JP2001009976A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminated film not only good in oxygen barrier properties or the humidity dependence of oxygen barrier properties but also excellent in heating and sterilizing treatment properties. SOLUTION: A laminated film is obtained by laminating an A-layer and a B-layer both of which comprise a thermoplastic resin film to a C-layer comprising a polymeric gas barrier layer composed of either one of a mixture of a partially hydrolyzed polycondensate of at least one alkoxide selected from metal alkoxide and silicon alkoxide and a water soluble polymer, a reaction product of the partially hydrolyzed polycondensate and the water soluble polymer and a mixture of the partially hydrolyzed polycondensate, the water soluble polymer and the reaction product and the A-layer and the B-layer are different in moisture permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film suitable as a packaging film, and more particularly, to a laminated film suitable as a gas barrier film for packaging of water-based products or heat sterilization treatment.

[0002]

2. Description of the Related Art Thermoplastic resin films such as polypropylene films and PET films have good workability, excellent mechanical strength, transparency, and secondary workability such as bag making.
It is widely used as a packaging film.

Further, in order to impart functions such as gas barrier properties (particularly oxygen barrier properties), a water-soluble polymer such as a vinylidene chloride resin or a polyvinyl alcohol resin is coated on the surface of the thermoplastic resin film. Lamination has been done. However, although vinylidene chloride-based resins have excellent gas barrier properties, they are disadvantageous in incineration and disposal because they are chlorine-based resins.Water-soluble polymers such as polyvinyl alcohol-based resins have excellent oxygen barrier properties in the dry state. However, there is a known problem that the oxygen barrier property decreases as the humidity increases.

As means for solving the above problem, Japanese Patent Laid-Open No.
-345841, JP-A-8-99390,
JP-A-9-278968, JP-A-9-29125
No. 1 discloses a laminated film of a thermoplastic resin and a composite polymer layer of an inorganic substance and a polyvinyl alcohol-based resin obtained by a sol-gel method polycondensation.

On the other hand, food packaging such as pickles and prepared foods is required to be suitable for heat sterilization such as boiling sterilization in addition to a gas barrier function under high humidity.

[0006] However, although the laminated film disclosed in the above-mentioned publication has a relatively improving effect on the oxygen barrier property under high humidity, there is room for improvement on heat sterilization suitability.

On the other hand, in order to achieve both heat sterilization suitability and oxygen barrier properties, Japanese Patent Application Laid-Open No. 7-251874 discloses a laminated film having a composition layer comprising a layered inorganic compound having a specific aspect ratio and a resin. Have been.

However, the laminated film disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-251874 is not yet sufficient with respect to the oxygen barrier properties of the gas barrier layer itself under high humidity, and is not suitable for heat sterilization treatment of the entire laminated film. There was still room for improvement.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laminated film having excellent oxygen barrier properties under high humidity and excellent heat sterilization suitability.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object. As a result, a layer made of a thermoplastic resin film having different moisture permeability,
It has been found that the above problem can be solved by laminating a specific polymer gas barrier layer, and the present invention has been completed.

That is, the present invention relates to an A layer and a B layer comprising a thermoplastic resin film, and (1) a partially hydrolyzed polycondensate of at least one alkoxide selected from the group consisting of metal alkoxides and silicon alkoxides. A mixture with a water-soluble polymer, (2) a reaction product of the partially hydrolyzed polycondensate and a water-soluble polymer, and (3) a reaction product of the partially hydrolyzed polycondensate, a water-soluble polymer and the reaction product. A laminated film formed by laminating a C layer composed of a polymer gas barrier layer composed of any one of the above mixtures, wherein the A layer and the B layer are layers having different moisture permeability. It is.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated film of the present invention is a laminated film comprising at least three layers: an A layer and a B layer made of a thermoplastic resin having different moisture permeability, and a C layer made of the above-mentioned polymer gas barrier layer. There is no particular limitation, and the layer configuration may be selected in consideration of the purpose and application.

