JP2002309023A - Method for producing gas barrier film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance gas barrier film using a polypropylene film as a substrate. SOLUTION: This method for producing the gas barrier film is characterized by longitudinally orienting an unoriented film obtained by melt-extruding a polypropylene-based resin, subjecting the longitudinally oriented film to a corona discharge treatment, coating the corona-treated surface of the longitudinally oriented film with a water-soluble resin coating solution comprising a water-soluble acrylic resin, a water-soluble urethane resin and polyvinyl alcohol, laterally orienting the film, and then forming a vacuum-deposited inorganic oxide film on the coated surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a gas barrier film having excellent oxygen gas barrier properties, water vapor barrier properties, transparency, solvent resistance and lamination strength, which are used for protecting foods, industrial goods and pharmaceuticals. About the method.

[0002]

2. Description of the Related Art Many gas barrier films and packaging materials using the same are already known. Aluminum foil has the most perfect gas barrier properties, but it has a weak pinhole strength by itself and cannot be used except for special cases, and is almost used as an intermediate layer of a laminate film. Although the gas barrier properties of this laminated film are almost perfect, it has drawbacks such that the contents are not visible due to opacity, and it is difficult to judge whether or not the heat seal has been securely performed.

As other gas barrier films, polyvinylidene chloride (hereinafter "PVDC") films and coating films are well known. In particular, PVDC coating films are well known and are often used as a base film for lamination when barrier properties against oxygen and water vapor are required. PVDC has little hygroscopicity,
Since it has good gas barrier properties even under high humidity, various substrates are used as coating substrates regardless of moisture permeability. For example, biaxially oriented polypropylene (OP
P), biaxially oriented nylon (ONy), biaxially oriented polyester (in the case of biaxially oriented polyethylene terephthalate (O
PET)) and cellophane films. The laminated film is used for various food packaging, regardless of dryness or water, making use of gas barrier properties. However, after these packaging materials have been used,
It will be disposed of as general waste from households.
Since VDC generates hydrogen chloride gas by combustion, transfer to other materials is strongly desired.

On the other hand, as a gas barrier film, a metal film of aluminum or the like or aluminum oxide or silicon oxide or the like is deposited on a plastic film. It is proposed to prevent oxidation of the contents and maintain the quality for a long period of time. For example, Japanese Patent Publication No. 53-12953 and Japanese Patent Application Laid-Open No. 4-353532 have a thickness of 5 to 300 μm.
m on at least one surface of a flexible plastic film such as polyethylene terephthalate, cellophane, nylon, polypropylene, or polyethylene.
y (x = 1,2, y = 0,1,2,3) is a silicon oxide having a thickness of 100 to 3000 angstroms, provided with a transparent glassy thin film layer. A transparent flexible plastic film having the same is disclosed.

In general, when the film material is a resin having a polar group such as polyester, nylon or cellophane, generally, the adhesion strength between the film and the inorganic oxide film is high and the gas barrier property is good. It is. However, even if a vapor-deposited film made of an inorganic oxide is formed on the surface of a film having no polar group such as polypropylene, a stable gas barrier property that can withstand practical use cannot be obtained. In other words, since the adhesion between the polypropylene film and the vapor-deposited film is not sufficient, when laminating a heat-sealable resin to impart heat-sealing properties to this vapor-deposited material, the laminate is used to form a bag or cover seal. In the case of secondary processing, these bags are used, the contents are filled in a container, or when boiled or retorted, the external stress or heat is applied to the molded product, and the inorganic oxide thin film becomes a polypropylene film. There is a problem that the film is further peeled off, the gas barrier property is reduced, and it cannot be put to practical use.

