JP3119107B2 - Transparent laminate having gas barrier properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent laminate used in the field of packaging foods, pharmaceuticals, precision electronic parts and the like, and more particularly to a transparent laminate having gas barrier properties.

[0002]

2. Description of the Related Art In recent years, packaging materials used for packaging foods, pharmaceuticals, precision electronic parts, etc., suppress deterioration of contents, especially oxidation and deterioration of proteins and oils and fats in foods, and further improve taste and freshness. In medicines that need to be maintained and handled under aseptic conditions, suppress the deterioration of active ingredients and maintain their efficacy.In precision electronic components, prevent corrosion of metal parts and insulation failure in precision electronic components. For this reason, it is necessary to prevent the effects of oxygen, water vapor, and other gases that alter the contents of the packaging material, and it is required to have a gas barrier property that blocks these gases.

[0003] For this reason, polymer resins generally known to have relatively high gas barrier properties, such as polypropylene (KOP), polyethylene terephthalate (KPET) or ethylene vinyl alcohol copolymer (EVOH) coated with a vinylidene chloride resin, have conventionally been used. A packaging film using the composition as a gas barrier material in a packaging material, a metal foil made of a metal such as Al, and a suitable polymer resin composition (even a resin that does not have high gas barrier properties by itself)
A packaging film using a metal vapor-deposited film obtained by vapor-depositing a metal or a metal compound such as Al on a packaging material has been generally used.

[0004] However, the packaging film using only the above-mentioned polymer resin composition is not only inferior in gas barrier property but also inferior to a metal-deposited film in which a foil or a vapor-deposited film is formed using a metal or a metal compound such as Al. In addition, the gas barrier property is easily affected by temperature and humidity, and depending on the change, the gas barrier property is further deteriorated. On the other hand, a metal vapor-deposited film formed of a foil or a vapor-deposited film using a metal or a metal compound such as Al is less affected by temperature, humidity, etc., and is excellent in gas barrier properties, but can be seen through the contents of the package. It has a drawback that it cannot be confirmed and that it must be disposed of as incombustibles when disposed after use.

Therefore, as a packaging material which overcomes these drawbacks, for example, US Pat.
An inorganic oxide such as silicon oxide, aluminum oxide, and tin oxide as described in -28017 and the like was formed on a polymer plastic substrate by a deposition method such as a vacuum deposition method or a sputtering method. Film is being developed. These films are known to have transparency and gas barrier properties against oxygen, water vapor, etc., and are considered suitable as packaging materials having both transparency and gas barrier properties that cannot be obtained with metal-deposited films. .

[0006]

However, even if the film is suitable for the above-mentioned packaging material, it is hardly used as a packaging container or a packaging material alone as a vapor-deposited film. Are mostly laminated. For example, an extruded laminate polyolefin-based thermoplastic resin is often used in terms of processability and cost.

Therefore, general extrusion conditions (extrusion temperature:
When the laminate is formed at 320 ° C.), the deposited film is damaged by heat at the time of lamination, causing damage such as cracks and scratches,
There is a problem that a gas component such as oxygen and water vapor penetrates from the damaged portion, thereby deteriorating a high barrier property that the vapor deposition film originally should have, and only under a certain limited condition. The extrusion lamination method cannot be used, and there is a practical problem. For example, when the extrusion temperature is 320 ° C., it can be used only when the resin thickness is 15 μm or less.

Accordingly, the present invention provides a film comprising a transparent plastic substrate provided with an evaporation layer made of an inorganic compound.
Even when laminating under general extrusion conditions when laminating a polyolefin-based thermoplastic resin layer by extrusion lamination, a transparent laminate having high practical gas barrier properties that is transparent and does not deteriorate gas barrier properties is provided. The purpose is to do.

[0009]

Means for Solving the Problems The present invention has been made to solve the above problems, and the invention described in claim 1 has a thickness of at least one surface on a transparent polymer resin substrate of 5 to 5 mm.
A transparent laminate having gas barrier properties, wherein a thin film layer made of an inorganic compound having a thickness of 300 nm, a gas barrier coating layer containing at least one of a metal alkoxide hydrolyzate and tin chloride, and an extruded laminate polyolefin-based thermoplastic resin layer are sequentially laminated. It is.

