JP2014201044A - Multilayer structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer structure excellent in flexibility and fuel barrier property.SOLUTION: There is provided a multilayer structure having a polyolefin layer (A) and a polyether-polyamide layer (B), wherein the polyether-polyamide (B) contains a polyether-polyamide (b) containing a constitutional unit in which a diamine constitutional unit is derived from a polyether diamine compound (b-1) represented by the following general formula (1) and a xylylene diamine (b-1) and a constitutional unit in which a dicarboxylic acid constitutional unit is derived from an α,ω-straight-chain aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms. (wherein, x+z represents 1 to 60; y represents 1 to 50; -OR- each independently represents -OCHCHCH-, -OCH(CH)CH- or -OCHCH(CH)-; and -OR- represents -OCHCHCHCH- or -OCHCH-.)

Description

  The present invention relates to a multilayer structure excellent in flexibility and fuel barrier properties.

Conventionally, tubular molded bodies such as polyolefin hoses, tubes and pipes have been used in a wide range of applications due to their high chemical resistance, for example, used as water pipes for supplying tap water to each house. Has been.
When supplying tap water to each house, water pipes are buried in the ground from the water main to each house. Among polyolefins, polyethylene tubular moldings are lightweight and excellent in flexibility, and are suitable for transporting to the site where they are wound around a core and buried in water pipes. Is widely used.

On the other hand, fuel pipes such as kerosene pipes are also buried in the ground, and these fuel pipes are mainly made of copper, and fuel leaks slightly into the soil due to deterioration of the fuel pipes. is there. Therefore, when fuel pipes are buried in the vicinity of water pipes buried underground, the fuel leaked from the fuel pipes penetrates into the water in the polyethylene pipes, resulting in a problem that the fuel odor is given to the tap water. Yes.
In order to solve the above problem, for example, in Patent Document 1, a metal laminate film in which a resin layer and a metal layer are laminated is used as a water pipe protective cover, and a water pipe buried in the ground is used as the water pipe protective cover. A coating method has been proposed.

Japanese Patent No. 42306060

  However, in the above method, since it is necessary to further process the protective cover to the once formed pipe, the productivity of the water pipe is inferior, the work becomes complicated, and it is difficult to say that it is practical. Therefore, the fuel barrier property of water supply piping alone is calculated | required, without requiring a protective cover etc.

  Then, this invention makes it a subject to provide the multilayer structure excellent in the softness | flexibility and fuel-barrier property which can be applied to water piping, while having the outstanding softness | flexibility made from polyolefin.

The present inventors have found that the above problems can be solved by forming a multilayer structure having a polyolefin layer and a specific polyether polyamide layer, and have reached the present invention.
That is, the present invention relates to the following multilayer structure.

<1> A multilayer structure having a polyolefin layer (A) and a polyether polyamide layer (B), wherein the polyether polyamide layer (B) has a diamine structural unit represented by the following general formula (1): An α, ω-linear aliphatic dicarboxylic acid (b-3) containing a structural unit derived from the etherdiamine compound (b-1) and xylylenediamine (b-2) and having a dicarboxylic acid structural unit of 4 to 20 carbon atoms The multilayer structure containing the polyether polyamide (b) containing the structural unit derived from.

(In the formula, x + z represents 1 to 60, y represents 1 to 50, and —OR ¹ — represents each independently —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH ( CH ₃ ) — and —OR ² — represents —OCH ₂ CH ₂ CH ₂ CH ₂ — or —OCH ₂ CH ₂ —.

<2> The multilayer structure described above, wherein the multilayer structure is a cylindrical molded body.
<3> The multilayer structure as described above, which is a water pipe.

  The present invention can provide a multilayer structure excellent in flexibility and fuel barrier properties while having the excellent flexibility of a tubular molded body made of polyolefin, and further, a water pipe having the above characteristics of the multilayer structure Can be provided.

The multilayer structure of the present invention has at least a polyolefin layer (A) and a polyether polyamide layer (B) as constituent layers, and examples of specific embodiments will be described below.
In the present specification, the term “main component” is intended to allow other components to be included within a range that does not impede the effects of the multilayer structure of the present invention. It is a component that occupies a range of about 80% by mass or more, preferably 90% by mass or more and 100% by mass or less of the total components. However, “main component” does not specify the above content.

[Polyolefin layer (A)]
The polyolefin layer (A) is a layer containing a polyolefin resin as a main component. As the polyolefin resin, for example, polyethylene, polypropylene or the like can be used, and it may be a homopolymer or a copolymer. Among the polyolefin resins, polyethylene is preferable from the viewpoint of flexibility, weather resistance, and chlorine resistance.
As the polyethylene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and the like can be used.

As the copolymer, a copolymer of ethylene or propylene and a monomer that can be copolymerized with these can be used. As a monomer that can be copolymerized with ethylene or propylene, Examples thereof include α-olefins, styrenes, dienes, cyclic compounds, oxygen atom-containing compounds, and the like.
Examples of the α-olefin include 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-pentene, 1-hexene, 1-heptene and 1-octene. 1-decene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like. Examples of the styrenes include styrene, 4-methylstyrene, 4-dimethylaminostyrene and the like. Examples of the dienes include 1,4-butadiene, 1,5-hexadiene, 1,4-hexadiene, 1,7-octadiene, and the like. Examples of the cyclic compound include norbornene and cyclopentene. Examples of the oxygen atom-containing compound include hexenol, hexenoic acid, and methyl octenoate. These monomers that can be copolymerized may be used alone or in combination of two or more. Further, it may be a copolymer of ethylene and propylene.
The copolymer may be any of alternating copolymerization, random copolymerization, and block copolymerization.

