JP2011083894A - Surface-treated laminated polyamide based film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a surface-treated laminated polyamide based film which has good lamination strength in high humidity, gas-barrier properties, and good characteristics in terms of low hot water shrinkability and thickness accuracy and can appropriately be used as a base material film of packaging bags for, for example, food, chemicals, industrial products, etc., and a method for producing the film. <P>SOLUTION: In the laminated polyamide based film having a laminated structure including at least two layers of a layer (a) containing an aliphatic polyamide based resin (A) as a main component and a layer (b) containing an aromatic polyamide based resin (B) as a main component, on at least one surface of the surface-treated laminated polyamide based film, the lamination strength in moistened condition of a surface-treated surface subjected to surface treatment by discharge treatment in an atmosphere in which the concentration of an inert gas is at least 99%, and the concentration of an active gas is 1% or below is at least 3.9 N/15 mm, and oxygen permeability under the condition of 25°C×50% RH is 80 fmol/(m2/sec/Pa) or below. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has excellent laminating strength and gas barrier properties when wet, and also has excellent properties such as low hot water shrinkage and thickness accuracy. For example, a base film for packaging bags of food, medicine, industrial products, etc. The present invention relates to a surface-treated polyamide-based laminate film, a surface-treated polyamide-based laminate film, and a method for producing the same.

Films mainly composed of polyamide resins such as nylon 6 and laminated films composed of polyamide resins as layers are excellent in tensile strength and impact strength, so that these polyamide-based films can be used for packaging foods, medicines, etc. It is secondarily processed into packaging bags and manufactured and sold in various forms.

In recent years, adaptation to retort sterilization has become important from the viewpoint of consumer convenience, extension of the expiration date, and improvement of storage stability. Usually, when using a polyamide-based film for such an application (after printing in many cases), a laminate film is prepared by laminating with a sealant film or other films, and the sealant layers of the laminate film are bonded together. After heat-sealing to form a bag and filling the contents, the opening is sealed by heat-sealing and used as a container. Moreover, the method of extending the shelf life of a content or maintaining a flavor is performed by performing the retort sterilization process at high temperature after filling with the content. However, since the internal pressure increases during the retort process, troubles such as broken bags and delamination often occur when a retort process is performed on a packaging bag using a film having poor laminate strength.

Therefore, a packaging material that does not cause defects such as broken bags or delamination when retort sterilizing at high temperature after filling the contents with a bag made of a composite film made of a functional resin film such as nylon and a sealant. It has been demanded. Properties required for the functional resin film used for such a packaging material include basic properties such as strength and gas barrier properties, and high laminate strength to prevent delamination.

Here, for example, in Patent Document 1, there is a method of controlling the orientation of the resin on the film surface layer as means for imparting high laminate strength to the functional resin film itself such as nylon of the polyamide film. However, in this case, the purpose is to prevent delamination due to cohesive peeling of the film surface, and it does not improve the adhesive force between the adhesive and the film, so the substantial laminate strength is not improved.

In addition, as another method, for example, Patent Document 2 proposes a method for preventing troubles such as printing omission due to processing unevenness by uniformly processing a polyamide film by performing surface treatment twice or more. . However, the uniform treatment can prevent printing omission due to treatment unevenness and decrease in the laminate strength, but it does not improve the laminate strength itself, so it has not led to a fundamental solution.

Patent Document 3 describes a method of bonding films without using an adhesive layer by treating the film surface with nitrogen atoms. However, in this method, the laminate strength when wet is as low as 2.0 N / 15 mm or more, and it cannot be used for applications requiring high wet laminate strength such as retort treatment.

JP-A-9-239930 JP2008-297416 JP2007-307771

Accordingly, an object of the present invention is to provide a surface-treated polyamide-based laminated film having excellent mechanical strength such as tensile strength and impact strength, as well as high wet laminate strength and gas barrier properties, and a method for producing the same. .

In view of the current situation, the present inventors have made extensive studies and have found a polyamide-based film that can solve the conventional problems.
That is, this invention provides the following surface treatment polyamide-type laminated | multilayer film and its manufacturing method.

