JP2000314497A - Resin-coated steel pipe, and adhesive composition for the resin-coated steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a foaming layer to be provided, capable of sound insulating performance superior in a resin coated steel pipe and its adhesive, and manufacture them in existing steel pipe manufacturing equipment by coating the pipe with a resin via the adhesive composed of a saturated copolymer polyester resin, conjugate diene polymer, or its hydrogenated substance. SOLUTION: A resin coated steel pipe is provided by coating it with a resin, such as PVC via an adhesive composed of a saturated copolymer polyester resin of a weight average molecular weight of not less than 8,000 and not more than 100,000, conjugate diene polymer, or its hydrogenated substance. This resin coated steel pipe is superior in adhesion between a PVC coated layer and the steel pipe, and sound insulating performance so as to be widely used for a drain pipe, a hot water feed pipe, etc. The adhesive is preferably melted and mixed at the softening temperature of the saturated copolymer polyester resin or the conjugate diene polymer or higher, and an ordinary thermoplastic resin mixer can be used therefor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated steel pipe and an adhesive composition for the steel pipe, wherein a resin, particularly polyvinyl chloride (hereinafter, referred to as PVC) is provided on an inner surface or an outer surface of the steel tube.
The present invention relates to a steel pipe coated with a resin pipe, and a resin-coated steel pipe for reducing vibration and noise generated when a liquid flows through the pipe, and a resin-coated steel pipe for use in the production of the steel pipe. The present invention relates to an adhesive composition. The resin-coated steel pipe of the present invention, particularly a PVC-coated steel pipe or a galvanized steel pipe, can be widely used as a drain pipe, a water pipe, a hot water supply pipe, and a gas pipe in a corrosive environment such as a chemical or chemical factory. It is.

[0002]

2. Description of the Related Art The magnitude of drainage and water supply noise in buildings requiring quietness such as recent public housing, condominiums, hotels, and public facilities has become an important problem in today's emphasis on private. In addition, lighter pipes are required for these buildings due to their higher floors. Conventionally, cast iron pipes have been used as steel pipes with sound insulation performance. However, cast iron pipes are used as steel pipes with sound insulation properties because flake graphite is uniformly dispersed in a metal matrix (pearlite). However, the strength of cast iron pipe is not satisfactory because the graphite layer is dispersed, and in order to maintain strength, it has to be thicker than other steel pipes. Increase significantly. Further, Japanese Patent Publication No. 56-25375 discloses that a resin tube is provided inside a metal tube and on the inner surface of the metal tube so that the distance between the resin tubes is set to 0.
An adhesive layer which is inserted so as to have a thickness of 2 to 2 mm and which foams when heated is provided on the outer surface of the resin tube or the inner surface of the metal tube. A method of providing a foam layer in the middle of a resin tube has been proposed. However, this method has a drawback that unevenness in the thickness of the foamed layer occurs in the synthetic resin lining tube, and irregularities easily appear on the inner surface. The foamed layer is generally foamed by a reaction between an isocyanate compound and water, but is extremely toxic and has a serious problem in the environment of a production line. JP-A-63-20622 describes a method in which a rigid PVC pipe having a foamed PVC layer on the outer periphery is inserted into a metal pipe and lined with a hot melt adhesive. However, this method has a disadvantage that a method of applying a hot-melt adhesive to the outer surface of a PVC pipe, which is a general method of manufacturing a resin lining pipe on the inner face, cannot be taken. Because there is a foam layer on the outer periphery, there is a risk that the foam layer is broken when the hot melt adhesive is applied by an extruder, and when a solvent type adhesive is used, the adhesive layer cannot penetrate into the foam layer and penetrate. Therefore, there is a problem that the adhesive strength is reduced. In addition, the PVC pipe is heated and expanded to form an adhesive lining. However, there is a drawback that the foam layer reduces the pressure and a sufficient adhesive pressure cannot be obtained, resulting in a decrease in strength. There is also a problem that the flow rate becomes smaller when compared with the same diameter.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have developed a resin-coated steel pipe which has excellent sound insulation performance without providing a foam layer and which can be manufactured with existing coated steel pipe manufacturing equipment, and an adhesive for manufacturing the steel pipe. We did research to find out.

