JP5310902B2 - Thermoformable multilayer structure - Google Patents

Description

  The present invention relates to a multilayer structure excellent in secondary workability such as gas barrier properties and thermoforming. More specifically, the present invention relates to a multilayer structure having improved gas barrier properties and thermoformability while maintaining the excellent strength, flexibility and transparency of polyamide.

Packaging materials used for packaging foods and beverages are not only for functions such as strength, resistance to breakage, and heat resistance, but also for contents to protect the contents from various distributions, storage in refrigerators, heat sterilization, etc. A wide variety of functions are required, such as excellent transparency that enables visual recognition. Furthermore, in recent years, oxygen barrier properties that prevent the entry of oxygen from the outside in order to suppress oxidation of foods, and barrier properties with respect to various aroma components are also required with changes in taste.

Films made of olefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, and polyamides are not only transparent and excellent in mechanical properties, but are also widely used as packaging material films because of their ease of handling.

Among the above-mentioned packaging materials, crystalline aliphatic nylon represented by copolymer nylon such as nylon 6 and nylon 6/66, etc. makes use of excellent transparency and strength, and other than packaging bags such as flat bags and standing pouches. It is widely used for thermoforming containers such as blister packs. However, crystalline aliphatic nylon has the property that the crystallization speed is very fast, so there is a restriction on the drawing ratio in the field of thermoformed containers, and there are places where the thickness of the molded containers is extremely thin. There were some problems such as insufficient strength as a container.

As a conventional technique for solving these problems, polymetaxylylene adipamide (hereinafter sometimes abbreviated as N-MXD6) is added to nylon 6 at 15 to 80% by weight, for example, to delay the crystallization rate of nylon 6. Techniques are disclosed (for example, see Patent Documents 1 to 5). However, in some cases, the crystallization rate of N-MXD6 is not sufficiently slow, so that it is necessary to add a lot of N-MXD6. As a result, the transparency of the packaging container is impaired, or N-MXD6 having high rigidity The properties of MXD6 are strongly influenced, and there are cases where problems such as deterioration of the flexibility of the container occur.
Japanese Patent Laid-Open No. 1-1141737 Japanese Patent Laid-Open No. 4-120168 Japanese Unexamined Patent Publication No. 4-198329 JP-A-5-193081 Japanese Unexamined Patent Publication No. 7-117198

The object of the present invention is to overcome the problems of the prior art as described above, and to provide a multilayer structure excellent in secondary workability such as gas barrier property and deep drawing as well as excellent in transparency and mechanical properties. It is to provide.

As a result of intensive studies to overcome the problems in the prior art, the present inventors blended polyamide whose crystallization rate was delayed more than before while using a diamine component containing 70% by mole or more of metaxylylenediamine as a raw material. As a result, the present inventors have found that the secondary workability such as gas barrier property and thermoforming can be improved without impairing the characteristics of crystalline aliphatic nylon.

That is, the present invention is obtained by polycondensation of 70 to 90% by weight of crystalline polyamide (A), a diamine component containing 70% by mole or more of metaxylylenediamine and a dicarboxylic acid component, and (1) at 23 ° C. and 50 RH. The oxygen permeability coefficient is 3 ml · mm / m ² · MPa · day or less, and (2) the crystallization exothermic peak temperature observed during temperature rise measurement using a differential scanning calorimeter is observed to be 160 ° C. or higher and lower than the melting point. In other words, the present invention relates to an easily thermoformable multilayer structure in which one or more polyamide layers mainly composed of a polyamide resin composition composed of 30 to 10% by weight of polyamide (B) in which no crystallization exothermic peak is observed are laminated.

In addition to the transparency and flexibility of crystalline aliphatic nylon, the multilayer structure of the present invention is provided with oxygen barrier properties and secondary processability during deep drawing, which expands the shape range of packaging containers and allows freedom of design. The degree is expanded.

The crystalline polyamide (A) used in the present invention is a polyamide having crystallinity, and among them, an aliphatic polyamide having flexibility, strength and transparency suitable as a packaging material is preferable. Examples of the aliphatic polyamide include nylon 6, nylon 66, nylon 6/66, and the like. In order for the crystalline polyamide (A) to exhibit an appropriate function as a material constituting the packaging container, it is preferable to use a material having a sufficiently high degree of polymerization. As an index indicating the degree of polymerization, a relative viscosity (a value obtained by dissolving 1 g of polyamide in 100 ml of 96% sulfuric acid and measuring at 25 ° C.) is widely used. In the present invention, the relative viscosity of the crystalline polyamide (A) is 2 0.5 to 5.0 is preferable, and 3.0 to 4.5 is more preferable. By using the crystalline polyamide (A) having a relative viscosity within this range, the composition with the polyamide (B) is excellent in transparency, appearance, and mechanical properties, and can secure the melt processing stability.

