JP2002113826A - Plastic base material and gas-barrier film using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-barrier film which has high gas-barrier properties independent of temperature and humidity even at a high temperature and under a high pressure and is excellent in transparency, printability, and moistureproofing properties. SOLUTION: In the gas-barrier film, a polyolefin in which either the maximum height expressing surface roughness: Ry<1.40 μm or ten point-average roughness: Rz<0.80 μm is a surface roughness which meets the above area is a main component, and a gas-barrier film containing an alkali metal polysilicate expressed by M2O.nSiO2 (M is lithium or a plurality of alkali metals including lithium; n is a mol ratio and 1-20) as a main component is laminated on one surface or both surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging film used in the field of packaging non-foodstuffs such as foodstuffs, pharmaceuticals, and electronic components, and more particularly to a film by suppressing permeation of gases such as oxygen and water vapor. The present invention relates to a gas barrier functional film that suppresses oxidation, decomposition, and alteration of the film.

[0002]

2. Description of the Related Art In recent years, packaging materials used for packaging foods, non-foods, and the like are required to suppress deterioration of contents and maintain their functions and properties. It is necessary to prevent the influence of the gas that alters the substance, and it is required to have a gas barrier function of blocking such gas (gas).

[0003] Conventionally, as a gas barrier layer, a metal foil or a metal-deposited film made of a metal such as aluminum,
Resin films such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, and polyacrylonitrile, or films coated with these resins, and ceramic evaporated films on which inorganic oxides such as silicon oxide and aluminum oxide are further evaporated. Mainly used.

[0004]

However, metal foils and vapor-deposited films are excellent in gas barrier properties, but the contents cannot be confirmed by seeing through the packaging material, the metal detector cannot be used in the inspection, and the disposal after use. In such a case, there is a problem that it must be treated as an incombustible substance. In addition, gas barrier resin films and films coated with them are highly temperature and humidity dependent and cannot maintain a high level of gas barrier properties.Polyvinylidene chloride and polyacrylonitrile can be used as raw materials for harmful substances during disposal and incineration. There are problems such as. Further, the ceramic vapor-deposited film or the like has a problem that the vapor-deposited layer lacks flexibility due to ceramics, so that sufficient attention must be paid to processing suitability, and that the cost is high because the processing machine is expensive.

As a technique for solving such a problem, there is the following proposal as a gas barrier material having a ceramic skeleton provided with flexibility by wet coating which can be manufactured at low cost. 1. A gas barrier material having a coating of a water-soluble dispersion of lithium silicate on the surface of a polymer molded article (Japanese Patent Application Laid-Open No. 49-513)
No. 66). 2. A gas barrier material in which a coating of a dispersion solution of silica and polyvinyl alcohol is provided on a polyester substrate (Japanese Patent Publication No. 63-25615). 3. A gas barrier material for coating an aqueous liquid containing an alkali metal silicate and a silane coupling agent on the surface of a polymer molded product (JP-A-6-238711). 4. A gas barrier material having a composite of a metal alkoxide or a hydrolyzate thereof and a water-soluble resin on a plastic substrate (JP-A-6-192454).

[0006] The above-mentioned gas barrier material is about 1.6 / 1.
It has been confirmed that gas barrier properties and water vapor barrier properties can be imparted by providing an inorganic coating of lithium silicate with a SiO2 / Li2O molar ratio of -4.6 / 1 on a PET substrate. It has long been known that lithium polysilicate is useful as a gas barrier material. However, when a film is formed on a plastic film using lithium polysilicate alone, the molar ratio represented by Li2O.nSiO2 is in the range of n ≦ 5. If not, a film cannot be formed, and n
Lithium polysilicate coatings formed in the range of ≦ 5 also require rapid plastic shrinkage due to rapid thermal contraction due to drying during film formation and lack of flexibility. Damage such as cracks (cracks) occurs and the gas barrier properties are reduced.

The second gas barrier material is M2O.nS
Particle size 50 of iO2 (M is an alkali metal) where n is 50 or more
40 nm or less of silica sol in polyvinyl alcohol
It is formed by applying and drying an aqueous dispersion solution added at a weight ratio of ~ 90 on a polyester substrate, and its insolubility in hot water in the coating has been confirmed.

[0008] The gas barrier material of the above 3 is M2O.nS
A silane coupling agent is blended with an alkali metal silicate (water glass) having n of 2 or more in iO2 (M is an alkali metal) and applied to a polymer molded product having a wetting tension of 50 dyne / cm or more. It was reported that when formed, high adhesion and oxygen barrier properties were obtained. However, although it is described in the present invention that the composition of potassium silicate and the silane coupling agent provides the highest oxygen barrier properties, no mention is made of the surface condition of the substrate.

The above-mentioned gas barrier material is a composite material containing a water-soluble resin (polyvinyl alcohol) in an amount of 5 to 80% by weight with respect to a metal alkoxide of Si or Al or a hydrolyzate thereof, and exhibits a very high gas barrier. it can. However, since the hydrolysis reaction of the metal alkoxide affects the gas barrier function, the hydrolysis reaction must be strictly controlled. Also, in order to develop a gas barrier, dehydration in the coating must be promoted,
High temperature drying exceeding 100 ° C. is required.