[0004]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have conducted intensive studies and found that a steel pipe and a resin pipe coated on the inner or outer surface of the steel pipe are bonded to each other with sound insulation performance having a large loss coefficient. It has been found that the above-mentioned problems can be solved by bonding with an agent, particularly a hot melt adhesive comprising a saturated copolymerized polyester resin and a conjugated diene polymer, and completed the present invention. That is, the present invention provides a resin-coated steel pipe, a saturated copolymerized polyester resin, and a conjugated diene resin, wherein the resin is coated via an adhesive comprising a saturated copolymerized polyester resin and a conjugated diene polymer or a hydrogenated product thereof. The present invention relates to an adhesive composition for a resin-coated steel pipe, which is a hot melt adhesive comprising a polymer or a hydrogenated product thereof.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Polyester Resin The polyester resin used in the present invention is a saturated copolymerized polyester resin having a weight average molecular weight (GPC, in terms of polystyrene) of 8,000 to 100,000. Polyester resins are preferred. When the weight average molecular weight is less than 8,000, the cohesive strength is lacking, and the adhesive strength, particularly, the adhesive strength at high temperatures is reduced, and the softening temperature is lowered, and the coated pipes may adhere to each other. is there. On the other hand, when the weight average molecular weight is more than 100,000, the melt viscosity at the time of coating becomes high, which may cause problems such as inability to coat or a significant reduction in production rate. More preferred saturated copolyester resin has a weight average molecular weight of 10,000 or more and 8 or more.
It is less than 000. Examples of the copolymerization component (monomer) constituting the polyester resin of the present invention include, but are not limited to, the following components.
As the acid component, terephthalic acid, isophthalic acid, phthalic anhydride, α-naphthalenedicarboxylic acid, β-naphthalenedicarboxylic acid and aromatic dibasic acids such as ester-forming products thereof, succinic acid, glutaric acid, adipic acid, Aliphatic dibasic acids such as pimelic acid, suberic acid, azelaic acid, sebacic acid, undecylenic acid, dodecane diacid and their ester-formers, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride And alicyclic dibasic acids. Of these compounds, terephthalic acid and its ester-form are preferred in terms of adhesive strength. The content of terephthalic acid is preferably 30 mol% or more based on the total acid components. When the terephthalic acid component is less than 30 mol%, the cohesive strength and hardness of the resin are insufficient, and the adhesive strength and The threading strength may be low. Also, polycarboxylic acids such as trimellitic acid and pyromellitic acid can be used together within a range that does not impair gelation or adhesive strength during polyester synthesis. Can be used in a range.

The polyol components include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol,
5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methylpentanediol, 2,2,3-trimethylpentanediol, diethylene glycol, triethylene Aliphatic glycols such as glycol and dipropylene glycol; and alicyclic glycols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A. Also,
Polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can also be used in an amount of 5 mol% or less based on all polyol components. The polyol used for preparing the polyester resin of the present invention is not limited, but it is preferable to use ethylene glycol and / or 1,4-butanediol. More preferably, ethylene glycol and / or 1,4-butanediol is used in an amount of 30 mol% or more based on all alcohol components. When the ratio is out of this range, the obtained polyester resin may lack cohesion, have low adhesive strength, and may have insufficient heat resistance.
The polyester resin of the present invention preferably has crystallinity, and the crystallinity is indicated by a heat of fusion of 1 J / g or more, which is a main endothermic peak measured by a differential scanning calorimeter. When the heat of fusion is smaller than this, the resin lacks cohesive strength due to crystallinity and the adhesive strength may be reduced, and the melting point indicated by the heat of fusion peak temperature is preferably 50 to 200 ° C, more preferably Preferably 70 to 150
° C. If it is smaller than this range, the heat resistance of the resin is insufficient, or the crystallization of the polyester resin after coating is slow and a tacky feeling is left, which hinders handling in a later step. If it is larger than this range, the coating temperature or the bonding temperature is too high, and the resin base material is thermally degraded,
It causes adhesion failure. Such a copolyester resin is produced by a usual method. For example, there are a melt polymerization method in which raw materials and a catalyst are charged and heated at a temperature higher than the melting point of the product, a solid phase polymerization method in which polymerization is performed at a temperature lower than the melting point of the product, a solution polymerization method using a solvent, and the like. Although a melt polymerization method may be employed, a melt polymerization method is preferred from the viewpoint of obtaining a polyester having an appropriate polymerization degree for the purpose of the present invention and economical efficiency, and it is produced by a transesterification method or a direct esterification method. Such a polyester resin can be produced by a known method.

