JPH09201897A - Gas barrier olefin resin laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the gas barrier properties, eliminate the peeling of an inorganic oxide thin film at the time of secondary processing or using, and prevent lowering of the decrease in the gas barrier properties by forming an inorganic oxide layer on the upper surface of an olefin resin layer via specific ethylene vinyl alcohol copolymer coating layer. SOLUTION: As olefin resin, propylene resin such as propylene homopolymer, propylene ethylene copolymer can be used. The ethylene vinyl alcohol copolymer for forming the coating layer contains 20 to 50mol% of ethylene and 50 to 80mol% of vinyl alcohol. Normally, the copolymer of ethylene and vinyl acetate is hydrolyzed with alkali such as caustic soda so that saponification degree becomes 90% or more. As the inorganic oxide, the oxide for forming a transparent layer is preferable, and silicon oxide, aluminum oxide, or their mixture is preferable. Thus, excellent gas barrier properties are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an olefin resin laminate excellent in gas barrier property used for protecting foods, electronic parts and the like. In particular, a transparent gas-barrier olefin resin plate can be obtained.

[0002]

2. Description of the Related Art It has been proposed to wrap foods, electronic industrial parts and the like in a film or a container to suppress oxygen permeation to prevent oxidation of the contents and maintain quality for a long time. For example, Japanese Patent Publication No. 53-12953, JP-A-4-3535.
No. 32 discloses a general formula SixOy (x = 1, 2, on at least one surface of a flexible plastic film such as polyethylene terephthalate, cellophane, nylon, polypropylene, or polyethylene having a thickness of 5 to 300 μm.
thickness of a silicon compound having a composition of y = 0, 1, 2, 3) 10
A transparent flexible plastic film having a high degree of air permeation prevention and moisture permeation prevention provided with a transparent thin film layer of 0 to 3000 angstrom is disclosed.

Further, in Japanese Patent Laid-Open No. 63-23794, a metal oxide of one kind of metal selected from the group consisting of In, Sn, Zn, Zr and Ti is provided on at least one surface of the flexible plastic film. Is disclosed by sputtering, and a transparent heat-sealing resin film is coated on the transparent gas barrier film.

When the film material is a material having a polar group such as polyethylene terephthalate, nylon and cellophane, the film and the inorganic oxide film have sufficient adhesion and a good gas barrier property. However, even if a vapor-deposited film made of the above inorganic oxide is formed on the surface of a polyolefin film having no polar group such as polypropylene and polyethylene, a stable gas barrier property that can be practically used cannot be obtained. That is, since the adhesion between the polyolefin film and the inorganic oxide thin film is weak, when laminating a heat-sealable resin having a melting point lower than the melting point of the polyolefin, or using this laminate, the secondary of bag making and lid sealing When processing, using these bags, filling the contents in the container, and further sterilizing the retort, external stress and heat are applied to the molded product and the inorganic oxide thin film peels from the polyolefin molded product, and the gas barrier However, there is a problem in that it cannot be put to practical use.

Further, in JP-A-7-126419, a water-soluble polymer such as polyvinyl alcohol and one or more metal alkoxides or hydrates thereof, or tin chloride are formed on a substrate made of a polymer resin composition. Disclosed is a gas barrier laminate having a vapor deposition layer made of an inorganic compound on a coating layer obtained by applying a coating agent containing an aqueous solution containing at least one of the above or a water / alcohol mixed solution as a main component and heating and drying the coating agent. ing.

In this case, when the polymer resin composition is a resin having a polar group such as polyethylene terephthalate or nylon, the film and the coating layer have high affinity and sufficient adhesion, but the polyolefin-based resin composition When it is a resin, it has low affinity with the coating layer and insufficient adhesion, and cannot be put to practical use. That is, since the adhesion between the polyolefin film and the coating layer is low, when this film is laminated and used as a packaging material, peeling easily occurs at this interface, which is not practical and on the coating layer. This causes the occurrence of cracks in the inorganic compound, and there is a problem that the gas barrier property deteriorates. Further, since a water-soluble polymer is used, the water resistance is poor and there is a problem that it cannot withstand boil or retort treatment.