1. In a polyamide-based resin laminated film having a laminated structure including at least two layers of (a) a layer mainly composed of an aliphatic polyamide resin (A) and (b) a layer mainly composed of an aromatic polyamide resin (B) The laminate strength when the surface-treated surface is wet is 3.9 N, on which at least one surface of the film is subjected to surface treatment by discharge treatment in an atmosphere having an inert gas concentration of 99% or more and an active gas concentration of 1% or less. / 15 mm or more and a surface-treated polyamide-based laminated film having an oxygen permeability of 80 fmol / (m 2 · sec · Pa) or less under the condition of 25 ° C. × 50% RH.
2. Between the (a) layer containing the aliphatic polyamide resin as a main component and the (b) layer containing the aromatic polyamide resin as a main component, 65-100% by mass of the aliphatic polyamide resin (A) and aromatic 2. The surface-treated polyamide-based laminated film according to 1 above, having a (c) layer containing 0 to 35% by mass of the polyamide resin (B).
3. 3. The surface-treated polyamide-based laminated film according to 1 or 2 above, wherein the aliphatic polyamide polymer (A) is nylon 6 and the aromatic polyamide polymer (B) is polymetaxylylene adipamide.
4). The surface-treated polyamide-based laminated film according to any one of 1 to 3 above, wherein a thickness of the (b) layer containing the aromatic polyamide resin as a main component is 2 to 7 μm.
5). 5. The surface-treated polyamide film according to any one of 1 to 4 above, wherein the inert gas is nitrogen.
6. The hot water shrinkage rate in the film flow direction (MD) at 6.95 ° C. × 5 minutes is 3.0% or less, and the thickness variation rate in the width direction (TD) of the film is 10% or less of the average thickness. The surface-treated polyamide-based laminated film according to any one of 1 to 5.
7). 7. The surface-treated polyamide-based laminated film according to any one of 1 to 6 above, wherein the atmosphere during the surface treatment is an inert gas concentration of 99% or more, an active gas concentration of 1% or less, and a reactive gas concentration of 1% or less.
8). The surface-treated polyamide system comprising a multilayer structure in which the surface-treated surface in the surface-treated polyamide-based laminated film according to any one of 1 to 7 is disposed so as to constitute at least one surface of the resin laminate. Laminated film.
9. 9. A surface-treated polyamide-based laminate film obtained by laminating a sealant film on the surface-treated surface of the surface-treated polyamide-based laminated film according to any one of 1 to 8 above.
10. A bag comprising the surface-treated polyamide-based laminate film as described in 9 above.
11. After the step of stretching an unstretched film extruded from a flat die by a tenter-type sequential biaxial stretching method at a stretching ratio of 2.4 times or more for both MD and TD, the aliphatic polyamide polymer (A ) Extrapolated melting start temperature (measured in accordance with JIS K 7121) through a process of heat setting at a temperature not higher than 10 ° C., and at least one surface of the film has an inert gas concentration of 99% or more and an active gas A method for producing a surface-treated polyamide-based laminated film comprising a step of performing a surface treatment by an electric discharge treatment in an atmosphere having a concentration of 1% or less.

According to the present invention, it is excellent in mechanical strength such as tensile strength and impact strength, and also has a high wet laminate strength, a surface-treated polyamide-based laminated film having gas barrier properties, and also has low hot water shrinkage and thickness accuracy. It is possible to provide a surface-treated polyamide-based laminated film having excellent characteristics and a method for producing the same.

Hereinafter, the present invention will be described in detail, but the scope of the present invention is not limited to the embodiments described below.
First, the surface-treated polyamide-based laminated film of the present invention is a laminated film having at least one (a) layer and (b) layer.

  Here, as the layer structure, a two-layer structure (a) / (b), a three-layer structure (a) / (b) / (a), (b) / (a) / (b), (A) / (c) / (b) / (c) / (a), (b) / (c) / (a) / (c) / (b ) And the like, but from the viewpoint of the productivity of the laminated film and the secondary processability such as laminating to the bag, etc., the three-layer structure of (a) / (b) / (a), ( A five-layer structure of a) / (c) / (b) / (c) / (a) is preferably used.

  The total thickness of the surface-treated polyamide-based laminated film of the present invention should be 10 to 50 μm from the viewpoint of being suitable for soft packaging applications, such as the balance between oxygen gas barrier properties and pinhole resistance. It is preferable in obtaining.

The total content of the layer (a) and the layer (b) (including the layer (c)) is preferably 50% or more of the entire film.
The layer (a) is preferably 40% or more and 6 μm or more of the entire film in order to maintain mechanical strength. (A) When two or more layers are comprised in a laminated | multilayer film, it is preferable that the total thickness exists in the said range. In that case, it is preferable that at least one layer (a) of 3 μm or more is included.
The (b) layer is preferably 40% or less of the entire film and 2 to 7 μm. More preferably, it is 3-6 micrometers. Here, when 2 or more layers are comprised in a laminated | multilayer film, it is preferable that the total thickness exists in the said range.
Here, if the thickness of the (b) layer is 2 μm or more, it is preferable because the oxygen transmission rate under the condition of 25 ° C. × 50% RH is 80 fmol / (m 2 · sec · Pa) or less. Moreover, it is preferable if the thickness of the layer (b) is 40% or less of the whole film and 7 μm or less because the mechanical strength is good.

  The layer (a) is a layer mainly composed of the aliphatic polyamide resin (A), the aliphatic polyamide resin (A) being 65 to 100% by mass, and the aromatic polyamide resin (B) being 0 to 35% by mass. It is preferable to use a mixture of the aliphatic polyamide resin (A) and the aromatic polyamide resin (B). If the aromatic polyamide resin (B) is within this range, it is possible to suppress a significant decrease in the impact strength of the resulting film.

  Here, the mixture of the aliphatic polyamide resin (A) and the aromatic polyamide resin (B) is generated when the raw material resins (pellets and the like) are mixed with each other or when the polyamide-based film of the present invention is produced in these. A non-standard film or a cut end material (ear trim) may be mixed.