[0007] Conjugated diene polymer The conjugated diene polymer used in the present invention has a carbon number of 1 to 1.
6, butadiene polymers or copolymers which may have a substituent in one or both of 1, 2 bonds or 3, 4 bonds or an alkyl group, a phenyl group or a chlorine atom, and hydrogenated products thereof. Specifically, a polymer mainly composed of a conjugated diene such as butadiene, isoprene or chloroprene forming a 1,2- or 3,4-bonded polymer is exemplified. Preferred for the present invention is a block copolymer represented by (ABA) n or (AB) n. Here, A is a block made of a polymer of a vinyl monomer such as ethylene, propylene, styrene, α-methylstyrene, and styrene having a methyl group on a benzene ring, and B is a block containing conjugated diene such as butadiene, isoprene and chloroprene in 1,2. It is a block forming a bonded or 3,4 bonded polymer or a hydrogenated product thereof. Particularly preferred in the present invention are those in which the A block is a polymer of styrene and the B block is a polymer of 1,2 or 3,4 bonds of isoprene, which are compatible with the saturated copolyester. Excellent in terms of. In the present invention, a conjugated diene polymer having a melt flow index of 0.5 to 200 g / 10 min is preferable, and a melt flow index of 0.5 g / 1.
If the time is less than 0 minutes, the viscosity when used as an adhesive becomes high, which may cause difficulty in coating. If the melt flow index is 200 g / 10 minutes or more, the cohesive strength is reduced and the adhesive strength is insufficient. Sometimes. These conjugated diene polymers may be produced by a known method, and commercially available products can be used without any problem. For example, as a commercial product, a block copolymer of styrene and 3,4-polyisoprene (Hybler 5217)
Kuraray Co., Ltd.), block copolymer of styrene and isoprene (Quintac 3421 manufactured by Nippon Zeon Co., Ltd., Septon 2043 by Kuraray Co., Ltd.), block copolymer of styrene and butadiene (KRATOND-11)
22X Shell Japan Co., Ltd.).
The mixing ratio of the saturated copolymerized polyester resin and the conjugated diene polymer or a hydrogenated product thereof is as follows.
The amount of the diene polymer or its hydrogenated product is preferably 5 to 100 parts by weight with respect to 00 parts by weight, and if the amount is less than 5 parts by weight, the resulting adhesive may have poor adhesion durability. This can cause problems.