  The polyolefin resin may contain a small amount of a modified polyolefin resin modified with a carboxyl group-containing monomer such as acrylic acid, maleic acid, methacrylic acid, maleic anhydride, fumaric acid, and itaconic acid. The modification is usually performed by copolymerization or graft modification.

[Polyether polyamide layer (B)]
The polyether polyamide layer (B) is a layer containing the polyether polyamide (b) as a main component. The polyether polyamide (b) includes a structural unit derived from a polyetherdiamine compound (b-1) and xylylenediamine (b-2) whose diamine structural unit is represented by the following general formula (1), and is a dicarboxylic acid A polyether polyamide containing a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms.
By including the polyether polyamide layer (B), the multilayer structure of the present invention can exhibit excellent fuel barrier properties without impairing the flexibility of the polyolefin layer.

In the formula, x + z represents 1 to 60, y represents 1 to 50, and —OR ¹ — represents each independently —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃₎ - represents, -OR ² - is _{-OCH 2 CH 2 CH 2 CH 2} - represents a - or -OCH ₂ CH _2.

(Diamine structural unit)
The diamine structural unit constituting the polyether polyamide (b) includes a structural unit derived from the polyetherdiamine compound (b-1) and xylylenediamine (b-2) represented by the general formula (1).
The total content of the structural units derived from the polyetherdiamine compound (b-1) and xylylenediamine (b-2) in the diamine structural unit is preferably 50 to 100 mol%, more preferably 70 to 100. It is mol%, More preferably, it is 80-100 mol%, More preferably, it is 90-100 mol%.

<Polyetherdiamine compound (b-1)>
The diamine structural unit constituting the polyether polyamide (b) includes a structural unit derived from the polyether diamine compound (b-1) represented by the general formula (1). In the general formula (1), (x + z) is 1 to 60, preferably 2 to 40, more preferably 2 to 30, still more preferably 2 to 20, and still more preferably 2 to 15. Moreover, y is 1-50, Preferably it is 1-40, More preferably, it is 1-30, More preferably, it is 1-20. When the values of x, y, and z are larger than the above ranges, the compatibility of the oligomer or polymer composed of xylylenediamine and dicarboxylic acid generated during the reaction of the melt polymerization is lowered, and the polymerization reaction is difficult to proceed.
In the general formula (1), —OR ¹ — represents independently —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃ ) —, and —OR ² — represents —OCH ₂ CH ₂ CH ₂ CH ₂ — or —OCH ₂ CH ₂ —.

  The number average molecular weight of the polyetherdiamine compound (b-1) is preferably 180 to 5700, more preferably 200 to 4000, still more preferably 300 to 3000, still more preferably 400 to 2000, and still more preferably 500 to 1800. It is. When the number average molecular weight of the polyetherdiamine compound is within the above range, a polymer that exhibits functions such as flexibility and rubber elasticity can be obtained.

  The polyether diamine compound (b-1) represented by the general formula (1) is preferably a polyether diamine compound represented by the following general formula (1-1) or (1-2).

In general formula (1-1), x1 + z1 represents 1 to 60, y1 represents 1 to 50, and —OR ¹ — represents —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH _2. CH (CH ₃ ) — is represented.
In general formula (1-2), x2 + z2 represents 1 to 60, y2 represents 1 to 50, and —OR ¹ — represents —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH _2. CH (CH ₃ ) — is represented.

The numerical value of (x1 + z1) in the general formula (1-1) is 1 to 60, preferably 2 to 40, more preferably 2 to 30, still more preferably 2 to 20, and still more preferably 2 to 15. It is. Moreover, the numerical value of y1 is 1-50, Preferably it is 1-40, More preferably, it is 1-30, More preferably, it is 1-20.
The numerical value of (x2 + z2) in the general formula (1-2) is 1-60, preferably 2-40, more preferably 2-30, still more preferably 2-20, and even more preferably 2-15. It is. Moreover, the numerical value of y2 is 1-50, Preferably it is 1-40, More preferably, it is 1-30, More preferably, it is 1-20.
In addition, you may use these polyetherdiamine compounds (b-1) individually or in combination of 2 or more types.

The number average molecular weight of the polyetherdiamine compound represented by the general formula (1-1) is preferably 204 to 7000, more preferably 250 to 5000, still more preferably 300 to 3500, still more preferably 400 to 2500, More preferably, it is 500-1800.
The number average molecular weight of the polyetherdiamine compound represented by the general formula (1-2) is preferably 180 to 5700, more preferably 200 to 4000, still more preferably 300 to 3000, and still more preferably 400 to 2000, More preferably, it is 500-1800.

<Xylylenediamine (b-2)>
The diamine structural unit constituting the polyether polyamide (b) includes a structural unit derived from xylylenediamine (b-2). The xylylenediamine (b-2) is preferably metaxylylenediamine, paraxylylenediamine or a mixture thereof, more preferably metaxylylenediamine or a mixture of metaxylylenediamine and paraxylylenediamine, More preferred is a mixture of xylylenediamine and paraxylylenediamine.
When xylylenediamine (b-2) is derived from metaxylylenediamine, the resulting polyether polyamide is excellent in flexibility, crystallinity, melt moldability, moldability, and toughness.
When xylylenediamine (b-2) is derived from a mixture of metaxylylenediamine and paraxylylenediamine, the resulting polyether polyamide has flexibility, crystallinity, melt moldability, molding processability, and toughness. Excellent, high heat resistance and high elastic modulus.