  The layer (b) is a layer mainly composed of the aromatic polyamide resin (B), and the content of the aromatic polyamide resin (B) is preferably 90 to 100% by mass. If the aromatic polyamide resin (B) is 90% by mass or more, sufficient gas barrier properties can be imparted to the film. Here, the layer (b) may contain a small amount (about 10% by mass or less) of an aliphatic polyamide resin (A) or a bending-resistant pinhole improving material.

  The aliphatic polyamide resin (A) used in the surface-treated polyamide-based laminated film of the present invention is not particularly limited, but is a ring-opening polymer of a cyclic lactam, a polycondensate of an aminocarboxylic acid, a dicarboxylic acid and a diamine. Examples include polycondensates. Specifically, a homopolymer of ε-caprolactam called nylon 6 or polyhexamethylene adipamide called nylon 66 can be obtained at low cost, and the stretching operation can be performed smoothly. To preferred.

  Further, the aromatic polyamide resin (B) is not particularly limited, but 70 mol% of a polyamide constituent unit composed of xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain. Resins containing the above can be used. Specifically, homopolymers such as polymetaxylylene adipamide, polymetaxylylene pimeramide, polymetaxylylene azelamide, polyparaxylylene azelamide, polyparaxylylene decanamide, metaxylylene / paraxylylene azamide Examples of the copolymer include a pamide copolymer, a metaxylylene / paraxylylene pimeramide copolymer, a metaxylylene / paraxylylene azelamide copolymer, and a metaxylylene / paraxylylene sepacamide copolymer. Polymetaxylylene adipamide (hereinafter referred to as “MXD6”) is preferable because it has excellent basic properties such as strength and gas barrier properties, and is relatively easy to obtain industrially.

  Examples of the polyamide constituents other than (A) and (B) include nylon salts of diamines and dicarboxylic acids, lactams such as ε-caprolactam, ω-aminocarboxylic acids such as ε-aminocarboxylic acid, and the like. These can be contained in the surface-treated polyamide-based laminated film of the present invention.

  The diamines that are the components of the nylon salt include aliphatic diamines such as hexamethylene diamine and 2,2,4-trimethylhexamethylene diamine, heterocycles or heteroatoms such as piperazine bispropylamine and neopentylglycol bispropylamine. Dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and 1,4-cyclohexanedigalbonic acid. And cycloaliphatic dicarboxylic acids.

  In the present invention, the adhesive layer (c) is preferably provided from the viewpoint of improving interlayer adhesion between the (a) layer and the (b) layer. Although there is no restriction | limiting in particular as a component which comprises an adhesive layer, It is using the mixture of the said aliphatic polyamide resin (A) and the said aromatic polyamide resin (B), polyolefin-type, polyester-type adhesive resins, etc. it can.

The content ratio of the aliphatic polyamide resin (A) and the aromatic polyamide resin (B) in the layer (c) is 65 to 90% by mass of the aliphatic polyamide resin (A) and 10 of the aromatic polyamide resin (B). It is preferable to set it to -35 mass%. When the aromatic polyamide resin (B) is within this range, the interlayer adhesion of the resulting film can be improved, and a significant reduction in impact strength can be suppressed.

  A bending-resistant pinhole property improving material can be added to the surface-treated polyamide-based laminated film of the present invention, whereby the bending-resistant pinhole property can be improved. Examples of the bending-resistant pinhole improving material include polyolefins, polyamide elastomers, and polyester elastomers.

  Examples of polyolefins include those containing 50 mass% or more of polyethylene units and / or polypropylene units in the main chain, and may be graft-modified with maleic anhydride or the like. As structural units other than the polyethylene unit and the polypropylene unit, vinyl acetate or a partially saponified product thereof, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, or a partial metal neutralized product thereof (ionomers), butene 1-alkenes such as alkadienes, styrene and the like. Polyolefins may contain a plurality of these structural units.

  Examples of polyamide elastomers include polyamide block copolymers such as polyether amide and polyether ester amide. Examples of the amide component include nylon 6, nylon 66, nylon 12, and the like. Examples thereof include oxytetramethylene glycol, polyoxyethylene glycol, polyoxy-1,2-propylene glycol and the like, and a copolymer having polytetramethylene glycol and polylauryl lactam (nylon 12) as main components is preferable. Further, a combination of a small amount of dicarboxylic acids such as dodecanedicarboxylic acid, adipic acid and terephthalic acid as an optional component may be used.

Examples of polyester elastomers include polyether ester elastomers combining polybutylene terephthalate and polytetramethylene glycol, and polyester ester elastomers combining polybutylene terephthalate and polycaprolactone.
These bending-resistant pinhole improving materials may be used alone or in combination of two or more.

