JP5720315B2 - Evaluation method of vapor deposition film - Google Patents

Description

  The present invention relates to a vapor-deposited film having gas barrier properties, and more particularly to a vapor-deposited film in which an inorganic compound layer is formed on at least one surface of a packaging film for fresh food, processed food, medical products, medical equipment, electronic parts and the like. .

  In the field of packaging materials such as food, medicine and pharmaceuticals, and electronics such as resin substrates for flat panel displays such as liquid crystal and organic EL, it is required to have a high gas barrier property. From this point of view, a gas barrier film in which a metal such as aluminum or a metal oxide such as silicon oxide, aluminum oxide, and magnesium oxide is vacuum-deposited on a polymer film substrate is used.

  Among metal oxides having gas barrier properties, silicon oxide is particularly excellent in gas barrier properties, and silicon, which is a raw material, is abundant on the earth, so it is traded inexpensively and supply is stable.

  On the other hand, sputtering methods, ion plating methods, CVD methods, vacuum deposition methods, and the like can be cited as methods for forming a film in a vacuum, but vacuum deposition methods are the most excellent in terms of film formation speed and cost. In particular, the electron beam method is effective in that the film formation rate can be easily controlled by the irradiation area, the electron beam current, and the like, and the material can be heated locally, so that heat can be applied in a short time.

  In the production of vapor-deposited films by the electron beam vacuum deposition method, it is common to deposit a large amount of vapor-deposited films at once by depositing on a long and wide base film using a roll-up type vapor deposition machine. It is. In the case of production using a wind-up type vapor deposition machine, the number of windings m of the base film is several hundreds m for a small vapor deposition machine and tens of thousands m for a large vapor deposition machine. The width of the base film is less than 1 m for a small vapor deposition machine, but about 2 m for a large film.

  In production, it is necessary to process the film while controlling the film thickness, light transmittance, and the like according to the purposes such as barrier properties and transparency. Control items include current, pattern, irradiation area, etc. even with an electron beam alone, and control is not easy because the evaporation process varies depending on the material even under the same conditions. In particular, when processing with a long length, it is necessary to form a constant film from the start to the end of film formation. When processing with a wide width, it is desirable to perform processing while suppressing variations in the width direction as much as possible. In addition, it is desirable to increase the film winding speed as much as possible in order to shorten the processing time for cost reduction.

  Regarding the control of film formation in the width direction, a proposal has been made in Patent Document 1. However, since two or more electron beams are required for a deposition processing width of 500 mm or more, the process becomes complicated and the cost is increased. In addition, there is a problem in ensuring uniformity of the deposited film quality. In terms of material, Patent Document 2 proposes that the ratio of two kinds of vapor deposition components in the material is inclined in the height direction, but this is not a method suitable for mass production.

On the other hand, not only the electron beam evaporation method, but also when the evaporation of the evaporation source cannot be controlled sufficiently, not only uniform film formation but also splash is likely to occur, greatly affecting the physical properties of the film. Effect. Since a hole is formed in the barrier film, the barrier is lowered, or a splash mark remains on the film, and when ink or the like is coated on the film, the splash mark appears as a pattern. In addition, when using a vapor-deposited film as a packaging material, in addition to the subsequent coating process, laminating process, and slitting process,
When processing into a packaging bag, the film may have to be bent or bent. If there is such a process, a burden is applied to the barrier layer including the vapor deposition film, and the layer is cracked, leading to a significant decrease in barrier properties. These cracks are somewhat dependent on physical properties such as the hardness of the barrier film, but are usually generated when the film is unable to withstand the tension of the tension and is torn. At this time, if the splash mark exists on the film, a crack enters from the splash mark, so that the crack is further increased. Since this is an undesirable phenomenon as a product, reducing splash is important in vapor deposition.

  On the other hand, a vapor deposition film using SiOx as a vapor deposition film has excellent barrier properties and low cost, and is much more transparent than aluminum and aluminum vapor-deposited products. Therefore, silicon oxide and silicon are used as general-purpose materials. Yes. However, a vapor deposition film using SiOx as a vapor deposition film has a yellow color, and when used as a protective film for a packaging material or a display medium, it is difficult to grasp the correct color (see Patent Documents 3 and 4). .

Japanese Patent Laid-Open No. 9-287074 JP-A-11-189864 Japanese Patent Laid-Open No. 3-100164 JP-A-4-333767

  It is an object of the present invention to provide a low-cost and high gas barrier property in a deposited film comprising a polymer film substrate and an inorganic compound layer formed by depositing SiOx on at least one surface of the substrate by an electron beam vacuum deposition method. It is excellent in transparency and it is difficult to generate cracks in the deposited film, and a deposited film is provided.