Additives The adhesive of the present invention may contain various resins, organic alkoxysilanes, inorganic fillers, various stabilizers, etc. for various purposes within a range that does not impair the performance of the present invention. It is possible. As the various resins, polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, polyurethane resins, epoxy resins, phenoxy resins, phenol resins, petroleum resins, rosin resins, terpene resins, and the like other than the present invention can be blended. Useful of these additives are polyethylene resins, organoalkoxysilanes, terpene resins. As the polyethylene resin, various polyethylene resins, for example, any of ordinary polyethylene resins obtained by radical polymerization of ethylene are used.Specifically, low-density polyethylene produced by a high-pressure method, medium-pressure method / low-pressure method The high-density polyethylene, linear low-density polyethylene, and the like to be produced are exemplified. Of these, low-density polyethylene and linear low-density polyethylene are particularly preferable. Further, as the polyethylene resin, it is also possible to use a copolymer of α-olefin such as propylene and styrene, or a copolymer of maleic anhydride, vinyl acetate, acrylic acid, acrylate ester, methacrylic acid, methacrylic ester and the like. it can. The preferable blending amount of the polyethylene resin is 5 parts by weight or more and 100 parts by weight or less based on 100 parts by weight of the polyester resin.
If the amount is less than 5 parts by weight, the effect of improving the adhesion durability is small, and
If it exceeds 00 parts by weight, the adhesive strength and the sound insulation performance tend to decrease.

As the organic alkoxysilane, those usually called silane coupling agents can be used. For example, γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxytriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl)
-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl-tri (β-methoxyethoxy) silane And the like. Of these, epoxy group-containing organic alkoxysilanes are preferred. The preferred compounding amount of the organic alkoxysilane is 0.1 to 5 parts by weight based on 100 parts by weight of the polyester resin. When the amount is less than 0.1 part by weight, there is no effect in improving the adhesive durability, particularly in the water resistance. On the other hand, when the amount exceeds 5 parts by weight, a problem may occur in the stability after mixing. As the terpene resin, known ones are widely used, but preferred ones for the adhesive of the present invention are aromatic modified terpene resins having good compatibility with the saturated copolymerized polyester resin and capable of improving the adhesive strength. is there. Examples of commercially available products include YS Resin TO105 (manufactured by Yasuhara Chemical Co., Ltd.). The amount of the terpene resin is preferably 50 parts by weight or less based on 100 parts by weight of the polyester resin. As the inorganic filler, powder such as calcium carbonate, zinc oxide, titanium oxide, talc, clay, and fumed silica having a particle size of 10 μm or less can be used, and the compounding amount thereof is based on 100 parts by weight of the polyester resin. It is preferably at most 30 parts by weight. As a stabilizer, an antioxidant such as hindered phenol can be added. These additives may further improve the characteristics of the present invention, and can be appropriately used depending on the application.

The adhesive of the present invention is preferably melt-mixed at a temperature equal to or higher than the softening temperature of the saturated copolymerized polyester resin or the conjugated diene polymer. It can be manufactured by using a conventional thermoplastic resin mixer represented by a melt kneader of a system or a kneader-type heat mixer. Subsequent to the kneading, it is possible to form a pellet by a granulation process or to apply the mixture directly onto the adherend. Among them, the most preferable apparatus is an extruder of a twin screw type, and the maximum temperature of the cylinder during processing is preferably higher than the softening temperature of the polyester resin by 10 ° C. or more and 100 ° C. or less. ○ Steel pipe Examples of the steel pipe used in the present invention include a carbon steel pipe, a galvanized steel pipe, a stainless steel pipe, and the like. If necessary, the steel pipe is subjected to a treatment such as polishing and degreasing, a chemical treatment such as a chromic acid treatment and a phosphate treatment, and then an adhesive is applied. ○ Resin for coating Examples of the resin for coating used in the present invention include thermoplastic resins such as PVC, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, nylon resin, polyethylene resin, and polypropylene resin. When used, both excellent adhesiveness and sound insulation can be achieved. Such a coating resin is heat-bonded integrally with a steel pipe after being formed into a tubular shape in advance, and is melt-extruded into a steel pipe coated with an adhesive, and the like.
The application form can be appropriately changed depending on the manufacturing method. ○ Coating method In applying the adhesive of the present invention, a method in which pellets granulated by the above-described production method are applied to the outer surface of a steel pipe or a resin pipe from a circular die by a melt extruder, and the pellets are melted. Create a film from a T-die with an extruder,
Examples thereof include a method of winding around a steel pipe or a resin pipe, and a method of pulverizing granulated pellets, turning them into a powder, and coating them by fluid immersion, electrostatic coating, or the like. The thickness of the adhesive after coating is
It is 30 μm to 1 mm, preferably 100 to 500 μm. ○ Bonding method As a method of bonding using the adhesive of the present invention, in the case of a steel pipe coated with an adhesive, insert the steel pipe coated with the adhesive into a preformed heat-shrinkable resin pipe. A method of heating and a method of melt-extrusion-coating a resin for tube forming on a steel tube coated with an adhesive may be used. When an adhesive is applied to a preformed resin tube, a method of inserting the resin tube into a steel tube and heating or heating / pressing may be used. When bonding by post-heating, the furnace temperature is 100 to 30
The resin tube and the steel tube can be bonded via the adhesive layer melted by the pressure of the contracting or expanding resin tube by passing the resin tube through a heating furnace at 0 ° C. for 5 to 60 minutes. Applications The resin-coated steel pipe of the present invention is widely used for steel pipes such as drainage pipes, water distribution pipes, and hot water supply pipes that mainly allow water to pass through.

