JP2002103446A - Method for producing biaxially oriented polyamide film, biaxially oriented polyamide film by the method, and laminated film using the polyamide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a biaxially oriented polyamide film which is excellent in gas-barrier properties and adhesion before and after boiling treatment, transparency and flexural fatigue resistance and can be used for a gas-barrier film. SOLUTION: A gas-barrier film, especially excellent in gas-barrier properties, is provided by a method in which a substantially unoriented polyamide film having the layer structure of A/B, A/B/A, or A/B/C is preheated with the use of a heating medium and then stretched by using a tenter driven by a linear motor method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas barrier property and a moisture-proof property which are important properties in packaging films for fresh foods, processed foods, pharmaceuticals, medical equipment, electronic parts, etc., and also to transparency and handleability. The present invention relates to a laminated film having excellent characteristics.

[0002]

2. Description of the Related Art In recent years, food packaging has been drastically changed due to changes in food distribution and eating habits, and the characteristics required for packaging films and sheets have become increasingly severe.

[0003] Temperature, moisture, oxygen,
Deterioration of the quality of products due to ultraviolet rays and the influence of microorganisms such as bacteria and mold is a serious problem not only in terms of sales but also in terms of food hygiene. As a method of preventing such quality deterioration, antioxidants and preservatives have been added directly to foods in the past, but in recent years, regulations on food additives have become stricter from the standpoint of consumer protection. Under such circumstances, the permeability of gas and water is low, and the quality of food as a food is not deteriorated by freezing, boiling, retorting, etc. The demand for packaging films is increasing.

[0004] That is, in the packaging of fish meat, animal meat, shellfish and the like, it is important to suppress the oxidation and alteration of proteins and oils and fats, and to maintain the taste and freshness. It is desirable to use it to block air permeation. Moreover, when wrapped in a gas barrier film, the fragrance of the contents is retained and the permeation of moisture is prevented, so that the moisture absorption of dried products is suppressed, and the deterioration and solidification due to evaporation of moisture is suppressed in the case of hydrated products. In addition, it is possible to maintain a fresh flavor during packaging for a long time.

For these reasons, kneaded products such as kamaboko, dairy products such as butter and cheese, miso, tea, coffee,
In a packaging film for confectionery such as ham / sausage, instant food, castella, biscuit, etc., the gas barrier properties and moisture resistance are extremely important properties.
These properties are not limited to food packaging films, but are also extremely important as medical products that need to be handled under aseptic conditions or packaging films for electronic components that require rust prevention.

As a film having excellent gas barrier properties,
Known are those in which a metal foil such as aluminum is laminated on a plastic film, and those in which vinylidene chloride or an ethylene vinyl alcohol copolymer is coated. Further, as a device using an inorganic thin film, a device in which a deposited film of silicon oxide, aluminum oxide, or the like is laminated is also known.

[0007] As a form actually used, a laminate of a polyamide film is provided by providing a sealant layer by a dry laminating method or a sealant layer by an extrusion laminating method on a printed layer and an adhesive. A bag is prepared using the laminate, the contents are filled, and the opening is heat-sealed. For example, seasonings such as miso and soy sauce, moisture-containing foods such as soups and retort foods, and chemicals are packaged. Offering to consumers.

The following problems have been pointed out in the above-mentioned conventional gas barrier films. Aluminum foil laminated as a gas barrier layer is excellent in economics and gas barrier properties, but is opaque, so the contents cannot be seen when packaged, and it does not transmit microwaves, so it can not be processed with a microwave oven .

Further, those coated with vinylidene chloride or ethylene vinyl alcohol copolymer do not have sufficient gas barrier properties against water vapor, oxygen and the like, and the performance is particularly deteriorated by high temperature treatment. In addition, there is a concern that vinylidene chloride may cause air pollution due to generation of chlorine gas at the time of incineration.

Therefore, a resin film having an inorganic vapor-deposited layer such as silicon oxide or aluminum oxide formed thereon as a gas barrier layer has been proposed. As a substrate film on which silicon oxide, aluminum oxide, or the like is deposited, a polyester film (PET) having good dimensional stability has been used.
As a structure, a laminated structure such as PET / deposited layer / adhesive layer / PET / adhesive layer / unstretched polypropylene (CPP) is generally used. Lack of strength is a problem.

On the other hand, PET / evaporated layer / adhesive layer / stretched nylon (ONY) / adhesive layer / unstretched polypropylene (CP
In the case of the laminated structure as in P), there is a problem that the gas barrier property after the boiling treatment or the retort treatment is deteriorated due to the shrinkage of the nylon.

Therefore, a film laminated with nylon having a reduced shrinkage during high-temperature hot water treatment (Japanese Patent Laid-Open No. 7-27657).
No. 1) has been proposed. However, since the number of films to be laminated increases, the manufacturing process and the process of transport and storage become complicated, resulting in poor economic efficiency, and the thicker film makes handling difficult, which is not practical.

On the other hand, a gas barrier film using a nylon film as a vapor deposition base material has been studied. However, the nylon film has a large dimensional change due to moisture absorption and heating, so that the barrier property is unstable, and particularly after a boiling treatment or a retort treatment. However, there arises a problem that the gas barrier property is deteriorated.

