JPH0399842A - Gas interceptive material - Google Patents

Abstract

PURPOSE:To maintain excellent gas interceptive properties even under high humidity and under external mechanical forces, by providing a thin film of a metallic oxide on the surface of a film of an ethylene-vinyl alcohol copolymer resin which is obtained by saponifying a copolymer of ethylene, vinyl acetated and a vinylsilane compound and which has specified values of vinyl acetate component and ethylene content. CONSTITUTION:A saponified silane-containing ethylene-vinyl acetate copolymer (Si-EVOH) obtained by saponifying a copolymer of ethylene, vinyl acetate and a vinylsilane compound has a silane content of 0.0005-0.2 mol%, an ethylene content of 25-60 mol% and a saponification degree of vinyl acetate component of 95-96%. A thin film of a metallic oxide is provided on the surface of an Si-EVOH resin film, whereby a material is obtained which has excellent gas interceptive properties even under high humidity, and maintains the excellent gas interceptive properties even under bending, frictional or other mechanical external forces.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a gas barrier material having excellent gas barrier properties even under high humidity conditions.

1. Arashi Nikuoka In recent years, the requirements for gas barrier materials in various applications have become increasingly sophisticated, and research and development has been actively carried out to improve the functionality of various gas (e.g., oxygen) barrier materials. There is. Among various gas barrier materials, ethylene-
It is a well-known fact that vinyl alcohol copolymer resin (hereinafter abbreviated as EVOH resin) is used in a wide range of applications due to its excellent gas barrier properties, but due to the increasing sophistication and diversification of market requirements. It is also true that there are many uses that cannot be addressed.

In the case of EVOH resin, deterioration of gas barrier properties especially under high humidity becomes a problem. In order to solve this problem, it is conceivable to provide a thin film of metal oxide on the surface of the EV○H resin film by vapor deposition, but this method has a fatal defect. That is, when subjected to external mechanical forces such as bending and friction, the modification effect is significantly impaired due to insufficient interlayer adhesion, and in some cases, the effect is almost nil.

This phenomenon is generally observed when plastics are subjected to this type of treatment, and the case of EVOH resin is no exception. In order to improve this defect, physical surface treatments such as sandblasting, which are generally adopted to improve adhesion, and chemical surface treatments such as corona discharge or primer coating were applied to the EV○H resin film, but these treatments were not satisfactory. No gradual improvement effect was observed.

C1 Problems to be Solved by the Invention The present invention has improved the above-mentioned drawbacks, and has excellent gas barrier properties even under high humidity conditions, and is also excellent even when subjected to mechanical external forces such as bending and friction. It is a gas barrier material that maintains gas barrier properties.

In order to improve the deterioration of the gas barrier properties of EVOH resin, especially under high humidity, the present inventors have developed a method of vapor depositing a thin film of metal oxide on the surface of EV○H horse chestnut resin composition. As a result of careful consideration of the method of installing the conventional E
The fatal flaw in this method, which can be seen in the case of VOH, is that the silane-containing saponified ethylene-vinyl acetate copolymer (hereinafter referred to as 5i-EVOH) is obtained by saponifying a copolymer of ethylene, vinyl acetate, and a vinyl silane compound. The present inventors have newly found that improvements can be made by using the following methods (abbreviated as ``)'' and have completed the present invention. It is clear from the Examples and Comparative Examples described later that when a metal oxide thin film is provided on the 5i-EVQH resin film, superior effects can be obtained compared to when an EVOH resin film is used.

The inventors of the present invention have previously discovered that by incorporating a metal oxide into the EVOH resin film, superior effects can be obtained compared to the case where the metal oxide is not included, and a patent application has already been filed for this invention. However, the present invention uses metal oxides as EVs.
A similar effect can be obtained by using an OH fat film in a beef tallow film, and this method is more excellent in that it does not cause problems such as deterioration of haze.

