JP2003097772A - Multiple layer pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple layer pipe, which is superior in gas barrier property, low temperature cracking resistance, heat shrinkage following property, heat aging resistance, and long-run molding property. SOLUTION: This pipe includes at least one layer of resin composition comprising ethylene-vinyl acetate copolymer saponificate (A), polyamide base resin (B) whose melting point is 160 deg.C or less, and an amide group containing antioxidant (C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer pipe, and more specifically, gas barrier properties, low temperature crack resistance,
The present invention relates to a multi-layer pipe excellent in heat shrinkage followability, heat aging resistance, and long-run moldability.

[0002]

2. Description of the Related Art Conventionally, iron or copper pipes have been widely used as hot water pipes used for central heating by a hot water circulation method, particularly floor heating equipment. However, in recent years, resin pipes such as polyethylene, polypropylene, and polybutene have come to be used in place of metal pipes because of advantages such as price and construction. However, in the case of such a resin pipe, since the resin does not have a sufficient oxygen barrier property, a large amount of oxygen invades the hot water in the pipe and corrodes the metal parts such as the heat exchanger and the pump. There is a fear. Therefore, in order to prevent such invasion of oxygen, a multilayer pipe using a saponified ethylene-vinyl acetate copolymer having excellent gas barrier properties (hereinafter abbreviated as EVOH) has been proposed.

However, EVOH is a resin that is extremely rigid as compared with polyolefin resins such as polyethylene and polybutene, so that the following problems may occur. (1) When connecting a multi-layer pipe to a joint made of metal, the diameter of the pipe is expanded by a dedicated expansion jig, but at that time, cracks may occur in the EVOH layer, and the oxygen barrier property may deteriorate. is there. Especially when working in an area where the outside temperature is extremely low or in an environment in a season, cracks are likely to occur (insufficient low temperature crack resistance). (2) A temperature change occurs in the multilayer pipe when hot water flows and when hot water does not flow. EVO is caused by shrinkage (dimensional change) of the polyolefin resin due to the temperature change.
H may not be able to follow, cracks may occur in the EVOH layer during long-term use, and the oxygen barrier properties may deteriorate. In particular, cracks are likely to occur in the extremely bent portion of the multilayer pipe (insufficient thermal shrinkage followability).

As a solution to this problem, Japanese Patent Laid-Open No. 10-230
JP-A-2000-249263 describes a multilayer pipe having a layer structure of a resin composition layer / adhesive layer / polybutene or a crosslinked polyolefin layer composed of EVOH and an ethylene- (meth) acrylic acid copolymer. The publication describes a multilayer pipe having a resin composition layer composed of EVOH, a polyamide resin, an olefin-unsaturated carboxylic acid copolymer or a metal salt thereof and a thermoplastic resin having a specific solubility parameter, The applicant also
A multilayer pipe including a resin composition layer composed of EVOH, a thermoplastic resin exhibiting a specific tensile elongation at break, a phenol compound, a phosphorus compound, or an amine compound has been proposed (JP-A-11-12398).

[0005]

However, JP-A-10-230555 and JP-A-2000-2492.
In the technology disclosed in Japanese Patent Laid-Open No. 63, although the effect of improving the low temperature crack resistance is recognized to some extent, the heat shrinkage followability is insufficient, and the heat aging resistance required for the hot water circulation pipe for floor heating is also taken into consideration. However, it has been found that there is room for improvement in the long-run formability of the pipe.
It has been found that the technology disclosed in Japanese Patent Publication No. 98 has a large effect of improving the heat shrinkage followability and the heat aging resistance, but there is room for improvement in the low temperature crack resistance.

[0006]

The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, EVOH (A) and a polyamide resin (B) having a melting point of 160 ° C. or less (B ) And an amide group-containing antioxidant (C) at least one layer of a resin composition, a multi-layer pipe having gas barrier properties, low temperature crack resistance, heat shrinkage followability, heat aging resistance, long run moldability. It was found that all the characteristics of the above can be satisfied, and the present invention has been completed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.

The multi-layer pipe of the present invention comprises EVOH (A),
The EVOH (A) includes at least one resin composition layer containing a polyamide resin (B) having a melting point of 160 ° C. or less and an amide group-containing antioxidant (C).
Is not particularly limited, but the ethylene content is 10
~ 70 mol% (further 20-60 mol%, especially 25
.About.50 mol%) and a saponification degree of 90 mol% or more (further 95 mol% or more, particularly 99 mol% or more) are preferably used. When the ethylene content is less than 10 mol%, The gas barrier property and melt moldability deteriorate, and conversely 70
When it exceeds mol%, sufficient gas barrier properties cannot be obtained, and when the saponification degree is less than 90 mol%, gas barrier properties, thermal stability, moisture resistance and the like are deteriorated, which is not preferable.

Further, the intrinsic viscosity of the EVOH (A) (30% in a mixed solvent of 85% by weight of phenol and 15% by weight of water,
Measured at 0.6 ° C.) is 0.6 to 1.5 dl / g (further more than 0.
7-1.3 dl / g, especially 0.8-1.2 dl / g)
Is preferable, and the viscosity is less than 0.6 dl / g or 1.5.
Exceeding dl / g is not preferable because the extrusion moldability may become unstable.

Further, the melt flow rate (MFR) of the EVOH (A) (210 ° C., load 2160 g) is 0.
5-100g / 10 minutes (further 1-50g / 10 minutes,
Particularly, 3 to 35 g / 10 minutes) is preferable, and when the melt flow rate is smaller than the above range, the inside of the extruder may be in a high torque state during molding, and extrusion processing may be difficult. If it is larger than this, the thickness accuracy of the EVOH layer of the obtained multilayer pipe may be deteriorated, which is not preferable.

The EVOH (A) is obtained by saponification of an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer is obtained by any known polymerization method such as solution polymerization, suspension polymerization, It may be produced by emulsion polymerization or the like, and saponification of an ethylene-vinyl acetate copolymer may be carried out by a known method.

Further, in the present invention, an ethylenically unsaturated monomer which can be copolymerized may be copolymerized within a range that does not impair the effects of the present invention. Examples of such a monomer include propylene and 1-butene. , Olefins such as isobutene, acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid,
Unsaturated acids such as (anhydrous) maleic acid and (anhydrous) itaconic acid or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, 1 to 1 carbon atoms
8, N-alkylacrylamide, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof, methacrylamide, methacrylamide, and 1 to 18 carbon atoms. N-alkylmethacrylamide, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidopropyldimethylamine or its acid salt or its quaternary salt, and other N-vinylpyrrolidone. N-vinylamides such as N-vinylformamide and N-vinylacetamide,
Vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide. Vinyl halides such as trimethoxyvinylsilane, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl)-
Examples thereof include ammonium chloride and acrylamido-2-methylpropanesulfonic acid. Further, post-modification such as urethanization, acetalization, cyanoethylation, etc. may be carried out within a range not impairing the gist of the present invention.

It is also possible to use two or more different EVOHs as the EVOH (A), in which case the ethylene content is 5 mol% or more (further 5 to 25 mol%, particularly 8 to 20 mol%). Mol%) and / or the saponification degree is 1 mol% or more (further 1 to 15 mol%, especially 2).
EVOH which is different and / or has a MFR ratio of 2 or more (more preferably 3 to 20, especially 4 to 15).
The use of the blended product is useful because the flexibility and the film thickness stability are further improved while maintaining the gas barrier property. Two or more different EVOH (blend)
The method for producing is not particularly limited, and for example, EVA before saponification is used.
Method of saponifying each paste after mixing, each E after saponification
Examples thereof include a method of mixing a VOH alcohol or a mixed solution of water and an alcohol, and a method of mixing and kneading each EVOH.

Further, the above polyamide resin (B) is
It is necessary that the melting point be 160 ° C. or lower, and the effect of the present invention cannot be obtained even if a polyamide-based resin having a melting point exceeding 160 ° C. is used.
A temperature of 150 ° C is preferable, and a temperature of 80 to 140 ° C is particularly preferable. Here, the melting point means a differential scanning calorimeter (DS
It is a melting peak temperature (° C) measured at a temperature rising rate of 10 ° C / min using C).

