Transparent barrier film

Abstract

The present invention aims to provide a transparent barrier film with excellent barrier performance by forming a dense inorganic oxide layer with few defects without performing an anchor coat or the like on a biaxially oriented polyester film. 【Solution means】 The present invention is a biaxially oriented polyester roll film for laminating an inorganic oxide, which is used for a laminate obtained by laminating an inorganic oxide on at least one side of a biaxially oriented polyester film. The surface for laminating the inorganic oxide satisfies the following requirements (1) to (4), and the winding hardness of the roll film has an R value of 25 or less and 15 or more with a rebound hammer. It is a biaxially oriented polyester roll film characterized by this. Also, it is a transparent barrier film formed by laminating an inorganic oxide. (1) The number of fine protrusions with a height of less than 3 nm per area of 4×10 , , , -12 , 2 , 2 m 2 is 250 or more and 600 or less. (2) The number of fine protrusions with a height of 3 nm or more per area of 4×10 -12 m 2 is 300 or more and 600 or less. (3) The arithmetic mean height Sa is 0.010 μm or more and 0.025 μm or less. (4) The contact angle of diiodomethane is 23° or more.

Description

[Technical Field]

[0001] This invention relates to a transparent barrier film that has excellent properties as a packaging material for food, pharmaceuticals, electronic components, etc., requiring airtightness, or as a gas-blocking material, possessing superior transparency, gas barrier properties, printability, and flexibility. [Background technology]

[0002] Transparent barrier films are used in which inorganic oxides are laminated onto plastic films. Metal oxides are frequently used as inorganic oxides due to their transparency. In particular, films laminating silicon oxide, aluminum oxide, and mixtures thereof using vapor deposition or CVD methods are mainly commercially available. (See, for example, Patent Document 1.) However, some parameters, such as water vapor transmission rate (WVTR) and oxygen transmission rate (OTR), were insufficient when measured using the vapor deposition method.

[0003] One way to improve the barrier properties of barrier films is to adjust the surface roughness of the plastic film on which the inorganic oxide is laminated, thereby reducing the amount of static charge. Furthermore, there are methods to increase the wetting tension to 50 mN / m or more through corona treatment, etc. (See, for example, Patent Document 2). In other words, the thin film formed by the vapor deposition method prevents defects from forming in the thin film layer by creating discharge marks on the surface due to the discharge of extremely thin, charged static electricity, resulting in irregularities. However, the amount of charge generated during peeling depends on how closely the films are adhered to each other and how quickly they are peeled apart. Surface roughness is one factor that controls the adhesion between the films, but it is not sufficient. Furthermore, wetting tension is measured using a mixed solution of reagents, and according to JIS standards, it is measured using solutions with varying mixing ratios of ethylene glycol monoethyl ether, formamide, methanol, and water. No direct relationship has been observed between the wettability of these reagents and the barrier performance of the thin film. Furthermore, immediately after film creation, the wet tensile strength is high due to the effect of corona treatment, but this effect diminishes over time. In polyamide resin films, there are laminates in which an inorganic oxide layer is laminated and a sealant film is laminated, after applying corona treatment or the like to reduce the water contact angle to 70° or less and the diiodomethane contact angle to 35° or less, preferably 10 to 20°. This improves the barrier stability against retort treatment. (See, for example, Patent Document 3) It behaves differently from the surface properties of biaxially oriented polyester film.

[0004] There are descriptions of transparent barrier films with low helium gas permeability due to the composition of the inorganic thin film layer and treatment in water vapor gas. (See, for example, Patent Document 4.) This technique involves adjusting the composition of the inorganic thin film layer and treating it in water vapor to increase its density and reduce helium gas permeation. However, it does not consider how density is affected by the surface chemical conditions of the substrate. Furthermore, although it is understood that defects in the inorganic thin film layer cause a decrease in barrier function, the cause of these defects has not been investigated, and no improvements have been made. In addition, the amount of argon gas permeation is not specified, and defects in the inorganic oxide layer have not been evaluated. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 2638797 [Patent Document 2] International Publication No. WO2022-168703 [Patent Document 3] Japanese Patent Application Publication No. 10-52879 [Patent Document 4] Japanese Patent Publication No. 2014-65292 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The inventors of the present invention have investigated these technical problems. The objectives of the present invention are to provide a transparent barrier film with excellent barrier performance by forming a dense inorganic oxide layer with few defects on a biaxially oriented polyester film without the need for anchor coating or the like, and to provide a suitable biaxially oriented polyester roll film for forming the inorganic oxide layer by means such as vapor deposition. [Means for solving the problem]

[0007] The inventors of this invention have diligently investigated the optimal surface condition and winding state of the biaxially oriented polyester roll film, which is the raw material, in order to improve the barrier properties of a transparent barrier film laminated with an inorganic oxide layer. They have discovered a biaxially oriented polyester film with a surface condition that densifies the inorganic oxide layer, leading to the present invention. In other words, a biaxially oriented polyester roll film for use in a laminate formed by laminating an inorganic oxide on at least one side of a biaxially oriented polyester film, characterized in that the surface on which the inorganic oxide is laminated satisfies the following requirements (1) to (4), and the winding hardness of the roll film is such that the R value is 25 or less and 15 or more when measured with a reband hammer. (1) Area 4×10 -12 m 2 The number of microscopic protrusions less than 3 nm in height per surface is between 250 and 600. (2) Area 4×10 -12 m 2 The number of microscopic protrusions with a height of 3 nm or more per unit area is between 300 and 600. (3) The arithmetic mean height Sa is between 0.010 μm and 0.025 μm. (4) The contact angle of diiodomethane is 23° or greater.

[0008] Furthermore, the biaxially oriented polyester roll film is characterized in that, more than 200 days after manufacture, the contact angle of diiodomethane on the film surface where inorganic oxides are laminated remains at 23° or higher.

[0009] Further, a transparent barrier film obtained by laminating an inorganic oxide on the biaxially oriented polyester roll film.

[0010] In the above-described transparent barrier film, the relationship obtained by dividing the ratio of the helium gas permeability of the transparent barrier film by the permeability of the roll film and then dividing by the ratio of the argon gas permeability of the transparent barrier film to the argon permeability of the roll film satisfies the following [Formula 1], and the argon permeability is less than 10 mL (stp) / m 2 ·24 h·MPa. The transparent barrier film is characterized by this. (PtHe / PfHe) / (PtAr / PfAr) ≦ 2.0 ··· [Formula 1]

[0011] Also, a method for producing the above-described transparent barrier film, characterized in that the biaxially oriented polyester roll film is subjected to argon plasma treatment and then an inorganic oxide is laminated.

Advantages of the Invention

[0012] According to the present invention, a transparent gas barrier film that is inexpensive, has excellent transparency, can maintain stable barrier properties, and enables long-term storage of contents can be provided, and a biaxially oriented polyester roll film suitable for producing the transparent gas barrier film can be provided.

Brief Description of the Drawings

[0013] [Figure 1] Take-up roll [Figure 2] Evaporation device [Figure 3] Contact angle measurement method

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described. The biaxially oriented polyester film in the present invention is composed of a polyester resin composition containing the following polyester resin as a main component. The polyester resin constituting the biaxially oriented polyester film of the present invention is a polymer synthesized from a dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative. Examples include polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, with polyethylene terephthalate being preferred from the viewpoint of mechanical properties, heat resistance, and cost. Here, "main component" means that the content in the polyester resin composition is 80% by weight or more, preferably 90% by weight or more, more preferably 95% by weight or more, and most preferably 98% by weight or more.

