JP5659626B2 - Biaxially stretched film - Google Patents

Description

  The present invention relates to a biaxially stretched film, and more particularly to a biaxially stretched film having excellent barrier properties under high humidity.

  Conventionally, a metal can, a glass bottle, or a container or a molded body made of a thermoplastic resin has been used as a packaging material for pharmaceuticals, beverages, foods, chemicals, and the like. Among these, containers and molded bodies made of thermoplastic resins are superior in terms of light weight, moldability, packaging productivity such as heat sealing, and cost, and are used in the largest quantities. However, containers and molded bodies made of thermoplastic resin are generally excellent as packaging materials, but oxygen permeation through the container wall occurs in an order that cannot be ignored, and there remains a problem in terms of storage stability of contents. .

  In order to prevent oxygen permeation from outside the container, the container wall or molded body of the thermoplastic resin has a multilayered container wall, and at least one of them has polymetaxylylene adipamide (hereinafter referred to as “N-MXD6”). ), An ethylene-vinyl alcohol copolymer (hereinafter referred to as “EVOH”), a gas barrier resin such as polyacrylonitrile, an aluminum foil, or the like is provided as an oxygen barrier layer. However, a film in which N-MXD6 or vinylidene chloride is laminated has a relatively good gas barrier property regardless of the storage conditions, but has not yet exhibited a sufficient gas barrier property. Furthermore, vinylidene chloride has a problem that dioxins are generated when it is burned and pollutes the environment. Although EVOH and polyvinyl alcohol do not have the problem of environmental pollution as described above, multilayer films using these as barrier layers exhibit excellent gas barrier properties when stored in a relatively low humidity environment. The gas barrier properties are greatly reduced if the contents are highly water-active or stored in a high-humidity environment, or if the contents are filled and then subjected to heat sterilization such as so-called boil treatment or retort treatment. There has been a problem that the amount of oxygen permeating through the contents increases, causing problems in the storage stability of the contents.

  In addition, these gas barrier resins have been conventionally subjected to biaxial stretching. Although a multilayer biaxially stretched film composed of N-MXD6 and nylon 6 (hereinafter referred to as “N-6”) has been conventionally used in film packaging containers such as pouches, depending on the storage environment and contents, It has not reached a sufficient barrier property. In addition, vinylidene chloride is used by being coated on another resin, but cracks and the like are generated when it is stretched, so that sufficient performance has not been achieved. In addition, since EVOH has a high crystallization speed, there is a problem in that stretched film is not stretched uniformly during stretched film production, causing stretch spots, and frequent film breakage. Manufacturing was difficult. In order to solve this problem, an EVOH unstretched film having a specific density is adjusted to a moisture content of 3.5% by weight or less and stretched at 50 to 130 ° C. (Patent Document 1), an extruder and a T die. There is a method (Patent Document 2) for controlling the temperature by providing a heat exchanger between the two.

Japanese Patent Publication No. 60-26697 JP-A-11-254523

However, in any of the above methods, the stretched film in the EVOH single layer still causes film breakage during stretching and is difficult to produce stably, or the film thickness accuracy of the stretched film is inferior, Desired physical properties may not be obtained. Furthermore, the deterioration of barrier properties under high humidity, which is a weak point of EVOH, still cannot be solved.

The present invention has been made in view of such circumstances, and the problem is that a biaxially stretched film is easy to biaxially stretch and exhibits excellent oxygen barrier properties not only under low humidity conditions but also under high humidity conditions. Is to provide.

The present invention provides the following biaxially stretched films.
That is, it has a layer made of a polyamide resin composition consisting of 99 to 55% by mass of an ethylene vinyl alcohol copolymer and 1 to 45% by mass of a semiaromatic polyamide having a temperature decrease and crystallization time at 160 ° C. of 20 seconds or more. Axial stretched film.

  The present invention provides a biaxially stretched film that exhibits excellent oxygen barrier properties not only under low humidity conditions but also under high humidity and has good moldability.

First, EVOH, which is a raw material resin used in the present invention, will be described. In the present invention, the ethylene content is usually 10 to 60 mol%, preferably 20 to 60 mol%, more preferably 25 to 55 mol%, and the saponification degree of the vinyl acetate component is usually 90 mol% or more, preferably 95 mol% or more of EVOH is used.
If the ethylene content of EVOH is 10 mol% or more, the water resistance of the resulting film will be good. Moreover, if the saponification degree of a vinyl acetate component is 90 mol% or more, the water resistance of the obtained film will become favorable.

In particular, EVOH in which the sum of the Na and K metal contents contained in EVOH is in the range of 0.01 to 30 ppm is preferably used. More preferably, the sum of the above metal contents is 0.1 to 10 ppm.
If the sum of the above metal contents in EVOH is 0.01 ppm or more, coloring (yellowing) can be kept low during extrusion. Moreover, if this metal content is 30 ppm or less, since the generation frequency of gel can be suppressed low, generation | occurrence | production of the film fracture | rupture at the time of extending | stretching resulting from it is suppressed.
Further, the metal content other than Na and K is not particularly limited, but the inclusion of 5 to 300 ppm Ca and / or 5 to 200 ppm Mg is preferable in order to exert the effect of suppressing the generation of gel.

The EVOH used in the present invention may be variously modified as necessary, or may be a mixture of modified EVOH and unmodified EVOH. Examples of the modified EVOH include, for example, modified EVOH with propylene, isobutene, etc., modified EVOH with at least one kind of α-olefin having 3 to 30 carbon atoms or at least one ethylene of the olefin, and graft polymerization of acrylic acid ester. Modified EVOH, modified EVOH obtained by saponification of terpolymer composed of (meth) acrylic acid ester-ethylene-vinyl acetate, modified EVOH modified with EVOH hydroxyl group by cyanoethyl group, polyester and vinyl alcohol depolymerized Modified EVOH containing polyester graft product obtained by reaction, modified EVOH obtained by saponifying copolymer of vinyl acetate-ethylene-silicon-containing olefinically unsaturated monomer, pyrrolidone ring-containing monomer-ethylene- Ternary made of vinyl acetate Saponified modified EVOH obtained by saponification of the polymer, saponified modified EVOH obtained by saponification of the terpolymer of acrylamide-ethylene-vinyl acetate, and terpolymer of allyl acetate-ethylene-vinyl acetate The obtained modified EVOH, the modified EVOH obtained by saponifying the terpolymer of isopropenyl acetate-ethylene-vinyl acetate, the modified EVOH obtained by adding a polyether component to the terminal of EVOH, and the polyether component is EVOH. Examples of the modified EVOH include a modified EVOH added as a branched polymer in a graft form, and a modified EVOH in which an alkylene oxide is added to the EVOH.

The EVOH used in the present invention is a comonomer such as an α-olefin other than those described above, an unsaturated carboxylic acid or a salt thereof, a partial alkyl ester, a complete alkyl ester, a nitrile, an amide, an anhydride, an unsaturated sulfonic acid or a salt thereof. May be included.