The present invention has been made to solve the above-mentioned problems of the prior art, and is excellent in transparency so that the contents can be seen through and a metal detector can be used. Gas barrier properties can be exhibited in a short time and at a low temperature drying step at 100 ° C. or lower. In addition, it has excellent suitability for processing, high gas barrier properties under high temperature and high humidity, and also improves flexibility, which is a drawback of inorganic oxide materials required as packaging materials, and does not use environmentally damaging substances. It is an object to provide an optimal gas barrier film as a material.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the invention of claim 1 is directed to a maximum height representing a surface roughness: Ry <1.40 μm, a 10-point average. Roughness: Any one of Rz <0.80 μm is a plastic base material having a surface roughness that satisfies the above-mentioned conditions, comprising a polyolefin as a main component and a gas barrier coating laminated on one or both surfaces.

According to a second aspect of the present invention, the maximum height representing the surface roughness is Ry <1.40 μm, and the 10-point average roughness is Rz <0.
80 μm is a surface roughness satisfying the above conditions,
A plastic substrate comprising a polyolefin as a main component and a gas-barrier coating laminated on one or both surfaces.

According to a third aspect of the present invention, the gas barrier coating is an alkali metal represented by M2O.nSiO2 (M is lithium or a plurality of alkali metals containing lithium, and n is a molar ratio in the range of 1 to 20). The gas barrier film using a plastic substrate according to claim 1, wherein the gas barrier film is mainly composed of polysilicate.

The invention according to claim 4 is the gas barrier film according to claim 3, wherein an anchor coat layer is provided between the plastic substrate and the gas barrier coating.

The invention according to claim 5 is the gas barrier film according to claim 4, wherein the anchor coat layer is an organic polymer having a urethane bond and / or a urea bond.

The invention according to claim 6 is the gas barrier film according to claim 3, characterized in that a nitrogen compound and / or a water-soluble polymer is further blended into the alkali metal polysilicate.

The invention according to claim 7 is the gas barrier film according to claim 6, wherein the nitrogen compound is an amine containing an amino group-containing silane coupling agent.

The invention according to claim 8 is that the water-soluble polymer is
The gas barrier film according to claim 6, wherein the gas barrier film is at least one selected from saccharides, polyvinyl alcohol, and derivatives thereof.

[0019]

According to the present invention, the maximum height Ry <1.40μ
m, any one of 10 point average roughness Rz <0.80 μm has a surface roughness that satisfies the above conditions, and a gas barrier coating is laminated on a plastic base material containing polyolefin as a main component. M2O.nSi
The main component is an alkali metal polysilicate represented by O2 (M is lithium or a plurality of alkali metals containing lithium, and n is within a range of 1 to 20 in molar ratio).

These numerical values representing the surface roughness can be said to be smoother as the numerical value is smaller. Particularly, in the case of a plastic base material mainly composed of a polyolefin-based material lacking in heat resistance and having a high heat shrinkage, If there are many projections and irregularities, pinholes and distortions due to distortion and film thickness of the gas barrier coating formed of ultra-thin film will occur,
The higher the smoothness, the more effective it is in the development of gas barrier properties.

Further, by providing an anchor coat layer between a plastic base material containing polyolefin as a main component and a gas barrier coating, it is possible to improve the wettability and adhesion to a polyolefin having a low polarity. Effective for uniform formation of functional coating.

Furthermore, by introducing a nitrogen compound and / or a water-soluble polymer into the alkali metal polysilicate, the wettability of the aqueous solution of the gas barrier coating and the adhesion of the gas barrier coating can be improved. By introducing the organic component (1), cracking and foaming of the gas barrier coating film due to appropriate flexibility and suppression of rapid shrinkage after coating and drying can be prevented.

In particular, by introducing a nitrogen compound, that is, forming a silicon oxide film containing lithium, nitrogen, and carbon as essential components, the plastic substrate containing a polyolefin as a main component can be dried at an extremely low temperature that does not cause thermal damage. Since it has a very dense bond, it has an oxygen barrier property with very little dependence on temperature and humidity, a high water vapor barrier property under a high temperature and high humidity environment, and a highly balanced advanced gas barrier property.

Since the above gas barrier material can be applied by wet coating, an existing gravure printing machine or the like can be used. In addition, by using a polyolefin film, such as a cyclic olefin copolymer (COC), having a high Tg (glass transition point), a high moisture proof, a high transparency layer, and a heat sealing layer, a multi-layered polyolefin film as a base material, Many functions can be provided.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the maximum height representing the surface roughness: Ry <1.40 μm, 10-point average roughness: Rz <0.
Either 80 μm is a surface roughness satisfying the above-mentioned region, and a plastic substrate containing polyolefin as a main component and a gas barrier coating, particularly M2O.nSiO2 (M is lithium or lithium) on one or both surfaces of the plastic substrate. A plurality of alkali metals, wherein n is a molar ratio in the range of 1 to 20), which is a gas barrier film characterized by laminating a gas barrier coating mainly composed of an alkali metal polysilicate.

The above-mentioned plastic materials include, for example, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polystyrene films, MXD6-nylon,
It refers to a polyamide film such as nylon, an engineering plastic film such as a polycarbonate film or a polyimide film, etc., but the maximum height of the present invention: Ry <1.40 μm, 10
Point average roughness: A plastic substrate satisfying the surface roughness condition of Rz <0.80 μm has a low Tg (glass transition point),
A polyolefin film lacking in heat resistance and having a large heat shrinkage corresponds to this. Polyolefin films represented by polypropylene and polyethylene are characterized by low resin price, good transparency, chemical resistance, high moisture resistance,
Good stretchability, and can respond to a wide range of additives. Since the gas barrier composite coating of the present invention can be dried at a low temperature, it can be applied regardless of stretching or unstretching, but stable coating properties, film strength, dimensional stability, printability, price, disposal In consideration of the properties, transparency, hygiene and the like, a biaxially stretched single-layer film or a co-extruded composite multilayer film is more preferable.