[0015] The polyester resin constituting the biaxially oriented polyester film of the present invention can be produced by conventionally known methods. For example, it can be produced by esterifying terephthalic acid (TPA) with ethylene glycol (EG) followed by polycondensation, or by performing a transesterification reaction between an alkyl ester of terephthalic acid, such as dimethyl terephthalate, and ethylene glycol, followed by polycondensation. The polymerization apparatus may be batch-type or continuous-type.

[0016] Furthermore, it is preferable that the polyester resin used in the biaxially oriented polyester film of the present invention avoids the use of conventional antimony compounds such as antimony trioxide as polymerization catalysts, as described later. By not using antimony compounds as the main polymerization catalyst when manufacturing the polyester resin, and instead using aluminum compounds as described later, a polyester film with excellent hygiene and printability can be obtained. In addition, the contact angle of diiodomethane after corona treatment is also increased and its decrease over time is minimal.

[0017] Next, the polymerization catalyst used in producing the polyester resin used in the biaxially oriented polyester film of the present invention will be described. The polymerization catalyst used in the present invention is a polymerization catalyst characterized by having the ability to promote esterification. In the present invention, as will be described later, it is preferable to avoid using polymerization catalysts of antimony compounds such as antimony trioxide that have been conventionally used. As such a polymerization catalyst, a polymerization catalyst containing at least one selected from aluminum compounds and at least one selected from phosphorus compounds is preferred.

[0018] When synthesizing the polyester resin used in the biaxially oriented polyester film of the present invention, any known aluminum compound can be used without limitation as the aluminum compound constituting the polymerization catalyst.

[0019] Examples of aluminum compounds include, specifically, aluminum acetate, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum chloride hydroxide, and organoaluminum compounds such as aluminum acetylacetonate and aluminum oxalate, as well as their partial hydrolysates. Of these, carboxylates, inorganic acid salts, and chelate compounds are preferred, with aluminum acetate, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum chloride hydroxide, and aluminum acetylacetonate being more preferred, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, and aluminum chloride hydroxide being even more preferred, and aluminum acetate and basic aluminum acetate being the most preferred.

[0020] The amount of aluminum compound used in the polymerization catalyst for the polyester resin used in the biaxially oriented polyester film of the present invention is preferably such that 1 to 80 ppm remains as aluminum atoms relative to the total mass of the obtained polyester resin, more preferably 2 to 60 ppm, even more preferably 3 to 50 ppm, particularly preferably 5 to 40 ppm, and most preferably 10 to 30 ppm. If the level falls below the above threshold, catalytic activity may be impaired, and if it exceeds the threshold, aluminum-based foreign matter may be generated. Since almost 100% of the aluminum compound used remains even when subjected to a reduced pressure environment during polyester polymerization, it is reasonable to consider the amount used as the amount remaining.

[0021] The phosphorus compounds used as polymerization catalysts are not particularly limited, but phosphonic acid compounds and phosphinic acid compounds are preferred because they significantly improve catalytic activity, and among these, phosphonic acid compounds are particularly preferred because they significantly improve catalytic activity.

[0022] Among these phosphorus compounds, phosphorus compounds having a phenol moiety within the same molecule are preferred. While there are no particular limitations as long as the phosphorus compound has a phenol structure, using one or more compounds selected from the group consisting of phosphonic acid compounds and phosphinic acid compounds that have a phenol moiety within the same molecule is preferable as it significantly improves catalytic activity. Among these, using phosphonic acid compounds having one or more phenol moieties within the same molecule is particularly preferable as it significantly improves catalytic activity.

[0023] Furthermore, examples of phosphorus compounds having a phenol portion within the same molecule include compounds represented by the following general formulas (Chemical Formula 1) and (Chemical Formula 2).

[0024] [ka]

[0025] [ka]

[0026] (In formulas (Chemical Formula 1) to (Chemical Formula 2), R1 represents a hydrocarbon group having 1 to 50 carbon atoms including a phenol moiety, a substituent such as a hydroxyl group, a halogen group, an alkoxyl group, or an amino group, and a hydrocarbon group having 1 to 50 carbon atoms including a phenol moiety. R4 represents a hydrocarbon group having 1 to 50 carbon atoms including hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, a substituent such as a hydroxyl group, a halogen group, an alkoxyl group, or an amino group. R2 and R3 each independently represent a hydrocarbon group having 1 to 50 carbon atoms including hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, a substituent such as a hydroxyl group, or an alkoxyl group. However, the hydrocarbon group may include branched structures, alicyclic structures such as cyclohexyl, or aromatic ring structures such as phenyl or naphthyl. The ends of R2 and R4 may be bonded together.)

[0027] Examples of phosphorus compounds having a phenol portion within the same molecule include p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonic acid, diethyl p-hydroxyphenylphosphonic acid, diphenyl p-hydroxyphenylphosphonic acid, bis(p-hydroxyphenyl)phosphinate, methyl bis(p-hydroxyphenyl)phosphinate, phenyl bis(p-hydroxyphenyl)phosphinate, p-hydroxyphenylphenylphosphinate, methyl p-hydroxyphenylphenylphosphinate, phenyl p-hydroxyphenylphenylphosphinate, p-hydroxyphenylphosphinate, methyl p-hydroxyphenylphosphinate, and phenyl p-hydroxyphenylphosphinate. Other examples of phosphorus compounds represented by the following general formula (Chemical Formula 3) can be listed.

[0028] [ka]

[0029] In formula (Chemical Formula 3), X1 and X2 represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or a metal with a valency of 1 or more, respectively. Furthermore, X1 may be a metal with a valency of 2 or more, and X2 may not be present. In addition, an anion corresponding to the excess valency of the metal may be present in the phosphorus compound. Li, Na, K, Ca, Mg, and Al are preferred metals.

[0030] By adding these phosphorus compounds, which have a phenol moiety within the same molecule, during the polymerization of polyester, the catalytic activity of the aluminum compound is improved, and the thermal stability of the polymerized polyester resin is also enhanced.

[0031] Among the above, the phosphorus compound preferred for use as a polycondensation catalyst is at least one phosphorus compound selected from the compounds represented by chemical formulas (Chemical Formula 4) and (Chemical Formula 5).

[0032] [ka]

[0033] [ka]

[0034] The compound represented by the above chemical formula (Chemical Formula 4) is commercially available as lrganox1222 (manufactured by BASF Co., Ltd.). Additionally, the compound represented by the chemical formula (Chemical Formula 5) is commercially available and usable as lrganox1425 (manufactured by BASF Co., Ltd.).

[0035] The amount of phosphorus compound used in the polymerization catalyst for the polyester resin used in the biaxially oriented polyester film of the present invention is preferably such that 10 to 100 ppm of phosphorus atoms remain relative to the total mass of the raw material polyester resin, more preferably 15 to 90 ppm, even more preferably 20 to 80 ppm, particularly preferably 25 to 70 ppm, and most preferably 30 to 60 ppm. If the amount of phosphorus atoms remaining exceeds the upper and lower limits mentioned above, it may reduce polymerization activity. When phosphorus compounds are subjected to reduced pressure during polyester polymerization, approximately 10-30% of the amount used is removed from the system, depending on the conditions. Therefore, in practice, it is necessary to conduct several trial experiments to determine the residual rate of phosphorus compounds in the polyester before deciding on the amount to use.

[0036] Furthermore, using the above-mentioned phosphorus compounds can improve the heat resistance of the resin. Although the exact reason is unclear, it is thought that the hindertophenol portion in the phosphorus compounds improves the heat resistance of the polyester resin.

[0037] If the residual amount of phosphorus compounds falls below 10 ppm, the above-mentioned effect of improving heat resistance diminishes, and as a result, the heat resistance and color improvement effects of the polyester resin used in the biaxially oriented polyester film of the present invention may not be observed.