Therefore, as a measure for improving the gas barrier properties, a laminated film (JP-B-7-1264) using stretched nylon having a reduced shrinkage rate in advance by a heat treatment as a deposition base material.
No. 9) has been proposed. However, the manufacturing process and the transportation and storage processes become complicated, which is not practical. In addition, nylon having a small shrinkage ratio at the time of high-temperature treatment (in Japanese Patent Publication No. Hei 7-12649, the sum of absolute values of dimensional changes in the vertical and horizontal directions when heated at 120 ° C. for 5 minutes is 2% or less). Even so, excellent gas barrier properties cannot be maintained by boiling treatment, which is high-temperature hot water treatment.

Further, when a nylon film is used as a vapor deposition base material, if water infiltrates between the nylon film and the vapor deposition layer, the adhesive strength between the layers is significantly reduced, and when it is used as a packaging bag, it only causes breakage. It is thought that it leads to a decrease in gas barrier properties. As described above, it is pointed out that a gas barrier film having a laminated structure provided with an inorganic vapor-deposited layer such as silicon oxide or aluminum oxide does not always have sufficient strength, and that the gas barrier property deteriorates due to boiling treatment or retort treatment.

In addition, Japanese Patent Publication No. 51-48511 discloses a gas barrier film which is transparent, allows the contents to be seen through, and which can be applied to a microwave oven. A gas barrier film on which SiO ₂ is deposited has been proposed. However, a SiOx-based material having a good gas barrier property (x = 1.3 to 1.8)
The deposited film has a slightly brown color and cannot be said to be sufficient in quality as a transparent gas barrier film. Japanese Patent Application Laid-Open No. 62-101428 describes a device provided with an inorganic vapor-deposited layer mainly composed of aluminum oxide, which not only has insufficient gas barrier properties but also has a problem of bending resistance. is there.

Gas having boiling resistance and retort resistance
Al as a barrier layer_TwoO_Three・ SiO _TwoAs an example of the system
Some are proposed in Japanese Patent Application Laid-Open No. 2-194944.
Is Al_TwoO_ThreeAnd SiO_TwoThe gas
The formation of the rear layer is complicated and requires large-scale equipment
And Moreover, these inorganic thin films are used as gas barrier layers.
Film also achieves both gas barrier properties and flex resistance
From the point of view
I can't get it. That is, it provides excellent boiling resistance and retort resistance
Has a certain degree (for example, about 2,000 mm or more)
Thickness is required, whereas thicker film has bending resistance
Deteriorates and cannot withstand drop impact,
It has sufficient gas barrier properties and moisture proofing properties,
It has good retort properties and excellent bending resistance.
Gas barrier films that can withstand fire
However, it has not been proposed.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide excellent gas barrier properties and adhesion even at the initial stage and after the boil treatment, as well as transparency and bending fatigue resistance. To provide a biaxially oriented polyamide film used for a gas barrier film having excellent properties, a method for producing the same, and a laminated film using the same.

[0019]

Means for Solving the Problems In view of the above problems, the present inventors have assiduously studied and finally arrived at the present invention. That is, the object of the present invention is solved by the following means.

The method for producing a biaxially oriented polyamide film according to the present invention uses a heating medium to convert a substantially unoriented polyamide sheet having an A / B, A / B / A or A / B / C layer structure into a heating medium. Preheating and then stretching using a tenter driven by a linear motor method. The polyamide resin composition used for the layer A is obtained by blending a composition consisting of X and Y shown below, or a composition consisting of X alone, and the polyamide resin composition used for the layer B is a composition consisting of Y alone. Product, a composition composed of Y and X, a composition composed of Y and Z, or a composition composed of any one of compositions composed of X, Y, and Z, and a polyamide resin composition used for the C layer, It consists of a composition consisting of X and / or Y. (X): Aromatic polyamide resin component composed of terephthalic acid and aliphatic diamine or adipic acid and meta-xylylenediamine (a) and aliphatic polyamide resin or aromatic polyamide resin composed of isophthalic acid and aliphatic diamine (b) A resin composition containing 10 mol% or more of the aromatic polyamide resin component (a) in a mixture and / or copolymer of (Y): an aliphatic polyamide resin (Z): a flex fatigue resistance improving agent In some cases, the polyamide resin composition used for the A layer or the A layer and the C layer is obtained by blending 50 to 100 parts by weight of the X and 50 to 0 parts by weight of the Y, and the polyamide used for the B layer. When the resin composition has the X in the range of 0 to 10
Parts by weight, the Y is 80-100 parts by weight, and the Z is 0-1.
It is preferable that the composition be obtained by mixing 0 parts by weight. In this case, the unoriented polyamide sheet is preheated by a heating medium to a glass transition temperature (Tg) of −10 ° C. or higher and a low temperature crystallization temperature (TC) of + 10 ° C. or lower,
Next, it is introduced into the tenter driven by the linear motor system,
Tg-20 ° C. between the pre-heating treatment and the tenter.
It is preferable to convey the unoriented polyamide sheet preheated without cooling below. Furthermore, in this case, it is preferable that the tenter simultaneously and simultaneously biaxially stretch 3.0 to 5.0 times in the vertical and horizontal directions. Furthermore, in this case, it is preferable that after the simultaneous biaxial stretching in the tenter, a relaxation treatment of 20% or less in the longitudinal direction and / or the transverse direction is performed. Furthermore, in this case, the biaxially oriented polyamide film obtained by the above production method is preferable. Furthermore, in this case, a laminated film in which an inorganic vapor-deposited layer and then a heat seal layer are laminated on at least one surface of the biaxially oriented polyamide film in this order is preferable. Further, in this case, it is preferable to laminate an anchor coat layer between the biaxially oriented polyamide film and the inorganic vapor deposition layer. Further, in this case, it is preferable that the inorganic vapor-deposited layer is a thin film layer of silicon oxide, aluminum oxide, or a mixture of silicon oxide and aluminum oxide.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each layer constituting material specified in the present invention will be described in detail, and the reason for defining the above characteristics will be described in detail.