Such a problem is described, for example, in Japanese Patent Application Laid-Open No. 2000-2
As described in No. 63722, the use of an organic solvent-based resin coating solution such as ethyl acetate, toluene, and methyl ethyl ketone tends to be improved. However, in consideration of environmental problems, effects on the human body, costs, etc., the development of a water-based coating agent. Is desired. JP-A-7-126419, JP-A-8-128
JP-A-245816 discloses an example in which a polypropylene film is coated with a water-soluble resin coating solution containing polyvinyl alcohol (PVA), and then a metal or inorganic compound is deposited. However, in these examples, since the resin component forming the coating layer after drying is mainly composed of polyvinyl alcohol, even if the oxygen barrier performance on the low humidity side is good, a significant decrease in the barrier performance occurs on the high humidity side, Furthermore, there remains a problem that the adhesion strength between the polypropylene film and the coating layer or between the coating layer and the deposited thin film layer is not sufficient. Japanese Patent Application Laid-Open No. 8-92400 discloses an ethylene / vinyl alcohol copolymer (hereinafter referred to as “EVO”) instead of PVA.
H)) is disclosed. In the case of EVOH, the reduction in barrier properties under high humidity is improved, but the adhesion between the olefin resin layer and the AC layer is reduced. This does not satisfy both gas barrier properties and adhesion.

[0007]

SUMMARY OF THE INVENTION The present invention is based on the current situation of gas barrier films as described above, and is intended as an inexpensive packaging material to replace PVDC-coated OPP (so-called K-OP). Eco-friendly water-based AC agent with no solvent odor,
It is a gas barrier film with an inorganic oxide thin film deposited, and has excellent gas barrier properties not only on the low humidity side but also on the high humidity side,
Further, it is an object of the present invention to provide a gas barrier film which does not cause the inorganic oxide thin film to peel off at the time of secondary processing or use thereof and lowers gas barrier properties, and furthermore has excellent transparency and solvent resistance. .

[0008]

DISCLOSURE OF THE INVENTION The present invention has been accomplished as a result of intensive studies for the above objects, and is intended to stretch an unstretched film obtained by melt-extruding a polypropylene resin in the longitudinal direction. , A corona discharge treatment, and then a water-soluble acrylic resin (a), a water-soluble urethane resin (b) and a polyvinyl alcohol (c) on the corona-treated surface of the longitudinally stretched film. The following formula
A method for producing a gas barrier film, which comprises applying a water-soluble resin coating solution satisfying (1) to (3), stretching the film in the horizontal direction, and then forming a vapor-deposited inorganic oxide film on the coating surface. About.

[Formula 2] 50 wt% ≦ (a) + (c) ≦ 70 wt% (1) 30 wt% ≦ (b) ≦ 50 wt% (2) 1 ≦ (a) / (c) ≦ 3 (3)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, a specific water-soluble coating liquid is applied to a polypropylene base film by a so-called in-line coating method, stretched, and finally, an inorganic oxide is deposited. Good gas barrier properties can be obtained by combining the water-soluble acrylic resin (a), polyvinyl alcohol (c) and the inorganic oxide. Further, by combining the water-soluble urethane resin (b) and the polyvinyl alcohol (c), a strong bond between a hydroxyl group or a peroxide group on the corona discharge-treated polypropylene surface and a polar group contained in the (b) or (c) is obtained. And a strong bond between the inorganic or oxygen atom in the deposited thin film and the polar group contained in (b) or (c) is obtained, and finally, a sufficient adhesion strength between the substrate and the inorganic oxide deposited film is obtained. can get.

[0010] The polypropylene resin for the base layer is a propylene resin such as propylene homopolymer, propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene / 4-methylpentene-1 copolymer, etc. Ethylene resins such as low-density polyethylene and linear-polyethylene, or polypropylene resins modified with α, β-unsaturated carboxylic acids can be used. These may be used as a mixture of two or more kinds, or may be used by laminating. Further, depending on the purpose, it may contain a very small amount to several tens% of a lubricant, an antioxidant, an ultraviolet absorber, an antistatic agent, an antiblocking agent, an antibacterial agent, a nucleating agent and the like.