[0038] To further improve catalytic activity without impairing the effects of the present invention, metal-containing polycondensation catalysts such as antimony compounds, titanium compounds, tin compounds, and germanium compounds may be used in combination. In this case, the antimony compound is preferably present in an amount of 10 ppm or less of antimony atoms relative to the mass of the resulting copolymerized polyester resin, the germanium compound is preferably present in an amount of 10 ppm or less of germanium atoms relative to the mass of the resulting copolymerized polyester resin, the titanium compound is preferably present in an amount of 3 ppm or less of titanium atoms relative to the mass of the resulting copolymerized polyester resin, and the tin compound is preferably present in an amount of 3 ppm or less of tin atoms relative to the mass of the resulting polyester resin. For the purposes of this invention, it is preferable to avoid using metal-containing polycondensation catalysts such as antimony compounds, titanium compounds, tin compounds, and germanium compounds as much as possible.

[0039] In the polyester resin used in the biaxially oriented polyester film of the present invention, in addition to the aluminum compound, at least one selected from alkali metals, alkaline earth metals, and their compounds may be coexisted as a second metal-containing component. Coexisting such a second metal-containing component in the catalyst system has the effect of suppressing the formation of diethylene glycol, as well as increasing catalytic activity, thereby obtaining a catalyst component with a higher reaction rate, which is effective in improving productivity. When alkali metals, alkaline earth metals, or their compounds are added in combination, the amount used (mol%) is preferably 1 x 10⁻⁶ relative to the number of moles of dicarboxylic acid components constituting the polyester resin. -5 The concentration is approximately 0.01 mol%. Alkali metals, alkaline earth metals, or their compounds remain almost 100% of the amount used even when subjected to a reduced pressure environment during polyester polymerization, so the amount used can be considered to be the amount remaining.

[0040] The polymerization catalyst for the polyester resin used in the biaxially oriented polyester film of the present invention has catalytic activity not only in polycondensation reactions but also in esterification and transesterification reactions. Transesterification reactions between alkyl esters of dicarboxylic acids such as dimethyl terephthalate and glycols such as ethylene glycol are usually carried out in the presence of a transesterification catalyst such as zinc, but the catalyst of the present invention can be used instead of these catalysts. Furthermore, the polymerization catalyst according to the present invention has catalytic activity not only in melt polymerization but also in solid-phase polymerization and solution polymerization.

[0041] The polymerization catalyst for the polyester resin used in the biaxially oriented polyester film of the present invention can be added to the reaction system at any stage of the polymerization reaction. For example, it can be added to the reaction system before the start of the esterification reaction or transesterification reaction, at any stage during the reaction, immediately before the start of the polycondensation reaction, or at any stage during the polycondensation reaction. In particular, it is preferable to add the aluminum compound and phosphorus compound according to the present invention immediately before the start of the polycondensation reaction.

[0042] In the process of manufacturing the polyester of the present invention, or in the manufactured polyester, various additives may be added within the range where its properties are not impaired. For example, plasticizers, ultraviolet stabilizers, anti-coloring agents, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, yarn friction reducers, mold release agents, antioxidants, ion exchangers, coloring pigments, etc. can be added. These additives are added in the range of 5 to 50% by mass based on the entire polyester resin composition.

[0043] Also, in these polyester resins, other components may be copolymerized as long as the object of the present invention is not impaired. Specifically, as the copolymerization component, in the dicarboxylic acid component, isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid and its ester-forming derivatives, etc. can be mentioned. Also, as the diol component, diethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol can be mentioned. Also, polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol can be mentioned. The copolymerization amount is preferably within 10 mol% per repeating unit constituting, more preferably within 5 mol%, and most preferably 3 mol% or less.

[0044] The intrinsic viscosity of the polyester resin constituting the biaxially oriented polyester film of the present invention is preferably in the range of 0.50 to 0.90 dl / g, more preferably in the range of 0.55 to 0.80 dl / g from the viewpoints of film-forming property and recyclability.

[0045] In the polyester resin composition of the present invention, in order for at least one surface of the biaxially oriented polyester film of the present invention to satisfy all of the following requirements (1) to (4), it is preferable to contain at least one kind of particles selected from the group consisting of inorganic particles, organic particles, and particles composed of a mixture thereof. (1) The number of fine protrusions with a height of less than 3 nm per area of 4×10 -12 m 2 is 250 or more. (2) Area 4×10 -12m 2 The number of microscopic protrusions with a height of 3 nm or more per unit area is between 300 and 600. (3) The arithmetic mean height Sa is between 0.010 μm and 0.025 μm. (4) The contact angle of diiodomethane is 23° or greater.

[0046] (1) Area 4X10 -12 m 2 Number of micro-protrusions less than 3 nm per unit Because biaxially oriented polyester film has electrical insulating properties, static marks, which are areas that become partially charged due to contact with conveyor rolls or peeling during the film manufacturing and processing stages, and static mark discharge marks caused by the discharge of accumulated static electricity, are prone to occur. -12 m 2 When the number of microscopic protrusions less than 3 nm in height per layer exceeds 250, static marks and static mark discharge traces are reduced, improving the gas barrier performance of the inorganic thin film layer. The reason is, area 4x10 -12 m 2 If the number of microscopic protrusions less than 3 nm in height per surface is 250 or more, then even when the film and metal roll come into contact with strong force during the processes of transporting and unwinding the manufactured film, and the high protrusions on the film surface are pressed into the metal roll, the contact area between the film surface and the metal roll becomes extremely small. As a result, the amount of static charge due to friction is reduced, and consequently, static marks and static mark discharge marks are reduced. More preferably, there are 300 or more, more preferably 400 or more, and particularly preferably 500 or more. This tendency also applies to friction caused by contact between films. The number of fine protrusions less than 3 nm in height improves the slipperiness of the film, reduces blocking properties, and has the advantage of not negatively affecting the gas barrier properties of the inorganic thin film layer formed on the film surface. Furthermore, even within the range where the number of micro-protrusions less than 3 nm in height is 600 or less, static marks and static mark discharge traces are sufficiently few. If the number of defects becomes too high, the number of defects in the inorganic thin film increases, reducing its barrier function.

[0047] (2) Area 4X10 -12 m 2 Number of micro-protrusions with a height of 3 nm or more per unit area A number of microscopic protrusions with a height of 3 nm or more of 300 or more is preferable because it reduces the coefficient of dynamic friction between films, and because biaxially oriented polyester films have electrical insulating properties, it is less likely to generate static marks, which are partially charged areas caused by contact with conveyor rolls or peeling during the film manufacturing and processing processes, as well as static mark discharge marks caused by the discharge of accumulated static electricity. A more preferable number is 400 or more, and more preferably 500 or more. If the number of micro-protrusions with a height of 3 nm or more is 600 or less, the number of defects in the inorganic thin film layer will not become too high, and sufficient gas barrier properties can be obtained.

[0048] (3) Arithmetic mean height Sa The arithmetic mean height Sa of at least one face of the biaxially oriented polyester film of the present invention is preferably 0.010 or more and 0.025 μm or less. A film with an arithmetic mean height Sa of 0.010 μm or more is preferable because it reduces the likelihood of adhesion (blocking phenomenon) between films within the film roll in the recesses between protrusions formed on the film surface and between protrusions formed on the film surface, allowing for smooth secondary processing of the film. More preferably, it is 0.013 μm or more, and more preferably 0.015 μm or more. An arithmetic mean height Sa of 0.025 μm or less is preferable because it reduces the haze of the biaxially oriented polyester film, particularly the external haze, resulting in excellent transparency. More preferably, it is 0.023 μm or less, more preferably 0.020 μm or less, and particularly preferably 0.017 μm or less. The arithmetic mean of the other film surface, Sa, is preferably within a similar range.