Specific examples of the polyamide resin (B) include polycapramide (nylon 6) and poly-
ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecane amide (nylon 11), polylauryl lactam (nylon 1)
2), polyethylenediamine adipamide (nylon 2
6), polytetramethylene adipamide (nylon 4
6), polyhexamethylene adipamide (nylon 6
6), polyhexamethylene sebacamide (nylon 61
0), polyhexamethylene dodecamide (nylon 61
2), polyoctamethylene adipamide (nylon 8,
6), polydecamethylene adipamide (nylon 10
8), caprolactam / lauryllactam copolymer (nylon 6/12), caprolactam / ω-aminononanoic acid copolymer (nylon 6/9), caprolactam / hexamethylene diammonium adipate copolymer (nylon 6/66), Lauryl lactam / hexamethylene diammonium adipate copolymer (nylon 12/6
6), ethylenediamine adipamide / hexamethylene diammonium adipate copolymer (nylon 26/6
6), caprolactam / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon 66/610), ethylene ammonium adipate / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon 6 / 66/610), polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, hexamethylene isophthalamide / terephthalamide copolymer or polyamide resins modified with aromatic amines such as methylenebenzylamine and metaxylenediamine. And metaxylylene diammonium adipate, etc., among these types,
Those having a melting point of 160 ° C. or lower are used.

The method for keeping the melting point of the polyamide resin at 160 ° C. or lower is not particularly limited, but industrially, it is preferable to use a copolymer in a specific ratio among the above polyamide resins. Specific examples of combined nylon include nylon 6/12, nylon 6/69, nylon 6
/ 66/610, Nylon 6/66/610/12, Nylon 6/66/610/11, etc. and aromatic amine modified products thereof. Specific commercial names are "Amilan CM4000". , "Amilan CM800
0 ”,“ Amilan CM6541-X3 ”,“ Amilan C
"M831", "Amilan CM833" (all manufactured by Toray), "Elvamide 8061", "Elvamide 8062"
"S", "Elvamide 8066" (above made by DuPont Japan), "Grillon CF6S", "Grillon CF62"
BS ”,“ Grillon CA6E ”,“ Grillon XE338 ”
1 ”,“ Grillon BM13SBG ”(above, manufactured by MMS Japan),“ UBE7128B ”,“ UBE7028 ”
B ”(above, manufactured by Ube Industries, Ltd.) and the like.

Further, the polyamide resin (B) was measured by using a differential scanning calorimeter (DSC) (heating rate 10 ° C. /
The heat of fusion (ΔH) to be min) is preferably 80 J / g or less (further 5 to 70 J / g, particularly 10 to 60 J / g), and when the heat of fusion (ΔH) exceeds 80 J / g. However, the resulting multi-layer pipe is not preferable because it may have insufficient low temperature crack resistance, heat shrinkage followability, long-run moldability and the like. Heat of fusion of polyamide resin (ΔH)
Is not particularly limited, but industrially, the degree of polymerization in the polyamide resin, the molecular weight,
It can be preferably carried out by controlling the molecular weight distribution, the content of low molecular weight components, the water content, the amount of residual monomers and the like.

Further, the melt flow rate (MFR) of the polyamide resin (B) (210 ° C., load 2160).
g) is 1 to 100 g / 10 minutes (further 3 to 80 g /
10 minutes, especially 5 to 50 g / 10 minutes) is preferable,
Even if the FR is out of the range, the resulting multi-layer pipe may have insufficient low-temperature crack resistance, heat shrinkage followability, long-run moldability, etc., which is not preferable. The method for adjusting the MFR of the polyamide resin to the above range is not particularly limited, but industrially, the polymerization degree of the polyamide resin, the molecular weight, the molecular weight distribution, the content of the low molecular weight component, the water content, the residual monomer content, etc. It can be suitably performed by controlling.

In the present invention, as the polyamide resin (B), the structure, composition, melting point, heat of fusion, molecular weight (MF
It is also possible to use two or more types of polyamide-based resins having different R) and different molecular weight distributions in combination.

Further, as the above-mentioned antioxidant (C),
It is necessary that it contains an amide group,
Even if an antioxidant containing no amide group is used, the effect of the present invention cannot be sufficiently obtained. The mechanism of action is not clear, but a synergistic effect is exhibited by the interaction of the hydroxyl group of EVOH (A) and the amide group of the polyamide resin (B) and the antioxidant (C), and low temperature crack resistance. It is presumed that the heat shrinkage followability and the heat aging resistance are improved.

The antioxidant (C) is not particularly limited as long as it contains an amide group, and it is a hindered phenol-based antioxidant, phosphite-based antioxidant, thioether-based antioxidant, Examples thereof include hindered amine-based antioxidants, benzotriazole-based antioxidants, benzophenone-based antioxidants, etc., and hindered phenol-based antioxidants are preferable in that they are particularly excellent in the effect of heat aging resistance. N'-tetramethylenebis (3,5-di-t-butyl-4-hydroxyphenylethylamide), N, N'-tetramethylenebis (3,3
5-di-t-butyl-4-hydroxyphenyl-n-propylamide), N, N'-tetramethylenebis (3,3
5-di-t-butyl-4-hydroxyphenyl-n-butylamide), N, N'-tetramethylenebis (3,5
-Di-t-butyl-4-hydroxyphenylisobutyramide), N, N'-tetramethylenebis (3,5-di-t-butyl-4-hydroxyphenyl-n-heptylamide), N, N'- Hexamethylenebis (3,5-di-t-butyl-4-hydroxyphenylethylamide), N, N'-hexamethylenebis (3,5-di-t
-Butyl-4-hydroxyphenyl-n-propylamide), N, N'-hexamethylenebis (3,5-di-t
-Butyl-4-hydroxyphenyl-n-butylamide), N, N'-hexamethylenebis (3,5-di-t
-Butyl-4-hydroxyphenylisobutyramide), N, N'-hexamethylenebis (3,5-di-t
-Butyl-4-hydroxyphenyl-n-heptylamide), N, N'-octamethylenebis (3,5-di-t
-Butyl-4-hydroxyphenylethylamide),
N, N'-octamethylenebis (3,5-di-t-butyl-4-hydroxyphenyl-n-propylamide),
N, N'-octamethylenebis (3,5-di-t-butyl-4-hydroxyphenyl-n-butyramide),
N, N'-octamethylenebis (3,5-di-t-butyl-4-hydroxyphenylisobutyramide), N,
N'-octamethylene bis (3,5-di-t-butyl-
4-hydroxyphenyl-n-heptylamide), N,
N'-decamethylene bis (3,5-di-t-butyl-4
-Hydroxyphenylethylamide), N, N'-decamethylenebis (3,5-di-t-butyl-4-hydroxyphenyl-n-propylamide), N, N'-decamethylenebis (3,5- Di-t-butyl-4-hydroxyphenyl-n-butylamide), N, N'-decamethylene bis (3,5-di-t-butyl-4-hydroxyphenylisobutyramide), N, N'-decamethylene Bis (3,5-di-t-butyl-4-hydroxyphenyl-
n-heptylamide) and the like.

In the present invention, the antioxidant (C) is an antioxidant (C) having a different structure, composition, molecular weight, etc.
It is also possible to use two or more types in combination. The antioxidant (C) may be in any form such as powder, granules, liquid, paste and emulsion.

The content ratio of the above (A) to (C) is not particularly limited, but the content weight ratio of (A) and (B) (A /
B) is 50/50 to 99/1 (further 60/40 to
97/3, especially 70/30 to 95/5),
When the weight ratio is less than 50/50, the gas barrier property may be insufficient, and conversely, when it is more than 99/1, the low temperature crack resistance and the heat shrinkage followability may be insufficient. There is not preferable. When two or more polyamide-based resins (B) having different structures, compositions, melting points, heats of fusion, molecular weights (MFR), and molecular weight distributions are used together, the total weight thereof is the above. It should be in the range of.