The present invention is for solving the above-mentioned problems. The invention according to claim 1 of the present invention is a substrate comprising a polymer film, and at least one surface of the substrate is made of SiO 2 by electron beam vacuum deposition. _In a vapor deposition film comprising an inorganic compound layer formed with _x , the yellowness (YI) measured by stacking five vapor deposition films having a vapor deposition film thickness of 15 to 35 nm is 30 or less, and the vapor deposition This is a method for evaluating a deposited film , based on the fact that the crack initiation strain [%] of the film is 2.5% or more.

  According to the present invention, in a deposited film comprising a polymer film substrate and an inorganic compound layer in which SiOx is formed on at least one surface of the substrate by an electron beam vacuum deposition method, cracks in the deposited film are less likely to occur. A vapor-deposited film having excellent transparency can be provided.

The schematic of the tensile testing machine which measures the crack generation start distortion amount (%) based on this invention is shown.

  Details of the present invention will be described below. The vapor-deposited film of the present invention is a vapor-deposited film in which SiOx is formed by electron beam vacuum vapor deposition on at least one surface of the polymer film substrate, and the crack initiation strain amount of the vapor-deposited film ( %) Is 2.5% or more, and the yellowness (YI) measured by stacking five deposited films is 30 or less.

  The crack initiation strain (%), which is a guideline for predicting the occurrence of cracks in the deposited film, will be described later in detail with respect to the measurement method, etc., but from the experimental value, the crack initiation strain (%) is 2.5% or more. If so, the generation of cracks is extremely suppressed and high quality can be obtained. On the other hand, if this value is less than 2.5%, the occurrence rate of cracks becomes high and the quality as a product cannot be guaranteed.

  In addition, the yellowness (YI), which is a measure of the transparency of the deposited film, is measured using a chromaticity meter. However, if the yellowness (YI) is 30 or less, the transparency is excellent. Can be adjusted without any problems. On the other hand, if the yellowness (YI) exceeds 30, the coloration can be clearly discerned visually, and the color tone when it becomes a final product such as a packaging material becomes unstable. There are problems that become difficult, and the higher the transparency, the better the freshness of the contents.

  The polymer film substrate used in the present invention is not particularly limited. For example, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polystyrene A film, a polyamide film, a polyvinyl chloride film, a polycarbonate film, a polyacrylonitrile film, a polyimide film and the like are used, and those having mechanical strength and dimensional stability are preferable. In particular, a biaxially stretched polyethylene terephthalate (PET) film is preferably used.

  The surface of the polymer film substrate may contain antistatic agents, UV inhibitors, plasticizers, lubricants, etc. Corona treatment, low-temperature plasma treatment as pretreatment to improve adhesion to the thin film You may give it.

  In addition, an anchor made of a non-aqueous resin such as acrylic polyol, polyester or isocyanate compound, water-soluble resin such as polyvinyl alcohol (PVA), starch, cellulose, polyacrylic acid or ethylene vinyl alcohol resin on the surface of the polymer film substrate A coating layer may be provided, which not only improves the adhesion between the substrate and the thin film, but also forms a thin film without defects by smoothing the surface, and further eliminates minute barrier defects in the deposited thin film layer. It can assist and improve the barrier property.

An overcoat layer may be provided on the thin film layer of SiOx, and the presence of the overcoat layer protects the vapor-deposited film which tends to be hard and brittle and prevents cracks due to rubbing and bending.

  The thickness of the polymer film substrate is not particularly limited, but considering the suitability as a packaging material and the possibility of laminating other layers, a thickness of 6 to 30 μm is preferable.

The thin film layer of SiOx formed by the present invention can be obtained by using silicon oxide and silicon as an evaporation source for electron beam vacuum deposition. There are mainly two types of silicon oxide, SiO and SiO _{2. Since} SiO is manufactured using SiO ₂ as a raw material, the cost increases. Therefore, it is desirable to form a film without using SiO. The material may be limited to only one type of powder, but the price is particularly low, and in a material in which two types of Si and SiO ₂ are mixed, the evaporation process and the value of x of SiOx can be easily controlled, that is, a film Easy to control thickness and transparency. While SiO is sublimable, Si and SiO ₂ are considered to be affected by the characteristics of melting and vitrification. When SiO is used as a vapor deposition material, it is usually a lump, and when sublimated during vapor deposition, it may be blown off as a lump, which is presumed to lead to a lot of splash.

  As the shape of the evaporation source, powder, granule, molded body or the like is used. Since the granules and the molded body are manufactured from powder, the best cost merit is powder. However, since powder has poor handling properties and is difficult to uniformly fill the crucible into which the evaporation source is inserted, there is a problem that the shape of the evaporation source is not stable, and a molded body is generally desirable.