The water-soluble acrylic resin (a) used in the water-soluble resin coating solution is not particularly limited, but is preferably a colloidal dispersion type or a water-soluble type having a smaller particle size than an emulsion type in terms of wettability. Is preferred. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate,
One or more monomer units selected from those having a hydroxyl group such as -hydroxyethyl (meth) acrylate and 3-hydroxypropyl (meth) acrylate and those having an epoxy group such as glycidyl (meth) acrylate; Any water-dispersible (co) polymer may be contained. At this time, (meth) acrylic acid such as (meth) acrylamide, (meth) acrylic acid, sodium (meth) acrylate, and potassium (meth) acrylate It may contain a system monomer unit. Further, two or more kinds of (co) polymers having different constituent components may be used in combination.

The water-soluble acrylic resin (a) contributes to the oxygen barrier property together with the polyvinyl alcohol (c) to be described later, and it is preferable that both are 50 to 70% by weight in terms of solid content. If it is less than 50% by weight, sufficient gas barrier performance cannot be obtained. Conversely, if it exceeds 70% by weight, the gas barrier performance is good, but the solvent resistance in the case of printing on an inorganic oxide vapor-deposited film or the like is inferior.

The mixing ratio of the water-soluble acrylic resin (a) and the polyvinyl alcohol (c) is 1 ≦
It is preferable that (a) / (c) ≦ 3, and (a) /
When the value of (c) is less than 1, it is mainly composed of polyvinyl alcohol (c), which not only deteriorates the oxygen barrier property on the high-humidity side, but also causes peeling at the time of boil and retort heating in bag-made products. . On the other hand, if it exceeds 3, sufficient adhesion strength between the base material and the inorganic oxide deposited film cannot be obtained.

The water-soluble urethane resin (b) used in the water-soluble resin coating liquid is not particularly limited, but a dispersion type is preferable, and aliphatic or aromatic polyether urethane, aliphatic or aromatic polyester is used. Urethane, aliphatic or aromatic polycarbonate urethane, and the like. One or more of these may be used in combination. The water-soluble urethane resin (b) contributes to solvent resistance and has a solid content of 30% by weight.
It is preferably about 50% by weight. If the content is less than 30 wt%, not only the solvent resistance in printing on an inorganic oxide vapor-deposited film and the like is deteriorated, but also the effect of suppressing bleeding from the base material becomes weak. On the other hand, if it exceeds 50% by weight, not only sufficient gas barrier performance cannot be obtained, but also the resin coating film becomes hard.

The polyvinyl alcohol used for the water-soluble resin coating solution is not particularly limited, but the degree of polymerization is 30 in view of the viscosity of the coating solution and the oxygen barrier property of the coating film containing polyvinyl alcohol.
Those having 0 to 2000 and a saponification degree of 85 to 99.5 mol% are preferred. The solid content concentration in the above water-soluble resin coating solution is not particularly limited as long as it can be applied uniformly, but is usually 1 to 10% by weight, preferably 2 to 5% by weight. The water-soluble resin coating solution contains an antifoaming agent,
Various additives such as an emulsifier, an antistatic agent, an antiblocking agent, and a viscosity modifier may be appropriately added according to the purpose.

The application of the water-soluble resin coating solution to the substrate can be performed, for example, by a spray coating method, an air knife coating method,
Various coating methods using a metalling bar coating method, a Meyer bar coating method, a gravure roll coating method, a reverse roll coating method, a kiss roll coating method, or a combination thereof can be employed. When it is difficult to maintain an appropriate viscosity of the water-soluble resin coating solution or when it is difficult to apply the coating solution uniformly, the coating solution is used in an amount of, for example, 30 to 90.
It may be used by heating to ° C.