Further, the polyolefin film includes a biaxially stretched film in which two or more layers are simultaneously formed by coextrusion, and is a cyclic film obtained by copolymerizing ethylene with dicyclopentadiene, norbornene, cyclohexene, or the like. High moisture-proof layer mainly composed of olefin copolymer, high moisture-proof polypropylene laminated on one or both sides with a polypropylene layer, etc. for printability, price, oil resistance, adhesion, etc., and polyolefin-based low-temperature heat-sealing layer on one side By using a heat-sealable polypropylene film or the like having a base material as a base material, it is possible to simplify applications in which a high degree of moisture resistance is required and to simplify the step of laminating a sealant film.

The components of the substrate include various known additives such as suitability as a packaging material such as suitability for printing, suitability for post-processing, suitability for filling and packaging, suitability for contents, and suitability for film formation. Stabilizers, such as antistatic agents, plasticizers, lubricants, antioxidants, etc. may be added, but lubricants such as silica beads, talc, calcium-based fillers and antistatic agents that excessively bleed on the surface, etc. Since many of them have an effect on the surface smoothness, it is more preferable to reduce the amount of these additives as much as possible.

Although the thickness of the substrate is not particularly limited, it is practically in the range of 3 to 200 μm in consideration of suitability as a packaging material and the case of laminating another resin layer. It is more preferable that it is in the range of 3 to 30 μm depending on the application.

The surface of the plastic substrate containing the above-mentioned polyolefin as a main component is improved in the polarity of the outermost surface of the substrate by corona discharge treatment, low-temperature plasma treatment, flame treatment or the like on one or both surfaces of the substrate surface in consideration of adhesion. Those that have been made are preferred. By these treatments, the wettability and adhesion of the anchor coating liquid provided by the wet coating wet process are improved.

The anchor coat layer of the present invention is provided between the plastic base material containing the polyolefin as a main component and the gas barrier coating, and has the object of improving the film forming property and adhesion of the gas barrier coating layer. Provided. In addition to polyolefin-based films that do not provide sufficient surface wetting tension in the above-mentioned surface modification treatment, alkalis from gas-barrier coatings formed during gas-barrier coating formation and storage in high-humidity environments, which are characteristically seen in polyester films Substrate damage due to elution of components (breaking of polymer chains)
The effect of preventing is also obtained.

The above-mentioned anchor coat layer is provided by coating, but it is more preferable to dissolve the material in water or an organic solvent and apply it by wet coating in consideration of the surface smoothness. Examples of the material include polyethyleneimine or a derivative thereof, a silane coupling agent, an organic titanate, polyacryl, polyvinyl acetal, polyester, polyurethane, polycarbonate, polyurea, polyamide, polyolefin-based emulsion, polyimide, melamine, and phenol.

In consideration of alkali resistance of the anchor coat layer, a resin having no ester bond in the main chain is preferable, and in consideration of adhesion at low temperature drying, an organic polymer having at least one urethane bond and at least one urea bond. Is more preferably included. The urethane bond and the urea bond may be a polymer introduced in advance in the polymerization step, but may be an isocyanate compound having an isocyanate group with a polyol such as an acrylic polyol, a methacrylic polyol, or a polyvinyl acetal, or an amine resin having an amino group and an epoxy resin. A urethane bond may be formed by reacting an epoxy compound having a group and a glycidyl group, or a urea bond may be formed by reacting an isocyanate compound with water or an amine resin having an amino group.

The above-mentioned isocyanate compounds generally include TDI (tolylene diisocyanate), MDI (diphenylmethane diisocyanate) and NDI (1,5-naphthalenediisocyanate) having an aromatic skeleton, and an aliphatic skeleton having an aliphatic skeleton. Examples include HDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), XDI (xylylene diisocyanate), and H ₆ XDI (hydrogenated XDI).
Any of these may be used. However, considering the barrier properties and coating properties, the glass transition temperature (Tg)
It is more preferable to use any one of a TDI system, an MDI system, and an XDI system, which have a high NDI. Further, uretdione or isocyanurate obtained by an isocyanate polymerization reaction may be used, or an adduct obtained by performing an addition reaction with trimethylolpropane or the like for easy handling may be used.

The glass transition point (Tg) of the resin constituting the anchor coat layer is preferably 30 ° C. or higher. 30 ° C
When the content is below, the anchor coat layer may be softened when the gas barrier coating layer is dried, and the gas barrier coating layer may be cracked and may not exhibit the barrier property. Considering the drying temperature of the gas barrier coating layer, the glass transition point is 60 ° C.
The above is more preferable.

As an additive, an inorganic component may be introduced with a silane coupling agent, colloidal silica, organic titanate, alumina sol, clay mineral, calcium carbonate, titanium oxide, etc. in consideration of the adhesion to the gas barrier coating layer. Further, a surfactant such as a quaternary ammonium salt or an amine resin such as a tertiary amine may be introduced to improve the wettability. These may be introduced as a main skeleton in the polymer polymerization stage, may be reacted at the side chain terminal, or may be directly added directly to a diluted solution in use.