In the present invention, the biaxially oriented polyamide film constituting the base layer is A / B (two kinds of two layers) or A / B.
It is necessary to have a configuration of B / A (two types and three layers) or A / B / C (three types and three layers). In terms of curls,
The A / B / A configuration that is the target layer configuration is preferable.

The thickness ratio of each layer of the biaxially oriented polyamide film is preferably 5 to 50%, more preferably 10 to 40%, particularly preferably 12 to 40% for the A layer or the A layer and the C layer. 35%. Two types and three layers A
In the case of the / B / A configuration, the thickness ratio of the surface A layer described above means the sum of the thickness ratios of both surface layers, and the three types of three layers A /
In the case of the B / C configuration, the above-described thickness ratio of the surface layers A and C means the sum of the thickness ratios of both surface layers. Layer A,
Or, when the thickness ratio of the A layer and the C layer is less than 5%, the dimensional stability becomes insufficient and the oxygen permeability deteriorates, which is not preferable. On the other hand, when the thickness ratio of the A layer or the A layer and the C layer exceeds 50%, the bending fatigue resistance deteriorates and the number of pinholes increases, which is not preferable.

The polyamide resin composition used for the layer A preferably contains a composition consisting of X and Y shown below or a composition consisting of X alone, and the polyamide resin composition used for the layer B May contain any one of a composition consisting of Y alone, a composition consisting of Y and X, a composition consisting of Y and Z, or a composition consisting of X, Y and Z. Preferably, the polyamide resin composition used for the C layer is a composition comprising X and / or Y.

X is an aromatic polyamide resin component (a) comprising terephthalic acid and an aliphatic diamine or adipic acid and meta-xylylenediamine and an aliphatic polyamide resin or an aromatic polyamide resin comprising isophthalic acid and an aliphatic diamine A mixture and / or copolymer of (b),
The resin composition contains the aromatic polyamide resin component (a) in an amount of 10 mol% or more. Further, Y is an aliphatic polyamide-based resin, and Z is a flex fatigue resistance improving agent.

The polyamide resin composition used for the layer A or the layers A and C preferably contains 50 to 100 parts by weight of X and 50 to 0 parts by weight of Y. It is preferable that the polyamide resin composition used for X is mixed with 0 to 10 parts by weight of X, 80 to 100 parts by weight of Y, and 0 to 10 parts by weight of Z.

Examples of the aliphatic polyamide used in the present invention include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 612, nylon 46, and copolymers and blends thereof. However, nylon 6 and nylon 66 are preferred. In addition, these polyamides may contain small amounts of known substances having known effects such as various anti-blocking agents, antistatic agents and stabilizers within a range not to impair their properties.

The flex fatigue resistance improver used in the present invention includes elastomers such as block polyesteramide, block polyetheramide, polyetheresteramide elastomer, polyester elastomer, modified ethylene propylene rubber, and modified acrylic. / Acrylate copolymer and the like, and these can be mixed and blended.

The feature of the method for producing a biaxially oriented polyamide film in the present invention is that the method for producing a biaxially oriented polyamide film serving as a base film is characterized by A / B, A / B
Preliminary heating of a substantially unoriented polyamide sheet having a layer configuration of / A or A / B / C is performed using a heating medium, and then simultaneous biaxial stretching is performed using a tenter driven by a linear motor system. Stretching, followed by heat setting, including relaxation in the machine and / or transverse directions.

More specifically, a substantially unoriented polyamide sheet is heated to a temperature of at least Tg-10 ° C.
Preheat to c + 10 ° C or less, then Tg-20 ° C
Without cooling, a tenter driven by a linear motor system is then used to simultaneously and biaxially stretch 3.0 to 5.0 times in the machine and transverse directions, and then in the machine direction and / or This is to perform heat setting including a relaxation treatment of 20% or less in the lateral direction. As the heating medium, a known heating medium such as hot air, a heating roll, or infrared radiation may be used.

Hereinafter, a method for producing a biaxially oriented polyamide film serving as a base material of the laminated film of the present invention will be described in detail. First, the A / B, the A / B / A, or the A
In forming a substantially unoriented polyamide sheet having a layer constitution of / B / C, the polymers constituting each layer are melted using a separate extruder, co-extruded, and cast from a die on a rotating drum. And a method of obtaining a polyamide sheet by rapid cooling and solidification, a method of laminating polymers constituting each layer by lamination, a method of combining these, and the like. This polyamide sheet is in a substantially unoriented state.

The unstretched polyamide sheet is first preheated to a temperature of Tg−10 ° C. or more and Tc + 10 ° C. or less using a heating medium. The heating temperature is preferably Tg to Tc. When the heating temperature is lower than Tg−10 ° C., the preliminary heating effect does not appear, and when the heating temperature is Tc + 1.
If the temperature exceeds 0 ° C., thermal crystallization proceeds, and in the stretching in the longitudinal direction and the transverse direction in a tenter driven by a linear motor system described later, the stretching stress increases, which is not preferable because it leads to breakage.

