JP2017177343A - Laminate film and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film that serves as a moist heat-resistant gas barrier film having good gas barrier properties and high transparency by grasping an accurate composition of an aluminum oxide vapor deposition film.SOLUTION: The laminate film has an aluminum oxide film laminated on at least one surface of a polymer film. In the laminate film, when respective fractions of aluminum atomic numbers derived from metal aluminum, aluminum oxide and aluminum hydroxide in the aluminum oxide film are represented as a, b and c, respectively, (a+b+c=1), a is in the range of 0 to 0.07 and c is in the range of 0 to 0.17; and the aluminum oxide film has a density of 2.5 g/cmor more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminated film and a method for producing the same. More specifically, the present invention relates to a laminated film for a moisture and heat resistant gas barrier film, which has high transparency and good visibility, has high gas barrier performance, and can suppress deterioration and deterioration of contents such as foods, and a method for producing the same.

  A gas barrier film in which a metal such as aluminum, aluminum oxide or silicon oxide or a metal oxide thin film is formed on a base film by a forming means such as a vacuum deposition method is used as a packaging material. As the base film, a polyester film typified by a biaxially stretched polyethylene terephthalate film is suitably used because it is excellent in heat resistance, dimensional stability, thickness uniformity, and the like.

  The food packaging material in which the gas barrier film is laminated is suitably used as a packaging material having excellent gas barrier properties, water resistance and moisture resistance, and excellent boil resistance, retort resistance and environmental compatibility. Among them, those formed with a metal oxide thin film are widely used because the contents can be visually recognized due to transparency and convenience due to suitability for a microwave oven.

  A gas barrier film using aluminum oxide as a deposited film can obtain a high light transmittance. However, when the degree of oxidation of aluminum oxide is increased, there is a problem that the gas barrier property is lowered. Conversely, if the degree of oxidation of aluminum is kept low, the gas barrier property is improved, but the permeability is lowered.Therefore, the composition is less oxygen than the fully oxidized state of aluminum oxide, and a compromise between gas barrier property and transmittance is achieved. A method of finding is proposed (see Patent Documents 1, 2, and 3). These methods were based on the premise that unreacted aluminum remains in the deposited film and causes light absorption, and thus the transmittance was slightly low.

  On the other hand, in order to obtain a better combination of transmittance and gas barrier properties, a method of changing the ratio of aluminum and oxygen in the film thickness direction has also been proposed (see Patent Document 4).

  In this way, the conventional aluminum oxide vapor deposition film tried to solve the problem of incompatibility between the transmittance and the gas barrier property by a method for finding the compromise, but any method can balance the permeability and the gas barrier property. There is a problem that the range of manufacturing conditions is small, and either the transmittance or the gas barrier property tends to be lowered due to the deviation of the conditions.

  In addition, a method has been proposed in which vapor deposition is completed in a state where the degree of oxidation is low and the transmittance is increased by leaving it in high humidity (see Patent Document 5). Also disclosed is a method for producing a transparent gas barrier film, characterized in that after an aluminum oxide thin film is provided, moisture is adsorbed on the aluminum oxide thin film, followed by heat treatment (see Prior Document 6). According to these methods, the transparency is improved, but a process for this purpose and a lead time until the gas barrier performance is developed are required, and the gas barrier performance is insufficient.

  In the process of development focusing on the oxidation state of aluminum oxide in this way, the element composition ratio O / Al of oxygen to aluminum in aluminum oxide can take from 0 to 1.7, exceeding 1.5. Examples have also been reported (Patent Document 7), and have also reached 1.7 to 2.3 (Patent Document 8) and 1.3 to 2.0 (Patent Document 9).

That is, the composition of the aluminum oxide vapor deposition film is often described as AlO _x based on the stoichiometric composition of aluminum oxide Al ₂ O ₃ , and x is 0 to 1.5 if the oxidation is incomplete. The portion less than 1.5 and less than 1.5 means oxygen deficiency due to insufficient oxidation of the deposited film, and the remaining metal aluminum component is considered to cause light absorption. On the other hand, no specific mode is shown for the chemical state of the portion exceeding 1.5, and it is recognized that this is due to the difference in sensitivity of each element by the measurement method.

  The appearance of the roll wound with the film on which the vapor-deposited film of the oxidation deficient aluminum oxide is formed is black or gray because the color tone of the vapor-deposited film is emphasized by the overlap of the films. If the thickness of the deposited film and the degree of oxidation are subtle in the width direction of the roll, strip-shaped unevenness appears on the roll, which is undesirable as an appearance of the intermediate product of the packaging material.

  Moreover, if it is white printing when used as a food packaging material, the color tone becomes dull and yellowish, which is a cause of reducing the attractiveness of the appearance of the product. As described above, the deterioration of the transmittance of one film is not large, but the demand for the appearance quality is increasing, and the gas barrier property by the aluminum oxide vapor deposition film which can stably express the high gas barrier property and transparency at the same time. The development of the film is awaited.