The polyamide (B) used in the present invention is a polyamide obtained by polycondensation of a diamine component mainly composed of metaxylylenediamine and a dicarboxylic acid component.

The diamine component constituting the polyamide (B) needs to contain 70 mol% or more of metaxylylenediamine, more preferably 80 mol% or more, and still more preferably 90 mol% or more. When the metaxylylenediamine in the diamine component is 70 mol% or more, the polyamide obtained therefrom can exhibit excellent gas barrier properties. Examples of diamines that can be used in addition to metaxylylenediamine include paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, tetramethylenediamine, hexamethylenediamine, and nonamethylenediamine. , 2-methyl-1,5-pentanamine and the like, but are not limited thereto.

As the dicarboxylic acid component constituting the polyamide (B), it is preferable to use a dicarboxylic acid having 4 to 20 carbon atoms as a main component. Examples of the dicarboxylic acid having 4 to 20 carbon atoms include α, ω-linear aliphatic dicarboxylic acid, isophthalic acid, terephthalic acid such as adipic acid, suberic acid, azelaic acid, sebacic acid, and 1,10-decanedicarboxylic acid. Examples include aromatic dicarboxylic acids such as naphthalenedicarboxylic acid and alicyclic dicarboxylic acids obtained by hydrogenation thereof, but are not limited thereto. By using these dicarboxylic acids as raw materials, a polyamide having crystallinity and gas barrier properties suitable for the present invention can be obtained. As the dicarboxylic acid component, a single component may be used, or two or more types may be mixed and used, but in order to achieve both a crystallization rate delay and a gas barrier property, the dicarboxylic acid component has 4 to 20 carbon atoms. It is preferable to use an α, ω-linear aliphatic dicarboxylic acid in combination with an aromatic and / or alicyclic dicarboxylic acid having 8 to 20 carbon atoms. Preferred ratios of these are 70 to 97 mol% of α, ω-linear aliphatic dicarboxylic acid and 30 to 3 mol% of aromatic and / or alicyclic dicarboxylic acid, more preferably α, ω- The linear aliphatic dicarboxylic acid is 80 to 95 mol%, and the aromatic and / or alicyclic dicarboxylic acid is 20 to 5 mol%.

In order for the polyamide (B) to exhibit an appropriate function as a material constituting the packaging container, it is preferable to use a material having a sufficiently high degree of polymerization. In the present invention, the relative viscosity of the polyamide (B) is preferably 1.6 to 4.2, and more preferably 1.8 to 3.7. By using the polyamide (B) having a relative viscosity within this range, the composition with the crystalline polyamide (A) is excellent in transparency, appearance, and mechanical properties, and can secure the melt processing stability.

The polyamide (B) has a role of improving secondary workability such as thermoforming by enhancing the gas barrier performance of the crystalline polyamide (A) and controlling the crystallization speed. Therefore, the polyamide (B) needs to satisfy the following (1) and (2) simultaneously.
(1) Oxygen permeability coefficient at 23 ° C. and 50 RH is 3 ml · mm / m ² · MPa · day or less (2) Peak temperature of crystallization exotherm observed during temperature rise measurement using a differential scanning calorimeter (DSC) Is observed below 160 ° C. to below the melting point or no crystallization exothermic peak is observed

The oxygen permeability coefficient of polyamide (B) at 23 ° C. and 50 RH needs to be 3 ml · mm / m ² · MPa · day or less, more preferably 2 ml · mm / m ² · MPa · day or less, and even more preferably Is 1 ml · mm / m ² · MPa · day or less. When it is 3 ml · mm / m ² · MPa · day or less, the effect of improving the oxygen barrier performance by blending the polyamide (B) can be effectively obtained.

Further, the slower the crystallization rate of the polyamide (B), the better the effect of controlling the crystallization rate of the crystalline polyamide (A) can be obtained by adding a small amount of the polyamide (B), which is economical and the moldability is easily stabilized. . As a measure of the crystallization rate of the polyamide (B), a crystallization exothermic peak temperature (hereinafter sometimes abbreviated as Tch) observed by measurement using a differential scanning calorimeter (DSC) is used. In the present invention, the DSC Tch measurement method is as follows.
(1) A polyamide (B) sample is melted at a heating rate of 10 ° C./min under a nitrogen stream.
(2) Rapidly cool the polyamide (B) sample immediately after the temperature rise using liquid nitrogen or dry ice.
(3) The rapidly cooled polyamide (B) sample is melted at a temperature rising rate of 10 ° C./min from room temperature under a nitrogen stream, and the peak of the exothermic peak derived from crystallization is defined as Tch.

