JP2002029015A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically provide a laminated biaxially oriented polyamide film excellent not only in gas barrier properties and adhesiveness but also in transparency at an initial stage and even after boiling treatment in such a case that the laminated film is provided with a sealant layer to be used as a packaging bag. SOLUTION: In the laminated biaxially oriented polyamide film wherein an inorganic vapor deposition layer and a sealant layer are successively provided on the single surface of at least the A-layer of a biaxially oriented polyamaide film comprising layered constitution of A/B, A/B/A or A/B/C and characterized by that the density of projections with a height of 0.27 μm or more is <200/mm2 on the surface of the A-layer of the polyamide film over the total width of the polyamide film, the maximum dimensional change ratio of the biaxially oriented polyamide film during the immersion in hot water at 95 deg.C is 3.0% or less and the maximum dimensional change ratio difference of the polyamide film is 2.0% or less and the average dimensional change ratio after taken out of hot water is 4.0% or less and the maximum dimensional change ratio difference is 2.0% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in gas barrier properties and moisture proof properties, which are important properties in packaging films for fresh foods, processed foods, pharmaceuticals, medical equipment, electronic parts and the like.
The present invention relates to a laminated biaxially oriented polyamide film having excellent transparency and handleability.

[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, etc., it is important to suppress the oxidation and deterioration of proteins and fats and oils, and to maintain the taste and freshness. It is desired to block the permeation of air by using a. 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, butter, dairy products such as cheese, miso, tea, coffee, ham and sausage, instant food, castella, biscuits and other confectionery packaging films have the gas barrier properties and moisture barrier properties. Is a very important characteristic. 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.

[0005] Films having excellent gas barrier properties include:
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.

[0006] As a form actually used, a laminate of a polyamide film is provided by providing a sealant layer by a dry lamination method or a sealant layer by an extrusion lamination method on a printed layer and further provided with an adhesive. After the bag is prepared using the laminate and filled with the contents, the opening is heat-sealed, for example, a seasoning such as miso or soy sauce, a water-containing food such as a soup or a retort food, or a medicine is packaged. Offering to the general consumer.

The following problems have been pointed out in the conventional gas barrier films as described above. 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 base film on which silicon oxide, aluminum oxide, and the like are deposited, a polyester film (PET) having good dimensional stability has been used.
As a configuration, a laminated structure such as PET / deposited layer / adhesive layer / PET / adhesive layer / unstretched polypropylene (CPP) is generally used. However, a film having such a laminated structure has a drop impact. Insufficient strength is a problem.

On the other hand, PET / deposited 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.

[0010] Therefore, a nylon-laminated film 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 substrate 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 property, a laminated film (JP-B-7-1264) using stretched nylon having a reduced shrinkage in advance by heat treatment as a vapor 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 enters between the nylon film and the vapor deposition layer, the adhesive strength between the layers is remarkably reduced, and when the nylon film 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,
SiOx system with good gas barrier properties (x = 1.3-1.
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.

Further, as a gas barrier layer having boiling resistance and retort _resistance, although some of which have been proposed in JP-A-2-194944 as an example of Al ₂ O 3 · SiO _{2 system,} Al 2 _{O 3} And a layer of SiO ₂ , the formation of the gas barrier layer is complicated, and a large-scale apparatus is required. In addition, films using these inorganic thin films as gas barrier layers are still inadequate from the viewpoint of achieving both gas barrier properties and flex resistance. That is, in order to provide excellent boiling resistance and retort resistance, a certain degree or more (for example, 2,000Å) is required.
(More than about) is required, but if the film thickness is increased, there is a problem that the bending resistance is deteriorated and it cannot withstand a drop impact, and it has a sufficient gas barrier property and moisture proof property, and has boiling resistance. No gas barrier film has been proposed so far, which has good retort resistance and excellent bending resistance and can sufficiently withstand a drop impact.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has an object to provide a gas barrier property and an adhesive property even at the initial stage and after the boil treatment when a sealant layer is provided and used as a packaging bag. Another object of the present invention is to economically provide a laminated biaxially oriented polyamide film having excellent transparency and excellent transparency and bending fatigue resistance.

[0017]

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.