Japanese Patent Laid-Open No. 10-53861 JP-A-62-103359 JP-A-5-338072 JP-A-10-226021 JP-A-11-262969 JP 63-223163 A JP 2007-144845 A JP 2012-56311 A JP2015-186904A

  The present invention is intended to solve such problems of the prior art, and it is a laminate that provides an accurate composition of an aluminum oxide vapor-deposited film to provide a gas barrier film with good gas barrier properties and high transparency. The object is to provide a film.

  In order to solve the above problems, the present invention has the following configuration.

In the first invention, an aluminum oxide film is laminated on the surface of at least one side of the polymer film, and the fraction of the number of aluminum atoms caused by the metal aluminum, aluminum oxide, and aluminum hydroxide in the aluminum oxide film is respectively determined. When represented by a, b, c (a + b + c = 1), a is in the range of 0 to 0.07, c is in the range of 0 to 0.17, and the density of the aluminum oxide film is 2.5 g / It is a laminated film which is cm ³ or more.

  The second invention is characterized in that the film thickness of the aluminum oxide film is in the range of 5 to 100 nm.

A third invention is a method for producing a laminated film as described above, wherein a plasma activated vapor deposition method is used to generate a high density plasma in a space between an aluminum evaporation source and the polymer film, and an aluminum oxide film is formed. An aluminum oxide film is laminated on the surface of a polymer film while supplying an oxygen gas of 2d to 4d (cc / m ² ) per 1 m ^{2 of} vapor deposition area with respect to the thickness d (nm), and the production of the laminated film Is the method.

  A fourth invention is characterized in that, in the third invention, the method for generating high-density plasma is a hollow cathode plasma source.

  According to a fifth invention, in the third or fourth invention, the polymer film is subjected to a surface treatment using plasma or low energy ions, and aluminum oxide is laminated thereon.

  According to the present invention, an accurate composition of an aluminum oxide vapor deposition film can be grasped, and a gas barrier film having good gas barrier properties and high transparency is provided. The aluminum oxide film according to the present invention is dense, can obtain high transparency and gas barrier properties at the same time, and the color tone of the laminated film roll does not have gray unevenness.

It is a phase diagram which shows the relationship between the metal aluminum in the laminated | multilayer film of this invention, aluminum oxide, and aluminum hydroxide. It is an example of the manufacturing apparatus of the laminated | multilayer film of this invention.

In the laminated film of the present invention, an aluminum oxide film is laminated on the surface of at least one side of the polymer film, and the fraction of the number of aluminum atoms caused by metal aluminum, aluminum oxide and aluminum hydroxide in the aluminum oxide film is represented by a , B, c (a + b + c = 1), a is in the range of 0 to 0.07, c is in the range of 0 to 0.17, and the density of the aluminum oxide film is 2.5 g / It is a laminated film which is cm ³ or more.

  The polymer film in the present invention is not particularly limited as long as it is a film made of an organic polymer compound. For example, polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyamide, polycarbonate, polystyrene, polyvinyl A film made of various polymers such as alcohol, saponified ethylene vinyl acetate copolymer, polyacrylonitrile, polyacetal and the like can be used, and a polyester film made of polyester is preferable. Polyester of the polyester film is a general term for polymers having an ester bond with an acid and an alcohol, and is typically a condensation polymer of a dicarboxylic acid and a diol, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN). Are manufactured at low cost industrially. Among them, PET is excellent in moldability and physical property balance, and it is preferable to use a PET film biaxially stretched by a conventional method.

  In the laminated film of the present invention, an aluminum oxide film is laminated on the surface of at least one side of the polymer film. The aluminum oxide film is composed of not only aluminum atoms and oxygen atoms but also hydrogen atoms.

Conventionally, X-ray photoelectron spectroscopy or Auger electron spectroscopy has been used to measure the ratio of aluminum to oxygen, but HR-RBS / HR-HFS (High-- By using the Resolution Rutherford Back Scattering / High-Resolution Hydrogen Scattering) method, the composition ratio of hydrogen, oxygen, and aluminum C _Al , C _O , C _H (C _Al + C _O + C _H = 1), number of units Can be measured.

The aluminum oxide film is made of a mixture of metal aluminum, aluminum oxide, and aluminum hydroxide. In the past, incomplete oxidation atomic states such as AlO, Al ₂ O ₂ , and Al ₂ O ₃ have been proposed as the structure of aluminum oxide by vapor deposition (for example, Patent Document 6), and stoichiometric in terms of AlO _x. Although an oxidation state different from that of Al ₂ O ₃ has been suggested, such an incomplete oxidation atomic state cannot be taken for aluminum, and is described by a mixture of metal aluminum, aluminum oxide and aluminum hydroxide. It is appropriate to do.