  When a mixture of metaxylylenediamine and paraxylylenediamine is used as xylylenediamine (b-2), the ratio of paraxylylenediamine to the total amount of metaxylylenediamine and paraxylylenediamine is preferably It is 90 mol% or less, More preferably, it is 80 mol% or less, More preferably, it is 5-70 mol%. If the ratio of paraxylylenediamine is within the above range, the melting point of the obtained polyether polyamide is preferable because it is not close to the decomposition temperature of the polyether polyamide.

  The proportion of the structural unit derived from the polyetherdiamine compound (b-1) in the diamine structural unit of the polyether polyamide (b) is preferably 5 to 50 mol%, more preferably 5 to 30 mol%, still more preferably. 5 to 25 mol%. If the proportion of the structural unit derived from the polyetherdiamine compound (b-1) in the diamine structural unit of the polyether polyamide (b) is within the above range, the obtained polyether polyamide resin has flexibility and fuel barrier properties. It will be excellent.

<Other diamine compounds>
The diamine structural unit constituting the polyether polyamide (b) is derived from the polyether diamine compound (b-1) and xylylenediamine (b-2) represented by the general formula (1) as described above. Although a structural unit is included, the structural unit derived from other diamine compounds may be included as long as the effects of the present invention are not impaired.
Examples of diamine compounds that can constitute diamine structural units other than the polyetherdiamine compound (b-1) and xylylenediamine (b-2) include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, Aliphatic diamines such as heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine; 3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4 -A Nocyclohexyl) propane, bis (aminomethyl) decalin, alicyclic diamines such as bis (aminomethyl) tricyclodecane; aromatic rings such as bis (4-aminophenyl) ether, paraphenylenediamine, bis (aminomethyl) naphthalene Examples of diamines having ss are not limited thereto.

(Dicarboxylic acid structural unit)
The dicarboxylic acid structural unit constituting the polyether polyamide (b) includes a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms.
In the dicarboxylic acid structural unit, the content of the structural unit derived from the α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms is preferably 50 to 100 mol%, more preferably. 70 to 100 mol%.
Examples of the α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and 1,10-decane. Examples include dicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, and the like. Among these, at least one selected from adipic acid and sebacic acid is preferable from the viewpoints of crystallinity and high elasticity, and sebacic acid is more preferable from the viewpoint of flexibility. These dicarboxylic acids may be used alone or in combination of two or more.

<Other dicarboxylic acids>
The dicarboxylic acid structural unit constituting the polyether polyamide (b) includes a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms, as described above. As long as the effects of the present invention are not impaired, structural units derived from other dicarboxylic acids may be included.
Examples of the dicarboxylic acid that can constitute the dicarboxylic acid constituent unit other than the α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms include aliphatic dicarboxylic acids such as oxalic acid and malonic acid; terephthalic acid Examples thereof include aromatic dicarboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid, but are not limited thereto.
When a mixture of an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms and isophthalic acid is used as the dicarboxylic acid component, the heat resistance and molding processability of the polyether polyamide (b) Can be improved. The molar ratio of α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms and isophthalic acid (α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms) / Isophthalic acid) is preferably 50/50 to 99/1, more preferably 70/30 to 95/5.

(Physical properties of polyether polyamide (b))
The polyether polyamide (b) is a highly crystalline polyamide block formed from xylylenediamine (b-2) and an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms. By making the hard block and the polyether block derived from the polyether diamine compound (b-1) as a soft segment, it is excellent in melt moldability and moldability. Furthermore, the obtained polyether polyamide is excellent in toughness, flexibility, crystallinity, heat resistance and the like.

The relative viscosity of the polyether polyamide (b) is preferably in the range of 1.1 to 3.0, more preferably in the range of 1.1 to 2.9 from the viewpoints of moldability and melt mixing with other resins. More preferably, it is in the range of 1.1 to 2.8. The relative viscosity was determined by dissolving 0.2 g of a sample in 20 mL of 96% sulfuric acid and measuring the drop time (t) measured at 25 ° C. with a Cannon-Fenske viscometer and the drop time (t) of 96% sulfuric acid itself measured in the same manner. ₀ ) and is expressed by the following equation.
Relative viscosity = t / t ₀

  The melting point of the polyether polyamide (b) is preferably in the range of 170 to 270 ° C., more preferably in the range of 175 to 270 ° C., still more preferably in the range of 180 to 270 ° C., and still more preferably in the range of 180 to 270 ° C. from the viewpoint of heat resistance. The range is 260 ° C. The melting point is measured using a differential scanning calorimeter.

From the viewpoint of flexibility, the tensile elongation at break (measurement temperature 23 ° C., humidity 50% RH) of the polyether polyamide (b) is preferably 100% or more, more preferably 200% or more, and still more preferably 250% or more. More preferably, it is 300% or more.
The tensile modulus (measuring temperature 23 ° C., humidity 50% RH) of the polyether polyamide (b) is preferably 100 MPa or more, more preferably 200 MPa or more, still more preferably 300 MPa or more, from the viewpoint of flexibility and mechanical strength. Preferably it is 400 MPa or more, More preferably, it is 500 MPa or more.
Measurement of tensile modulus and tensile elongation at break is performed according to JIS K7161.

The number average molecular weight (Mn) of the polyether polyamide (b) is preferably 1000 to 50000, more preferably 3000 to 30000, still more preferably 5000 to 25000, and still more preferably 7000 to 22000.
In addition, the number average molecular weight (Mn) of polyether polyamide (b) means the value measured by the method as described in an Example.