The coating thickness is usually 10 to 6 in terms of the WET film thickness.
It is selected so as to be usually 0.01 to 2 μm, preferably 0.03 to 1 μm when wound into a roll after transverse stretching and heat setting. 0.01μ
If it is less than m, the surface of the polypropylene-based resin having severe irregularities cannot be sufficiently smoothed, so that sufficient oxygen barrier properties cannot be obtained. Further, the effect of suppressing bleeding from the base material becomes weak. On the other hand, when the thickness is more than 2 μm, when the film is wound into a roll, not only blocking easily occurs, but also cost becomes high.

The stretched film before vapor deposition in the present invention is produced as follows. That is, the polypropylene resin,
A single layer or a multilayer is melt-extruded into a film, and the unstretched film is stretched usually 3 to 8 times in a longitudinal direction by utilizing a difference in peripheral speed of a roll group usually heated to 120 to 140, and then subjected to corona discharge treatment. Then, a water-soluble resin coating solution is applied to the corona-treated surface of the longitudinally stretched film, stretched usually 4 to 12 times in a transverse direction by a tenter, and heat-fixed as necessary. , Trimming both ends of the film,
It is manufactured by winding in a roll.

The amount of the above corona discharge treatment is usually 30 to
100 w · min / m ² . If it is less than 30 w · min / m ² , it is difficult to sufficiently modify the surface of the polypropylene resin, and sufficient adhesion strength with the water-soluble resin coating solution cannot be obtained. Conversely, if it exceeds 100 w · min / m ² , the discharge spark becomes large, and in the case where a whitening streak pattern is formed on the coating film, this causes uneven coating. Also,
The surface tension level of the corona discharge treated film surface is 3
5 dynes / cm or more, preferably 40 to 50 dynes / c
m is desirable.

The above-mentioned stretched film is preferably a biaxially stretched polypropylene film having a base material layer having a thickness of 10 to 100 μm and a thickness of at least one side of 0.01 to 2 μm.
This is a structure in which a uniaxially stretched film of a μm water-soluble resin coating liquid film is laminated. The film has good transparency, and the total light transmittance of the film is usually 85% or more, preferably 90% or more.

An inorganic oxide is deposited on the coated surface of the above stretched film. In this case, the inorganic oxide is a metal, a nonmetal, a submetal oxide, and as a specific example,
Aluminum oxide, zinc oxide, antimony oxide, indium oxide, calcium oxide, cadmium oxide, silver oxide,
Gold oxide, chromium oxide, silicon oxide, cobalt oxide, zirconium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, nickel oxide, platinum oxide, palladium oxide, bismuth oxide, magnesium oxide, manganese oxide, molybdenum oxide, oxidation Vanadium, barium oxide and the like are mentioned, but in combination with advanced oxygen gas barrier properties, water vapor barrier properties and transparency, and industrially inexpensive,
Silicon oxide and aluminum oxide are particularly preferred. Such silicon oxide and aluminum oxide may be used alone or as a mixture. The inorganic oxide may contain a trace amount of a metal, a nonmetal, a submetal, a hydroxide thereof, or carbon or fluorine for the purpose of improving flexibility.

For forming the deposited film, a vacuum deposition method is preferable from the viewpoint of the uniformity of the film and the adhesion to the substrate, and examples thereof include a resistance heating method, a high-frequency induction heating method, and an electron beam method. When silicon oxide is formed by a vacuum deposition method, SiO, SiO ₂ , a mixture thereof, and S
A mixture of i and SiO ₂ or the like is employed, and a reactive vapor deposition method performed while simultaneously supplying oxygen gas can also be employed. In addition, when aluminum oxide is formed by a vacuum evaporation method, aluminum oxide powder or solid is used as an evaporation source material, but a reactive evaporation method in which oxygen gas is introduced using aluminum metal and oxygen gas is not introduced is used. It is more preferable in that a non-crystalline and flexible aluminum oxide thin film layer can be formed.
The thickness of the deposited film is not particularly limited, and varies depending on the type of the inorganic oxide and the like. However, from the viewpoints of oxygen gas barrier property and water vapor barrier property, transparency, cost, and the like, it is usually 50 to 2,000 angstroms, preferably 100 to 500 angstroms. It is.