When the fractions of the number of aluminum atoms resulting from metal aluminum, aluminum oxide, and aluminum hydroxide in the aluminum oxide film are expressed as a, b, and c (a + b + c = 1), the composition of the aluminum oxide film is aAl + bAlO _{1. 5} + cAl (OH) ₃

Since this equation can be transformed to (a + b + c) Al + (1.5b + 3c) O + 3cH, that is, Al + (1.5b + 3c) O + 3cH, the ratio of the number of oxygen atoms to the number of aluminum atoms (O / Al) in the above composition is 1.5b + 3c, the ratio of the number of hydrogen atoms to the number of aluminum atoms (H / Al) is 3c, and by obtaining C _Al , C 2 _{O 3} and C 3 _H by the above-mentioned HR-RBS / HR-HFS method, a, b, c Can be determined as follows.

c = C _H / 3C _{Al
b = (C O -C H)} /1.5C Al
a = 1- (b + c)
The factor that hinders the transparency of the deposited aluminum oxide film is that metal aluminum remains. In the above formula, a is an amount corresponding to metal aluminum. If this a is 0, all aluminum is in a reacted state, and light absorption due to metallic aluminum is eliminated. Since the proportion of metallic aluminum increases as a increases, in the present invention, a is 0.07 or less, which is an appropriate range with less light absorption. That is, in the present invention, a is in the range of 0 to 0.07. A range of 0 to 0.05 is more preferable for improving transparency. More preferably, it is in the range of 0 to 0.03.

  Furthermore, in the present invention, the fraction c of aluminum hydroxide is in the range of 0 to 0.17. The aluminum hydroxide portion in the aluminum oxide film has insufficient gas barrier performance as compared with the aluminum oxide portion, and in particular, is inferior in the moisture and heat resistance gas barrier performance, so it is important that the aluminum hydroxide portion is small. c is more preferably in the range of 0 to 0.10, and still more preferably in the range of 0 to 0.08.

1.5b + 3c corresponds to the ratio (O / Al) of the number of oxygen atoms and the number of aluminum atoms contained as aluminum oxide and aluminum hydroxide. This value has been shown so far in the prior art as the value of x for AlO _x .

As a conventional expression, let us consider a stoichiometric state of x = 1.5 when hydrogen is present but is not noticed and expressed as AlO _x . Hereinafter, description will be made with reference to the phase diagram shown in FIG. That is, FIG. 1 is a phase diagram showing a possible range of (a, b, c) on the assumption that a + b + c = 1, where the bottom left edge vertex is a = 1, that is, 100% metallic aluminum, and the top vertex b = 1. Indicates the state of AlO _1.5 100%, and the bottom right edge vertex c = 1 indicates Al (OH) ₃ 100%. Line 11 shows the state of x = 1.5b + 3c = 1.5, i.e. b + 2c = 1. b + 2c = 1 exists continuously from complete aluminum oxide AlO _1.5 to the midpoint on the base where b = 0 without aluminum oxide (the base indicated by 15). AlO _1.5 with b = 1 is perfect aluminum oxide, which is a desirable composition in the present invention. However, if c increases due to the increase in aluminum hydroxide while maintaining this x = 1.5 relationship, it does not shift to Al (OH) _1.5 , but 0.5 × Al + 0.5 × Al ( OH) ₃ (point shown in 12). For example, when c = 0.15, b = 0.7 and a = 0.15, which are outside the proper range in the present invention (points indicated by 13). That is, until now, even if x is determined, there are infinite combinations of (a, b, c), and the composition of the aluminum oxide film cannot be uniquely determined.

  The range in which a is 0 to 0.07 and c is 0 to 0.17 in the present invention is confirmed using FIG. The line 17 is a line indicating a = 0.07, and the right side is a range of 0 to 0.07 of a. The line 18 is a line indicating c = 0.17, and the left side is a range where c is 0 to 0.17. That is, the region indicated by the rhombus 19 is a range where a is 0 to 0.07 and c is 0 to 0.17.

  According to FIG. 1, b + 2c = 1, that is, the region to the right of the line 11 is b + 2c> 1 and O / Al> 1.5. The composition of x> 1.5 mentioned in the prior art documents 7 to 9 can be realized when c> 0 and the total amount of oxygen in the film is large due to the presence of hydroxyl groups. And the rate which aluminum reacted is not necessarily high, and there may be a state in which the transmittance of metal aluminum remaining is low.

  The value of O / Al is 1.7 to 2.3 in the prior document 8, and 1.3 to 2.0 in the prior document 9. O / Al (= 1.5b + 3c) in the present invention has a maximum value of 1.76 and a minimum value of 1 in the range of 0 ≦ a ≦ 0.07 and 0 ≦ c ≦ 0.17 in the present invention. .40, which is a relatively low value.