1. A / B, A / B / A, or A / B
A of biaxially oriented polyamide film having a layer structure of / C
The protrusion density of protrusions having a height of 0.27 μm or more on the layer surface is 2
Less than 00 / mm ² , wherein the biaxially oriented polyamide film is a laminated film provided with an inorganic vapor-deposited layer and then a sealant layer on at least one surface of layer A, and the biaxially oriented polyamide film is immersed in hot water at 95 ° C. Has an average dimensional change rate of 3.0% or less and a maximum dimensional change rate difference of 2.0% or less, and has an average dimensional change rate of 4.0% or less and a maximum dimensional change after being taken out from the hot water. 2.0% difference
A laminated biaxially oriented polyamide film characterized by the following.

2. The polyamide resin composition used for the A layer is a composition comprising X and Y shown below, or X
The polyamide resin composition used for the layer B is composed of a composition composed of a single component, a composition composed of Y alone, a composition composed of Y and X, a composition composed of Y and Z, or X, Y,
3. The laminated film according to the above item 2, which is composed of any one of the compositions consisting of X and / or Y, and wherein the polyamide resin composition used for the C layer is composed 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) (Y): Aliphatic polyamide-based resin (Z): Flex fatigue resistance improving agent comprising a mixture and / or a copolymer of (A) and containing the aromatic polyamide resin component (a) in an amount of 10 mol% or more.

3. The polyamide resin composition used for the A layer, or the A layer and the C layer, is obtained by mixing 50 to 100 parts by weight of the X and 50 to 0 parts by weight of the Y, and is used for the B layer. Is 0 to 10
Parts by weight, the Y is 80-100 parts by weight, and the Z is 0-1.
3. The laminated film according to the above 2, which is obtained by blending 0 parts by weight.

4. The laminated film according to any one of claims 1 to 3, wherein an anchor coat layer is laminated between the biaxially oriented polyamide film and the inorganic vapor-deposited layer.

5. The inorganic deposition layer is made of silicon oxide and / or
5. The laminated film according to any one of the above 1 to 4, wherein the laminated film is a mixture thin film layer of aluminum oxide.

6. Sequential biaxial stretching in which the substantially unoriented polyamide sheet having the layer structure of A / B, A / B / A, or A / B / C is stretched in the machine direction and then stretched three times or more in the transverse direction. In the method for producing a biaxially oriented polyamide film according to the method, the above-mentioned longitudinal stretching is defined as a first-stage stretching, and a glass transition temperature (Tg) + 10 ° C. or more and a low-temperature crystallization temperature (T
c) After stretching 1.1 to 3.0 times at a temperature of + 20 ° C or less, without cooling to a temperature of Tg or less, the second step stretching is continued at a temperature of Tg + 10 ° C or more and Tc + 20 ° C or less, The method for producing a biaxially oriented polyamide film according to any one of claims 1 to 5, wherein the film is stretched so that the stretching ratio becomes 3.1 to 4.0 times.

[0024]

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

In the present invention, the biaxially oriented polyamide film constituting the base layer has a height of 0.27 μm on the surface of the layer A.
The projection density of the above projections is less than 200 / mm ² ,
The average dimensional change during immersion in hot water at 95 ° C. is 3.0% or less, the maximum dimensional change difference is 2.0% or less, and the average dimensional change after removal from the hot water is 4.0. % And the maximum dimensional change rate difference must be 2.0% or less.

That is, in the biaxially oriented polyamide film, when the protrusion density of the protrusions having a height of 0.27 μm or more on the surface of the layer A is increased to 200 / mm ² or more, the protrusions during the boiling treatment or the retort treatment Due to the generated deformation stress, it causes the inorganic vapor deposition layer constituting the gas barrier layer of the laminated film to be broken or peeled off, and after boiling treatment, or after retort treatment, it is not possible to maintain excellent gas barrier properties. Not preferred.

The protrusion density of protrusions having a height of 0.27 μm or more on the surface of the layer A of the biaxially oriented polyamide film is 18
It is preferably 0 / mm ² or less, particularly preferably 150 / mm ² or less.

If the average dimensional change of the biaxially oriented polyamide film during immersion in hot water at 95 ° C. exceeds 3.0% and / or the maximum dimensional change exceeds 2.0%, boiling occurs. During the treatment, or during the retort treatment, causing a deformation stress in the inorganic vapor deposition layer constituting the gas barrier layer of the laminated biaxially oriented polyamide film, causing the inorganic vapor deposition layer to break or peel off, after boiling treatment, or After retort treatment, excellent gas barrier properties cannot be maintained, which is not preferable.