[0007]

DISCLOSURE OF THE INVENTION The present invention is an olefin resin laminate having an inorganic oxide thin film laminated thereon, which is excellent in gas barrier properties, and the inorganic oxide thin film is not peeled off during secondary processing or use thereof. An object of the present invention is to provide an olefin resin laminate which does not deteriorate in gas barrier property.

[0008]

According to the present invention, an ethylene content of 20 to 50 mol% is provided on the upper surface of an olefin resin layer.
It is intended to provide an olefin resin laminate having a gas barrier property, in which an inorganic oxide layer is formed through a coating layer of an ethylene / vinyl alcohol copolymer having a saponification degree of 90% or more.

[0009]

[Function] A good gas barrier property is obtained by combining an ethylene / vinyl alcohol copolymer and an inorganic oxide, and the presence of an alcoholic hydroxyl group in the ethylene / vinyl alcohol copolymer causes the base material and the inorganic oxide layer to be separated. It is possible to obtain an olefin-based resin laminate having a dense inorganic oxide layer that has more tight adhesion and fewer defects. Also, by providing the ethylene / vinyl alcohol copolymer layer by coating, the surface becomes smooth and the inorganic oxide layers are uniformly and densely laminated, so that good gas barrier properties can be obtained even if the thickness is thin. Further, it is possible to obtain an olefin-based resin laminate in which the gas barrier property is not deteriorated even by an external force.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Olefin Resin An olefin resin forming an olefin resin layer is a propylene homopolymer, a propylene / ethylene copolymer, a propylene / butene-1 copolymer, a propylene / 4 polymer.
-Propylene-based resin such as methylpentene-1 copolymer,
Ethylene resin such as linear-polyethylene, or
An olefin resin modified with α, β-unsaturated carboxylic acid can be used. These may be used as a mixture of two or more kinds, or may be used by being laminated, and may be stretched in one direction or in two directions. Further, it may contain an anti-blocking agent, a nucleating agent, a stabilizer, a lubricant and the like.

In addition, ethylene.
The side on which the vinyl alcohol copolymer layer is provided may be subjected to surface treatment such as corona treatment, ozone treatment, glow discharge treatment, plasma treatment and flame treatment. Although the addition of a pigment or a filler is not excluded from the olefin resin layer, it is generally used as a transparent plate.

The thickness of the olefin resin layer is not particularly limited, but generally 5 to 1000 μm, preferably 10
It is a plate-like body composed of a film or a sheet of ˜500 μm, particularly preferably 15-200 μm. Furthermore, a plate-shaped body made of an olefin resin may be subjected to secondary processing by vacuum forming, pressure forming, or the like.

Coating of ethylene / vinyl alcohol copolymer
The ethylene / vinyl alcohol copolymer forming the cloth layer coating layer contains 20 to 50 mol% of ethylene, preferably 25 to 3 ethylene.
5 mol%, vinyl alcohol 50 to 80 mol%, preferably 65 to 75 mol% of the copolymer, usually,
A copolymer of ethylene and vinyl acetate (50 to 80 mol%) has a saponification degree of 9 with an alkali such as caustic soda and caustic potash.
It is obtained by hydrolysis so as to be 0% or more, preferably 96 to 100%. If the proportion of vinyl alcohol in the copolymer is less than 50 mol%, the adhesive force with the inorganic oxide layer is insufficient. On the other hand, if it exceeds 80 mol%, the processability such as stretchability is impaired.