  As described above, the ratio of metal aluminum cannot be grasped only by the value of O / Al in the prior art, and it is insufficient as an index of an aluminum oxide vapor deposition film for obtaining high transmittance. The reason for this recognition is considered to be the measurement method as described above. Until now, the oxidation state of aluminum has been measured by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy. Since these methods do not detect hydrogen, hydroxyl groups caused by aluminum hydroxide are not recognized, and aluminum and The reason seems to be that only oxygen was evaluated as the composition of the deposited aluminum oxide film.

  The reason why the above aluminum hydroxide is produced is that when the partial pressure of water contained in the residual gas in the vacuum vapor deposition machine is high, aluminum and water react and are taken into the film. In order to prevent the influence, it is considered that it is not the main reason for generation because it is usually taken before evacuation until the vacuum is exhausted to a certain degree of vacuum and the residual gas is removed. Rather, it seems to be mainly due to the fact that the metal aluminum reacts with water in the atmosphere spontaneously after being taken out from the vacuum vapor deposition device in a state where the oxidation during vapor deposition is insufficient and metal aluminum remains. In Patent Documents 5 and 6, this process is actively used. It seems that some oxygen is taken in at the same time, but it is difficult to grasp the breakdown with the amount taken up at the time of vapor deposition.

  This post-deposition reaction does not complete the reaction of all metallic aluminum, and it is inevitable that metallic aluminum remains. Further, the lower the degree of oxidation during vapor deposition, the greater the amount of remaining metal aluminum, and accordingly the degree of hydroxylation after vapor deposition increases, resulting in a film with a large amount of both metal aluminum and aluminum hydroxide. Therefore, as described above, it is important that the proportion of aluminum hydroxide is small. In the present invention, c is 0.17 or less.

  Thus, in the present invention, the composition described by aluminum, oxygen, and hydrogen is grasped, and the oxygen content that has been conventionally recognized at once is discriminated into the oxidized content and the hydroxyl content, thereby allowing the hydroxylation. An aluminum oxide film having a high transmittance is obtained by a low degree, a high degree of oxidation, and a small amount of unreacted aluminum.

In the present invention, in order to ensure gas barrier properties, the density of the aluminum oxide film needs to be 2.5 g / cm ³ or more. When the density is low, voids or porous portions are scattered in the film, and gas molecules pass through the film through these. By forming a high-density film, there are fewer factors that allow such gas to pass through, and gas barrier properties can be secured. The upper limit of the density of the aluminum oxide film in the present invention is not particularly specified, but the density of α-alumina (steel boulder, sapphire, ruby, etc.) is 4.0 g / cm ^{3, which} is a substantial upper limit. Cracks are likely to occur in the aluminum film, and the bending resistance tends to be poor. A range of 2.5 to 3.2 g / cm ³ is preferred.

  The film thickness of the aluminum oxide film is preferably thick for gas barrier properties, but if it is too thick, light absorption cannot be ignored and cracks tend to occur in the film, so the upper limit is preferably 100 nm. In order to ensure transparency, 30 nm or less is more preferable.

  Further, although the transmittance increases if it is thin, the barrier property cannot be secured, so it is preferable to set 5 nm as the lower limit. If it is 8 nm or more, practical barrier properties can be obtained. That is, the range of 5 to 100 nm is preferable, and the range of 8 to 30 nm is more preferable.

  Next, the manufacturing method of the laminated | multilayer film of this invention is demonstrated.

  The aluminum oxide film having the composition according to the present invention can be produced by vapor deposition. For that purpose, it is necessary to advance the oxidation reaction in the vapor deposition machine to a high level, and it is important to supply sufficient oxygen as compared with the prior art.

In the present invention, at the time of vapor deposition of aluminum oxide, supplying oxygen gas of 2d to 4d (cc / m ² ) per 1 m ^{2 of} vapor deposition area with respect to the film thickness d (nm) of aluminum oxide is the laminated film of the present invention. Is preferable for use as a moisture and heat resistant gas barrier film.

The volume of oxygen gas taken into the aluminum oxide film having an area of 1 m ² and a film thickness d (nm) is calculated as follows. 2.5 g / cm ³ is the lowest value in the range of the density of aluminum oxide defined in the present invention, 102 g / mol is the formula weight of aluminum oxide Al ₂ O ₃ , and 1.5 is the equivalent ratio of oxygen gas in aluminum oxide (3 × O / Al ₂ O ₃ = 1.5 × (O ₂ / Al ₂ O ₃ )), 22400 (cc / mol) is the volume of oxygen gas per mol.

d × 10 ⁻⁹ (m) × 1 (m ² ) × 10 ⁶ (cc / m ³ ) × 2.5 (g / cm ³ ) ÷ 102 (g / mol) × 1.5 × 22400 (cc / mol) ) = 0.82d (cc).