[0049] Examples of inorganic particles that can be used include those made of silica (silicon oxide), alumina (aluminum oxide), titanium dioxide, calcium carbonate, kaolin, and barium sulfate. Examples of organic particles include acrylic resin particles, melamine resin particles, silicone resin particles, and particles made of cross-linked polystyrene. In particular, particles made of silica (silicon oxide), calcium carbonate, or alumina (aluminum oxide), or particles made of polymethacrylate, polymethyl acrylate, or derivatives thereof are preferred, particles made of silica (silicon oxide) or calcium carbonate are more preferred, and inorganic particles made of silica (silicon oxide) are especially preferred.

[0050] In the present invention, it is preferable that the particle size distribution of the particles used is monodisperse. The shape of inorganic nanoparticles is not particularly limited, but the closer they are to a spherical shape, the more the number of micro-protrusions less than 3 nm in height can be increased without significantly changing the number of micro-protrusions greater than 3 nm in height or the arithmetic mean height Sa.

[0051] In this invention, the weight-average particle size measured by a Coulter counter is preferably in the range of 0.8 to 1.8 μm. If the weight-average particle size of the particles is 0.8 μm or larger, the number of fine protrusions less than 3 nm in height and the arithmetic mean height Sa tend to be above the lower limits of (1) and (3) above, respectively. When the weight-average particle size of the particles is 1.8 μm or less, it is easier to keep the arithmetic mean height Sa below the upper limit of (3) above, and it is also suitable for keeping the number of fine protrusions with a height of less than 3 nm above the lower limit of (1) above.

[0052] In the present invention, the concentration of inorganic particles in the polyester resin composition (masterbatch) containing particles is preferably 7,000 to 100,000 ppm, more preferably 8,000 to 80,000 ppm, and particularly preferably 9,000 to 50,000 ppm. When the concentration of inorganic particles in the masterbatch is less than 7,000 ppm, the addition ratio of the masterbatch containing inorganic particles increases, which is preferable in terms of manufacturing costs. When the concentration of inorganic particles in the masterbatch is greater than 100,000 ppm, the variation in the raw material ratio in the longitudinal direction becomes large due to segregation of the raw materials, which tends to increase the longitudinal variation of the obtained film.

[0053] In the present invention, the particles can be incorporated into the polyester resin composition at any of the following stages: for example, during the esterification stage for the production of the polyester resin, after the completion of the transesterification reaction, or before the start of the polycondensation reaction. However, it is preferable to add the particles as a slurry dispersed in ethylene glycol or the like to promote the polycondensation reaction. Alternatively, the process may be carried out by blending a slurry of particles dispersed in ethylene glycol or water with a polyester resin raw material using a vented kneading extruder, or by blending dried particles with a polyester resin raw material using a kneading extruder.

[0054] In the process of mixing particles with polyester resin raw materials, it is preferable to minimize particle aggregates in order to stably obtain the desired surface state. However, this influence can be reduced by adjusting the conditions of the film-forming process for the biaxially oriented polyester film that follows the mixing process.

[0055] Furthermore, the polyester resin composition in the present invention may contain small amounts of other polymers, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, plasticizers, pigments, or other additives, to the extent that it does not impair the objectives of the present invention.

[0056] Method for manufacturing biaxially oriented polyester film The biaxially oriented polyester film of the present invention can be obtained, for example, by supplying and mixing polyester resin chips that do not use an antimony compound as a polymerization catalyst and polyester resin chips that do not use an antimony compound as a polymerization catalyst containing particles to an extruder equipped in a hopper, melt-extruding the mixture with the extruder to form an unstretched sheet, and then stretching the unstretched sheet. The following are some suitable examples, but are not limited to these.

[0057] The film of the present invention may have a single-layer structure of at least one layer, or a laminated structure of two or more layers. It may have two, three, four, or five layers. In the case of two layers, it is a laminated section / base layer, and in the case of three layers, it is a laminated section (A) / base layer / laminated section (B). In the case of three layers, laminated section (A) and laminated section (B) may have the same composition and configuration, or they may have different compositions, for example, a particle-free layer / base layer / particle-containing layer. They may also have substantially the same thickness or different thicknesses. Preferably, it is desirable for laminated section (A) and laminated section (B) to be designed with the same composition, as this facilitates production.

[0058] Next, it is preferable that at least one layer of each of the above-mentioned layers constituting the film of the present invention is oriented biaxially. It is particularly preferable that all layers of the laminated structure of two or more layers are oriented biaxially. At least the surfaces on which the inorganic oxide layers are stacked are oriented biaxially.

[0059] The lower limit of the particle content in the laminated portion of the biaxially oriented polyester film of the present invention is 1000 ppm by weight, more preferably 1300 ppm by weight, and particularly preferably 1400 ppm by weight. When the particle content is 1000 ppm by weight or more, it is easier to keep the number of fine protrusions with a height of less than 3 nm and the number of fine protrusions with a height of 3 nm or more above the lower limits of (1) and (2) above, respectively. The upper limit of the particle content is preferably 3000 ppm by weight, more preferably 2500 ppm by weight, even more preferably 2200 ppm by weight, and particularly preferably 1800 ppm by weight.

[0060] When mixing the resin chips that will be used as raw materials, it is preferable to supply polyester resin chips that do not use antimony compounds as polymerization catalysts from above into the hopper, and to supply polyester resin chips that do not use antimony compounds as polymerization catalysts and contain particles through a pipe (hereinafter sometimes referred to as an inner pipe) that is inside the hopper and has an outlet directly above the extruder, mix the two types of chips, and then melt-extrude them. If polyester resin chips that do not use antimony compounds as polymerization catalysts and polyester resin chips that do not use antimony compounds as polymerization catalysts and contain particles are mixed and placed in the hopper above the extruder, there is a possibility that the resin chips with different specific gravities and chip shapes will cause raw material segregation inside the hopper, and there is a particularly high concern that raw material segregation will occur in parts of the hopper where the inner wall is not vertical (slanted parts). However, if the polyester resin composition is supplied directly to the part of the hopper directly above the extruder inside the hopper through the inner pipe, raw material segregation can be reduced even if the specific gravities and chip shapes differ, and polyester film can be stably industrially produced.

[0061] When melt-extruding a polyester resin composition containing a polyester resin that does not use an antimony compound as a polymerization catalyst and a polyester resin containing particles that does not use an antimony compound as a polymerization catalyst, it is preferable to dry it using a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer. After drying the polyester resin composition containing a polyester resin that does not use an antimony compound as a polymerization catalyst and a polyester resin containing particles that does not use an antimony compound as a polymerization catalyst, it is melted at a temperature above the melting point of the polyester resin and between 200 and 300°C and extruded into a film. Alternatively, the polyester resin, particles, and additives as needed may be fed in separate extruders, combined, mixed, melted, and extruded into a sheet. When extruding the molten resin composition, any existing method such as the die method or the tubular method can be used.

[0062] Then, by rapidly cooling the sheet-like molten polyester resin after extrusion, an unstretched sheet can be obtained. As a method for rapidly cooling the molten polyester resin, a method of casting the molten polyester resin from a die onto a rotating drum and rapidly cooling and solidifying it to obtain a substantially unoriented resin sheet can be suitably employed. The temperature of the rotating drum is preferably set to 40°C or lower.

[0063] Furthermore, by combining processes such as stretching in the longitudinal and width directions, heat setting, and heat relaxation, the obtained unstretched sheet can be used to obtain the biaxially oriented polyester film of the present invention. The details are explained below. The longitudinal direction refers to the direction in which the unstretched sheet is run, and the width direction refers to the direction perpendicular to that.