The coating solution of ethylene / vinyl alcohol copolymer is prepared by dissolving the ethylene / vinyl alcohol copolymer in a solvent such as water, alcohol or a mixed solvent of water and alcohol. Preferred is a mixed solvent of water and ethyl alcohol, isopropyl alcohol, or the like. The ethylene-vinyl alcohol copolymer of the coating solution can be dissolved and used so that the resin solid content concentration is 5 to 50% by weight. Further, the viscosity of the coating solution is 20 ° C.
5,000 centipoise at 40 ° C, 300-600
0 centipoise (B type viscometer) is preferable. As a method for applying the coating liquid to the olefin resin layer, spraying, or a known coating method, for example, a gravure roll method,
The inverse roll method, the reverse roll method, the air knife coating method, and the metering bar coating method can be adopted.

The coating solution is preferably heated to 60 to 100 ° C. before use. If the temperature is lower than 60 ° C, it is difficult to maintain the proper viscosity of the coating liquid, and it tends to be difficult to obtain a uniform coating. If the temperature exceeds 100 ° C, the solvent of the coating liquid evaporates and the viscosity becomes too high, which makes uniform coating difficult. Tends to become.

The laminate coated with the ethylene / vinyl alcohol copolymer is stretched in one direction or in two directions as needed. The stretching ratio is generally 3 times or more, preferably 5 times or more in one direction. Furthermore, the surface may be subjected to surface treatment such as corona treatment, ozone treatment, glow discharge treatment, plasma treatment, and flame treatment. The thickness of the coating layer of ethylene / vinyl alcohol copolymer is preferably 0.
03-5 μm, more preferably 0.05-1.0 μm
It is. When the thickness of the coating layer of ethylene / vinyl alcohol copolymer is less than 0.03 μm, the effect is poor, and conversely,
If it exceeds 5 μm, the gas barrier performance is improved, but the humidity dependency becomes large, and it is not economically preferable.

Inorganic Oxide Layer The inorganic oxide of the present invention is preferably one that forms a transparent inorganic oxide layer, such as silicon, aluminum, titanium,
Examples thereof include oxides of tin, zinc, magnesium, indium and the like, and one of these may be used, or a mixture of two or more thereof may be used. Preferably, silicon oxide, aluminum oxide, or a mixture thereof is used. The thickness of the inorganic oxide layer is preferably 4 to 500 nm, more preferably 7 to 300 nm.

Further, the thickness of the inorganic oxide layer relative to the thickness of the ethylene / vinyl alcohol copolymer layer is 0.1 in terms of the thickness ratio of the inorganic oxide layer / the coating layer of the ethylene / vinyl alcohol copolymer. 003 to 1 is preferable, and more preferably 0.
It is in the range of 01 to 0.8. When out of this range,
Peeling and cracking are likely to occur and sufficient gas barrier properties cannot be obtained.

The type and thickness of the inorganic oxide layer are appropriately selected in view of transparency, vapor deposition rate, gas barrier property, film winding property and the like. As a method of forming the inorganic oxide layer,
Molded product under vacuum (1 x
Method of depositing an inorganic oxide at 10 ⁻⁴ to 1 × 10 ⁻¹ Pa) (Japanese Patent Publication No. 53-12963); organic silicon compounds, oxygen and an inert gas which have been evacuated in a vapor deposition machine which has been evacuated and evacuated in advance. A method of generating plasma by a magnetron glow discharge containing a gas stream to deposit SiOx on a molded article in the vapor deposition machine (Japanese Patent Laid-Open No. 64-87772, USP).
4,557,946, USP 4,599,678)
And the like. Further, industrial materials published in November 1990, Volume 38, No. 14, pp. 104 to 105, are classified as an ion plating method, a high frequency plasma CVD method, an electron beam (EB) vapor deposition method, and a sputtering method, The principle has been introduced and these methods can be used.

Resin Laminate The thickness of the resin laminate is not particularly limited, but generally 5 to 10
The thickness is 00 μm, preferably 10 to 500 μm, and particularly preferably 15 to 200 μm. Further, a thermoplastic resin film or the like can be laminated on one side or both sides of the gas barrier olefin resin laminate of the present invention, if necessary.

