JP4345149B2 - Barrier film - Google Patents

Description

【００４３】
なお、表中の記号は次の通りである。
【００４４】
ＰＥＴ：ポリエチレンテレフタレート
ＰＥＴ／Ｉ：イソフタル酸共重合ポリエチレンテレフタレート
ＰＥＴ／Ａ：アジピン酸共重合ポリエチレンテレフタレート
【００４５】
【発明の効果】
本発明によりリサイクル性に優れたバリア用二軸延伸フィルムおよびバリアフィルムを提供することができ、包装材料や工業材料として多くの用途に使用することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biaxially stretched film and a barrier film suitable for obtaining a barrier film having excellent recyclability.
[0002]
[Prior art]
In order to store food and chemicals for a long period of time, it is necessary to carry out packaging with an excellent barrier property, which has an effect of blocking the entry of oxygen and water vapor from the outside air that promotes spoilage and deterioration. Examples of the film having excellent gas barrier properties used for this purpose include those obtained by forming a barrier material (a resin having high gas barrier properties itself) into a film or a sheet, and those obtained by laminating a barrier material on the film. Specific examples of the latter include, for example, a film on which a metal or metal oxide such as aluminum, alumina, or silica is deposited, or a film on which a polymer having high gas barrier properties such as polyvinylidene chloride or ethylene vinyl alcohol copolymer is laminated. Are known.
[0003]
[Problems to be solved by the invention]
However, the conventional barrier film has the following problems.
That is, for example, although a polyvinylidene chloride laminated film exhibits good oxygen and water vapor barrier properties, it generates chlorine gas during incineration, and there is a concern about adverse effects on the global environment.
[0004]
On the other hand, a film in which an oxygen silicon film, an aluminum oxide film, or an aluminum film is formed by vapor deposition exhibits good barrier properties, and has recently been used for various applications. However, it is difficult to separate the metal in the deposited barrier film, so that it is difficult to reuse the film, and there is a problem in incineration because it is almost impossible to remove the metal or metal oxide.
[0005]
The present invention intends to provide a barrier film and a barrier film excellent in recyclability in response to a demand for improvement in recyclability against the background of environmental problems.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, in the present invention, a B layer is laminated on at least one side of a polyester layer (A layer) having 80 mol% or more of ethylene terephthalate and / or ethylene naphthalate units. It is a barrier film formed by depositing metal, metal oxide or silicon oxide on the B layer surface of the axially stretched film ,
And a barrier film resin constituting the B layer is dissolved 70% with an aqueous solution of PH8～14.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The polyester constituting the A layer in the present invention is a general term for polymers having an ester bond as the main bond chain of the main chain, but from the viewpoint of heat resistance, long-term stability, film-forming property, etc., ethylene terephthalate and The ethylene naphthalate unit needs to be 80 mol% or more, preferably 90 mol% or more, particularly preferably 95 mol% or more. Furthermore, it is preferable that melting | fusing point of polyester A is 245 degreeC or more and 280 degrees C or less, More preferably, it is 250 degreeC or more and 275 degrees C or less.
[0008]
The polyester of the present invention can be copolymerized with other components within a range that does not impair the properties. Examples of the dicarboxylic acid component include diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethane in addition to terephthalic acid and naphthalenedicarboxylic acid. Aromatic dicarboxylic acids such as dicarboxylic acid, 5-sodiumsulfoisophthalic acid, phthalic acid, isophthalic acid, oxalic acid, succinic acid, eicoic acid, adipic acid, sebacic acid, dimer acid, dodecanedioic acid, maleic acid, fumaric acid An aliphatic dicarboxylic acid such as cycloaliphatic dicarboxylic acid, an oxycarboxylic acid such as p-oxybenzoic acid, a polyfunctional acid such as trimellitic acid and pyromellitic acid can be used. On the other hand, as the glycol component, in addition to ethylene glycol, for example, propanediol, butanediol, pentanediol, hexanediol, neopentyl glycol, triethylene glycol and other aliphatic glycols, cyclohexanedimethanol An alicyclic glycol such as thiol, an aromatic glycol such as bisphenol A and bisphenol S, diethylene glycol, and polyalkylene glycol can be used. Furthermore, polyethers such as polyethylene glycol and polytetramethylene glycol can be copolymerized. Among these, polyethylene terephthalate, isophthalic acid copolymerized polyethylene terephthalate, naphthalene dicarboxylic acid copolymerized polyethylene terephthalate, and polynaphthalene terephthalate are particularly preferable from the viewpoint of heat resistance, biaxial stretchability, and productivity.