Further, (C) is 0.01 to 3 parts by weight (further 0.05 to 2 parts by weight, particularly 0.1 to 1) based on 100 parts by weight of the total amount of (A) and (B). (Parts by weight) so that the weight is 0.0
When it is less than 1 part by weight, heat aging resistance may be insufficient, and when it is more than 3 parts by weight, the appearance, low temperature crack resistance and heat shrinkage followability of the obtained multilayer pipe are deteriorated. May occur, which is not preferable. When two or more kinds of antioxidants (C) having different structures, compositions, and molecular weights are used together as the antioxidant (C), the total weight may be within the above range.

The above-mentioned resin composition comprising (A) to (C) may be prepared by blending the components (A) to (C). Specifically, the components (A) to (C) are blended. Method of melt kneading all at once, method of melt kneading components (A) and (B) and then adding component (C) and further melt kneading, after adding component (C) to component (A) (B)
A method of melt-kneading the components, a method of adding the component (C) to the component (B) and then melt-kneading the component (A),
A method in which the components (C) are added to both the components (A) and (B) and then the components are melted and kneaded, and the components (A) to (C) are uniformly dissolved and mixed in a solvent capable of being dissolved. Examples thereof include a method of removing the solvent, and the methods of and are preferably used. The method will be described in more detail, but the method is not limited thereto.

Examples of the method for melt-kneading the components (A) to (C) at once include, for example, a kneader ruder, an extruder,
Although it can be performed using a known kneading device such as a mixing roll, a Banbury mixer, a plastomill,
Usually, it is industrially preferable to use a single-screw or twin-screw extruder, and it is also preferable to provide a vent suction device, a gear pump device, a screen device, and the like, if necessary. In particular, in order to remove water and by-products (pyrolysis low-molecular-weight substances, etc.), one or more vent holes are provided in the extruder to suck under reduced pressure, and to prevent oxygen from entering the extruder. For this purpose, by continuously supplying an inert gas such as nitrogen into the hopper, it is possible to obtain a resin composition of excellent quality in which thermal coloring and thermal deterioration are reduced.

There are no particular restrictions on the supply of (A) to (C) to the extruder, 1) solid (A),
(B) and (C) are collectively mixed and melt-kneaded, 2) Solid (B) and (C) are added to melted (A) and melt-kneaded, 3) Melting Method of adding solid (A) and (C) to melted state (B) and melt kneading, 4) Adding solid (C) to melted state (A) and (B) and melt kneading 5) Method of adding solid (B) to melted state (A) and (C) and melt kneading, 6) Solid state (A) of melted state (B) and (C) And melt-kneading, and 7) a method of mixing (A), (B) and (C) in a molten state and melt-kneading, and the like. Among them, 1) and 4) However, it is practical in terms of the simplicity of the device and the cost of the blended product.

As a method of melt-kneading the component (B) after the component (C) is contained in the component (A), a) the component (A) and the component (C) are melt-kneaded and then the component (B) is added. Melt-kneading method, b) Component (C) is added to and mixed with solution-like (A) component, the solvent is removed, and then (B) component is melt-kneaded, c) (A) before saponification The component (C) may be added to the component (), mixed, and then saponified, and then the component (B) may be melt-kneaded.
The method (2) is preferable because it has excellent dispersibility of the component (B) and can sufficiently exert its addition effect.

When the EVOH (A) is made into a solution, it may be dissolved in a solvent capable of dissolving the EVOH (A), and the solvent and the method thereof are not limited, but the solvent is methanol, ethanol or propanol. ,
Phenol, dimethyl sulfoxide (DMSO),
Examples thereof include solvents such as dimethylformamide (DMF) and hexafluoroisopropanol (HFIP), and aqueous solutions (mixed solvent) containing these solvents. In the case of the aqueous solution, the solvent / water weight mixing ratio is 90 / 10-3
It is preferably 0/70.

The amount of EVOH (A) contained in the solution is 2 to 60% by weight (further 5 to 60% by weight, especially 1% by weight).
0 to 55% by weight) is preferable, and if the content of EVOH (A) is out of the above range, dispersibility of the antioxidant (C) may be insufficient, which is not preferable. Further, as a method for preparing the solution, E containing no antioxidant (C) is used.
Dissolve VOH (A) powder, pellets, etc. in a solvent or a solvent / water mixed solvent to a predetermined concentration, or use EV
An appropriate amount of a solvent, water or a mixed solvent thereof is added to a solvent solution of EVOH (A) after saponification during OH (A) production, or precipitation during precipitation of EVOH (A) or water-containing EVOH after washing with water A method of dissolving the pellet of (A) in a solvent or a mixed solvent of solvent / water so as to have a predetermined concentration and liquid composition can be mentioned, and the method suitable for production can be adopted.

Then, the EVOH obtained as described above
The solution (A) contains the antioxidant (C), but the content is not particularly limited. For example, a method of directly adding the antioxidant (C) to the solution, or an antioxidant (C) It is possible to employ a method in which (1) is dispersed in an aqueous solution of about 0.1 to 10% by weight or a water / solvent mixed solution and then added. At this time, the amount of the antioxidant (C) contained in the solution of EVOH (A) is EVOH.
(A) 0.001 to 10 parts by weight (more preferably 0.01 to 5 parts by weight, particularly 0.1 to 2 parts by weight) per 100 parts by weight.
If the amount is outside the above range, the dispersibility of the antioxidant (C) may be insufficient, which is not preferable. Further, EVO when containing an antioxidant (C)
The temperature of the H (A) solution is 10 to 100 ° C. (further, 20 to
60 ° C) is preferred, and below 10 ° C, antioxidant (C)
However, if the temperature exceeds 100 ° C., it is difficult to handle the solution, which is disadvantageous in production.

E containing the antioxidant (C) obtained above
The VOH (A) solution is preferably pelletized by extruding it into a coagulating liquid in a strand form and precipitating it. The solution may be used as it is, or the solution may be appropriately concentrated or diluted, or It is also possible to add water to prepare the solution for strand production.
At this point, saturated aliphatic amides (eg stearic acid amide etc.), unsaturated fatty acid amides (eg oleic acid amide etc.), bis fatty acid amides (eg ethylene bis stearic acid amide etc.), fatty acid metal salts (eg calcium stearate etc.) , Low molecular weight polyolefin (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000,
Or a lubricant such as low molecular weight polypropylene), an inorganic salt (such as hydrotalcite), a plasticizer (such as an aliphatic polyhydric alcohol such as ethylene glycol, glycerin, or hexanediol), a colorant, an antibacterial agent, etc. May be. EVO in adjusted EVOH (A) solution
The concentration of H (A) is preferably 10 to 60% by weight,
More preferably, it is 15 to 50% by weight, and if the concentration is less than 10% by weight, coagulation in the coagulation liquid becomes difficult, and conversely 6%.
If it exceeds 0% by weight, the porosity of the obtained pellets is lowered and the thermal stability during molding is adversely affected, which is not preferable.

As the coagulating liquid for extruding and depositing the EVOH (A) solution in the form of strands, water or a water / alcohol mixed solvent, aromatic hydrocarbons such as benzene, ketones such as acetone and methyl ethyl ketone, and dipropyl ether are used. And the like, and organic acid esters such as methyl acetate, ethyl acetate, and methyl propionate are used, and water or a water / alcohol mixed solvent is preferable. As the alcohol, alcohols such as methanol, ethanol and propanol are used, but methanol is preferably used. The temperature at which the EVOH (A) solution is brought into contact with the coagulating liquid is preferably -10 to 40 ° C, more preferably 0 to 20 ° C.
Is. Since the above-mentioned organic solvent is a non-solvent for the saponified product, there is almost no risk of the saponified product being dissolved in the coagulating liquid to cause resin loss, but operation at a temperature as low as possible is safe. E
The VOH (A) solution can be discharged by a nozzle having an arbitrary shape.
The shape of the nozzle is extruded in a strand shape into the coagulating liquid as described above, but the shape of the nozzle is not particularly limited, but a cylindrical shape is preferable, and its length is preferably 1 to 100 cm, and further 3 to 30 cm. , The inner diameter is 0.1-1
0 cm is preferable, and 0.2 to 5 cm is more preferable.