[0011]

The reason why the resin-coated steel pipe obtained by using the adhesive comprising the adhesive composition of the present invention exhibits high sound insulation, adhesive strength and long-term durability, and expresses practical strength is clear. However, it is estimated as follows. Polyester resin adheres firmly to steel pipe and resin pipe. By using a crystalline polyester resin having a relatively high molecular weight, a high cohesive force of the resin is obtained, and a high adhesive strength can be imparted in spite of high sound insulation. It is considered that the addition of a 1,2-bond or 3,4-bond block copolymer of a conjugated diene improves the loss coefficient of the adhesive, absorbs sound and vibration, and exhibits sound insulation. By incorporating a conjugated diene 1,2 bond or 3,4 bond block copolymer, shrinkage due to crystallization of the polyester resin is suppressed, which contributes to relaxation of the internal stress of the adhesive layer, and the adhesive strength is reduced over time. Does not change.

[0012]

EXAMPLES Examples of the present invention will be described below together with comparative examples. Prior to the description of the examples and the like, methods for measuring and evaluating physical properties in the following description will be described. ○ Method for measuring physical properties Weight average molecular weight: Measured by GPC and expressed in terms of polystyrene. Melting point: The temperature of the main endothermic peak was determined as the melting point by a differential scanning calorimeter. Glass transition point: Using a differential scanning calorimeter, the temperature at the inflection point on the low temperature side of the stepwise change portion was taken as the glass transition point. Loss factor: Measurement temperature 25 ° C, 1 by cantilever resonance method
It was measured at a resonance peak near 70 Hz. Hard PVC (3 mmt) is applied to a cold-rolled steel plate with a width of 20 mm, a length of 100 mm and a thickness of 1 mm as a test piece with an adhesive (coating thickness 300μ).
What was previously bonded in m) was used. Bonding method: Extruding an adhesive pellet from a round die under a temperature condition shown in Table 1 by a single screw extruder at 100A.
After being applied to a PVC pipe, it is inserted into a steel pipe and
Heating was performed for 0 minutes to expand the PVC pipe to produce an inner PVC coated steel pipe. Extrusion temperature conditions: as shown in Table 1 below.

[0013]

[Table 1]

Flowing sound measurement: A steel pipe coated on the inner surface under the above conditions was cut into 1 m, and the well water (18 m3 / Hr) was cut at 9 m ³ / Hr.
° C) and the generated sound was measured with a sound level meter. Punching test: The bonded resin-coated steel pipe was cut into 25 mm-widths, and the strength at which the steel pipe portion was punched out at 23 ° C at a punching speed of 5 mm / min was measured. The resin-coated steel tube measured was used initially (immediately after bonding) and left at 80 ° C. for 10 days.