  The polyamide (B) must have a Tch of 160 ° C. or higher and lower than the melting point or a crystallization exothermic peak is not observed, and more preferably Tch is observed at 160 ° C. or higher and lower than the melting point. More preferably, it is observed at 163 ° C. or higher and lower than the melting point. When a crystallization exothermic peak temperature is observed below 160 ° C., it may be necessary to add a large amount of polyamide (B) in order to sufficiently obtain the crystallization rate control effect of the crystalline polyamide (A). Further, it is not preferable because molding processability may change or appearance such as transparency may deteriorate.

The multilayer structure of the present invention is obtained by laminating one or more polyamide layers mainly composed of a polyamide resin composition composed of crystalline polyamide (A) and polyamide (B). The blending ratio of the crystalline polyamide (A) and the polyamide (B) in the polyamide layer is 70 to 90% by weight for the crystalline polyamide (A) and 30 to 10% by weight for the polyamide (B) (crystalline polyamide (A). And polyamide (B) is 100% by weight in total, preferably 25 to 10% by weight of polyamide (B), more preferably 20 to 10% by weight of polyamide (B). By forming the polyamide layer within the above-mentioned range, it is possible to improve the secondary workability such as effective gas barrier property and thermoforming while maintaining the excellent physical properties of the crystalline polyamide (A), and more stable melt extrusion processing Sexuality is possible.

The polyamide layer in the present invention retains the excellent physical properties of the crystalline polyamide (A) while improving the physical properties by the polyamide (B). For example, the tensile modulus of the polyamide layer made of crystalline polyamide (A) and polyamide (B) is preferably 1 GPa or less, more preferably 0.95 GPa or less, and still more preferably 0.9 GPa or less. It is preferable that the tensile elastic modulus is in the above-mentioned range since the flexibility and impact resistance performance that are characteristic of the crystalline polyamide (A) are not impaired.

In order to form a polyamide layer that sufficiently exhibits the gas barrier properties of the polyamide (B) and the effect of suppressing the crystallization rate of the crystalline polyamide (A), the polyamide layer preferably has a sea-island structure. More preferably, the polyamide (B) is finely dispersed in the layer.
The dispersed particle diameter of the polyamide (B) in the polyamide layer is preferably 95% or more with a major axis of 1 micron or less, more preferably 98% or more. The dispersion state of the polyamide (B) can be observed with an electron microscope (TEM, SEM, etc.). When the dispersed particle diameter of the polyamide (B) is within the above range, the properties of the polyamide (B) can be imparted without impairing the excellent physical properties of the crystalline polyamide (A).

In order to disperse the polyamide (B) as described above, a method of devising a melt mixing method of the crystalline polyamide (A) and the polyamide (B) using an extruder, a method of adjusting the melt viscosity of both, and the like can be mentioned. . Examples of the melt mixing method include conventionally known methods, for example, a method using a single screw extruder or a twin screw extruder, and these can be applied. When a single screw extruder is used, such as a dull image. It is preferable to use a single screw extruder equipped with a screw having a kneading part. As a method for reducing the dispersed particle size of the polyamide (B) in the polyamide layer, the melt viscosity of the crystalline polyamide (A) and the polyamide (B) at a shear rate of 100 s ^-1 at the molding temperature when forming the polyamide layer. A method in which the ratio (crystalline polyamide (A) / polyamide (B)) is 1.2 or more is preferably used, more preferably 1.5 or more, and even more preferably 1.8 or more. By setting the melt viscosity of the island portion constituting the sea-island structure low, it is preferable because the shear stress generated at the time of melt processing works effectively to finely disperse. It is preferable to set the melt viscosity ratio as described above because, for example, even a single-screw extruder that does not have a kneading site such as a full flight screw can easily control the dispersion state of the polyamide (B).