The thickness of the anchor coat layer is not particularly limited. However, if the thickness is less than 0.001 μm, adhesion or film forming property cannot be obtained, and if it is more than 5 μm, it is uneconomical. Generally, the range of 0.005 to 1 μm is practical and more preferable. As a forming method, an ordinary wet coating method such as a dipping method, a roll coating, a gravure coating, a reverse coating, an air knife coating, a comma coating, a die coating, a screen printing method, a spray coating, and a gravure offset method can be used. The coating is applied to one or both surfaces of the substrate by using these coating methods. The drying method for drying is a known and commonly used drying method such as hot air drying, hot roll drying, and infrared irradiation, and is not particularly limited.

Next, the gas barrier coating layer of the present invention will be described. The purpose of the layer is to provide a high oxygen barrier property without physical property degradation under high temperature and high humidity with very little dependence on temperature and humidity. In order to achieve the above object, the gas barrier coating may be formed of M2O.nSiO2 (M is lithium or a plurality of alkali metals containing lithium, n
Must be a coating mainly composed of an alkali metal polysilicate represented by the following formula:

Lithium silicate, which is an essential component of the above-mentioned alkali metal polysilicate having gas barrier properties, is represented by Li2O.nSiO2 (n is a molar ratio), and its solution is generally water glass (water of sodium silicate aqueous solution) using water as a solvent. This is an aqueous solution of an alkali silicate known as a common name. An alkali metal other than lithium refers to all elements belonging to Group 1A, but industrially relatively inexpensive sodium and potassium are generally used in many cases. However, a dry coating of an aqueous alkali silicate solution containing one or more alkali metals containing no lithium cannot provide high oxygen barrier properties with little dependence on temperature and humidity and high water vapor barrier properties under high temperature and high humidity.

First, by blending a water-soluble polymer having compatibility with an aqueous solution of lithium silicate and having a flexible organic component as a skeleton, a wide range of lithium poly-oxide having a molar ratio of 1 to 20 represented by Li2O.nSiO2 is obtained. A silicate film can be formed, and even when applied as a gas barrier material onto a plastic substrate, shrinkage is suppressed and a flexible film without cracks can be formed.

The above-mentioned water-soluble polymer is a polymer having a hydroxyl group, a carboxyl group or an amino group, and needs to be water-soluble in view of compatibility with an aqueous alkali silicate solution. For example, polyvinyl alcohol or derivatives thereof, ethylene vinyl alcohol copolymer, saccharides such as starches and celluloses, polyacrylic acid, polymethacrylic acid, and copolymers thereof can be used. Further, in consideration of compatibility with an aqueous alkali silicate solution and gas barrier properties, a region from weakly acidic to weakly alkaline is more preferable, and a saccharide, polyvinyl alcohol or a derivative thereof is more preferable.

The above saccharides refer to organic compounds containing glucose as a main component, and include oligosaccharides, oligosaccharides, and polysaccharides. The saccharides used in the present invention are more preferably starches and celluloses belonging to polysaccharides in which glucose is polymerized in consideration of the film-forming properties and flexibility of the gas barrier coating.

The above-mentioned polyvinyl alcohol is a polymer obtained by polymerizing and saponifying vinyl acetate as a main raw material. Polyvinyl alcohol used in the present invention includes film-forming properties, flexibility and phase of a gas barrier coating. Solubility
Considering water resistance, polymerization degree 300-3000, saponification degree 95
More than mol% is more preferable. In addition, the polyvinyl alcohol derivative has an alkoxysilyl group, a carboxyl group, an amino group,
Modified polyvinyl alcohol into which sulfonic acid groups, acetoacetyl groups, and the like are introduced at 10 mol% or less is included, and these may be selected according to compatibility with an aqueous alkali silicate solution, adhesion to a plastic substrate, or the like.
More than one kind can be mixed.

A known method can be used for mixing the alkali metal polysilicate and the water-soluble polymer without any particular limitation. The mixing ratio of SiO ₂ in the alkali metal polysilicate is determined based on gas barrier properties, flexibility, and water resistance.
The weight ratio of (silica component) / water-soluble polymer is 50/50.
It is preferably in the range of 99.99 / 0.01.
If the amount of the water-soluble polymer is more than 50% by weight, the gas barrier property is reduced due to moisture absorption of the water-soluble polymer, and 0.01% by weight.
If it is less than 3, the effect of suppressing shrinkage during the formation of the alkali metal polysilicate film cannot be obtained.

As a method for imparting a water vapor barrier property by drying at a low temperature, sodium, potassium, calcium,
By introducing magnesium, sulfur, phosphorus, nitrogen and the like, the densification of the silicon oxide film is promoted and the water vapor barrier property is improved. Because the base material is a plastic material, adhesion, flexibility, oxygen barrier properties, and water vapor barrier properties due to short-time low-temperature drying due to problems such as adhesion, flexibility, stability when flying, and prevention of elution when moisture is absorbed. Most preferably, nitrogen is introduced by a nitrogen compound such as an amine containing an amino group-containing silane coupling agent as an organic component.

A film obtained by mixing a nitrogen compound with lithium polysilicate will be described. As a method for introducing nitrogen into lithium polysilicate, a gas introduction method in which dry nitrogen gas or ammonia gas is substituted and vapor or water is penetrated by heating or pressurizing, or a solid or liquid material is directly dissolved in an aqueous alkali silicate solution at room temperature However, the latter is characterized in that it can be dissolved and diffused with a simple stirring device, and that the amount of nitrogen introduced can be easily controlled.