[0009]
These dicarboxylic acid components and glycol components may be used in combination of two or more, or two or more polyesters may be blended and used. Further, it may be coextruded into two or more layers and used as a laminated film.
[0010]
In the above polyester, additives such as a heat stabilizer, an oxidation stabilizer, a weather stabilizer, an ultraviolet absorber, an organic lubricant, a pigment, a dye, an organic or inorganic substance are added to the extent that the effects of the present invention are not impaired. Fine particles, fillers, nucleating agents and the like can be blended.
[0011]
In the present invention, from the viewpoint of recyclability, it is necessary to laminate a layer (B layer) made of a resin that dissolves at least 70% in an aqueous solution of pH 8 to 14 on at least one side of the polyester A layer.
[0012]
The resin constituting the B layer of the film in the present invention needs to be dissolved 70% or more in an aqueous solution having a pH of 8 to 14 in an alkali dissolution test described later, preferably 80% or more, more preferably 90% or more. . “Dissolving 70% or more in an aqueous solution of pH 8-14” means dissolving 70% or more at any pH within the range. When 70% or more is dissolved in an aqueous solution having a pH of 8 to 14, it becomes possible to remove the B layer by a recycling process using an alkaline solution, and a barrier material such as a metal or metal oxide layer deposited on the B layer, or For example, it becomes easy to remove a barrier material represented by, for example, polyvinylidene chloride, which is laminated on the B layer, and the film is very suitable in terms of environmental properties. The aqueous solution having a pH of 8 to 14 is an alkaline aqueous solution, and examples thereof include alkaline aqueous solutions such as sodium hydroxide, calcium hydroxide, and ammonium hydroxide. In the region where the pH is high, it is preferable in terms of improving the solubility of the resin, but conversely, since the alkaline environment is strong, there is a concern that the working environment may deteriorate, so the pH of the aqueous solution is preferably pH 8.5-12. More preferably, the pH is 8-11. Moreover, the temperature of aqueous solution becomes like this. Preferably it is 50 to 100 degreeC, More preferably, it is 60 to 90 degreeC. By setting the temperature of the aqueous solution in the above range, in addition to improving the solubility of the resin layer, the time required for dissolution is also shortened, which is very preferable from the viewpoint of improving work efficiency.
[0013]
In the present invention, a resin mainly composed of polylactic acid can be used as a resin that dissolves 70% or more in an aqueous solution having a pH of 8 to 14. Here, polylactic acid is used as, for example, D-lactic acid homopolymer, L-lactic acid homopolymer, D-lactic acid / L-lactic acid copolymer, D-lactic acid / hydroxycarboxylic acid copolymer, and blends of polylactic acid and polymers other than polylactic acid. it can. In the case of the blend, the polylactic acid is preferably 60 to 95% by weight, more preferably 70 to 95% by weight. The polymer mainly composed of polylactic acid is mainly composed of an L-lactic acid component, and the content of the D-lactic acid component is preferably 0 to 30% by weight, more preferably in terms of heat resistance and dimensional stability. The content of the D-lactic acid component is 0 to 20% by weight.
[0014]
The resin mainly composed of polylactic acid in the present invention can be obtained, for example, by the following method.
[0015]
That is, as raw materials, hydroxycarboxylic acids such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, etc. can be used in combination with D-lactic acid and / or L-lactic acid as a main component. Furthermore, dicarboxylic acids and glycols can also be used. A polymer mainly composed of polylactic acid can be obtained by a method of directly dehydrating polycondensation of the raw materials or a method of ring-opening polymerization of the cyclic ester intermediate. For example, when producing by direct dehydration polycondensation, lactic acid or lactic acid and hydroxycarboxylic acid are preferably subjected to azeotropic dehydration condensation in the presence of an organic solvent, particularly phenyl ether solvent, and particularly preferably polymerized by azeotropy. As a result, a high molecular weight polymer suitable for the present invention can be obtained. The molecular weight of the polymer is preferably in the range of 10,000 to 1,000,000, more preferably 50,000 to 500,000 from the viewpoint of moldability as a film.
[0016]
Further, the resin mainly composed of polylactic acid in the present invention includes polyglycolic acid having a hydroxycarboxylic acid component as a constituent, polybutyric acid polyhydroxybutyrate and the like, and polyethylene terephthalate having a dicarboxylic acid component and a glycol component as constituents. (PET), polypropylene terephthalate (PPT), polyethylene-2,6-naphthalate (PEN), polybutylene terephthalate (PBT), polyhexamethylene terephthalate (PHT), polyethylene isophthalate (PEI), polycyclohexanedimethylene terephthalate (PCT) ), A polyester such as polybutylene succinate, or a blend with a copolymer based on these polyesters. In the case of a copolymer, it may be a random copolymer or a block copolymer.