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not particularly limited thereby. Example 1 Polypropylene (MFR 2.3 g / 10 min) resin was melted in an extruder and extruded into a sheet shape from a T die to obtain an unstretched sheet. This unstretched sheet was stretched 5 times at a temperature of 130 ° C. by a longitudinal stretching machine composed of heating rolls having different peripheral speeds, and then the longitudinally stretched sheet was heated to 90 ° C. by a heating roll to give one side. Was subjected to a corona discharge treatment. Next, ethylene (29 mol%) / vinyl alcohol (71 mol%) random copolymer resin (Soarnol 30L (trade name) manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) heated to 80 ° C .; melting point 1
88 ° C.) The coating solution (resin concentration 30% by weight) is coated on the corona discharge treated surface with a metalling bar coater to a wet film thickness of 15 μm, introduced into a tenter through a conveying roller, and then horizontally transferred at 165 ° C. 10 times in one direction, 1
The film is heat-set at 60 ° C., the coated surface of the film is subjected to heating corona treatment, and an ethylene / vinyl alcohol resin coating film having a thickness of 20 μm (coat layer 0.
45 μm) was obtained. This film was placed in a plasma vapor deposition device (BP-1; Samco International Laboratories), and the pressure inside the device was reduced to 1.33 × 10 ⁻⁴ Pa, then 3 parts by volume of hexamethyldisiloxane and 3 volumes of oxygen. Part, and mixed gas of 20 parts by volume of helium were introduced, glow discharge was performed from an unbalanced type magnetron to generate plasma, and a SiO ₂ layer (thickness 50 nm) was formed on the ethylene / vinyl alcohol resin coating layer side. The oxygen permeability of this film was measured.

Example 2 A polypropylene (MFR 2.3 g / 10 min) resin and a maleic anhydride (0.35% by weight) graft polypropylene (“Modic MFS-3” manufactured by Mitsubishi Chemical Co., Ltd.) were separately prepared as adhesive resins. The melted material in the extruder is fed to one die and layered in the die and extruded to give 20μ
m two-layer film (layer constitution, polypropylene / adhesive resin = 19 μm / 1 μm) was obtained. Corona discharge treatment was applied to the obtained adhesive resin side, and the same ethylene / vinyl alcohol random copolymer resin coating solution as in Example 1 was applied to the corona discharge treated surface with a gravure roll (100 mesh). The coated surface of this film was subjected to a heating corona treatment to obtain an ethylene / vinyl alcohol resin coating film (coat layer 0.6 μm). A SiO ₂ layer (thickness: 50 nm) was formed on this film in the same manner as in Example 1. The oxygen transmission rate of this film was measured.

Example 3 An ethylene / vinyl alcohol resin coating film (coat layer 0.45 μm) obtained in the same manner as in Example 1 was obtained.
On the surface coated with ethylene / vinyl alcohol resin of m), Al was evaporated as a vapor deposition material by an electron beam heating system using a vacuum vapor deposition apparatus, and oxygen gas was further introduced to the pressure 2
An aluminum oxide layer was formed under the condition of × 10 ^-2 Pa. The oxygen transmission rate of this film was measured.

Comparative Example 1 Polypropylene (MFR 2.3 g / 10 min) resin and an adhesive resin, maleic anhydride (0.35% by weight) graft polypropylene ("Modic MFS-3" manufactured by Mitsubishi Chemical Corporation), ethylene ( 29 mol%) / vinyl alcohol (71 mol%) random copolymer resin (melting point 18
What melt | dissolved 8 degreeC) with a separate extruder was supplied to one die, it piled up in a layer within a die, and it extruded, and the 20-micrometer three-layer film was obtained. The layer structure of this film is polypropylene / adhesive resin / ethylene vinyl alcohol resin,
They are 15 μm / 1 μm / 4 μm, respectively. The ethylene / vinyl alcohol resin side of the obtained film was subjected to corona treatment, and the corona-treated surface was treated with Si in the same manner as in Example 1.
An O ₂ layer was formed and the oxygen transmission rate was measured.