(Production of polyether polyamide (b))
Manufacture of polyether polyamide (b) is not specifically limited, It can carry out by arbitrary methods and superposition | polymerization conditions. For example, a diamine component (a diamine such as a polyetherdiamine compound (b-1) and xylylenediamine (b-2)) and a dicarboxylic acid component (an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms (b -3) and other dicarboxylic acid) are heated in a pressurized state in the presence of water, and polyether polyamide (b) is produced by polymerizing in a molten state while removing added water and condensed water. can do. Further, a diamine component (a diamine such as a polyetherdiamine compound (b-1) and xylylenediamine (b-2)) is a dicarboxylic acid component in a molten state (an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms). The polyether polyamide (b) can also be produced by a method in which it is directly added to the acid (dicarboxylic acid such as b-3) and polycondensed under normal pressure. In this case, in order to keep the reaction system in a uniform liquid state, the diamine component is continuously added to the dicarboxylic acid component, and the reaction system is heated up so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide. However, polycondensation proceeds.
At this time, among the diamine components, the polyether diamine compound (b-1) may be previously charged in the reaction tank together with the dicarboxylic acid component. By preparing the polyether diamine compound (b-1) in the reaction vessel in advance, thermal degradation of the polyether diamine compound (b-1) can be suppressed. Also in that case, in order to keep the reaction system in a uniform liquid state, a diamine component other than the polyether diamine compound (b-1) is continuously added to the dicarboxylic acid component, and during this time, an oligoamide and a polyamide that generate a reaction temperature. The polycondensation proceeds while the temperature of the reaction system is raised so that it does not fall below the melting point.

  Diamine component (diamine such as polyether diamine compound (b-1) and xylylenediamine (b-2)) and dicarboxylic acid component (α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms (b- 3) and the like (diamine component / dicarboxylic acid component) is preferably in the range of 0.9 to 1.1, more preferably in the range of 0.93 to 1.07, and still more preferably 0. The range is from .95 to 1.05, more preferably from 0.97 to 1.02. If the molar ratio is within the above range, high molecular weight tends to proceed.

  The polymerization temperature is preferably 150 to 300 ° C, more preferably 160 to 280 ° C, still more preferably 170 to 270 ° C. When the polymerization temperature is within the above temperature range, the polymerization reaction proceeds rapidly. In addition, since the thermal decomposition of monomers, oligomers in the middle of polymerization, polymers, and the like hardly occurs, the resulting polyether polyamide has good properties.

  The polymerization time is usually 1 to 5 hours after the diamine component starts to be dropped. By setting the polymerization time within the above range, the molecular weight of the polyether polyamide (b) can be sufficiently increased, and coloring of the obtained polyether polyamide (b) can be suppressed.

  The polyether polyamide (b) is preferably produced by a melt polycondensation (melt polymerization) method by adding a phosphorus atom-containing compound. As the melt polycondensation method, a method in which a diamine component is dropped into a dicarboxylic acid component melted at normal pressure and polymerized in a molten state while removing condensed water is preferable.

  In the polycondensation system of the polyether polyamide (b), a phosphorus atom-containing compound can be added as long as the characteristics are not inhibited. Phosphorus atom-containing compounds that can be added include dimethylphosphinic acid, phenylmethylphosphinic acid, hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, calcium hypophosphite, ethyl hypophosphite , Phenylphosphonous acid, sodium phenylphosphonite, potassium phenylphosphonite, lithium phenylphosphonite, ethyl phenylphosphonite, phenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphonate, potassium phenylphosphonate, phenylphosphone Lithium phosphate, diethyl phenylphosphonate, sodium ethylphosphonate, potassium ethylphosphonate, phosphorous acid, sodium hydrogen phosphite, sodium phosphite, triethyl phosphite, triphenyl phosphite, pyrophosphorous acid etc. Raising Of these, metal hypophosphites such as sodium hypophosphite, potassium hypophosphite, and lithium hypophosphite are particularly effective in promoting the amidation reaction and are excellent in coloration prevention effects. It is preferably used, and sodium hypophosphite is particularly preferable. The phosphorus atom-containing compounds that can be used in the present invention are not limited to these compounds. The amount of the phosphorus atom-containing compound added to the polycondensation system is preferably 1 to 1000 ppm, more preferably in terms of phosphorus atom concentration in the polyether polyamide (b), from the viewpoint of good appearance and moldability. It is 5-1000 ppm, More preferably, it is 10-1000 ppm.

  Further, it is preferable to add an alkali metal compound in combination with the phosphorus atom-containing compound into the polycondensation system of the polyether polyamide (b). To prevent coloring of the polymer during polycondensation, a sufficient amount of the phosphorus atom-containing compound needs to be present, but in some cases it may lead to gelation of the polymer, so that the amidation reaction rate is adjusted. In addition, it is preferable to coexist an alkali metal compound. As the alkali metal compound, an alkali metal hydroxide or an alkali metal acetate is preferable. Examples of the alkali metal compound that can be used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, lithium acetate, sodium acetate, potassium acetate, rubidium acetate, cesium acetate, and the like. However, it can be used without being limited to these compounds. When an alkali metal compound is added to the polycondensation system, the value obtained by dividing the number of moles of the compound by the number of moles of the phosphorus atom-containing compound is preferably 0.5 to 1, more preferably 0.8. It is 55-0.95, More preferably, it is 0.6-0.9. Within the above range, there is an effect of moderately suppressing the promotion of the amidation reaction of the phosphorus atom-containing compound. By suppressing the reaction too much, the polycondensation reaction rate decreases, the thermal history of the polymer increases, An increase in gelation can be avoided.