[0017]
In addition, other alkaline water-soluble polymers can be added as long as the effects of the present invention are not impaired. Examples of other alkali-degradable polymers that can be used include cellulose acetate, cellulose, starch, and polyvinyl alcohol. In the present invention, preferably, a resin mainly composed of polylactic acid can exhibit excellent alkali solubility. The above-mentioned resin mainly composed of polylactic acid may contain various additives other than particles as long as the alkali solubility is not impaired, if necessary. For example, an organic lubricant such as a flame retardant, an antioxidant, an antifungal agent, a heat stabilizer, a lubricant, a crystal nucleating agent, an ultraviolet absorber, a colorant, a terminal blocking agent, a fatty acid ester, a wax, or a polysiloxane may be blended. it can.
[0018]
The film of the present invention needs to be a biaxially oriented film from the viewpoints of heat resistance, mechanical strength, dimensional stability, vapor deposition of a barrier material, and laminating properties. A biaxially oriented film is a non-stretched sheet or film that is made by stretching about 2 to 6 times in the longitudinal direction and in the width direction, and shows a biaxially oriented pattern by wide-angle X-ray diffraction. Say. The biaxial stretching method may be either simultaneous biaxial stretching or sequential biaxial stretching.
[0019]
The thickness of the film of the present invention is not particularly limited, and may be arbitrarily selected according to the use, but is 0.1 to 1000 μm, preferably 0.5 to 500 μm, and more preferably 5 to 30 μm. . Moreover, when using especially for vapor deposition, it is preferable that it is 5-20 micrometers.
[0020]
As a film structure, it is comprised from the layer (B layer) which consists of a polyester layer (A layer) which is 80 mol% or more of ethylene terephthalate and / or an ethylene naphthalate unit, and resin which melt | dissolves 70% or more by pH 8-14 aqueous solution, In addition to the two layers A / B with the layer B as the vapor deposition surface or the barrier material lamination surface, a layered structure of three layers of C / A / B, A / C / B, or even a multilayer of three layers or more. Good. The lamination thickness ratio can also be set arbitrarily, but it is preferable that d (A)> d (B), more preferably d (A)> 2 * d (B), and preferably 0. 01 μm ≦ d (B) ≦ 5 μm, more preferably 0.01 μm ≦ d (B) ≦ 3 μm. Here, d (A) is the thickness (μm) of the A layer, and d (B) is the thickness (μm) of the B layer. Furthermore, layers other than these may be laminated, and specific examples include an antistatic layer, a mat layer, a hard coat layer, a slippery coat layer, an easy adhesion layer, and an adhesive layer.
[0021]
In the film of the present invention, the melting subpeak (Ts) of the film is preferably 120 to 245 ° C. from the viewpoint of dimensional stability, more preferably 140 to 235 ° C., further preferably 160 to 225 ° C. from the viewpoint of vapor deposition. It is. If Ts is less than 120 ° C., the thermal dimensional stability deteriorates, which is not preferable. Further, if Ts exceeds 245 ° C., the film becomes brittle, which is not preferable.
[0022]
In the film of the present invention, the plane orientation coefficient (fn (A)) of the polyester A layer is preferably 0.14 to 0.180, more preferably 0.15 to 0.17. When the plane orientation coefficient is less than 0.14, the orientation of the film is lowered, so that the film tends to be stretched with respect to strength reduction or external force, and the workability is lowered. Also, if the plane orientation coefficient exceeds 0.18, it is not preferable because physical property spots and whitening in the width direction of the film occur.
[0023]
In the present invention, it is preferable that the plane orientation coefficient (fn (B)) of the B layer satisfies the relational expression of fn (A) ≧ fn (B) from the viewpoint of gas barrier properties and adhesion to the deposited layer. , Fn (B) is preferably 0.005 to 0.14, more preferably 0.01 to 0.1.
