JP3324880B2 - Multilayer pipe and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic multilayer pipe. More specifically, the present invention relates to a plastic multilayer suitable for use in equipment such as central heating by a hot water (hot water) circulation method, centralized floor heating, and other hot water or hot water supply, circulation, and discharge equipment. The present invention relates to a pipe, and the multilayer pipe of the present invention is excellent in workability and durability, and furthermore, gas such as oxygen does not enter the pipe through the pipe wall. When it is used by attaching it to various facilities such as a pump for handling hot water or hot water, corrosion of metal parts used in those facilities can be prevented.

[0002]

2. Description of the Related Art Metal pipes such as iron and copper have been mainly used as pipes for circulating hot water or hot water for floor heating or central heating. These metal pipes are often buried in concrete during construction or installed under the floor, and in most cases once installed, it is difficult to repair them thereafter. Moreover, these facilities are required to have long-term durability, for example, about 30 to 50 years. However, conventional metal pipes are relatively expensive, and are poor in workability because they require welding and the like, and are liable to cause water leakage or the like at welded portions, and iron pipes are susceptible to corrosion.

In view of the above, plastic pipes which are inexpensive and have less seams and do not cause leakage at welds have been used in recent years as hot water or hot water circulation pipes instead of metal pipes. For example, pipes made of polyolefin such as cross-linked polyethylene, polypropylene, and polybutene are used. However, when plastic pipes are used, although leakage at the welded parts of the pipes is reduced compared to metal pipes,
Unexpectedly, a new problem has arisen that corrosion of metal parts in devices such as heat exchangers and pumps used in equipment such as floor heating increases. And
In a subsequent study, the corrosion of this metal part was caused by oxygen gas and carbon dioxide gas in the atmosphere penetrating into the pipe through the pipe wall of the plastic pipe, and these gases were dissolved in warm water or hot water flowing through the pipe, It has been found that this dissolved gas results from corrosion of the metal parts.

Therefore, in order to prevent gas such as oxygen gas in the atmosphere from permeating through the pipe wall and to impart gas barrier properties to the plastic pipe, saponified aluminum, ethylene-vinyl acetate copolymer, Gas barrier materials such as polyvinyl alcohol, polyvinylidene chloride, and polyacrylonitrile, especially a layer made of oxygen-barrier material can be provided on the surface of plastic pipes, or gas-barrier materials can be mixed into the plastics that make up the pipes. It has been proposed to.

[0005] However, when the aluminum layer is provided outside the plastic pipe, there is a drawback that when bending is performed at the time of construction, pinholes are generated and water leakage easily occurs. Further, at present, plastics such as polyvinyl alcohol, polyvinylidene chloride and polyacrylonitrile are not practically used due to poor molding workability, and are inferior in workability to the outside of plastic pipes.

Further, the saponified ethylene-vinyl acetate copolymer is superior in molding workability as compared with polyvinyl alcohol, polyvinylidene chloride, and the like. Therefore, it has already been proposed to provide the saponified product in the outermost layer of a plastic pipe ( JP-A-61-83035, JP-A-61-140
691), and the pipe obtained thereby has a saponified ethylene-vinyl acetate copolymer having a high elastic modulus in the outermost layer, so that it is difficult to bend when attached to a floor or the like, and is inferior in workability. . Further, in some cases, the diameter of the pipe is locally narrowed at the place where the bending is performed, so that hot water or hot water becomes difficult to flow, and cracks due to strains are liable to occur. If any of the above-mentioned conventional pipes is buried in concrete or the like and the above-described abnormality occurs, it cannot be easily replaced, which causes a major trouble.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pipe having excellent properties such as durability, corrosion resistance, flexibility, and heat resistance, and having excellent gas barrier properties without passing oxygen gas or other gases. Plastic pipes that can suppress corrosion in the metal parts of the equipment to which they are attached, are easy to mold and process, and do not crack at the parts even when the pipe is bent, and are excellent in workability, especially An object of the present invention is to provide a plastic pipe suitable for use in hot water or hot water circulation, supply and discharge routes.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies and have found that water-crosslinked polyolefin,
An inner-layer pipe was manufactured from radiation-crosslinked polyolefin, peroxide-crosslinked polyolefin, polybutene, and the like, and the outside thereof was extruded and coated with a saponified ethylene-vinyl acetate copolymer through an adhesive layer to manufacture a multi-layer pipe. Then, the oxygen barrier properties and durability of the obtained multilayer pipe, the occurrence of abnormalities such as cracks during bending of the pipe, and changes in the cross-sectional area of the pipe were examined. As a result, a multi-layer pipe provided with an outer layer made of saponified ethylene-vinyl acetate copolymer has a larger force when bending the pipe than a pipe without an outer layer made of saponified ethylene-vinyl acetate copolymer. If it is necessary, and if the curvature is reduced at the time of bending (for example, the radius of curvature is reduced to 100 mm or less), the pipe may be bent, the cross-sectional area of the pipe may be reduced,
It was found that wrinkles and streaks occurred in the outer layer, and the workability was poor.

It has been found that the above troubles are caused by the high elastic modulus of the saponified ethylene-vinyl acetate copolymer constituting the outer layer. Ethylene-vinyl acetate copolymer saponified ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-acrylic acid copolymer, polyamide-based elastomer, polyester-based elastomer or polyether-based elastomer A polymer composition is prepared by blending at a ratio of about 50% by weight, and each polymer composition is used as a material for an outer layer and extruded onto an inner layer pipe such as a water-crosslinked polyolefin in the same manner as described above. Coated to produce multilayer pipe. A bending test was performed on each of the resulting multilayer pipes. As a result, an outer layer was formed from a polymer composition in which an ethylene-vinyl acetate copolymer was blended with a saponified ethylene-vinyl acetate copolymer. It was found that only the pipe had a small stress at the time of bending and was excellent in corner bending workability, did not cause whitening at the bent portion of the pipe, and could suppress a decrease in gas barrier properties.

