JP6136490B2 - Multilayer structure - Google Patents

Description

  The present invention relates to a multilayer structure excellent in pinhole resistance, oxygen barrier properties and interlayer adhesion strength.

A resin having an oxygen barrier property is used as a food packaging material in order to suppress deterioration such as alteration, rot, and oxidation of food due to oxygen. Among them, polymetaxylylene adipamide (MXD6) is known as a resin having excellent oxygen barrier properties, and is used as a packaging material for a wide variety of foods.
On the other hand, since MXD6 is inferior in flexibility and has poor pinhole resistance, various studies have been conducted to make food packaging materials exhibiting high gas barrier properties while improving deterioration of pinhole resistance. For example, Patent Document 1 proposes a laminated film in which a polyamide layer containing a specific fatty acid bisamide and a modified polyolefin in a specific ratio is laminated on both sides of the MXD6 layer. As the polyamide layer, nylon 6 is used in the example of Patent Document 1, and the layer structure of nylon 6 / adhesive / MXD6 / adhesive / nylon 6 has a thickness of 45/5/50/5. A laminated film obtained by stretching an unstretched sheet of / 45 μm to a thickness of 15 μm with a biaxial stretching machine is disclosed.

JP 2007-136874 A

  However, since nylon 6 is inferior in oxygen barrier property, the MXD6 layer needs to have a certain thickness or more. Moreover, in order to obtain the interlayer adhesion of the laminated film, it was necessary to laminate nylon 6 and MXD6 through an adhesive layer. Thus, it has not yet reached a laminated film satisfying all of pinhole resistance, oxygen barrier properties and interlayer adhesion strength, and there is room for improvement in the above characteristics of the laminated film having oxygen barrier properties.

  An object of the present invention is to provide a multilayer structure having a polyamide layer having oxygen barrier properties such as MXD6 and having excellent pinhole resistance, oxygen barrier properties and interlayer adhesion strength.

The present inventors have found that the above-mentioned problems can be solved by using at least one layer of the multilayer structure as a specific polyether polyamide layer in a multilayer structure such as a sheet or a film, and reached the present invention.
That is, the present invention relates to the following multilayer structure.

<1> A multilayer structure having a polyamide layer (A) and a polyether polyamide layer (B),
The polyamide layer (A) includes a structural unit in which the diamine structural unit is derived from xylylenediamine (a-1), and the dicarboxylic acid structural unit is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms ( a polyamide (a) containing a structural unit derived from a-2),
The polyether polyamide layer (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): A multilayer structure containing a polyether polyamide (b) containing a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (b-3) having 4 to 20 carbon atoms as a dicarboxylic acid 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 —.

<2> The multilayer structure which is a sheet or a film.

  The present invention can provide a multilayer structure excellent in pinhole resistance, oxygen barrier property and interlayer adhesion strength by providing at least one layer of the multilayer structure having a specific polyether polyamide layer, and further providing food. It is possible to provide a sheet and a film having the above characteristics, which are suitable as a packaging material.

The multilayer structure of the present invention has at least a polyamide layer (A) and a polyether polyamide layer (B) as constituent layers. 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.

[Polyamide layer (A)]
The polyamide layer (A) is a layer containing polyamide (a) as a main component, and the polyamide (a) contains a structural unit in which the diamine structural unit is derived from xylylenediamine (a-1), and is a dicarboxylic acid structural unit. Includes a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms.
By including the polyamide layer (A), the multilayer structure of the present invention can impart excellent oxygen barrier properties to the multilayer structure.

(Diamine structural unit)
The content of the structural unit derived from xylylenediamine (a-1) in the diamine structural unit is preferably 70 to 100 mol%, more preferably 80 to 100 mol%, still more preferably 90 to 100 mol%. is there.
As xylylenediamine (a-1), metaxylylenediamine, paraxylylenediamine or a mixture thereof is preferable, metaxylylenediamine or a mixture of metaxylylenediamine and paraxylylenediamine is more preferable, Xylylenediamine is more preferred.

When metaxylylenediamine is used as xylylenediamine (a-1), the resulting polyamide has an improved oxygen barrier property and excellent crystallinity, melt moldability, moldability, and toughness. .
Moreover, when using a mixture of metaxylylenediamine and paraxylylenediamine as xylylenediamine (a-1), the ratio of paraxylylenediamine to the total amount of metaxylylenediamine and paraxylylenediamine is: Preferably it is 90 mol% or less, More preferably, it is 1-80 mol% or less, More preferably, it is 1-70 mol% or less, More preferably, it is 5-70 mol%.