［前記一般式（II）中、ｎは２〜１８の整数を表す。前記、一般式（III）中、Ｒは脂肪族又は脂環族の２価の基を表わす。また、前記一般式（IV）中、Ａｒはアリーレン基を表す。］ Next, the semi-aromatic polyamide used in the present invention will be described.
The semi-aromatic polyamide in the present application is a polyamide composed of a structural unit having an aromatic ring and a structural unit not having an aromatic ring, and a diamine unit containing 70 mol% or more of an aromatic diamine unit represented by the following formula (I); A polyamide (hereinafter sometimes referred to as polyamide (A)) comprising a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit represented by the following general formula (II), or the following general formula (III ) And a dicarboxylic acid unit containing 70 mol% or more of an aromatic dicarboxylic acid unit represented by the following general formula (IV) (hereinafter referred to as polyamide (hereinafter referred to as “polyamide”). B)) is preferred, and a combination of both may be used. Furthermore, the semi-aromatic polyamide used in the present invention may further contain constituent units other than the diamine units and dicarboxylic acid units as long as the effects of the present invention are not impaired. Here, the diamine unit refers to a structural unit derived from diamine, and the dicarboxylic acid unit refers to a structural unit derived from dicarboxylic acid.

[In said general formula (II), n represents the integer of 2-18. In the general formula (III), R represents an aliphatic or alicyclic divalent group. In the general formula (IV), Ar represents an arylene group. ]

  In the semi-aromatic polyamide used in the present invention, the content ratio of the diamine unit and the dicarboxylic acid unit is preferably substantially the same from the viewpoint of the polymerization reaction, and the content of the dicarboxylic acid unit (all components) More preferably, the mol% relative to the unit is ± 2 mol% of the content of the diamine unit.

(Diamine unit (I))
First, the semiaromatic polyamide (A) will be described.
The diamine unit in the semi-aromatic polyamide (A) used in the present invention provides excellent gas barrier properties, and also improves transparency and color tone, and facilitates general-purpose thermoplastic resin moldability. From the above, the aromatic diamine unit represented by the formula (I) is contained in the diamine unit in an amount of 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, and further preferably 95 mol% or more. Moreover, it is preferably 100 mol% or less.

  Examples of the compound that can constitute the aromatic diamine unit represented by the formula (I) include orthoxylylenediamine, metaxylylenediamine, and paraxylylenediamine. These can be used alone or in combination of two or more.

  The diamine unit in the semi-aromatic polyamide (A) used in the present invention is a metaxylylenediamine unit from the viewpoint of facilitating moldability of a general-purpose thermoplastic resin in addition to exhibiting excellent gas barrier properties. It is preferable to contain 70 mol% or more in a diamine unit, Preferably it is 80 mol% or more, More preferably, it is 90 mol% or more, More preferably, it is 95 mol% or more, Preferably it is 100 mol% or less.

  Examples of the compound that can constitute a diamine unit other than the aromatic diamine unit represented by the formula (I) include 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, and tetramethylenediamine. , Pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, 2-methyl-1,5-pentanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane and the like. However, it is not limited to these. These can be used alone or in combination of two or more.

(Dicarboxylic acid unit)
The dicarboxylic acid unit in the semi-aromatic polyamide (A) is a straight chain represented by the general formula (II) from the viewpoint of imparting appropriate crystallinity and imparting flexibility necessary as a packaging material. The dicarboxylic acid unit contains 70 mol% or more of the aliphatic dicarboxylic acid unit, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less. It is.

  In said general formula (II), n represents the integer of 2-18, Preferably it is 3-16, More preferably, it is 4-12, More preferably, it is 4-8. Examples of the compound that can constitute the linear aliphatic dicarboxylic acid unit represented by the general formula (II) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,10- Although decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, etc. can be illustrated, it is not limited to these. These can be used alone or in combination of two or more.

The dicarboxylic acid unit in the semi-aromatic polyamide (A) is an adipic acid unit, a sebacic acid unit, and 1,12-dodecane from the viewpoint of maintaining heat resistance after heat sterilization of the packaging material in addition to excellent gas barrier properties. It is preferable that at least one selected from the group consisting of dicarboxylic acid units is contained in the dicarboxylic acid unit in a total of 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95. It is at least mol%, and preferably at most 100 mol%. The dicarboxylic acid unit in the polyamide resin of the present invention preferably contains 70 mol% or more of adipic acid units in the dicarboxylic acid unit from the viewpoint of gas barrier properties and appropriate thermal properties such as glass transition temperature and melting point. . In addition, the type of dicarboxylic acid is appropriately determined according to the application, and from the viewpoint of imparting appropriate gas barrier properties and molding processability, it is preferable that the dicarboxylic acid unit contains 70 mol% or more of the dicarboxylic acid unit, and has low water absorption. When it is used for applications that require properties, weather resistance, and heat resistance, it is preferable that 1,12-dodecanedicarboxylic acid units are contained in the dicarboxylic acid unit in an amount of 70 mol% or more.

In the semi-aromatic polyamide (A), which is the semi-aromatic polyamide of the present invention, as a compound that can constitute a dicarboxylic acid unit other than the general formula (II), further imparting gas barrier properties and molding processability of the packaging material. From the viewpoint of facilitating, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and biphenyldicarboxylic acid may be included in the dicarboxylic acid unit in a range not exceeding 30 mol%. A range of mol% is preferred. Moreover, these can be used individually or in combination of 2 or more types.

(Diamine unit (III))
Next, the semiaromatic polyamide (B) will be described.
The diamine unit in the semi-aromatic polyamide (B) used in the present invention includes the aliphatic diamine unit represented by the formula (III) in the diamine unit from the viewpoint of imparting moderate flexibility and moderate crystallinity. 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less.

  In the general formula (III), R represents an aliphatic or alicyclic divalent group, and the divalent group has 2 to 18 carbon atoms, preferably 3 to 16, more preferably 4 to 14, more preferably Preferably it is 6-12. Examples of the compound that can constitute the aliphatic diamine unit represented by the general formula (III) include ethylenediamine, N-methylethylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and heptamethylene. Linear aliphatic diamines such as diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, etc., aliphatic diamines having side chains such as 2-methyl-1,5-pentane diamine, And 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane and the like. Is limited to these No. These can be used alone or in combination of two or more.

From the viewpoint of imparting flexibility, the diamine unit in the semi-aromatic polyamide (B) used in the present invention, as the diamine unit in the semi-aromatic polyamide (B), has a hexamethylenediamine unit in the diamine unit of 70 mol% or more. It is preferably contained, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less.

(Dicarboxylic acid unit (IV))
Next, the dicarboxylic acid unit in the semi-aromatic polyamide (B) is an aromatic dicarboxylic acid unit represented by the formula (IV) from the viewpoint of further imparting gas barrier properties and facilitating molding processability of the packaging material. Is contained in the dicarboxylic acid unit in an amount of 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less.

In the general formula (IV), Ar represents an arylene group.
The arylene group is preferably an arylene group having 6 to 30 carbon atoms, more preferably 6 to 15 carbon atoms, and examples thereof include a phenylene group and a naphthylene group.
Examples of the compound that can constitute the aromatic dicarboxylic acid unit represented by the general formula (IV) include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and anthracene dicarboxylic acid. Examples thereof include acids and ester-forming derivatives thereof, but are not limited thereto. These can be used alone or in combination of two or more.