Thus, the EVOH (A) (solution) containing the antioxidant (C) is extruded from the nozzle in the form of a strand, but the number of strands is not necessarily one, and it may be between several and several hundreds. Can be extruded with any number of.

Then, the EV extruded in a strand shape
OH (A) is sufficiently solidified and then cut, pelletized, and then washed with water. The shape of such pellets has a diameter of 2 to 8 in the case of a cylindrical shape in view of workability during molding and handling.
mm, length 2-8 mm (further 2-5 respectively)
In the case of a spherical shape, a diameter of 2 to 8 mm (further, 2 to 5 mm) is practical. Also,
As the washing condition, the pellets are washed in a water bath at a temperature of 10 to 60 ° C. By such washing with water, oligomers and impurities in EVOH (A) and excess antioxidant are removed.
Thus, EVOH (A) pellets containing the antioxidant (C) can be obtained, but usually, EVOH (A) pellets are obtained through a drying step after the above pelletization.

Although various drying methods can be adopted as such a drying method, it is preferable to perform fluidized drying, and it is particularly preferable to perform static drying after the fluidized drying. Will be described.

The fluidized drying referred to here is substantially the EVO.
The H (A) pellets means drying performed while being mechanically stirred or dispersed by hot air, and as a dryer for performing the drying, a cylinder / groove type stirring dryer, a cylindrical dryer, a rotary dryer, Examples thereof include a fluidized bed dryer, a vibrating fluidized bed dryer, a conical rotary dryer, and the stationary drying means that the EVOH (A) pellets are substantially given a dynamic action such as stirring and dispersion. Means a drying performed without any means, and as a dryer for performing the drying, a batch type box dryer is used as a material stationary type, and a band dryer, a tunnel dryer, or a vertical silo dryer is used as a material transfer type. However, the present invention is not limited to these.

Air or an inert gas (nitrogen gas, helium gas, argon gas, etc.) is used as the heating gas used in the fluidization drying process, and the temperature of the heating gas is preferably 95 ° C. or lower, and further, 40 to 90 ° C. is preferable, and if the temperature exceeds 95 ° C., EVOH (A) pellets are unfavorably fused. Further, the speed of the heating gas in the dryer is preferably 0.7 to 10 m / sec, more preferably 0.7 to 5 m / sec, and particularly preferably 1 to 3 m / sec, and such a speed is 0. 7 m
If it is less than 10 msec, fusion of EVOH (A) pellets tends to occur.
(A) Pellet chipping is likely to occur, which is not preferable. Also, the time for fluidized drying is EVOH
(A) Usually 5 minutes to 36, depending on the amount of pellets processed
Time is preferable, and further 10 minutes to 24 hours is preferable.

The EVOH (A) pellets are fluidized and dried under the above-mentioned conditions.
The water content of the (A) pellets is 5 to 60% by weight (further 1
0-55% by weight), and when the water content is less than 5% by weight, the EVO obtained after the static drying treatment is obtained.
When H (A) pellets are melt-molded, discharge fluctuations tend to occur, and conversely, when the H (A) pellets exceed 60% by weight, EVOH (A) pellets tend to melt during the subsequent stationary drying treatment, which is not preferable. Further, in such fluidized drying treatment, 5% by weight or more (further, 10 to 45% by weight) compared to before the treatment
It is preferable to lower the water content, and the decrease in water content is 5
Even in the case of less than wt%, EV is used during the subsequent (static) drying treatment.
OH (A) pellets are easily fused, which is not preferable.

EVOH fluidized and dried as described above
The (A) pellets are then subjected to a static drying treatment, and an inert gas (nitrogen gas, helium gas, argon gas, etc.) is also used as the heating gas used in the static drying treatment. The temperature of the heating gas is preferably 75 ° C or higher, more preferably 85 to 150 ° C, and the temperature is 75 ° C.
If it is less than 1, the drying time needs to be extremely long, which is economically disadvantageous, which is not preferable. Further, the gas velocity in the drier is preferably less than 1 m / sec, more preferably 0.01 to 0.5 m / sec, and if the velocity exceeds 1 m / sec, the EVOH (A) pellets will be removed. It is not preferable because it is difficult to keep it in a standing state.

Also, the time for static drying treatment is EVOH.
Although it cannot be generally stated depending on the treatment amount of (A) pellets, it is usually 10 minutes to 72 hours, and more preferably 1.0 to 48 hours.
Time is preferred. EVOH (A) pellets were statically dried under the above conditions, and finally dried EVOH
The (A) pellets are obtained, but the water content of the EVOH (A) pellets after the treatment (final) is 0.01 to 4
0 wt% (further 0.1 to 30 wt%, especially 0.1
˜20% by weight), and when the water content is less than 0.01% by weight, the long-run moldability of the obtained resin composition tends to decrease, and conversely 40% by weight.
If it exceeds the range, foaming tends to occur during subsequent melt kneading with the component (B), which is not preferable.

The water content of EVOH (A) (pellets) referred to here is measured and calculated by the following method. [Measurement Method of Moisture Content] (Water content) EVOH (A) was weighed by an electronic balance (W1: unit mg), put in a hot air oven type dryer maintained at 150 ° C., and dried for 5 hours, and then further. The weight after allowing to cool in a desiccator for 30 minutes was similarly weighed (W2: mg), and the following (1)
Calculate from the formula. Moisture content (%) = {(W1-W2) / W1} × 100 (1)

Thus, a mixture of EVOH (A) and antioxidant (C) is obtained, and then the polyamide resin (B) is melt-kneaded. The method of melt-kneading is, for example, the same as described above. Kneader ruder, extruder, mixing roll, Banbury mixer,
It can be carried out using a known kneading device such as a plastomill, but it is usually industrially preferable to use a single-screw or twin-screw extruder, and if necessary, a vent suction device, a gear pump device, a screen. It is also preferable to provide a device or the like. In particular, in order to remove water and by-products (pyrolysis low-molecular-weight substances, etc.), one or more vent holes are provided in the extruder to suck under reduced pressure, and to prevent oxygen from entering the extruder. For this purpose, by continuously supplying an inert gas such as nitrogen into the hopper, it is possible to obtain a resin composition of excellent quality in which thermal coloring and thermal deterioration are reduced.

There are no particular restrictions on the supply of (A + C) and (B) to the extruder. 1) Solid (A + C)
A method in which C) and (B) are collectively mixed and melt-kneaded,
2) Method of adding solid (B) to molten state (A + C) and melt kneading 3) Method of adding solid (A + C) to molten state (B) and melt kneading 4) A method of mixing (A + C) and (B) in a molten state and melting and kneading can be mentioned. Among them, the method of 1) is practical in terms of simplicity of the apparatus, cost of the blended product, and the like.

Thus, a resin composition containing EVOH (A), a polyamide resin (B) having a melting point of 160 ° C. or less, and an amide group-containing antioxidant (C) used in the multilayer pipe of the present invention can be obtained. However, in the present invention, by further containing an acid component or a metal salt thereof in such a resin composition, the color tone of the resin composition, thermal stability, appearance of the resulting multilayer pipe, interlayer adhesion, low temperature resistance Crackability, heat shrinkage followability, heat aging resistance, long-run moldability and the like are preferable in terms of improvement, and such acid components include acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, and other organic acids. And inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, boric acid and phosphoric acid, and examples of the metal salt include sodium salt, potassium salt, calcium salt, magnesium salt and zinc salt of the above acids. Alkali metal, alkaline earth metal, include metal salts such as transition metals, particularly acetic acid, phosphoric acid, boric acid or its alkali metal salts, alkaline earth metal salts are preferred from the viewpoint of excellent effect.