95 ° C. of the biaxially oriented polyamide film
The average dimensional change during immersion in hot water is preferably 2.7% or less, particularly preferably 2.3% or less. Further, the maximum dimensional change rate difference during immersion in 95 ° C. hot water is preferably 1.8% or less,
Particularly preferred is 1.5% or less.

Further, when the biaxially oriented polyamide film is immersed in hot water at 95 ° C. and taken out from the hot water, the average dimensional change exceeds 4.0%, and / or the maximum dimensional change difference is 2%. If it exceeds 0.0%, after boiling treatment, or
After the retort treatment, a deformation stress is generated in the inorganic vapor-deposited layer constituting the gas barrier layer of the laminated biaxially oriented polyamide film, causing destruction or peeling of the inorganic vapor-deposited layer, after the boiling treatment, or after the retort treatment, It is not preferable because excellent gas barrier properties cannot be maintained.

95 ° C. of the biaxially oriented polyamide film
The average dimensional change after taking out from the hot water after immersion in the hot water is preferably 3.5% or less, particularly preferably 3.0%.
It is as follows. Further, the maximum dimensional change rate difference after taking out from the hot water after immersion in hot water at 95 ° C. is preferably 1.8% or less, particularly preferably 1.5% or less.

That is, in the biaxially oriented polyamide film, the projection density of the projections having a height of 0.27 μm or more on the surface of the layer A is less than 200 / mm ² , and the average dimensional change rate during immersion in hot water at 95 ° C. Is 3.0% or less and the maximum dimensional change rate difference is 2.0% or less, and the average dimensional change rate after taking out from the hot water is 4.0% or less and the maximum dimensional change rate difference is 2. When the content is set to 0% or less, it functions as a support layer of the inorganic vapor deposition layer constituting the gas barrier layer, and particularly, excellent gas barrier properties can be maintained even after boiling treatment or retort treatment.

The following production method is suitable for producing the biaxially oriented polyamide film in which the projection density of the projections having a height of 0.27 μm or more on the surface of the layer A is less than 200 / mm ^2. .

A of the biaxially oriented polyamide film of the present invention
The layer has an average particle diameter of 0.5 to 5 μm, more preferably 0.5 to 3 μm, and contains 0 to 0.5% by weight of an inorganic lubricant such as silica, kaolin, or zeolite; And a fine particle for forming surface protrusions such as a high molecular weight organic lubricant such as polystyrene. Those having an average particle diameter of more than 5 μm are not preferred because the height of the projections on the film surface is high and the roughness is large, so that excellent gas barrier properties cannot be maintained. On the other hand, when the amount of the fine particles for forming surface projections exceeds 0.5% by weight, the height of the projections on the film surface becomes high and the roughness becomes large, so that it is not possible to maintain excellent gas barrier properties.

95 ° C. of the biaxially oriented polyamide film
The average dimensional change rate during immersion in hot water is 3.0% or less and the maximum dimensional change rate difference is 2.0% or less, and the average dimensional change rate after taking out from the hot water is 4.0% or less. In order to produce a laminated biaxially oriented polyamide film having a maximum dimensional change rate difference of 2.0% or less, the following production method is suitable.

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 the following composition composed of X and Y, or the composition composed 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) composed of terephthalic acid and aliphatic diamine or adipic acid and meta-xylylenediamine and an aliphatic polyamide resin or an aromatic polyamide resin composed of isophthalic acid and 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.

As the aliphatic polyamide used in the present invention, nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 612, nylon 46, a copolymer thereof, a blend thereof and the like can be mentioned. 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. And an ethylene / acrylate copolymer.

The polyamide film of the present invention has A /
Biaxial orientation comprising stretching a substantially unoriented polyamide sheet having a layer configuration of B, A / B / A, or A / B / C in two longitudinal steps, followed by transverse stretching, and heat setting. Polyamide films are preferred.

That is, when the substantially unoriented polyamide sheet is longitudinally stretched, the first-stage stretching is performed.
g and then the second stage of stretching is carried out without cooling to not more than 3.0 g, and then the film is horizontally stretched at a ratio of 3.0 times or more and 5.0 times or less, preferably 3.5 times or more and 4.2 times or less. And a biaxially oriented polyamide film obtained by heat setting. Known longitudinal stretching methods such as hot roll stretching and infrared radiation stretching may be used for the longitudinal stretching.