The gas barrier film obtained by the production method of the present invention may be used as it is depending on the intended use, or a heat sealing layer or a protective layer may be provided on the deposited film. The heat seal layer is not particularly limited, and is usually non-stretched polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, or ethylene-vinyl acetate copolymer, ethylene-acrylic acid Examples include an ethylene ionomer such as a copolymer. The heat seal layer is usually provided by a dry lamination method or an extrusion method. The thickness is usually from 20 to 100 μm, preferably from 40 to 80 μm.
The protective layer is made of polyester, nylon, ethylene-
It is provided by laminating a film such as a vinyl alcohol copolymer, or by coating a heat-resistant epoxy resin, melamine resin, urethane resin, polyester resin, or the like.

[0024]

EXAMPLES The present invention will be described below in detail with reference to examples, but the scope of the present invention is not particularly limited thereby. The evaluation of the film obtained in the following examples was performed by the following method. In addition, what is referred to as a laminate film is that a non-stretched polypropylene film having a thickness of 50 μm is dry-laminated using a two-component curable polyurethane-based adhesive on the inorganic oxide thin film surface of the gas barrier film of the present invention, and is heated at 40 ° C. Aged for 3 days, it means a resin molded article provided with a gas barrier property and provided with a heat seal layer.

<MFR [g / 10 min]> JIS K-6
Measurement was performed at 758 with a load of 2160 g and a measurement temperature of 190 ° C. <Thickness of Water-Soluble Resin Coating Layer [μm]> The cross section of the wound stretched film was observed and measured with a transmission electron microscope (H-600 manufactured by Hitachi, Ltd.). <Thickness of deposited film [angstrom]> The thickness of the deposited film as Si was measured using a fluorescent X-ray apparatus manufactured by Rigaku Corporation. <Total light transmittance [%] and haze> The haze meter NDH300A manufactured by Nippon Denshoku Industries was measured. <Yellowness> Measured using a color difference meter Z- # 80 manufactured by Nippon Denshoku Industries. <Solvent resistance> Using a cotton swab impregnated with ethyl acetate, the surface of the inorganic oxide thin film was lightly rubbed five times in a predetermined direction from above, and the peeling state of the inorganic oxide thin film was measured with an optical microscope (200).
X) and evaluated according to the following criteria.・: The rubbed portion did not peel off. Δ: The rubbed part is slightly peeled off. X: The rubbed part is peeled off.

<Oxygen permeability [cc / m ² · 24h · atm]> OX- manufactured by Modern Control Co., Ltd.
The measurement was performed using a TRAN2 / 20 type oxygen permeability measuring device under the conditions of a temperature of 25 ° C. and a relative humidity of 80%, and a condition of a temperature of 25 ° C. and a relative humidity of 90%. <Water vapor transmission rate (moisture ^{permeability) [g / m 2 · 24h} ]> surface area of the heat seal layer in the inner surface of the laminate film is about 10
After making a bag of 0 cm ² and adding an appropriate amount of calcium chloride,
Sealed. This was left in an atmosphere of 40 ° C. and 90% RH for 7 days, and the water vapor permeability was determined from the weight increase. <Lamination strength [g / 15mm]> Using a strip-shaped test piece of 15 mm in width and 10 cm in length cut out from a laminate film, using an Autograph AG-I type of Shimadzu Corporation at a load cell of 5 kg and a test speed of 300 mm / min. 1
It was determined from the 80 ° peel strength.