The pre-heated unoriented polyamide sheet is subsequently conveyed to a tenter driven by a linear motor system, which will be described later. One of the features of the present invention is how the sheet temperature during that time is controlled. It is. That is, the sheet between the preheating and the tenter driven by the linear motor system is kept warm rather than forcibly cooled, and for preheating or stretching in the longitudinal and lateral directions in the tenter. Is also used for heating. If the sheet is forcibly cooled and then reheated for stretching the tenter in the machine and transverse directions, thermal crystallization remarkably progresses, the stretching stress increases, and breakage occurs frequently, which is not preferable. Thermal crystallization also proceeds in this heat retaining section where the temperature is not cooled to Tg-20 ° C. or lower, but does not pose a practical problem much slower than the aforementioned forced cooling and reheating.

Using a tenter driven by a linear motor, the unoriented polyamide sheet obtained in this manner was heated at a temperature of from Tg to a melting point (Tm) of less than −20 ° C. in a longitudinal direction and a transverse direction, respectively. Stretching is performed so as to be 0.0 to 5.0 times. Preferably, the stretching temperature is Tg to Tm-40 ° C, and the stretching ratio is 3.2 times or more in both the longitudinal and transverse directions. If the stretching temperature is too low, the stretching stress increases significantly and breakage frequently occurs, which is not preferable. If the temperature exceeds Tg-20 ° C, the thickness unevenness increases, and thermal crystallization remarkably progresses, the stretch stress increases, and the breakage increases. Frequent and undesirable. As for the draw ratio, unless the draw ratio in the longitudinal direction and / or the transverse direction is 3.0 times or more, the strength in each draw direction becomes low, which is not preferable, and the draw ratio in the longitudinal direction and / or the transverse direction is 5.0. If it exceeds twice, the stretching stress in each direction will increase remarkably and breakage will occur frequently, which is not preferable.

The thus-obtained biaxially oriented polyamide film is subsequently heat-set by using the same tenter, including a relaxation treatment of not more than 20% in the vertical and / or horizontal directions. Preferably, a relaxation treatment of 5 to 15% is performed in the vertical direction and / or the horizontal direction. Without mitigation,
Changes in moisture absorption dimensions, changes in dry heat dimensions, and changes in boil dimensions are remarkably large, and cause troubles such as bag-making curl during the post-processing step and due to dimensional changes in the post-processed product. If it exceeds, the residual stress stretched in the longitudinal direction and / or the transverse direction cannot be absorbed in the heat setting step, and the substantial relaxation effect does not appear, and the film is loosened in the tenter. This is not preferable because it causes breakage and scratches on the film.

As described above, the A / B and the A / B /
A, or a substantially unoriented polyamide sheet having the layer structure of A / B / C is preheated by using a heating medium, and then is simultaneously biaxially stretched by using a tenter driven by a linear motor system. A biaxially oriented polyamide film, which becomes a base layer of a laminated film having excellent gas barrier properties and moisture resistance, is economically obtained by stretching and subsequently performing heat setting including relaxation treatment in the longitudinal direction and / or the transverse direction. Can be.

The following can be considered as a reason for obtaining the above-mentioned effect. By preheating the unoriented polyamide sheet, the sheet surface receives a heat history and the thermal crystallization is appropriately promoted, and the surface crystallization of the obtained biaxially oriented polyamide film is promoted. It is considered that the moisture absorption property of the film is reduced, and the change in the moisture absorption dimension and the change in the boil dimension are reduced, thereby maintaining the gas barrier property and moisture proof property of the inorganic vapor-deposited layer. By keeping the temperature, the crystallization promoting action due to the hydrogen bond specific to the polyamide generated at the time of reheating from forced cooling is prevented, and the formation of the orientation that is developed during stretching in the longitudinal direction and the transverse direction with the tenter is facilitated,
By simultaneously stretching in the machine direction and the transverse direction, it is possible to further prevent the crystallization-promoting action due to the hydrogen bond specific to the polyamide, thereby improving the stretchability. In addition, by simultaneously stretching in the vertical and horizontal directions, it is easy to make the orientation isotropic, and the change in the moisture absorption dimension or the change in the boil dimension becomes isotropic in the vertical and horizontal directions. It can be dispersed to maintain gas barrier properties and moisture-proof properties.
In addition, by using the same tenter and performing heat setting including relaxation treatment in the vertical and / or horizontal directions, it is possible to produce a film with low shrinkage while maintaining surface flatness,
The change in the moisture absorption or the change in the size of the boil is reduced, the change in the size of the inorganic vapor deposition layer is also reduced, and the gas barrier property and moisture resistance can be maintained. For the reasons described above, the stretchability is improved, and a gas barrier laminate film with less operation trouble can be economically provided.

Next, examples of the inorganic vapor-deposited layer constituting the gas barrier layer include silicon oxide, aluminum oxide oxide, magnesium oxide, and mixtures thereof. The term “silicon oxide” used herein refers to a mixture of various silicon oxides such as SiO and SiO ₂ , and the term “aluminum oxide” refers to AlO or A
a mixture of various aluminum oxides such as l ₂ O ₃ ,
The amount of oxygen bonded in each oxide varies depending on the manufacturing conditions.