  In the present invention, the addition amount of the bending-resistant pinhole property improving material is the above-mentioned (a) to (c) from the viewpoint of the balance between the improvement effect of bending-resistant pinhole property and the decrease in transparency when it is used as a film. In each layer, the amount is about 0.1 to 10% by mass. Here, as the aliphatic polyamide polymer (A) and the aromatic polyamide polymer (B) containing the bending pinhole resistance improving material, those obtained by dry blending these at a predetermined ratio, or the dry blend product is extruded in advance. It may be any of those pelletized after being melt-mixed by a machine.

The above-mentioned aliphatic polyamide resin (A) has an impact modifier, a lubricant, an antistatic agent, an antioxidant, an antiblocking agent, a stable agent, as necessary, within the range not exceeding the gist of the present invention. Various additives such as an agent, a dye, a pigment, and inorganic fine particles can be added. Specific examples include impact modifiers (such as elastomers), anti-blocking agents (such as inorganic fillers), water repellents (such as ethylene bisstearic acid esters), and lubricants (such as ethylene bisstearic acid amides).

When using the surface-treated polyamide laminated film of the present invention as a packaging bag, from the viewpoint of maintaining the quality of the contents and preventing spoilage, further laminating a gas barrier resin layer, metals such as aluminum, silicon dioxide, The gas barrier property and moisture proof property can be further improved by vapor-depositing a metal oxide such as alumina and applying a gas barrier coating agent.

The surface-treated polyamide-based laminated film of the present invention includes a non-standard film and a cut end that are generated when the surface-treated polyamide-based laminated film of the present invention is produced, as necessary, within the range not exceeding the gist of the present invention. A material (ear trim) can be added to each of the layers (a), (b) and (c), or a plurality of layers.

Next, the surface-treated polyamide laminated film of the present invention has the following features (1) to (4). These can be controlled mainly by the film production conditions (stretch ratio, heat setting temperature, etc.) and surface treatment.

(1) The laminate strength when wet must be 3.9 N / 15 mm or more. Here, if the laminate strength when wet is 3.9 N / 15 mm or more, troubles such as delamination and broken bags are unlikely to occur even in a state where stress is applied by lamination, retort processing after bag making, or the like.
Furthermore, the laminate strength when wet is preferably 4.9 N / 15 mm or more. If the laminate strength when wet is 4.9 N / 15 mm or more, troubles such as delamination and broken bags are unlikely to occur even when used in packaging bags that are constantly subjected to strong stress such as airbag packaging bags.
In the present invention, the “lamination strength when wet” refers to the peel strength between the laminated surface-treated polyamide laminated film and the sealant, and is specifically a value obtained by the measurement method described later.

(2) The oxygen permeability under the condition of 25 ° C. × 50% RH needs to be 80 fmol / (m 2 · sec · Pa) or less. Here, if the oxygen permeability is 80 fmol / (m 2 · sec · Pa) or less, sufficient gas barrier properties can be obtained, and applications that require high gas barrier properties such as preservation of contents and improvement of shell life are required. Can be used for

(3) It is preferable that the hot water shrinkage in the flow direction (MD) of the film at 95 ° C. for 5 minutes is 3.0% or less. Here, if the hot water shrinkage rate of MD is 3.0% or less, it is possible to suppress the occurrence of troubles such as pitch deviation due to heat shrinkage in processes such as printing and laminating.

(4) The thickness variation rate in the width direction (TD) of the film is preferably 10% or less of the average thickness. Here, if the thickness variation rate is 10% or less of the average thickness, the occurrence of wrinkles due to thickness unevenness, the occurrence of tarmi, the misregistration of printing, the meandering of the film path and the deviation of the printing pitch, etc. The occurrence of trouble can be suppressed.

Hereinafter, a production method suitable for obtaining the surface-treated polyamide laminated film of the present invention will be described.
That is, using a polyamide-based resin as a raw material, a film that is substantially amorphous and not oriented (hereinafter referred to as “unstretched film”) is produced by a coextrusion method. This unstretched film is manufactured by, for example, employing a co-extrusion method in which the raw material is melted by 1 to 7 extruders, extruded from a flat die, and then rapidly cooled to form a flat unstretched film. Can do. The raw material to be supplied to the extruder may be pellets prepared by previously melting and kneading pellets of both the aliphatic polyamide resin (A) and the aromatic polyamide resin (B) in a biaxial kneader or the like. A mixed pellet obtained by simply dry blending the above pellets with a blender may be used.

Next, the unstretched film is stretched in the biaxial direction in terms of stretching effect, film strength, and the like in the film flow direction (MD) and the width direction (TD) which is the orthogonal direction.
As the biaxial stretching method, any conventionally known stretching method such as tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular simultaneous biaxial stretching, and the like can be adopted. For example, in the case of the tenter-type sequential biaxial stretching method, it is important that the unstretched film is heated to a temperature range of 50 to 110 ° C. and stretched 2.4 times or more in the longitudinal direction by a roll-type longitudinal stretching machine. .
Here, when the longitudinal stretching ratio is less than 2.4 times, stretching unevenness occurs, the thickness becomes non-uniform, or the strength of the film decreases due to insufficient orientation.