The aromatic dicarboxylic acid unit represented by the general formula (IV) includes at least one selected from the group consisting of an isophthalic acid unit, a terephthalic acid unit and a 2,6-naphthalenedicarboxylic acid unit in the aromatic dicarboxylic acid unit. The total content is preferably 70 mol% or more, and the content is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less. It is. These can be used alone or in combination of two or more.
From the viewpoint of easy polymerization, isophthalic acid or a combination of isophthalic acid and terephthalic acid is preferably used.

The compound that can constitute a dicarboxylic acid unit other than the aromatic dicarboxylic acid unit represented by the general formula (IV) is 2 to 20 carbon atoms, preferably 4 to 16 carbon atoms, more preferably 4 to 12 carbon atoms. Aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, anhydrides of these acids, alkyl (C1-3) esters, and the like, but are not limited thereto.
Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, citraconic acid, 2 -Methyl succinic acid, itaconic acid, glutaconic acid and the like. Examples of alicyclic dicarboxylic acids include cyclohexane dicarboxylic acids and decalin dicarboxylic acids.

(Structural units other than diamine units and dicarboxylic acid units)
Examples of the compound that can constitute the structural unit other than the diamine unit and the dicarboxylic acid unit include trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid.

(Polyamide crystallinity)
The semi-aromatic polyamide resin used in the present invention preferably has a temperature-falling semi-crystallization time at 160 ° C. measured by a depolarization intensity method of 20 seconds or more. The reason for adopting that the temperature-decreasing semi-crystallization time of the polyamide is 20 seconds or more is that if it is less than 20 seconds, the crystallization speed is too high, and stretching unevenness and stretching breakage occur during biaxial stretching. It is. In general, polyamides with a long temperature-falling crystallization time, that is, a slow crystallization rate, have a low melting point and are close to the melting point of EVOH, so that the heat history can be kept low during melt mixing. It is also preferable from the viewpoint of suppressing the above.
Here, the temperature drop half crystallization time is 1% for crystallization by melting a pellet or film made of polyamide for 3 minutes in a hot air environment at 260 ° C. by a depolarizing intensity method and then crystallization in an oil bath at 160 ° C. / 2 represents the time to progress, and the shorter the half-crystallization time, the faster the crystallization speed of the material. The reason for crystallization at 160 ° C. is that the polyamide resin composition has the fastest crystallization speed and is easy to measure.

Examples of the semiaromatic polyamide used in the present invention include polyhexamethylene terephthalamide (polyamide 6T), polynonamethylene terephthalamide (polyamide 9T), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (polyamide 6IT), polymethylene Silylene adipamide (polyamide MXD6), isophthalic acid copolymer polymetaxylylene adipamide (polyamide MXD6I), polymetaxylylene sebamide (polyamide MXD10), polymetaxylylene decanamide (polyamide MXD12), polyparaxylylene Sebacamide (polyamide PXD10) and the like, more preferably polymetaxylylene adipamide, isophthalic acid copolymerized polymetaxylylene adipamide, and polyhexamethy Emissions terephthalamide / polyhexamethylene isophthalamide copolymers.

(Polyamide production method)
The polyamide used in the present invention can be produced by polycondensing a diamine component that can constitute the diamine unit and a dicarboxylic acid component that can constitute the dicarboxylic acid unit. A small amount of monoamine or monocarboxylic acid may be added as a molecular weight modifier during polycondensation.
Further, the ratio of the content of the diamine unit and the dicarboxylic acid unit is preferably substantially the same from the viewpoint of the polymerization reaction, and the content of the dicarboxylic acid unit is ± 2 mol of the content of the diamine unit. % Is more preferable. When the content of the dicarboxylic acid unit exceeds the range of ± 2 mol% of the content of the diamine unit, it becomes difficult to increase the polymerization degree of the polymer, so it takes a lot of time to increase the polymerization degree, and thermal degradation is caused. It tends to occur.

  As the polycondensation method of the polyamide used in the present invention, any method such as a generally known pressure method or atmospheric pressure dropping method can be used. As an example, it can be mentioned that the phosphorous atom-containing compound is added and it is produced by a melt polycondensation (melt polymerization) method. As the melt polycondensation method, for example, there is a method in which a nylon salt composed of a diamine component and a dicarboxylic acid component is heated in the presence of water under pressure and polymerized in a molten state while removing the added water and condensed water. is there. Moreover, it can manufacture also by the method of adding a diamine component directly to the dicarboxylic acid component of a melt-mixed state, and performing polycondensation. In this case, in order to keep the reaction system in a uniform liquid state without solidifying, the diamine component is continuously added to the dicarboxylic acid component so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide resins. The polycondensation proceeds while the reaction system is heated.

  Examples of the phosphorus atom-containing compound added to the polycondensation system of the polyamide used in the present invention include phosphinic acid compounds such as dimethylphosphinic acid and phenylmethylphosphinic acid; hypophosphorous acid, sodium hypophosphite, hypophosphorous acid Diphosphite compounds such as potassium, lithium hypophosphite, magnesium hypophosphite, calcium hypophosphite, ethyl hypophosphite; phosphonic acid, sodium phosphonate, potassium phosphonate, lithium phosphonate, potassium phosphonate, Phosphonation of magnesium phosphonate, calcium phosphonate, phenylphosphonic acid, ethylphosphonic acid, sodium phenylphosphonate, potassium phenylphosphonate, lithium phenylphosphonate, diethyl phenylphosphonate, sodium ethylphosphonate, potassium ethylphosphonate, etc. Phosphonous acid, sodium phosphonite, lithium phosphonite, potassium phosphonite, magnesium phosphonite, calcium phosphonite, phenylphosphonite, sodium phenylphosphonite, phenyl phenylphosphonite, phenyl phosphite Phosphorous acid compounds such as lithium phosphonate and ethyl phenylphosphonite; phosphorous acid, sodium hydrogen phosphite, sodium phosphite, lithium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, Examples include phosphorous compounds such as triethyl phosphate, triphenyl phosphite, pyrophosphorous acid, etc., and among these, hypo hypochlorite such as sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, etc. Metal phosphate is highly effective in promoting amidation and prevents coloration Is preferably used since the excellent result, especially sodium hypophosphite are preferred. In addition, the phosphorus atom containing compound which can be used by this invention is not limited to these compounds.

  The addition amount of the phosphorus atom-containing compound added to the polyamide polycondensation system used in the present invention is preferably 0.1 to 1000 ppm, more preferably 1 to 600 ppm in terms of phosphorus atom concentration in the polyamide resin. Yes, more preferably 5 to 400 ppm.

  Moreover, it is preferable to add an alkali metal compound in combination with the phosphorus atom-containing compound in the polycondensation system of the polyamide used in the present invention. In order to prevent the polyamide resin from being colored during the polycondensation, a sufficient amount of the phosphorus atom-containing compound needs to be present, but in some cases, the gelation of the polyamide resin may be caused. In order to adjust, it is preferable to coexist an alkali metal compound. As the alkali metal compound, alkali metal hydroxide, alkali metal acetate, alkali metal carbonate, alkali metal alkoxide, and the like are preferable. Specific 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. Sodium methoxide, sodium ethoxide, sodium propoxide, sodium butoxide, potassium methoxide, lithium methoxide, sodium carbonate and the like, but can be used without being limited to these compounds.