As described above, the diamine structural unit constituting the polyamide (a) includes a structural unit derived from xylylenediamine (a-1), but other diamine compounds as long as the effects of the present invention are not impaired. The structural unit derived from may be included.
Examples of diamine compounds that can constitute diamine structural units other than xylylenediamine (a-1) include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, and nonamethylene. Aliphatic diamines such as diamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1 , 4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (amino Illustrate alicyclic diamines such as methyl) decalin and bis (aminomethyl) tricyclodecane; diamines having aromatic rings such as bis (4-aminophenyl) ether, paraphenylenediamine and bis (aminomethyl) naphthalene However, it is not limited to these. These diamine compounds may be used alone, in combination of two or more kinds, or in combination with xylylenediamine.

(Dicarboxylic acid structural unit)
The content of the structural unit derived from the α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms in the dicarboxylic acid structural unit is preferably 70 to 100 mol%, more preferably 80. It is -100 mol%, More preferably, it is 90-100 mol%.
Examples of the α, ω-linear aliphatic dicarboxylic acid (a-2) 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 viewpoint of crystallinity and high elasticity, and adipic acid is more preferable from the viewpoint of gas barrier properties in addition to crystallinity and high elasticity. These dicarboxylic acids may be used alone or in combination of two or more.

As described above, the dicarboxylic acid structural unit constituting the polyamide (a) includes a structural unit derived from an α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms. As long as the effect is not impaired, other structural units derived from dicarboxylic acids may be included.
Examples of dicarboxylic acids that can be used in addition to the α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms include aliphatic dicarboxylic acids such as oxalic acid and malonic acid; terephthalic acid, isophthalic acid, 2 An aromatic dicarboxylic acid such as 1,6-naphthalenedicarboxylic acid can be exemplified, but is not limited thereto. These dicarboxylic acids may be used alone or in combination of two or more, or may be used in combination with an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms.
Further, when a mixture of α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms and isophthalic acid is used, the heat resistance and molding processability of polyamide resin (A) should be improved. Can do. The molar ratio of α, ω-linear aliphatic dicarboxylic acid (a-2) having 4 to 20 carbon atoms and isophthalic acid (α, ω-linear aliphatic dicarboxylic acid (a-2) 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 polyamide (a))
The melting point of the polyamide (a) 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., more preferably from the viewpoints of heat resistance and melt moldability. It is the range of 180-260 degreeC. The melting point is measured using a differential scanning calorimeter.
The relative viscosity of the polyamide (a) is preferably in the range of 1.7 to 4.0, more preferably in the range of 1.9 to 3.8 from the viewpoints of moldability and melt mixing with other resins. . The relative viscosity was obtained by dissolving 0.2 g of a sample in 20 mL of 96 mass% sulfuric acid and measuring the drop time (t) measured at 25 ° C. with a Canon Fenske viscometer, and the drop time of 96 mass% sulfuric acid itself measured in the same manner. It is the ratio of (t ₀ ) and is shown by the following equation.
Relative viscosity = t / t ₀

In the present invention, polymetaxylylene adipamide (MXD6), polymetaxylylene adipamide isophthalamide (MXD6I) and the like are preferably used as the polyamide (a).
Among the polyamides (a), MXD6 in which xylylenediamine (a-1) is metaxylylenediamine and α, ω-linear aliphatic dicarboxylic acid (a-2) is adipic acid is particularly preferable. is there. By using MXD6 as the polyamide (a), it is possible to impart more excellent gas barrier properties to the multilayer structure of the present invention, and it is possible to improve strength, elastic modulus, moldability, and the like.

[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 impart flexibility to the multilayer structure, has excellent pinhole resistance, and the polyether polyamide layer (B) itself has oxygen barrier properties. Therefore, by laminating together with the polyamide layer (A), a multilayer structure having a further excellent oxygen barrier property can be obtained. Moreover, since the polyether polyamide layer (B) has adhesiveness, the multilayer structure is excellent in interlayer adhesion strength without having an adhesive 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). (X + z) in the above general formula (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. 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 7000, more preferably 200 to 5000, still more preferably 300 to 3500, still more preferably 400 to 2500, 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 and can suppress the generation of pinholes when bent can be obtained.