The gas barrier according to claim 1, wherein the hydrolyzate of the metal alkoxide is a hydrolyzate of tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof. It is a transparent laminate having properties.

According to a third aspect of the present invention, the thin film layer made of the inorganic compound is any one of silicon oxide, aluminum oxide, and tin oxide. It is a transparent laminated body which has.

According to a fourth aspect of the present invention, a thin film layer made of an inorganic compound having a thickness of 5 to 300 nm is provided on at least one surface of a substrate made of a transparent polymer plastic material,
Next, a water-soluble polymer and a coating agent mainly composed of (a) an aqueous solution containing at least one of a metal alkoxide and a hydrolyzate thereof, or (b) tin chloride, or a mixed solution of water / alcohol are applied. , A gas-barrier coating excellent in heat resistance formed by heating and drying, and a polyolefin-based thermoplastic resin layer heated and melted in a curtain shape by using an extrusion laminating method, sequentially laminated. It is.

The invention according to claim 5 is the transparent laminate having gas barrier properties according to claim 4, wherein the water-soluble polymer is polyvinyl alcohol.

According to a sixth aspect of the present invention, the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof. Body.

[0015]

According to the layer structure of the present invention, even when the extruded laminated polyolefin-based thermoplastic resin layer is laminated, the gas barrier coating layer fills and reinforces defects such as cracks generated in the thin film layer or micropores, thereby reinforcing the dense structure. Is formed, so that the gas barrier property does not deteriorate.

[0016]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a transparent laminate having gas barrier properties of the present invention.

First, the structure of the transparent laminate 1 having gas barrier properties of the present invention will be described with reference to FIG. Reference numeral 1 denotes a transparent laminate having a gas barrier property. An inorganic compound thin film layer 3, a gas barrier coating layer 4 having excellent heat resistance, and a polyolefin-based thermoplastic resin layer 5 are sequentially formed on the surface of a polymer plastic substrate 2. .

The substrate 2 is a transparent polymer plastic material, and is preferably a transparent film in order to make use of the vapor-deposited thin film layer to be colorless and transparent. For example, polyethylene terephthalate (PET), polyester films such as polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, polyimide films, and the like are used. Either stretched or unstretched may be used, and those having mechanical strength and dimensional stability are preferred. These are processed into a film and used. Particularly, polyethylene terephthalate arbitrarily stretched in the biaxial direction is preferably used. In addition, this base material 2
Various known additives and stabilizers, for example, antistatic agents, UV inhibitors, plasticizers, lubricants, etc. may be used on the surface of the surface, and in order to improve the adhesion to the thin film, Corona treatment, low-temperature plasma treatment, ion bombardment treatment, or chemical treatment, solvent treatment, or the like may be performed.

Although the thickness of the base material 2 is not particularly limited, the thickness of the inorganic compound thin film layer 3 is not limited. Considering this, it can be said that it is practically preferable that the thickness be in the range of 3 to 200 μm and 6 to 30 μm depending on the application.

In consideration of mass productivity, it is desirable to use a long film so that a thin film can be formed continuously.

The inorganic compound thin film layer 3 is made of a deposited film of an inorganic compound such as silicon oxide, aluminum oxide or tin oxide, and may be any material having transparency and gas barrier properties against oxygen and water vapor. However, the thin film layer 3 of the present invention
The material is not limited to inorganic compounds such as silicon oxide and aluminum oxide tin oxide, and any material that meets the above conditions can be used.

The optimum conditions for the thickness of the thin film layer 3 differ depending on the type and constitution of the inorganic compound used.
It is desirable to be within the range of -300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, the entire surface of the substrate 2 may not be a film or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. On the other hand, if the film thickness exceeds 300 nm, flexibility cannot be maintained in the thin film, and the thin film may be cracked by external factors such as bending and pulling after the film is formed. Preferably, it is in the range of 10 to 150 nm.