Further, in order to obtain an effective physical property improving effect by adding the polyamide (B), it is preferable to make the melt mixing conditions of the crystalline polyamide (A) and the polyamide (B) appropriate. For example, the extruder temperature setting at the time of melt mixing is preferably set to less than 300 ° C, more preferably 290 ° C or less, and further preferably 280 ° C or less. If the temperature is set higher than 300 ° C., the amide exchange reaction occurs at the time of the melt mixing of the crystalline polyamide (A) and the polyamide (B), so that they become compatible, and the crystalline polyamide (A) and the polyamide (B ), And the excellent physical properties of each polyamide may be lost. As a method for confirming that such a phenomenon is prevented, there is a method for confirming the melting point of each material by DSC of the molten mixture. In the present invention, the melting point derived from the crystalline polyamide (A) observed when the temperature of the polyamide layer is measured using DSC is within ± 5 ° C. from the melting point of the crystalline polyamide (A) alone. Is preferable, more preferably ± 4 ° C, and further preferably ± 3 ° C. If the deviation from the melting point of the crystalline polyamide (A) is within ± 5 ° C., there is almost no compatibilization, the sea-island structure of the crystalline polyamide (A) and the polyamide (B) is maintained, and both are excellent. The physical properties can be utilized.
As a matter of course, the crystalline polyamide (A) and the polyamide (B) need to be melt-processable at 300 ° C. or lower.

  The polyamide (crystalline polyamide (A), polyamide (B)) used in the present invention may be crystallized and whitened due to water absorption in some cases, thereby impairing the appearance of the multilayer container. In order to prevent such a phenomenon, it is preferable to add a specific fatty acid metal salt, diamide compound or diester compound as an anti-whitening agent to the polyamide in the present invention.

  The fatty acid metal salt used in the present invention is a fatty acid metal salt having 18 to 50 carbon atoms, preferably 18 to 34 carbon atoms. If the carbon number is 18 or more, whitening when the polyamide absorbs water can be prevented. Moreover, carbon number is 50 or less, and uniform dispersion | distribution in a resin composition becomes favorable. Fatty acids may have side chains or double bonds, but linear saturated such as stearic acid (C18), eicoic acid (C20), behenic acid (C22), montanic acid (C28), triacontanoic acid (C30) Fatty acids are preferred. The metal that forms a salt with the fatty acid is not particularly limited, but sodium, potassium, lithium, calcium, barium, magnesium, strontium, aluminum, zinc, etc. are exemplified, and sodium, potassium, lithium, calcium, aluminum, and zinc are particularly preferable.

  One type of fatty acid metal salt used in the present invention may be used, or two or more types may be used in combination. In the present invention, the shape of the fatty acid metal salt is not particularly limited. However, the smaller the particle size, the easier it can be uniformly dispersed in the resin composition, and therefore the particle size is preferably 0.2 mm or less.

The diamide compound used in the present invention is a diamide compound obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms. The effect of preventing whitening can be expected when the fatty acid has 8 or more carbon atoms and the diamine has 2 or more carbon atoms. Moreover, the carbon number of the fatty acid is 30 or less and the carbon number of the diamine is 10 or less, so that uniform dispersion in the composition is good.

  The fatty acid used in the diamide compound may have a side chain or a double bond, but is preferably a linear saturated fatty acid. Examples include stearic acid (C18), eicoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanoic acid (C30). Of these, montanic acid is preferred. Examples of the diamine used in the diamide compound include ethylenediamine, butylenediamine, hexanediamine, xylylenediamine, bis (aminomethyl) cyclohexane, and the like. Among them, compounds having ethylenediamine in the skeleton are preferable. These may be used alone or in combination of two or more.

  The diester compound used in the present invention is a diester compound obtained from a fatty acid having 8 to 30 carbon atoms and a diol having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diol has 2 or more carbon atoms, a whitening prevention effect can be expected. Further, when the fatty acid has 30 or less carbon atoms and the diol has 10 or less carbon atoms, uniform dispersion in the composition becomes good.

  Examples of fatty acids used in the diester compound include stearic acid (C18), eicoic acid (C20), behenic acid (C22), montanic acid (C28), triacontanoic acid (C30), and among them, montanic acid is preferable. Examples of the diol used in the diester compound include ethylene glycol, propanediol, butanediol, hexanediol, xylylene glycol, and cyclohexanedimethanol, and ethylene glycol or 1,3-butanediol is particularly preferable. A diester compound obtained by combining these is used in the present invention. One type of diester compound may be used, or two or more types may be used in combination.

The diamide compound and diester compound used in the present invention may be used alone or in combination.
In the present invention, the addition amount of the diamide compound and / or diester compound is 0.005 to 1.0 part by weight, preferably 0.05 to 0.5 part by weight, particularly preferably 0.005 part by weight based on 100 parts by weight of the polyamide. 12 to 0.5 parts by weight. When the addition amount of the diamide compound and / or diester compound is less than 0.005 parts by weight, a practical whitening prevention effect cannot be obtained. On the other hand, when the amount is more than 1.0 part by weight, the polyamide becomes white due to the influence of the diamide compound and / or diester compound, which is not preferable.