Example 1 and Comparative Example 1 Novatec PP FL6CK (MFR 2.4, melting point 161) manufactured by Nippon Polychem Co., Ltd. as a polypropylene resin
C.), extruded at a temperature of 220 ° C. in the extruder, extruded from a T-die into a sheet, and brought into close contact with a 30 ° C. cast roll to obtain an unstretched sheet. Next, using a longitudinal stretching machine composed of a group of heating rolls having different peripheral speeds, the unstretched sheet is stretched in multiple stages at a temperature of 130 ° C. so as to finally become 5 times, and then the surface side to be coated is 90 w · min. / M ²
The corona discharge treatment was performed under the following conditions. Next, a water-soluble resin coating solution (solid content concentration: about 2.5 wt%) adjusted to have a solid content weight ratio of Example 1 and Comparative Example 1 in Table 1 was wet-coated with a metalling bar coater. About 15μ
m, and then introduced into a tenter oven at 150 ° C., stretched 10 times in the transverse direction, and heat-set at 158 ° C. to obtain a coating film having a thickness of 20 μm. Each of the coating layers had a thickness of about 0.04 μm.

The water-soluble resin coating surface of the respective film, 1 × and 10 ^-5 4 × vacuum of 10 ^-5 Torr by introducing oxygen after the high vacuum Torr, purity 99 with an electron beam heating method 9.9% of silicon monoxide (SiO) was heated and evaporated to obtain a vapor-deposited film laminated stretched film. With the obtained film as it was, the thickness of the deposited film, the total light transmittance, the haze and the yellowness were measured, and the solvent resistance was evaluated. Next, after forming a laminated film, the oxygen transmission rate, the water vapor transmission rate, and the lamination strength were measured. The results are shown in Example 1 and Comparative Example 1 in Table-2. With the composition of Comparative Example 1, the fundamental oxygen barrier performance is not sufficient.

Example 2 and Comparative Example 2 In Example 1, the weight ratio of the solid content of the water-soluble resin coating solution was changed to the composition shown in Example 2 and Comparative Example 2 in Table 1; 8 × on the coating surface
After a high vacuum of 10 ^-5 Torr, oxygen is introduced to 3 × 10 ^-4
A vacuum-stretched laminated film was obtained in the same manner as in Example 1 except that aluminum metal having a purity of 99.99% was heated and evaporated under a vacuum of Torr. The measurement results of each physical property are shown in Example 2 and Comparative Example 2 in Table-2. In the composition of Comparative Example 2, the oxygen barrier performance on the high humidity side (25 ° C. × 90% RH) is not preferable.

Example 3 and Comparative Example 3 "Novatech PP FL6CK" (MFR2.4, melting point 161) manufactured by Nippon Polychem Co., Ltd. as a polypropylene resin.
° C) and maleic anhydride-grafted polypropylene (MF
R2.3; maleic anhydride grafting ratio 0.05% by weight; melting point 138 ° C.)
Melted at 20 ° C, layered in feedblock,
-An unstretched sheet was prepared by extrusion from a die (the thickness of the maleic anhydride-grafted polypropylene layer was 13
%), And the solid content weight ratio of the water-soluble resin coating solution was changed to the compositions shown in Example 3 and Comparative Example 3 in Table 1 in the same manner as in Example 1. A stretched film was obtained. The measurement results of each physical property are shown in Example 3 and Comparative Example 3 in Table 2. The composition of Comparative Example 3 has poor solvent resistance.

Example 4 and Comparative Example 4 In Example 2, the solid content weight ratio of the water-soluble resin coating solution was changed to the composition shown in Example 4 and Comparative Example 4 in Table 1, and Solid content concentration about 5wt
% (The thickness of each coating layer was about 0.08
μm) in the same manner as in Example 2 to obtain a vapor-deposited laminated film. The measurement results of each property are shown in Example 4 and Comparative Example 4 in Table-2. With the composition of Comparative Example 4, none of the oxygen barrier properties, solvent resistance, and lamination strength are sufficient.