Therefore, the above-mentioned multi-layer pipe having an outer layer made of a polymer composition obtained by blending an ethylene-vinyl acetate copolymer with a saponified ethylene-vinyl acetate copolymer has a thickness of 95%.
When the gas barrier property was examined by using the pipe repeatedly in almost the same situation as the pipe is actually used in a hot water circulator, etc. through hot water at ℃, the gas barrier property was found to be low after a certain period of use. Had dropped significantly. And, as a result of further study, in search of a method for preventing such a decrease in gas barrier properties, a polymer composition obtained by blending an ethylene-vinyl acetate copolymer with a saponified ethylene-vinyl acetate copolymer was used as an outer layer. When the above-mentioned multilayer pipe was irradiated with radiation from the outer layer side, it was found that there was no decrease in gas barrier properties even after passing hot water for a long time.

However, the above-described method of irradiating the radiation increases the production cost and the high bending elastic modulus of the above-mentioned saponified ethylene-vinyl acetate copolymer during the construction. The problem has not been fully resolved. Accordingly, as a result of intensive studies to solve these problems, (A) saponified ethylene-vinyl alcohol copolymer (a1), a boronic acid group, a borinic acid group, and a boronic acid group in the presence of water; Outer layer or outer layer made of resin composition containing polyolefin (a2) having at least one functional group selected from boron-containing groups that can be converted to acid groups, (B) Inner layer or inner layer made of polybutene or crosslinked polyolefin Multi-layered pipe having a closer layer and (C) an adhesive layer bonding the layers, and (A) saponified ethylene-vinyl alcohol copolymer (a1), boronic acid group, borinic acid group, presence of water A polyolefin (a2) having at least one functional group selected from a boronic acid group and a boron-containing group that can be converted into a borinic acid group under heat and Layers than the outer layer or outer layers made of a resin composition containing a plastic resin (a3);
This is achieved by providing a multi-layer pipe having (B) an inner layer or a layer near the inner layer made of polybutene or a crosslinked polyolefin, and (C) an adhesive layer bonding the layers.

In the multilayer pipe of the present invention, the saponified ethylene-vinyl alcohol copolymer (a1) used for the outer layer or the layer (A) near the outer layer (both are collectively referred to as “outer layer (A)”). (Hereinafter abbreviated as EVOH) is a saponified ethylene-vinyl ester copolymer having an ethylene content of preferably 20 to 80 mol%, more preferably 22 to 70 mol%, and saponification of a vinyl ester component. The degree is preferably 80% or more, more preferably 85% or more. If the ethylene content is less than 20 mol%, melt moldability is poor, and gas barrier properties and thermal stability are poor. As a vinyl ester, vinyl acetate is mentioned as a typical example, but other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used. When EVOH contains 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymer component, the consistency of the melt viscosity with the base resin at the time of coextrusion is improved, and a homogeneous coextruded multilayer film is obtained. Not only can be manufactured, but also the dispersibility when EVOH is blended and used is improved, which is effective in improving moldability and the like. Here, as the vinylsilane-based compound, for example,
Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, γ
-Methacryloxypropylmethoxysilane. Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other comonomers such as propylene, butylene, unsaturated carboxylic acid or its ester ((meth) acrylic acid, (meth) acrylate methyl, ethyl) and the like, as long as the object of the present invention is not hindered. ｝, Vinylpyrrolidone (such as N-vinylpyrrolidone) can also be blended. Further, the preferred melt index (MI) of EVOH used in the present invention is a value measured at 190 ° C. under a load of 2160 g; those having a melting point of around 190 ° C. or exceeding 190 ° C. under a load of 2160 g under a plurality of temperatures higher than the melting point. Measure,
In a semilogarithmic graph, the reciprocal of the absolute temperature is plotted on the horizontal axis, and the melt index (log) is plotted on the vertical axis, and the value｝ extrapolated to 190 ° C. is 0.1 to 50 g / 10 min. , Optimally 0.5 to 20 g / 10 min. It is. In the present invention, it may be more preferable to use one or more EVOHs having different ethylene contents and / or saponification degrees in a blended state.

[0013] Further, other additives (plasticizer, heat stabilizer, ultraviolet absorber, antioxidant, coloring agent, filler, other resin, etc.) may be used in EVOH within a range that does not impair the object of the present invention. Is free. In particular, as a countermeasure against gel generation, hydrotalcite-based compounds, hindered phenol-based, hindered amine-based heat stabilizers, metal salts of higher fatty acid carboxylic acids (for example, calcium stearate, calcium magnesium stearate, etc.)
It is preferable to add 0.01 to 1% by weight of one or more of the above.

In the present invention, a boronic acid group, a borinic acid group,
The polyolefin (a2) having at least one functional group selected from a boronic acid group and a boron-containing group that can be converted to a borinic acid group in the presence of water includes a boronic acid group,
Bolinic acid group, boronic acid group in the presence of water, at least one functional group selected from the group consisting of boron-containing groups that can be converted to a borinic acid group is bonded to the main chain, side chain or terminal by a boron-carbon bond. It is a polyolefin. this house,
A polyolefin having the functional group bonded to a side chain or a terminal is preferable, and a polyolefin having a terminal bonded is most suitable. Here, the term "end" means one end or both ends. Further, the carbon of the boron-carbon bond is derived from a base polymer of a polyolefin described later, or derived from a boron compound reacted with the base polymer.
Preferable examples of the boron-carbon bond include a bond between boron and an alkylene group in a main chain or a terminal or a side chain. In the present invention, since a polyolefin containing a boronic acid group is suitable, the following points will be described. In the present invention, the boronic acid group is represented by the following (I).