  The polyamide used in the present invention obtained by melt polycondensation can be used as it is, but may be subjected to a step for further increasing the degree of polymerization. Further examples of the step of increasing the degree of polymerization include reactive extrusion in an extruder and solid phase polymerization. As a heating device used in solid phase polymerization, a continuous heating drying device, a tumble dryer, a conical dryer, a rotary drum heating device called a rotary dryer, etc., and a rotary blade inside a nauta mixer are provided. A conical heating device can be preferably used, but a known method and device can be used without being limited thereto. Especially in the case of solid-phase polymerization of polyamide, the rotary drum type heating device in the above-mentioned device can seal the inside of the system, and it is easy to proceed with polycondensation in a state where oxygen that causes coloring is removed. Preferably used.

The relative viscosity is generally used for the degree of polymerization of the polyamide used in the present invention. In the case of forming a structure mainly composed of the polyamide of the present invention, the preferred relative viscosity is preferably 1.5 to 4.2, more preferably 1.7 from the viewpoint of the appearance of the molded product and molding processability. It is -4.0, More preferably, it is 2.0-3.8. However, when the polyamide of the present invention is used as an additive or modifier for other thermoplastic resins, it is not limited to this range.
The relative viscosity referred to here is that of 1 g of polyamide resin dissolved in 100 mL of 96% sulfuric acid, the drop time (t) measured at 25 ° C. with a Canon Fenske viscometer, and the 96% sulfuric acid itself measured in the same manner. It is the ratio of the drop time (t ₀ ) and is shown by the following formula.
Relative viscosity = t / t ₀

(Additive)
In the present invention, depending on the performance required for the biaxially stretched film of the present invention, a lubricant, a crystallization nucleating agent, a matting agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a plasticizer are included in the polyamide resin composition. Additives such as additives, flame retardants, antistatic agents, anti-coloring agents and antioxidants can be added. These additives can be added as necessary within a range not impairing the effects of the present invention. Furthermore, a thermoplastic resin such as an elastomer may be mixed in order to impart various physical properties such as impact resistance improvement.

A polyamide resin composition composed of EVOH and semi-aromatic polyamide is prepared by mixing a raw blend of EVOH and semi-aromatic polyamide directly into an extruder and melt-mixing them. Although obtained by producing a resin composition pellet blended with an aromatic polyamide, the present invention is not limited thereto.

The mixing ratio of EVOH and semi-aromatic polyamide in the polyamide resin composition constituting the biaxially stretched film of the present invention is such that EVOH is 99 to 55% by mass and semi-aromatic polyamide is 1 to 45% by mass. Is preferred. More preferably, the range of EVOH is 95 to 60% by mass and the semiaromatic polyamide is preferably 5 to 40% by mass, and particularly preferably EVOH is 90 to 70% by mass and the semiaromatic polyamide is 10%. It is the range of -30 mass%. When the EVOH ratio in the polyamide resin composition is less than 55% by mass, it is easy to perform biaxial stretching, but the oxygen barrier properties under low humidity conditions (23 ° C., 60% RH or less) deteriorate.

(Oxygen absorption performance)
In the present invention, a polyamide resin composition composed of a semi-aromatic polyamide having a temperature drop half-crystallization time at 160 ° C. of 20 seconds or more and EVOH, a transition metal of group VIII of the periodic table, manganese, copper and zinc One or more metal atoms selected from the above can be added as a compound or complex before the start of the polycondensation reaction, during the reaction, or at the time of extrusion molding, whereby oxygen absorption performance can be imparted. It is also possible to add oxygen-absorbing performance by adding a diene compound such as polybutadiene having an unsaturated double bond.

In the present invention, it is preferable to use a compound containing a metal atom (hereinafter referred to as a metal catalyst compound) to add and mix the metal atom into the polyamide resin composition. The metal catalyst compound is used in the form of a low-valent inorganic acid salt, organic acid salt or complex salt of the metal atom.
Examples of inorganic acid salts include halides such as chlorides and bromides, sulfates, nitrates, phosphates, silicates, and the like. On the other hand, examples of the organic acid salt include a carboxylate, a sulfonate, and a phosphonate. Also, transition metal complexes with β-diketone or β-keto acid ester can be used. Of these, carboxylates, halides, and acetylacetonate complexes containing the above metal atoms are preferred because of their good oxygen absorption function.
One or more of the metal catalyst compounds can be added, but those containing cobalt as a metal atom are particularly excellent in oxygen absorption function and are preferably used.

  The concentration of the metal atom added to the polyamide resin composition is not particularly limited, but is preferably in the range of 1 to 1000 ppm, more preferably 1 to 700 ppm with respect to 100 parts by mass of the polyamide resin. If the addition amount of the metal atom is 1 ppm or more, in addition to the gas barrier effect of the polyamide resin composition of the present invention, the oxygen absorbing function is sufficiently developed, and the effect of improving the oxygen barrier property of the packaging material is obtained. The method for adding the metal catalyst compound to the polyamide resin is not particularly limited, and can be added by any method.

(Manufacturing method of biaxially stretched film)
The manufacturing method of the stretched film of this invention is demonstrated. As a stretching method of the stretched film referred to in the present invention, there is a method of stretching a raw film for stretching prepared from a single layer or multilayer T die or a circular die by a roll stretching method, a tenter method, an inflation method (including a double bubble method), or the like. Yes, it is preferable to stretch by simultaneous biaxial stretching. In addition, the stretching is performed in at least one direction at an area stretching ratio of 4 to 80 times, and this stretching ratio may be appropriately selected depending on the required heat shrinkage rate. Moreover, you may perform well-known surface treatments, such as heat set process, corona treatment, and plasma treatment, as needed.
First, an unstretched film that is substantially amorphous and not oriented is produced from the raw material EVOH and semi-aromatic polyamide. In addition, although the thickness of this unstretched film of the polyamide resin composition which consists of EVOH film and semi-aromatic polyamide is suitably selected according to the use of a film and a draw ratio, it is the range of 60-1000 micrometers normally.

A filter such as a disk type or a pole type for adjusting the flow rate or pressure, removing foreign matter, etc., may be installed between the extrusion molding machine and the T die as necessary. Furthermore, you may install the thermogenizer for temperature maintenance, the heat exchanger for temperature control, etc.

For forming in the casting roll, an electrostatic pinning method, an air knife method, a vacuum chamber method or the like is applied. The polyamide resin composition melt-extruded from the T-die is usually brought into close contact with a casting roll maintained at a temperature of 60 ° C. or lower, preferably 40 ° C. or lower, and rapidly cooled to form an unstretched film.

The unstretched film is continuously subjected to a longitudinal stretching step, but prior to that, even if the moisture content of the unstretched film is adjusted by immersing it in a hot water bath at 40 ° C. or higher for improving stretchability. Good.

Next, biaxial stretching of an unstretched film will be described. In the present invention, a uniaxially stretched film is obtained by stretching the unstretched film in the machine direction in a temperature range of 50 to 70 ° C. and a stretch ratio of 2.5 to 4.0 times with a roll stretching machine. Then, the above-described uniaxially stretched film is stretched in the transverse direction by a tenter-type transverse stretching machine in a temperature range of 60 to 120 ° C. and a stretching ratio of 2.5 to 5.0 times. Furthermore, a method of heat-setting the above biaxially stretched film at 180 ° C. with 110 ° C. as the lower limit is preferably applied.