Particularly, a mixture of aluminum oxide and silicon oxide is preferable as the gas barrier layer in the present invention because of its excellent transparency and bending resistance. Further, a mixture of silicon oxide and aluminum oxide in which the content of aluminum oxide in the gas barrier layer is 5% by weight or more and 45% by weight or less is preferable.

When the amount of aluminum oxide in the silicon oxide / aluminum oxide-based vapor-deposited film is less than 5% by weight, there arises a problem that lattice defects occur in the vapor-deposited film and a sufficient gas barrier property cannot be obtained. When the amount of aluminum oxide in the aluminum oxide-based vapor-deposited film exceeds 45% by weight, the flexibility of the film is reduced, and the film is easily broken (cracked or peeled) due to a dimensional change during hot water treatment, and the barrier property is reduced. This causes a problem such as lowering, which does not meet the purpose of the present invention. A more preferred ratio of aluminum oxide is
10 to 35% by weight, more preferably 15% by weight
Not less than 25% by weight. The gas barrier layer may further contain a small amount (up to 3% by weight) of other oxides and the like as long as the characteristics are not impaired.

The thickness of the gas barrier layer composed of silicon oxide and aluminum oxide is usually from 10 to 5,000 °, preferably from 50 to 2,000 °, and if the thickness is less than 10 °, satisfactory gas barrier properties can be obtained. Difficult, 5,0
Even if the thickness is excessively larger than 00 °, the corresponding effect of improving the gas barrier property cannot be obtained, which is rather disadvantageous in terms of bending resistance and manufacturing cost.

For the production of the silicon oxide / aluminum oxide based deposited film, a physical vapor deposition method such as a vacuum deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method such as a CVD method is appropriately used. For example, when a vacuum deposition method is employed, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is used as a deposition material.
Heating can be performed by resistance heating, induction heating, electron beam heating, etc. In addition, oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc. are introduced as a reaction gas, ozone addition, ion assist, etc. It is also possible to employ reactive vapor deposition using the above means. Further, the film formation conditions such as applying a bias to the substrate, heating and cooling the substrate, and the like can be arbitrarily changed. The above-mentioned deposition material, reaction gas,
Substrate bias, heating / cooling, etc.
The same can be applied to the case where the VD method is adopted.

Before or during the vapor deposition, the surface of the polyamide resin film serving as the base layer is subjected to a corona treatment, a flame treatment, a low-temperature plasma treatment, a glow discharge treatment, a reverse sputtering treatment, a surface roughening treatment, etc. It is also effective to improve the adhesion strength of the film. By using a silicon oxide / aluminum oxide-based thin film having such a component composition, it is possible to obtain a gas barrier film that is transparent and has excellent performance that can withstand a boiling treatment and a gelbo test (bending resistance test).

The gas barrier properties of the laminated film according to the present invention are greatly related to the adhesion strength between the polyamide resin film serving as the base layer and the gas barrier layer, and the gas barrier properties improve as the adhesion strength increases. According to the examination results of the present inventors, in order to have excellent gas barrier properties and maintain the excellent gas barrier properties even after the boiling treatment, the adhesion strength after the boiling treatment is 1000 m
It has been confirmed that it should be N / 15 mm or more.
More preferred adhesion strength is 1500 mN / 15 mm or more,
It is more preferably at least 2,000 mN / 15 mm, more preferably at least 2500 mN / 15 mm. When the adhesion strength is less than 1000 mN / 15 mm, the boiling treatment tends to deteriorate the gas barrier properties.

The reason for this is considered that if the adhesion strength is high, the inorganic vapor deposition layer is less likely to be peeled off even when the vapor deposition base material slightly shrinks due to boiling treatment or retort treatment.

Means for obtaining such excellent adhesion strength include a corona treatment, a plasma treatment, a glow discharge treatment, a reverse sputtering treatment, and a roughening treatment on the surface of a polyamide resin film which is a base layer of an inorganic vapor deposition layer. Processing, etc.
Alternatively, there is a method of forming an anchor coat layer on a polyamide-based resin film for improving adhesion, but of course, the method is not limited to these methods.

The anchor coating agent preferably used for improving the adhesion strength includes a reactive polyester resin, an oil-modified alkyd resin, a urethane-modified alkyd resin,
Melamine-modified alkyd resin, epoxy cured acrylic resin, epoxy resin (using amine, carboxyl group-terminated polyester, phenol, isocyanate, etc. as curing agent), isocyanate resin (amine, urea, carboxylic acid, etc. as curing agent) ), Urethane-polyester resin, polyurethane resin, phenol resin, polyester resin, polyamide resin, reactive acrylic resin, vinyl acetate resin, vinyl chloride resin and the like and copolymers thereof. These can also be used as aqueous resins solubilized and dispersed in water. In addition, it is also effective to use an inorganic coating agent such as a silane coupling agent as the anchor coating agent.

The method for forming the anchor coat layer is as follows.
Either an in-line method of applying at the time of producing the polyamide-based resin film or an off-line method of applying at a separate step from the production of the polyamide-based resin film can be adopted. For the coating, a known coating method, for example, a roll coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, a gravure coating method, an impregnation method, a curtain coating method, or the like can be adopted.