For example, in the above three-layer structure, if layer A is made of a thermoplastic resin having a higher moisture permeability than layer B, layer A / layer B / C or layer A / C / The layer configuration of the B layer is preferable. Among them, the layer configuration of the A layer / C layer / B layer is preferable in consideration of suitability for heat sterilization treatment and the like.

Further, other layers may be provided in the middle and / or the outer layer of each layer.

In the present invention, the thermoplastic resin film used for the layer A and the layer B is not particularly limited, and a known single-layer or multilayer film may be selected so as to have different moisture permeability. Further, as the thermoplastic resin film, a film mainly having excellent mechanical properties and secondary workability of the film is preferable.

The thermoplastic resin which is the raw material resin for the film includes olefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polybutylene terephthalate and polyethylene-2,6-naphthalate, nylon 6 and nylon 1.
Polyamide resin such as 2, polyvinyl chloride, ethylene-vinyl acetate copolymer or saponified product thereof, polystyrene,
Examples include polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamideimide, polyacrylonitrile, polyvinyl alcohol, and the like, and copolymers thereof.

Of these, the film constituting the layer A is preferably a film made of a polyolefin resin, polyethylene terephthalate, or a polyamide resin.

As the polyolefin resin constituting the layer A, a known polyolefin resin such as a homo- or copolymer containing an α-olefin is used. Specifically, α-olefin homopolymers such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene, and random or block copolymers of two or more α-olefins described above. Polymers, one or more random or block copolymers of ethylene with vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ionomer resins, and mixtures of these polymers, etc. .

Of these, considering the mechanical strength, surface gloss, moisture resistance, heat resistance, transparency, etc. of the layer A, propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene-butene A polypropylene resin such as an original copolymer is preferred, and a propylene homopolymer is more preferred.

The measured value of the peak top in the differential scanning calorimetry (hereinafter, referred to as DSC) of the polypropylene resin is the heat resistance of the film (generally, the heat resistance when a high-temperature seal bar comes into contact with the film during heat sealing). Considering
130 to 165 ° C., preferably 135 to 16 ° C.
The temperature is more preferably 5 ° C. In addition, the melt flow rate (hereinafter, referred to as MFR) is determined in consideration of extrudability.
It is preferably 0.1 to 10 g / 10 minutes.

Shows the crystallinity of the polypropylene resin
^The isotactic pentad fraction by ¹³ C-NMR is 0.8 in consideration of heat resistance, moisture resistance and stretchability.
50 to 0.995, preferably 0.900 to 0.900.
More preferably, it is 0.990. The above isotactic pentad fraction was obtained from A.I. Zamberg (A.
Zambelli et al., Macromolecules, 13 , 267 (1
980), which is a fraction in which five propylene units quantified based on the peak assignment of the 13C-NMR spectrum published in a continuous manner have the same configuration.

Further, in the polypropylene resin,
A hydrocarbon resin such as a petroleum resin or a terpene resin may be mixed for the purpose of controlling the moisture permeability.

In the present invention, the film constituting the layer B may be selected from the thermoplastic resins mentioned above, which have a lower moisture permeability than the layer A, such as polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate and polybutylene terephthalate. A film made of a polyester resin is preferable, and among them, a film made of a polyolefin resin having a lower moisture permeability than the layer A is more preferable.

Examples of the polyolefin resin constituting the layer B include known polyolefin resins such as α-olefin homopolymers and copolymers containing α-olefins. For example, α-olefin homopolymers such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, random or block copolymers of two or more α-olefins, ethylene From one or more random or block copolymers of vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, and methyl methacrylate, or an ionomer resin, and a mixture of these polymers. A polymer having low moisture permeability may be selected.

