JPH08164595A - Transparent laminated film - Google Patents

Abstract

PURPOSE: To obtain a laminated film having high transparency, gas barrier performance, and adhesion by laminating a resin layer of a mixture of a polyester and an epoxy compound and a metal oxide layer with a specified thickness in sequence on one side of a polymer base material. CONSTITUTION: In a transparent laminated film 1 in which a resin layer 3 of a mixture of polyester and an epoxy compound and a thin film layer 4 of a metal oxide with thickness of 30-300nm are laminated in sequence on one side of a transparent polymer base material 2. A printing method such as offset, gravure, and silk screen printing method and an application method such as a roller coating method are used as a method to form the resin layer 3. The thin film layer 4 is made of a vapor deposition film of a metal oxide such as silicon oxide, aluminum oxide, and tin oxide and has transparency and gas barrier performance to oxygen and water vapor.

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 foods, pharmaceuticals, precision electronic parts and the like, and more particularly to a packaging film excellent in transparency, barrier property and adhesion.

[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, particularly oxidation and deterioration of proteins and fats and oils in foods, and further improve taste and freshness. In order to retain the product, in pharmaceuticals that require aseptic handling, it suppresses the deterioration of the active ingredient, and in order to maintain its efficacy, it also prevents corrosion and poor insulation of metal parts in precision electronic components. Therefore, it is necessary to prevent the influence of oxygen, water vapor, and other gases that change the contents of the packaging material, and it is required to have a gas barrier property for blocking these gases.

Therefore, polymer resins such as polypropylene (KOP) coated with vinylidene chloride resin, polyethylene terephthalate (KPET), ethylene vinyl alcohol copolymer (EVOH), etc., which are generally said to have relatively high gas barrier properties, have been conventionally used. A packaging film using the composition as a gas barrier material for a packaging material, a metal foil made of a metal such as Al, a suitable polymer resin composition (even by itself, even if the resin does not have a high gas barrier property)
A packaging film using a metal deposition film obtained by depositing a metal such as Al or a metal compound as a packaging material has been generally used.

However, the packaging film using only the above-mentioned polymer resin composition is not only inferior in gas barrier property to a foil using a metal or a metal compound such as Al or a metal vapor deposition film formed with a vapor deposition film. However, it is easily affected by temperature and humidity, and depending on the change, the gas barrier property is further deteriorated. On the other hand, a foil using a metal such as Al or a metal compound or a metal vapor-deposited film on which a vapor-deposited film is formed is less affected by temperature and humidity and has excellent gas barrier properties, but the contents of the package can be seen through. It had a drawback that it could not be confirmed and that it must be treated as an incombustible material when it is discarded after use.

Therefore, as a packaging material that overcomes these drawbacks, for example, US Pat.
No. 28017, etc., an inorganic oxide such as silicon oxide, aluminum oxide, tin oxide, etc. is formed on a polymer film by a vapor deposition method or a sputtering method to form a vapor deposition film. Being developed. These films are known to have transparency and gas barrier properties against oxygen, water vapor, etc., and are suitable as packaging materials having both transparency and gas barrier properties that cannot be obtained with metal vapor deposition films. .

[0006]

However, since the metal oxide vapor-deposited film has a physical bond between the vapor-deposited film and the transparent polymer substrate, the bond strength is weak, especially under high humidity. The adhesion strength may be extremely deteriorated depending on the boil, the retort treatment, and the type of contents.

That is, as the conditions for use as a packaging film, the transparency is such that the contents themselves can be seen through, the high barrier property for blocking the gas etc. that affects the contents, the high humidity and the contents. There is a demand for a film having high adhesion that does not deteriorate due to the attack of a product, and at present, a packaging film satisfying all of these has not been found.

Therefore, an object of the present invention is to provide a transparent laminated film having excellent transparency, high gas barrier properties and further high adhesion.

[0009]

The present invention has been made to solve the above problems, and the invention described in claim 1 is such that at least one surface of a substrate made of a polymer material having transparency is The transparent laminated film is characterized in that a resin layer made of a mixture of polyester and an epoxy compound and a metal oxide layer having a thickness of 30 to 300 nm are sequentially laminated.

A second aspect of the present invention is a transparent laminated film according to the first aspect of the invention, wherein the metal oxide layer is silicon oxide, aluminum oxide, or tin oxide.

[0011]

According to the transparent laminated film of the present invention, a transparent metal having excellent gas barrier properties is provided through a resin layer made of a mixture of polyester and an epoxy compound having excellent adhesion to a substrate made of a transparent polymer material. As it has an oxide layer, it is transparent and has excellent gas barrier properties, and its adhesion strength does not deteriorate even under high humidity.
Strength deterioration after retort treatment can also be suppressed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating the transparent laminated film of the present invention.

First, the structure of the transparent laminated film 1 of the present invention will be described with reference to FIG. Transparent laminated film 1
The resin layer 3 made of polyester and epoxy compound and the thin film layer 4 made of metal oxide are sequentially formed on the surface of the substrate 2.