  The polyether polyamide (b) obtained by melt polycondensation is once taken out, pelletized, and dried before use. In order to further increase the degree of polymerization, solid phase polymerization may be performed. As a heating device used in drying or solid-phase polymerization, a continuous heating drying device, a tumble dryer, a conical dryer, a rotary drum type heating device called a rotary dryer, etc., and a rotary blade inside a nauta mixer Although a conical heating apparatus provided with can be used suitably, a well-known method and apparatus can be used without being limited to these.

[Layer structure and forming method]
The multilayer structure of the present invention comprises a polyolefin layer (A) (hereinafter sometimes abbreviated as (A) layer) and a polyether polyamide layer (B) (hereinafter sometimes abbreviated as (B) layer). , Each can have one or more layers. Specifically, the following layer configurations are mentioned, and a layer configuration in which coextrusion is performed with a multilayer die using an extruder is preferable.
(1) Two-type two-layer configuration; specifically, (A) layer / (B) layer, (B) layer / (A) layer, and the like.
(2) Two types and three layers; specifically, (A) layer / (B) layer / (A) layer, (B) layer / (A) layer / (B) layer, and the like.
(3) 2 types, 4 layers configuration; specifically, (A) layer / (B) layer / (A) layer / (B) layer, (B) layer / (A) layer / (B) layer / ( A) Layer etc.
In the present specification, when the multilayer structure is a cylindrical molded body, for example, the notation X / Y / Z indicates that the layers are laminated in the order of X, Y, and Z from the inside unless otherwise specified. When the multilayer structure has a plurality of (A) layers, the plurality of (A) layers may be the same or different, and the same applies to the (B) layer.

In addition, the multilayer structure of the present invention is preferably a cylindrical molded body because of its characteristics. As the cylindrical molded body, for example, a cylindrical shape such as a pipe, a hose, or a tube, and the inside is hollow, and liquid or gas can be moved from one to the other in the hollow portion. .
When the multilayer structure is a cylindrical molded body, from the viewpoint of fuel barrier properties, weather resistance, chlorine resistance, etc., from the hollow portion of the cylindrical molded body, that is, from the inside, the order of (A) layer and (B) layer It is preferable to have at least a layer structure.
The layer structure may be selected according to the usage of the cylindrical molded body, but from the viewpoint of the balance between flexibility and fuel barrier property and economy, two types of (A) layer / (B) layer from the inside. A two-layer structure and a two-layer three-layer structure of (A) layer / (B) layer / (A) layer are more preferable.

What is necessary is just to specify the thickness of a cylindrical molded object suitably according to a use.
The thickness of the polyether polyamide layer (B) is preferably 10 μm or more, more preferably 30 μm or more, and further preferably 50 μm or more. When the thickness of the polyether polyamide layer (B) is 10 μm or more, the effect of fuel barrier properties is suitably exhibited.
Further, the ratio of the thickness of the polyether polyamide layer (B) to the thickness of the cylindrical molded body is preferably 0.005 to 0.5, more preferably 0.008 to 0.2, and 0 More preferably, it is 0.01-0.1. If the thickness of the polyether polyamide layer (B) with respect to the thickness of the cylindrical molded body is 0.005 or more, sufficient fuel barrier properties can be exhibited, and if it is 0.5 or less, flexibility and fuel barrier properties are exhibited. And a good moldability when making a cylindrical molded body.

  The method for forming the cylindrical molded body is not particularly limited, and can be manufactured by employing a known technique. For example, each resin constituting each layer may be melt-kneaded and supplied to a multilayer tube extruder having a die capable of forming each molten resin into a multilayer structure, and molded according to a conventional method. In addition, an inner layer made of a polyolefin layer (A) is molded into a predetermined shape in advance, and then coated with a polyether polyamide (b) melted from a crosshead die or the like, a polyether polyamide layer (B) is provided, and (A ) Layer / (B) layer, and the multilayer structure is coated with a polyolefin (A) layer, and the multilayer structure of (A) layer / (B) layer / (A) layer from the inside. It is also good.

  When melt-kneading the polyolefin resin that is the main component of the polyolefin layer (A) and extruding the polyolefin layer (A), the extrusion temperature is equal to or higher than the melting point of the polyolefin resin that is the main component. It is preferable to set the temperature within a range of 150 ° C. or higher than the melting point of the polyolefin resin, 20 ° C. higher than the melting point of the main component polyolefin resin, and 120 ° C. or lower than the melting point of the main component polyolefin resin. It is more preferable to set. By setting the extrusion temperature to be equal to or higher than the melting point of the polyolefin resin, solidification of the polyolefin resin can be suppressed, and by setting the extrusion temperature to 150 ° C. or lower than the melting point of the polyolefin resin, thermal degradation of the polyolefin resin can be suppressed. .

  When the polyether polyamide (b), which is the main component of the polyether polyamide layer (B), is melt-kneaded and the polyether polyamide layer (B) is extruded, the extrusion temperature is changed to the polyether polyamide, which is the main component. It is preferable to set it in a range not lower than the melting point of (b) and not more than 80 ° C. higher than the melting point of the polyether polyamide (b) as the main component, and 10 ° C. higher than the melting point of the polyether polyamide (b) as the main component. It is more preferable that the temperature is set to a temperature not higher than 60 ° C. higher than the melting point of the polyether polyamide (b) as the main component. By setting the extrusion temperature to be equal to or higher than the melting point of the polyether polyamide (b), solidification of the polyether polyamide (b) can be suppressed, and the temperature is set within a range of 80 ° C. or higher than the melting point of the polyether polyamide (b). By doing so, thermal degradation of the polyether polyamide (b) can be suppressed.