As the method for producing the polyolefin resin, known methods can be used without any limitation.
A method of polymerizing the above-mentioned monomer using a known polymerization catalyst for polyolefin such as iCl ₃ -supported TiCl _{3 or} a metallocene-based catalyst may be used. Further, after polymerization using the above catalyst, a method of decomposing with a peroxide or the like may be performed.

As a method for producing the thermoplastic resin film used in the present invention, known methods can be used without limitation. Specific examples include a T-die method and a tubular method in which a thermoplastic resin is melt-extruded and then cooled to obtain an unstretched film. In consideration of mechanical properties and the like, a method of further stretching to form a stretched film is preferable. As the stretching method, a vertical or horizontal uniaxial stretching method, a vertical and horizontal sequential biaxial stretching method,
Examples thereof include a simultaneous biaxial stretching method, a rolling method, and a method of successively stretching a sheet formed by calendering in at least one direction. Among these stretching methods, in consideration of thickness / thinness accuracy, mechanical properties, and the like, a longitudinal and transverse sequential biaxial stretching method and a tenter method simultaneous biaxial stretching method are preferable.

Among them, the thermoplastic resin film used for the layer A includes mechanical strength, surface gloss,
In consideration of heat resistance, transparency and the like, a stretched film is preferable, and a biaxially stretched film is more preferable. The thickness of the thermoplastic resin film used for the layer A is generally appropriately selected from the range of 1 to 500 μm, and is 5 in consideration of moisture permeability, stretch processability, bag making process, and the like.
It is preferably from 60 to 60 μm, and more preferably from 10 to 40 μm.

On the other hand, the thermoplastic resin film used for the layer B is preferably a non-stretched film in consideration of the heat sealing property and moisture permeability as the inner layer. The thickness of the thermoplastic resin film used for the B layer is generally appropriately selected from a range of 1 to 500 μm, and is 5 to 100 in consideration of heat sealability, moisture permeability, bag-making workability, and the like.
μm, more preferably 10 to 80 μm.

In the present invention, it is necessary that the moisture permeability of the layer A and the layer B made of a thermoplastic resin be different. As described above, when the layer A is a layer made of a thermoplastic resin having a higher moisture permeability than the layer B, the moisture permeability ratio of the two layers is (water vapor permeability of the layer A / water vapor permeability of the layer B). Is preferably 1.2 or more, and more preferably 1.5 or more. If the moisture permeability of the A layer and the moisture permeability of the B layer are equal, the humidity environment of the barrier layer is likely to be maintained at a high humidity at the time of packaging of water products or after the heat sterilization treatment, which is not preferable because the gas barrier property is reduced.

The thermoplastic resin film used in the present invention may contain, if necessary, an antistatic agent, an antifogging agent, an antiblocking agent, an antioxidant, a light stabilizer, a crystal nucleating agent, a lubricant, an ultraviolet absorber, a slip. Known additives such as a surfactant for the purpose of imparting properties and imparting an anti-blocking property may be added to such an extent that the effects of the present invention are not impaired.

The thermoplastic resin film used in the present invention is preferably transparent, considering that it is suitably used for packaging, particularly as a gas barrier film. Specifically, the haze value is preferably 15% or less, more preferably 10% or less.

The thermoplastic resin film used in the present invention may be subjected to a known film surface treatment in order to improve the adhesive strength and the like. Specifically, corona discharge treatment,
One or more kinds of treatments such as a plasma treatment, a flame plasma treatment, an electron beam irradiation treatment, and an ultraviolet irradiation treatment are exemplified.

The C layer used in the present invention includes: (1) a mixture of a partially hydrolyzed polycondensate of at least one alkoxide selected from the group consisting of metal alkoxides and silicon alkoxides, and a water-soluble polymer. (2) A reaction product of the partially hydrolyzed polycondensate and a water-soluble polymer. (3) a mixture with the partially hydrolyzed polycondensate, the water-soluble polymer and the reaction product. And a composite polymer layer composed of any one of the above.