[0024]
In the present invention, the birefringence (Δn) of the film A layer is preferably −0.05 to −0.001, more preferably −0.03 to −0.01. Here, the birefringence (Δn) is obtained by Δn = Nx (the refractive index in the vertical direction) −Ny (the refractive index in the horizontal direction). The fact that Δn is minus (−) indicates that the orientation in the film width direction is stronger than in the longitudinal direction. When birefringence becomes larger than -0.001, the tensile property of the width direction at the time of vapor deposition processing or the lamination will show the tendency to fall. Further, if it is less than -0.05, the orientation in the width direction becomes too stronger than the orientation in the longitudinal direction. As a result, the balance between the orientation in the longitudinal direction and the width direction is excessively broken and the flatness such as thickness unevenness is deteriorated. May show a tendency to
[0025]
In the film of the present invention, the refractive index in the thickness direction of the A layer is preferably 1.48 to 1.51, and more preferably 1.49 to 1.5. If the refractive index in the thickness direction is less than 1.48, troubles may occur during processing due to cleaving of the film. On the other hand, if it exceeds 1.51, processing characteristics and printability may be deteriorated.
[0026]
The intrinsic viscosity (measured in 25 ° C. orthochlorophenol) of the polyester A layer in the present invention after film formation is 0.40 to 1.20 dl / g, preferably 0.50 to 0.85 dl / g, more preferably Those in the range of 0.55 to 0.75 are suitable for the contents of the present invention.
[0027]
Furthermore, from the point which improves adhesiveness with printing ink etc., the amount of carboxyl terminal groups of the polyester A layer is preferably 25 to 55 equivalent / ton or more, more preferably 30 to 40 equivalent / ton.
[0028]
In the present invention, the thermal shrinkage rate at 150 ° C. for 30 minutes is preferably 0.1 to 5.0% in the film longitudinal direction and −2 to 1% in the width direction, more preferably 1.0 in the film longitudinal direction. -3.0% and -1-0% in the width direction. Here, the minus (−) value of the heat shrinkage rate indicates elongation.
[0029]
In this invention, it is preferable that the breaking strength of a film longitudinal direction and the width direction is 150-400 MPa, More preferably, it is 200-350 MPa. When the breaking strength is less than 150 MPa, the film strength is lowered, and the workability and strength after bag making are inferior. On the other hand, if the breaking strength exceeds 400 MPa, the flexibility of the film during processing is lowered, which is not preferable.
[0030]
In the present invention, the breaking elongation in the film width direction is preferably 50 to 180%, more preferably 90 to 150%. In addition, it is preferable that (longitudinal breaking elongation / breaking elongation in the width direction) is 1.1 to 2.0 from the viewpoint of developing appropriate tensile properties in the width direction during vapor deposition and improving vapor deposition properties. It is not particularly limited.
[0031]
Furthermore, the film of the present invention may be subjected to various coatings, and is not particularly limited. However, in consideration of production and environmental aspects, a film in which an aqueous or water-dispersed coating agent is applied during film formation is preferable.
[0032]
In the film of the present invention, the relationship between the center line average roughness Ra (A) of the A layer surface and the center line average roughness Ra (B) of the B layer surface is such that Ra (A) ≧ Ra (B). Is preferable from the viewpoint of achieving both workability and workability. Further, from the viewpoint of gas barrier properties, Ra (B) is preferably 0.001 to 0.05 μm, more preferably 0.005 to 0.03. Further, from the viewpoint of winding characteristics and workability, Ra (A) is preferably 0.01 to 0.1 μm, more preferably 0.02 to 0.07 μm, and still more preferably 0.03 to 0.05 μm. is there.
[0033]
The particles contained in the film of the present invention are not particularly limited as long as an inert material is added to each of resins mainly composed of polyester and polylactic acid, but external particles such as internal particles, inorganic particles, and / or organic particles. The particles arbitrarily selected from the above are preferably contained in an amount of 0.01 to 10% by weight, more preferably 0.02 to 1% by weight. The average particle diameter of the contained particles is preferably 0.001 to 10 μm, more preferably 0.01 to 2 μm. Use of particles having an average particle diameter exceeding 10 μm is not preferable because defects of the film are likely to occur. Examples of the inorganic particles and / or organic particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay and the like, and styrene, silico. -Organic particles etc. containing acrylic acid and the like as constituent components. Of these, inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, alumina and calcium carbonate are preferred. These internal particles, inorganic particles and / or organic particles may be used in combination of two or more.
[0034]
Prior to vapor deposition, the film surface of the present invention may be subjected to appropriate surface treatment, that is, low-temperature plasma treatment, corona discharge treatment, or the like.
[0035]
The film of the present invention can be used as a barrier film for various industrial materials, agricultural materials, packaging materials, and the like.