Actually, there is oxidation of aluminum adhering to other than the film, and there is a part exhausted by a vacuum pump, and the volume of oxygen gas for completely oxidizing the deposited film needs to be 2d (cc / m ² ) or more. is there. The amount around 2.5d (cc / m ² ) is the most suitable amount, and if it is too large, the burden on the exhaust system increases, so 4d (cc / m ² ) is the upper limit.

An oxygen gas of 2.5 d (cc / m ² ) means an oxygen gas supply amount of 36 L / min when an aluminum oxide film having a thickness of 20 nm is produced on a film having a width of 2 m at a film speed of 6 m / sec. It becomes.

  The relationship between the aluminum oxide film thickness and the amount of oxygen gas is compared with the prior art using the ratio B / A of the aluminum evaporation amount A (mol / min) and the oxygen gas introduction amount B (mol / min).

  In the present invention, a boat is used for vapor deposition, and the amount of oxygen gas is defined based on the amount of aluminum oxide adhering to the film. The total amount of aluminum evaporated from the boat is about 1.25 times the amount attached to the film if the deposition efficiency in the boat vapor deposition method is 80%. In the crucible vapor deposition method used in the prior art, the deposition efficiency is as low as about 60%, so this magnification becomes larger.

  B / A according to the present invention is calculated from 1.46 to 2.91 by the following calculation.

A = d × 10 ⁻⁹ (m) × deposition area per minute (m ² / min) × 10 ⁶ (cc / m ³ ) × 2.5 (g / cm ³ ) ÷ 102 (g / mol) × 2 × 1.25
B = 2d-4d × deposition area per minute (m ² / min) / 22400.

Accordingly, B / A = 2 to 4 / {10 ⁻⁹ (m) × 10 ⁶ (cm ³ / m ³ ) × 2.5 (g / cm ³ ) ÷ 102 (g / mol) × 2 × 1.25 * 22400} = 2-4 / 1.37 = 1.46-2.91.

  In Patent Document 2, B / A is in the range of 0.2 to 0.75, and in Patent Document 1, B / A is in the range of 0.12 to 0.19. It is a very low numerical value for B / A of the present invention, and it can be seen that the amount of oxygen gas relative to the amount of aluminum of the present invention is remarkably high.

  In order to efficiently react the oxygen gas supplied in the amount shown above with aluminum to obtain a high oxidation state and high transmittance, and to obtain an excellent barrier property at a high density, aluminum vapor and oxygen gas at the time of deposition are used. Is preferably highly activated.

  As an activation method, there are various excitation methods such as plasma, ions, light, and heat. However, since plasma can be activated relatively efficiently, it is preferable to use a plasma activated vapor deposition method. As the plasma generating means, holo-cathode discharge, microwave plasma, ICP plasma, helicon wave plasma, or the like can be employed.

  FIG. 2 shows a vapor deposition machine for producing the aluminum oxide film of the present invention. The film unwound from the roll film 33 is guided to the cooling drum 35 and vapor-deposited and then wound on 34. A plasma source shown in FIG. 37 is disposed obliquely above the vapor deposition source 36, and the plasma 38 is sent into the space between the vapor deposition source and the cooling drum so as to act on the gas or vapors present in this region and activate it. . In addition, the plasma reaches the surface of the film being deposited, and activated deposition is promoted.

  Among these plasma generation means, hollow cathode discharge is suitable as a large capacity plasma generation means. The hollow cathode discharge is a method in which plasma is generated in a hollow cathode, ionization efficiency is improved by confining primary electrons in a sheath formed along the inner wall of the cavity, and the anode facing the opening of the cavity. This is a method for generating a powerful plasma in between. Depending on the width and number of aluminum evaporation sources, about five hollow cathode plasma sources are arranged per meter in the width direction of the film, and uniform activation is performed in the width direction.

As described above, the moisture and heat resistant gas barrier film of the present invention has a film thickness d (nm) of aluminum oxide in a plasma activated vapor deposition method in which high density plasma is generated in a space between an aluminum evaporation source and a polymer film. On the other hand, it is produced by depositing an aluminum oxide film on the surface of the polymer film while supplying oxygen gas of 2d to 4d (cc / m ² ) per 1 m ^{2 of} vapor deposition area. The ratio of aluminum oxide and aluminum hydroxide within the specific range according to the present invention can be achieved by taking it out into the atmosphere after the vapor deposition, and the composition can be confirmed. Moreover, it can achieve immediately after taking out in air | atmosphere after vapor deposition to make the ratio of the metal aluminum in the aluminum oxide film in this invention, aluminum oxide, and aluminum hydroxide into a specific range.

  The aluminum oxide film in which a large amount of metal aluminum according to the prior art remains is gradually oxidized and / or hydroxylated after being taken out into the atmosphere, and in a roll state, the transparency is finished in about 2 days to 1 week depending on the season. . As described above, when the amount of metallic aluminum is large, it is not completely transparent. On the other hand, the physical properties of the laminated film of the present invention are stabilized immediately after taking out into the atmosphere. Even in the roll state, it is stabilized within 24 hours. It seems that the amount of metallic aluminum that causes a reaction after deposition is small immediately after deposition, the density of the aluminum oxide film is high, the film structure is dense, and there is no room for reaction.