The roll type stretching machine is composed of a plurality of rolls and a plurality of nip rolls capable of temperature control and speed control, and by changing the linear speed of the low speed roll and the high speed roll in one stage or multiple stages, Various stretching ratios can be changed.

In the above longitudinal stretching, it is preferable to set the stretching temperature to a temperature between 50 ° C and 70 ° C. When the stretching temperature (film temperature) is 50 ° C. or higher, film breakage due to stretching stress can be suppressed. Further, when the stretching temperature is 70 ° C. or lower, the film does not stick to the stretching roll, and appropriate crystallization proceeds, so that the film can be easily formed.
In the longitudinal stretching, the stretching ratio is preferably stretched 2.5 to 4.0 times. If the draw ratio is 2.5 or more, a desired orientation can be imparted to the film. Further, when the draw ratio is 4.0 times or less, film forming is easy without breaking the film.
The film is preferably heated by a roll of a roll type longitudinal stretching machine.

The tenter type transverse stretching machine is described in, for example, Japanese Utility Model Publication No. 46-19426, Japanese Patent Publication No. 55-30977, Japanese Patent Publication No. 56-32089, Japanese Patent Publication No. 56-36853, etc. As is well known, the transverse stretch ratio can be variously changed by adjusting the distance between the tenters held at both ends in the film width direction.

In the transverse stretching, it is preferable that the stretching temperature is set to a temperature between 60 ° C and 120 ° C.
When the stretching temperature is 60 ° C. or higher, film breakage due to stretching stress can be suppressed. If the stretching temperature is 120 ° C. or lower, a desired orientation can be imparted to the film, and a film having excellent mechanical strength and good thickness accuracy can be obtained.
In the transverse stretching, the stretching ratio is preferably stretched 2.5 to 5.0 times. When the draw ratio is 2.5 times or more, a desired orientation can be imparted to the film. Moreover, if a draw ratio is 5.0 times or less, the fracture | rupture of the film at the time of shaping | molding can be suppressed.
The film may be heated by any method such as a hot air oven, a heater type oven, or a combination of both.

Said heat setting is performed in order to improve the dimensional stability of the biaxially stretched film. The heat setting temperature is preferably 110 to 180 ° C.
If the heat setting temperature is 110 ° C. or higher, the film can be sufficiently heat set. Moreover, if heat setting temperature is 180 degrees C or less, troubles, such as whitening of a film and a film being softened too much and a hole generate | occur | producing and a film fracture | rupture, can be suppressed. The heat setting may be performed in any state of a tensioned state or a relaxed state of the film, or a combination of both. The relaxation rate is preferably 10% or less. Moreover, the heating of a film can be performed similarly to the case of transverse stretching.

The transfer time (transfer time to the lateral stretching start position) of the uniaxially stretched film obtained in the longitudinal stretching process is preferably as short as possible, for example, within 5 seconds. Such short-time transfer effectively suppresses the progress of orientation and crystallization associated with longitudinal stretching, and effectively prevents film breakage that is a concern during transverse stretching. In addition, since the transverse stretching step is performed at a higher stretching temperature than the longitudinal stretching step, it is preferable to preheat the film to a necessary temperature during the above transfer.

(Thermoplastic resin used for multilayer film)
The biaxially stretched film of the present invention is used as it is, that is, as a single layer film, or as a multilayer film having at least one layer of the film. Such a multilayer body is obtained by coextrusion to form a multilayer biaxially stretched film by the above-described method, and other resin (film or sheet) on one side or both sides of the single layer or multilayer biaxially stretched film of the present invention. Obtained by laminating.

As the laminating method, for example, a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester compound is used, and the biaxially stretched film of the present invention and a base material made of another thermoplastic resin are laminated. The method etc. are mentioned.

Moreover, as a base material (film or sheet) made of the thermoplastic resin, polyolefin resin, polystyrene resin, polyester resin, polyamide resin, copolymerized polyamide resin, polyvinyl chloride resin, polyvinylidene chloride resin, acrylic resin , Vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, EVOH (EVOH 2 layers or more), and the like. Furthermore, paper, metal foil, woven fabric, non-woven fabric, metal cotton strip, wood surface, etc. can be used.

  Specific examples of polyolefins include olefin homopolymers such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene-propylene- Copolymer of ethylene and α-olefin such as polybutene-1 copolymer, ethylene-cyclic olefin copolymer; ethylene-α, β-unsaturated carboxylic acid copolymer, ethylene-α, β-unsaturated carboxylic acid Other ethylene such as acid ester copolymer, ionic cross-linked product of ethylene-α, β-unsaturated carboxylic acid copolymer, ethylene-vinyl acetate copolymer, part of ethylene-vinyl acetate copolymer or completely saponified product Copolymers; Grafts obtained by graft-modifying these polyolefins with acid anhydrides such as maleic anhydride Mention may be made of the gender polyolefin.

The polyester is a polyester composed of one or two or more selected from polycarboxylic acids containing dicarboxylic acids and ester-forming derivatives thereof, and one or more selected from polyhydric alcohols containing glycol, hydroxy A polyester comprising a carboxylic acid and an ester-forming derivative thereof, or a cyclic ester.

  Examples of the dicarboxylic acid constituting the polyester include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, tetradecanedicarboxylic acid, hexadecanedicarboxylic acid. Acid, 3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, dimer Saturated aliphatic dicarboxylic acids exemplified by acids and the like or ester-forming derivatives thereof, unsaturated aliphatic dicarboxylic acids exemplified by fumaric acid, maleic acid, itaconic acid and the like, or ester-forming derivatives thereof, orthophthalic acid, isophthalic acid acid Terephthalic acid, diphenic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4 ′ -Biphenyl dicarboxylic acid, 4,4'-biphenyl sulfone dicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acid, pamoic acid, anthracene dicarboxylic acid, etc. Aromatic dicarboxylic acids or ester-forming derivatives thereof, 5-sodium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid, 5-lithium sulfoisophthalic acid, 2-lithium sulfoterephthalic acid, 5-potassium sulfoisophthalic acid 2-potassium sulfoterephthalic acid Examples thereof include metal sulfonate group-containing aromatic dicarboxylic acids or their lower alkyl ester derivatives.

Among the above dicarboxylic acids, the use of terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid is preferable in terms of the physical properties of the resulting polyester, and other dicarboxylic acids may be copolymerized as necessary. .

  As polyvalent carboxylic acids other than these dicarboxylic acids, ethanetricarboxylic acid, propanetricarboxylic acid, butanetetracarboxylic acid, pyromellitic acid, trimellitic acid, trimesic acid, 3,4,3 ′, 4′-biphenyltetracarboxylic acid, And ester-forming derivatives thereof.