The content of the acetic acid is 5 to 1000 ppm (further 10 to 500 p) based on the resin composition.
pm, especially 20 to 300 ppm) is preferable, and if the content is less than 5 ppm, the effect may not be sufficiently obtained, and conversely, if it exceeds 1000 ppm, the appearance and long-run formability of the multilayer pipe obtained. May be reduced or odor may be observed, which is not preferable.

The content of such phosphoric acid is preferably 5 to 1000 ppm (more preferably 10 to 500 ppm, particularly 20 to 300 ppm) in terms of phosphate radical based on the resin composition, and the content is less than 5 ppm. In that case, the effect of inclusion may not be sufficiently obtained.
If it exceeds 0 ppm, the appearance and long-run formability of the obtained multilayer pipe may be deteriorated, which is not preferable.

The content of such boric acid is 10 to 10,000 ppm (more preferably 20 to 5,000 ppm, especially 50 to 2,000 ppb) in terms of boron based on the resin composition.
m), and the content is 10 ppm
If the content is less than the above range, the effect of inclusion may not be sufficiently obtained, and conversely if the content exceeds 10,000 ppm, the appearance of the obtained multilayer pipe may be deteriorated, which is not preferable.

The content of the metal salt is preferably 5 to 1000 ppm (more preferably 10 to 500 ppm, particularly 20 to 300 ppm) in terms of metal based on the resin composition, and the content is 5 ppm. If it is less than 1,000, the effect of inclusion may not be sufficiently obtained.
If it exceeds ppm, the appearance and heat aging resistance of the obtained multilayer pipe may be deteriorated, which is not preferable. When the resin composition contains two or more kinds of alkali metal and / or alkaline earth metal salts, the total amount thereof is preferably within the above range.

The method of incorporating the acid component and its metal salt into the resin composition (A) is not particularly limited, and E
It may be contained in VOH (A), in polyamide resin (B) in advance, or at the same time when EVOH (A), polyamide resin (B) and antioxidant (C) are blended. , EVOH (A), polyamide resin (B), and antioxidant (C) may be contained in the resin composition after blending, or these methods may be combined. In order to obtain the effect more remarkably, a method of preliminarily containing it in EVOH (A) is preferable in terms of excellent dispersibility of the acid component and its metal salt.

As a method of preliminarily containing EVOH (A), a) EVOH having a water content of 20 to 80% by weight
In addition to the method in which the porous precipitate of (A) is brought into contact with an aqueous solution of an acid component or its metal salt to contain the acid component or its metal salt and then dried, a) a uniform solution of EVOH (A) ( water/
(Alcohol solution, etc.) containing an acid component or a metal salt thereof, extruded into a coagulating liquid in a strand shape, and then cutting the obtained strand to form pellets, and further drying treatment, c) EVOH (A ) And an acid component or a metal salt thereof are collectively mixed, and then melt-kneaded with an extruder or the like, d) Alkali (sodium hydroxide, hydroxide) used in the saponification step during the production of EVOH (A). (Eg, potassium) and the like to neutralize the acid component such as acetic acid and adjust the amount of residual acid components such as acetic acid and by-produced alkali metal salts such as sodium acetate and potassium acetate by washing with water. be able to. In order to obtain the effect more remarkably, a) which has excellent dispersibility of the acid component and its metal salt,
The method a) or d) is preferable, and the method a) or d) described above is particularly preferable from the industrial viewpoint.

In the present invention, to the extent that the resin composition does not impair the object of the present invention, saturated aliphatic amides (eg stearic acid amides), unsaturated fatty acid amides (eg oleic acid amides), bis Fatty acid amide (eg, ethylene bis stearic acid amide, etc.), fatty acid metal salt (eg, calcium stearate, magnesium stearate, zinc stearate, etc.), low molecular weight polyolefin (eg, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight) Lubricants such as polypropylene), organic acids (eg acetic acid, propionic acid,
Stearic acid, etc.), inorganic acids (eg boric acid, phosphoric acid etc.), inorganic salts (eg hydrotalcite etc.), plasticizers (eg aliphatic polyhydric alcohols such as ethylene glycol, glycerin, hexanediol etc.), oxygen absorption Agents (eg reduced iron powder, potassium sulfite, ascorbic acid, hydroquinone, gallic acid, etc.), heat stabilizers, light stabilizers, amide group-free antioxidants, UV absorbers, colorants, antistatic agents, interfaces Activator, antibacterial agent, antiblocking agent, slip agent, filler (for example, inorganic filler), other resin (for example, polyolefin, melting point 16)
Polyamide, polyester, etc. exceeding 0 ° C.) may be blended.

The multi-layer pipe of the present invention comprises at least one layer of the above-mentioned resin composition layer, and as the resin used for the layers provided other than the resin composition layer, polyolefin resin, polyester Resin, polyamide resin, copolyamide, polystyrene resin, polyvinyl chloride resin, polyvinylidene chloride resin, acrylic resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene,
Examples thereof include chlorinated polypropylene, aromatic and aliphatic polyketones, aliphatic polyalcohols, and the like, and polyolefin resin is preferably used. Specific examples of the polyolefin resin include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and ethylene. -Vinyl acetate copolymer (EVA), ionomer, ethylene-propylene (block and random)
Copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (having 4 carbon atoms
.About.20 .alpha.-olefin) copolymers, homo- or copolymers of olefins such as polybutene, polypentene, etc., or those obtained by graft-modifying these homo- or copolymers of olefins with unsaturated carboxylic acids or their esters, and alkoxysilyl. Having a group (water-crosslinkable polyolefin),
And polyolefin resins in a broad sense such as blends and cross-linked products of these, cross-linked polyethylene, polybutene, polypropylene, among others, mechanical properties, low temperature crack resistance, heat shrinkage followability of the resulting multilayer pipe It is preferable because it is excellent in heat aging resistance and the like.

Typical cross-linking methods for such cross-linked polyethylene include water cross-linking method, radiation cross-linking method and peroxide cross-linking method.

In the water-crosslinking method, the polyethylene side of a (multilayer) pipe produced by using polyethylene having an alkoxysilyl group which causes a condensation reaction by hydrolysis is crosslinked by treating it with water, hot water, steam or the like. It is a thing. As a manufacturing method thereof, it is possible to make a pipe of polyethylene that has been cross-linked in advance and then laminate the resin composition, or to make a multilayer pipe using polyethylene that has not been cross-linked and then cross-link the polyethylene layer.

The radiation crosslinking method means electron beam, γ ray, β ray,
This is to crosslink by irradiating the polyethylene surface of the (multilayer) pipe with ionizing radiation such as X-rays. As a manufacturing method thereof, it is possible to make a pipe of polyethylene that has been cross-linked in advance and then laminate the resin composition, or to make a multilayer pipe using polyethylene that has not been cross-linked and then cross-link the polyethylene layer.

The peroxide crosslinking method is a method in which a peroxide is reacted with polyethylene in an extruder to crosslink, and as the peroxide to be used, there are ketone peroxide, diacyl peroxide and hydroperoxide. Examples thereof include oxides, dialkyl peroxides and alkyl peresters. As a manufacturing method thereof, a resin pipe can be laminated after forming a pipe of cross-linked polyethylene in advance, or a cross-linked polyethylene and a resin composition can be simultaneously laminated by a coextrusion method.

The method for laminating each resin layer of the multi-layer pipe of the present invention is not limited. For example, a method of co-extruding each resin, a single-layer pipe of a resin composition is prepared in advance, and another resin is added thereto. Method of melt extrusion coating, method of previously forming a single-layer (or multi-layer) pipe of resin used for layers other than the resin composition, and method of melt extrusion coating the resin composition thereon, single layer of resin composition beforehand A method in which a pipe is prepared, and a molded product made of another resin is dry-laminated with a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound on the pipe, other than the resin composition in advance. A single-layer (or multi-layer) pipe made of resin used for the layer is prepared in advance,
A molded product made of the resin composition is added to the organic titanium compound,
Examples thereof include a method of dry laminating using a known adhesive such as an isocyanate compound, a polyester compound, and a polyurethane compound. The molding temperature during melt molding is
It is often selected from the range of 150 to 300 ° C.