It is important that the longitudinally stretched film stretched by the above method is subsequently held at the end with a tenter clip and stretched by TD to 2.4 times or more in a temperature range of 60 to 140 ° C. by a tenter-type lateral stretching machine. It is.
Here, when the transverse draw ratio is less than 2.4 times, the transverse draw ratio is too low, and non-stretched portions such as unstretched portions are generated, resulting in uneven thickness and insufficient film orientation due to insufficient orientation. There is a problem of lowering.

The biaxially stretched film stretched by the above method continues to hold the end with a tenter clip, is 200 ° C. or higher in a tenter oven, and is 10 ° C. higher than the extrapolated melting start temperature of the aliphatic polyamide resin (A) described above. Heat fixation is performed at a temperature of 1 second to 2 minutes or less, preferably 1 second to 30 seconds, more preferably 3 seconds to 15 seconds. Here, when the heat setting temperature is lower than 200 ° C. or when the processing time is 1 second or less, the hot water shrinkage of MD cannot be suppressed to 3.0% or less, and printing, laminating, and the like. This causes problems such as shrinkage and shift in pitch. On the other hand, if the heat setting temperature exceeds 10 ° C. higher than the extrapolated melting start temperature of the aliphatic polyamide resin described above, or if the treatment time exceeds 2 minutes, the stress of melting or crystallization of the film during heat setting Breakage occurs due to the shortage of mechanical properties of the film.
The extrapolated melting start temperature described above is a straight line obtained by extending the low-temperature base line of the melting peak in the differential scanning calorimetry (DSC) described in JIS K 7121: 1987 to the high-temperature side. This is the temperature obtained from the intersection of the tangent lines drawn at the point where the gradient is maximum on the low temperature side curve.

The biaxially stretched film stretched by the above method is subsequently subjected to surface treatment by discharge treatment in an atmosphere having an inert gas concentration of 99% or more, an active gas concentration of 1% or less, and a reactive gas concentration of 1% or less on at least one surface. It is necessary to implement.

At this time, the higher the concentration of the inert gas, the better the laminate strength when wet, and it is necessary to be 99% or more, preferably 99.9% or more, more preferably 99.98% or more. However, when productivity and cost in the case of normal production are considered, oxygen, which is an active gas contained in the atmosphere to some extent, flows in as a carrier flow during processing. If the amount of inert gas blown is increased, the concentration of the active gas can be lowered, but the amount of inert gas used per product increases and the cost increases. For this reason, it is desirable to reduce the amount of the inert gas used within a range that is sufficiently effective in order to reduce costs. Further, if the amount of the inert gas blown is increased, exhaust may not be in time, in which case the oxygen concentration in the indoor atmosphere is lowered, and the operator may be deficient in oxygen. In order to maintain the oxygen concentration in the indoor atmosphere from the viewpoint of safety, it is realistic that the concentration of the inert gas is up to 99.999%.

On the other hand, the concentration of the active gas needs to be 1% or less, preferably 0.1% or less, more preferably 0.02% or less.
If the inert gas concentration is 99% or more and the active gas concentration is 1% or less, the laminate strength when the laminate film is wet is drastically improved, and 3.9 N / 15 mm or more can be achieved.

In the present invention, the inert gas refers to nitrogen, helium, neon, argon, krypton, etc., and is preferable from the viewpoint that nitrogen, argon, etc. can be obtained at low cost, and the surface treatment operation can be performed safely and smoothly. .
Further, in the present invention, the active gas refers to oxygen, carbon dioxide, carbon monoxide, ozone, etc., from the point that oxygen and carbon dioxide can be obtained at low cost, and the surface treatment operation can be performed safely and smoothly. preferable.
The inert gas and the active gas may be a mixture of a plurality of substances.

In order to further improve the laminate strength when wet, a reactive gas can be added in addition to the inert gas and the active gas. The addition amount of the reactive gas is preferably 1% or less from the viewpoint that the surface treatment operation can be performed safely and smoothly.
Furthermore, in the present invention, the reactive gas refers to hydrogen, ammonia, acetylene, methane, etc., and is preferable from the viewpoint that hydrogen and ammonia can be obtained at low cost and the surface treatment operation can be performed smoothly. The reactive gas may be a mixture of a plurality of substances.

The discharge treatment method is not particularly limited, and examples thereof include corona treatment, atmospheric pressure plasma treatment, and remote plasma treatment. Specifically, corona treatment and atmospheric pressure plasma treatment are preferable because they are simple and can perform the surface treatment operation safely and smoothly.

As an embodiment of the present invention, there is a surface-treated polyamide-based laminate film obtained by laminating a sealant film on the surface-treated surface of the surface-treated polyamide-based laminated film.
Examples of the laminate film include those in which a sealant film (layer) is disposed on at least one side surface on which the surface-treated polyamide-based laminate film has been subjected to surface treatment.

The sealant film may be any resin that can be heat-sealed, and generally includes a polyolefin-based resin, a polyester-based resin, and the like. Specifically, polypropylene, low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, ionomer Resins, ethylene / α-olefin copolymers, amorphous polyesters and the like may be mentioned, but are not limited thereto. The thickness of the sealant film is generally preferably about 15 to 100 μm. When the sealant film is thin, the sealing strength at the time of heat sealing tends to be inferior, whereas when it is too thick, it tends to be unsuitable for packaging applications.