  A known mixing method can be applied to the method of adding the whitening inhibitor to the polyamide. For example, polyamide pellets and a whitening inhibitor may be charged and mixed in a rotating hollow container. In addition, after manufacturing a composition containing a high concentration whitening inhibitor, a method of diluting the polyamide pellets containing no whitening inhibitor at a predetermined concentration and then melt-kneading them, followed by melt-kneading, injection molding, etc. For example, a method of obtaining a molded body by the method is adopted.

  The polyamide resin composition of the present invention includes impact modifiers such as various elastomers, copper compounds, organic or inorganic halogen compounds, hindered phenol compounds, and organic phosphorus compounds within a range that does not impair the effects of the present invention. Additives such as antioxidants such as compounds, heat stabilizers, anti-coloring agents, UV absorbers such as benzotriazoles, mold release agents, plasticizers, coloring agents, and flame retardants may be included.

The polyamide resin composition can be used after being processed into a layer constituting a molded body such as various packaging materials and packaging containers. The packaging material can be processed into a film-like or sheet-like molded body, and the packaging container constitutes at least a part of bottles, trays, cups, tubes, various pouches such as flat bags and standing pouches, etc. Can be used as a material. Further, the packaging material or the packaging container may have a single layer made of the polyamide resin composition obtained in the present invention or a multilayer structure combined with other thermoplastic resins.

A well-known method can be utilized about the manufacturing method of the packaging material and packaging container which utilize the said polyamide resin composition. For example, the film, sheet, or tube-shaped packaging material can be molded by extrusion from an extruder to which the polyamide melted through a T die, a circular die or the like is attached. In addition, the film-shaped molded object obtained by said method can also be processed into a stretched film by extending | stretching this.
The packaging material and packaging container using the polyamide resin molded product of the present invention can be manufactured through various methods regardless of the above-described manufacturing method.

The multilayer structure of the present invention can be obtained, for example, by laminating the polyamide layer and a polyolefin layer such as polyethylene or polypropylene by coextrusion using an adhesive resin, or by laminating by various lamination processes. The polyolefin layer preferably forms the outermost layer and the innermost layer of the multilayer structure. Examples of the layer structure include, but are not limited to, three layers and five layers of polyolefin layer / adhesive resin layer / polyamide layer / adhesive resin layer / polyolefin layer.

The multilayer structure of the present invention can be laminated with various thermoplastic resin layers and metal films such as aluminum foil in addition to the polyolefin layer, the adhesive resin layer, and the polyamide layer as necessary. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate and aliphatic polyamides such as nylon 6. In addition, the trimming waste produced by trimming the multilayer film / sheet and multilayer container is pulverized, and the pulverized product alone or mixed with polyolefin or other thermoplastic resin is used as a recycled resin layer to adhere to the polyolefin layer. It can laminate | stack as an intermediate | middle layer between resin layers. Moreover, in order to give a characteristic to a multilayer container, the thermoplastic resin layer which consists of a polycarbonate and various easy-peeling resin can be laminated | stacked on the front side of a polyolefin layer. Not limited to these, various thermoplastic resin layers can be laminated according to the purpose. Furthermore, the multilayer structure of the present invention can be subjected to special processing for imparting an easy peel function to the flange portion or processing such as vapor deposition of an inorganic oxide thin film layer.

By using the multilayer structure of the present invention, various packaging containers can be produced. Various items can be stored and stored in the packaging container. For example, carbonated drinks, juice, water, milk, sake, whiskey, shochu, coffee, tea, jelly drinks, health drinks and other liquid drinks, seasoning liquids, sauces, soy sauce, dressings, liquid dashi, mayonnaise, miso, and savory spices Seasonings such as jams, creams, chocolate pastes and other paste-like foods, liquid soups, boiled foods, pickles, stewed and other liquid processed foods such as buckwheat noodles, noodles, ramen and other raw noodles and boiled noodles , Rice before cooking such as polished rice, moisture-conditioned rice, wash-free rice, etc., cooked cooked rice, processed rice products such as gomoku rice, red rice, rice bran, powdered seasonings such as powdered soup, dashi stock, jelly, High-moisture foods such as pudding, dried vegetables, coffee beans, coffee powder, tea, low-moisture foods such as confectionery made from grains, and other solids and solutions such as agricultural chemicals and insecticides Chemicals, liquid and pasty medicines, lotions, makeup creams, cosmetic milky lotion, hair dressing, it is possible to house a hair dye, shampoo, soap, detergent or the like, various articles.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples. In this example, various measurements were performed by the following methods.