  Examples of the glycol constituting the polyester include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 2,3-butylene. Glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1, 2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, 1,10-decamethylene glycol, 1,12-dodecanediol, polyester Aliphatic glycol, hydroquinone, 4,4′-dihydroxybisphenol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4 exemplified by lenglycol, polytrimethylene glycol, polytetramethylene glycol and the like -Bis (β-hydroxyethoxyphenyl) sulfone, bis (p-hydroxyphenyl) ether, bis (p-hydroxyphenyl) sulfone, bis (p-hydroxyphenyl) methane, 1,2-bis (p-hydroxyphenyl) ethane , Bisphenol A, bisphenol C, 2,5-naphthalenediol, and glycols obtained by adding ethylene oxide to these glycols, and the like.

Among the above glycols, it is particularly preferable to use ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, and 1,4-cyclohexanedimethanol as the main component. Examples of polyhydric alcohols other than these glycols include trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, glycerol, and hexanetriol.
Examples of hydroxycarboxylic acids include lactic acid, citric acid, malic acid, tartaric acid, hydroxyacetic acid, 3-hydroxybutyric acid, p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, 4-hydroxycyclohexanecarboxylic acid, or these And ester-forming derivatives thereof.

  Examples of the cyclic ester include ε-caprolactone, β-propiolactone, β-methyl-β-propiolactone, δ-valerolactone, glycolide, and lactide.

  Examples of ester-forming derivatives of polyvalent carboxylic acids and hydroxycarboxylic acids include these alkyl esters, acid chlorides, acid anhydrides, and the like.

  The polyester used in the present invention is preferably a polyester in which the main acid component is terephthalic acid or an ester-forming derivative thereof or naphthalenedicarboxylic acid or an ester-forming derivative thereof, and the main glycol component is alkylene glycol.

  The polyester in which the main acid component is terephthalic acid or an ester-forming derivative thereof is preferably a polyester containing 70 mol% or more of terephthalic acid or an ester-forming derivative thereof in total with respect to the total acid component. Preferred is a polyester containing 80 mol% or more, and more preferred is a polyester containing 90 mol% or more. Similarly, the polyester in which the main acid component is naphthalenedicarboxylic acid or an ester-forming derivative thereof is preferably a polyester containing 70 mol% or more of naphthalenedicarboxylic acid or an ester-forming derivative thereof, more preferably 80%. Polyesters containing at least mol%, more preferably polyesters containing at least 90 mol%.

  Examples of the naphthalenedicarboxylic acid or ester-forming derivative thereof used in the present invention include 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid exemplified in the above dicarboxylic acids, 2, 6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, or ester-forming derivatives thereof are preferred.

  The polyester whose main glycol component is an alkylene glycol is preferably a polyester containing 70 mol% or more of the total amount of alkylene glycol with respect to all glycol components, more preferably a polyester containing 80 mol% or more, More preferably, it is a polyester containing 90 mol% or more. The alkylene glycol here may contain a substituent or an alicyclic structure in the molecular chain.

  The copolymer components other than the terephthalic acid / ethylene glycol are isophthalic acid, 2,6-naphthalenedicarboxylic acid, diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,2-propanediol, 1,3-propane. It is preferably at least one selected from the group consisting of diol and 2-methyl-1,3-propanediol in order to achieve both transparency and moldability. In particular, isophthalic acid, diethylene glycol, neopentyl glycol, 1 More preferred is at least one selected from the group consisting of 1,4-cyclohexanedimethanol.

  A preferred example of the polyester used in the present invention is a polyester whose main repeating unit is composed of ethylene terephthalate, more preferably a linear polyester containing 70 mol% or more of ethylene terephthalate units, and still more preferably an ethylene terephthalate unit. A linear polyester containing 80 mol% or more is particularly preferable, and a linear polyester containing 90 mol% or more of ethylene terephthalate units is particularly preferable.

  Another preferred example of the polyester used in the present invention is a polyester in which the main repeating unit is composed of ethylene-2,6-naphthalate, more preferably 70 mol% or more of ethylene-2,6-naphthalate unit. It is a linear polyester, more preferably a linear polyester containing 80 mol% or more of ethylene-2,6-naphthalate units, and particularly preferable is a linear polyester containing 90 mol% or more of ethylene-2,6-naphthalate units. Polyester.

  Other preferred examples of the polyester used in the present invention include linear polyesters containing 70 mol% or more of propylene terephthalate units, linear polyesters containing 70 mol% or more of propylene naphthalate units, and 1,4-cyclohexane. A linear polyester containing 70 mol% or more of dimethylene terephthalate units, a linear polyester containing 70 mol% or more of butylene naphthalate units, or a linear polyester containing 70 mol% or more of butylene terephthalate units.

  Other preferable examples of the polyester used in the present invention include polyglycolic acid obtained by polycondensation of glycolic acid or methyl glycolate or ring-opening polycondensation of glycolide. This polyglycolic acid may be copolymerized with other components such as lactide.

  In particular, the composition of the entire polyester is a combination of terephthalic acid / isophthalic acid // ethylene glycol, terephthalic acid // ethylene glycol / 1,4-cyclohexanedimethanol, and terephthalic acid // ethylene glycol / neopentyl glycol. It is preferable in order to satisfy both properties and moldability. Needless to say, a small amount (5 mol% or less) of diethylene glycol produced by dimerization of ethylene glycol may be included in the esterification (transesterification) reaction or polycondensation reaction.

The polyamide used by laminating with the biaxially stretched film made of the polyamide resin composition of the present invention is derived from polyamide or aliphatic diamine and aliphatic dicarboxylic acid whose main constituent units are units derived from lactam or aminocarboxylic acid. A unit derived from an aliphatic polyamide having a unit as a main structural unit, a partial aromatic polyamide having a unit derived from an aliphatic diamine and an aromatic dicarboxylic acid as a main structural unit, and a unit derived from an aromatic diamine and an aliphatic dicarboxylic acid Examples include partially aromatic polyamides having a main structural unit, and monomer units other than the main structural unit may be copolymerized as necessary.

  Examples of the lactam or aminocarboxylic acid include lactams such as ε-caprolactam and laurolactam, aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid, and aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid. .

  As the aliphatic diamine, an aliphatic diamine having 2 to 12 carbon atoms or a functional derivative thereof can be used. Furthermore, an alicyclic diamine may be used. The aliphatic diamine may be a linear aliphatic diamine or a branched chain aliphatic diamine. Specific examples of such linear aliphatic diamines include ethylenediamine, 1-methylethylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, Examples include aliphatic diamines such as nonamethylenediamine, decamethylenediamine, undecamethylenediamine, and dodecamethylenediamine. Specific examples of the alicyclic diamine include cyclohexanediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, and the like.

Moreover, as said aliphatic dicarboxylic acid, linear aliphatic dicarboxylic acid and alicyclic dicarboxylic acid are preferable, and also linear aliphatic dicarboxylic acid which has a C4-C12 alkylene group is especially preferable. Examples of such linear aliphatic dicarboxylic acids include adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanoic acid, undecadioic acid, dodecanedioic acid, dimer Examples thereof include acids and functional derivatives thereof. Examples of the alicyclic dicarboxylic acid include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid.

  Examples of the aromatic diamine include metaxylylenediamine, paraxylylenediamine, para-bis (2-aminoethyl) benzene, and the like.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and functional derivatives thereof. It is done.