Examples of the nitrogen compound include ammonia, halogenoamine, dihalogenoamine, nitrogen halide, metal amide, metal imide, metal nitride, amines, ammonium salt, alkyl ammonium salt, dialkyl ammonium salt, and trialkyl ammonium salt. , Tetraalkylammonium salt, hydrogen azide, metal azide, hydrazine, hydrazium salt, hydroxylamine, hydroxylammonium salt, nitrate, hyponitrite, nitroxylate, nitrite, peroxonitrite, peroxonitrite, nitrosyl halide, Halogenated nitriles, halogen nitrates, cyanides, cyanates, thiocyanates,
Phosphorus nitride, nitrogen sulfide or derivatives thereof are included, but considering stability, safety, environmental friendliness, price, compatibility with alkali silicate aqueous solution, film strength, flexibility, shrinkage prevention, etc., alkaline aqueous solution Amines that can be easily dissolved and can introduce a highly flexible hydrocarbon residue are more preferable.

The above-mentioned amines are compounds in which a hydrogen atom of ammonia is substituted with a hydrocarbon residue, and an amino group (N
There are a primary amine having H ₂ —), a secondary amine having an imino group (—NH—), a tertiary amine and a quaternary ammonium salt in which all hydrogens are substituted, and a polyamine having many of these functional groups. Also included are ethyleneimine-based polymers such as polyethyleneimine, aminoethylated resins, and aziridinyl group-containing compounds. As an amino group-containing silane coupling agent which is a monoamine or a diamine having an alkoxysilyl group, N- (2-aminoethyl) 3
-Aminopropylmethyldimethoxysilane, N- (2
-Aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-phenyl-3- There are aminopropyltrimethoxysilane and the like, and either of these may be directly added, or they may be introduced after being hydrolyzed and silanolized in an aqueous solution before compounding.

The lithium polysilicate compounded with the nitrogen compound as described above is further coated with the above-mentioned compound for the purpose of improving the film formation stability during coating and drying, the stability after forming the film, the oxygen barrier property and the flexibility. Such a water-soluble polymer may be introduced. By introducing these in appropriate amounts depending on the nitrogen compound to be used, the above-described high functions can be imparted without hindering the characteristics of the lithium polysilicate and the nitrogen compound.

Coatings formed from alkali silicates (water glass), including lithium polysilicate, have an efflorescence phenomenon in which the coatings are whitened by reacting with carbon dioxide gas or moisture in the air over time. As means for solving these, metal powder and polyvalent metal oxide, polyvalent metal hydroxide, phosphate, and the like in alkali polysilicate
Methods for adding and dispersing inorganic compound particles such as borates are known.
It may be added as needed to the extent that the transparency is not reduced. Also,
A similar effect can be obtained by adding a nitrogen compound such as an amine containing an amino group-containing silane coupling agent, or a water-soluble polymer such as a saccharide or polyvinyl alcohol.

It is also possible to combine inexpensive sodium polysilicate and potassium polysilicate, which is known to have water resistance, with lithium polysilicate, thereby reducing the price without impairing the gas barrier function of lithium polysilicate. An alkali metal polysilicate having characteristics such as water resistance can be obtained. When an alkali metal other than lithium is added, the molar ratio of Li ₂ O / M ′ ₂ O (M ′ is an alkali metal other than lithium) is preferably 1 or more in consideration of gas barrier properties.

As described above, a nitrogen compound such as an amine is added to an alkali metal polysilicate in a wide range of a molar ratio n represented by M 2 O · nSiO 2 (M is lithium or a plurality of alkali metals containing lithium) of 1 to 20; By adding a water-soluble polymer such as saccharides or polyvinyl alcohol as needed, film shrinkage, flexibility and crack resistance due to low shrinkage can be imparted, and a more advanced gas barrier in addition to oxygen barrier properties as well as water vapor barrier properties. Can have functions.

A known method can be used for mixing the alkali metal polysilicate with the nitrogen compound or the water-soluble polymer, and is not particularly limited. Further, from the viewpoint of gas barrier properties, coating strength and water resistance, it is preferable that the weight ratio of SiO2 (silica component) in the alkali metal polysilicate is 50% or more of the entire solid content. This is because if the content of SiO2 (silica component) is less than 50%, the gas barrier property is reduced due to moisture absorption of the nitrogen compound and the water-soluble polymer.

The thickness of the gas barrier coating layer is generally preferably such that the thickness after drying is in the range of 0.01 to 100 μm, more preferably in the range of 0.01 to 10 μm. That is. 0.01
If it is less than 10 μm, it is difficult to obtain a uniform coating film.
When the thickness exceeds μm, the coating is liable to be broken and is uneconomical.

As a method for forming the gas barrier coating layer, a usual wet coating method can be used. For example, dipping method, roll coat, gravure coat, reverse coat, air knife coat, comma coat, die coat, screen printing method, spray coat,
A gravure offset method or the like can be used. The coating is applied to one or both surfaces of the substrate by using these coating methods. The drying method for drying is a known and commonly used drying method such as hot air drying, hot roll drying, and infrared irradiation, and is not particularly limited.

Further, a practical laminated structure as a packaging material can be provided on the side opposite to the gas barrier coating layer of the plastic substrate or the gas barrier coating layer. For example, it is a printing layer or a heat sealing layer such as a thermoplastic resin. Further, an adhesion layer (overcoat layer) can be provided between the gas barrier coating layer and the printing layer.