Next, a method for suitably producing the laminated biaxially oriented polyamide film of the present invention will be described in detail. First, the A / B, the A / B / A, or the A / B /
In forming a substantially unoriented polyamide sheet having a layer structure of C, the polymers constituting each layer are melted using a separate extruder, co-extruded, cast on a rotary drum from a die, and quenched and solidified. To obtain a polyamide sheet, a method of laminating the polymer constituting each layer by lamination,
And a method combining them. This polyamide sheet is in a substantially unoriented state.

This unstretched polyamide sheet is first treated with Tg
At a temperature of + 10 ° C. or more and Tc + 20 ° C. or less, 1.1 to
The first stage stretching is performed 3.0 times. When the ratio is 1.1 or less, the stretching effect is not exhibited. When the ratio exceeds 3.0, oriented crystallization proceeds, and the stretching stress in the second-stage stretching described later increases, causing breakage, or breaking in lateral stretching. Is not preferred because it leads to More preferably, it is 1.5 to 2.5 times. If the stretching temperature is lower than Tg + 10 ° C., necking is likely to occur and thickness unevenness tends to increase, and if it exceeds Tc + 20 ° C., thermal crystallization remarkably progresses, and it is easy to break in transverse stretching, which is not preferable. More preferably, it is Tg + 20 to Tc + 10 ° C.

After the first-stage stretching, the second-stage stretching is continued. One of the features of the present invention is how to adjust the sheet temperature during the second-stage stretching. In other words, the purpose is to keep the temperature warm by heating instead of forcibly cooling, and to also use the preheating for the second-stage stretching or the heating for the stretching. When cooling is performed forcibly and then reheated for the second-stage stretching, thermal crystallization remarkably progresses, the transverse stretching stress increases, and breakage occurs frequently, which is not preferable. Thermal crystallization proceeds even in the heating and holding section where the temperature is not cooled below Tg, but is much slower than the above-mentioned forced cooling and reheating, and does not pose a practical problem.

Next, this sheet is subjected to a total longitudinal stretching ratio of:
It is stretched in the second step so as to be 3.1 to 4.0 times. 3.1
When the ratio is less than 2 times, the transverse stretching stress is reduced and the fracture is reduced, but the strength in the longitudinal direction is reduced, and when the ratio is more than 4.0 times, the transverse stretching stress is remarkably increased and the frequent breaking is not preferred. The total longitudinal stretching ratio is preferably from 3.3 to 3.7 times.

The second-stage longitudinal stretching temperature is from Tg + 10 ° C.
Tc + 20 ° C. If the temperature is lower than Tg + 10 ° C., the transverse stretching stress increases remarkably, and rupture frequently occurs.
If the temperature exceeds 0 ° C., the thickness unevenness increases, thermal crystallization remarkably progresses, the transverse stretching stress increases, and breakage occurs frequently, which is not preferable. More preferably, it is Tg + 20 ° C. to Tc + 10 ° C.

The uniaxially oriented polyamide film thus obtained is horizontally stretched 3.0 to 5.0 times at 100 ° C. to a temperature lower than the melting point using a stenter, and then heat-fixed and wound up. Preferably, the transverse stretching temperature is 100 to 180.
° C, and the transverse stretching ratio is 3.5 to 4.2 times. If the transverse stretching temperature is too low, the transverse stretchability deteriorates (breakage occurs), and if it is too high, the thickness unevenness worsens. If the stretching ratio in the transverse stretching is not 3 times or more, the strength in the transverse direction is reduced.

As described above, the longitudinal stretching of the substantially unoriented polyamide sheet having the layer structure of A / B, A / B / A, or A / B / C is divided into two stages. After stretching,
Without being cooled to Tg or less, the second-stage stretching is continuously performed, and then transverse stretching and heat setting are performed, so that the average dimensional change rate of the biaxially oriented polyamide film during immersion in hot water at 95 ° C. is 3.0% or less. And the maximum dimensional change rate difference is 2.0% or less, and the average dimensional change rate after taking out from the hot water is 4.0% or less and the maximum dimensional change rate difference is 2.0%.
The following biaxially oriented polyamide film, which is a base film of a laminated biaxially oriented polyamide film, can be obtained as follows.