(1) Tensile modulus (MPa)
A single-layer film having a thickness of 20 μm was produced, and the tensile modulus was measured according to ASTM D882. As a measuring device, a measuring device (Strograph V1-C) manufactured by Toyo Seiki Seisakusho Co., Ltd. was used.
(2) Oxygen transmission coefficient (ml · mm / m ² · MPa · day)
A single-layer film having a thickness of 20 μm was used. Using OX-TRAN2 / 21 manufactured by Modern Controls, measurement was performed under the conditions of 23 ° C. and relative humidity of 50% RH.
(3) Evaluation of thermoformability Using a multilayer film having a layer structure of LLDPE layer / adhesive resin layer / polyamide layer / adhesive resin layer / LLDPE layer = 50/10/20/10/50 (micron), plug Using a vacuum / pressure forming machine with assistance (Pressure / air forming machine manufactured by Asano Laboratories), thermoforming a multilayer sheet under the condition of a surface temperature of 90 ° C., caliber 62 mm × bottom diameter 52 mm × depth 28 mm, surface area 73 cm ^2. A cup-shaped container having a volume of 70 ml was obtained. The case where the transfer state to the mold was good was rated as “◯”, and the case where the molding such as the corner portion was poor was marked as “X”.

(4) Crystallization exothermic peak temperature Using a differential scanning calorimeter (DSC), the crystallization exothermic peak temperature (Tch) of polyamide (B) was measured by the following procedure.
(A) The polyamide (B) is melted at a heating rate of 10 ° C./min under a nitrogen stream.
(B) The polyamide (B) sample immediately after temperature rising is rapidly cooled using dry ice.
(C) The rapidly cooled polyamide (B) is melted at a temperature rising rate of 10 ° C./min from room temperature under a nitrogen stream, and the peak of the exothermic peak derived from crystallization is defined as Tch (° C.).

Production Example 1
9654 g (66.06 mol) of adipic acid and 578 g of isophthalic acid precisely weighed in a reaction vessel having an internal volume of 50 liters equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel and a nitrogen introduction tube, and a strand die ( 3.48 mol) was added, and after sufficient nitrogen substitution, the system was heated to 170 ° C. with stirring in a small amount of nitrogen stream. To this, 9044 g (66.40 mol) of metaxylylenediamine was added dropwise with stirring, and the inside of the system was continuously heated while removing the generated condensed water. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was set to 255 ° C. and the reaction was continued for 40 minutes. Thereafter, the inside of the system was pressurized with nitrogen, and the polymer was taken out from the strand die and pelletized to obtain about 16 kg of polymer.
Next, the polymer is charged into a tumble dryer with a jacket provided with a nitrogen gas inlet tube, a vacuum line, a vacuum pump, and a thermocouple for measuring the internal temperature. The purity of the tumble dryer is 99% by volume while rotating at a constant speed. After sufficiently replacing with the above nitrogen gas, the tumble dryer was heated under the same nitrogen gas stream, and the pellet temperature was raised to 150 ° C. over about 150 minutes. When the pellet temperature reached 150 ° C., the pressure in the system was reduced to 1 torr or less. The temperature was further raised, and the pellet temperature was raised to 200 ° C. over about 70 minutes, and then held at 200 ° C. for 40 minutes. Next, nitrogen gas having a purity of 99% by volume or more was introduced into the system and cooled while the tumble dryer was rotated to obtain polyamide B-1. Polyamide B-1 has a relative viscosity of 2.6, 23 ° C., an oxygen permeability coefficient at 50 RH of 0.7 ml · mm / m ² · MPa · day, and a melt viscosity at 250 ° C. at a shear rate of 100 s ⁻¹ is 969 Pa · s. Met. Moreover, Tch of polyamide B-1 was 167 degreeC.

Production Example 2
Polyamide B-2 was obtained in the same manner as in Production Example 1 except that 9185 g (62.85 mol) of adipic acid and 666 g (6.69 mol) of isophthalic acid were used. Polyamide B-2 has a relative viscosity of 2.6, 23 ° C., an oxygen transmission coefficient of 0.7 ml · mm / m ² · MPa · day at 50 RH, and a melt viscosity of 983 Pa · s at a shear rate of 100 s ⁻¹ at 250 ° C. Met. Further, Tch of polyamide B-2 was 171 ° C.