Specific polyamides include polyamide 4, polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 4, 6, polyamide 6, 6, polyamide 6, 10, polyamide 6T, polyamide 9T, polyamide 6IT, polymetaxylylene azide. Pamide (Polyamide MXD6), Isophthalic acid copolymer polymetaxylylene adipamide (Polyamide MXD6I), Polymetaxylylene sebamide (Polyamide MXD10), Polymetaxylylene decanamide (Polyamide MXD12), Poly 1,3-bis Examples include aminocyclohexane adipamide (polyamide BAC6) and polyparaxylylene sebacamide (polyamide PXD10). More preferable polyamides include polyamide 6, polyamide MXD6, and polyamide MXD6I.

  Further, as a copolymerization component of the polyamide, a polyether having at least one terminal amino group or a terminal carboxyl group and a number average molecular weight of 2000 to 20000, or an organic carboxylate of the polyether having the terminal amino group, or An amino salt of a polyether having a terminal carboxyl group can also be used. Specific examples include bis (aminopropyl) poly (ethylene oxide) (polyethylene glycol having a number average molecular weight of 2000 to 20000).

  The partially aromatic polyamide may contain a structural unit derived from a polybasic carboxylic acid having 3 or more bases such as trimellitic acid and pyromellitic acid within a substantially linear range.

  The polyamide is basically a conventionally known melt polycondensation method in the presence of water, a melt polycondensation method in the absence of water, or a polyamide obtained by these melt polycondensation methods. It can be manufactured by the method to do. The melt polycondensation reaction may be performed in one stage or may be performed in multiple stages. These may be comprised from a batch-type reaction apparatus, and may be comprised from the continuous-type reaction apparatus. The melt polycondensation step and the solid phase polymerization step may be operated continuously or may be operated separately.

  Rubbers that can be used in combination with these thermoplastic resins include natural rubber, polybutadiene rubber, polyisoprene rubber, poly (acrylonitrile-butadiene) rubber, poly (styrene-butadiene) rubber, poly (ethylene-propylene-diene) rubber, acrylic. Examples thereof include rubber and polyamide-based elastomer.

As a layer structure of the laminate, a single-layer or multilayer biaxially stretched film layer of the present invention is A (A1, A2,...), And a base material made of another thermoplastic resin is B (B1, B2,. In addition to the A / B two-layer structure, B / A / B, A / B / A, A1 / A2 / B, A / B1 / B2, B2 / B1 / A / Arbitrary combinations such as B1 / B2 are possible.

The biaxially stretched film and laminated film of the present invention can be further coated with a thin film.
The above coating materials include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-acrylic acid ester copolymer. Polymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene and other olefins alone or copolymers, and these olefins alone or copolymers unsaturated carboxylic acids Graft-modified polyolefin resin, polystyrene resin, polyester, polyamide, copolymer polyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyester elastomer, polyurethane resin Rustomer, chlorinated polyethylene, chlorinated polypropylene, EVOH and the like can be mentioned, and further, inorganic materials such as metals and silicon can be used. As a coating method, a vapor deposition method or the like is appropriately selected and applied in addition to a method of applying and drying a solution of a coating substance. The coating may be performed either before or after the lamination.

  The biaxially stretched film of the present invention can be used for any application requiring oxygen barrier properties such as various packaging materials and industrial materials. 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. In addition, in the packaging material or packaging container using the polyamide resin composition of the present invention, the thickness of the layer using the biaxially stretched film is not particularly limited, but has a thickness of 1 μm or more. It is preferable to form a layer.

  The packaging container comprising the biaxially stretched film of the present invention includes, for example, carbonated drinks, juice, water, milk, sake, whiskey, shochu, coffee, tea, jelly drinks, liquid drinks such as health drinks, seasoning liquids, sauces, Liquid systems such as soy sauce, dressing, soup stock, seasonings such as mayonnaise, miso, and spices, paste foods such as jam, cream, and chocolate paste, and liquid processed foods such as liquid soups, boiled foods, pickles, and stews Raw noodles such as food and soba, udon, ramen and boiled noodles, polished rice, moisture-conditioned rice, unwashed rice and other cooked rice products, cooked cooked rice, gomoku rice, red rice, rice bran and other processed rice products, Powdered soup, powdered seasonings such as dashi-no-moto, high moisture foods typified by jelly, pudding, etc., typified by sweets made from dried vegetables, coffee beans, coffee powder, tea, grains, etc. Moisture foods, other solid and solution chemicals such as agricultural chemicals and insecticides, liquid and paste pharmaceuticals, lotions, cosmetic creams, cosmetic emulsions, hair conditioners, hair dyes, shampoos, soaps, detergents, semiconductors, etc. Various items such as electronic devices can be stored. In particular, it is suitable for packaging containers filled with beverages, foods and the like that require hot water filling, boil sterilization, retort sterilization, and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In addition, the measurement for evaluation in this invention was based on the following method.
(1) Relative viscosity of polyamide resin 0.2 g of polyamide resin was precisely weighed and dissolved in 100 ml of 96% sulfuric acid at 20-30 ° C. with stirring. After completely dissolving, 5 ml of the solution was quickly taken into a Cannon-Fenceke viscometer and allowed to stand for 10 minutes in a constant temperature bath at 25 ° C., and then the drop time (t) was measured. Further, the dropping time (t0) of 96% sulfuric acid itself was measured in the same manner. And relative viscosity was computed from these t and t0 by following formula (2).
Relative viscosity = t / t0 (2)

(2) Temperature-lowering semi-crystallization time of polyamide resin composition Using a semi-crystallization time measuring apparatus (trade name: MK701, manufactured by Kotaki Seisakusho Co., Ltd.), a film of polyamide resin composition having a thickness of 100 μm was obtained by depolarizing strength method. The half-crystallization time was expressed as the time required for the crystallization to proceed 1/2 when crystallization was carried out in a hot air environment at 260 ° C. for 3 minutes and then crystallized in an oil bath at 160 ° C.

(3) Oxygen permeability coefficient of biaxially stretched film Oxygen at 23 ° C. and 90% RH of a 100 μm film using an oxygen permeability measuring device (Mocon, model: OX-TRAN 2 / 21SH) according to ASTM D3985 The transmittance and the oxygen permeability at 23 ° C. and 60% RH were measured, and converted to the oxygen permeability coefficient (cc · mm / (m ² · day · atm)) under each measurement condition. The lower the value, the less oxygen permeation is preferable.

Example 1

(Unstretched film production)
EVOH (Kuraray Co., Ltd. EVAL F101B: ethylene content: 32%, saponification degree of vinyl acetate component: 99.8%) and N-MXD6 (Mitsubishi Gas Chemical Co., Ltd. MX nylon solid phase polymerized product S6007, relative viscosity : 2.65) pellets obtained by dry blending at a ratio of 95 to 5% by mass. Using a 25 mmφ single screw extruder, a film was formed at an extrusion temperature of 250 ° C., a screw speed of 60 rpm, and a take-up speed of 1.2 m / min. A single-layer unstretched film having a thickness of 200 mm and a thickness of 150 μm was produced.

(Biaxially stretched film production)
This unstretched film was stretched 3 times in the MD direction and 3 times in the TD direction at a stretching temperature of 105 ° C. using a biaxial stretching device (tenter method) manufactured by Toyo Seiki Seisakusho, and heated at 160 ° C. for 30 seconds. The biaxially stretched film having a thickness of about 17 μm was obtained.