In the present invention, the water-soluble polymer is a polymer which can be completely dissolved or finely dispersed in water at normal temperature.
Specific examples include polyvinyl alcohol and derivatives thereof; polyalcohols obtained by reducing a polyketone composed of a carbon monoxide-ethylene copolymer; cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose; oxidized starch, etherified starch, Starches such as dextrin; water-soluble vinyl copolymers such as polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, or esters, salts and copolymers thereof; or carboxyl groups and silyl groups of these various polymers And the like.

Of these, polyvinyl alcohol polymers and derivatives thereof are preferred.
5 mol% or more of polyvinyl alcohol, 40% of all hydroxyl groups
More preferred is polyvinyl alcohol in which less than mol% is acetalized, and copolymerized polyvinyl alcohol such as ethylene-vinyl alcohol copolymer (hereinafter referred to as EvOH) in which the vinyl alcohol unit is more than 60 mol%.

The degree of polymerization of the above-mentioned polyvinyl alcohol and its derivative is 1 in consideration of gas barrier properties and processability.
It is preferably from 00 to 5,000, and from 500 to 3,
000 is more preferable.

On the other hand, the metal alkoxide and the silicon alkoxide used in forming the composite polymer layer are polycondensed by a sol-gel method so that an oxide polymer such as a metal oxide compound polymer or a silicon oxide compound polymer can be formed. It is not particularly limited. In particular,
Silicon alkoxides capable of forming silicon oxide such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, isopropyltrimethoxysilane, butyltrimethoxysilane; tetramethoxytitanium, tetraethoxytitanium, methyltrimethoxytitanium; Titanium alkoxides such as tetrabutoxytitanium, tetraisopropoxytitanium, and methyltriisopropoxytitanium that can form titanium oxide; tetramethoxyzirconium, tetraethoxyzirconium, tetrabutoxyzirconium, methyltrimethoxyzirconium, methyltriethoxyzirconium, methyltriethoxyzirconium Zirconium oxide capable of forming zirconium oxide such as methyltriisopropoxyzirconium; Aluminum alkoxides capable of forming aluminum oxide, such as toxium aluminum, triethoxy aluminum, triisopropoxy aluminum, and methyldiisopropoxy aluminum; magnesium alkoxides capable of forming magnesium oxide, such as tetramethoxy magnesium, tetraethoxy magnesium, tetra isopropoxy magnesium; Sidoxymethyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltributoxysilane,
(3,4-epoxycyclohexyl) methyltripropoxysilane, 2- (3,4-epoxycyclohexyl)
Silicon alkoxide having an epoxy group such as ethyltrimethoxysilane, 3- (3,4-epoxycyclohexyl) propyltrimethoxysilane; aminomethyltriethoxysilane, 2-aminoethyltrimethoxysilane,
-Aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminomethylaminomethyltrimethoxysilane, N-aminomethyl-3-aminopropyltrimethoxysilane, N- (2 Silicon alkoxide having an amino group such as -aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; vinyltrimethoxysilane, vinyltriacetoxysilane, N- β-
(N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane or a silicon alkoxide having a vinyl group such as a hydrochloride thereof; or a mixture of two or more thereof.

Among the above metal alkoxides and silicon alkoxides, particularly preferred ones are tetramethoxysilane, tetraethoxysilane, tetramethoxytitanium, tetraethoxytitanium, tetrabutoxytitanium, tetraisopropoxytitanium, tetramethoxyzirconium, tetraethoxyzirconium , Tetrabutoxyzirconium, trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, glycidoxymethyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycid Xypropyl tributoxy silane.