Further, the method for laminating the surface-treated polyamide-based laminated film and the sealant film is not particularly limited, and examples thereof include a dry laminating method, a wet laminating method, and an extrusion laminating method. Specifically, a dry laminating method and an extrusion laminating method are usually used.

Furthermore, as another embodiment of the present invention, there is a bag made of the surface-treated polyamide-based laminate film. This is a secondary process of the above laminate film, and is obtained by heat-sealing sealant layers to form a bag. Examples of the contents of the bag include foods, pharmaceuticals, chemicals, and fragrances that do not want to be altered by oxygen. For applications that require higher wet laminate strength, such as when the weight of the contents is large, or for applications that require higher pressure than the inside, such as packaging for foods that undergo retort processing, airbag cushioning materials, etc. Are preferably used.

  Hereinafter, the contents and effects of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. The evaluation and measurement methods for the film were performed by the following methods.

(1) Laminate strength when wet
AD-900 manufactured by Toyo Morton Co., Ltd. as the main agent, CAT-RT85 manufactured by Toyo Morton Co., Ltd. as the curing agent, and ethyl acetate as the diluent solvent on the treated surface of the surface-treated polyamide-based laminated film formed by dry lamination . The mixture was mixed at 37.7%, 5.7%, and 56.6%, and after gravure coating was applied, it was dried at 80 ° C. to remove ethyl acetate, so that the adhesive coating amount was 3 g / m ² . LLDPE film manufactured by Tosero Corporation as a sealant U. After adhering 50 μm of X FCS at 90 ° C. by dry lamination, aging was performed at 40 ° C. for 3 days.

Lamination strength when wet after lamination The layer between the polyamide resin laminated film dry-laminated by the above method and the sealant is peeled off with tweezers using water or ethanol. When the peeled part becomes about 1 cm, a rappy tape (cemedine 18 mm width) is adhered in the longitudinal direction of the film so as to cover the peeled part. The film with the rappy tape is cut into strips with a width of 15 mm and a length of 100 mm in a direction perpendicular to the flow direction, and the peeled portion is expanded to about 50 mm while applying water. Both sides of the peeled film were gripped by an autograph (manufactured by Toyo Seiki) and pulled at a speed of 50 mm / min while water was applied to the peeled portion of the film. The initial peak value was measured at n = 5, and the average value was defined as the laminate strength when wet (N / 15 mm).
Measurement results When the laminate strength when wet is 3.9 N / 15 mm or more (◯),
If the laminate strength when wet is less than 3.9 N / 15 mm (×)

(2) Oxygen permeability (fmol / (m2 / sec / Pa))
Using an “OXY-TRAN100 type oxygen permeability measuring device” manufactured by Modern Control Co., Ltd., measured at a temperature of 25 ° C. and 50% RH (relative humidity 50%) (n = 3), and the average value obtained The following evaluation was performed by rounding off the first decimal place.
Those with an oxygen permeability of 80 fmol / (m 2 · sec · Pa) or less (○)
Those with oxygen permeability exceeding 80 fmol / (m 2 · sec · Pa) (×)

(3) Hot water shrinkage rate From the both ends of the obtained film and the central three points, cut into 120 mm in TD and 120 mm in TD, and draw three reference lines of about 100 mm in MD of this sample. This sample is left in an atmosphere of 23 ° C. and 50% RH for 24 hours, and the reference line is measured. The measured length before heat treatment is F. This sample is immersed in hot water maintained at 95 ° C., heated for 5 minutes, and then taken out. Further, after being left in an atmosphere of 23 ° C. and 50% RH for 30 minutes, the reference line is measured, and the length after the heat treatment is defined as G.
The hot water shrinkage rate is calculated by the following formula, and the average value of the three (rounded off the second decimal place of the average value) is the hot water shrinkage rate of MD, and the maximum of the three points at both ends and the center. The following evaluation was performed on the product.
Hot water shrinkage = [(F−G) / F] × 100 (%)
MDs with hot water shrinkage of 3.0% or less (○), those with more than 3.0% (×)

(4) Thickness fluctuation rate (%)
Using a striking-point thickness meter, the thickness is measured at intervals of 20 mm in the width direction of the obtained film, the maximum value at that time is Tmax, the minimum value is Tmin, the average value obtained by summing all the measurement points and dividing by the number of measurement points Tave.
The thickness fluctuation rate was calculated by the following formula (rounded to the first decimal place), and the following evaluation was performed.
Thickness variation rate = [(Tmax−Tmin) / Tave] × 100 (%)
Thickness fluctuation rate of 10% or less (○), 10% or more (×)