Example 2
A biaxially stretched film was obtained in the same manner as in Example 1 except that the ratio of EVOH and N-MXD6 was changed to 90 to 10% by mass.

Example 3
A biaxially stretched film was obtained in the same manner as in Example 1 except that the ratio of EVOH and N-MXD6 was changed to 80 to 20% by mass.

Example 4
A biaxially stretched film was obtained in the same manner as in Example 1 except that the ratio of EVOH and N-MXD6 was changed to 70 to 30% by mass.

Example 5
A biaxially stretched film was obtained in the same manner as in Example 4 except that N-MXD6 was changed to # 6003 (Mitsubishi Gas Chemical Co., Ltd., relative viscosity: 2.2) which is a melt polymerization product.

Example 6
N-MXD6 was changed to N-MXD6 (relative viscosity: 2.65) copolymerized with 6 mol% of isophthalic acid, and the molding temperature of the unstretched film was changed to 245 ° C. in the same manner as in Example 4. An axially stretched film was obtained.

Example 7
A biaxially stretched film was obtained in the same manner as in Example 4 except that cobalt stearate was added so that the cobalt content was 5 ppm with respect to the polyamide resin composition.

Example 8
A biaxially stretched film was obtained in the same manner as in Example 4 except that cobalt stearate was added so that the cobalt content was 200 ppm with respect to the polyamide resin composition.

Example 9
A biaxially stretched film was obtained in the same manner as in Example 8, except that the ratio of EVOH and N-MXD6 was changed to 60 to 40% by mass.

Example 10
A biaxially stretched film was obtained in the same manner as in Example 4 except that cobalt stearate was added so that the cobalt content was 800 ppm with respect to the polyamide resin composition.

Example 11
A biaxially stretched film was obtained in the same manner as in Example 4 except that the semiaromatic polyamide was changed to N-6IT (Novamid X21 manufactured by Mitsubishi Chemical Corporation). In addition, since the semi-crystallization time of polyamide was as long as 1000 seconds or more, it was not measured after that.

Example 12
A biaxially stretched film was obtained in the same manner as in Example 4 except that the stretching ratio was changed to 4 times in the MD direction and 4 times in the TD direction.

Comparative Example 1
Except for changing only to EVOH (Eval F101B manufactured by Kuraray Co., Ltd.), an attempt was made to obtain a biaxially stretched film by the same method as in Example 1, but film breakage occurred frequently and a biaxially stretched film could not be obtained. It was.

Comparative Example 2
Except that the stretching temperature was changed to 70 ° C., an attempt was made to obtain a biaxially stretched film by the same method as in Comparative Example 1, but film breakage occurred frequently and a biaxially stretched film could not be obtained.

Comparative Example 3
A biaxially stretched film was obtained in the same manner as in Example 1 except that only N-MXD6 (S6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used.

Comparative Example 4
Although it tried to obtain a biaxially stretched film by the same method as Example 4 except having changed to N-6 (1024B by Ube Industries, Ltd.) whose half crystallization time is 15 seconds, film breakage was carried out. Many times, biaxially stretched film was not obtained.

Comparative Example 5
A biaxially stretched film was obtained in the same manner as in Comparative Example 1 except that the ratio of EVOH and N-MXD6 was changed to 45: 55% by mass.

・ＥＶＯＨ(グレード：Ｆ１０１Ｂ)：ポリエチレンビニルアルコール共重合体（クラレ株式会社製）
・Ｎ―ＭＸＤ６（グレード：Ｓ６００７）：ポリメタキシリレンアジパミド固相重合品（三菱ガス化学株式会社製、相対粘度：２．６５）
・Ｎ―ＭＸＤ６（グレード：６００３）：ポリメタキシリレンアジパミド溶融重合品（三菱ガス化学株式会社製、相対粘度：２．２）
・イソフタル酸６モル％共重合Ｎ−ＭＸＤ６（相対粘度：２．６５）
・Ｎ−６ＩＴ：ポリヘキサメチレンテレフタルアミド／ポリヘキサメチレンイソフタルアミドコポリマー（三菱化学株式会社製 ノバミッドＸ２１）
・Ｎ−６（グレード：１０２４Ｂ）：ナイロン６（宇部興産株式会社製）

EVOH (grade: F101B): Polyethylene vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd.)
N-MXD6 (grade: S6007): polymetaxylylene adipamide solid phase polymerization product (Mitsubishi Gas Chemical Co., Ltd., relative viscosity: 2.65)
N-MXD6 (grade: 6003): polymetaxylylene adipamide melt polymerized product (Mitsubishi Gas Chemical Co., Ltd., relative viscosity: 2.2)
-Isophthalic acid 6 mol% copolymerization N-MXD6 (relative viscosity: 2.65)
N-6IT: polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (Novamid X21 manufactured by Mitsubishi Chemical Corporation)
N-6 (grade: 1024B): nylon 6 (manufactured by Ube Industries)

A biaxially stretched film composed of EVOH and a semi-aromatic polyamide having a semicrystallization time of 20 seconds or more can produce a biaxially stretched film with almost no film breakage, and has a high 23 ° C. and 90% RH. Even under humidity, the oxygen barrier property was better (Examples 1 to 12) than the single-layer biaxially stretched film of N-MXD6 (Comparative Example 3). In particular, by adding a cobalt compound and imparting an oxygen absorption capacity, an even better oxygen transmission coefficient was shown (Examples 7 to 10).
On the other hand, when biaxial stretching was performed only with EVOH, a biaxially stretched film could not be obtained due to film breakage (Comparative Examples 1 and 2). Moreover, even when polyamide 6 which is an aliphatic polyamide and has a semicrystallization time of less than 20 seconds was blended, film breakage occurred and a biaxially stretched film could not be obtained (Comparative Example 4). Furthermore, a biaxially stretched film obtained by blending EVOH and N-MXD6 at a ratio of 45 to 65% by mass is easy to stretch but has a low oxygen barrier property under low humidity conditions (23 ° C., 60% RH or less). (Comparative Example 5).

  Since the biaxially stretched film of the present invention has good moldability and is excellent not only in low humidity conditions but also in oxygen barrier properties under high humidity, it is suitably used as a packaging container for foods that require hot water sterilization treatment. be able to.

Claims (3)

Biaxial stretching having a layer made of a polyamide resin composition comprising 99 to 55% by mass of an ethylene vinyl alcohol copolymer and 1 to 45% by mass of a semi-aromatic polyamide having a temperature decrease and crystallization time at 160 ° C. of 20 seconds or more. It is a film , The said semi-aromatic polyamide has 80 to 97 mol% of diamine units containing 70 mol% or more of xylylenediamine units, linear aliphatic dicarboxylic acid units of 4 to 20 carbon atoms, and 3 isophthalic acid units. A biaxially stretched film, which is a polyamide containing dicarboxylic acid units containing ˜20 mol%. 2. The biaxially stretched film according to claim 1, wherein the polyamide resin composition contains 1 ppm or more of one or more metal atoms selected from Group VIII transition metals of the periodic table, manganese, copper, and zinc. The biaxially stretched film according to claim 1 or 2 , wherein the biaxially stretched film is used for a packaging container subjected to a hot water sterilization treatment.