Example 1 Synthesis of polyester resin In a four-necked flask equipped with a stirrer, a nitrogen inlet tube, a distilling tube, and a thermometer, 0.40 mol of dimethyl terephthalate, 1,4-
2.00 mol of butanediol and tetra-n- as catalyst
After charging 0.2 × 10 −2 mol of butyl titanate, the temperature was raised while introducing nitrogen, methanol was distilled at 130 to 200 ° C., and then 0.30 mol of isophthalic acid and 0.30 mol of adipic acid were added. Then, after distilling water at 200 to 240 ° C., continuously reducing the pressure gradually,
The reaction was continued under reduced pressure of 1 mmHg for 3 hours. The obtained polyester resin had a melting point of 110 ° C. and a heat of crystal fusion of 15 J /
g, weight average molecular weight 18,000. The monomer composition by NMR analysis was as follows: terephthalic acid / isophthalic acid / adipic acid / 1,4-butanediol = 40/30 in molar ratio.
/ 30/100. This is designated as polyester resin A. Preparation of adhesive 100 parts by weight of polyester resin A and styrene
3,4-Polyisoprene block copolymer Hybler VS
-3 (melt flow rate 14 g / 10 min, manufactured by Kuraray Co., Ltd., hereinafter referred to as conjugated diene block resin A)
30 parts by weight and 1 part by weight of γ-glycidoxypropyltrimethoxysilane (hereinafter referred to as organic alkoxysilane A) were mixed by a twin-screw extruder, and pelletized by a granulator. -Performance evaluation of coated steel pipe Using this pellet, a diameter of 100
A inner surface PVC coated steel pipe of A was prepared, and a steel pipe punching strength and a running water sound measurement test were performed.例 Examples 2 to 5 In the same manner as in Example 1, saturated copolymerized polyester resin B, hydrogenated styrene and isoprene block copolymer Septon 2043 (melt flow rate 10 g / 10 min, manufactured by Kuraray Co., Ltd. Diene block resin B), polyethylene-α-olefin copolymer resin Tuffmer P0180 (melt flow rate 1.4 g / 10 min, manufactured by Mitsui Chemicals, Inc .; hereinafter, this is referred to as polyethylene resin A) Using silane A,
YS resin TO1 which is an aromatic modified terpene resin
An adhesive composition was prepared by blending at a ratio shown in Table 2 using 05 (manufactured by Yasuhara Chemical Co., Ltd., hereinafter referred to as terpene resin A), and pellets were prepared to produce an inner surface PVC coated steel pipe. Table 2 shows the results of the running water noise measurement and the steel pipe punching test.

Comparative Examples 1-3 The raw materials used in Examples 1-5 and Evaflex EV-220 (melt flow rate 250 g / 10 min, manufactured by Mitsui Chemicals, Inc.) or ethylene-vinyl acetate resin An adhesive and its pellets were prepared using Acryft WH501 (a melt flow rate of 70 g / 10 minutes, manufactured by Mitsui Chemicals, Inc.), which is a methyl methacrylate resin. Furthermore, a resin-coated steel pipe was manufactured and its performance was evaluated. Table 3 shows the results.比較 Comparative Example 4 Table 3 also shows the measurement results of running water noise of cast iron pipes which are said to be excellent in sound insulation.

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

The resin-coated steel pipe of the present invention, in particular, the PVC-coated steel pipe has excellent adhesion and sound insulation between the PVC coating layer and the steel pipe, so that it can be widely used for drainage pipes, water distribution pipes, hot water supply pipes and the like. In addition, the adhesive composition is excellent in sound insulation when a fluid flows inside the coated steel pipe, and because it is a hot-melt adhesive having no volatile components, it is excellent in safety with little danger of flaming and odor.
This has an excellent effect of having an appropriate melt coatability.

Claims (2)

[Claims] 1. A resin-coated steel pipe coated with a resin via an adhesive comprising a saturated copolymerized polyester resin and a conjugated diene polymer or a hydrogenated product thereof. 2. An adhesive composition for a resin-coated steel pipe, which is a hot melt adhesive comprising a saturated copolymerized polyester resin and a conjugated diene polymer or a hydrogenated product thereof.