[0015]

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The boron-containing group which can be converted to a boronic acid group in the presence of water (hereinafter simply referred to as boron-containing group) is represented by the above formula (I) after hydrolysis in the presence of water. Any boron-containing group that can be converted to a boronic acid group,
Any one may be used, and as typical examples, a boronic ester group represented by the following general formula (II) and a boronic ester group represented by the following general formula (II)
The boronic acid anhydride group represented by I) and the boronic acid salt group represented by the following general formula (IV) are exemplified.

[0017]

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[0018]

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[0019]

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In the formula, X and Y represent a hydrogen atom, an aliphatic hydrocarbon group (such as a linear or branched alkyl group or alkenyl group having 1 to 20 carbon atoms) and an alicyclic hydrocarbon group (cyclo Alkyl group, cycloalkenyl group, etc.), aromatic hydrocarbon group (phenyl group, biphenyl group, etc.)
X and Y may be the same or different. X and Y may be bonded. However, it is excluded when both X and Y are hydrogen atoms. R1, R2, and R3 represent the same hydrogen atom, aliphatic hydrocarbon group, alicyclic hydrocarbon group, and aromatic hydrocarbon group as those of X and Y, and R1, R2, R
3 may be the same or different. M represents an alkali metal or an alkaline earth metal. X, Y, R1, R2 and R3 may have other groups such as a carboxyl group and a halogen atom. ｝

Specific examples of the boronic ester groups represented by the general formulas (II) to (IV) include dimethyl boronate, diethyl boronate, dipropyl boronate, diisopropyl boronate, and boronate. Acid dibutyl ester group, boronic acid dihexyl ester group, boronic acid dicyclohexyl group, boronic acid ethylene glycol ester group, boronic acid propylene glycol ester group (boronic acid 1,2-propanediol ester group, boronic acid 1,3-propanediol ester Group),
Boronic acid ester groups such as boronic acid trimethylene glycol ester group, boronic acid neopentyl glycol ester group, boronic acid catechol ester group, boronic acid glycerin ester group, and boronic acid trimethylolethane ester group; boronic acid anhydride group; boronic acid And alkaline earth metal bases of boronic acid.

Among the above functional groups, a boronic ester group such as a boronic acid ethylene glycol ester group is particularly preferred from the viewpoint of compatibility with EVOH (d). The above-mentioned boron-containing group which can be converted into a boronic acid group in the presence of water is defined as a polyolefin in water or a liquid mixture of water and an organic solvent (toluene, xylene, acetone, etc.) in a reaction time of 10 minutes to 10 minutes. It means a group that can be converted into a boronic acid group or a borinic acid group when hydrolyzed at a reaction temperature of room temperature to 150 ° C. for 2 hours.

The content of the functional group is not particularly limited,
It is preferably 0.0001 to 1 meq / g (milli-equivalent / g), and particularly preferably 0.001 to 0.1 meq / g.
It is surprising that the compatibility, transparency and the like of the resin composition are remarkably improved by the presence of such a small amount of the functional group. Examples of the base polymer of the boronic acid-modified polyolefin (b) include olefin monomers represented by α-olefins such as ethylene, propylene, 1-butene, isobutene, 3-methylpentene, 1-hexene and 1-octene. Is raised.

The base polymer is used as a polymer composed of one, two or three or more of these monomers. Among these base polymers, especially ethylene-based polymer ｛ultra low density polyethylene, low density polyethylene,
Medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, metal salt of ethylene-acrylic acid copolymer (Na, K, Zn ionomer) ), Ethylene-propylene copolymers and the like, and propylene-based polymers.

The preferred melt index (MI) of the polyolefin (b) used in the present invention (210 ° C., 216
(Measured under a load of 0 g) is 0.005 to 1000 g /
10 minutes is preferable, and 0.1 to 100 g / min is more preferable.

Next, a typical method for producing a polyolefin polymer having a boronic acid group and a boron-containing group used in the present invention will be described. An olefin polymer having a boronic acid group or a boron-containing group that can be converted to a boronic acid group in the presence of water can be obtained by adding a borane complex and a trialkyl borate to an olefin polymer having a carbon-carbon double bond under a nitrogen atmosphere. An olefin polymer having a boronic acid dialkyl ester group is obtained by reacting an ester, and then obtained by reacting with water or an alcohol. When an olefin polymer having a double bond at a terminal is used as a raw material in this production method, an olefin polymer having a boronic acid group at the terminal or a boron-containing group that can be converted into a boronic acid group by the presence of water can be obtained. When an olefin polymer having a double bond in the side chain or main chain is used as a raw material, a polyolefin polymer having a boronic acid group or a boron-containing group that can be converted to a boronic acid group in the presence of water in the side chain Can be obtained.

Typical production methods of the olefin polymer having a double bond as a raw material include: 1) a method utilizing a trace amount of a double bond present at a terminal of a usual olefin polymer;
2) A process for thermally decomposing an ordinary olefin polymer under oxygen-free conditions to obtain an olefin polymer having a double bond at a terminal; 3) An olefin obtained by copolymerizing an olefin monomer and a diene polymer. A method for obtaining a copolymer of a series monomer and a diene monomer. For 1), a known method for producing an olefin polymer can be used.
Particularly, a production method using a metallocene polymerization catalyst as a polymerization catalyst without using hydrogen as a chain transfer agent (for example, DE40)
30399) is preferred. The method 2) can be obtained by thermally decomposing an olefin-based polymer at a temperature of 300 to 500 ° C. under an oxygen-free condition such as a nitrogen atmosphere or a vacuum condition by a known method (for example, US Pat. No. 2,835,559, 3087922). Regarding 3), a method for producing an olefin-diene copolymer using a known Ziegler catalyst (for example, JP-A-50-44281, DE302127)
3) can be used.