  The polyether diamine compound (b-1) represented by the general formula (1) is represented by the following general formula (1-1) from the viewpoint of a multilayer structure having more excellent gas barrier properties, pinhole resistance and interlayer adhesion strength. ) Or a polyetherdiamine compound represented by (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, further preferably 2 to 20, and still more preferably 2 to 15. . 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 to 60, preferably 2 to 40, more preferably 2 to 30, further preferably 2 to 20, and still more preferably 2 to 15. . 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, Xylylenediamine is more preferred.
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 70 mol% or less. 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 1 to 50 mol%, more preferably 1 to 30 mol%, still more preferably. 1 to 25 mol%, still more preferably 1 to 8 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 polyamide resin composition has flexibility, gas barrier properties, Excellent pinhole resistance and interlayer adhesion strength.

<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 viewpoint of crystallinity and high elasticity, and adipic acid is more preferable from the viewpoint of gas barrier properties in addition to crystallinity and high elasticity. 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, gas barrier properties, pinhole resistance, interlayer adhesion strength, 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 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 polyamide 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 this specification, for example, the notation X / Y / Z indicates that the layers are stacked in the order of X, Y, and Z from the side exposed to air 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, when the multilayer structure of the present invention is applied as a food packaging material, from the viewpoint of pinhole resistance and oxygen barrier properties, the (B) layer is formed by laminating the (B) layer on both sides of the (A) layer. , (A) layer, (B) layer at least in order.

  The total thickness of the multilayer structure of the present invention may be appropriately specified according to the use, but when applied to a film of food packaging material, from the viewpoint of pinhole resistance, oxygen barrier property and interlayer adhesion strength, 3 to 500 μm. Preferably, it is 3 to 300 μm, more preferably 5 to 100 μm.

  Moreover, when applying to the film of a food packaging material as mentioned above, it is preferable that the thickness of (A) layer is 1-200 micrometers, It is more preferable that it is 1-100 micrometers, It is 3-50 micrometers. Further preferred. If the thickness of the (A) layer is 1 μm or more, sufficient oxygen barrier properties can be exhibited, and if it is 200 μm or less, a film having an excellent balance between oxygen barrier properties and pinhole resistance can be obtained. .

  Moreover, when applying to the film of a food packaging material as mentioned above, it is preferable that the thickness of (B) layer is 1-499 micrometers, it is more preferable that it is 1-300 micrometers, and it is 2-100 micrometers. Further preferred. If the thickness of the (B) layer is 1 μm or more, sufficient oxygen barrier properties and pinhole resistance can be exhibited, and if it is 499 μm or less, the film formability is excellent.

  Furthermore, the ratio of the thickness of the (B) layer to the thickness of the (A) layer is preferably 0.01 to 100, more preferably 0.1 to 30, and further preferably 1 to 10. preferable. If the thickness of the (B) layer relative to the thickness of the (A) layer is 0.01 or more, it can be a film having an excellent balance between oxygen barrier properties and pinhole resistance and having excellent interlayer adhesion strength, If it is 100 or less, it is excellent also in the moldability at the time of setting it as a film.

  The method for forming the multilayer structure is not particularly limited, and can be manufactured by employing a known technique. For example, each resin constituting each layer is melt-kneaded for each resin, and each molten resin is laminated and extruded from a die that can be formed into a multilayer structure to obtain an unstretched multilayer structure. The unstretched multilayer structure can be produced by simultaneous biaxial stretching or sequential biaxial stretching so as to obtain a molded body having a desired size. Furthermore, in order to give dimensional stability, you may heat-process at about 200 degreeC.

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

Moreover, the above-mentioned polyamide 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 reinforcing agents, 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.
In addition, when laminating as (B) layer / (A) layer / (B ′) layer, the types and amounts of additives added to the (B) layer, (A) layer, and (B ′) layer are different. May be.

  The multilayer structure of the present invention has the polyamide layer (A) and the polyether polyamide layer (B) described above, and has excellent characteristics of pinhole resistance, oxygen barrier properties, and interlayer adhesion strength. Therefore, the multilayer structure is suitable as a sheet and film used as food packaging materials such as pouches, squeezed containers, casings, and pillow packaging.

The following examples further illustrate the present invention, but the present invention is not limited to these examples.
In the examples and comparative examples, various evaluations were performed by the following methods.

(1) Oxygen barrier properties (oxygen permeation amount)
In accordance with JIS K7126, OX-TRAN (registered trademark) 2/21 (manufactured by MOCON) was used, and the oxygen permeation amount (unit: cc) of the stretched film having a total thickness of 25 μm produced under the conditions of 23 ° C. and 60% RH. / M ² · atm · day) was measured.