Example 1
As the aliphatic polyamide (A), nylon 6 “Mitsubishi Engineering Plastics Co., Ltd., trade name Novamid 1022C6, extrapolation melting start temperature: 215 ° C.” and MXD6 “Mitsubishi Gas Chemical Co., Ltd.” as the aromatic polyamide (B) ), Product name MX nylon S6007 "
(a) Aliphatic polyamide (A) as a layer,
(b) A layer obtained by mixing the aromatic polyamide (B) and the polyamide elastomer (PEBAX4033SA1 manufactured by Atofina) at a ratio (weight ratio) of 97: 3 by dry blend as a layer,
(c) As a layer, 80% by weight of aliphatic polyamide (A) and 20% by weight of aromatic polyamide (B) were mixed by dry blending, and each of three 65 mmφ extruders (L / D = 28) was mixed. And separately melted and kneaded at a set temperature of 260 ° C., and then the layers (a) and (c) were divided almost in half in each distribution block, and the layer structure was (a) / (c) / (B) / (c) / (a) is laminated in a co-extrusion T-die and extruded as a laminated film so as to have a five-layer structure, and is closely adhered to a cast roll at 30 ° C. and rapidly cooled. An unstretched laminated film having a thickness of 32 μm, a (c) layer of 19 μm, a (b) layer of 38 μm, a (c) layer of 19 μm, and a (a) layer of 32 μm was obtained.

The obtained unstretched laminated film was stretched 2.7 times in the longitudinal direction by a roll-type stretching machine under the condition of 60 ° C., and then the end of the longitudinally stretched film was held with a tenter clip. The film was stretched 3.4 times in the transverse direction under the condition of 100 ° C., and then heat-fixed at 215 ° C. for 6 seconds. The heat-fixed film was trimmed at both end portions corresponding to the clip holding portion. One side of the trimmed film was subjected to corona treatment in an atmosphere using nitrogen gas as the inert gas, nitrogen concentration of 99.9%, oxygen gas as the active gas, and oxygen concentration of 0.1%. . After the surface treatment, the film was wound into a roll and (a) / (c) / (b) / (c) / (a) = 3.5 μm / 2 μm / 4 μm / 2 μm / 3.5 μm 3 A laminated biaxially stretched film having a layer structure and an overall thickness of about 15 μm was obtained. The results of evaluation using the obtained surface-treated polyamide-based laminated film are shown in Table 1.

(Example 2)
A film was obtained in the same manner as in Example 1 except that the nitrogen concentration during the surface treatment was 99% and the oxygen concentration was 1%, and the same evaluation was performed. The results are shown in Table 1.

(Example 3)
A film was obtained in the same manner as in Example 1 except that the nitrogen concentration during the surface treatment was 99.995% and the oxygen concentration was 0.005%, and the same evaluation was performed. The results are shown in Table 1.

Example 4
A film was obtained in the same manner as in Example 1 except that the stretching ratio in the longitudinal direction was 2.4 times, and the same evaluation was performed. The results are shown in Table 1.

(Example 5)
A film was obtained in the same manner as in Example 1 except that the heat setting temperature after stretching was 200 ° C., and the same evaluation was performed. The results are shown in Table 1.

(Example 6)
A film was obtained in the same manner as in Example 1 except that the heat setting temperature after stretching was 225 ° C., and the same evaluation was performed. The results are shown in Table 1.

(Example 7)
A film was obtained in the same manner as in Example 1, except that the nitrogen concentration during the surface treatment was 99.8%, the oxygen concentration was 0.1%, and 0.1% of hydrogen was added as a reactive gas. Was evaluated. The results are shown in Table 1.

(Example 8)
A film was obtained in the same manner as in Example 1 except that the thickness of the layer (b) was changed to 2 μm, and the same evaluation was performed. The results are shown in Table 1.

(Comparative Example 1)
A film was obtained in the same manner as in Example 1 except that the nitrogen concentration during the surface treatment was 90% and the oxygen concentration was 10%, and the same evaluation was performed. The results are shown in Table 1.

(Comparative Example 2)
A film was obtained in the same manner as in Example 1 except that the stretching ratio in the longitudinal direction was 2.3 times, and the same evaluation was performed. The results are shown in Table 1.

(Comparative Example 3)
A film was obtained in the same manner as Example 1 except that the heat setting temperature after stretching was 190 ° C., and the same evaluation was performed. The results are shown in Table 1.

(Comparative Example 4)
In Example 1, the same method was used except that the heat setting temperature after stretching was 230 ° C., but the film was frequently broken in the tenter and could not be continuously formed. The results are shown in Table 1.

(Comparative Example 5)
A film was obtained in the same manner as in Example 1 except that the thickness of the layer (b) was 1 μm, and the same evaluation was performed. The results are shown in Table 1.

(Comparative Example 6)
A film was obtained in the same manner as in Example 1 except that the aliphatic polyamide (A) in layer (c) was 95 wt% and the aromatic polyamide (B) was 5 wt%, and the same evaluation was performed. The results are shown in Table 1.