There are various methods for forming the thin film layer 3 made of an inorganic compound on the transparent polymer plastic substrate 2, and it can be formed by a normal vacuum deposition method.
Other thin film forming methods such as a sputtering method, an ion plating method, and a plasma vapor deposition method (CVD) can also be used. However, in consideration of productivity, the vacuum deposition method is currently the most excellent. The heating means of the vacuum evaporation apparatus by the vacuum evaporation method is preferably an electron beam heating method, a resistance heating method, or an induction heating method. In order to improve the adhesion between the thin film and the substrate and the denseness of the thin film, a plasma assist method is used. It is also possible to use a method or an ion beam assist method. In addition, in order to increase the transparency of the deposited film, reactive deposition in which oxygen gas or the like is blown in the deposition may be used.

The gas-barrier coating layer 4 has excellent heat resistance to mitigate thermal damage, and forms a dense structure by filling and reinforcing defects such as cracks or fine holes generated in the thin film layer 3 due to thermal damage or the like. This is provided to prevent the gas barrier property from deteriorating. In order to achieve this, at least one of a metal alkoxide and a hydrolyzate or tin chloride is formed.

As the formation method, a water-soluble polymer,
(A) an aqueous solution containing at least one of a metal alkoxide and a hydrolyzate or (b) tin chloride, or a coating agent mainly containing a water / alcohol mixed solution, or a water-soluble polymer and tin chloride in an aqueous system ( The inorganic compound thin film layer 3 on the base material 2 is coated with a solution dissolved with a solvent (water or water / alcohol mixture) or a solution obtained by mixing the solution with a metal alkoxide, which has been directly or preliminarily hydrolyzed. Formed by heating and drying.

Each component contained in the coating agent will be described in more detail.

The water-soluble polymer used for the coating agent in the present invention includes polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when polyvinyl alcohol (hereinafter, referred to as PVA) is used for the coating agent of the transparent laminate having gas barrier properties of the present invention, the gas barrier properties are most excellent. The PVA referred to here is generally obtained by saponifying polyvinyl acetate, and has several tens percent of acetic acid groups remaining. That is, complete so-called partially saponified PVA has only a few percent of acetic acid groups remaining.
It includes, but is not particularly limited to, VA.

Tin chloride is stannous chloride (SnCl ₂ ),
Stannic chloride (SnCl ₄ ) or a mixture thereof may be used, and either anhydrous or hydrated can be used.

Further, the metal alkoxide is represented by a general formula such as tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxy aluminum [Al (O-2′-C ₃ H ₇ ) ₃ ], M (OR) _n (M: metal such as Si, Ti, Al, Zr, R: CH ₃ ,
(An alkyl group such as C ₂ H ₅ ). Among them, tetraethoxysilane and triisopropoxyaluminum are preferable because they are relatively stable in an aqueous solvent after hydrolysis.

Each of the above-mentioned components can be added to the coating agent alone or in combination of several components. Further, as long as the gas barrier properties of the coating agent are not impaired, isocyanate compounds, silane coupling agents, dispersants, and stabilizers Known additives such as a viscosity modifier and a coloring agent can be added.

For example, an isocyanate compound added to a coating agent has two or more isocyanate groups (NCO groups) in its molecule. For example, tolylene diisocyanate (hereinafter, TDI), triphenylmethane triisocyanate (hereinafter, TTI) ), Tetramethylxylene diisocyanate (hereinafter, TMXDI), and polymers and derivatives thereof.

As a method for applying the coating agent, conventionally known means such as a commonly used dipping method, roll coating method, screen printing method, spraying method and the like can be used. The thickness of the coating varies depending on the type of coating agent and processing conditions, but the thickness after drying is 0.01μ.
It is sufficient that the thickness is at least m, but if the thickness is at least 50 μm, cracks are likely to occur in the film.

When the method for forming a gas barrier coating layer by the coating method described above is used, not only the metal alkoxide hydrolyzate and tin chloride but also other components such as a solvent are contained in the gas barrier coating layer. It will be included as a component.

It goes without saying that the gas barrier coating layer may be formed by means other than the method described above.