  When the polyolefin layer (A) and the polyether polyamide layer (B) are laminated in a multilayer tube extruder, the temperature of the resin flow path after lamination is equal to or higher than the melting point of the polyether polyamide (b) and is the main component. It is preferable to set the temperature within a range of 80 ° C. or higher than the melting point of a certain polyether polyamide (b), and a temperature that is 10 ° C. or more higher than the melting point of the polyether polyamide (b) as the main component and the polyether as the main component. It is more preferable to set the temperature within a range of 60 ° C. or higher than the melting point of the polyamide (b). By setting the temperature of the resin flow path after lamination to the melting point of the polyether polyamide (b) or higher, the solidification of the polyether polyamide (b) can be suppressed, which is 80 ° C. higher than the melting point of the polyether polyamide (b). By setting in the range below the temperature, the thermal degradation of the polyether polyamide (b) can be suppressed.

In addition to the polyolefin layer (A) and the polyether polyamide layer (B) described above, the multilayer structure of the present invention can be extruded to give necessary characteristics without impairing the effects of the present invention. A simple resin layer can be provided.
Examples of the resin layer include those formed from a thermoplastic resin such as maleic anhydride-modified polyolefin resin, fluororesin, polyimide resin, polyamide resin, polyester resin, polystyrene resin, and vinyl chloride resin.

Moreover, the above-mentioned polyolefin layer (A) and polyether polyamide layer (B) constituting the multilayer structure of the present invention, and the resin layer that can be provided as necessary, are added within a range not impairing the effects of the present invention. An agent may be included.
Additives include fillers, stabilizers, colorants, UV absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, crystallization accelerators, fibrous reinforcements, plasticizers, lubricants, heat resistance Examples include, but are not limited to, agents. Moreover, what is necessary is just to use the content of an additive in the range of the normal content according to the kind.
When laminating from the inside as the (A) layer / (B) layer / (A ′) layer, the types of additives in the inner (A) layer, the intermediate (B) layer, and the outer (A ′) layer The amount may be different. For example, the combination of the colorants of the inner (A) layer and the outer (A ′) layer can be changed to facilitate discrimination from other resin tubes.

  The multilayer structure of the present invention has the above-mentioned polyolefin layer (A) and polyether polyamide layer (B), and is excellent in flexibility and fuel barrier properties without losing excellent flexibility and lightweight made of polyolefin. Has characteristics. For this reason, the multilayer structure is convenient for piping work that is bent as desired, and prevents penetration of fuel such as kerosene, even if it is wound around a core to be transported This is particularly suitable as a water supply pipe that does not require a coating material for water supply.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In the examples and comparative examples, various evaluations were performed by the following methods.

(1) Flexibility evaluation The cylindrical molded bodies obtained in Examples and Comparative Examples were wound around a core having a diameter of 600 mm and left at 23 ° C. for 24 hours. The subsequent cylindrical molded body was removed from the winding core, and whether or not wrinkles were generated was visually evaluated.

(2) Petroleum odor evaluation (fuel barrier properties)
The cylindrical molded bodies obtained in Examples and Comparative Examples were wound around a core having a diameter of 600 mm, fixed in a container filled with kerosene so that the half circumference was immersed in kerosene, and left at 23 ° C. for 1 week. . Thereafter, tap water was put into the cylindrical molded body while being immersed in kerosene, and was further left for 24 hours. Then, tap water was extracted, and the odor of kerosene was evaluated for the extracted tap water.

Various measurements in the production examples and comparative production examples were performed by the following methods.
(1) Relative viscosity (ηr)
A 0.2 g sample was precisely weighed and dissolved in 20 ml of 96% sulfuric acid at 20-30 ° C. with stirring. After complete dissolution, 5 ml of the solution was quickly taken into a Cannon Fenceke viscometer, and left for 10 minutes in a thermostatic bath at 25 ° C., and then the drop time (t) was measured. Further, the dropping time (t ₀ ) of 96% sulfuric acid itself was measured in the same manner. The relative viscosity was calculated from t and t _{0 according} to the following formula.
Relative viscosity = t / t ₀

(2) Number average molecular weight (Mn)
First, the sample was dissolved in a phenol / ethanol mixed solvent and a benzyl alcohol solvent, respectively, and the carboxyl end group concentration and amino end group concentration were determined by neutralization titration with hydrochloric acid and sodium hydroxide aqueous solution. The number average molecular weight was determined by the following formula from the quantitative values of the amino end group concentration and the carboxyl end group concentration.
Number average molecular weight = 2 × 1,000,000 / ([NH ₂ ] + [COOH])
[NH ₂ ]: Amino end group concentration (μeq / g)
[COOH]: Carboxyl end group concentration (μeq / g)

(3) Differential scanning calorimetry (glass transition temperature, crystallization temperature and melting point)
The differential scanning calorific value was measured according to JIS K7121 and K7122. Using a differential scanning calorimeter (manufactured by Shimadzu Corporation, trade name: “DSC-60”), each sample was charged into a DSC measurement pan and heated to 300 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere. The measurement was performed after the pre-cooling pretreatment. The measurement conditions were a temperature rising rate of 10 ° C./min and holding at 300 ° C. for 5 minutes, and then a temperature falling rate of −5 ° C./min was measured up to 100 ° C., and the glass transition temperature Tg, crystallization temperature Tch and melting point Tm were Asked.