The printed layer is used for the purpose of merchantability, cosmetics, display effect, etc. of the contents to be packaged, and is made of urethane, acrylic, nitrocellulose, polyamide,
A layer composed of printing ink in which additives such as pigments and vehicles, plasticizers, desiccants, stabilizers, etc. are added to an ink binder resin such as polyvinyl chloride and natural vegetable oils, and characters, pictures, etc. Are formed. As a forming method, for example, a well-known printing method such as an offset printing method, a gravure printing method, a flexographic printing method, a silk screen printing method, or a well-known coating method such as a roll coat, a knife edge coat, or a gravure coat can be used. . The thickness is
It is appropriately selected in the range of 0.01 to 2.0 μm.

When a multi-color gravure printing machine or the like is used for laminating the printing layers, the gas barrier coating layer may be provided first, and then the printing layers may be provided in-line using the same printing machine.

The heat seal layer is used for an adhesive portion when forming a bag-like package, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, Ethylene-
Resins such as methacrylic acid ester copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, and cross-linked metals thereof are used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm.

The heat sealing layer may be formed by a dry laminating method in which a film-like material made of the above-described resin is bonded using a two-component curable urethane adhesive, or a non-solvent type in which the film is bonded using a solventless adhesive. Any of a dry lamination method, an extrusion lamination method in which the above-described resin is heated and melted, and extruded in a curtain shape, and the like can be formed by a known lamination method.

The film substrate of the present invention and a gas barrier film using the same will be further described with reference to specific examples.

<Experiment 1><Preparation of Gas Barrier Coating Solution> 1) Lithium silicate aqueous solution (Li2O.nSiO
A silane coupling agent ("Sila Ace S320" manufactured by Chisso Corp., N- (2-aminoethyl)
An aqueous solution in which 3-aminopropyltrimethoxysilane) was dissolved and an aqueous solution in which a silane-modified polyvinyl alcohol (“R-2105” manufactured by Kuraray Co., Ltd., saponification degree: about 98.5 mol%) was dissolved as a water-soluble polymer were SiO 2 / Silane coupling agent hydrolyzate / water-soluble polymer in a weight conversion of 85/10/5, followed by stirring to obtain gas barrier coating liquid 1-1.

<Preparation of Anchor Coating Solution> 2) Polymethyl methacrylate (PMMA) -based polyol resin (trade name “6080NT” manufactured by Toei Kasei Co., Ltd. (glass transition point: 100 ° C.)) was dissolved in ethyl acetate, and then dissolved in isocyanate. A compound (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) was adjusted so that the solid content was 70/30 parts by weight and the total solid content was 5%.
-2 was obtained.

<Example 1-1> As the base material A, a thickness of 20
Anchor coating liquid 1-2 is applied to the corona discharge treated surface of a biaxially stretched polypropylene film having a thickness of μm (trade name “P2102” manufactured by Toyobo Co., Ltd.) with a Mayer bar # 3, dried at 50 ° C. for 1 minute, and further dried. Gas barrier coating 1
1 was applied with a Mayer bar # 3 and dried at 70 ° C. for 1 minute to obtain a gas barrier film of the present invention.

<Example 1-2> In Example 1-1,
As the base material B, a biaxially oriented polypropylene film having a thickness of 30 μm (trade name “P2108” manufactured by Toyobo Co., Ltd.)
A gas barrier film of the present invention was obtained in the same manner except that a single-sided corona discharge treatment was used.

<Comparative Example 1-1> In Example 1-1,
As the substrate C, a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “PB210” manufactured by Nimura Chemical Industry Co., Ltd.)
J ", single-sided corona discharge treatment), except that silica coated film was obtained.

<Comparative Example 1-2> In Example 1-1,
A silica-coated film was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “M-1” manufactured by Tosello Co., Ltd., single-sided corona discharge treatment) was used as the substrate D.

<Example 1-3> In Example 1-1,
A gas barrier film of the present invention was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “PF20” manufactured by Tokuyama Corporation, single-sided corona discharge treatment) was used as the base material E.

<Comparative Example 1-3> In Example 1-1,
A silica-coated film was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “HE-1” manufactured by Tosello Co., Ltd., single-sided corona discharge treatment) was used as the base material F.

<Example 1-4> In Example 1-1,
A gas barrier film of the present invention was obtained in the same manner except that a 22 μm-thick biaxially stretched polypropylene film (trade name “YB22” manufactured by Toray Industries, Inc., double-sided corona discharge treatment) was used as the base material G.

<Evaluation> Table 1 shows each of the plastic substrates of Examples and Comparative Examples and a laminate using the same.
Oxygen permeability (cm ³ / m ² · 24 hr), (2) surface roughness (Ra,
Ry, Rz, Sm), (3) the appearance of the coating, and (4) the evaluation results of the lamination strength.

(1) Oxygen permeability Oxygen permeability measuring device (OXTRAN- manufactured by MOCON)
2/20), each laminate was measured in an atmosphere at 30 ° C. and 90% RH.

(2) Surface Roughness (Ra, Ry, Rz, Sm) Surface Roughness Measurement Machine (surfcom5 manufactured by Tokyo Seimitsu Co., Ltd.)
54AD) and the Ra on the surface of the base film is measured by a stylus method.
(Arithmetic mean roughness: μm), Ry (maximum height: μm), Rz
(10-point average roughness: μm), Sm (average interval between irregularities: μ)
m) was measured.・ JIS B0601 Surface roughness-According to the definition and indication.・ Vertical magnification: 20000 × ・ Pickup needle: 2 μmR, 90 ° cone ・ Measurement length: 2.5 mm ・ Cut off: 0.80 mm ・ Measuring speed: 0.12 mm / min

(3) Appearance of Coating Film After coating and drying, the surface of the gas barrier coating film was visually observed to confirm the presence or absence of minute cracks.