In addition, JP-A-60-144304 discloses a vinyl acetate component copolymerized with an olefinic monomer containing silane, with a saponification degree of 95 mol% or more and an ethylene content of 25 mol to 6 mol%.
A melt molding material called 5i-EVOH is described, which has an olefinic compound content of 0.0005 to 12 mole %, including silane. However, the above-mentioned JP-A-Sho mentions that 5i-EVOH has improved stress cracking resistance, temperature dependence of oxygen and other gas barrier properties, polar solvent resistance, water resistance, etc. 5L-EVOH
By providing a thin film of metal oxide on the surface of the resin film,
There is no description of the fact that it has excellent gas barrier properties even under high humidity conditions, and that it maintains its excellent gas barrier properties even when subjected to mechanical external forces such as bending and friction, and the present invention is based on a completely different idea. This is a novel invention based on

The present invention will be explained in more detail below. In the present invention,
The 5i-EVOH resin film is a 5i-EVOH resin film or sheet, and its thickness is not particularly limited, but is about 5 to 2000 μm, preferably about 5 to 300 μm.

In addition, as vinylsilane compounds, the following (I>,
One or more compounds selected from the compounds represented by (IF) and (I[[) can be suitably used.

[However, here, n is 0 to 1, m is 0 to 2, R1 is a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and R2 is a saturated branched or unbranched alkoxyl having 1 to 40 carbon atoms. The alkoxyl group may have an oxygen-containing substituent, R3 is hydrogen or a methyl group, R4 is hydrogen or a lower alkyl group, R5 is an alkylene group or a chain carbon atom is replaced by oxygen or nitrogen. mutually bonded divalent organic residues, R6 is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group; R7 is an alkoxyl group or an acyloxyl group; may have a substituent containing oxygen or nitrogen. R8 is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and R9 is a lower alkyl group. ] More specifically, R1 is a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or an allyl group having 6 to 6 carbon atoms.
A lower alkyl group having 1 to 5 carbon atoms having an allyl group of ~18, R4 is hydrogen or a lower alkyl group having 1 to 5 carbon atoms, R
5 is an alkylene group having 1 to 5 carbon atoms or a divalent organic residue in which consecutive carbon atoms are bonded to each other by oxygen or nitrogen; R6 is hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms; 6-18 allyl group, or 6-18 carbon atoms
a lower alkyl group having 1 to 5 carbon atoms having an allyl group, R
8 is hydrogen, halogen, lower alkyl group having 1 to 5 carbon atoms,
R9 is an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms, and R9 is a lower alkyl group having 1 to 5 carbon atoms.

The vinylsilane compounds represented by (1) include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyljethoxysilane, vinyldimethylethoxysilane, allyltrimethoxysilane, allyl Methyldimethoxysilane, allyldimethylmethoxysilane, allyltriethoxysilane, allylmethyljethoxysilane, allyldimethylethoxysilane, vinyltris(β-methoxyethoxy)silane, vinylisobutyldimethoxysilane, vinylethyldimethoxysilane, vinyltributoxysilane, vinyl Methoxydibutoxysilane, vinyldimethoxybutoxysilane, vinyltrihexyloxysilane, vinylditoxydihexyloxylane, vinyldimethoxyhexyloxysilane, vinyltrioctyloxysilane, vinylmethoxydibutoxysilane,
Examples include vinyldimethoxyoctyloxysilane, vinylmethoxydibutoxysilane, vinyldimethoxyoctyloxysilane, vinylmethoxydio-leyloxysilane, vinyldimethoxyoctyloxysilane, and vinyltrimethoxysilane is preferred from an economical standpoint.