The reason for this is that by performing longitudinal stretching in two stages, the sheet surface is subjected to heat history and thermal crystallization is appropriately promoted, and the surface crystallization of the obtained biaxially oriented polyamide film is promoted. It is considered that the hygroscopicity of the axially oriented polyamide film is reduced, and the dimensional change during immersion in hot water and after release of the hot water is reduced. At the same time, the longitudinal stretching is
Not only the effect of reducing the stretching stress by dividing into stages, but also the crystallization promoting effect by the hydrogen bond peculiar to polyamide generated at the time of reheating from forced cooling is prevented by heating and maintaining the temperature between the first stretching and the second stretching. Further, since the sheet orientation relaxing action is drawn out after the first-stage stretching, and the structure of the uniaxially oriented film before the transverse stretching is made gentle, the formation of the transverse orientation which appears during the transverse stretching becomes easy, and the transverse stretching stress is further increased. It is considered that the drawability is improved by the reduction. As a result, a biaxially oriented polyamide film with less operation trouble can be economically provided.

Next, examples of the inorganic vapor deposition layer constituting the gas barrier layer include silicon oxide, aluminum oxide, magnesium oxide, and mixtures thereof. The term “silicon oxide” used herein includes a mixture of various silicon oxides such as SiO and SiO ₂ , and the term “aluminum oxide” includes a mixture of various aluminum oxides such as AlO and Al ₂ O ₃ . The amount of oxygen bonded differs depending on the production conditions.

In particular, 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 to 45% by weight is preferable.

If the content of aluminum oxide in the silicon oxide / aluminum oxide-based vapor-deposited film is less than 5% by weight, a lattice defect occurs in the vapor-deposited film, and a sufficient gas barrier property cannot be obtained. On the other hand, if the aluminum oxide content in the silicon oxide / aluminum oxide-based deposited film exceeds 45% by weight, the flexibility of the film is reduced, and the film is broken (cracked or peeled) due to dimensional change during hot water treatment. This causes a problem that the barrier property is deteriorated, which is not suitable for the purpose of the present invention.

A more preferred ratio of aluminum oxide is
It is 10 to 35% by weight, more preferably 15 to 25% by weight. The silicon oxide / aluminum oxide-based deposited film may further contain a trace 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 °. 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 vapor 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 adopted, 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 may be resistance heating, induction heating, electron beam heating, or the like, and may include oxygen, nitrogen,
It is also possible to introduce reactive gas such as introduction of hydrogen, argon, carbon dioxide, water vapor, or the like, or to use reactive vapor deposition using means such as ozone addition or ion assist. Further, the film forming 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, and the like can be similarly changed when a sputtering method or a CVD method is adopted.

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

The gas barrier property of the laminated film having an inorganic vapor-deposited layer provided on at least one surface of the biaxially oriented polyamide film of the base layer according to the present invention and then providing a sealant layer includes the biaxially oriented polyamide film serving as the base layer and the gas barrier layer. The adhesion strength with the layer is greatly related, and the gas adhesion is improved 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 set to 100 g / 15 m.
m. A more preferable adhesion strength is 150 g / 15 mm or more, further preferably 200 g / 15 mm or more, and further preferably 250 g / 15 mm or more.
It is 15 mm or more. When the adhesion strength is less than 100 g / 15 mm, the gas barrier property tends to be deteriorated by the boiling treatment. It is considered that the reason for this is 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 rough surface treatment on the surface of a biaxially oriented polyamide film serving as a base layer of an inorganic vapor deposition layer. There is a method such as applying a surface treatment or forming an anchor coat layer for improving adhesion on a polyamide resin film,
Of course, it 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, it is preferable to use an aqueous polyester resin from the viewpoint of cost and hygiene in order to improve the adhesion strength between the base layer and the inorganic vapor deposition layer by forming the anchor coat layer. . 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 0.1.
01 to 10 μm, more preferably 0.02 to 5 μm. When the thickness is less than 0.02 μm, the effect of improving the adhesion strength tends to be hardly exerted. The effect of improving the adhesion described above is not exhibited, and this is economically disadvantageous.

A heat seal layer made of a polyolefin resin is formed on the surface of the inorganic vapor-deposited layer in order to impart thermal adhesion, and the heat seal layer also functions as a protective layer of the inorganic vapor-deposited layer. In order to effectively perform its function, it is extremely effective to increase the adhesive force between the inorganic vapor-deposited layer and the heat seal layer. It is extremely effective to provide an adhesive layer on the substrate.