In the present invention, the composition for forming the composite polymer layer can be obtained by appropriately selecting and mixing the water-soluble polymer and the metal alkoxide and / or silicon alkoxide. in this case,
The mixing ratio of the water-soluble polymer and the metal alkoxide and / or silicon alkoxide is determined by the mixing ratio of the water-soluble polymer and the metal oxide compound polymer and / or the silicon oxide compound polymer in the formed composite polymer (water-soluble Polymer / metal oxide compound and / or silicon oxide compound polymer wt% / wt%)
It is preferable to determine the ratio so as to be / 90 to 80/20 in consideration of the ratio in order to exhibit good gas barrier properties. The above ratio in the composite polymer is particularly preferably 20/80 to 70, considering gas barrier properties and humidity dependency.
/ 30 is more preferable.

As long as the composition for forming the above-mentioned composite polymer layer does not impair the good gas barrier properties, components other than those described above, for example, inorganic compounds such as inorganic fine particles and inorganic layered compounds, and a crosslinking agent may be used. May be added.
Specific examples of the inorganic compound include inorganic fine particles such as kaolin, calcium carbonate, barium sulfate, calcium fluoride, lithium fluoride, and calcium phosphate, montmorillonite, kaolinite, halloysite, vermiculite, dickite, nacrite, antigolite, and virophyte. Examples include inorganic layered compounds such as light, hectorite, beidellite, margarite, talc, tetrasilyl mica, muscovite, phlogopite, and chlorite. Specific examples of the crosslinking agent include a urethane-based crosslinking agent, an isocyanate-based crosslinking agent, a melamine-based crosslinking agent, and an epoxy-based crosslinking agent.

The composition for forming the composite polymer layer may be in a state where the above components are dispersed and mixed with each other, or may be in a crosslinked state.

The thickness of the layer C is preferably from 0.1 to 10 μm, more preferably from 0.3 to 5 μm, in consideration of gas barrier properties, bag-making workability, economy and the like.

In the present invention, the method for forming the polymer gas barrier layer is not particularly limited, and any known forming method may be employed without limitation.

For example, a coating solution comprising a water-soluble polymer and a composition containing the above-mentioned metal alkoxide and / or silicon alkoxide is coated on the above-mentioned layer A or layer B by a known method, and dried and cured. The method is generally adopted.

The composition of the above coating solution should be
On the A layer or the B layer, the metal alkoxide and / or
Alternatively, there is no particular limitation as long as a polycondensate of silicon alkoxide can be formed. For example, a composition composed of a liquid material in which a water-soluble polymer and a metal alkoxide and / or a silicon alkoxide are uniformly dissolved or dispersed in a solvent, a composition in which a hydrolyzing agent is added as required, and a metal After adding an alkoxide and / or a silicon alkoxide, if necessary, a hydrolyzing agent to prepare an oxide polymer that is a polycondensate in advance, and then uniformly dissolving or dispersing in a solvent together with a water-soluble polymer. No.

As the above-mentioned hydrolyzing agent, known ones are used without any particular limitation. Specifically, inorganic acids such as hydrochloric acid,
Examples include an organic acid such as acetic acid, or an alkaline aqueous solution such as sodium hydroxide, ammonia, and an organic amine compound. However, even water alone can exert its function as a hydrolyzing agent.

As a solvent for dissolving or dispersing the water-soluble polymer, water or a mixed solvent of water / lower alcohol is preferable. In consideration of adhesion and productivity, it is more preferable to use a mixed solvent of water / lower alcohol. preferable. The lower alcohol is preferably an alcohol having 1 to 3 carbon atoms, specifically, methanol, ethanol, n-propyl alcohol, or isopropyl alcohol. The mixing ratio of water / alcohol is 99/1 to 1 by weight.
It is appropriately selected from the range of 20/80.

Further, in order to enhance the suitability for coating a layer made of a thermoplastic resin film, other water-soluble organic compounds may be added to the above-mentioned coating liquid as long as the stability of the coating liquid is not impaired. . Specifically, in addition to the lower alcohol used as a solvent, ethylene glycol,
Glycols such as propylene glycol; glycol derivatives such as methyl cellosolve, ethyl cellosolve and n-butyl cellosolve; polyhydric alcohols such as glycerin and waxes; ethers such as dioxane and trioxane;
Esters such as ethyl acetate; ketones such as methyl ethyl ketone; aqueous anchor coating agents such as aqueous isocyanate, polyethyleneimine and epoxy resin.