As a vinylsilane compound represented by (ffl>,
3-(meth)acrylamidopropyltrimethoxysilane, 3-(meth)acrylamidopropyltriethoxysilane, 3-(meth)acrylamidopropyltris(
β-methoxyethoxy)silane, 3-(meth)acrylamidopropyltris(N-methylaminoethoxy)silane, 2-(meth)acrylamidoethyltrimethoxysilane, (meth)acrylamidomethyltrimethoxysilane, 2-(meth)acrylamide -2-methylpro and lutrimethoxysilane, 2-(meth)acrylamidopropyltrimethoxysilane, N-(2-(meth)acrylamidoethyl)-aminopropyltrimethoxysilane, (3-(meth)acrylamidopropyl)-oxypropyl Trimethoxysilane, 3-(meth)acrylamidopropyltriacetoxysilane, 2-(meth)acrylamidoethyltriacetoxysilane, 4-(meth)acrylamidobutyltriacetoxysilane, 3-(meth)acrylamidopropyltripropionyloxysilane, 2 -(meth)acrylamido-2-methylpro-triacetoxysilane, N-(2-(meth)acrylamidoethyl)aminopropyltriacetoxysilane, 3-
(meth)acryla, midopropylisobutyldimethoxysilane, 2-(meth)acrylamidoethyldimethylmethoxysilane, 3-(meth)acrylamidopropyloctyldiacetoxysilane, (meth)acrylamidomethylphenyldiacetoxysilane, 3-(meth)acrylamidomethylphenyldiacetoxysilane Acrylamidopropylbenzyljethoxysilane, 3-(
N-methyl-(meth)acrylamido)-propyltrimethoxysilane, 2-(N-ethyl-(meth)acrylamido)-ethyltriacetoxysilane, 2-(meth)
Examples include acrylamide-2-methylpropyl monochlorodimethoxysilane, 2-(meth)acrylamido-2-methylpropylmonohydrodiene dimethoxysilane, etc., but economically speaking, 3-(meth)acrylamidopropyltrimethoxysilane and 3-( Meth)acrylamidopropyltriacetoxysilane is preferred, and 2-(meth)acrylamido-2-methylprotrimethoxysilane and 2-meth)acrylamido-2-methylpropyltriacetoxysilane are preferred in terms of stability against acids or bases. preferable.

Examples of vinylsilane compounds represented by (I[) include vinyltriacetoxysilane, vinyltripropionyloxysilane, isopropenyltriacetoxysilane, vinylisopropyldiacetoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylph Enyldiacetoxysilane, vinylmonochlorodiacetoxysilane, vinylmonohydrodienediacetoxysilane, etc. may be mentioned, but vinyltriacetoxysilane is preferred from an economic standpoint.

5 which cannot be obtained by copolymerizing the vinyl silane compounds mentioned above.
The silane content in i-EVOH is 0.0005 to 0.2 mol%, preferably 7 to 0.03 mol% O,OOO'. If the silane content is less than 0.0005 mol%, the adhesion of metal oxides (particularly phosphorus oxide) will not be sufficient, while if it exceeds 0.2 mol%, the degree of crosslinking will increase too much and heat insolubility will occur. I don't like it. Ethylene content is 2
It is 5 to 60 mol%, preferably 25 to 50 mol%.

If the ethylene content is 25 mol%, the amount of moisture absorbed under the environmental humidity conditions during actual use will increase, inhibiting the adhesion of metal oxides, and if the ethylene content exceeds 60 mol%, E
The characteristics of VOH such as gas barrier properties, aroma retention properties, oil resistance, etc. are reduced. The saponification degree of vinyl acetate component is 95% or more,
Preferably it is 96% or more. If the degree of saponification of the vinyl acetate component is less than 95%, not only gas barrier properties, aroma retention properties, oil resistance, etc. will be reduced, but also thermal stability during melt molding will be reduced. Furthermore, there is a drawback that the molded product has an acetic acid odor originating from the acetic acid group, which is transferred to the contents of the package.