The polyolefin resin constituting the heat seal layer does not necessarily have to be a single layer, and 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.

Various additives such as plasticizers, heat stabilizers, ultraviolet absorbers, antioxidants, coloring agents, fillers, antistatic agents, etc. may be added to the polyolefin resin constituting the heat seal layer, if necessary. 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 seal layer on the inorganic vapor-deposited layer by a dry lamination method or a wet lamination method using an adhesive, and further by a melt extrusion lamination method or a co-extrusion lamination method. You.

The thus obtained laminated film or sheet of the present invention makes use of its excellent gas barrier properties, gas barrier durability by boiling treatment and retort treatment, and secondary processing characteristics, and is used as a packaging material for miso, pickles, prepared foods, baby foods, Tsukudani, konjac, chikuwa, kamaboko, fishery 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, buns, castella, It can be effectively used for packaging of cheese, butter, rice cake, soup, sauce, ramen, wasabi, toothpaste, etc., and furthermore, pet food, pesticide, fertilizer, infusion pack, semiconductor or precision material packaging, etc. Medical,
It can also be used effectively for packaging of industrial materials such as electronics, chemicals and machinery. 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.

[0071]

Next, the present invention will be described in detail with reference to examples.

The present invention is not limited by the following examples, and it is of course possible to carry out the present invention with appropriate modifications within a range that can be adapted to the spirit of the preceding and the following.
All of them are included in the technical scope of the present invention. Various performance tests adopted in the following examples were performed by the following methods.

(1) Projection density on the film surface: A single ring (projection height: 0) observed by evaporating alumina under vacuum on the film surface and attaching a filter of 0.54 μm wavelength to a two-beam interference microscope. (Equivalent to .27 μm) was measured over 1.3 mm ^2, and the number (density) per unit area was determined.

(2) 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).

(3) Adhesion strength: The laminated product was peeled 180 ° 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) Glass transition temperature (Tg) and low-temperature crystallization temperature (Tc): A non-oriented polyamide sheet is frozen in liquid nitrogen, thawed under reduced pressure, and then heated at a rate of 10 ° C./min using 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.

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

(6) Film forming condition: The film was successively biaxially stretched under the same conditions for 2 hours, and the number of breaks was examined.

(7) Dimensional change rate A strip having a length of 100 mm and a width of 10 mm prepared at a pitch of 10 ° with respect to all directions of the film was placed at 23 ° C. and 65% R
After leaving for 2 hours under H environment, 25m from both ends in the length direction
Mark lines are drawn at the position of m (the portion fixed by the chuck), and the distance between the mark lines is defined as the length before processing (A: mm). Then, using a heat shrinkage stress tester (manufactured by A & D Co., Ltd.) equipped with a differential transformer type displacement measuring device, the strip sample was fixed with a chuck, and an initial load of 1
0 g of the sample was applied to the sample, and the interval between marked lines when immersed in hot water of 95 ° C. for 30 minutes was measured, and the length after the treatment during immersion in hot water (B: mm) was defined. Thereafter, a strip sample was taken out of the hot water to remove water adhering to the surface.
After leaving for 2 hours in an environment of 65 ° C. and 65% RH, the interval between marked lines was measured, and the length after the treatment after removal from hot water (C: mm)
And The dimensional change rate can be obtained by the following equations (1) and (2). The average dimensional change rate indicates an average value of the dimensional change rates measured in all directions of the film at a pitch of 10 °. The maximum dimensional change rate difference indicates the difference between the maximum value and the minimum value of each dimensional change rate measured as described above. Dimensional change rate during hot water immersion (%) = │AB│ / A × 100 (1) Dimensional change rate (%) after taking out from hot water = │AC│ / A × 100 ... (2)

(Example 1) As the A layer, fine particles for forming surface protrusions (average particle diameter 2.0 μm, pore volume 1.6 ml /
g of silica fine particles) to a concentration of 0.15% by weight using a nylon 6 master batch, and 28 parts by weight of nylon 6 and a nylon 6T / nylon 6 copolymer (copolymerization ratio: 62/3).
8) 72 parts by weight of the mixture, as layer B, using the nylon 6 masterbatch of the fine particles for forming surface protrusions, 0.4
0% by weight, 100 parts by weight of nylon 6 and C layer were adjusted to 0.60% by weight using the nylon 6 masterbatch of the fine particles for forming surface protrusions, and 100 parts by weight of nylon 6 were A / B / C thickness ratio (%) is 15
It is melt-extruded while being laminated so as to have a configuration of / 70/15, applied with a high DC voltage, electrostatically adhered onto a rotating drum at 20 ° C., cooled and solidified to form an unoriented polyamide sheet having a thickness of 200 μm. Obtained. The Tg of this sheet is 5
0 ° C. and Tc were 78 ° C.