As the borane complex, borane-tetrahydrofuran complex, borane-dimethylsulfide complex, borane-pyridine complex, borane-trimethylamine complex, borane-triethylamine, and the like are preferable. Among these, a borane-triethylamine complex and a borane-trimethylamine complex are more preferred. The amount of the borane complex to be charged is preferably in the range of 1/3 equivalent to 10 equivalent relative to the double bond of the olefin polymer. As the trialkyl borate, lower alkyl borate esters such as trimethyl borate, triethyl borate, tripropyl borate and tributyl borate are preferable. The amount of trialkyl borate to be charged is preferably in the range of 1 to 100 equivalents based on the double bond of the olefin polymer. The solvent does not need to be particularly used, but when used, a saturated hydrocarbon solvent such as hexane, heptane, octane, decane, dodecane, cyclohexane, ethylcyclohexane, and decalin is preferable. The reaction for introducing a boronic acid dialkyl ester group into an olefin polymer having a double bond is performed at a reaction temperature of room temperature to 300 ° C., preferably 100 to 25 ° C.
The reaction is performed at 0 ° C. for a reaction time of 1 to 10 hours, preferably 5 to 5 hours.

As a condition for reacting water or an alcohol, an organic solvent such as toluene, xylene, acetone or ethyl acetate is usually used as a reaction solvent, and water or an alcohol such as methanol, ethanol or butanol; 2-propanediol, 1,3
-Propanediol, neopentyl glycol, glycerin, trimethylolethane, pentaerythritol,
A polyhydric alcohol such as dipentaerythritol is used in an excess of 1 to 100 equivalents or more based on the boronic acid group,
It is obtained by performing the reaction at a temperature of room temperature to 150 ° C. for about 1 minute to 1 day. In addition, the boron-containing group which can be converted into a boronic acid group among the above functional groups refers to a reaction time of 10 minutes to 2 hours in water or a mixed solvent of water and an organic solvent (toluene, xylene, acetone, etc.). , Reaction temperature from room temperature to 150
It means a group that can be converted into a boronic acid group when hydrolyzed under the condition of ° C.

Examples of the thermoplastic resin (a3) used in the present invention include a polyolefin resin, a polyamide resin, a polyester resin, a polycarbonate resin, and a polyvinyl chloride resin. Is preferably used.

These components (a3) are converted to EVOH (a1)
In general, it is difficult to obtain a molded article having excellent flexibility, and it is difficult to obtain a molded article having excellent flexibility. However, in the present invention, such a molded article has poor compatibility with the component (a3), particularly EVOH (a1). Even when the components are blended in the EVOH (a1), a molded article having excellent flexibility can be obtained.
Further, the properties of the component (a3) can be added.

The thermoplastic resin (a3) used in the present invention
Examples of the polyolefin-based resin are copolymers of α-olefins selected from high-density or low-density polyethylene, polypropylene, polybutene-1, etc. and ethylene, propylene, butene-1, hexene-1, etc. As a copolymerization component with these α-olefins, vinyl compounds such as diolefins, N-vinylcarbazole, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, acrylonitrile, vinyl ether, and the like;
Examples include unsaturated carboxylic acids such as maleic acid, acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, and itaconic acid, esters and anhydrides thereof, and those obtained by adding a hydroxyl group or an epoxy group thereto. Specifically, an α-olefin such as a copolymer of a graftable monomer and a polyolefin or an ionomer resin which is a reaction product of an α-olefin / α, β-unsaturated carboxylic acid copolymer and an ionic metal compound is used. 50% by weight
The above copolymers and the like can be mentioned.

The thermoplastic resin (a3) used in the present invention
The polyamide resin is a polymer having an amide bond, for example, polycaproamide (nylon-
6), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,12) Homopolymer, caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / aminoundecanoic acid copolymer (nylon-6 / 11), caprolactam /
ω-aminononanoic acid copolymer (nylon-6,9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer Polymer (nylon-
And copolymers such as 6/6, 6/6, and 12). These polyamide resins can be used alone or in combination of two or more. The thermoplastic resin (a3) is a different type of resin,
For example, a polyolefin-based resin and a polyamide-based resin, specifically, nylon-6 and low-density polyethylene or the like can be used as a mixture of two or more according to the purpose.

[0034] Additives may be added to the resin composition as required. Examples of such additives include antioxidants, plasticizers, heat stabilizers, UV absorbers, antistatic agents, lubricants, colorants, fillers, and other high molecular compounds. Blends can be blended within a range that does not impair the effects of the invention. Specific examples of the additives include the following.

Antioxidants: 2,5-di-tert-butylhydroxine, 2,6-di-tert-butyl-p-cresol, 4,4'-thiobis- (6-tert-butylphenol), 2'-methylene-bis- (4-methyl-6-
t-butylphenol), octadecyl-3- (3 ′,
5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t-butylphenol) and the like. UV absorber: ethylene-2-cyano-3,3'-diphenylacrylate, 2- (2'-hydroxy-5'-
Methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl)
Benzotriazole, 2- (2'-hydroxy-3'-
(t-butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-oxybenzobenzophenone and the like. Plasticizer: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester and the like. Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins,
Polyethylene oxide, carbowax, etc. Lubricants: ethylene bis stearamide, butyl stearate and the like. Colorants: carbon black, phthalocyanine, quinacridone, indoline, azo pigments, red iron, etc. Filler: glass fiber, asbestos, ballastonite, calcium silicate, etc. Many other high molecular compounds can also be blended to such an extent that the effects of the present invention are not impaired.