Copolymerization of a vinyl silane compound with ethylene and vinyl acetate and saponification of the resulting copolymer can be carried out using known methods.
For example, it can be implemented by a method as shown in Japanese Patent Laid-Open No. 60-144304. In the saponification reaction, the vinyl alkoxysilane units of the copolymer are also partially or highly saponified and converted into vinyl silanol units, their alkali salts, or their intercondensates. However, the general formula (
The vinylsilane compound-containing copolymer represented by II> is kept stable without decomposition of the amide bond of the vinylsilane compound unit in the saponification reaction using an alkaline catalyst. However, during the saponification reaction, the alkoxyl groups, carboxyl groups, hydrogen, and halogens bonded to the silane of the vinylsilane compound represented by the general formula (I[) are also partially or highly saponified and converted to hydroxyl groups or their alkali salts. . Furthermore, when drying the 5i-EVOH obtained after the saponification reaction, some of these hydroxyl groups may be bonded to each other to form siloxane bonds depending on the drying conditions. 5i-EVOH, which has a large number of siloxane bonds, may have poor thermal melting properties. In such cases, the content of the vinyl silane compound should be adjusted, or the unit of the vinyl silane compound should be treated with an alkali. Extremely stable (meth)acrylamide
It is preferable to use S 1-EVOH having a branched alkylsilane unit. Further, the copolymer may be copolymerized with another third component as long as the adhesion of the metal oxide is not impaired.

The third component includes an α-olefin having 3 or more carbon atoms,
Examples include acrylic acid, methacrylic acid, and esters of these acids. Further, in order to improve hot melt moldability, acids, bases, and salts thereof may be added to 5i-EVOH within a range that does not impede the adhesion of the metal oxide. Acids, bases and their salts include acetic acid, boric acid, phosphoric acid, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium acetate, calcium acetate, sodium borate, potassium phosphate, calcium phosphate, calcium hydrogen phosphate, phosphoric acid. Examples include dipotassium hydrogen and potassium dihydrogen phosphate. Furthermore, silicon oxide, aluminum oxide, or the like may be added to Si-EVOH to improve the sliding properties of the molded product. Furthermore, polymers such as nylon, EVOH, and polyolefin may be added to the extent that they do not impede the adhesion of the metal oxide.

The thickness of the metal oxide thin film laminated on the surface of the 5i-EVOH resin is preferably from a monomolecular layer to about 5,000 angstroms, and preferably about 500 to 2,000 angstroms, particularly around 1,000 angstroms.

The most suitable method for laminating a metal oxide thin film on the surface of a 5i-EVOH resin film is vapor deposition.
From the viewpoint of film stability during processing, physical vapor deposition using vacuum and chemical vapor deposition using decomposition of a compound or chemical reaction of a compound are suitable. The gas barrier material obtained in this way can be used as a food packaging material (liquid food packaging material,
It is useful as packaging material for retorts, etc.), pharmaceuticals, and medical equipment.

The present invention will be explained in more detail below using Examples.

E, Examples Example 1 and Comparative Example 1 Silane content 0.01 mol%, ethylene content 32 mol%, vinyl acetate component obtained by saponifying a copolymer of ethylene, vinyl acetate and vinyltrimethoxysilane. A 15 μm thick film of 5i-EVOH with a saponification degree of 99.5 mol% was coated with an electron beam evaporator and
．． The 9 EVOH horse chestnut resin film with a 2000 angstrom oxide film deposited on it was laminated with a 50 μm unstretched polypropylene film via a polyurethane adhesive at 0x10''-' Torr, and then the oxygen permeation rate was measured. The results are shown in Table 1.In addition, in order to clarify the effect of metal oxide vapor deposition, a similar lamination was carried out for a 5i-EVOH resin film (Comparative Example 1) that was not subjected to metal oxide vapor deposition treatment. The sample was prepared as a control.The oxygen permeation rate measuring device used was Oy:toran 10150A manufactured by Modern Controls, and the measurement conditions were 20°C-65%R) (and 20°C-100%R).
Toshina RH. Compared to an EVOH resin film in which no metal oxide is vapor-deposited, the oxygen permeation rate is maintained at a sufficiently low level, especially under high humidity, and the effect of suppressing the relative humidity dependence of the oxygen permeation rate of the EVOH resin film is recognized.