Comparative Example 2 A biaxially stretched film was produced in the same manner as in Example 1 except that the ethylene / vinyl alcohol copolymer resin coating solution was not applied and the corona discharge treatment in the previous stage was not performed.
A SiO ₂ layer (thickness: 80 nm) was formed and the oxygen permeability was measured. Comparative Example 3 A biaxially stretched film was produced in the same manner as in Example 1 except that the SiO ₂ layer was not formed on the biaxially stretched film,
The oxygen permeability was measured.

Comparative Example 4 A coating liquid of ethylene / vinyl alcohol copolymer resin was applied.
Other than not having and not performing corona discharge treatment in the previous stage
Produced a biaxially stretched film in the same manner as in Example 1,
Form an aluminum oxide layer and measure the oxygen transmission rate.
Was. Comparative Example 5 Polyvinyl chloride was used in place of the ethylene / vinyl alcohol copolymer resin.
Example 1 except that nyl alcohol (PVA) was used.
Similarly, a biaxially stretched film is manufactured, and _TwoShape layers
Then, the oxygen permeability was measured.

Evaluation (1) Change with respect to secondary processing The inorganic oxide layer surface or the corona discharge treated surface of the biaxially stretched films obtained in Examples 1, 2 and 3 and Comparative Examples 1, 2, 3, 4, and 5. Using a laminator device, MFR is 5g
/ 10 minutes, low density polyethylene having a density of 0.922 g / cm ³ was extruded from a T-die at 320 ° C. into a film having a thickness of 20 μm and laminated. The oxygen transmission rate of this laminate is shown in Table 1.

(2) Change with respect to external stress The biaxially stretched films obtained in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5 and the laminated film with low density polyethylene were well-known. Using a gelbot tester manufactured by Keiki Co., Ltd., the film was rolled into a tubular shape, both ends of this tube were fixed to a gripping device of the tester, and after repeated ± 90 ° twisting for 10 times, the oxygen permeability was determined. It was measured.
The measured values are shown in Table 1.

[0029]

[Table 1]

[0030]

EFFECT OF THE INVENTION In the olefin resin laminate having the inorganic oxide vapor-deposited according to the present invention, by providing the ethylene / vinyl alcohol copolymer layer by coating, the surface becomes smooth and the inorganic oxide layer becomes uniform and Since they are densely laminated, good gas barrier properties can be obtained even if the thickness is thin, and the gas barrier properties do not deteriorate even when external heat or force is applied during secondary processing or during use. Can be obtained.

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Claims (6)

[Claims] 1. An inorganic oxide layer is formed on the upper surface of an olefin resin layer through a coating layer of an ethylene / vinyl alcohol copolymer having an ethylene content of 20 to 50 mol% and a saponification degree of 90% or more. , Gas barrier olefin resin laminate. 2. The gas-barrier olein-based resin laminate according to claim 1, wherein the laminate is a plate-like body. 3. The gas barrier olefin resin laminate according to claim 1, wherein the olefin resin layer is biaxially stretched. 4. The ethylene / vinyl alcohol copolymer has an ethylene content of 25 to 35 mol%, and a saponification degree of 9
The gas barrier olefin resin laminate according to claim 1, which is 6 to 100%. 5. The thickness of the olefin resin layer is 10 to 50.
0 μm, the thickness of the ethylene / vinyl alcohol copolymer coating layer is 0.03 to 5.0 μm, the thickness of the inorganic oxide layer is 4 to 500 nm, and the inorganic oxide layer / ethylene / vinyl alcohol layer is coated. The gas barrier olefin resin laminate according to claim 1, wherein the layer thickness ratio is 0.003 to 1. 6. An ethylene / vinyl alcohol copolymer coating layer is formed by coating an ethylene / vinyl alcohol copolymer dissolved in a mixed solvent of water and alcohol. The gas barrier olefin resin laminate described.