[0036]
Next, although the manufacturing method of this invention is demonstrated, it is not necessarily limited to this.
[0037]
Polylactic acid composed of polyethylene terephthalate (layer A) having an intrinsic viscosity of 0.04% by weight containing inorganic particles (for example, wet-process silica particles having an average particle diameter of 1.2 μm) and L-lactic acid / D-lactic acid (Contains 0.03% by weight of colloidal silica particles having an average particle size of 0.2 μm) (Layer B) is dried according to a conventional method, and then the layers A and B are polymer coextruded from adjacent dies and laminated and fused. The sheet-like melt is cooled and solidified on a cooling drum while applying an electrostatic force to produce a non-oriented film. The film is stretched 2.0 to 5.0 times in the longitudinal direction while heating at 70 to 130 ° C. to obtain a uniaxially oriented PET film. Further, the film was held by a clip and led into a tenter heated to 80 ° C. to 140 ° C., stretched 2.5 to 6.0 times in the width direction, and continuously in a heat treatment zone of 140 ° C. to 240 ° C. And heat treatment for 1 to 10 seconds. You may perform a 0-12% relaxation process as needed during this heat processing.
[0038]
The obtained film was vapor-deposited with a continuous vacuum vapor deposition machine to obtain a transparent vapor deposition polyester film in which an aluminum, aluminum oxide or silicon oxide vapor deposition layer was formed.
[0039]
[Methods for measuring physical properties and methods for evaluating effects]
The physical property measuring method and the effect evaluating method in the present invention are as follows.
(1) Melting point, melting of film Sub-peak film was measured by differential scanning calorimeter (DSC-2 type, manufactured by Parkin Elmer Co., Ltd.) at a heating rate of 10 ° C./min, and main melting peak temperature (melting point) Asked. In addition, Ts was defined as a sub-peak temperature generated by the transformation of the pseudocrystal generated during this measurement. Ts appears as a history of the heat treatment temperature during the film forming process. The unit is ° C.
(2) Refractive index, birefringence, plane orientation coefficient Measured with an Abbe refractometer using sodium D-line (wavelength 589 nm) as a light source. The plane orientation coefficient fn = (Nx + Ny) / 2−Nz obtained from the refractive indexes (Nx, Ny, Nz) in the longitudinal direction, the width direction, and the thickness direction was obtained by calculation.
(3) Centerline average roughness (Ra)
It measured using the high precision thin film level | step difference measuring device ET-10 made from a Kosaka laboratory. The measurement conditions are as follows, and the average value of 20 measurements was used as the value.
[0040]
・ Tip tip radius: 0.5μm
-Stylus load: 5mg
・ Measurement length: 1mm
・ Cutoff: 0.08mm
Details of detailed parameter definitions are shown, for example, in Jiro Nara “Surface roughness measurement method / evaluation method” (General Technology Center, 1983).
(4) Oxygen permeability According to ASTM D-3985, the oxygen permeability was measured at 20 ° C. and 0% RH using an oxygen permeability measuring device OX-TRAN100 manufactured by Modern Control.
(5) Water vapor transmission rate It measured on the conditions of 40 degreeC and 90% RH using the water vapor transmission rate meter PERMATRAN-W1A by Modern Control.
(6) About 3 g of the B layer is scraped from the alkali-soluble film and the weight is accurately measured, and the value is defined as G1. After stirring for 30 minutes at a temperature of 80 ° C. in 300 ml of a 2% by weight aqueous solution of sodium hydroxide, the aqueous solution was filtered with filter paper, washed thoroughly with pure water, and the residue on the filter paper was dried at 110 ° C. × 1 hour, then 23 ° C. Then, after cooling in a 60% humidity atmosphere for 1 hour and adjusting the humidity, the weight of the residue is measured and the value is defined as G2. The alkali solubility is obtained by the following formula.
Alkali solubility = (G1-G2) / G1 × 100
Next, the alkali solubility is evaluated as ◎ for those having an alkali solubility of 90% or more, ◯ for 70% to less than 90%, △ for 50% to less than 70%, and x for less than 50%. did.
(7) The recoverable aluminum vapor-deposited film was stirred for 1 hour at 5000 ° C. in 5000 ml of a 2 wt% aqueous solution of sodium hydroxide and washed with water. The recoverability was evaluated by visually classifying the degree of separation between the aluminum and the film as follows. The case where aluminum adhered to the film was rated as “X”, the case where aluminum was not adhered as “◯”, and the intermediate one as “Δ”.
[0041]
【Example】
Next, the present invention will be described based on examples, but is not necessarily limited thereto.