Examples 2 to 6 and Comparative Example 2 Four types of 5i-EVOH resin films with a film thickness of 12 μm and with silane contents varied between 0.0005 and 0.2 mol% were used, and for each sample A 2000 angstrom thick oxide film was then deposited using the method described in Example 1. When measuring the oxygen permeation rate of these, we prepared a sample without bending treatment and a sample with bending treatment after laminating it to a 50 μm thick unstretched polypropylene film via a polyurethane adhesive, and measured the oxygen permeation rate. The results are shown in Table 2. The bending process is Ge1bo Fl
500 rows of ivy by ex-tester. The oxygen permeation rate was measured by the method described in Example 1 at 20°C and 100% RH. EVO) I that does not contain a silane component in its molecular chain
In this case, the oxygen permeation rate of the EVOH resin film after the evaporation treatment shows that the evaporation treatment effect is sufficient without the bending treatment, but the evaporation treatment effect almost disappears after the bending treatment. On the other hand, in the case of the 5i-EVOH resin film, it is clear that as the silane content increases, the effect of the vapor deposition treatment remains even after the bending treatment.

Table 2 with blank space below Example 7 Silane content: 0.02 mol%, ethylene content: 32 mol%, obtained by saponifying a copolymer of ethylene, vinyl acetate and vinyltrimethoxysilane.

5i-EV with saponification degree of vinyl acetate component of 99.5 mol%
On a film with an OH thickness of 15 μm, (SiH4+N
20) The mixed gas is directly photodecomposed by irradiating 40MW/, J of ArF excimer laser light (193nm), and approximately 1
A phosphorus oxide film of 0.000 angstroms was produced. The oxygen permeation rate of this EVOH membrane was measured by the method described in Example 1 after being laminated with an unstretched polypropylene film having a thickness of 50 μm, and the results were compared with that of a 5i-EVOH resin membrane without vapor deposition (Comparative Example 3). It is shown in Table 3. As shown in Example 1, the oxygen barrier properties under high humidity were significantly improved.

Table 3 *: cc#-day・atm
Example 8 Obtained by saponifying a copolymer of ethylene, vinyl acetate and vinyltrimethoxysilane, silane content 0.02 mol%, ethylene content 32 mol%, saponification degree of vinyl acetate component 99.5 mol% The thickness of 5i-EVOH is 12 μm
An aluminum oxide film of about 1200 angstroms was formed on the film by the same operation as in Example 7 except that (trimethylaluminum 10N20) was used as the mixed gas. The oxygen permeation rate of this 5i-EVOH resin film was measured by the method described in Example 1 after being laminated with a 50 μm thick unstretched polypropylene film in comparison with that of a 5i-EVOH resin film without vapor deposition (Comparative Example 4). The results are shown in Table 4. As shown in Example 1, the oxygen barrier properties under high humidity were significantly improved.

F0 Effects of the Invention The gas barrier material of the present invention has almost the same level of gas barrier properties as under low humidity without any decrease in gas barrier properties even under high humidity conditions, and is resistant to mechanical damage such as bending and friction. Gas barrier properties do not deteriorate even when subjected to external force.

Claims (3)

[Claims] (1) Silane content 0.000 obtained by saponifying a copolymer of ethylene, vinyl acetate, and vinyl silane compounds
5 to 0.2 mol%, the degree of saponification of the vinyl acetate component is 95 mol% or more, and the ethylene content is 25 to 60 mol%. Gas barrier property having a thin film of metal oxide on the surface of the ethylene-vinyl alcohol copolymer resin film. material. (2) The gas barrier material according to claim 1, wherein the vinylsilane compound is vinyltrimethoxysilane. (3) The gas barrier material according to any one of claims 1 to 2, wherein the metal oxide thin film is a thin film obtained by a vapor deposition method.