[0064] The stretching method can be either simultaneous biaxial stretching, where stretching is performed in both the longitudinal and width directions at the same time, or sequential biaxial stretching, where stretching in either the longitudinal or width direction is performed first. However, sequential biaxial stretching is the most preferable method because it offers a fast film formation speed, high productivity, and superior thickness uniformity in the resulting biaxially oriented polyester film. The film formation speed referred to here means the running speed (m / min) of the biaxially oriented polyester film as it is wound onto the master roll after the stretching process.

[0065] The temperature during longitudinal stretching of the unstretched sheet is preferably in the range of (Tg+15) to (Tg+55)°C, using the glass transition temperature (Tg) of the polyester resin as an indicator, and the stretching ratio is preferably in the range of 4.2 to 4.7 times. When the stretching temperature is (Tg + 55)°C or lower, and the stretching ratio is 4.2 times or more, it is easier to keep the number of fine protrusions with a height of less than 3 nm above the lower limit of (1) above, and the balance of molecular orientation in the longitudinal and width directions is good, and the difference in physical properties between the longitudinal and width directions is small, which is preferable. In addition, the planarity of the resulting biaxially oriented polyester film is also good, which is preferable. On the other hand, when the stretching temperature in the longitudinal direction is (Tg+15)°C or higher, and the stretching ratio is 4.7 times or less, it is easier to keep the arithmetic mean height Sa below the upper limit of (3) above. This is preferable because the tensile stress (boeing phenomenon) generated in the opposite direction to the film's running direction during the thermal relaxation process does not become too large.

[0066] Furthermore, in longitudinal stretching, a method that divides the stretching into two, three, or four or more stages between multiple rolls, rather than a single stage, is preferable because it allows for a larger stretching ratio in the longitudinal direction without significantly increasing the stretching speed, thereby further reducing the difference in physical properties in the film width direction. From the standpoint of effectiveness, equipment, and cost, two-stage or three-stage stretching is preferable.

[0067] When stretching a film obtained by stretching an unstretched sheet in the longitudinal direction in the width direction, the film is guided to a tenter device, and both ends of the film, which has been stretched in the longitudinal direction from an unstretched sheet, are gripped with clips. After heating the film to a predetermined temperature with hot air, the film can be stretched in the width direction by increasing the distance between the clips while conveying it in the longitudinal direction. When the temperature during stretching in the width direction is Tg + 5°C or higher, it is easier to keep the arithmetic mean height Sa below the upper limit of (3) above, and breakage during stretching becomes less likely, which is preferable. Furthermore, when the stretching temperature is Tg + 40°C or lower, it is easier to keep the number of fine protrusions with a height of less than 3 nm above the lower limit of (1) above, and uniform stretching in the width direction becomes easier, and thickness variations in the width direction are less likely to become large, which is preferable as it reduces the variation in the width direction of the winding hardness of the roll film surface. More preferably, the temperature is between Tg+8°C and Tg+37°C, and even more preferably between Tg+11°C and Tg+34°C. The preferred stretching ratio in the width direction of the film obtained by stretching the unstretched sheet in the longitudinal direction is 4.0 times or more and 6.0 times or less. A widthwise stretching ratio of 4.0 times or more is preferable because it makes it easier to keep the number of fine protrusions with a height of less than 3 nm above the lower limit of (1) above, and also makes it easier to obtain a high yield in terms of material balance, and does not reduce mechanical strength, and thickness variations in the widthwise direction do not become large, and variations in winding hardness in the widthwise direction of the roll film do not occur. A widthwise stretching ratio of 4.1 times or more is more preferable, and 4.2 times or more is even more preferable. Furthermore, a widthwise stretching ratio of 6 times or less is preferable because it makes it easier to keep the arithmetic mean height Sa below the upper limit of (3) above, and also makes it less likely to break during stretching and film formation.

[0068] A heat-setting process is performed following the stretching process in the width direction. The heat-setting temperature of the film obtained by stretching an unstretched sheet in the longitudinal direction and then stretching the film in the width direction is preferably 240°C to 250°C. When the thermal fixing temperature is 240°C or higher, it is easier to keep the number of fine protrusions with a height of less than 3 nm above the lower limit of (1) above, and the thermal shrinkage rate does not become too high in both the longitudinal and width directions, which is preferable because it improves the thermal dimensional stability during vapor deposition. On the other hand, when the heat fixation temperature is 250°C or lower, the increase in saturation is less likely to occur, which is preferable.

[0069] Furthermore, a heat relaxation treatment process is performed, which may be performed separately from the heat fixing process or simultaneously with the heat fixing process. The relaxation rate in the film width direction during the heat relaxation treatment process is preferably 4% to 8%. A relaxation rate of 4% or higher is preferable because it prevents the resulting biaxially oriented polyester film from becoming excessively high in the width direction, thus improving dimensional stability during vapor deposition. On the other hand, when the slack rate is 8% or less, the tensile stress (boeing phenomenon) generated in the opposite direction to the film's running direction in the center of the film's width direction does not become too large, and the film thickness fluctuation rate in the width direction does not become large, which is preferable.

[0070] In the heat relaxation process, the film obtained by stretching the unstretched sheet longitudinally is subject to significant vertical fluctuations. As the film stretched in the width direction shrinks due to heat relaxation, the constraint force in the width direction decreases, causing it to sag under its own weight. Additionally, the film may bulge due to the accompanying airflow of hot air blown from nozzles installed above and below the film. Consequently, the resulting biaxially oriented polyester film is prone to large fluctuations in orientation angle and the difference in oblique heat shrinkage rates. One way to mitigate these issues is to adjust the airflow speed of the hot air blown from the upper and lower nozzles to keep the film parallel.

[0071] In the biaxially oriented polyester film for vapor deposition of the present invention, it is preferable to adjust the surface contact angle by corona discharge treatment. The corona treatment can be adjusted by the shape and number of electrodes used for corona discharge, the distance between the electrodes and the film, the discharge current, the film formation speed, the material of the roll on the back of the film, and so on. It is preferable to remove static electricity after corona treatment to eliminate any charged electrons. If the material is still charged and wound using a winder to produce a master roll, the master roll may have a loose winding, or discharge or adsorption may occur when unwinding in the next process, which is undesirable. It is preferable to corona-treat the surface of a biaxially oriented polyester film obtained by stretching a polyester resin polymerized using an aluminum catalyst to achieve a diiodomethane contact angle of 23° or higher. More preferably, it is 24° or higher, and more preferably, 26° or higher. Increasing the contact angle above 27° requires stronger corona treatment, which affects other physical properties of the film; therefore, a contact angle of 27° or less is preferable.

[0072] It is preferable that the contact angle be maintained at 23° or higher after film formation. If the contact angle drops below 23° when inorganic oxide is formed on the film roll, the quality of the inorganic oxide film will decrease, and the barrier properties will be reduced. Methods to maintain a temperature above 23°C include increasing the temperature during film formation, storing roll films at a lower temperature, and using an aluminum catalyst instead of a polyester polymerization catalyst. While it is preferable for film rolls to proceed to the vapor deposition process immediately after production, it is preferable for the contact angle to be maintained at 23° or higher for at least 200 days to allow for flexible operation depending on the production capacity of the vapor deposition equipment and market conditions. Maintaining this for 300 days or more is preferable for even more flexible operation, but attempting to maintain it for 450 days or more will affect other physical properties, so 450 days or less is preferable.