According to the study results of the present inventors, in order to improve the adhesion strength between the base layer and the inorganic vapor-deposited layer by forming the anchor coat layer, it is preferable to use an aqueous polyester resin from the viewpoint of cost and hygiene. . Such a polyester resin is obtained by polycondensing a dicarboxylic acid or a tricarboxylic acid with a glycol. Examples of the components used for the polycondensation include acid components such as terephthalic acid, isophthalic acid, adipic acid, and trimellitic acid, and glycol components such as ethylene glycol, neopentyl glycol, butanediol, and ethylene glycol-modified bisphenol A. However, of course, it is not limited to these. The polyester resin may be obtained by graft copolymerization of an acrylic monomer.

The preferred thickness of the anchor coat layer is 0.01 to 10 μm, more preferably 0.02 to 5 μm
If the thickness is less than 0.02 μm, the effect of improving the adhesion strength tends to be hardly exhibited, and if the thickness is more than 5 μm, the effect of improving the adhesion is not further exhibited. Also disadvantageous.

On the surface of the above-mentioned inorganic vapor-deposited layer, a heat seal layer made of a polyolefin-based resin for providing thermal adhesiveness is formed as a main purpose, and the heat seal layer serves as a protective layer for the inorganic vapor-deposited layer. It also has functions,
In order to effectively perform the function, it is extremely effective to increase the adhesive strength between the inorganic vapor-deposited layer and the heat seal layer. As a means for this, an adhesive layer is provided between the inorganic vapor-deposited layer and the heat seal layer. Is extremely effective.

The polyolefin resin constituting the heat seal layer is not necessarily required to be a single layer, but may be a multilayer. The resin constituting each layer when forming a multilayer structure is also
Not only a combination of resins of the same kind but also a laminate of a copolymer, a modified product, a blend, or the like of different polymers. For example, in order to enhance the laminating property and the heat sealing property, a polymer having a glass transition temperature (Tg) or a melting point lower than that of the thermoplastic polyolefin resin as a base is compounded, and in order to impart heat resistance, the Tg or the melting point is decreased. It is also possible to composite high polymers.

The polyolefin resin constituting the heat seal layer may contain various additives as necessary, such as a plasticizer, a heat stabilizer, an ultraviolet absorber, an antioxidant, a coloring agent, a filler, an antistatic agent, It is also possible to blend antibacterial agents, lubricants, antiblocking agents, other resins, and the like.

Particularly preferred as the resin constituting the adhesive layer is a resin having a glass transition temperature in the range of -10 ° C. to 40 ° C., such as a polyurethane resin, a polyester resin, an epoxy resin, a vinyl chloride resin, and acetic acid. Vinyl resins, polyethylene resins, polypropylene resins, melamine resins, acrylic resins, etc., which can be used alone or, if necessary, in combination of two or more, or by melting and mixing, or Examples of the group include a carboxylic acid group, an acid anhydride, (meth) acrylic acid and (meth) acrylic acid.
An adhesive composition containing a compound having an acrylate ester skeleton; an epoxy compound containing a glycidyl group or a glycidyl ether group; a curing agent or a curing accelerator having a reactive functional group such as an oxazoline group, an isocyanate group, an amino group, or a hydroxyl group. It is also effective to use.

The lamination of the polyolefin resin is formed as a heat-sealing layer on the inorganic vapor-deposited layer by a dry lamination method or a wet lamination method using an adhesive, or further by a melt extrusion lamination method or a co-extrusion lamination method. You.

The thus obtained gas-barrier laminated film or sheet of the present invention has excellent gas-barrier properties and gas-barrier durability by boiling or retorting.
Taking advantage of secondary processing characteristics, miso, pickles, side dishes, baby food, tsukudani, konjac, chikuwa, kamaboko,
Processed marine products, meatballs, hamburgers, genghis khan, ham, sausage, other processed meat products, tea, coffee, tea, bonito, kelp, potato chips, butter peanuts and other oil confections, rice crackers, biscuits, cookies, cakes, It can be effectively used for packaging such as buns, castella, cheese, butter, cut rice cake, soup, sauce, ramen, wasabi, and toothpaste. It can also be effectively used for packaging of industrial materials such as medical, electronic, chemical and mechanical such as precision material packaging. The form of the packaging material is not particularly limited, and can be widely applied to bags, lid materials, cups, tubes, standing packs, and the like.

[0057]

Next, the present invention will be described in detail with reference to examples. The present invention is naturally not limited by the following examples, and it is of course possible to implement the present invention with appropriate modifications within a range that can be adapted to the spirits of the preceding and the following. Is included. Also,
Various performance tests employed in the following Examples were performed by the following methods.

(1) Oxygen permeability: Measured at a humidity of 0% and a temperature of 25 ° C. using an oxygen permeability measuring device (“OX-TRAN 10 / 50A” manufactured by Modern Controls).

(2) Water Vapor Permeability: Measured at a humidity of 0% and a temperature of 25 ° C. using a water vapor permeability measuring device (“PERMATRAN” manufactured by Modern Controls).

(3) Adhesion strength: The laminated product was peeled 180 ° by using “Tensilon UTM2” manufactured by Toyo Sokki Co., Ltd. while adhering water to the interface, and the SS curve between the gas barrier layer and the base material was measured. Measured and determined.