The particle size of the powder used is not particularly limited. In general, Si has an average particle diameter of about 6 to 20 μm, and SiO ₂ has a grade of about 1 to 20 μm. The characteristics such as whether the average particle size and the peak of the particle size distribution are sharp or wide affect the dispersibility, material bulk density, evaporation process, etc., so selection is necessary. When two or more grades are mixed and used, attention must be paid to the combination.

  With respect to the material bulk density, when the same vapor deposition film thickness is obtained from the same volume of material, the material with a smaller bulk density simply decreases more rapidly in the volume of the material. Therefore, it can be said that the smaller the bulk density is, the more the material is bottomed and the bottom is easily shot with an electron beam. For this reason, the material feeding speed must be increased, which not only affects the vapor deposition process, but also causes a case where the material cannot be processed in a long length because the material is lost in a short time. On the other hand, if the bulk density is too high, it takes time to heat the material with an electron beam, even if the material is slowly reduced, and there is a risk that the start of evaporation will be delayed. If the material bulk density is too high or too low, a problem occurs. Therefore, it is desirable that the material bulk density is appropriately designed according to the specifications of the production machine and the vapor deposition film.

  The method of manufacturing the molded body of the evaporation source includes a method of performing only molding such as a casting method and a rubber press method, and a method of performing pressure sintering simultaneously with molding such as a hot press method and a hot isostatic pressing method (HIP). There is. When the latter method is used, the temperature at which densification occurs is lowered and a high-density sintered body having a uniform particle size without abnormal grain growth can be obtained. However, the present invention is not particularly limited. The atmosphere during sintering includes a vacuum atmosphere, a nitrogen atmosphere, an argon atmosphere, an air atmosphere, and the like. In the present invention, the atmosphere during sintering is not particularly limited. However, since the main component of the SiOx thin film layer to be formed is Si or O, it is desirable that the gas in the atmosphere does not react with the vapor deposition material.

X of the SiOx thin film layer to be formed is an O / Si ratio in the thin film layer and takes a numerical value of 1 to 2. The closer the value is to 2, the closer the property is to SiO ₂ , but the transparency increases, but the barrier property is lacking. However, when the value is close to 1, the barrier property increases, but the film is yellow and the transparency is lacking. There is a relationship. This is because, as a principle of the vapor deposition method, heated and evaporated SiOx is physically deposited on the base film, and as a result, the gap at the time of deposition becomes a factor that determines the gas barrier performance. Therefore, if the value of x is small, the inter-atomic network of SiOx on the film becomes dense and gas barrier properties appear, and conversely, if the value of x is large, the interatomic network becomes sparse and gas barrier properties do not appear. The On the other hand, if the value of x is small, the amount of Si that is an inorganic substance increases, and if the value of x is large, the amount of Si decreases. Therefore, the larger the value of x as the hardness of the film, the more flexible the film is. Therefore, it is considered that the resistance value when force is applied to the deposited film layer is stronger when the value of x is larger and cracks, that is, cracks are more likely to occur.

  The crack generation start strain amount (%) in the present invention includes a fixed stage 3 fixed on the base 2 and a movable stage 4 movable in the horizontal direction on the base 2 as shown in FIG. Measured with the tensile tester 1. First, as a measurement sample, one end of the transparent barrier film 10 of the present invention composed of the transparent base material 102 and the barrier thin film 104 is fixed to the fixing stage 3 of the tensile tester 1, and then the sample Is fixed to the movable stage 4. Note that the thickness of the transparent substrate 102 is preferably set to 12 μm, and the thickness of the barrier thin film 104 is preferably set to 25 nm.

  Next, the movable stage 4 is moved on the base 2 in the horizontal direction at a speed at which the following strain amount is 0.01% per second, and a tensile force is applied to the sample (transparent barrier film 10) of the present invention. The state of the barrier thin film 104 on the transparent substrate 102 at this time is observed at a magnification of 100 times by the microscope observation device 5 installed above. The measurement is terminated when crack fracture is observed in a direction perpendicular to the tensile direction by the movable stage 4. The strain amount of the sample (transparent barrier film 10) at the end of measurement, that is, {(length after tension of sample 10−length before measurement of sample 10) / length before measurement of sample 10} × 100 ( %) Is the crack initiation strain (%) in the present invention.

  Therefore, in order to obtain an appropriate x value according to the purpose, it is necessary to set vapor deposition material prescription and vacuum vapor deposition machine conditions. For example, with a vapor deposition material, the higher the O / Si ratio of the material, the higher the O / Si ratio of the deposited film. Under mechanical conditions, for example, oxygen or water can be appropriately introduced and adjusted in the film formation chamber during vacuum deposition, but the pressure in the film formation chamber may increase so that the electron beam cannot be used. Yes, it is difficult to establish technology.