The pH of these coating solutions is preferably 2 to 11 in consideration of the stability of the coating solution.

As a method of coating the above coating solution,
Although not particularly limited, a solution or solvent dispersion coating method capable of high-speed thin film coating is preferable in the practice of the present invention, and is suitably employed. When these coating methods are specifically exemplified, a coating solution dissolved or dispersed in various solvents is coated with a gravure coat, a reverse coat, a spray coat, a kiss coat, a die coat, a metaling bar coat, a gravure coat in combination with a chamber doctor, and a curtain coat. The method of coating the layer A or the layer B is preferable.

The above-mentioned coating may be performed at any stage, for example, a method of coating on a vertically uniaxially stretched sheet and then performing transverse stretching, or a method of performing in-line coating such as successively coating after biaxially stretching. Or an off-line coating method. Of these, off-line coating is preferable in consideration of easy control of drying and curing conditions and small turn.

As a method for drying and curing the coating solution after coating on the thermoplastic resin film, a known drying and curing method can be used without any particular limitation. Specific examples include one or more of a hot roll contact method, a heat medium (air, oil, etc.) contact method, an infrared heating method, a microwave heating method, and the like. Among these, the heating air contact method and the infrared heating method are preferable in consideration of the finish such as the appearance of the obtained laminated film and the drying efficiency.

The drying and curing temperature is preferably 80 ° C. or higher in consideration of barrier properties and drying efficiency.
It is more preferable that the temperature is 100 ° C. or higher. When the drying and curing temperature is lower than 80 ° C., the oxygen barrier property and the moisture resistance are undesirably reduced. The drying and curing temperature is preferably equal to or lower than the melting point of the thermoplastic resin used. If the drying and curing temperature is higher than the melting point of the thermoplastic resin to be used, it is not preferable because the resulting film suffers from appearance defects such as curling, wrinkling, and melting whitening, which are considered to be due to thermal shrinkage.

The drying time is preferably 5 seconds to 10 minutes in consideration of barrier properties and drying efficiency.
More preferably, it is 0 second to 5 minutes.

Before and after the above-mentioned drying and curing, if necessary, irradiation with high energy rays such as ultraviolet rays, X-rays and electron beams may be performed.

In the method for producing a laminated film of the present invention, the composite polymer layer is laminated on the layer A or the layer B as described above, and then laminated so that the other thermoplastic resin film is required. It should be done.

The laminated film of the present invention is not particularly limited as long as it has the above-mentioned layer constitution. For example, an intermediate layer between the above-mentioned thermoplastic resin film layer and the polymer gas barrier layer is provided as long as the effects of the present invention are not impaired. Or, on the outer surface of a layer made of a thermoplastic resin film, a coating layer or a printing layer of acrylic, polyol polyester, polyurethane, room temperature glass or the like, another plastic film layer, metal and / or metal oxide, etc. It may include an evaporation layer, a metal foil, and the like.

The use of the laminated film of the present invention is not particularly limited, but it is a film for food packaging such as a gas barrier (oxygen barrier, nitrogen barrier, carbon dioxide gas barrier, etc.) film, particularly for the packaging of water-based foods, boil and retort sterilization treatment. It is suitable as a packaging film. The packaged material is not particularly limited, but specifically, pickles, prepared dishes, boiled tsukudani, konjac, miso, kamaboko, chikuwa, processed fishery products, hamburger, wiener, sausage, ham, other processed meat products, cheese, butter , Cut rice cake, tororo kelp, curry,
Foods such as stew, packed rice, and the like are included. Furthermore, medical, electronic, and agricultural chemicals, pharmaceuticals, fertilizers, precision materials, etc.
It may be used for industrial packaging applications such as chemical and mechanical applications.