[0073] The wide, biaxially oriented polyester film stretched and formed using the method described above is wound up by a winder device to produce a master roll. The width of the master roll is preferably between 5,000 mm and 10,000 mm. A roll width of 5,000 mm or more is preferable because it lowers the cost per unit area of ​​the film during the subsequent slitting process. The length of the master roll is preferably between 10,000m and 100,000m. A roll length of 5,000m or more is preferable because it lowers the cost per film area during the subsequent slitting process. Furthermore, the width of the roll film slit from the master roll is preferably between 1,500mm and 4,000mm. A width of 1,500mm or less results in inefficient and costly vapor deposition processes. Conversely, a width of 4,000mm or more is undesirable because it requires larger vapor deposition equipment, increasing costs. The roll length of the film is preferably between 10,000m and 140,000m. If the roll length is less than 10,000m, the area that can be processed in a single deposition is small, resulting in higher deposition costs. If the roll length exceeds 14,000m, even with a thickness of 12μm, the roll diameter exceeds 1500mm, which is undesirable because it increases the size of the deposition equipment. Also, even with a width of 2000mm, the weight becomes about 5t, which reduces handling efficiency. Preferably, the width is 1500 mm or more and 2500 mm or less. A roll length of 50,000 m to 80,000 m is preferable considering cost and handling.

[0074] The film thickness of the biaxially oriented polyester film is preferably 5 to 40 μm. A thickness of 5 μm or more is preferable because it does not reduce the strength or stiffness of the film, and it is less likely to wrinkle when wound in a vacuum device. On the other hand, a film thickness of 40 μm or less is preferable from a cost standpoint as it provides sufficient strength and stiffness. A film thickness of 8 to 30 μm is more preferable, and 9 μm to 20 μm is particularly preferable.

[0075] To obtain a winding width and length suitable for the deposition apparatus from the master roll, a core suitable for the deposition machine is used in the slitting process. However, if corona treatment is not performed in the film formation process, it is preferable to perform corona treatment in the slitting process to adjust the surface contact angle. Even if corona treatment is not performed, static electricity will be generated in the slitting process, so it is preferable to discharge the static electricity when winding onto the core.

[0076] When winding onto the core, it is preferable to adjust the winding tension and the contact pressure of the contact roll (1) shown in Figure 1 so that the winding hardness of the roll film is adjusted so that the R value is 25 or less and 15 or more when using a rebanding hammer. When the winding hardness exceeds 25, even with optimized surface protrusions, the films adhere strongly to each other. When laminating inorganic thin films in a vapor deposition apparatus (Figure 2), the peeling charge increases when unwinding the film in a vacuum, creating defects in the inorganic oxide layer. When the hardness falls below 15, the amount of air between the wound films increases. When the roll film is set in the vapor deposition apparatus for the deposition of the inorganic oxide layer and the air is exhausted, the air between the films escapes, causing the film to slide sideways with the air, resulting in a bamboo shoot-like shape in the roll film, making deposition impossible.

[0077] The present invention is a transparent gas barrier film characterized by having an inorganic oxide laminated onto the biaxially oriented polyester film prepared as described above.

[0078] A suitable method for laminating inorganic oxides onto the aforementioned biaxially oriented polyester roll film is a dry process utilizing a vacuum. Among these, the vapor deposition method is particularly suitable. The vapor deposition method allows for the lamination of inorganic oxides over a large area at high speed. Any of the following deposition methods can be used: resistance heating, in which the deposition material is evaporated in a resistance heating boat; induction heating, in which the deposition material is placed in a carbon crucible and heated by applying a high-frequency electromagnetic field; or electron beam heating, in which the deposition material is heated by an electron gun.

[0079] Figure 2 shows a schematic diagram of an electron beam heating type deposition apparatus. The process of layering inorganic oxides is explained, but the invention is not limited to this. The biaxially oriented polyester roll film is prepared on the unwinding roll (3) of the vapor deposition apparatus. The biaxially oriented polyester film (4) is unwound from the unwinding roll (3) and the biaxially oriented polyester vapor-deposited surface is treated by a plasma treatment device (5). The plasma treatment device (5) has electrodes and is designed to allow gas to be introduced between the electrodes and the biaxially oriented polyester film (4). A DC or AC voltage is applied to the electrodes to cause a discharge and generate plasma. This plasma is used to treat the vapor-deposited surface of the biaxially oriented polyester film. The purpose of plasma treatment is to remove moisture and other contaminants that adhere to the biaxially oriented polyester film when it is stored in the atmosphere. For this purpose, a noble gas such as argon is preferred as the gas to be introduced. Among noble gases, argon gas is particularly preferred from a cost perspective.

[0080] The biaxially oriented polyester film (4) that has passed through the plasma treatment device (5) is moved to a coating roll (6) cooled to -20°C. The electron beam (8) irradiated from the electron gun (7) heats the deposition material (9) in the crucible, causing the material to evaporate and inorganic oxides to be deposited on the corona-treated surface of the biaxially oriented polyester film (4). Before the transparent gas barrier film, which has an inorganic oxide laminated onto the corona-treated surface of a biaxially oriented polyester film (4), leaves the coating roll (6), an electrostatic eliminator (10) removes any electrons charged on the surface of the transparent gas barrier film. The transparent gas barrier film leaves the coating roll (6) and is wound onto a winding roll (13), but before that, the thickness of the laminated inorganic oxide, or the thickness and composition, is measured using an optical thickness gauge (11), an X-ray fluorescence thickness gauge (12), or both. The measured values ​​are fed back to the electron gun (7) to adjust the intensity and scanning of the electron beam (8) to achieve the target thickness or thickness and composition.

[0081] The inorganic oxide in the transparent barrier film of this invention is preferably between 5 nm and 30 nm in thickness. If it is too thin, it will not be uniform and the barrier properties cannot be maintained. If it is too thick, the inorganic oxide will crack when the transparent barrier film is deformed, and the barrier properties will decrease.

[0082] As described above, aluminum oxide, silicon oxide, and mixtures thereof are suitable inorganic oxides for the transparent barrier film of this invention. Mixtures of aluminum oxide and silicon oxide are particularly suitable. In particular, in the mixture of aluminum oxide and silicon oxide, an aluminum oxide content of 20 to 60% by weight is preferred. If the aluminum oxide content is too low, the barrier properties will decrease. If it is too high, the inorganic oxide will harden, and when the transparent barrier film of this invention is deformed, the inorganic oxide will crack, reducing the barrier properties.

[0083] In this invention, the winding hardness of the roll film is the value obtained by measuring the hardness of the roll film with a rebound hammer (generally a Schmidt hammer). A rebound hammer is originally a device for evaluating the compressive failure strength of concrete. In concrete, there is a correlation between compressive failure strength and surface hardness, so it is used as a device for measuring surface hardness. A rod is launched using a spring or the like and hits the object to be measured. The impact strength of the rod that bounces back is measured and quantified. The value is called the R value.

[0084] The number of microprojections refers to the number described below. A 10mm x 10mm area was cut from a biaxially oriented polyester film and scanned using a scanning probe microscope in phase mode to obtain an area of ​​4 x 10 -12 m 2 This is the number of particles (protrusions) larger than 3 nm and smaller than 3 nm counted from an image obtained by scanning within a 2 μm x 2 μm area.

[0085] In this application, the arithmetic mean height Sa refers to the value specified in ISO 25178.

[0086] In this invention, diiodomethane refers to diiodomethane that is classified as a special grade reagent with a purity of 99% or higher. In this invention, the contact angle is the interior angle (θ) formed between the tangent (16) to the surface of a droplet (15) placed on the biaxially oriented polyester film (14) and the surface of the biaxially oriented polyester film (14), as explained in Figure 3.

[0087] In this invention, the transmittance is a value measured in accordance with JIS K7126-1. In this invention, the test gas is a dry elemental gas with a purity of 99.5% or higher, and the high-pressure side pressure is standard atmospheric pressure (101325 Pa), and the temperature is 23°C.