[Production of polyetheramide]
What was manufactured by the following manufacture examples was used as polyether amide which forms the polyether polyamide layer (B) in an Example.
(Production Example 1) Production of polyether polyamide b1 In a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet, 768.55 g of sebacic acid and 0.6644 g of sodium hypophosphite monohydrate And 0.4628 g of sodium acetate were charged and the inside of the container was sufficiently replaced with nitrogen, and then melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. While gradually raising the temperature to 260 ° C., 344.18 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 147.50 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( According to the molar ratio (MXDA: PXDA = 70: 30)) and polyether diamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) ED-900, US HUNTSMAN), the general formula (1-2) —OR ¹ — is —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃ ) —, the approximate number of x2 + z2 is 6.0, the approximate number of y2 is 12.5, and the approximate molecular weight is 900. There was added 171.00 g of the mixed solution dropwise, followed by polymerization for about 2 hours to obtain polyether polyamide b1. Relative viscosity = 1.48, [COOH] = 66.91 μeq / g, [NH ₂ ] = 82.80 μeq / g, Mn = 13360, Tg = 27.6 ° C., Tch = 72.8 ° C., Tm = 207. 6 ° C.

(Production Example 2) Production of polyether polyamide b2 In a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet, 687.65 g of sebacic acid and 0.6612 g of sodium hypophosphite monohydrate Then, 0.4605 g of sodium acetate was charged and the inside of the container was sufficiently replaced with nitrogen, and then melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. While gradually raising the temperature to 260 ° C., 291.74 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 125.03 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( Molar ratio (MXDA: PXDA = 70: 30)) and polyetherdiamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) ED-900, details are the same as above) 306.00 g of a mixed solution was added dropwise for about 2 hours. Polymerization was performed to obtain polyether polyamide b2. Relative viscosity = 1.36, [COOH] = 66.35 μeq / g, [NH ₂ ] = 74.13 μeq / g, Mn = 14237, Tg = 16.9 ° C., Tch = 52.9 ° C., Tm = 201. 9 ° C.

Production Example 3 Production of Polyether Polyamide b3 In a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet, 748.33 g of sebacic acid, sodium hypophosphite monohydrate 6565 g and sodium acetate 0.4572 g were charged and the inside of the container was sufficiently purged with nitrogen, and then melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. While gradually raising the temperature to 260 ° C., 335.12 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 143.62 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( According to the molar ratio (MXDA: PXDA = 70: 30)) and polyether diamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) XTJ-542, HUNTSMAN, USA), in the general formula (1-1) —OR ¹ — is —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃ ) —, the approximate number of x1 + z1 is 6.0, the approximate number of y1 is 9.0, and the approximate molecular weight is 1000. 185.00 g of a mixed solution was dropped and polymerization was carried out for about 2 hours to obtain polyether polyamide b3. Relative viscosity = 1.45, [COOH] = 55.19 μeq / g, [NH ₂ ] = 70.61 μeq / g, Mn = 15898, Tg = 50.3 ° C., Tch = 83.0 ° C., Tm = 208. 1 ° C.

(Production Example 4) Production of polyether polyamide b4 In a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet, 657.68 g of adipic acid and 0.6626 g of sodium hypophosphite monohydrate Then, 0.4578 g of sodium acetate was charged and the inside of the container was sufficiently purged with nitrogen, and then melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. While gradually raising the temperature to 260 ° C., 407.58 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 174.68 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( Molar ratio (MXDA: PXDA = 70: 30)) and polyetherdiamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) ED-900, details are the same as above) 202.50 g of a mixed solution was added dropwise for about 2 hours. Polymerization was performed to obtain polyether polyamide b4. Relative viscosity = 1.51, [COOH] = 48.53 μeq / g, [NH ₂ ] = 88.72 μeq / g, Mn = 14572, Tg = 59.5 ° C., Tch = 98.0 ° C., Tm = 249. 9 ° C.

In the comparative example, instead of the polyether polyamide layer (B), a layer formed from polyether amide b5 and polyamide b6 produced in the following comparative production example was used.
(Comparative Production Example 1) Production of polyether polyamide b5 12-aminolauric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 753.66 g in a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet. Adipic acid 56.84 g, sodium hypophosphite monohydrate 0.5798 g and sodium acetate 0.4038 g were charged, and after the inside of the container was sufficiently purged with nitrogen, it was melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. I let you. While gradually raising the temperature to 240 ° C., 388.89 g of polyetherdiamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) XTJ-542, the details are the same as above) was dropped, and polymerization was performed for about 2 hours. Ether polyamide b5 was obtained. Relative viscosity = 1.25, [COOH] = 87.27 μeq / g, [NH ₂ ] = 73.12 μeq / g, Mn = 1270, Tm = 165.0 ° C.

(Comparative Production Example 2) Production of polyamide b6 In a reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet, 829.2 g of sebacic acid, 0.6365 g of sodium hypophosphite monohydrate and 0.4434 g of sodium acetate was charged, and the inside of the container was sufficiently purged with nitrogen, and then melted at 170 ° C. while supplying nitrogen gas at 20 ml / min. While gradually raising the temperature to 260 ° C., 390.89 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 167.53 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( A mixed solution having a molar ratio (MXDA: PXDA = 70: 30)) was dropped and polymerization was carried out for about 2 hours to obtain a polyamide. Relative viscosity = 2.20, [COOH] = 81.8 μeq / g, [NH ₂ ] = 26.9 μeq / g, Mn = 18400, Tg = 65.9 ° C., Tch = 100.1 ° C., Tm = 213. 8 ° C.