The layer structure of the multi-layer pipe is as follows:
(A1, a2, ...) And another thermoplastic resin layer is b (b
1, b2, ...), not only the two-layer structure of a / b, but also b / a / b, a / b / a, a1 / a2 / b, a
/ B1 / b2, b2 / b1 / a / b1 / b2, b2 / b
Any combination such as 1 / a / b1 / a / b1 / b2 is possible, and when R is a regrind layer composed of at least a mixture of a resin composition and another thermoplastic resin, b / R / a, b / R / a / b, b / R / a / R /
b, b / a / R / a / b, b / R / a / R / a / R / b
Etc. are also possible.

In the above layer structure, an adhesive resin layer may be provided between the respective layers, if necessary, and various kinds of adhesive resin may be used to improve the appearance. It is preferable in that a multi-layer pipe having excellent delamination resistance, low temperature crack resistance, heat shrinkage followability, heat aging resistance, etc. can be obtained, and it depends on the molding method and application of the multi-layer pipe. A modified olefin polymer containing a carboxyl group obtained by chemically bonding an acid or an anhydride thereof to an olefin polymer (a homopolymer or a copolymer of the above-mentioned olefins) by an addition reaction or a graft reaction, etc. As the unsaturated carboxylic acid or its anhydride, maleic acid, maleic anhydride, fumaric acid, acrylic acid, methacrylic acid, crotonic acid, itaconic acid can be used. Examples thereof include citraconic acid and hexahydrophthalic anhydride. Among them, maleic anhydride is preferably used, and specifically, maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-propylene. One or a mixture of two or more selected from (block or random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer and the like is preferable. It is mentioned as a thing.

At this time, the amount of unsaturated carboxylic acid or its anhydride contained in the modified resin is 0.001 to
It is preferably 3% by weight, more preferably 0.01 to 1% by weight, particularly preferably 0.03 to 0.5% by weight.
If the amount of modification in the modified product is small, the adhesiveness may be insufficient, and conversely, if it is large, a cross-linking reaction may occur, resulting in poor moldability, which is not preferable. It is also possible to blend these adhesive resins with a resin composition, other rubber / elastomer components such as EVOH, polyisobutylene, ethylene-propylene rubber, and other thermoplastic resins. In particular, blending a polyolefin resin different from the base polyolefin resin of the adhesive resin is useful because the adhesiveness may be improved.

The most preferable layer structure of the multilayer pipe of the present invention is [inside] polyolefin resin layer / adhesive resin layer / resin composition layer [outside] and [inside] polyolefin resin layer / adhesive resin layer. / Resin composition layer / adhesive resin layer / polyolefin resin layer [outside].
[Inside] A multi-layer pipe having a layer structure of polyolefin resin layer / adhesive resin layer / resin composition layer [outside] has a coextrusion method or an extrusion coating method (adhesion on a pipe made of a preformed polyolefin resin). The resin and the resin composition can be suitably produced in production by coextrusion coating or sequential extrusion coating). [Inside] Polyolefin resin layer / Adhesive resin layer / Resin composition layer / Adhesive resin layer / Polyolefin resin layer [Outside]
The multi-layer pipe having the above-mentioned layer constitution can be generally produced favorably in production by the coextrusion method.

The thickness of each layer of the multi-layer pipe cannot be generally determined depending on the layer constitution, application, required physical properties, etc., but usually the layer a is 20 to 1000 μm (further 50 to 500 μm).
μm), and the layer b is 100 to 10000 μm (more 20
0-5000 μm), the adhesive resin layer is 10-1000 μm
It is selected from the range of about m (further, 30 to 300 μm). If the layer a is less than 20 μm, the gas barrier properties of the resulting multi-layer pipe are deteriorated, and its thickness control becomes unstable. Conversely, if it exceeds 1000 μm, the low-temperature crack resistance of the multi-layer pipe obtained is inferior and it is not economical. If the layer b is less than 100 μm, the rigidity of the obtained multilayer pipe is insufficient, and conversely, if it exceeds 10,000 μm, the flexibility of the obtained multilayer pipe is lowered, and the weight becomes unnecessarily large, and it is not economical. If the thickness of the adhesive resin layer is less than 10 μm, the interlayer adhesion of the obtained multilayer pipe is insufficient, and the thickness control becomes unstable,
On the contrary, if it exceeds 1000 μm, the weight becomes unnecessarily large, and it is not economical and not preferable.

Further, in each layer of the multi-layer pipe of the present invention, the above-mentioned various additives, modifiers, fillers, other resins, etc. are added to the effect of the present invention in order to improve molding processability and various physical properties. It is also possible to add in a range that does not.

The multilayer pipe of the present invention thus obtained is
Excellent in gas barrier property, low temperature crack resistance, heat shrinkage followability, heat aging resistance, long run formability, supply / circulation / discharge of cold water, hot water or hot water, fuel transportation, ink transportation, solvent transportation, etc. Useful as a pipe for liquids and gases in
It can be used in a wide range of applications, and is particularly preferably used as a pipe for circulating hot water or hot water in floor heating, central heating and the like.

[0066]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "part" and "%" mean weight basis unless otherwise specified.

For the measurement of the melting point and the heat of fusion (ΔH) of the polyamide resin (B), a differential scanning calorimeter (PERK) is used.
It was carried out by measuring at a temperature rising rate of 10 ° C./min using “Pyris1” manufactured by IN ELMER. Further, the content of boric acid in the EVOH (A) and the resin composition was measured by melting the EVOH (A) and the resin composition with an alkali and quantifying boron by ICP emission spectroscopy. Furthermore, alkali (earth)
The metal content was measured by ashing the EVOH (A) and the resin composition, dissolving the EVOH (A) in a hydrochloric acid aqueous solution, and quantifying the alkali (earth) metal by atomic absorption spectrometry.

Example 1 EVOH [ethylene content 35 mol%, saponification degree 99.
5 mol%, MFR 12 g / 10 minutes (210 ° C., load 21
60 g)] (A) water / methanol (water / methanol =
40/60 mixing weight ratio) mixed solution (EVOH concentration 45
%) 100 parts by weight of a hindered phenolic antioxidant [N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxyphenylethylamide), manufactured by Ciba Specialty Chemicals "IRGANOX 109".
8 ″] (C) Add 2.5 parts of 8% dispersion and add 3 at 40 ° C.
Mixing and stirring for 0 minutes, and EVOH containing antioxidant (C)
A solution (containing 0.45 parts of antioxidant (C) per 100 parts of EVOH (A)) was obtained. Then, the solution is heated to 5 ° C.
After being extruded into a coagulating liquid (mixed liquid of water / methanol = 95/5 (weight ratio)) tank maintained at 10 cm from a cylindrical nozzle having an inner diameter of 0.4 cm and a length of 6.0 cm in a strand shape to coagulate, Porous EVOH pellets cut with a cutter (pellet shape: diameter 5 mm, length 5 mm, water content 5
0%). The EVOH pellets obtained are heated to a temperature of 30 ° C.
After washing with water in a water bath of No. 3, it was poured into an aqueous solution containing 0.3% boric acid and 0.1% sodium acetate, stirred at 35 ° C. for about 4 hours, and further dried by the following method. It was

<Fluid Drying Step> EVOH obtained above
The pellets were collected using a batch type fluidized bed dryer (tower type) at 75
Drying was carried out for about 3 hours while flowing nitrogen gas at ℃ to obtain EVOH pellets having a water content of 20%. The water content of the EVOH pellets before fluidized drying was 50%, and the water content difference between the EVOH pellets before and after fluidized drying was 30%.

<Stand-drying process> Next, the EVOH pellets after the fluidized-drying treatment were dried with a nitrogen gas at 125 ° C. for about 9 hours using a batch box dryer (aeration type) to obtain a water content of 5%. .5% EVOH composition pellets [EVOH
Antioxidant (C) was added to 100 parts by weight of (A) in an amount of 0.
45 parts, 0.03 parts of boric acid in terms of boron and 0.012 parts of sodium acetate in terms of sodium content were obtained.