When used for the above-mentioned packaging applications, the layer configuration may be appropriately selected according to the application to be used. For example, when the layer A is a layer made of a thermoplastic resin having higher moisture permeability than the layer B, In the layer structure of layer A / layer C / layer B, when used for packaging of water-based foods, boil, and retort sterilization packaging film, the layer is packed such that layer A is an outer layer and layer B is an inner layer. Is preferred.

[0060]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, about the resin and film physical property in the following example and the comparative example, it performed by the following method.

(1) Measurement of main peak of raw resin by DSC About 5 to 6 mg of a sample was weighed, sealed in an aluminum pan, and heated from a room temperature to 235 ° C. in a nitrogen flow of 20 ml / min by a differential calorimeter. Warm, hold at this temperature for 10 minutes, then cool to room temperature at 10 ° C / min. Thereafter, a main peak was measured from a melting curve obtained at a heating rate of 10 ° C./min.

(2) MFR Measured according to JIS K7210.

(3) Pentad fraction (mmmm value) and copolymer composition Measured under the following conditions using JNM-GSX-270 (13C-nuclear resonance frequency: 67.8 MHz) manufactured by JEOL. Measurement mode: 1H-complete decoupling Pulse width: 7.0 microseconds (C45 degree) Pulse repetition time: 3 seconds Integration frequency: 10000 times Solvent: Mixed solvent of ortho-dichlorobenzene / deuterated benzene (90/10 volume%) Sample concentration: 120 mg / 2.5 ml solvent Measurement temperature: 120 ° C. In this case, the mmmm pentad fraction is 13 C-NMR
It was determined by measuring the splitting peak in the methyl group region of the spectrum. Also, the assignment of the peak in the methyl group region is
A. Zambellietal [Macromolec
ules 13, 267 (1980)].

(4) Transparency (haze) Measured according to JIS K6714.

(5) Oxygen Barrier Property a) Method (Measurement of Raw Coated Film) Measured using an oxygen transmittance measuring device manufactured by mocon in accordance with JIS K7126 B method. Measurement conditions are 25
C., RH 90%. b) Method (Measurement of Laminated Film) The measurement was carried out according to JIS K7126 B method using an oxygen permeability measuring device manufactured by mocon. Measurement conditions are 25
C., RH 60% on the outer layer side and 100% RH on the inner layer side.

(6) Moisture Permeability According to the JIS K7129B method, the moisture permeability was measured in an atmosphere of 40 ° C. and RH 90% using a moisture permeability measuring device manufactured by mocon.

(7) Coating Using a test coater manufactured by Akatsuki Machinery Co., a base film having a width of 30 cm was coated and dried and cured under the following conditions. Drying method: Guide roll arch type hot air jet nozzle spraying method Coating method: Gravure method Drying furnace length; 6 m Coating speed; 18 m / min Setting temperature; 120 ° C. Drying time; 20 seconds

[Preparation of Coating Solution A] 30 parts by weight of tetraethoxysilane, 20 parts by weight of ethanol, 1 part by weight of 2N hydrochloric acid and 4 parts by weight of water were mixed and stirred at room temperature for 1 hour. Next, 3 parts by weight of γ-glycidoxytrimethoxysilane, 40 parts by weight of 20 L of Soarnol (ethylene-vinyl alcohol water / IPA solution manufactured by Nippon Gosei Kagaku), and 0.15 parts by weight of N, N-dimethylbenzylamine were added and stirred. Then, a coating liquid A was obtained. [Preparation of coating liquid B] Polyvinyl alcohol (PVA117H manufactured by Kuraray Co., Ltd.) was dissolved in ion-exchanged water so as to be 4% by weight. This solution was ultrasonically dispersed with natural montmorillonite (Kunimine Kogyo Co., Ltd., Kunipia F) to a concentration of 2% by weight to obtain a coating liquid B.