(2) Pinhole resistance (number of pinholes)
The produced stretched film having a total thickness of 25 μm is cut into a 210 mm square, and using Gelboflex (manufactured by Rigaku Kogyo Co., Ltd.), the axial direction of Gelboflex is the measurement direction, and the environment is 23 ° C. and 60% RH. Then, the number of pinholes at the time of bending 1000 times was measured. The pinhole was measured using a pinhole tester (weak current discharge method).

(3) Interlayer adhesion strength (existence of delamination)
In accordance with JIS K5600-5-6 (ISO 2409), the (B) layer is cut with a cutter into a grid of 2 mm intervals, and cellophane tape (registered trademark, manufactured by Nichiban Co., Ltd.) is applied to the cut portion. Affixing was performed within 0.5 minutes at an angle close to 60 degrees within 0.5 to 1.0 seconds, and the peeling state of the (B) layer was confirmed.
When even one of the 100 eyes peeled off, it was evaluated that there was peeling.

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

(2) Number average molecular weight (Mn)
First, the sample was dissolved in a mixed solvent of phenol and ethanol (phenol / ethanol = 4/1 (volume ratio)) and a benzyl alcohol solvent, respectively, and the carboxyl terminal group concentration and amino terminal group concentration were adjusted to hydrochloric acid and sodium hydroxide aqueous solution. It was determined by neutralization titration. 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 Adipic acid 650.37 g, sodium hypophosphite monohydrate 0.6125 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. Then, 0.4266 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., 588.04 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and polyether diamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) ED-900, According to the catalog of HUNTSMAN Inc. in the United States, —OR ¹ — in the general formula (1-2) is —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃ ) —, and the approximate number of x2 + z2 is 6 0.0, y2 is an approximate number of 12.5, and the approximate molecular weight is 900.) A 115.46 g mixed solution was added dropwise and polymerized for about 2 hours to obtain a polyether polyamide. Relative viscosity = 1.62, [COOH] = 49.02 μeq / g, [NH ₂ ] = 95.5 μeq / g, Mn = 13840, Tg = 68.1 ° C., Tch = 121.6 ° C., Tm = 234. 1 ° 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, 58.460 g of adipic acid and 0.5933 g of sodium hypophosphite monohydrate Then, 0.4133 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., 516.52 g of metaxylylenediamine (MXDA) (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and polyetherdiamine (manufactured by HUNTSMAN USA, Jeffamine (registered trademark) XTJ-542) According to the catalog of HUNTSMAN Inc. in the United States, —OR ¹ — in the general formula (1-1) is —OCH (CH ₃ ) CH ₂ — or —OCH ₂ CH (CH ₃ ) —, and the approximate number of x1 + z1 is 6 0.0, y1 is an approximate number of 9.0, and the approximate molecular weight is 1000). A mixture of 199.60 g was dropped and polymerization was carried out for about 2 hours to obtain a polyether polyamide. Relative viscosity = 1.53, [COOH] = 39.78 μeq / g, [NH ₂ ] = 106.93 μeq / g, Mn = 13632, Tg = 76.0 ° C., Tch = 111 ° C., Tm = 234. 3 ° 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, 613.83 g of adipic acid and 0.6242 g of sodium hypophosphite monohydrate And 0.4348 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., 380.41 g of metaxylylenediamine (MXDA) (Mitsubishi Gas Chemical Co., Ltd.) and 163.03 g of paraxylylenediamine (PXDA) (Mitsubishi Gas Chemical Co., Ltd.) ( Molar ratio (MXDA / PXDA = 70/30)) and polyetherdiamine (manufactured by HUNTSMAN, USA, Jeffamine (registered trademark) XTJ-542, details are the same as described above) 210.00 g of a mixed solution was added dropwise for about 2 hours. Polymerization was performed to obtain a polyether polyamide. Relative viscosity = 1.53, [COOH] = 79.95 μeq / g, [NH ₂ ] = 100.38 μeq / g, Mn = 111091, Tg = 80.5 ° C., Tch = 113.4 ° C., Tm = 252. 6 ° C.

(Production Example 4) Production of polyether polyamide b4 A reaction vessel having a volume of about 3 L equipped with a stirrer, a nitrogen gas inlet, and a condensed water outlet was provided with 584.6 g of adipic acid and 0.683 g of sodium hypophosphite monohydrate. Then, 0.476 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., 490.3 g of metaxylylenediamine (MXDA) (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and polyether diamine (manufactured by HUNTSMAN USA, Jeffamine (registered trademark) XTJ-542) (Details are the same as above) 400.00 g of a mixed solution was dropped and polymerization was carried out for about 2 hours to obtain a polyether polyamide. Relative viscosity = 1.38, [COOH] = 110.17 μeq / g, [NH ₂ ] = 59.57 μeq / g, Mn = 11783, Tg = 71.7 ° C., Tch = 108.3 ° C., Tm = 232. 8 ° C.