  As a result of diligent efforts, the inventors have found that a vapor-deposited film that is less prone to cracking of the vapor-deposited film and excellent in transparency can be obtained when the O / Si ratio is in the range of 1.4 to 1.9. . The vapor deposition film having an O / Si ratio of less than 1.4 tends to be deeply colored due to a large amount of Si, and when the O / Si ratio exceeds 1.9, the barrier property tends to decrease due to the large amount of O. There is.

  Hereinafter, the present invention will be described in more detail with examples.

<Example 1>
Si (average particle size 10 μm) and SiO ₂ (average particle size 8 μm) are mixed so that the O / Si ratio of the material is 1.4, water and silica sol are further mixed, slurry is prepared, Poured into molds and molded respectively. This molded product was dried and heat-treated to obtain a vapor deposition material. Further, using the electron beam heating type wind-up type vapor deposition apparatus, the produced vapor deposition material was vacuum-deposited on a 12 μm thick polyester film at a winding speed of 200 nm · m / s and a vapor deposition width of 480 mm. A film was obtained.

<Example 2>
Except that the O / Si ratio of the powder of the vapor deposition material was 1.75, a molded body was prepared and vapor-deposited by the same method as in Example 1 to obtain a vapor-deposited film of Example 2.

<Example 3>
Except that the powder of the vapor deposition material had an O / Si ratio of 1.65, a molded body was prepared and vapor deposited by the same method as in Example 1 to obtain a vapor deposited film of Example 3.

<Example 4>
Except having used the polyester film provided with the anchor coat layer which consists of polyurethane-type resins as a vapor deposition base material, the molded object was created and vapor-deposited by the same method as Example 1, and the vapor deposition film of Example 4 was obtained. .

<Example 5>
Except that an overcoat layer made of a water-soluble polymer was provided on the vapor deposition film, a molded body was prepared and vapor-deposited by the same method as in Example 4 to obtain a vapor deposition film of Example 5.

<Comparative Example 1>
Except that the O / Si ratio of the vapor deposition material powder was 1.1, a molded body was prepared and vapor deposited by the same method as in Example 1 to obtain a vapor deposition film of Comparative Example 1.

<Comparative Example 2>
Except that 20% of the powder of the vapor deposition material of Example 1 was changed to SiO, a molded body was prepared and vapor-deposited by the same method as Example 1 to obtain a vapor deposition film of Comparative Example 3.

<Comparative Example 3>
Except that the powder of Example 1 had an O / Si ratio of 1.42, a molded body was prepared and vapor-deposited by the same method as Example 1 to obtain a vapor-deposited film of Comparative Example 5.

<Evaluation method>
Using the respective vapor deposition films obtained in Examples 1 to 5 and Comparative Examples 1 to 3, the following apparatus and method were used to measure the O / Si ratio, oxygen permeability, water vapor permeability, yellowness (YI) and The crack initiation strain (%) was measured. The obtained results are shown in Table 1.
O / Si ratio-Measure film composition at center of vapor deposition width with XPS (JPS-90SXV, manufactured by JEOL Ltd.) Oxygen permeability (ml / m ² · day · MPa)-Oxygen permeability measuring device
(OXTROXTRAN 2/20, manufactured by mocon, 30 ° C, 70% RH)
Water vapor permeability (g / m ² · day) to water vapor permeability measuring device
(PERMATRAN 3/30, manufactured by mocon, 40 ° C./90% RH)
Yellowness (YI) Measured with a color difference meter Crack initiation strain (%) Measured with tensile tester 1

<Comparison result>
The products of the present invention obtained in Examples 1 to 5 all have a YI value of 30 or less, a crack generation starting strain amount of 2.5% or more, and excellent oxygen permeability and water vapor permeability. was gotten. On the other hand, the comparative products obtained in Comparative Examples 1 to 3 had a YI value exceeding 30 and a crack initiation strain amount of less than 2.5%, and all of the present invention showed good results.

DESCRIPTION OF SYMBOLS 1 .... Tensile tester 2 .... Base 3 .... Fixed stage 4 .... Movable stage 5 .... Microscope observation device 10 .... Sample (transparent barrier film)
102... Transparent substrate 104... Barrier thin film

Claims (1)

In a vapor deposition film comprising a base material made of a polymer film and an inorganic compound layer in which SiO _x is formed on at least one surface of the base material by an electron beam vacuum vapor deposition method, the vapor deposition thickness is 15 to 35 nm. Vapor deposition film having a yellowness (YI) measured by stacking 5 vapor deposition films of 30 or less and a crack generation starting strain [%] of the vapor deposition film being 2.5% or more as a measurement standard. Evaluation method.

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