In the present invention, the composition ratio of each of the components (a1), (a2) and (a3) in the mixed system of (a1) and (a2) is 30 to 85% by weight of EVOH (a1), preferably 45 to 75% by weight, (a2) 70 to 15% by weight, preferably 55 to 25% by weight, and (a1), (a
In the three-component mixed system of 2) and (a3), EVOH (a1)
30 to 85% by weight, preferably 45 to 75% by weight, (a
2) 5 to 60% by weight, preferably 20 to 40% by weight, thermoplastic resin (a3) 10 to 65% by weight, preferably 20 to 4%
0% by weight. In general, it is difficult to mix (a1) and (a3) uniformly, but when (a2) is contained in the resin in an amount of 5% by weight or more, they cause uniform dispersion,
Produces excellent flexibility and barrier properties. Also, (a
If 2) is more than 75% by weight, the barrier properties will be insufficient. Further, when (a1) is more than 85% by weight, flexibility is insufficient.

The resin composition constituting the outer layer (A) can be obtained by a conventionally known method for preparing a thermoplastic resin composition. Examples thereof include a Banbury mixer, a single screw extruder, and a twin screw extruder. It is obtained by melting and kneading other components as needed. In the multilayer pipe of the present invention, the inner layer or the layer (B) near the inner layer
(Hereinafter, both are collectively referred to as “inner layer (B)”). As the polybutene in that case, one or two or more of a homopolymer of polybutene-1, and a graft polymer obtained by copolymerizing the main chain of butene-1 with other vinyl monomers as a minor component in its main chain. Can be used. Other vinyl monomers that can be used as the butene-1 copolymer or graft polymer include ethylene, propylene, diolefin, and unsaturated carboxylic anhydrides such as maleic anhydride. When the inner layer (B) is formed from polybutene, polyethylene, polypropylene, ethylene-vinyl acetate copolymer,
A thermoplastic polymer such as a thermoplastic elastomer such as an ethylene-propylene copolymer elastomer or polyisobutylene rubber may be blended in polybutene.

The cross-linked polyolefin used in the present invention is typically a water-crosslinked polyolefin, a radiation cross-linked polyolefin, or a peroxide cross-linked polyolefin. The water-crosslinkable polyolefin is obtained by copolymerizing a vinyl monomer having a silyl group having a hydrolyzable organic group with an olefin or graft-polymerizing the polyolefin into a water-crosslinkable polyolefin in the presence of a silanol condensation catalyst. , Hot water, steam, etc.
When it is composed of a polyolefin obtained by cross-linking, the water-crosslinkable polyolefin before cross-linking is used to produce the inner pipe or the inner layer (B), the adhesive layer (C) and the outer layer (A). It is preferable that a water-crosslinkable polyolefin constituting the inner layer (B) is crosslinked through water, hot water, steam, or the like inside the inner layer (B) after manufacturing a multi-layer pipe in which is integrated. When the inner layer (B) of the multilayer pipe is composed of a water-crosslinked polyolefin,
55% degree of crosslinking in the water-crosslinked polyolefin inner layer
It is preferable to keep the above.

Although not particularly limited, the above-mentioned silyl group-containing vinyl monomer having a hydrolyzable organic group used for producing a water-crosslinked polyolefin may be, for example, a compound represented by the following general formula:

R-Si- (OR ') 3 wherein R is CH2 = CH- or CH = C (CH3)-
COO- (CH2) n- (n = 1 to 5 is an integer of 1 to 5), and R 'represents a methyl group, an ethyl group, CH3-O-CH2-CH2-, etc.]. A water-crosslinkable polyolefin can be obtained by copolymerizing such a vinyl monomer with an olefin or graft-polymerizing the polyolefin.

When the inner layer (B) is composed of the above-mentioned water-crosslinked polyolefin, an unmodified polyolefin may be blended in an amount which does not impair the object of the present invention. It is preferable that the actual degree of crosslinking be 55% or more.

The peroxide-crosslinked polyolefin used in the present invention is a peroxide. Especially using organic peroxide,
It can be obtained by reacting with a polyolefin in a polymerization tank or an extruder. Specific examples of the peroxide include ketone peroxide, diacyl peroxide, hydroperoxide, dialkyl peroxide, alkyl perester, and the like.

When the inner layer (B) of the multilayer pipe of the present invention is composed of a radiation-crosslinked polyolefin, the radiation-crosslinked polyolefin is mainly composed of polyethylene; polypropylene; ethylene and / or polypropylene, and other components such as butene. Copolymers obtained by copolymerizing one or more of unsaturated carboxylic anhydrides such as olefins, diolefins and maleic anhydride; and other olefins such as butene to a backbone polymer comprising ethylene and / or propylene Or a graft copolymer obtained by graft polymerization of one or more unsaturated carboxylic acid anhydrides such as olefins, diolefins and maleic anhydride.
The purpose of the present invention is to inhibit polyolefins composed of more than one kind, or thermoplastic elastomers such as other thermoplastic polymers, ethylene-vinyl acetate copolymer, ethylene-propylene elastomer, and polyisobutylene rubber, if necessary. A radiation-crosslinked polyolefin blended in an amount not within the range not to be used is preferably used.

When a radiation-crosslinked polyolefin is used as the inner layer (B), the inner layer pipe is manufactured by using the above-mentioned polyolefin or its composition before crosslinking, or the inner layer (B) and the adhesive layer (C) are used. And outer layer (A)
It is preferable to manufacture a multi-layer pipe in which is integrated, and then irradiate the inside of the inner layer (B) with radiation to crosslink.
In this case, it is preferable to use ionizing radiation such as γ-rays, β-rays, electron beams, and X-rays, and the radiation dose is preferably about 5 to 20 Mrad.