The polyolefin-based thermoplastic resin layer 5 is heated and melted during extrusion lamination, extruded in a curtain shape and bonded to the substrate 2 to function as a heat seal layer, or the substrate 2 and other substrates are bonded to each other. It functions as an adhesive layer when combined, and usually requires extruding the resin at a high temperature in order to obtain adhesive strength.

As the polyolefin-based thermoplastic resin, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, etc. can be used. In general, polyethylene is used from the viewpoint of extrusion processability. Often.

The temperature at which the resin is heated and melted and extruded into a curtain shape varies depending on the resin. For example, when a polyethylene resin is used, the temperature is 290 to 330 ° C.
Is preferably within the range. If it is lower than 290 ° C., the adhesive strength to the substrate 2 is weak, and if it is higher than 330 ° C., there is a problem that the polyodor is serious. Preferably it is in the range of 310 to 320 ° C.

The thickness of the resin layer 5 is not particularly limited, and the optimum thickness varies depending on the type of resin, processing conditions, and the like. A practically used thickness is, for example, in the range of 10 to 60 μm.

The polyolefin thermoplastic resin layer 5
It is also possible to laminate another layer such as a heat seal layer on the substrate. The heat seal layer is used for an adhesive portion when forming a bag-shaped package or the like.
Polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, and their metal crosslinked products Is used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm.
As a forming method, any of known methods such as a method of laminating a film-like material made of the above resin by a dry laminating method, a non-solvent laminating method, an extrusion laminating method in which the resin is heated and melted and extruded into a curtain shape, and laminated. Can be laminated.

The transparent laminate having gas barrier properties of the present invention will be further described with reference to specific examples.

Example 1 Silicon oxide was vapor-deposited to a thickness of about 40 nm on one surface of a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm as a substrate 2 by a vacuum vapor deposition device using a resistance heating method (not shown). An inorganic compound thin film layer 3 was formed. Next, a coating agent having the following composition was applied thereon by a bar coater and dried at 120 ° C. for 1 minute with a drier to form a gas barrier coating layer 4 having a thickness of 0.3 μm. (Composition of coating agent) Mixing ratio of liquid and liquid (wt
%) In a ratio of 60/40. ｛However, 89.6 g of hydrochloric acid (0.1N) is added to 10.4 g of tetraethoxysilane.
And stirred for 30 minutes to hydrolyze the solid content of 3 wt%
The hydrolyzed solution (in terms of SiO ₂ ) is a 3 wt% water / isopropyl alcohol solution of polyvinyl alcohol (90:10 by weight of water: isopropyl alcohol). Further, polyethylene is formed on the gas barrier coating layer 4 by extrusion lamination. 5 was extruded in a curtain shape at an extrusion temperature of 320 ° C. so as to have a thickness of 20 μm, and was simultaneously laminated with an unstretched polypropylene film of 25 μm to obtain a transparent laminate 1 having gas barrier properties of the present invention.

Example 2 A transparent laminate 1 having gas barrier properties of the present invention was obtained in the same manner as in Example 1, except that a low-density polyethylene film 40 μm was used instead of the unstretched polypropylene film 25 μm. .

<Example 3> In the same manner as in Example 1, except that polyethylene 5 was extruded and laminated in a curtain shape at an extrusion temperature of 320 ° C to a thickness of 30 µm using the extrusion laminating method, the same procedure was followed. The transparent laminate 1 having a gas barrier property of was obtained.

Example 4 A transparent laminate 1 having gas barrier properties of the present invention was produced in the same manner as in Example 4, except that the thickness of the polyethylene was changed to 40 μm.

<Example 5> In the same manner as in Example 1, except that aluminum oxide having a thickness of 20 nm was provided as the inorganic compound thin film layer 3 by a vacuum evaporation apparatus using an electron beam heating method (not shown), the present invention was carried out. The transparent laminate 1 having a gas barrier property of was obtained.

<Example 6> In the same manner as in Example 5, except that polyethylene 5 was extruded and laminated in a curtain shape at an extrusion temperature of 320 ° C so as to have a thickness of 30 µm by using an extrusion laminating method, the present invention was repeated. The transparent laminate 1 having a gas barrier property of was obtained.