Example 1 Propylene homopolymer (MFR: 2, melting point: 155 ° C.)
20 μm corona treatment (wetting index: 40)
Dyne) biaxially oriented polypropylene film (moisture permeability 7.
5 g / m ² · day) was used as the base film. An anchor coat having a dry film thickness of 1 μm (manufactured by Toyo Morton Co .; main agent AD335AE / hardener C)
(AT-10 100 parts by weight / 10 parts by weight), and then the coating liquid A was coated so as to have a dry film thickness of 4 μm and then dried and cured to obtain a coated film raw material. A dry laminating agent (manufactured by Toyo Morton Co., Ltd .; base agent TM329 / hardener CAT-8B 100)
Parts by weight / 100 parts by weight) and dried to a dry film thickness of 1 μm, and then dried. Then, a propylene-ethylene random copolymer (MFR; 7, melting point 140 ° C., 2 wt% of a monomer unit based on ethylene) was used. A 60 μm corona-treated (wet index: 40 dynes) unstretched polypropylene film (moisture permeability 5 g / m ² · day) was dry-laminated from the above to obtain a laminated film. Using the laminated film, a packaging bag (150 mm × 150 mm ×) in which 100 ml of saturated saline pure water was heat-sealed and sealed so that a 20 μm corona-treated biaxially stretched polypropylene film using a propylene homopolymer as a raw material was an outer layer. 150 mm). Using this packaging bag, boil (90 ° C-30 minutes)
Was performed. The laminated film was cut out from the raw coated film and the packaging bag after the boil treatment, and the oxygen barrier properties were evaluated. Table 1 shows the results.

Comparative Example 1 The coating liquid B was used as the coating liquid, and the dry film thickness was 1 μm.
Except for the above, a coated film raw material and a laminated film after treatment were obtained and evaluated in the same manner as in Example 1.

Comparative Example 2 The barrier properties were evaluated in the same manner as in Example 1 except that a package was prepared by inverting the outer layer side and the inner layer side of the processed laminated film.

[0072]

[Table 1]

Example 2 Biaxially stretched polyethylene terephthalate as base film
G (moisture permeability 50g / m ^Two・ Day: LUMIRA manufactured by Toray Industries, Inc.
-12 μm) as unstretched polypropylene film
Toray's Tolephane NO (25 μm moisture permeability 14 g /
m^TwoUsing the day), the obtained laminated film
Evaluation of retort sterilization (115 ° C-20 minutes)
The same operation as in Example 1 was performed except that
The processed laminated film was obtained, and the appearance was evaluated. Table of results
It is shown in FIG.

Comparative Example 3 20 L of Soarnol as coating agent (EvOH coating agent)
The same operation as in Example 2 was performed except that
A laminated film after the treatment was obtained, and the appearance was evaluated.

[0075]

[Table 2]

[0076]

The laminated film of the present invention has good oxygen barrier properties and good humidity dependency of oxygen barrier properties by laminating a layer made of a thermoplastic resin having different moisture permeability and a specific polymer gas barrier layer. In addition, the laminated film is excellent in heat sterilization suitability.
Therefore, the laminated film of the present invention is not only suitable as a gas barrier film but also widely useful as a food packaging film.

Claims (1)

[Claims] 1. A layer comprising a thermoplastic resin film, B layer
A laminated film comprising a layer and a layer C composed of a polymer gas barrier layer comprising any one of the following (1) to (3), wherein the layer A and the layer B have different moisture permeability. A laminated film characterized by being a layer. (1) A mixture of a partially hydrolyzed polycondensate of at least one alkoxide selected from the group consisting of metal alkoxides and silicon alkoxides with a water-soluble polymer. (2) A reaction product of the partially hydrolyzed polycondensate and a water-soluble polymer. (3) a mixture with the partially hydrolyzed polycondensate, the water-soluble polymer and the reaction product.