(4) Flex fatigue resistance test: The flex fatigue resistance test (hereinafter, Gerbo test) was evaluated using a gelbo flex tester manufactured by Rigaku Corporation. The condition is (MI
LB131H) DE 112 inch × 8 inch test piece was made into a cylindrical shape having a diameter of 3 (、) inch, both ends were held, the initial grasping interval was 7 inches, and 3 (1/1) of the stroke
2) Add a 400 degree twist in inches. This operation is repeated 1000 times at a speed of 40 times / min. The measurement atmosphere is 20 ° C. and the relative humidity is 65%. The number of pinholes at this time was counted.

(5) Glass transition temperature (Tg) and low-temperature crystallization temperature (Tc): A non-oriented polyamide sheet is frozen in liquid nitrogen, decompressed and thawed, and heated at a rate of 10 ° C./min using a DSC manufactured by Seiko Denshi. The Tg and Tc of the unoriented polyamide sheet were estimated by evaluating and averaging the Tg and Tc of each laminated polyamide sheet, respectively, from the obtained endothermic heat curves.

(6) Film temperature: The temperature in the longitudinal stretching was measured using a radiation thermometer IR-004 manufactured by Minolta Co., Ltd.

(7) Film forming condition: Simultaneous biaxial stretching was performed for 2 hours under the same conditions, and the number of breaks was examined.

Example 1 35 parts by weight of nylon 6 and a nylon 6T / nylon 6 copolymer (copolymerization ratio 56/4)
6) 65 parts by weight of the mixture, 100 parts by weight of nylon 6 as a B layer were laminated from a T-die in an A / B / A configuration such that the thickness ratio (%) of the configuration was 15/70/15. While extruding while melting, apply a DC high voltage, electrostatically adhere to a rotating drum at 20 ° C, cool and solidify to a thickness of 205μ.
m unoriented polyamide sheet was obtained. Tg of this sheet
Was 47 ° C and Tc was 78 ° C.

The sheet was preheated by using a ceramic heater to a sheet temperature of 53 ° C., and then kept at 45 ° C., while continuously guiding the sheet to a tenter driven continuously by a linear motor system. Simultaneous biaxial stretching was performed at 130 ° C. to be 3.4 times in the machine direction and 4.0 times in the transverse direction, and then at 215 ° C., 6% in the machine direction,
After a relaxation treatment of 8% in the lateral direction, the film was cooled, and both edges were cut off to obtain a base layer biaxially oriented polyamide film having a thickness of 15 μm. Table 1 shows the film forming situation characteristics at this time.
Shown in At the same time, the above-mentioned water-dispersed graft polyester resin was coated at about 0.1 μm.

This film was excellent in both bending fatigue resistance and adhesiveness. This film is sent to a vacuum evaporation apparatus, and the inside of the chamber is maintained at a pressure of 1 × 10 ⁻⁵ Torr, and a mixed oxide of SiO ₂ : 70% by weight and Al ₂ O ₃ : 30% by weight is evaporated by electron beam heating of 15 Kw. Let it be 200mm thick
Was deposited on the coating surface to form an inorganic vapor-deposited layer. Next, on this inorganic vapor-deposited layer, unstretched polyethylene (thickness: 55
μm) was dry-laminated using an adhesive (“A310 / A10” manufactured by Takeda Pharmaceutical Co., Ltd., application amount 2 g / m ² ), and aged at 45 ° C. for 4 days to obtain a laminated film.

(1) Oxygen permeability of untreated film (cc / m ² · atm · day) (2) Oxygen permeability of film after immersion in hot water of 95 ° C. for 30 minutes and left for 1 hour Permeability (cc / m ² · atm · day) (3) After immersion in hot water at 95 ° C for 30 minutes, and left for 1 hour, the water vapor permeability of the film (g / m ² · day) (4) After immersion in hot water for 30 minutes, the adhesion force (g / 15 mm) when water was dropped onto the peeling interface of the film after standing for 1 hour (5) The number of pinholes (pieces) after the bending fatigue test was measured.
Further, the biaxially oriented polyamide film of the base layer was subjected to simultaneous biaxial stretching under the same conditions for 2 hours under the same conditions as (6) film forming conditions, and the number of breaks was examined.

(Example 2) A biaxially oriented polyamide film and a laminated film of a base layer were obtained in the same manner as in Example 1 except that preheating was performed so that the sheet temperature was 65 ° C using a ceramic heater.

Example 3 A biaxially oriented polyamide film of a base layer and a laminated film were obtained in the same manner as in Example 1 except that the stretching ratio in the longitudinal direction was 3.7.

(Example 4) A biaxially oriented polyamide film and a laminated film of a base layer were obtained in the same manner as in Example 1 except that relaxation treatment of 10% in the vertical direction and 12% in the horizontal direction were performed.

(Example 5) As layer A, a mixture of 30 parts by weight of nylon 6 and 70 parts by weight of a nylon 6T / nylon 5 copolymer (copolymerization ratio: 60/40) was used, and as layer C, 20 parts by weight Parts of nylon 6 and 80 parts by weight of MXD-6
Using a mixture, A / B / C thickness ratio (%) 15/70
A biaxially oriented polyamide film and a laminated film of a base layer were obtained in the same manner as in Example 1 except that the structure was / 15.

(Comparative Example 1) A biaxially oriented polyamide film and a laminated film of a base layer were obtained in the same manner as in Example 1 except that preheating using a ceramic heater was not performed.