Example 1
Polyethylene terephthalate (melting point 255 ° C.) pellets (intrinsic viscosity 0.65 dl / g) containing 0.15% by weight of agglomerated silica particles having a particle diameter of 1.2 μm as the A layer and agglomerated silica having an average particle diameter of 1.2 μm as the B layer Adjacent to each other after drying polylactic acid composed of L-lactic acid / D-lactic acid (composition ratio 90/10, weight average molecular weight 180,000) containing 0.04% by weight of particles until the water content becomes 30 ppm. The polymer of the A layer and the B layer was coextruded from the die thus obtained, laminated and fused, and the sheet-like melt was cooled and solidified on a cooling drum while applying an electrostatic force to prepare an unstretched film. The film was heated to 90 ° C. and stretched 3.4 times in the longitudinal direction to obtain a uniaxially stretched film. The film is held in a tenter heated to 100 ° C. by gripping the flip, continuously stretched 4.0 times in the width direction in a zone heated to 110 ° C., subjected to heat treatment for 5 seconds, and a film thickness of 12 μm. Film was obtained. Furthermore, aluminum vapor deposition was given to this film, and the aluminum vapor deposition film by which film thickness 45nm was laminated | stacked was obtained. As shown in Table 2, it can be seen that excellent recyclability is exhibited.
Example 2
The polylactic acid of layer B is L-lactic acid / D-lactic acid (composition ratio 94/6, weight average molecular weight 190,000), and an unstretched film is prepared in the same manner as in Example 1 by adding the polymer and particles shown in Table 1. did. The film was simultaneously biaxially stretched at 95 ° C. 3.5 times in the longitudinal direction and 3.6 times in the transverse direction, and heat treated for 10 seconds to obtain a film having a thickness of 12 μm. Furthermore, aluminum vapor deposition was given to this film, and the aluminum vapor deposition film by which film thickness 45nm was laminated | stacked was obtained. As shown in Table 2, it can be seen that excellent recyclability is exhibited.
Example 3
The B layer was polylactic acid (weight average molecular weight 160,000) having a composition ratio of L-lactic acid / D-lactic acid and hydroxycaproic acid of 82/4/14. The 12 μm biaxially stretched film shown in Table 1 was obtained by changing the film forming conditions. When an alumina (aluminum oxide) vapor deposition was performed to obtain a film having a thickness of 44 nm laminated, excellent recyclability was exhibited as shown in Table 2. Example 4
The polylactic acid of layer B is L-lactic acid / D-lactic acid (composition ratio 95/5, weight average molecular weight 160,000), and the film formation conditions of Example 1 are changed by adding the polymer and particles shown in Table 1 to Table 1. The biaxially stretched film of 12 μm shown in 1 was obtained. When silicon oxide vapor deposition was performed to obtain a film having a film thickness of 44 nm, excellent recyclability was exhibited as shown in Table 2.
Comparative Example 1
Films shown in Table 1 were obtained in the same manner as in Example 1 using the polymers shown in Table 1 and changing the film forming conditions. Further, the film was vapor-deposited to obtain a vapor-deposited film on which aluminum (45 nm) was laminated. As shown in Table 2, the recyclability was inferior.
Comparative Example 2
Films shown in Table 1 were obtained in the same manner as in Example 1 using the polymers shown in Table 1 and changing the film forming conditions. Further, the film was vapor-deposited to obtain a vapor-deposited film on which a silicon oxide film (45 nm) was laminated. As shown in Table 2, the recyclability was inferior.
[0042]
[Table 1]

[0043]
The symbols in the table are as follows.
[0044]
PET: Polyethylene terephthalate PET / I: Isophthalic acid copolymerized polyethylene terephthalate PET / A: Adipic acid copolymerized polyethylene terephthalate
【The invention's effect】
According to the present invention, a biaxially stretched film for a barrier and a barrier film excellent in recyclability can be provided, and the film can be used for many applications as a packaging material or an industrial material.

Claims (2)

Metal, metal oxide, or silicon oxide is vapor-deposited on the B layer surface of a biaxially stretched film formed by laminating a B layer on at least one surface of a polyester layer (A layer) having an ethylene terephthalate and / or ethylene naphthalate unit of 80 mol% or more. Is a barrier film made of,
And, a barrier film resin constituting the B layer is characterized by dissolving 70% or more with an aqueous solution of PH8～14. The barrier film according to claim 1, wherein the B layer is composed of a resin mainly composed of polylactic acid.