  The moisture and heat resistant gas barrier film of the present invention is optimal for boil and retort applications, and surface treatment using plasma or ions on the polymer film surface before vapor deposition is effective for enhancing the durability. The wet adhesion is improved by depositing aluminum oxide after the surface treatment, and it has moisture resistance enough to maintain a sufficient wet adhesion even after being exposed to high temperature and high pressure conditions in the boil or retort treatment.

  As a method for modifying the film surface, plasma treatment, reactive ion etching treatment, ion beam treatment, or the like can be applied. Among them, the plasma treatment in which oxygen plasma generated by supplying oxygen as a discharge gas to the magnetron cathode acts on the film surface can be expected to have an effective surface modification with a simple structure. In addition, the reactive ion etching process and the ion beam process can be expected to improve the moisture resistance effectively by modifying not only the surface layer of the polymer film but also a finite depth.

  As shown in FIG. 2, the plasma processing cathode is disposed between the film unwinding roll and the vapor deposition section. Since the gas pressure suitable for the treatment does not necessarily match the pressure in the vapor deposition apparatus, the surroundings may be surrounded by 42 and the pressure may be kept low by differential evacuation or kept at a higher pressure by gas supply. . Such a surface treatment unit is not particularly limited as long as it is before vapor deposition, and may be a vapor deposition chamber if there is a space to install, or may be vapor deposited by installing a roll of already processed raw material in the unwinding unit. .

  When the film surface is positively charged by this treatment and troubles occur, it may be canceled by irradiating electrons from a neutralizer as necessary. Such consideration regarding installation is also effective for reactive ion etching processing and ion beam processing.

  The laminated film of the present invention exhibits high barrier performance and durability for boil retort. For this purpose, it is effective to perform a protective coating after vapor deposition. As an example, a protective film formed by applying a liquid composed of a metal alkoxide and polyvinyl alcohol and then heat-curing exhibits good characteristics. And it can be used as an excellent packaging material for boil retort by laminating a nylon film and a heat-sealable film such as polypropylene using an adhesive.

  According to the present invention, a high-quality moist heat resistant transparent gas barrier film can be produced with high productivity.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the physical property in an Example and a comparative example was measured as follows.

(1) Total light transmittance The total light transmittance (%) of the laminated film was measured by Nippon Denshoku Industries Co., Ltd. haze meter NDH2000. If the decrease was within 1.0% with respect to the total light transmittance of the polymer film before vapor deposition, it was considered acceptable. Since the total light transmittance before vapor deposition of the polyester film which is the polymer film used in this study was 89.0%, 88.0% or more was regarded as acceptable.

(2) Oxygen transmission rate A sample cut from a laminated film to a width of 100 × 100 mm is prepared, and the oxygen transmission rate (cc / (m ² day · atm)) conforms to JISK7126-2 (established on August 20, 2006). Then, using an oxygen transmission rate measuring device OX-TRAN 2/20 manufactured by Modern Control, measurement was performed under conditions of 23 ° C. and 0% RH. The average value of 3 samples was obtained. An oxygen transmission rate of ² cc / (m ² day · atm) or less was set as an acceptable range.

(3) Water vapor transmission rate A sample cut to a width of 100 x 100 mm from the laminated film is prepared, and the water vapor transmission rate (g / (m ² day)) is modern control according to JISK7129B (established on March 20, 2008). It measured on 40 degreeC and 90% RH conditions using the water vapor transmission rate measuring apparatus Permatran-W3 / 30 by a company. The average value of 3 samples was obtained. A water vapor transmission rate of 2 g / (m ² day) or less was set as an acceptable range.

(4) Low-speed wet adhesion strength 20 parts by weight of AD-503 type adhesive for dry lamination manufactured by Toyo Morton Co., Ltd. 1 part by weight of curing agent CAT-10 type manufactured by Toyo Morton Co., Ltd. and 20 parts by weight of ethyl acetate are mixed. Then, the mixture was stirred for 30 minutes to prepare a dry laminate adhesive solution having a solid content of 19% by weight. Next, the adhesive solution was applied to the aluminum oxide laminated surface of the laminated film by a bar coating method, and dried at 80 ° C. for 45 seconds to form a 3.5 μm adhesive layer. A non-stretched nylon film “Rayfan” (registered trademark) NO1401 type (thickness 30 μm) manufactured by Toray Film Processing Co., Ltd. is layered on the adhesive layer surface, and heat roll using “Lami Packer” (LPA330) manufactured by Fuji Tech Co., Ltd. Were bonded together by heating to 40 ° C. Next, an unstretched polypropylene film “Treffan” (registered trademark) NO ZK100 type (thickness: 70 μm) was bonded by the same method. This laminate film was aged in an oven heated to 40 ° C. for 2 days to cure the adhesive.