[Examples 1 to 4]
Table 1 shows polyethylene that forms the polyolefin layer (A) (manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LL UF240, melting point 123 ° C.) and the polyether polyamide b1 to b4 that form the polyether polyamide layer (B). A cylindrical molded body was molded at a molding temperature shown in Table 1 using a multilayer tube extruder having two extruders and a flow path for forming a multilayer structure of two types and three layers.
This cylindrical molded body has a thickness of 5 mm and has a layer configuration of (A) layer / (B) layer / (A) layer from the inside. The cylindrical molded body has an outer diameter of 30 mm and an inner diameter of 20 mm. ) Layer thickness was 0.2 mm, and the inner and outer (A) layers were formed to have uniform thickness.
The obtained cylindrical molded body was evaluated as described above, and the results are shown in Table 1.

[Comparative Example 1]
Using a polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LL UF240, melting point 123 ° C.), a cylindrical molded body is molded at a molding temperature shown in Table 1 using a single-layer tube extruder comprising one extruder. did.
This cylindrical molded body was molded to have a thickness of 5 mm, an outer diameter of 30 mm, and an inner diameter of 20 mm. The obtained cylindrical molded body was evaluated as described above, and the results are shown in Table 1.

[Comparative Examples 2 and 3]
Polyethylene forming the polyolefin layer (A) (manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LL UF240, melting point 123 ° C.) and the polyether polyamide b5 forming an intermediate layer provided in place of the polyether polyamide layer (B), Polyamide b6 (described as (B) layer in Table 1) is used as shown in Table 1, and is a multilayer tube extrusion molding comprising two extruders and a flow path for forming a multilayer structure of two types and three layers. A cylindrical molded body was molded at a molding temperature shown in Table 1.
This cylindrical molded body has a thickness of 5 mm and has a layer configuration of (A) layer / (B) layer / (A) layer from the inside. The cylindrical molded body has an outer diameter of 30 mm and an inner diameter of 20 mm. The thickness of the B) layer was 0.2 mm, and the thicknesses of the inner and outer (A) layers were uniform.
The obtained cylindrical molded body was evaluated as described above, and the results are shown in Table 1.

From Comparative Example 1, it can be seen that the conventional polyethylene single-layer cylindrical molded body is inferior in fuel barrier properties because petroleum penetrates into the interior and the tap water has a petroleum odor.
On the other hand, in Examples 1-4, since there is no wrinkle and there is no petroleum odor in tap water, the cylindrical molded body has a polyether polyamide layer (B), so that both flexibility and fuel barrier properties are achieved. It turns out that it is excellent.
Moreover, the polyether polyamide manufactured from the comparative examples 2 and 3 without using either a polyetherdiamine compound (b-1) or a xylylenediamine (b-2) instead of a polyether polyamide layer (B). Or it turns out that the cylindrical molded object which is excellent in both a softness | flexibility and fuel-barrier property is not obtained even if it has a layer which consists of polyamide.

  The multilayer structure of the present invention is a multilayer structure excellent in flexibility and fuel barrier properties without impairing excellent flexibility made of polyolefin. Therefore, since penetration of fuel such as kerosene can be prevented, it is suitable as a water pipe buried in the ground, particularly as a water supply pipe.

Claims (9)

A polyether diamine compound having a polyolefin layer (A) and a polyether polyamide layer (B), wherein the polyether polyamide layer (B) has a diamine structural unit represented by the following general formula (1) A structural unit derived from (b-1) and xylylenediamine (b-2), wherein the dicarboxylic acid structural unit is derived from an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms. A multilayer structure containing a polyether polyamide (b) containing a structural unit.

(In the formula, x + z represents 1 to 60, y represents 1 to 50, and —OR ¹ — represents each independently —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH ( CH ₃ ) — and —OR ² — represents —OCH ₂ CH ₂ CH ₂ CH ₂ — or —OCH ₂ CH ₂ —. The multilayer structure according to claim 1, wherein the polyetherdiamine compound (b-1) is represented by the following general formula (1-1) or (1-2).

(In general formula (1-1), x1 + z1 represents 1 to 60, y1 represents 1 to 50, and —OR ¹ — represents —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH. ₂ represents CH (CH ₃ ) —.
In general formula (1-2), x2 + z2 represents 1 to 60, y2 represents 1 to 50, and —OR ¹ — represents —OCH ₂ CH ₂ CH ₂ —, —OCH (CH ₃ ) CH ₂ — or —OCH _2. CH (CH ₃ ) — is represented. )   The multilayer structure according to claim 1 or 2, wherein the xylylenediamine (b-2) is metaxylylenediamine, paraxylylenediamine, or a mixture thereof.   The multilayer structure according to any one of claims 1 to 3, wherein the α, ω-linear aliphatic dicarboxylic acid (b-3) is at least one selected from adipic acid, sebacic acid, and a mixture thereof.   The multilayer structure in any one of Claims 1-4 which has a polyolefin layer (A) and a polyether polyamide layer (B) 1 layer or 2 layers or more, respectively.   The multilayer structure in any one of Claims 1-5 whose multilayer structure is a cylindrical molded object.   The multilayer structure according to claim 6, which has at least a layer structure in the order of a polyolefin layer (A) and a polyether polyamide layer (B) from the inside.   The multilayer structure according to claim 6 or 7, wherein the ratio of the thickness of the polyether polyamide layer (B) to the thickness of the cylindrical molded body is 0.005 to 0.5.   The multilayer structure according to any one of claims 6 to 8, which is a water pipe.