(4) Laminate strength DRY laminating adhesive diluted with ethyl acetate on the coated side (Takenate A5 manufactured by Takeda Pharmaceutical Co., Ltd.)
15 / A50 ") was applied at about 10 g / m ^{2 in} WET and dried, and then a sealant film (30 μm, manufactured by Idemitsu Petrochemical Co., Ltd.)
Thickness unstretched polypropylene film "RS50
3C ”) and aged at 40 ° C. for 2 days to form a soft packaging material. This was measured using a peel tester (Tensilon: RTC125 manufactured by Orientec Co., Ltd.).
Using 0), the measurement was performed under the conditions of a sample width: 15 mm, a peel angle: T-shaped peel, and a peel speed: 300 mm / min.

[0076]

[Table 1]

The substrates A to E are single-layer polypropylene films, and the substrates FG are three-layer coextruded polypropylene films having a high moisture-proof layer as an intermediate layer. Compared to the example, in the comparative example, Ra <0.05, Ry <1.40, R
Since any one of z <0.80 does not satisfy the surface roughness, the oxygen permeability is insufficient as a gas barrier substrate. In the examples, an effective oxygen barrier property for packaging applications was obtained, and a uniform coating without cracks in the coating and a laminate strength sufficient for practical use were obtained.

<Experiment 2><Preparation of Gas Barrier Coating Solution> 1) Lithium silicate aqueous solution (Li2O.nSiO
A silane coupling agent ("Sila Ace S320" manufactured by Chisso Corp., N- (2-aminoethyl)
An aqueous solution in which 3-aminopropyltrimethoxysilane) was dissolved and an aqueous solution in which a silane-modified polyvinyl alcohol (“R-2105” manufactured by Kuraray Co., Ltd., saponification degree: about 98.5 mol%) was dissolved as a water-soluble polymer were SiO 2 / Silane coupling agent hydrolyzate / water-soluble polymer in a weight conversion of 85/10/5, followed by stirring to obtain gas barrier coating solution 2-1.

<Preparation of Anchor Coating Solution> 3) Polyvinyl acetal (PVAc) resin (trade name “KS-1” (glass transition point: 106 ° C.), manufactured by Sekisui Chemical Co., Ltd.) is dissolved in ethyl acetate, and then an isocyanate compound ( Takeda Pharmaceutical Co., Ltd. product name “D204EA”) was adjusted so that the solid content weight ratio was 70/30 parts and the total solid content was 5% to obtain an anchor coat liquid 2-2.

<Example 2-1> As the base material A, a thickness of 20
Anchor coating solution 2-2 was applied to the corona discharge treated surface of a biaxially oriented polypropylene film of μm (trade name “P2102” manufactured by Toyobo Co., Ltd.) with a Mayer bar # 3, dried at 50 ° C. for 1 minute, and further dried. Gas barrier coating 2-
1 was applied with a Mayer bar # 3 and dried at 70 ° C. for 1 minute to obtain a gas barrier film of the present invention.

<Example 2-2> In Example 2-1.
As the base material B, a biaxially oriented polypropylene film having a thickness of 30 μm (trade name “P2108” manufactured by Toyobo Co., Ltd.)
A gas barrier film of the present invention was obtained in the same manner except that a single-sided corona discharge treatment was used.

<Comparative Example 2-1> In Example 2-1,
As the substrate C, a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “PB210” manufactured by Nimura Chemical Industry Co., Ltd.)
J ", single-sided corona discharge treatment), except that silica coated film was obtained.

<Comparative Example 2-2> In Example 2-1,
A silica-coated film was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “M-1” manufactured by Tosello Co., Ltd., single-sided corona discharge treatment) was used as the substrate D.

<Embodiment 2-3> In Embodiment 2-1,
A gas barrier film of the present invention was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “PF20” manufactured by Tokuyama Corporation, single-sided corona discharge treatment) was used as the base material E.

<Comparative Example 2-3> In Example 2-1,
A silica-coated film was obtained in the same manner except that a biaxially stretched polypropylene film having a thickness of 20 μm (trade name “HE-1” manufactured by Tosello Co., Ltd., single-sided corona discharge treatment) was used as the base material F.

<Example 2-4> In Example 2-1,
A gas barrier film of the present invention was obtained in the same manner except that a 22 μm-thick biaxially stretched polypropylene film (trade name “YB22” manufactured by Toray Industries, Inc., double-sided corona discharge treatment) was used as the base material G.

<Evaluation> Table 1 shows (1) oxygen permeability (cm ³ / m ² · 24 hr) and (2) surface roughness of each of the film substrates of Examples and Comparative Examples and the laminates using the same. (Ra, R
y, Rz, Sm), (3) the appearance of the coating, and (4) the evaluation results of the lamination strength.

(1) Oxygen permeability Oxygen permeability measuring device (OXTRAN- manufactured by MOCON)
2/20), each laminate was measured in an atmosphere at 30 ° C. and 90% RH.

(2) Surface Roughness (Ra, Ry, Rz, Sm) Surface Roughness Measurement Machine (surfcom5 manufactured by Tokyo Seimitsu Co., Ltd.)
54AD), and the surface of the film substrate is
a (arithmetic mean roughness: μm), Ry (maximum height: μm), R
z (10-point average roughness: μm), Sm (average interval of unevenness:
μm).・ JIS B0601 Surface roughness-According to the definition and indication.・ Vertical magnification: 20000 times ・ Pickup needle: 2 μmR, 90 ° cone ・ Measurement length: 2.5 mm ・ Cut off: 0.80 mm ・ Measuring speed: 0.12 mm / min

(3) Coating Appearance The gas barrier coating surface after coating and drying was visually observed to confirm the presence or absence of minute cracks.