  A cut sample was prepared by cutting the laminate film into a 15 cm square. Two cut samples were overlapped so that the unstretched polypropylene film faces each other, and a heat sealer was used to heat-seal the edge 10 mm of each of the three sides to prepare a 150 mm square package.

  Next, the package was retorted at a temperature of 135 ° C. for 30 minutes using an autoclave (SR-24 type) manufactured by Tommy Seiko Co., Ltd.

  After the retort treatment, cut the package into 15mm width and 150mm length to make a cut sample, and use “Tensilon” (PTM50 type) manufactured by Orientec Co., Ltd., with the interface between laminated film and nylon film as the interface. While applying water with a cotton swab, the film was peeled off at a pulling rate of 50 mm / min by the 180 ° peel method, and the strength was measured. These measurements were performed using two different cut samples, and the average value obtained was defined as the low-speed wet adhesion strength (N / 15 mm) after retorting. 1.5 N / 15 mm or more was regarded as acceptable.

(5) Composition analysis The composition of the aluminum oxide film was measured using high-resolution Rutherford backscattering and high-resolution hydrogen forward scattering (HR-RBS / HR-HFS). The measuring apparatus used was HRBS500 manufactured by Kobe Steel, Ltd. In HR-RBS, helium ions were implanted and the backscattering was measured. In HR-HFS, nitrogen ions were used to measure forwardly scattered hydrogen atoms.

  Since a composition distribution in the film thickness direction can be obtained from the distribution of the scattering intensity, the average value in a relatively stable region near the center was taken as the composition value. In the sample having a thickness of 20 nm, 6 nm to 11 nm was set as the calculation region. And about the sample from which film thickness differs, it was set as the calculation area | region according to this.

(6) Density measurement The total reflection X-ray method was used for the measurement of the density of the aluminum oxide film. In order to ensure the flatness of the sample, a 125 μm-thick biaxially stretched polyethylene terephthalate film (“Lumirror” (registered trademark) T60, manufactured by Toray Industries, Inc.) was connected to the roll film and deposited as the same continuous roll film. For the measurement, a multi-functional X-ray evaluation apparatus for ATX-G type surface structure evaluation manufactured by Rigaku Corporation was used. As X-rays, CuKα rays having a wavelength of 0.15405 nm generated from a copper target were used. Surface reflection was measured from an angle of 2θ of 0.05 ° to 4 °, and the density was calculated from the critical angle of total reflection.
(Reference Table Kazuhiko Journal of Surface Analysis Vol. 9, No. 2 (2002) P.203).

Example 1
A biaxially stretched polyethylene terephthalate film for packaging (“Lumirror” (registered trademark) P60, thickness 12 μm, width 2000 mm) manufactured by Toray Industries, Inc. is set as a polymer film in the film unwinding portion, and an ultimate pressure of 8 A vacuum was drawn up to × 10 ⁻³ Pa.

As a thin film formation mechanism, an aluminum wire was sent on a resistance-heated boat to evaporate it, and oxygen gas was allowed to flow at a flow rate of 36 L / min for reactive deposition. The film speed was made to run at 6 m / second, and the supply speed of the aluminum wire was adjusted so that the film thickness of the aluminum oxide film was 20 nm. The amount of oxygen gas per 1 m ^{2 of the} aluminum oxide film was 50 cc, and the relationship was 2.5 cc / nm with respect to the film thickness (nm) of the aluminum oxide. The temperature of the film cooling drum at this time was −20 ° C.

  A magnetron cathode with copper as a target was disposed between the film unwinding roll and the vapor deposition section, oxygen was supplied, and a high frequency voltage of 500 kHz was applied for discharge to excite oxygen plasma. This plasma was applied to the surface of the polyester film, and a plasma treatment was performed on the film surface before vapor deposition.

  There is a plasma generator obliquely above the vapor deposition source, and the plasma was excited by flowing argon gas through a hollow cathode type plasma source and discharging it. The plasma was pulled out by the anode facing the boat directly above the boat to activate aluminum atoms and oxygen gas toward the film surface.

  After vapor deposition, it was possible to obtain a moisture and heat resistant gas barrier film having high transparency of 88.7% and excellent gas barrier performance. The values of a, b, and c are indicated by point 20 in FIG.

(Example 2)
In the same manner as in Example 1, the film speed was 4 m / sec, the oxygen gas flow rate was lowered to 24 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film was kept at 50 cc, and the film thickness of the aluminum oxide film was Adjusted to 22 nm. Since the power input to the hollow cathode plasma source was the same as in Example 1, an aluminum oxide film was deposited under stronger activation conditions than in Example 1.