Production Example 3
Polyamide B-3 was obtained in the same manner as in Production Example 1 except that 7114 g (48.68 mol) of adipic acid and 3466 g (20.86 mol) of isophthalic acid were used. Polyamide B-3 has a relative viscosity of 2.2, 23 ° C., an oxygen permeability coefficient at 50 RH of 0.8 ml · mm / m ² · MPa · day, and a melt viscosity at 250 ° C. at a shear rate of 100 s ⁻¹ is 400 Pa · s. Met. Further, no crystallization exothermic peak was observed in the DSC measurement of polyamide B-3.

Production Example 4
Polyamide B-4 was obtained in the same manner as in Production Example 1 except that 8130 g (55.63 mol) of adipic acid was used and 2813 g (13.91 mol) of sebacic acid was used instead of isophthalic acid. Polyamide B-4 has a relative viscosity of 2.1, 23 ° C., an oxygen transmission coefficient at 50 RH of 1.5 ml · mm / m ² · MPa · day, and a melt viscosity at 250 ° C. and a shear rate of 100 s ⁻¹ is 355 Pa · s. Met. Moreover, Tch of polyamide B-4 was 170 ° C.

Production Example 5
Polyamide B-5 was obtained in the same manner as in Production Example 1 except that only 10163 g (69.54 mol) of adipic acid was used as the dicarboxylic acid. Polyamide B-5 has a relative viscosity of 2.6, 23 ° C., an oxygen permeability coefficient at 50 RH of 1.0 ml · mm / m ² · MPa · day, and a melt viscosity at 250 ° C. at a shear rate of 100 s ⁻¹ at 936 Pa · s. Met. Further, Tch of polyamide B-5 was 155 ° C.

Production Example 6
Polyamide B-6 was obtained in the same manner as in Production Example 1 except that 9959 g (68.15 mol) of adipic acid and 231 g (1.39 mol) of isophthalic acid were used. Polyamide B-6 has a relative viscosity of 2.6, 23 ° C., an oxygen transmission coefficient of 0.9 ml · mm / m ² · MPa · day at 50 RH, and a melt viscosity of 940 Pa · s at a shear rate of 100 s ⁻¹ at 250 ° C. Met. Moreover, Tch of polyamide B-6 was 158 ° C.

Production Example 7
Polyamide B-7 was obtained in the same manner as in Production Example 1 except that only 14064 g (69.54 mol) of sebacic acid was used as the dicarboxylic acid. Polyamide B-7 has a relative viscosity of 2.1, 23 ° C., an oxygen transmission coefficient of 15.0 ml · mm / m ² · MPa · day at 50 RH, and a melt viscosity of 364 Pa · s at a shear rate of 100 s ⁻¹ at 250 ° C. Met. Further, no crystallization exothermic peak was observed in the DSC measurement of polyamide B-7.

Reference example 1
Polyamide B-1, nylon 6 (manufactured by Ube Industries, Ltd., trade name: UBE nylon, grade: 1024B, relative viscosity: 3.4, melt viscosity at 250 ° C. with shear rate of 100 s ⁻¹ : 947 Pa · s , Hereinafter referred to as “polyamide A-1”) was dry blended at a weight ratio of 90/10 (polyamide A-1 / polyamide B-1) to obtain a mixed polyamide. The mixed polyamide is supplied to a single-layer sheet molding machine (PTM-30 manufactured by Plastics Engineering Laboratory) equipped with a 30 mmφ twin-screw extruder, a T die, a cooling roll, and a winder, screw rotation 100 rpm, extrusion temperature 250 A single layer film having a thickness of 20 μm was obtained at a temperature of 1.5 ° C. and a take-off speed of 1.5 m / min.
In addition, a multi-layer sheet manufacturing apparatus equipped with three 40 mmφ single-screw extruders, a feed block, a T die, a cooling roll, a winder, and the like was used. Co., Ltd., trade name: Novatec LL, grade: UF340) at 240 ° C. Adhesive resin (Mitsubishi Chemical Co., Ltd., trade name: Modic AP, grade) with screw rotation of 29 rpm from the second extruder : L504) at 230 ° C., the mixed polyamide is extruded at 250 ° C. from the third extruder at a screw rotation of 11 rpm, and LLDPE layer / adhesive resin layer / mixed polyamide layer / adhesive resin through a feed block. A multilayer sheet having a 3 layers / 5 layers structure of layer / LLDPE layer was obtained at a take-up speed of 2.5 m / min. The cooling roll temperature was 20 ° C. The thickness of each layer was 50/10/20/10/50 (μm).
The tensile modulus and oxygen transmission coefficient were measured for the single layer film. Moreover, the thermoformability was evaluated about the multilayer sheet. The results are shown in Table 1.