This sheet was subjected to the first-stage longitudinal stretching at a stretching temperature of 80 ° C. 1.6 times, and then kept at 75 ° C. while stretching at a stretching temperature of 82 ° C.
The second-stage longitudinal stretching was carried out so that the total stretching ratio became 3.4 times at ℃, and the sheet was continuously guided to a stenter, stretched four times at 140 ° C, heat-set at 210 ° C, and %, And then cooled, and both edges were cut off to obtain a biaxially oriented polyamide film having a thickness of 16 μm. At this time, no break occurred at all even if film formation was continued for 2 hours under the same conditions. Further, after the longitudinal stretching, the water-dispersible acrylic graft polyester resin was added in a thickness of about 0.
It was coated so as to have a thickness of 1 μm.

This film was sent to a vacuum deposition apparatus, and the inside of the chamber was maintained at a pressure of 1 × 10 ⁻⁵ Torr,
₂ : 70% by weight and Al ₂ O 3: 30% by weight The mixed oxide was evaporated by electron beam heating of 15 kW to a thickness of 180 °.
Was deposited on the coating surface to form an inorganic vapor-deposited layer. Next, unstretched polyethylene (thickness:
50 μm) with an adhesive (“A310 / A1 manufactured by Takeda Pharmaceutical Co., Ltd.)
0 ", application amount 2 g / m ² ), and aged at 45 ° C. for 4 days to obtain a laminated film.

The following (5) to (5)
The evaluation of (8) was carried out, and the biaxially oriented polyamide film of the base layer was subjected to the following (1) to (4) in addition to the film forming conditions (the number of breaks when biaxially stretched sequentially under the same conditions for 2 hours). An evaluation was performed. (1) Oxygen permeability of untreated film (ml / m ² · day · MP
a) (2) After immersion in 95 ° C hot water for 30 minutes, oxygen permeability of the film after standing for 1 hour (ml / m ² · day · MPa) (3) After immersion in 95 ° C hot water for 30 minutes Adhesion force (mN) when water is dropped on the peeling interface of the film after leaving for 1 hour
/ 4mm) (4) Projection density on film surface (pcs / mm ² ) (5) Average dimensional change rate during hot water immersion (%) (6) Maximum dimensional change rate difference during hot water immersion (%) (7) ) Average dimensional change rate after removal from hot water (%) (8) Maximum dimensional change rate difference after removal from hot water (%) The above results are shown in Table 1.

(Example 2) As the layer A, the nylon 6 masterbatch of the fine particles for forming surface protrusions was used to obtain
A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1 except that 2% by weight was added. During the production of the biaxially oriented polyamide as the base layer, no break occurred at all even if the film formation was continued for 2 hours under the same conditions.

Example 3 A layer A was prepared by using a mixture of 10 parts by weight of nylon 6 and 90 parts by weight of a nylon 6T / nylon 6 copolymer (copolymerization ratio: 62/38).
A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1. At this time, no break occurred at all even if film formation was continued for 2 hours under the same conditions.

(Example 4) As a C layer, a mixture of 22 parts by weight of nylon 6 and 78 parts by weight of MXD-6 was used.
A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1 except that the thickness ratio (%) of / B / C was set to 15/70/15. At this time, no break occurred at all even if film formation was continued for 2 hours under the same conditions.

(Comparative Example 1) A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1 except that the second-stage longitudinal stretching was performed so that the total stretching ratio was 2.6 times. At this time, no break occurred at all even if film formation was continued for 2 hours under the same conditions.

(Comparative Example 2) A layer A was prepared by using a mixture of 70 parts by weight of nylon 6 and 30 parts by weight of a nylon 6T / nylon 6 copolymer (copolymerization ratio: 62/38).
A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1. At this time, no break occurred at all even if film formation was continued for 2 hours under the same conditions.