Polybutene constituting the inner layer (B);
The cross-linked polyolefin may contain additives such as a lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, a cross-linking agent, a cross-linking auxiliary, a metal chelating agent, an inorganic powder, and a coloring agent, if necessary. Good.

In the multilayer pipe of the present invention, the adhesive layer (C) for bonding the outer layer (A) and the inner layer (B) may be an adhesive capable of firmly bonding the outer layer (A) and the inner layer (B). Any of them can be used, but it is preferable to use a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof (hereinafter, both are referred to as “unsaturated carboxylic acids”). Examples of the polyolefin modified with unsaturated carboxylic acids include one or more of ethylene, propylene, and other α-olefins having 4 to 12 carbon atoms and an unsaturated carboxylic acid, and optionally other copolymerizable olefins. Unsaturated carboxylic acids-modified polyolefins obtained by copolymerization with vinyl monomers (eg, fatty acid vinyl esters such as vinyl acetate, (meth) acrylates such as ethyl acrylate); ethylene, propylene, and others One or two α-olefins having 4 to 12 carbon atoms
Polyolefins obtained by polymerizing at least one species, or olefin copolymers obtained by copolymerizing these olefins and other copolymerizable vinyl monomers similar to those described above,
Examples include a graft copolymer obtained by graft-polymerizing an unsaturated carboxylic acid.

In the above, the unsaturated carboxylic acids used for modifying the polyolefin include monobasic unsaturated carboxylic acids such as acrylic acid, methacrylic acid and methyl methacrylic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid. Basic unsaturated carboxylic acids or anhydrides thereof can be mentioned. These unsaturated carboxylic acids may be used alone or in combination of two or more. Among them, it is particularly preferable to use a polyolefin modified with maleic anhydride.

In the case of a polyolefin modified with an unsaturated carboxylic acid, the modification ratio of the unsaturated carboxylic acid (the unsaturated carboxylic acid is 0.01 to 2% by weight) based on the total weight of the modified polyolefin. When the adhesive layer (C) is composed of a polyolefin modified with an unsaturated carboxylic acid, the modified polyolefin is mixed with an unmodified polyolefin in such an amount that the adhesive strength is not reduced. In the case where such a polymer composition is used, the percentage of modification with the unsaturated carboxylic acids is determined based on the total weight of the polymer composition constituting the adhesive layer. And 0.0
The content is preferably from 0.5 to 5% by weight, more preferably from 0.01 to 2% by weight. Further, an antioxidant (for example, 3,5-t-butyl-4-hydroxytoluene, Irganox 1010, Irganox 1076, or the like) may be added to the adhesive layer (C) as necessary. Good.

The typical layer structure of the multilayer pipe according to the present invention includes an outer layer (A) composed of the above resin composition.
Examples of the structure include an adhesive layer (C) and an inner layer (B) made of polybutene or a crosslinked polyolefin. However, the layer structure of the multilayer pipe of the present invention is not limited to this, and a layer made of the resin composition is used. Constitutes a layer from the outermost layer or the outer layer, a layer composed of the polyolefin for the inner layer constitutes a layer closer to the innermost layer or the inner layer, and the multilayer pipe in which those layers are bonded by an adhesive is within the scope of the present invention. include.

Examples of the multilayer pipe of the present invention include: a multilayer pipe composed of a resin composition layer (A) / adhesive layer (C) / polyolefin layer for inner layer (B); resin composition layer (A) / adhesive Multilayer pipe consisting of layer (C) / resin composition layer (A) / adhesive layer (C) / polyolefin layer (B) for inner layer, resin composition layer (A) / adhesive layer (C) / polyolefin for inner layer A multilayer pipe composed of a layer (B) / adhesive layer (C) / resin composition layer (A) / adhesive layer (C) / polyolefin layer (B) for an inner layer; In the pipe, a plurality of resin composition layers (A) or a plurality of inner polyolefin layers (B) used therein may have the same or different resin contents.

In some cases, the surface of the resin composition layer (A) constituting the outermost layer of the above-mentioned multilayer pipe is further covered with a surface protective layer with or without an adhesive. In this case, as a material of the surface protective layer, a durable polymer such as polybutene, crosslinked polyolefin, polyester, vinyl chloride resin, polyolefin, polystyrene, or polyamide is preferably used. The thickness of the surface protective layer is preferably set to about 5 to 200 μm.

The outer diameter, the inner diameter, and the wall thickness of the multilayer pipe of the present invention can be appropriately selected according to the respective applications and are not particularly limited. For example, the outer diameter is 5 to 50 mm,
In the case of a multi-layer pipe having an inner diameter of 3 to 40 mm and a wall thickness of 1 to 5 mm, the thickness of the layer (A) made of the resin composition is about 15 to 300 μm, preferably 50 to 1 μm.
50 μm, the thickness of the adhesive layer (C) is 2 to 10 μm, preferably 4 to 16 μm, and the thickness of the layer (B) composed of the polyolefin for the inner layer is 1000 to 4500 μm, preferably 15 μm.
It is good to be 00-3500micro.

The multi-layer pipe of the present invention is manufactured by preparing a multi-layer pipe having the above-mentioned outer layer (A), adhesive layer (C) and inner layer (B). Irradiation such as radiation, gamma rays, electron beams, and X-rays is also free. When a surface protective layer is further provided on the surface of the outer layer (A), irradiation can be performed from outside the surface protective layer.