The above-mentioned substrate 2 is a polymer material having transparency, and a transparent film is preferable in order to make the thin film layer 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, etc. are used, It may be stretched or unstretched, and one having mechanical strength and dimensional stability is preferable. These are processed into a film and used. Particularly, polyethylene terephthalate arbitrarily stretched in the biaxial direction is preferably used. In addition, various well-known additives and stabilizers such as antistatic agents, anti-UV agents, plasticizers and lubricants may be used on the surface of the base material 2 in order to improve the adhesion to the thin film. In addition, corona treatment, low temperature plasma treatment, ion bombardment treatment may be performed as pretreatment, and chemical treatment, solvent treatment and the like may be further performed.

The thickness of the base material 2 is not particularly limited, but it is suitable as a packaging material, may be laminated with other layers, and may be processed when the resin layer 3 and the thin film layer 4 are formed. In consideration of the properties, it can be said that the thickness is practically in the range of 3 to 200 μm, and preferably 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 continuously formed.

The resin layer 3 is provided for the purpose of enhancing the adhesion between the base material 2 and the thin film layer 4, and it is necessary to form the resin layer 3 with a mixture of polyester and an epoxy compound in order to achieve the above purpose. There is. By using this resin, not only the physical bonding force between the base material and the thin film but also the chemical bonding force is added, so that the adhesiveness between them is enhanced.

The polyester resin is terephthalic acid,
Acid raw materials such as isophthalic acid, phthalic acid, methylphthalic acid, trimellitic acid, pyromellitic acid, adipic acid, succinic acid, maleic acid, fumaric acid and their reactive derivatives, and ethylene glycol, propylene glycol, butanediol, hexane Those manufactured by a known method from alcohol raw materials such as diol, diethylene glycol, dipropylene glycol, neopentyl glycol, and isopentyl glycol can be used, but the composition and the like are not particularly limited thereto.

As the epoxy compound, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, glycine ester type epoxy resin, polyether type epoxy resin,
Urethane-modified epoxy resin, methyl-substituted epoxy resin, hydrogenated bisphenol epoxy resin and the like can be used.

The mixing ratio of the two is polyester 5
It is preferable that the ratio is 0 to 95% and the epoxy compound is 50 to 5%. If the polyester resin content is less than 50% and the epoxy compound content is more than 50%, the proportion of epoxy groups that react with the polyol portion of the polyester becomes supersaturated, which is not preferable. The number of epoxy groups that react with the polyol portion of the above is reduced, and curing is poor, which is not preferable. A particularly preferable compounding ratio is 30% of epoxy compound to 70% of polyester.

Additives such as a curing accelerator, an antioxidant, a leveling agent, a flow regulator, a catalyst, etc. may be added to the mixed resin.
It does not matter even if an appropriate amount of a crosslinking reaction accelerator, a filler or the like is added.

The thickness of the resin layer 3 is not particularly limited as long as the resin layer 3 can be uniformly coated, and optimum conditions vary depending on the composition and blending ratio of the mixed resin. However, 1.0μ
If it is thicker than m, there is a problem such as residual solvent, which is not preferable. It is preferably between 0.1 and 0.5 μm. As a method of forming the resin layer 3, for example, a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a known coating method such as roll coating, knife edge coating, and gravure coating can be used. .

The thin film layer 4 is made of a vapor deposited film of a metal oxide such as silicon oxide, aluminum oxide or tin oxide, and may be transparent and have gas barrier properties against oxygen, water vapor and the like. However, the thin film layer 4 of the present invention is not limited to metal oxides such as silicon oxide, aluminum oxide, and tin oxide, and any material that meets the above conditions can be used.

The optimum thickness of the thin film layer 4 varies depending on the type and composition of the metal oxide used, but is generally 3
It is desirable to be in the range of 0 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 30 nm, the entire surface of the resin layer 3 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 fulfilled. Further, if the film thickness exceeds 300 nm, the thin film cannot retain flexibility, and cracks may occur in the thin film due to external factors such as bending and pulling after the film formation.
It is preferably in the range of 40 to 150 nm.

There are various methods for forming the thin film layer 4 made of a metal oxide on the resin layer 3. The thin film layer 4 can be formed by an ordinary vacuum deposition method, but other thin film forming methods such as a sputtering method and an ion plating method. The Ting method or the like can also be used. However, in view of productivity, the vacuum vapor deposition method is the best at the present time. It is preferable to use an electron beam heating method or a resistance heating method as the heating means of the vacuum evaporation apparatus by the vacuum evaporation method. In order to improve the adhesion between the thin film and the base material and the denseness of the thin film, a plasma assist method or an ion beam method is used. It is also possible to use the assist method.

Further, another layer can be laminated on the metal oxide thin film layer 4. For example, a print layer and a heat seal layer. The printing layer is formed for practical use as a packaging bag, and various pigments are used for ink binder resins that have been conventionally used such as urethane-based, acrylic-based, nitrocellulose-based, rubber-based, and vinyl chloride-based. A layer composed of an ink to which an extender pigment and additives such as a plasticizer, a desiccant and a stabilizer are added,
Letters, patterns, etc. are formed. As a forming method, for example, a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method or the like, or a known coating method such as a roll coating, a knife edge coating or a gravure coating can be used. The thickness may be 0.1 to 2.0 μm.