Comparative Example 5 A laminated and stretched film was obtained in the same manner as in Example 1 except that the water-soluble resin coating solution was not coated. The measurement results of each physical property are shown in Comparative Example 5 of Table-2. In this configuration, oxygen barrier properties, solvent resistance,
Neither lamination strength is preferred. Comparative Example 6 In Example 1, a coating film before vapor deposition was used as a sample. The measurement results of each physical property are shown in Comparative Example 6 of Table-2. In this configuration, the oxygen barrier property is not particularly preferable.

[0033]

[Table 1]

The coating resins (a) in Table 1
(B) and (c) are as follows. <Water-soluble acrylic resin (a)> Acrylic 1: "Julima FC-80" manufactured by Nippon Pure Chemical Industries, Ltd.
(The blending amount is calculated assuming a solid concentration of 30%) <Water-soluble urethane resin (b)> Urethane 1: "NeoRez R-960" manufactured by Zeneca Corporation.
3 "(The blending amount is calculated assuming a solid content concentration of 34%) Urethane 2:" Hydran manufactured by Dainippon Ink and Chemicals, Inc.
AP-30 "(the blending amount is calculated on the assumption that the solid content concentration is 20%) <Polyvinyl alcohol (c)> PVA1: Nippon Synthetic Chemical Industry Co., Ltd." Gohsenol N-3 "
00 (polymerization degree 1650-1700 saponification degree 98-99m
ol%) ”PVA2:“ Gohsenol GM- ”manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
14 (degree of polymerization: 1650 to 1700, degree of saponification: 86.5 to 8)
9mol%)] For the method of dissolving PVA1 and PVA2 (granular) in water, refer to the catalog of the same product and add (a) to the aqueous solution in which (c) is dissolved.
The solution and the solution (b) were added to prepare a water-soluble resin coating solution.

[0035]

[Table 2]

[0036]

The gas barrier film obtained by the present invention, that is, the molded article of a polypropylene resin on which an inorganic oxide thin film is deposited, has excellent gas barrier properties not only on the low humidity side but also on the high humidity side. Since the metal oxide thin film does not peel off at the time of secondary processing or use and the gas barrier property does not deteriorate, and at the same time it has excellent transparency and solvent resistance,
As an inexpensive packaging material that replaces VDC coat OPP, it can be widely used as a resin molded product for packaging used to protect foods, industrial products, pharmaceuticals, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C23C 14/10 C23C 14/10 14/20 14/20 A B29K 23:00 B29K 23:00 B29L 7:00 B29L 7:00 9:00 9:00 C08L 23:10 C08L 23:10 F term (reference) 4F006 AA12 AB20 AB24 AB37 AB74 BA05 CA07 DA01 4F073 AA01 BA08 BB01 CA21 4F100 AA01C AA20 AK01D AK07A AK21B AK25B AK51BA03A03BA05BA05BA03 BA10C BA25 EH17 EH172 EH46 EH462 EH66 EH662 EJ37 EJ372 EJ38 EJ382 EJ55 EJ552 GB23 GB66 JB07 JB09B JD02 JD03 JL13D JN01 4F210 AA11 AA21 AA31 AG01 AG03 QC06 QD08 QD10 QG01 QG01 QG01 QG01 A44

Claims (2)

[Claims] An unstretched film obtained by melt-extruding a polypropylene resin is stretched in the machine direction, subjected to corona discharge treatment, and then a water-soluble acrylic resin (a), After applying a water-soluble resin coating solution composed of a water-soluble urethane resin (b) and polyvinyl alcohol (c) and having a weight ratio of a solid content that satisfies the following formulas (1) to (3), and then stretching in the lateral direction And forming a vapor-deposited film of an inorganic oxide on the coating surface. [Formula 1] 50 wt% ≦ (a) + (c) ≦ 70 wt% (1) 30 wt% ≦ (b) ≦ 50 wt% (2) 1 ≦ (a) / (c) ≦ 3 (3) 2. A method for producing a gas-barrier laminated film, comprising a heat-sealing layer provided on the gas-barrier film of claim 1.