Next, the EVOH composition (A + C) 90
Part and polyamide-based resin ["Grillon CF6S" manufactured by EMS Japan, nylon 6/12 copolymer, density 1.0
5 g / cm ³ , melting point 133 ° C., ΔH51 J / g, MFR
18g / 10 minutes (210 ° C, load 2160g)] (B)
10 parts of the resin composition was melt-kneaded in a twin-screw extruder under the following conditions to obtain a resin composition [water content: 0.15%, antioxidant (C): EVO].
0.4 parts, boric acid of 270 ppm in terms of boron and sodium acetate of 110 ppm in terms of sodium were contained per 100 parts of the total amount of H (A) and polyamide resin (B).

[0072] [Conditions for melt pelletization with a twin-screw extruder]   Screw inner diameter 30mm (L / D = 30)   Screw shape With a 100 mm kneading disk in the compression section   Screen mesh 90/90 mesh   Screw rotation speed 150 rpm   Vent hole Perform vacuum suction   Supply nitrogen gas in hopper to replace   Extrusion temperature C1: 120 ° C                         C2: 170 ° C                         C3: 210 ° C                         C4: 220 ° C                         C5: 220 ° C                         AD: 210 ° C                         D: 210 ° C

The resin composition obtained above was supplied to a multi-layer pipe extrusion molding apparatus equipped with a multi-layer die having three layers of three feedblocks, and (inside) water-crosslinkable polyethylene (“LINKLON HF835N” manufactured by Mitsubishi Chemical Corporation). )) Layer / adhesive resin (“Admer NF468E” manufactured by Mitsui Chemicals, Inc.) layer / resin composition layer (outer side) layer structure (thickness 1750/100/15)
0 μm) multi-layer pipe (outer diameter 22 mm, inner diameter 18 mm)
Got Next, hot water (temperature: 95 ° C., pressure: 12 kg / cm ² ) was circulated inside the obtained multi-layer pipe for 12 hours to water-crosslink the inner cross-linked polyethylene layer to obtain the multi-layer pipe of the present invention.

The gas barrier properties, low temperature crack resistance, heat shrinkage followability, heat aging resistance, and long run moldability of the obtained multi-layer pipe were evaluated as follows.

(Gas Barrier Property) One end of the obtained multi-layer pipe (length 5 m) was sealed with an aluminum plate and a mixed epoxy adhesive, and the other end was oxygen permeation measuring device (MOC).
ON company "OXTRAN10 / 50"), temperature 40 ℃, outside humidity 50% RH, inside humidity 100% RH
The oxygen permeability was measured under the conditions of.

(Low temperature crack resistance) The end portion of the obtained multi-layer pipe was adjusted to an inner diameter of 30 with an expansion jig at a temperature of -20 ° C.
The EVOH layer of the outer layer was expanded to a size of mm, and the presence or absence of cracks in the outer EVOH layer was visually observed and evaluated according to the following criteria. ◯: No cracks were found Δ: Width 10 to 20 μm, length 10 on the EVOH layer surface
Some micro cracks of 0 to 300 μm are observed,
No large cracks are observed ..... Width 10-20 .mu.m, length 10 on EVOH layer surface.
A large number of microcracks of 0 to 300 μm and a width of 30 to 6
Dozens of large cracks with a length of 0 μm and a length of 1 cm are recognized.

(Heat shrinkage conformability) The obtained multi-layer pipe was cut into a length of 500 mm, and the multi-layer pipe was installed in an L-shape in a thermostat with a fixing jig so that it could be bent into an L-shape.
The temperature was repeatedly changed at 16 cycles / day between 5 ° C. and 95 ° C., and the number of cycles until cracks were completely generated in the bent portion was measured and evaluated according to the following criteria. ○ ・ ・ ・> 5000 cycles △ ・ ・ ・ 2000-5000 cycles × ・ ・ ・ <2000 cycles

(Heat-resistant aging resistance) Using the resin composition used for the above-mentioned multi-layer pipe, another single-layer film forming apparatus was used to obtain a thickness of 100.
A μm monolayer film was obtained. Then, a strip-shaped test piece having a length of 50 mm and a width of 15 mm is cut out, and the test piece is left in a hot air oven at 140 ° C. for 200 hours to be heat-treated, and then pulled in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH. A test (pulling speed 50 mm / min) was performed. From the obtained value of the breaking elongation and the value of the breaking elongation of the test piece which was not heat-treated, the retention rate of the breaking elongation (ratio of the breaking elongation before and after the heat treatment) was calculated and evaluated.

(Long-run moldability) The above-mentioned multilayer pipe was continuously molded for 24 hours, and the occurrence frequency of eye-like foreign matter accumulated in the die lip and the occurrence frequency of gel-like foreign matter confirmed in the EVOH layer were visually observed. And evaluated according to the following criteria. ◯: Generation of eye-like foreign matter was slight even after 24 hours from the start of molding, and almost no gel-like foreign matter was observed. △: Occurrence of eye-like foreign matter was observed from the start of molding.
The occurrence of gel-like foreign matter is frequently observed 12 hours after the start of molding .... A large amount of eye-like foreign matter is observed after the start of molding, and the gel-like foreign matter is frequently generated 6 hours after the start of molding. Recognized by

Example 2 In Example 1, using a multi-layer pipe extrusion molding apparatus equipped with a multi-layer die having three layers of five kinds of feed blocks, [inside] polybutene (manufactured by Mitsui Chemicals, Inc. “Buron”) layer / adhesive resin (Mitsui Chemicals'"AdmerAT843E") layer / resin composition layer / adhesive resin (same as left) layer / polybutene (same as left) layer [outside] layer structure (thickness 850/75/15
0/75/850 μm multi-layer pipe (outer diameter 22 mm,
An inner diameter of 18 mm) was obtained and evaluated in the same manner.

Example 3 In Example 1, the thickness of the multilayer pipe was changed to [inside].
Water-crosslinkable polyethylene layer / adhesive resin layer / resin composition layer [outside] = 1800/80/120 μm (outer diameter 28 m
m, inner diameter 24 mm), and the same evaluation was performed. However, in the low temperature crack resistance test, the obtained multilayer pipe was expanded and evaluated until the inner diameter was 40 mm.

Example 4 In Example 1, the ethylene content was 32 mol%, the saponification degree was 99.6 mol%, the MFR was 15 g / 10 min (210 ° C.,
Load 2160g)] EVOH (A) is used and EV
EVOH composition containing 0.67 part of antioxidant (C), 0.02 part of boric acid in terms of boron and 0.004 part of magnesium acetate in terms of magnesium with respect to 100 parts by weight of OH (A). Except that the resin composition was prepared in the same manner as above [water content 0.13%, antioxidant (C) added to EVO
0.6 parts per 100 parts of the total amount of H (A) and polyamide resin (B), 180 ppm of boric acid in terms of boron and 36 ppm of magnesium acetate in terms of magnesium
Content] was obtained, and a multilayer pipe was similarly obtained, and evaluated in the same manner.

Example 5 In Example 1, ethylene content was 38 mol%, saponification degree was 99.5 mol%, MFR 25 g / 10 min (210 ° C.,
Load 2160g)] EVOH (A) is used and EV
EVOH composition containing 0.35 parts of antioxidant (C), 0.04 parts of boric acid in terms of boron and 0.008 parts of calcium acetate in terms of calcium based on 100 parts by weight of OH (A). Except that the resin composition was prepared in the same manner as above [moisture content: 0.17%, antioxidant (C): EVOH
0.32 parts per 100 parts of the total amount of (A) and the polyamide-based resin (B), 360 ppm of boric acid in terms of boron and 72 ppm of calcium acetate in terms of calcium are obtained] to obtain a multilayer pipe in the same manner. And evaluated in the same manner.