Reference example 2
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 1 except that Polyamide A-1 / Polyamide B-1 was changed to 80/20. The evaluation results are shown in Table 1.

Reference example 3
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide A-1 / polyamide B-1 was changed to 70/30. The evaluation results are shown in Table 1.

Example 4
Nylon 6 instead of polyamide A-1 (manufactured by Ube Industries, Ltd., trade name: UBE nylon, grade: 1030B, relative viscosity: 4.1, melt viscosity at shear rate of 100 s- ¹ at 250 ° C .: 1649 Pa · s Hereinafter referred to as “polyamide A-2”), and a single layer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide B-2 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

Example 5
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 2 except that polyamide A-2 was used instead of polyamide A-1 and polyamide B-2 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

Example 6
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 3 except that polyamide A-2 was used instead of polyamide A-1 and polyamide B-2 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

Example 7
A single layer film and a multilayer sheet were obtained in the same manner as in Example 4 except that polyamide B-3 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Example 8
A single layer film and a multilayer sheet were obtained in the same manner as in Example 5 except that polyamide B-3 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Example 9
A single layer film and a multilayer sheet were obtained in the same manner as in Example 6 except that polyamide B-3 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Example 10
A single layer film and a multilayer sheet were obtained in the same manner as in Example 4 except that polyamide B-4 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Example 11
A single layer film and a multilayer sheet were obtained in the same manner as in Example 5 except that polyamide B-4 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Example 12
A single layer film and a multilayer sheet were obtained in the same manner as in Example 6 except that polyamide B-4 was used instead of polyamide B-2. The evaluation results are shown in Table 1.

Comparative Example 1
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 1 except that the polyamide A-1 / polyamide B-1 was changed to 95/5. The evaluation results are shown in Table 1.

Comparative Example 2
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide A-1 / polyamide B-1 was changed to 65/35. The evaluation results are shown in Table 1.

Comparative Example 3
A single layer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide B-5 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

Comparative Example 4
A single layer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide B-6 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

Comparative Example 5
A monolayer film and a multilayer sheet were obtained in the same manner as in Example 1 except that polyamide B-7 was used instead of polyamide B-1. The evaluation results are shown in Table 1.

The multilayer structure of the present invention has excellent gas barrier properties as well as excellent transparency and flexibility, and is very useful as a packaging material for foods, beverages, medicines, electronic parts and the like. , Its industrial value is very high.

Claims (7)

Obtained by polycondensation of 70 to 90% by weight of crystalline polyamide (A) with a diamine component containing 70% by mole or more of metaxylylenediamine and a dicarboxylic acid component, and (1) an oxygen transmission coefficient of 3 ml at 23 ° C. and 50 RH · Mm / m ² · MPa · day or less, and (2) a crystallization exothermic peak temperature observed at a temperature rise measurement using a differential scanning calorimeter is observed from 160 ° C to less than the melting point, or crystallization exotherm. A thermoformable multilayer structure in which one or more polyamide layers composed mainly of a polyamide resin composition consisting of 30 to 10% by weight of polyamide (B) in which no peak is observed, and having a shear rate of 100 / second, 250 Multilayer structure in which the melt viscosity ratio (polyamide (A) / polyamide (B)) of the crystalline polyamide (A) and the polyamide (B) under the condition of ° C is 1.2 to 4.6 body. The easily thermoformable multilayer structure according to claim 1, wherein the dicarboxylic acid component constituting the polyamide (B) is a dicarboxylic acid having 4 to 20 carbon atoms. The dicarboxylic acid component constituting the polyamide (B) is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and an aromatic and / or alicyclic dicarboxylic acid 30 having 8 to 20 carbon atoms. The easily thermoformable multilayer structure according to claim 1 or 2, comprising -3 mol%. The easily thermoformable multilayer structure according to any one of claims 1 to 3, wherein the crystalline polyamide (A) is an aliphatic polyamide. The easily thermoformable multilayer structure according to any one of claims 1 to 4, wherein the crystalline polyamide (A) is nylon 6. The easily thermoformable multilayer structure according to any one of claims 1 to 5, wherein the polyamide layer has a tensile elastic modulus of 1 GPa or less. A packaging container using at least a part of the thermoformable multilayer structure according to claim 1.