Comparative Example 2 A laminated film was produced in the same manner as in Example 1 except that the sheet was pre-heated using a ceramic heater, rapidly cooled to 20 ° C., and led to a tenter. Since many breaks occurred during the production of the oriented film, a laminated film could not be obtained.

Comparative Example 3 An attempt was made to produce a laminated film in the same manner as in Example 1 except that the transverse stretching ratio was 5.3 times. However, many fractures occurred during the production of the biaxially oriented film. A laminated film could not be obtained.

Comparative Example 4 A biaxially oriented polyamide film and a laminated film of a base layer were obtained in the same manner as in Example 1 except that 100 parts by weight of nylon 6 was used as the A layer. The Tg of the obtained unoriented polyamide sheet was 4
0 ° C. and Tc were 68 ° C.

[0077]

[Table 1]

[0078]

According to the production method of the present invention, no breakage occurs
A biaxially oriented polyamide film suitable for use as an excellent gas barrier film that not only has excellent gas barrier properties but also retains its excellent gas barrier properties after boil treatment and can also have pin hole resistance Can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 101: 00) C08L 101: 00) B29K 77:00 B29K 77:00 105: 20 105: 20 B29L 9: 00 B29L 9:00 F term (reference) 4F100 AA01D AA19D AA20D AK47A AK47B AK47C AK48A AK48B AK48C AL01A AL01C AL05A BA02 BA03 BA05 BA06 BA10A BA10C BA10E BA13 BA16 BA25 CA30BJ03 EB03 GB03 EB03 GB03 EB03 GB03 JL12E JN01 YY00A YY00B YY00C 4F210 AA29 AB01 AD05 AD29 AG03 AK01 AP20 QA02 QC07 QG01 QG15 QG18 QL03 QW12 QW34 4J002 BB073 BB153 BB203 BG003 CF003 CL011 CL031 CL032 CL083 GF00

Claims (9)

[Claims] 1. A / B, A / B / A, or A / B / C
Production of a biaxially oriented polyamide film, characterized in that a substantially unoriented polyamide sheet having a layer structure of the above is preliminarily heated using a heating medium and then stretched using a tenter driven by a linear motor method. Method. The polyamide resin composition used for the layer A is obtained by blending a composition consisting of X and Y shown below, or a composition consisting of X alone, and the polyamide resin composition used for the layer B is a composition consisting of Y alone. Product, a composition composed of Y and X, a composition composed of Y and Z, or a composition composed of any one of compositions composed of X, Y, and Z, and a polyamide resin composition used for the C layer, It consists of a composition consisting of X and / or Y. (X): Aromatic polyamide resin component composed of terephthalic acid and aliphatic diamine or adipic acid and meta-xylylenediamine (a) and aliphatic polyamide resin or aromatic polyamide resin composed of isophthalic acid and aliphatic diamine (b) A resin composition containing the aromatic polyamide resin component (a) in an amount of 10 mol% or more in a mixture and / or copolymer of (Y): an aliphatic polyamide resin (Z): a flex fatigue resistance improving agent 2. The method for producing a biaxially oriented polyamide film according to claim 1, wherein the polyamide resin composition used for the A layer or the A layer and the C layer is such that the X ranges from 50 to 1.
00 parts by weight, obtained by mixing 50 to 0 parts by weight of the Y,
When the polyamide resin composition used for the B layer is such that X is 0
A method for producing a biaxially oriented polyamide film, which is obtained by mixing 10 to 10 parts by weight, 80 to 100 parts by weight of Y, and 0 to 10 parts by weight of Z. 3. The method for producing a biaxially oriented polyamide film according to claim 1, wherein the heating medium comprises:
The unoriented polyamide sheet is treated with a glass transition temperature (T
g) Preheating to a temperature of -10 ° C or higher and a low temperature crystallization temperature (TC) of + 10 ° C or lower, and then introducing into a tenter driven by a linear motor system, and a Tg-20 between the tenter after the preheating treatment and the tenter. A method for producing a biaxially oriented polyamide film, comprising transporting the unoriented polyamide sheet that has been preheated without being cooled to a temperature of not more than ° C. 4. The method for producing a biaxially oriented polyamide film according to claim 1, wherein the tenter has a simultaneous length of 3.0 to 5.0 times in the vertical and horizontal directions. A method for producing a biaxially oriented polyamide film, comprising biaxially stretching. 5. The method for producing a biaxially oriented polyamide film according to claim 1, wherein the tenter is simultaneously biaxially stretched and then stretched in a longitudinal direction and / or a transverse direction by 20%. A method for producing a biaxially oriented polyamide film, characterized by performing the following relaxation treatment. 6. A biaxially oriented polyamide film obtained by the production method according to any one of claims 1, 2, 3, 4, and 5. 7. A laminated film, comprising: a biaxially oriented polyamide film according to claim 6; and an inorganic vapor-deposited layer, and then a heat-sealing layer, laminated on at least one surface of the laminated film. 8. A laminated film comprising an anchor coat layer laminated between the biaxially oriented polyamide film according to claim 7 and an inorganic vapor-deposited layer. 9. A laminated film, wherein the inorganic vapor-deposited layer according to claim 6 or 7 is a thin film layer of silicon oxide, aluminum oxide or a mixture of silicon oxide and aluminum oxide.