<Example 7> In the same manner as in Example 1, except that tin oxide having a thickness of 50 nm was provided as the inorganic compound thin film layer 3 by a vacuum evaporation apparatus using an electron beam heating system (not shown), the present invention was carried out. The transparent laminate 1 having a gas barrier property of was obtained.

Comparative Example 1 A transparent laminate was obtained in the same manner as in Example 1 except that the gas barrier coating layer 4 was not provided.

Comparative Example 2 A transparent laminate was obtained in the same manner as in Example 3 except that the gas barrier coating layer 4 was not provided.

Comparative Example 3 A transparent laminated body was obtained in the same manner as in Example 5, except that the gas barrier coating layer 4 was not provided.

Comparative Example 4 A transparent laminate was obtained in the same manner as in Example 6, except that the gas barrier coating layer 4 was not provided.

In order to evaluate the obtained laminate, the water vapor transmission rate (g / m ² / day) and the transparency before and after laminating the polyolefin-based thermoplastic resin layer were measured. Table 1 shows the results.

[0053]

[Table 1]

In comparison with the examples, the comparative examples show a deteriorated barrier property after lamination, but the examples of the transparent laminate having gas barrier properties of the present invention show good values even after lamination. ing.

[0055]

As described above, according to the transparent laminate having gas barrier properties of the present invention, a gas barrier coating excellent in heat resistance is provided on an inorganic compound vapor-deposited layer provided on a polymer base material. So, even after laminating the resin melted at high temperature by extrusion lamination method, the heat damage is reduced,
Further, since the vapor-deposited film has a dense structure, a transparent and highly practical laminate without gas barrier property deterioration can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a transparent laminate having gas barrier properties of the present invention.

[Description of Signs] 1 Transparent laminate having gas barrier properties 2 Polymeric plastic substrate 3 Inorganic compound layer 4 Gas barrier coating layer excellent in heat resistance 5 Potiolefin thermoplastic resin layer

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Yoshihara 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. Examiner Yoko Nakajima (56) References JP 5-131590 (JP, A) JP-A-6-192454 (JP, A) JP-A-6-329821 (JP, A) JP-A-3-63127 (JP, A) JP-A-8-309913 (JP, A) JP-A-7-164591 (JP, A) JP-A-6-134943 (JP, A) JP-A-55-126448 (JP, A) JP-A-55-132242 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) B32B 1/00-35/00

Claims (6)

(57) [Claims] 1. A thin film layer made of an inorganic compound having a thickness of 5 to 300 nm on at least one surface of a transparent polymer resin substrate, a gas barrier coating layer containing at least one of a metal alkoxide hydrolyzate and tin chloride, and an extruded laminate polyolefin-based material. A transparent laminate having gas barrier properties, wherein thermoplastic resin layers are sequentially laminated. 2. The method according to claim 1, wherein the metal alkoxide hydrolyzate is tetraethoxysilane or triisopropoxy aluminum.
The transparent laminate having gas barrier properties according to claim 1, wherein the transparent laminate is a hydrolyzate of a mixture thereof. 3. The transparent laminate having gas barrier properties according to claim 1, wherein the thin film layer made of the inorganic compound is any one of silicon oxide, aluminum oxide and tin oxide. 4. A thin film layer made of an inorganic compound having a thickness of 5 to 300 nm is provided on at least one surface of a substrate made of a transparent polymer plastic material, and then a water-soluble polymer and (a)
One or more metal alkoxides and hydrolysates thereof, or
(B) A gas barrier coating which is coated with an aqueous solution containing at least one of tin chlorides or a water / alcohol mixed solution as a main component and dried by heating, and is further heated and melted in a curtain shape by extrusion lamination. A transparent laminate having gas barrier properties, characterized by sequentially laminating a series of thermoplastic resin layers. 5. The transparent laminate having gas barrier properties according to claim 4, wherein said water-soluble polymer is polyvinyl alcohol. 6. The transparent laminate having gas barrier properties according to claim 4, wherein the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof.