature observed as an exothermic peak when cooled to 0 ° C, and is usually the temperature below the melting point. When two or more peaks corresponding to the melting point and the crystallization temperature are observed, the one observed at the highest temperature may be in the above range.

The melting point of the crystalline polyester resin is 120
When the temperature is lower than ℃, the heat resistance of the adhesive is insufficient, and peeling easily occurs at high temperature use, resulting in impracticality. Further, when the melting point exceeds 150 ° C., it becomes necessary to set the resin temperature at the time of applying to the vinyl chloride resin pipe to be excessively high, which causes thermal deformation of the resin pipe and deterioration of the polyester resin due to thermal decomposition, oxidative decomposition and the like. It may be inconvenient. Furthermore, the crystallization temperature is 80 ℃
If it is lower than the above range, the phenomenon of "floating", which is peeled off due to the contraction stress of the heat-expandable heat-resistant vinyl chloride resin tube, easily occurs in the cooling process of the lining step, which is not preferable.

The crystalline polyester resin in the present invention means a thermoplastic saturated copolymerized polyester obtained by polycondensation of glycol and dicarboxylic acid, and its acid component is, for example, terephthalic acid, isophthalic acid, orthophthalic acid, Aromatic dibasic acids such as paraphenylenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, suberic acid, β-methyladipic acid, pimelic acid, 1,6-hexanedicarboxylic acid, Aliphatic dibasic acids such as azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, hexadecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid can be mentioned. As glycol components, ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, 3-methylpentadiol, 1,3-hexanediol, Glycols such as 1,6-hexanediol, hydrogenated bisphenol A, diethylene glycol, 1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol or their residue-forming derivatives or It can be obtained by appropriately selecting and copolymerizing a saturated bifunctional monomer such as an α, ω-oxy acid such as caprolactone or a residue-forming derivative thereof by a conventional method.

Further, for the purpose of improving physical properties such as adjustment of crystallinity, a trifunctional or higher functional acid component such as trimellitic acid or pyromellitic acid and / or a trifunctional or higher functional polyol component such as trimethylolpropane pentaerythritol is copolymerized in a trace amount. It may be something. Further, two or more kinds of polyesters may be blended so that the melting point and the crystallization temperature of the crystalline polyester resin are in the above ranges, or the same resin having a different degree of polymerization may be blended.

Next, as a component other than the above crystalline polyester resin, a polyolefin resin is generally suitable for improving low temperature characteristics and water resistance. The polyolefin resin is not particularly limited, but low density polyethylene or polyethylene resin obtained by copolymerizing propylene, maleic anhydride, vinyl acetate, acrylic acid, acrylic acid ester, methacrylic acid and the like is preferable.

As the polymer other than the polyolefin resin, for example, a thermoplastic resin such as an amorphous polyester resin, polystyrene resin or polyurethane resin may be blended according to the purpose, or an epoxy resin, It may be a mixture of thermosetting resins such as phenol resin and melamine resin. Further, other additives such as coupling agents such as silane coupling agents for the purpose of improving adhesion to metal pipes, talc, clay, fillers such as silica for improving cohesive force, and other known weather stabilizers, Antiaging agents, processing stabilizers and the like can be added within a range that does not impair the characteristics of the present invention.

Next, the manufacturing method of the present invention will be described.
First, as the heat-expandable heat-resistant vinyl chloride resin tube used in the present invention, a tube containing post-chlorinated vinyl chloride as a main component,
What was manufactured by extruding a mixture of polyvinyl chloride resin with a known heat resistance improver, if necessary, with stabilizers, fillers, lubricants, etc. preferable. Further, as the metal pipe to be lined, a carbon steel pipe for water supply, a galvanized steel pipe and the like are generally used, but the metal pipe is not limited to this.

On the outer peripheral surface of the expansive heat-resistant vinyl chloride pipe,
A laminated pipe for lining is formed by a melt coating method in which the above adhesive layer is melted by a crosshead die, a melt winding method in which the adhesive is extruded and wound in a strip shape, or a film winding method in which a film adhesive is wound around a vinyl chloride pipe. Constitute.

Next, the laminated tube for lining is inserted into a metal tube, and is expanded and adhered by sequentially heating from the outside of the metal tube from one end to the other end or from the center to both ends with a burner, hot air, or the like. In this case, the heating condition is preferably such that the surface of the metal tube is 130 ° C to 200 ° C. The reason for adopting such a heating method is to efficiently discharge the air existing in the gap between the vinyl chloride pipe and the metal pipe to the end portion, but in reality, uneven heating causes uneven expansion. For this reason, air is not completely discharged depending on the properties of the adhesive, and the phenomenon that bubbles remain between the metal pipe and the adhesive is likely to occur, leading to a decrease in the lining strength. This phenomenon tends to occur in a method in which the melt viscosity of the adhesive is low, and the adhesive in the present invention has an apparent melt viscosity measured by a Koka type flow tester (nozzle diameter 1 mm, nozzle length 10 mm) at 150 ° C. Is preferably 10,000 poise or more at a shear rate of 10 sec-1.

Next, in the cooling step of the lining tube which is expanded by heating and bonded as described above, there is a large difference in linear expansion coefficient between the heat resistant vinyl chloride tube and the metal tube in general, and the adhesive layer is formed in the cooling process. Since a stress in the peeling direction is applied to the pipe, the phenomenon of so-called “floating” in which the heat-resistant vinyl chloride pipe peels from the metal pipe easily occurs. In the present invention, in order to prevent such an inconvenience, it is preferable to introduce a pressurizing medium in the lining step to cool the inside of the vinyl chloride pipe in a pressurized state. Specifically, the inside of the vinyl chloride pipe may be pressure-sealed before heating, and the diameter may be increased by heating to expand the lining, or the vinyl chloride pipe may be heated and expanded, and then pressurized air is enclosed. After that, it may be cooled, or at the same time when the vinyl chloride pipe is heated and expanded in diameter, a pressurized air heated at the same time may be enclosed and lined. The pressure of the pressurizing medium is not particularly limited as long as the vinyl chloride tube can be sufficiently pressure-bonded to the metal wall surface, but is usually 0.5 kg / cm ² to 4.0 kg /
A range of cm ² is preferred.

[0017]

【Example】

Example 1 Commercially available polyester-based adhesive Polyester SP having physical properties shown in Table 1 using a crosshead die on the outer surface of a heat-expandable heat-resistant vinyl chloride resin tube (Hishipipe HT-E20A manufactured by Mitsubishi Plastics Co., Ltd.) having a length of 6 m. -166 (Nippon Gosei Kagaku Kogyo Co., Ltd.) is extrusion coated, and this heat-resistant vinyl chloride resin pipe with adhesive is inserted into a carbon steel pipe for water pipes with an inner diameter of 20 mm and a length of 5.5 m, and after lining the inner surface When observed, there was no floating or swelling, and as shown in Table 1, a heat-resistant vinyl chloride resin-lined metal tube having a good appearance was obtained.

Comparative Example 1 Lining was carried out in the same manner as in Example 1 except that Aronmelt PES-112 (manufactured by Toagosei Kagaku Co., Ltd.) having the physical properties shown in Table 1 was used as the polyester hot melt adhesive. As shown in, the melting point of the adhesive was low, and thus it was slightly floating, and the adhesive strength at high temperatures was low.

Comparative Example 2 Hardec A-3410 (manufactured by Asahi Kasei Co., Ltd.) having physical properties shown in Table 1 as a polyester hot melt adhesive.
Lining was performed in the same manner as in Example 1 except that the heat-resistant vinyl chloride resin pipe was peeled off from the inner surface of the steel pipe due to the low crystallization temperature as shown in Table 1, and floating occurred.

Comparative Example 3 Lining was performed in the same manner as in Example 1 except that Aronmelt PES-126E (manufactured by Toagosei Kagaku Co., Ltd.) having the physical properties shown in Table 1 was used as the polyester hot melt adhesive. As shown in (1), bubbles were generated due to the low melt viscosity, and so-called swelling occurred.

Comparative Example 4 Polyester SP-160 (Nippon Gosei Kagaku Co., Ltd.) having the physical properties shown in Table 1 as a polyester hot melt adhesive was used.
When the lining was performed in the same manner as in Example 1 except that the heat-resistant vinyl chloride resin pipe in the steel pipe was partially foamed, the melting point was too high and the pipe was not foamed. It was impossible to line the street.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to obtain a heat-resistant vinyl chloride resin tube which is free from problems such as danger due to solvent vapor and deterioration of sanitary environment and has no defects such as floating and swelling.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location B32B 15/08 102 A 7148-4F C09J 167/02 JFT 8933-4J // B29K 27:06 B29L 9:00 4F 23:22 4F

Claims (2)

[Claims] 1. A method for producing a lining metal pipe, comprising inserting a heat-expandable heat-resistant vinyl chloride resin pipe into a metal pipe, heating the metal pipe, and expanding and lining the heat-resistant vinyl chloride pipe in the metal pipe. A hot-melt adhesive in which the adhesive layer applied to the outer peripheral surface of the heat-expandable heat-resistant vinyl chloride resin tube contains a crystalline polyester resin as a main component and has a melting point of 120 to 150 ° C. and a crystallization temperature of 80 ° C. or higher and a melting point or lower. A method for producing a heat-resistant vinyl chloride resin-lined metal pipe, which is characterized by being present. 2. A shear rate of 10 when measured by a Koka type flow tester (nozzle diameter 1 mm, nozzle length 10 mm) at a melt viscosity of an adhesive applied to the outer peripheral surface of a heat-expandable heat-resistant vinyl chloride resin tube at 150 ° C. ¹ in sec ^-1
The method for producing a heat-resistant vinyl chloride resin-lined metal tube according to claim 1, wherein the method is at least 10,000 poise.