(Comparative Example 3) As the layer A, a nylon 6 masterbatch of the fine particles for forming surface protrusions was used, and 0.7
A laminated biaxially oriented polyamide film was obtained in the same manner as in Example 1 except that 0% by weight was added. During the production of the biaxially oriented polyamide as the base layer, no break occurred at all even if the film formation was continued for 2 hours under the same conditions.

(Comparative Example 4) After the first-stage longitudinal stretching, the temperature was 40 ° C.
A biaxially oriented polyamide film was produced in the same manner as in Example 1 except that the film was rapidly cooled and reheated for the second-stage longitudinal stretching.

[0091]

[Table 1]

[0092]

According to the present invention, a laminated biaxial not only having excellent gas barrier properties without breakage but also having excellent gas barrier properties even after boil treatment and having excellent adhesiveness. It is effective for economically producing an oriented polyamide film.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 22 B29K 105: 22 B29L 9:00 B29L 9:00 (72) Inventor Katsuya Ito Otsu City, Shiga Prefecture 2-1-1 Katata F-Term in Toyobo Co., Ltd. Research Laboratory (reference) 4F100 AA01C AA19C AA20C AK46A AK46B AK47A AK48A AL01A AL05A BA04 BA05 BA07 BA10B BA10D BA13 CA30A CB00E DD07A EG003 EB003 GB17 EJ003 JD04 JK04A JL04A JL05 JL11E JL12D JN01 YY00 YY00A 4F210 AA29 AC03 AD03 AD05 AD20 AD34 AG03 QA02 QA03 QC06 QD13 QG01 QG11 QG15 QG18 4J002 BB073 BB153 BG003 CF173 CL01207 CL032 CL032

Claims (6)

[Claims] 1. A / B, A / B / A, or A / B / C
The protrusion density of protrusions having a height of 0.27 μm or more on the surface of the layer A of the biaxially oriented polyamide film having a layer structure of
/ Mm ² , and a laminated film provided with an inorganic vapor-deposited layer and then a sealant layer on at least one side of the A layer of the biaxially oriented polyamide film, wherein the biaxially oriented polyamide film is immersed in hot water at 95 ° C. The average dimensional change rate is 3.0% or less and the maximum dimensional change rate difference is 2.0% or less, and the average dimensional change rate after taking out from the hot water is 4.0% or less and the maximum dimensional change rate. A laminated film having a difference of 2.0% or less. 2. The polyamide resin composition used for the layer A is composed of a composition composed of X and Y shown below or a composition composed of X alone, and the polyamide resin composition used for the layer B is composed of Y alone. Consisting of a composition consisting of Y, X, a composition consisting of Y and Z, or a composition consisting of X, Y, and Z;
The laminated film according to claim 1, wherein the polyamide resin composition used for the layer comprises a composition comprising 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) (Y): Aliphatic polyamide-based resin (Z): Flex fatigue resistance improving agent comprising a mixture and / or a copolymer of (A) and containing the aromatic polyamide resin component (a) in an amount of 10 mol% or more. 3. The polyamide resin composition used for the A layer or the A layer and the C layer is obtained by mixing 50 to 100 parts by weight of the X and 50 to 0 parts by weight of the Y, and is used for the B layer. The polyamide resin composition obtained is such that X is 0 to 10 parts by weight, Y is 80 to 100 parts by weight, and Z is 0 to 10 parts by weight.
The laminated film according to claim 1, which is obtained by blending parts by weight. 4. The laminated film according to claim 1, wherein an anchor coat layer is laminated between the biaxially oriented polyamide film and the inorganic vapor deposition layer. 5. The laminated film according to claim 1, wherein the inorganic vapor-deposited layer is a mixture thin film layer of silicon oxide and / or aluminum oxide. 6. The A / B, the A / B / A, or the A / B
In the method for producing a biaxially oriented polyamide film by a sequential biaxial stretching method in which a substantially unoriented polyamide sheet having a layer structure of B / C is stretched in the longitudinal direction and then stretched three times or more in the transverse direction, As the first-stage stretching, the glass transition temperature (Tg) + 10 ° C. or more, the low-temperature crystallization temperature (Tc) +
After stretching 1.1 to 3.0 times at a temperature of 20 ° C. or less,
It is characterized in that it is stretched so that the total longitudinal stretching ratio is 3.1 to 4.0 times at a temperature of Tg + 10 ° C. or more and Tc + 20 ° C. or less as a second stage stretching without cooling to Tg or less. The method for producing a biaxially oriented polyamide film according to claim 1.