(Example 3)
In the same manner as in Example 1, the film speed was set to 8 m / sec, the oxygen gas flow rate was increased to 48 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film was kept at 50 cc, and the film thickness of the aluminum oxide film was changed. Adjusted to 19 nm. Since the input power to the hollow cathode plasma source was the same as in Example 1, an aluminum oxide film was deposited under a weak activation condition as compared with Example 1.

Example 4
In Example 1, only the oxygen gas flow rate was reduced to 32 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film was set to 44 cc, and the oxygen gas was less than 2.2 cc / nm with respect to the aluminum oxide film thickness (nm). An aluminum oxide film was deposited under the following conditions. Although the total light transmittance decreased, it was within the acceptable range.

(Example 5)
In Example 1, the film speed was 10 m / sec, the oxygen gas flow rate was 30 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film was 25 cc, and the film thickness of the aluminum oxide film was 10 nm. An aluminum oxide film was deposited under the same oxidation conditions as in Example 1 at 2.5 cc / nm with respect to the film thickness (nm). Since the film thickness was low, the gas barrier property was lowered, but it was within the acceptable range.

(Comparative Example 1)
In the same manner as in Example 1, an aluminum oxide film was deposited under the condition that activation by a hollow cathode plasma source was not performed. The density was as low as 2.2 g / cm ³ and the gas barrier property was rejected. The values of a, b, and c are indicated by point 21 in FIG.

(Comparative Example 2)
In Example 1, instead of activation by a hollow cathode plasma source, parallel plate stainless steel electrodes are made to face each other on a boat, a high frequency voltage is applied between the electrodes to plasma between the electrodes, and aluminum vapor is passed between them. An aluminum oxide film was deposited. The density was as low as 2.4 g / cm ^3, and the gas barrier property was rejected (Comparative Example 3).
In Example 1, the oxygen flow rate was 25 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film was 35 cc, and the oxygen gas was 1.7 cc / nm with respect to the aluminum oxide film thickness (nm) and the oxygen gas was small. An aluminum oxide film was deposited. The film had a large a value and a large amount of metal aluminum, resulting in a decrease in total light transmittance and failure.

(Comparative Example 4)
In Example 1, the oxygen flow rate is 22 L / min, the oxygen gas amount per 1 m ^{2 of the} aluminum oxide film is 31 cc, and the oxygen gas is 1.5 cc / nm less than the aluminum oxide film thickness (nm). An aluminum oxide film was deposited. After taking out the roll in the atmosphere, it was rolled up in an atmosphere of 65% RH and 25 ° C., and aged for 5 days in the same atmosphere to promote transparency, but the total light transmittance was insufficient. became.

  Table 1 shows the production conditions of Examples and Comparative Examples, the physical properties of the aluminum oxide film of the laminated film, the composition, the composition fraction, and the characteristics of the laminated film.

11 Line indicating b + 2c = 1 12 0.5 × Al + 0.5 × Al (OH) ₃
13 0.15 × Al + 0.7 × AlO _1.5 + 0.15 × Al (OH) ₃
14 a = 0
15 b = 0
16 c = 0
17 a = 0.07
18 c = 0.17
19 Range of (a, b, c) in the present invention 20 Example 1
21 Comparative Example 1
31 Vacuum tank 32 Vacuum pump 33 Unwinding roll 34 Winding roll 35 Cooling drum 36 Evaporating source 37 Plasma generating part hollow cathode 38 Plasma 39 Anode 40 Oxygen nozzle 41 Plasma processing cathode 42 Enclosure of plasma processing part

Claims (5)

An aluminum oxide film is laminated on the surface of at least one side of the polymer film, and the fractions of the number of aluminum atoms attributable to metal aluminum, aluminum oxide, and aluminum hydroxide in the aluminum oxide film are a, b, c (a + b + c = When represented by 1), a laminated film in which a is in the range of 0 to 0.07, c is in the range of 0 to 0.17, and the density of the aluminum oxide film is 2.5 g / cm ³ or more. .   The film thickness of the said aluminum oxide film exists in the range of 5-100 nm, The laminated | multilayer film of Claim 1 characterized by the above-mentioned. The method for producing a laminated film according to claim 1 or 2, wherein a film thickness of aluminum oxide is obtained by using a plasma activated vapor deposition method in which high density plasma is generated in a space between an evaporation source of aluminum and the polymer film. An aluminum oxide film is laminated on the surface of a polymer film while supplying 2d to 4d (cc / m ² ) of oxygen gas per 1 m ^{2 of} vapor deposition area with respect to d (nm). Method.   The method for producing a laminated film according to claim 3, wherein the high-density plasma is generated by a hollow cathode plasma source. The method for producing a laminated film according to claim 3 or 4, wherein the polymer film is subjected to a surface treatment using plasma or low energy ions, and aluminum oxide is laminated thereon.

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