[0088] In a laminated film in which an inorganic thin film layer is formed on a film, if we consider the case where gas moves from the substrate film side to the inorganic thin film layer side, the permeating gas moves through the free volume of the substrate film and reaches the inorganic thin film layer by diffusion. In the inorganic thin film layer, there are two possible scenarios: the gas passing through large defects such as cracks and pinholes, and the gas permeating through structural defects within the inorganic thin layer. The structural defects were small, at the level of noble gas atoms, and we found that there was a difference in permeability between the relatively large argon and the small helium. Argon gas can barely penetrate structural defects in inorganic thin film layers, but it can penetrate larger defects such as cracks. Therefore, taking the ratio (PtAr / PfAr) of the transmittance of the argon gas substrate film to the transmittance of the transparent vapor-deposited film with the inorganic thin film layer laid on top of it represents the extent to which the area of ​​defects due to cracks, etc., in the inorganic thin film layer is equal to the area of ​​the inorganic thin film layer if there were no defects, i.e., the film surface area. In contrast, helium gas can penetrate not only large defects such as cracks in the inorganic thin film layer, but also structural defects in the inorganic thin film layer. Therefore, the fewer structural defects there are in the inorganic thin film layer, the more helium gas permeation will occur through defects such as cracks in the inorganic thin film layer. The ratio of helium gas permeability through the substrate film to that of the transparent barrier film with the inorganic thin film layer (PtHe / PfHe) will be approximately the same as the ratio of argon gas permeability through the substrate film to that of the transparent barrier film with the inorganic thin film layer (PtAr / PfAr). In other words, the value of (PtHe / PfHe) / (PtAr / PfAr) is 1. Preferably, a value smaller than 1.5 is preferable, as it indicates fewer defects, but defects are more likely to occur when forming films at high speed using vapor deposition. Compared to defects such as cracks, a value of 2 or less allows for low water vapor permeability. The present invention allows for the quantification of the fact that the inorganic thin film layer of the transparent barrier film has few structural defects and the film is dense. [Examples]

[0089] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The film properties obtained in each example were measured and evaluated using the following method.

[0090] hardness Using a Schmidt hammer L-type manufactured by Proceq (Switzerland), the R value was measured at 400mm intervals in the width direction of the film on the surface of the film roll, and the average value was defined as the hardness.

[0091] Number of fine protrusions A section of biaxially oriented polyester film was cut to an area of ​​10 mm in the longitudinal direction and 10 mm in the width direction. Measurements were taken using a Shimadzu scanning probe microscope (SPM-9700) under the following observation conditions, and images of the measurement surface were captured. The obtained images (height traces) were processed under the following conditions. Using the particle analysis software of the SPM-9700 series, the number of particles larger than 3 nm (number of protrusions) and the number of particles smaller than 3 nm (number of protrusions) were analyzed under the following particle analysis conditions, with a threshold of 3 nm. The area was then measured in 4 x 10⁻⁶ squared. -12 m 2 The count was performed within a 2μm x 2μm area. For particles smaller than 3nm (number of protrusions), only those 0.01nm or larger were counted. Measurements were taken five times at different locations, and the average of the three measurements (excluding the highest and lowest counts) was calculated to determine the number of micro-protrusions. (Observation conditions) Cantilever: Made of Si (silicon) Scanning mode: Phase mode Scanning speed: 2Hz Scanning range: 2 μm Pixel count: 256x256 Offset X: 0 μm Offset Y: 0 μm Scanning angle: 0° Operating point: Around 0.1V (optimal tuning value) P-gain: 0.001 Gain: 1500 Offset Z: 0 μm Z Range: X2 Scanning mode: constant (Image processing) Tilt correction: Average value in the X direction (X), average value in the Y direction (Y), line fit (L) Noise line removal: Mode (range selection), Auto selection (particle analysis) Target shape: Particle XY threshold: relative value 30% Number of pixels to ignore: 5

[0092] Arithmetic mean height Sa, maximum height Sz A 10cm x 10cm area was cut from the obtained film, and a Zygo white laser interferometer (NEWVIEW8300) was used. A 10x lens was attached to the interferometer, and scanning was performed to measure the arithmetic mean height (μm) and maximum height (μm). With the zoom setting set to ×2, measurements were taken within a range of 0.44 μm in the MD direction and 0.44 μm in the width direction of one surface, targeting the surface excluding unmelted material and foreign matter such as dust. Measurements were taken at five arbitrary points on the 10cm x 10cm sample, and the average value was defined as the arithmetic mean height Sa.

[0093] contact angle The contact angle of diiodomethane as used in this invention was measured by the following method. Measurements were taken in a room adjusted to a temperature of 23°C and humidity of 50%. The measuring instrument used was a KRUESS DROP SHAPE ANALYER-DSA100. The diiodomethane used was top-grade diiodomethane from Nacalai Tesque Co., Ltd. A 0.8 μl droplet of diiodomethane was prepared using a 0.5 mm diameter PTFE needle and dropped onto the surface of a biaxially oriented polyester film. After 1 second, an image of the droplet was captured, and the contact angle was determined using the θ / 2 method (width-to-height method). Ten measurements were taken, and the average value was taken as the contact angle of the sample.

[0094] Gas permeability Gas permeability was measured using the K-315N-01 gas permeability measuring device manufactured by Tsukuba Rika Seiki Co., Ltd. The area used for measuring transmittance was a circle with a diameter of 100 mm, approximately 7854 mm². The pressure on the high-pressure side was 1 atmosphere, or 1013 hPa. The measurement temperature was 23°C, and the sample was set with the inorganic oxide layer side facing the high-pressure side. The pressure on the low-pressure side was measured using an MKS Balatron 615A01TRC diaphragm pressure gauge. The gases used are helium (99.99% or higher), argon (99.99% or higher), and neon (99.99%). The high-pressure side has a capacity of approximately 1000 ml, and the low-pressure side has a capacity of 24.42 ml. After the sample is placed in the measurement cell, both the high-pressure and low-pressure cells are evacuated using a turbomolecular pump for approximately 24 hours until the pressure is below 1.0 Pa. The vacuum pump was disconnected, and high-pressure gas was introduced. The pressure rise on the low-pressure side was measured until a constant slope was reached, and the permeability was measured. The gas permeability was calculated from the slope of the pressure rise.

[0095] Oxygen transmission rate (OTR) OTR was measured using a MOCON OX-TRAN 2 / 22H oxygen permeability analyzer in accordance with ISO 15105-2, under conditions of 23°C and 65% humidity.

[0096] Water vapor transmission rate (WVTR) WVTR was measured in accordance with ISO 15106-2 using a MOCON PERMATRAN-W 3 / 34G water vapor transmission rate analyzer under conditions of 40°C and 90% RH.

[0097] The polyester resin used in the roll film is described below.

[0098] Polyester resin Polyester resin A The basic aluminum acetate and diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate (chemical formula 4) were polymerized using terephthalic acid and ethylene glycol as polymerization catalysts. The basic aluminum acetate content in the synthesized polyester resin was 30 ppm.

[0099] Polyester resin B Terephthalic acid and ethylene glycol were polymerized using antimony trioxide and triethyl phosphate as polymerization catalysts. The antimony trioxide content in the synthesized polyester resin was 250 ppm.

[0100] Polyester resin C The polyester resin was polymerized using terephthalic acid and ethylene glycol as polymerization catalysts, with antimony trioxide used as the catalyst. Amorphous silica with an average particle size of 1.3 μm was added during polymerization. The antimony trioxide content in the polyester resin is 200 ppm. The amorphous silica content is 35,000 ppm.

[0101] Polyester resin D The polyester resin was polymerized using terephthalic acid and ethylene glycol as polymerization catalysts, along with antimony trioxide and triethyl phosphate. Amorphous silica with an average particle size of 2.4 μm was added during polymerization. The antimony trioxide content in the polyester resin was 250 ppm. The amorphous silica content was 7200 ppm.