The method for producing the multilayer pipe of the present invention includes:
There is no particular limitation, and any method can be adopted. Examples of the production method include: (1) melt-extruding an inner pipe using an inner polyolefin, and forming the inner pipe into a water-crosslinked polyolefin;
Radiation-crosslinked polyolefin or, if formed from peroxide-crosslinked polyolefin, after water or radiation cross-linking, melt-extruding and coating an adhesive layer on the outer surface, and further melt-extruding a resin composition thereon. Method of irradiating radiation from the outer layer after producing a multilayer pipe by coating: (2) melt-extruding the inner pipe using polyolefin for the inner layer, melt-extruding and coating the adhesive layer on the outer surface, and further coating After the resin composition is melt-extruded and coated, it is irradiated with radiation from the outside, and when the inner layer pipe is formed of a water-crosslinkable polyolefin or a radiation crosslinkable polyolefin, the inner layer pipe is subjected to water crosslinking or radiation crosslinking from the outer layer side. (3) Resin composition (a), adhesive and inner layer A method of irradiating radiation from the outside of the multilayer pipe after co-extrusion with the olefin (b) to produce a multilayer pipe (in this case, when the inner layer is formed of a water-crosslinkable polyolefin or a radiation-crosslinkable polyolefin). The cross-linking of the inner layer with water or radiation can be performed simultaneously with the irradiation of radiation from the outer layer, or before or after the irradiation of radiation from the outer layer).

When the surface of the outer layer made of the resin composition is further covered with a surface protective layer, the surface protective layer can be formed before or after irradiation with radiation from the outer layer side. The surface protective layer is formed by extrusion coating, by coextrusion of the outer layer (A), adhesive layer (C) and inner layer (B) of the multilayer pipe, by applying a solution in which the material for surface protection is dissolved to the multilayer pipe. Any method, such as a method of applying the composition to the surface of the substrate, can be adopted.

The multi-layer pipe of the present invention is excellent in workability and durability, and also excellent in barrier properties and heat resistance against gases such as oxygen gas, and thus is a pipe for supplying, circulating, and discharging hot water or hot water. And is preferably used as a pipe for circulating hot water or hot water in floor heating, central heating and the like. However, the present invention is not limited thereto, and can be effectively used as pipes for various liquids and gases by utilizing its excellent gas barrier properties, heat resistance, workability, workability, and the like.

[0057]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the following Examples and Comparative Examples, the bending workability (the stress required for bending, the degree of flattening at the bent portion and the appearance of the bent portion) and the oxygen barrier property of the multilayer pipe manufactured in each example are as follows. Was measured or evaluated.

(1) Bending workability: The multilayer pipe obtained in each example was cut into a length of 25 cm, and this was cut using a bending machine (manufactured by Shimadzu Corporation; Autograph) with a radius of curvature of 100.
mm and the stress required at that time was measured. (2) Degree of flattening at the bent portion: the maximum diameter (outer diameter) (Rm) at the bent portion when the bending process of (1) is performed.
ax) and the minimum diameter (outer diameter) (Rmin) are measured using calipers, and the ratio of the minimum diameter to the maximum diameter = (Rmin
/ Rmax) and the degree of flattening was evaluated. (Rmin
The closer the value of (/ Rmax) is to 1.00, the less the flattening at the bent portion is, and the better the bending workability is. (3) Appearance of the bent portion: The color tone of the bent portion was visually observed, and the case where the discoloration such as whitening did not occur in the bent portion was evaluated as good (、), and the case where the color was whitened was evaluated as poor (×). did.

Oxygen barrier properties of the multi-layer pipe: (1) Before passing hot water: One end of the multi-layer pipe having a length of about 3 m is sealed with a silicone rubber stopper and an adhesive, and the other end is an oxygen permeation measuring device. (Modern Control: O
X-TRAN). (Atmosphere 20 ° C-
(65% RH) (2) After passing through hot water (95 ° C.): After cooling the multilayer pipe for about 1 hour, the amount of oxygen permeation was measured by the same operation as before passing through the hot water.

Synthesis Example 1 Synthesis of ultra-low-density polyethylene having a boronic acid ethylene glycol ester group at a terminal: A super-low-density polyethylene @ MI 7 g / 10 min (210 ° C., load 2160 g) density 0.89, terminal double bond amount 0.048 meq / g ／ 1
After 000 g and 2500 g of decalin were charged and degassed by reducing the pressure at room temperature, the atmosphere was replaced with nitrogen. To this, 78 g of trimethyl borate and 5.8 g of a borane-triethylamine complex were added, and after reaction at 200 ° C. for 4 hours, a distillation apparatus was attached, and 100 ml of methanol was slowly added dropwise. After the completion of methanol dropping, by distillation under reduced pressure,
Low boiling impurities such as methanol, trimethyl borate and triethylamine were distilled off. Further, 31 g of ethylene glycol was added, and after stirring for 10 minutes, reprecipitated in acetone,
By drying, an ultra-low density polyethylene (boronic acid-modified polyethylene) (B boronic acid-modified polyethylene) having a boronic acid ethylene glycol ester group content of 0.027 meq / g and an MI of 5 g / 10 min.
-PE).

Example 1 (1) EVOH ｛ethylene content 27 mol%, saponification degree 9
9.6%, melt index 2.0 g / 10 min (21
0 ° C., 2160 g load)} and the ultra-low density polyethylene having a boronic acid ethylene glycol ester group at the end obtained in Synthesis Example 1 (hereinafter abbreviated as B-PE) in a mixing ratio shown in Table 1 at a mixing ratio of 30 mmφ twin screw extruder. And melt-kneaded at 210 ° C. to form pellets. (2) Water-crosslinkable polyethylene (“Mordex S-141” manufactured by Sumitomo Bakelite Co., Ltd.) for the inner layer (B), maleic anhydride-modified polyethylene (“Admer NF500” manufactured by Mitsui Petrochemical Co., Ltd.) for the adhesive layer and the above (1) The resin composition (a) prepared in (1) is supplied to a co-extrusion molding machine for producing a multi-layer pipe, and simultaneously melt-extruded and laminated to obtain the resin composition (a).
A multi-layer pipe having an outer diameter of 20 mm and comprising an outer layer / adhesive layer / inner layer of water-crosslinkable polyethylene was manufactured. The thickness of the outer layer / adhesive layer / inner layer in the obtained multilayer pipe is 100 μm.
/ 50μ / 1850μ. The bending workability and oxygen barrier property of this multilayer pipe were measured or evaluated by the above-mentioned methods, and the results shown in Table 1 were obtained.