(4) Laminate strength DRY laminating adhesive diluted with ethyl acetate on the coating surface side (Takenate A5 manufactured by Takeda Pharmaceutical Co., Ltd.)
15 / A50 ") was applied at about 10 g / m ^{2 in} WET and dried, and then a sealant film (30 μm, manufactured by Idemitsu Petrochemical Co., Ltd.)
Thickness unstretched polypropylene film "RS50
3C ”) and aged at 40 ° C. for 2 days to form a soft packaging material. This was measured using a peel tester (Tensilon: RTC125 manufactured by Orientec Co., Ltd.).
Using 0), the measurement was performed under the conditions of a sample width: 15 mm, a peel angle: T-shaped peel, and a peel speed: 300 mm / min.

[0092]

[Table 2]

The substrates A to E are single-layer polypropylene films, and the substrates FG are three-layer coextruded polypropylene films having a high moisture-proof layer as an intermediate layer. In contrast to the examples, in the comparative example, any one of Ry <1.40 and Rz <0.80 does not satisfy the surface roughness, and thus has an insufficient oxygen permeability as a gas barrier substrate. . In the examples, an effective oxygen barrier property for packaging applications was obtained, and a uniform coating without cracks in the coating and a laminate strength sufficient for practical use were obtained. Furthermore, the results of Experiment 1 and Experiment 2 are summarized in FIGS. 1, 2 and 3, and even if the oxygen permeability data of two different resin-based anchor coating agents are superimposed, Ra, Ry, Rz Oxygen permeability is also increased as the surface roughness numerical value of the base material represented by is increased, by controlling the surface roughness state of the base material,
It can be said that the oxygen permeability of the gas barrier coating can be arbitrarily controlled.

[0094]

According to the present invention, a high degree of oxygen barrier expression can be obtained in a very low temperature drying process of 100 ° C. or less, which cannot be obtained by a ceramic skeleton gas barrier material using a sol-gel method which has been proposed many times before. To provide a gas barrier coating that can be applied to a polyolefin-based substrate that has poor surface polarity and lacks heat resistance by providing an anchor coat layer, and a stable oxygen barrier even if exposed to high temperature and high humidity for a long period of time. Therefore, it is extremely effective as a packaging material for perishable contents such as foods having a high water content and a high water activity. Therefore, according to the present invention, a high oxygen barrier property independent of temperature and humidity even under high temperature and high humidity corresponding to the summer environment in Japan, and a high degree of transparency, printability and moisture proofness by using a polyolefin film as a base material. It has excellent adhesion, processability, and flexibility, and can be widely used in the field of packaging.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between Ra (arithmetic roughness) and oxygen permeability for the results of Experiments 1 and 2.

FIG. 2 is a diagram showing the relationship between Ry (maximum height) and oxygen permeability for the results of Experiments 1 and 2.

FIG. 3 is a diagram showing the relationship between Rz (10-point average roughness) and oxygen permeability for the results of Experiments 1 and 2.

FIG. 4 is a cross-sectional view of the gas barrier film of the present invention.

FIG. 5 is a sectional view showing another example of the gas barrier film of the present invention.

[Explanation of symbols]

 1 plastic substrate 2 gas barrier coating layer 3 anchor coating layer

Continued on front page F-term (reference) 4F006 AA12 AA15 AA35 AA36 AA38 AA39 AB03 AB20 AB39 AB43 AB67 BA05 CA07 4F100 AA17B AA17C AA20B AA20C AK01B AK01C AK03A AK07A AK51G BA02 BA03 J07 BA10BBABJB BAB BAB BAB BAB BAB YY00A

Claims (8)

[Claims] 1. A maximum height representing surface roughness: Ry <1.40
μm, 10-point average roughness: any one of Rz <0.80 μm is a surface roughness that satisfies the above-mentioned conditions, and is a plastic substrate characterized by comprising a polyolefin as a main component and a gas-barrier coating laminated on one or both surfaces. Wood. 2. A maximum height representing surface roughness: Ry <1.40.
μm, 10-point average roughness: Rz <0.80 μm, all of which have a surface roughness that satisfies the above conditions. A plastic base material comprising a polyolefin as a main component and a gas barrier coating laminated on one or both surfaces. . 3. The gas barrier coating according to claim 2, wherein the gas barrier coating is M2O.nSi.
2. An alkali metal polysilicate represented by O2 (M is lithium or a plurality of alkali metals containing lithium, and n is a molar ratio in the range of 1 to 20), wherein the main component is an alkali metal polysilicate. Item 3. A gas barrier film using the plastic substrate according to any one of items 2. 4. The gas barrier film according to claim 3, wherein an anchor coat layer is provided between the plastic substrate and the gas barrier coating. 5. The gas barrier film according to claim 4, wherein the anchor coat layer is an organic polymer having a urethane bond and / or a urea bond. 6. The gas barrier film according to claim 3, wherein the alkali metal polysilicate further contains a nitrogen compound and / or a water-soluble polymer. 7. The gas barrier film according to claim 6, wherein the nitrogen compound is an amine containing an amino group-containing silane coupling agent. 8. The gas barrier film according to claim 6, wherein the water-soluble polymer is at least one selected from saccharides, polyvinyl alcohol and derivatives thereof.