[0102] A roll film manufactured using the aforementioned polyester resin will be described.

[0103] Biaxially oriented polyester film A Three extruders were used to produce a two-layer, three-component film with the same composition on both surface layers. The resin, melted at 280°C, was passed through a filter to remove impurities larger than 25 μm, then extruded and solidified in contact with a cooling roll temperature-controlled to 28°C. The solidified film was preheated using a group of rolls with gradually increasing temperatures from 72°C to 118°C. The film was stretched 1.2 times in the longitudinal direction between nip rolls heated to 118°C at different speeds. This stretching process was repeated until the film was stretched 4.5 times. Next, the film was stretched 4.0 times using a tenter-type transverse stretcher, with the temperature gradually increased from 94°C to 145°C. After that, it was heat-treated at 247°C for 1.5 seconds, followed by a temperature reduction to 230-194°C for 2.3 seconds. This treatment resulted in a 4.9% relaxation treatment. The film was then cooled to room temperature and wound up. By adjusting the extrusion rate of the extruder, the resin layers constituting each surface layer were made 1.3 μm thick after stretching. The resin layer forming the central core was made 9.4 μm thick after stretching. The surface layer was prepared by mixing polyester resin A and polyester resin C (resin A 91.9%, resin C 8.1%), adjusting the amount of amorphous silica in the surface resin layer to 2850 ppm. The core layer was made of polyester resin A. Corona treatment after stretching (treatment conditions: discharge power density 6.0 W·min / m) 2 The process was carried out to ensure that the diiodomethane contact angle was 23° or greater. The film was slit to a width of 2000 mm and a length of 50000 m so that it could fit into the vapor deposition apparatus. The tension (113 N / m) and contact crawl pressure (686 N / m) were adjusted, and the film was wound onto a metal tube to form a roll film.

[0104] Biaxially oriented polyester film B Three extruders were used to produce two types of three-layer films with the same composition on both surface layers. The resin, melted at 285°C, was passed through a filter to remove foreign matter larger than 25 μm, then extruded and solidified in contact with a cooling roll temperature-controlled to 35°C. The solidified film was preheated using a group of rolls with gradually increasing temperatures from 70°C to 134°C. The film was stretched 1.2 times in the longitudinal direction between nip rolls heated to 134°C at different speeds. This stretching process was repeated until the film was stretched 4.5 times. Next, the film was stretched 4.3 times using a tenter-type transverse stretcher, with the temperature gradually increased from 143°C to 154°C. After that, it was heat-treated at 245°C for 1.5 seconds, followed by a temperature reduction to 227°C to 150°C for 2.3 seconds. This treatment resulted in a 4.4% relaxation treatment. The film was then cooled to room temperature and wound up. The extrusion rate of the extruder was adjusted so that each surface layer of resin was 1.0 μm thick after stretching. The resin layer forming the central core was 10.0 μm thick after stretching. The surface layer was prepared by mixing polyester resin B and polyester resin D (resin B 87.5%, resin D 12.5%), adjusting the amount of amorphous silica in the surface resin layer to 900 ppm. The core layer was made of polyester resin B. Corona treatment after stretching (treatment conditions: discharge power density 6.6 W·min / m) 2 The process was carried out to ensure that the diiodomethane contact angle was 23° or greater. The film was slit to a width of 2000 mm and a length of 50000 m so that it could fit into the vapor deposition apparatus. The tension (90 N / m) and contact crawl pressure (480 N / m) were adjusted, and the film was wound onto a metal tube to form a roll film.

[0105] (Example 1) Roll 1, shown in Table 1, was placed in the deposition apparatus (Figure 2) and deposition was performed. Roll 1 was set in the electron beam deposition apparatus. The crucible was filled with alumina and silica with a purity of 99% or higher. After the deposition apparatus was evacuated, the set roll film was pulled out from the unwinding roll, and 500 sccm of argon gas was introduced for processing at a power of 0.25 W / m. 2 Plasma treatment was performed using sec. A mixed film of alumina and silica was laminated as an inorganic layer on a coating roll cooled to -20°C. After lamination of the alumina-silica, static electricity was removed and the film was peeled off the coating roll. The film thickness and composition were measured using an X-ray fluorescence film thickness gauge, and the electron gun was controlled to achieve a film thickness of 13 nm and a composition of 45%. After winding on a winding roll and opening to the atmosphere, the transparent gas barrier film was sampled and the WVTR and OTR were measured. The results are shown in Table 2. Table 2 shows the transmittance of helium, neon, and argon.

[0106] [Table 1]

[0107] [Table 2]

[0108] (Example 2) The procedure was the same as in Example 1, except that roll 2 shown in Table 1 was placed in the deposition apparatus (Figure 2) and deposition was performed.

[0109] (Comparative Example 1) The procedure was the same as in Example 1, except that roll 3 shown in Table 1 was placed in the deposition apparatus (Figure 2) and deposition was performed.

[0110] (Comparative Example 2) The procedure was the same as in Example 1, except that roll 4 shown in Table 1 was placed in the deposition apparatus (Figure 2) and deposition was performed. [Industrial applicability]

[0111] The present invention provides a transparent barrier film with excellent barrier performance by forming a dense inorganic oxide layer with few defects on a biaxially oriented polyester film without the need for anchor coatings or the like. [Explanation of symbols]

[0112] 1: Contact Roll 2: Rolled film 3: Unwinding Roll 4: Biaxially oriented polyester film 5: Plasma treatment device 6: Coating Roll 7: Electron gun 8: Electron beam 9: Vapor deposition materials 10: Static eliminator 11: Optical film thickness gauge 12: X-ray fluorescence film thickness gauge 13: Reel roll 14: Substrate (biaxially oriented polyester film) 15: Droplets (e.g., diiodomethane) 16: Tangent

Claims

1. A biaxially oriented polyester roll film for use in a laminate formed by laminating an inorganic oxide on at least one side of a biaxially oriented polyester film, characterized in that the surface on which the inorganic oxide is laminated satisfies the following requirements (1) to (4), and the winding hardness of the roll film is such that the R value is 25 or less and 15 or more when measured with a reband hammer. (1) Area 4×10 －１２ I understand ２ The number of microscopic protrusions less than 3 nm in height per surface is between 250 and 600. (2) Area 4×10 －１２ I understand ２ The number of microscopic protrusions with a height of 3 nm or more per surface is between 300 and 600. (3) The arithmetic mean height Sa is 0.010 μm or more and 0.025 μm or less. (4) The contact angle of diiodomethane is 23° or greater.

2. The biaxially oriented polyester roll film according to claim 1, wherein the contact angle of diiodomethane on the film surface where inorganic oxides are laminated is maintained at 23° or more after 200 days or more from the date of manufacture.

3. A transparent barrier film obtained by laminating an inorganic oxide onto a biaxially oriented polyester roll film as described in claim 1.

4. The ratio obtained by dividing the helium gas permeability of the transparent barrier film described in claim 3 by the permeability of the roll film, and the same relationship obtained by dividing the ratio by the ratio of the argon gas permeability of the transparent barrier film by the argon permeability of the roll film, satisfy the following formula [Formula 1], and the argon permeability is 10 mL (stp) / m ２ A transparent barrier film characterized by having a pressure of less than 24h·MPa. (PtHe / PfHe) / (PtAr / PfAr)≦2.0... [Formula 1]

5. A method for producing a transparent barrier film according to claim 3 or 4, characterized by subjecting a biaxially oriented polyester roll film according to claim 1 or 2 to argon plasma treatment, and then laminating an inorganic oxide.

Images