Example 6 In Example 1, as the polyamide resin (B), "Amilan CM8000" manufactured by Toray Industries, Inc. [nylon 6/66 /
610/12 copolymer, density 1.12 g / cm ³ , melting point 131 ° C., ΔH 40 J / g, MFR 25 g / 10 min (210 ° C., load 2160 g)] were obtained in the same manner as above, A multilayer pipe was prepared in the same manner and evaluated in the same manner.

Example 7 In Example 2, as the polyamide-based resin (B), "Grillon CA6E" manufactured by EMS Japan Co. [nylon 6 /
12 copolymer, density 1.06 g / cm ³ , melting point 124
° C, ΔH39J / g, MFR 26g / 10min (210
C., load 2160 g)] was obtained in the same manner as above except that a multi-layer pipe was prepared and evaluated in the same manner.

Example 8 In Example 3, as the polyamide resin (B), "Amilan CM6541-X3" manufactured by Toray Industries, Inc. [nylon 6 /
12 copolymer, density 1.11 g / cm ³ , melting point 135
° C, ΔH40J / g, MFR 12g / 10min (210
C., load 2160 g)] was obtained in the same manner as above except that a multi-layer pipe was prepared and evaluated in the same manner.

Example 9 In Example 1, the blending ratio of the EVOH composition (A + C) and the polyamide resin (B) was EVOH (A) 85.
Resin composition (water content 0.15%, antioxidant (C))
The total amount of EVOH (A) and polyamide resin (B) 1
0.38 parts to 00 parts, 25 boric acid in terms of boron
0 ppm and 10% sodium acetate in terms of sodium
0ppm content] was obtained, and a multi-layer pipe was similarly prepared,
It evaluated similarly.

Example 10 In Example 3, the blending ratio of the EVOH composition (A + C) and the polyamide resin (B) was EVOH (A) 80.
Resin composition (moisture content 0.15%, antioxidant (C))
The total amount of EVOH (A) and polyamide resin (B) 1
0.36 parts with respect to 00 parts, boric acid 24 in terms of boron
0 ppm and 95% sodium acetate converted to sodium
[ppm content] was obtained, a multilayer pipe was produced in the same manner, and the same evaluation was performed.

Example 11 In Example 4, the blending ratio of the EVOH composition (A + C) and the polyamide resin (B) was EVOH (A) 75.
Resin composition (moisture content 0.13%, antioxidant (C))
The total amount of EVOH (A) and polyamide resin (B) 1
0.5 part for 100 parts, 150 boric acid in terms of boron
ppm and magnesium acetate in terms of magnesium 3
0ppm content] was obtained, and a multi-layer pipe was similarly prepared,
It evaluated similarly.

Comparative Example 1 A resin composition was obtained in the same manner as in Example 1 except that the polyamide resin (B) was not contained in the resin composition, and a multilayer pipe was produced in the same manner. went.

Comparative Example 2 In Example 1, as the polyamide resin (B), "Amilan CM6541-X4" (nylon 6 /
12 copolymer, density 1.10 g / cm ³ , melting point 196
(° C) was used to obtain a resin composition in the same manner, a multilayer pipe was produced in the same manner, and the same evaluation was performed.

Comparative Example 3 A resin composition was obtained in the same manner as in Example 1 except that the antioxidant (C) was not contained in the resin composition, and a multilayer pipe was produced in the same manner. went.

Comparative Example 4 In Example 1, as the antioxidant (C), the hindered phenolic antioxidant [pentaerythrityl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) was used. ) Propionate), "Irganox 1010" manufactured by Ciba Specialty Chemicals Co., Ltd.] was used to obtain a resin composition in the same manner, a multilayer pipe was produced in the same manner, and the same evaluation was performed.

Table 1 shows the evaluation results of the examples and comparative examples. [Table 1] Gas barrier Resistance to low-temperature heat shrinkage Heat-resistant aging Long-run property 1) Crackability Followability Formability Example 1 0.038 ○ ○ 0.60 ○ 〃 2 0.046 ○ ○ 0.60 ○ 〃 3 0.049 ○ ○ 0.60 ○ 〃 4 0.035 ○ ○ 0.58 ○ 〃 5 0.050 ○ ○ 0.65 ○ 〃 6 0.040 ○ ○ 0.61 ○ 〃 7 0.039 ○ ○ 0.62 ○ 〃 8 0.039 ○ ○ 0.61 ○ 〃 9 0.040 ○ ○ 0.57 ○ 〃 10 0.055 ○ ○ 0.54 ○ 〃 11 0.042 ○ ○ 0.52 ○ Comparative Example 1 0.034 × × 0.62 ○ 〃 2 0.037 × × 0.55 × 〃 3 0.038 ○ ○ 0.05 ○ 〃 4 0.038 △ △ 0.18 △ 1) Unit: cc / day air

[0095]

INDUSTRIAL APPLICABILITY The multilayer pipe of the present invention is EVOH (A)
Since it contains at least one resin composition layer comprising a specific polyamide resin (B) and a specific antioxidant (C), gas barrier properties, low temperature crack resistance, heat shrinkage followability, heat aging resistance, It has excellent long-run formability and is useful as a pipe for various liquids and gases such as supply / circulation / discharge of cold water, hot water or hot water, fuel transportation, ink transportation, solvent transportation, etc., and it is used in a wide range of applications. It is possible to use it, and it is particularly preferable to use it for hot water or hot water circulation pipe applications in floor heating, central heating and the like.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 5/55 C08K 5/55 C08L 23/26 C08L 23/26 29/04 29/04 D 77/00 77 / 00 F16L 9/14 F16L 9/14 F-term (reference) 3H111 AA02 BA15 BA31 BA34 CA53 CB02 CB04 CB06 DA26 DB03 EA04 4F100 AH02 AH02H AH03A AH03H AK03B AK03C AK04B AK04C AK07B AK07C AK09B AK09C AK46A AK69A AL05A AT00B AT00C AT00D AT00E BA02 BA03 BA04 BA05 BA06 BA07 BA10A BA10B BA10C BA10D BA10E CA06 DA11 EH20 EH202 EJ05 EJ053 EJ42 EJ423 GB08 GB90 JA04A JD02 JK01 JK10 YY00A 4J002 BB22W BE03W CL00X EU00 GD076 EW076 007

Claims (9)

[Claims] 1. A saponified ethylene-vinyl acetate copolymer (A), a polyamide resin (B) having a melting point of 160 ° C. or lower.
A multilayer pipe comprising at least one layer of a resin composition containing the amide group-containing antioxidant (C). 2. The content weight ratio (A / B) of the saponified product of ethylene-vinyl acetate copolymer (A) and the polyamide resin (B) having a melting point of 160 ° C. or less is 50/50 to 99/1.
The multi-layer pipe according to claim 1, wherein 3. The total content of the amide group-containing antioxidant (C) is 1 in total of saponified ethylene-vinyl acetate copolymer (A) and polyamide resin (B) having a melting point of 160 ° C. or lower.
The multilayer pipe according to claim 1 or 2, wherein the amount is 0.01 to 3 parts by weight with respect to 00 parts by weight. 4. The multilayer pipe according to claim 1, wherein the content of the boron compound in the resin composition is 10 to 10,000 ppm in terms of boron. 5. The heat of fusion (ΔH) of the polyamide resin (B) having a melting point of 160 ° C. or less measured by a differential scanning calorimeter (DSC) (heating rate 10 ° C./min) is 8.
It is 0 J / g or less, The multilayer pipe in any one of Claims 1-4 characterized by the above-mentioned. 6. The multilayer pipe according to claim 1, having a layer structure of [inside] polyolefin resin layer / adhesive resin layer / resin composition layer [outside]. 7. A layer structure of [inside] polyolefin resin layer / adhesive resin layer / resin composition layer / adhesive resin layer / polyolefin resin layer [outside]. Either of the multilayer pipes. 8. The multilayer pipe according to claim 6, wherein the polyolefin resin is at least one selected from cross-linked polyethylene, polybutene, and polypropylene. 9. The multi-layer pipe according to claim 1, which is used as a pipe for circulating hot water.