Examples 2 to 5 Instead of the resin composition comprising EVOH and B-PE,
Except that the resin composition was adjusted by the resin composition and the compounding ratio shown in Table 1, or the type of the inner layer (B) was changed,
A multilayer pipe was prepared under the same conditions as in Example 1, and these measurements were performed.

Example 6 Water vapor (temperature: 150 ° C .; pressure: 4 kg / cm 2) was passed through the inside of the multilayer pipe obtained in Example 1 (2) for 2 minutes to crosslink the inner layer, and then radiation was emitted from the outer layer by 10 Mrad. In the same manner as in Example 1 except that the mixture was irradiated with the above dose and adjusted to the compounding ratio of the resin composition in Table 1. A multilayer pipe was made and these measurements were made.

Comparative Examples 1 to 4 Instead of the resin composition comprising EVOH and B-PE,
Except that the resin composition was adjusted according to the resin composition and the compounding ratio shown in Table 2, or the type of the inner layer (B) was changed,
A multilayer pipe was prepared under the same conditions as in Example 1, and these measurements were performed.

Comparative Example 5 Water vapor (temperature: 150 ° C .; pressure: 4 kg / cm 2) was passed through the inside of the multilayer pipe obtained in Example 1 (2) for 2 minutes to crosslink the inner layer, and then 10 Mrad of radiation was emitted from the outer layer. In the same manner as in Example 1 except that the composition was irradiated with the above dose and adjusted to the mixing ratio of the resin composition in Table 2. A multilayer pipe was made and these measurements were made.

Resin Ac-PE: water-crosslinkable polyethylene {“Mordex S-141” manufactured by Sumitomo Bakelite Co., Ltd., polybutene “WITRON 4101” manufactured by Witco Chemical Co., Ltd., PE: polyethylene} MI = 0.20 g / 10 min. (21
0 ° C, 2160g load) "HZ5100" manufactured by Mitsui Petrochemical
B "｝, PA: 6-nylon ｛MI = 7 g / 10 min (2
30 ° C, 2160g load) Ube Industries “1022B” 部

[0067]

[Table 1]

[0068]

[Table 2]

From the results shown in Table 1 above, the multilayer pipes of the present invention of Examples 1 to 5 are excellent in bending workability, require only a small stress during bending, have a low degree of flattening in the bent portion, and No whitening occurs, and 9
It can be seen that even if hot water at 5 ° C. is passed through the pipe, there is no decrease in the oxygen barrier property, and the initial good oxygen barrier property can be maintained. On the other hand, the multilayer pipes of Comparative Examples 1 to 5 have good oxygen barrier properties at first, but when hot water of 95 ° C. is passed for a long period of time, the oxygen barrier properties are remarkably reduced, and the pipes withstand use. It turns out that it is gone.

[0070]

The multilayer pipe of the present invention has excellent properties such as durability, corrosion resistance, flexibility, and heat resistance, has excellent gas barrier properties without passing oxygen gas and other gases, and has a long life. Their performance does not decrease even through hot water or hot water. And since the gas such as oxygen gas outside the pipe does not dissolve in the warm water or hot water flowing through the pipe through the wall of the multilayer pipe due to its excellent gas barrier property, the multilayer pipe is attached, for example, heat exchange Corrosion of metal parts in various facilities such as a vessel and a hot water circulation pump can be suppressed. Further, the multi-layer pipe of the present invention is easy to form and process, for example, when the pipe is bent when installed in various facilities, cracks and whitening do not occur at the portion, so that the workability is excellent, and Good performance can be maintained for a long time.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-186310 (JP, A) JP-A-7-329252 (JP, A) JP-A-7-300123 (JP, A) 340783 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 F16L 9/00-11/24

Claims (5)

(57) [Claims] (A1) An ethylene-vinyl alcohol copolymer (a1) and at least one selected from a boronic acid group, a borinic acid group, a boronic acid group and a boron-containing group which can be converted into a borinic acid group in the presence of water. An outer layer or an outer layer made of a resin composition containing a polyolefin (a2) having one functional group, (B) an inner layer or an inner layer made of polybutene or crosslinked polyolefin, and (C) bonding these layers A multilayer pipe having an adhesive layer. 2. (A) an ethylene-vinyl alcohol copolymer (a1), a boronic acid group, a borinic acid group, at least one selected from a boronic acid group and a boron-containing group which can be converted to a borinic acid group in the presence of water. Outer layer or outer layer made of resin composition containing polyolefin (a2) having one functional group and thermoplastic resin (a3), (B) Inner layer or inner layer made of polybutene or crosslinked polyolefin
A multi-layer pipe comprising: a further layer and (C) an adhesive layer bonding the layers. 3. The thermoplastic resin (a3) is a polyolefin.
3. The resin according to claim 2, wherein the resin is a polyamide resin or a polyamide resin.
Multi-layer pipe. 4. In the presence of a boronic acid group, a borinic acid group, and water
Boronate groups and boron-containing groups that can be converted to borinic acid groups
At least one functional group selected is a boronic ester group
The multilayer pie according to any one of claims 1 to 3, wherein
H. 5. The method according to any one of claims 1 to 4, wherein
Hot or hot water circulation pipe consisting of layered pipes.