From Table 1, it can be seen that Examples 1 to 8 which are the films of the present invention show good results for all the evaluation items. In particular, compared with Example 2 in which the nitrogen concentration during the surface treatment is 99% and the oxygen concentration is 1%, the other examples in which the nitrogen concentration during the surface treatment is 99.9% and the oxygen concentration is 0.1% are laminated. It was revealed that Example 3 in which the strength was excellent and the nitrogen concentration during the surface treatment was 99.995% and the oxygen concentration was 0.005% was further excellent in laminate strength. Moreover, it became clear that the laminate strength was more excellent in the other examples in which the longitudinal draw ratio was 2.7 times compared to Example 4 in which the longitudinal draw ratio was 2.4 times. Furthermore, in Example 7 in which the atmosphere during the surface treatment was such that the nitrogen concentration was 99.8%, the oxygen concentration was 0.01%, and the hydrogen gas was 0.01%, the surface treatment was performed without using hydrogen gas. It became clear that the laminate strength was superior to other examples.

On the other hand, Comparative Example 1 in which the nitrogen gas ratio during the surface treatment was as high as 90% was less effective for the surface treatment, and the laminate strength when wet was low. Comparative Example 2 having a low longitudinal stretching ratio was a film in which stretching unevenness occurred and the thickness variation rate was large. In addition, the laminate strength when wet was also low due to the effect of stretching unevenness. In Comparative Example 3 where the heat setting temperature is low, the hot water shrinkage rate of MD is large, so that there is a problem that troubles such as shrinkage due to shrinkage in printing, laminating, and the like are likely to occur. Furthermore, the laminate strength when wet was also low due to the effect of stretch orientation. In Comparative Example 4 having a high heat setting temperature, breakage occurred frequently in the tenter, and the film could not be continuously formed. (B) In Comparative Example 5, where the thickness of the layer is as thin as 1 μm, the oxygen permeability is as high as 160 fmol / (m 2 · sec · Pa), which is not suitable as a gas barrier packaging material. In Comparative Example 6 in which the aliphatic polyamide (A) in the layer (c) was 95% by weight and the aromatic polyamide (B) was 5% by weight, the laminate strength when wet was low.

Claims (11)

In a polyamide-based resin laminated film having a laminated structure including at least two layers of (a) a layer mainly composed of an aliphatic polyamide resin (A) and (b) a layer mainly composed of an aromatic polyamide resin (B) The laminate strength when the surface-treated surface is wet is 3.9 N, on which at least one surface of the film is subjected to surface treatment by discharge treatment in an atmosphere having an inert gas concentration of 99% or more and an active gas concentration of 1% or less. / 15 mm or more and a surface-treated polyamide-based laminated film having an oxygen permeability of 80 fmol / (m 2 · sec · Pa) or less under the condition of 25 ° C. × 50% RH. Between the (a) layer containing the aliphatic polyamide resin as a main component and the (b) layer containing the aromatic polyamide resin as a main component, 65-100% by mass of the aliphatic polyamide resin (A) and aromatic The surface-treated polyamide-based laminated film according to claim 1, comprising a (c) layer containing 0 to 35% by mass of the polyamide resin (B). The surface-treated polyamide-based laminated film according to claim 1 or 2, wherein the aliphatic polyamide polymer (A) is nylon 6 and the aromatic polyamide polymer (B) is polymetaxylylene adipamide. The surface-treated polyamide-based laminated film according to any one of claims 1 to 3, wherein a thickness of the (b) layer containing the aromatic polyamide resin as a main component is 2 to 7 µm. The surface-treated polyamide film according to any one of claims 1 to 4, wherein the inert gas is at least one gas selected from nitrogen, helium, neon, argon, and krypton. The hot water shrinkage rate in the film flow direction (MD) at 95 ° C for 5 minutes is 3.0% or less, and the thickness variation rate in the width direction (TD) of the film is 10% or less of the average thickness. To 5. The surface-treated polyamide-based laminated film according to any one of 5 to 5. 7. The surface-treated polyamide-based laminated film according to claim 1, wherein the atmosphere during the surface treatment is an inert gas concentration of 99% or more, an active gas concentration of 1% or less, and a reactive gas concentration of 1% or less. The surface-treated polyamide which consists of a multilayer structure in which the said surface treatment surface in the surface treatment polyamide-type laminated | multilayer film as described in any one of Claim 1 to 7 is arrange | positioned so that at least any one surface of a resin laminated body may be comprised. Laminated film. A surface-treated polyamide-based laminate film obtained by laminating a sealant film on the surface-treated surface of the surface-treated polyamide-based laminated film according to any one of claims 1 to 8. A bag comprising the surface-treated polyamide-based laminate film according to claim 9. After the step of stretching an unstretched film extruded from a flat die by a tenter-type sequential biaxial stretching method at a stretching ratio of 2.4 times or more for both MD and TD, the aliphatic polyamide polymer (A ) Extrapolated melting start temperature (measured in accordance with JIS K 7121) through a process of heat setting at a temperature not higher than 10 ° C., and at least one surface of the film has an inert gas concentration of 99% or more and an active gas A method for producing a surface-treated polyamide-based laminated film comprising a step of performing a surface treatment by an electric discharge treatment in an atmosphere having a concentration of 1% or less.