[ Examples 2 and 3 and Reference Examples 1 and 4 ]
Polymetaxylylene adipamide (trade name: “MX Nylon S6007”, relative viscosity 2.7, melting point 237 ° C., manufactured by Mitsubishi Gas Chemical Co., Inc.) forming the polyamide layer (A), and the polyether polyamide layer (B) A multilayer film comprising two extruders and a feed block that is laminated in the order of (B) layer / (A) layer / (B) layer, using the polyether polyamides b1 to b4 that form the film as shown in Table 1. Using an extruder, an unstretched multilayer film having a thickness of 90/45/90 μm and a total thickness of 225 μm was formed.
The unstretched multilayer film is stretched 3 times in length and 3 times in a batch type simultaneous biaxial stretching machine, heat-set at 210 ° C., and each layer has a thickness of 10/5/10 μm and a total thickness of 25 μm. A stretched multilayer film was obtained.
The obtained multilayer film was evaluated as described above, and the results are shown in Table 1.

[Comparative Example 1]
In Reference Example 1, the stretched multilayer was carried out in the same manner except that nylon 6 (manufactured by Ube Industries, trade name: “UBE nylon 1024B”) was used as the (B) layer instead of the polyether polyamide layer (B). A film was obtained.
The obtained multilayer film was evaluated as described above, and the results are shown in Table 1.

In Examples 2 and 3 and Reference Examples 1 and 4 , pinholes and delamination did not occur, and multilayer films having excellent oxygen barrier properties were obtained. From this, it can be seen that by forming a multilayer structure having a polyamide layer and a polyether polyamide layer, a multilayer structure having excellent pinhole resistance, oxygen barrier properties and interlayer adhesion strength is obtained.
Further, from the oxygen barrier property of Comparative Example 1, in the case of a multilayer structure with nylon 6, it can be seen that the MXD6 layer requires a certain thickness or more, but the multilayers of Examples 2, 3 and Reference Examples 1 , 4 If it is a film, it turns out that a higher oxygen barrier property is shown with the thickness of the same MXD6 layer as Comparative Example 1. Furthermore, although the multilayer film of Comparative Example 1 did not have an adhesive layer, delamination occurred, but the multilayer films of Examples 2, 3 and Reference Examples 1 and 4 did not delaminate even without an adhesive layer. It can be seen that the adhesion strength is excellent.

  The multilayer structure of the present invention has excellent pinhole resistance, oxygen barrier properties, and interlayer adhesion strength, and is therefore suitable as a sheet and film used as food packaging materials such as pouches, squeezed containers, casings, and pillow packaging. It is.

Claims (7)

A multilayer structure comprising a polyamide layer (A) and a polyether polyamide layer (B),
The said polyamide layer (A) consists of a structural unit from which a diamine structural unit derives from xylylenediamine (a-1), and a dicarboxylic acid structural unit is C4-C20 alpha, omega-linear aliphatic dicarboxylic acid ( consists polyamide consisting of structural units derived from a-2) (a),
The polyamide component of the polyether polyamide layer (B) is composed of a diamine structural unit and a dicarboxylic acid structural unit, and the diamine structural unit is represented by the following general formula (1) and a polyetherdiamine compound (b-1) and xylylene diene consists constitutional unit derived from the amine (b-2), the dicarboxylic acid constitutional unit is a polyether polyamide composed of a constitutional unit derived from adipic acid (b), in the diamine constitutional unit of the polyether polyamide (b) The multilayer structure whose ratio of the structural unit derived from a polyetherdiamine compound (b-1) is 1-8 mol% .

(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 ) —. The multilayer structure according to claim 1 , wherein the xylylenediamine (b-2) is metaxylylenediamine, paraxylylenediamine, or a mixture thereof. The multilayer structure according to claim 1 or 2 , wherein the polyamide (a) is polymetaxylylene adipamide. The multilayer structure according to any one of claims 1 to 3 , wherein the polyamide layer (A) and the polyether polyamide layer (B) each have one layer or two or more layers. The multilayer structure according to any one of claims 1 to 4 , which has at least a layer structure in the order of a polyether polyamide layer (B), a polyamide layer (A), and a polyether polyamide layer (B). The multilayer structure according to any one of claims 1 to 5 , wherein the polyamide layer (A) has a thickness of 1 to 200 µm. The multilayer structure according to any one of claims 1 to 6 , which is a sheet or a film.