The heat-sealing layer is used as an adhesive portion when forming a bag-like package, and includes polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene. A resin such as a methacrylic acid ester copolymer, an ethylene-acrylic acid copolymer, an ethylene-acrylic acid ester copolymer and a metal cross-linked product thereof is used. Although the thickness is determined according to the purpose, it is generally in the range of 15 to 200 μm. As a forming method, any of known methods such as a dry laminating method of laminating a film made of the above resin by a non-solvent laminating method, an extrusion laminating method in which the above resin is melted by heating and extruded in a curtain shape, and laminated Can be laminated by.

The transparent laminated film of the present invention will be further described with reference to specific examples.

Example 1 As a base material 2, biaxially oriented polyethylene terephthalate (PET) having a thickness of 12 μm was coated on one side with a resin having a polyester / epoxy compound ratio of 70/30 by a gravure coating method to give a thickness of 0. A resin layer 3 having a thickness of 1 μm was formed. Furthermore, by a vacuum vapor deposition device by a resistance heating method (not shown) on the resin layer,
Silicon oxide was vapor-deposited to a thickness of about 40 nm to vapor-deposit the metal oxide layer 4 to produce a transparent laminated film 1.

Table 1 shows the results of measuring the water vapor transmission rate (gr / m ² / day) and the transparency of the produced transparent laminated film 1.

Further, this transparent laminated film 1 was dry laminated with polyethylene having a thickness of 60 μm via a two-component curing type urethane adhesive to obtain a laminated body. A packaging bag was prepared from the obtained laminated body by a four-side seal bag-making machine, and a perm solution was filled as a content and stored in an atmosphere of 40 ° C. and 20% RH.

The water vapor permeability (gr / m ² / day) and laminate strength (gr / 15 mm) of the obtained laminate before and after filling and storing the contents were measured, and the results are shown in Table 1. However,
The measurement result after storage is the value after storage for 1 month.

Example 2 A transparent laminated film 1 was prepared in the same manner as in Example 1 except that the resin layer 3 had a thickness of 0.3 μm.
Was prepared and evaluated in the same manner. Table 1 shows the results.

Example 3 A transparent laminated film 1 was prepared in the same manner as in Example 1 except that the ratio of the mixture was 60/40, and evaluated in the same manner. Table 1 shows the results.

Example 4 A transparent laminated film 1 was prepared in the same manner as in Example 1 except that the mixture ratio was changed to 80/20, and evaluated in the same manner. Table 1 shows the results.

Example 5 A transparent laminated film 1 was prepared and evaluated in the same manner as in Example 1 except that aluminum oxide having a thickness of 20 nm was formed as the thin film layer 4 by an electron beam heating method (not shown). Table 1 shows the results.

Example 6 A transparent laminated film 1 was produced in the same manner as in Example 1 except that tin oxide having a thickness of 40 nm was formed as the thin film layer 4 by an electron beam heating method not shown,
It evaluated similarly. Table 1 shows the results.

Comparative Example 1 A laminated film was prepared in the same manner as in Example 1 except that the resin layer of the mixture was not formed, and evaluated in the same manner. Table 1 shows the results.

Comparative Example 2 A laminated film was prepared in the same manner as in Example 5 except that the resin layer of the mixture was not formed, and evaluated in the same manner. Table 1 shows the results.

Comparative Example 3 A laminated film was prepared in the same manner as in Example 6 except that the resin layer of the mixture was not formed, and evaluated in the same manner. Table 1 shows the results.

[0041]

[Table 1]

In contrast to the Examples, the Comparative Examples are transparent enough to see through the contents themselves, which is the condition used as the packaging film described above, and have a high level of blocking the gas or the like that affects the contents. There is nothing that satisfies all the barrier properties and high adhesion that does not deteriorate due to high humidity or attack of contents, and the transparent laminated film of the present invention satisfies all.

[0043]

As described above, according to the present invention, a transparent and gas-barrier property is provided through a resin layer made of a mixture of a polyester and an epoxy compound, which has excellent adhesiveness due to a chemical bond, to a substrate made of a transparent polymer. Since it has a structure that forms a metal oxide layer with excellent heat resistance, it does not impair the transparency and gas barrier properties of the metal oxide thin film, and the adhesiveness does not deteriorate due to high humidity or contents. A highly transparent laminated film is obtained.

[0044]

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a transparent laminated film of the present invention.

[Explanation of symbols]

 1 Transparent Laminated Film 2 Base Material 3 Resin Layer 4 Thin Film Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C08L 67/00 LPC

Claims (2)

[Claims] 1. A resin layer made of a mixture of polyester and an epoxy compound and a metal oxide layer having a thickness of 30 to 300 nm are sequentially laminated on at least one surface of a base material made of a polymer material having transparency. A transparent laminated film. 2. The transparent laminated film according to claim 1, wherein the metal oxide layer is silicon oxide, aluminum oxide, or tin oxide.