JPS6220278Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention not only has a low gas permeability for oxygen, nitrogen, carbon dioxide, hydrogen, helium, and argon, but also has a low water vapor permeability, and its excellent gas barrier ability remains almost constant even after high-temperature steam sterilization at 100 to 150℃. It is an object of the present invention to provide a gas barrier film that has excellent values without changing. Of course, there was no transparent film that had excellent gas barrier properties and could withstand steam sterilization.
For example, modified polyvinyl alcohol resin “EVAL” is a transparent polymer with excellent oxygen barrier properties.
(manufactured by Kuraray Co., Ltd., however, the name in “ ” indicates a trademark. The same applies hereinafter) is commercially available, but although this polymer has excellent oxygen barrier properties, it has no water vapor barrier properties at all. Moreover, if the resin is steam sterilized at a high temperature of 100°C or higher, the resin will flow out and the gas barrier ability will be lost. For this purpose, the "Eval" (manufactured by Kuraray Co., Ltd., but "
(Names in "indicate trademarks. The same applies hereinafter.) Water vapor barrier properties at room temperature can be imparted by laminating polyolefins with excellent water vapor barrier properties, such as polyethylene or polypropylene layers, on both sides of the layer. , Prevents resin leakage during high-temperature steam sterilization (manufactured by Kuraray Co., Ltd.; however, names in parentheses indicate trademarks; the same applies hereinafter) and deterioration of oxygen barrier properties after treatment. Other resins with excellent oxygen barrier properties include polyacrylonitrile,
For example, "Valex" (manufactured by Mitsui Toatsu Chemical Co., Ltd.) is similar to polyvinyl alcohol resin, and not only has water vapor barrier properties, but also has oxygen barrier properties after sterilization, as the resin whitens and cracks when sterilized with high temperature steam. becomes very bad. In addition, polyvinylidene chloride resins such as "K-Flex" (manufactured by Kureha Chemical Industry Co., Ltd.) and "Saranex"
(manufactured by Asahi Kasei Kogyo Co., Ltd.) is the same, especially at 137°C.
If the above high-speed retort/steam sterilization is performed, the oxygen barrier properties will be greatly deteriorated. Therefore, the inventors of the present invention found that the permeability of gases such as oxygen, nitrogen, carbon dioxide, hydrogen, helium, and argon is extremely low, and the permeability of water vapor is also low.
As a result of extensive research into a transparent thermoplastic polymer film that can withstand steam sterilization at temperatures above 100°C, we have arrived at the present invention. In other words, the gist of the present invention is that layer A made of aromatic polyamide or modified polyvinyl alcohol and layer B made of modified polyolefin are laminated together in 130 or more layers, and the thickness of each layer of layer A is 1 μm or less. This relates to a certain gas barrier film. The key point of the present invention is that retort resistance is improved by creating a multilayer laminate with 130 or more thin layers of 1 μm or less. Aromatic polyamide is a polyamide compound with an aromatic ring. Typical examples include polymethaxylylene adipamide (mxD6), a copolymer of metaxylylene terephthalamide and epsilocaprolactam or isophthalic acid (mxDT). /6, mxDT/I), polyhexamethylene (terephthalamide/isophthalamide) copolymer (6I/6T), epsilocaprolactam and p
- Copolymer with aminomethylbenzoic acid (AMBA/6), polytetramethylene isophthalamide (4I) and its copolymer, polyethylene isophthalamide copolymer (2I series), m-aminomethylbenzoic acid Acid polymer, copolymer of p-aminobenzoic acid and hexamethylene adipamide (66/
AMBA), p-aminobenzhydrazide, and copolymers of each of the above, but in particular mxD6, 6I/6T (70/30 to 50/50 molar ratio), 4I/6I/6T, Aromatic polyamides consisting of 6I/6T/4 and 2I/6I are preferred. The modified polyvinyl alcohol is a polymer containing 50 mol% or more of a polyvinyl alcohol component, and other components include copolymerized olefins such as ethylene. Typical examples include "Eval" (manufactured by Kuraray Co., Ltd.), "Syobar" (manufactured by Showa Denko Co., Ltd.), and "GL Resin" (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.). Both modified polyvinyl alcohol and aromatic polyamide have an oxygen permeability of 20℃,
10 (cc/m ² , 24hrs/0.1 in bone dry condition (ORH%)
mm) or less, preferably 1 (cc/m ² , 24hrs/0.1
mm) or less. Modified polyolefin is a product obtained by copolymerizing or graft copolymerizing polyolefin with compounds such as methyl acrylate, acrylic acid, methacrylic acid, metal salts of methacrylic acid, glycidyl methacrylate, maleic acid, and vinyl acetate. “Zetafin”
(manufactured by Dow Chemical Corp.), "Dexon" (manufactured by Etsuso Chemical Co., Ltd.), "Zaikusen" (manufactured by Steel Chemical Corp.), "
There are commercially available products such as ``Bond First'' (manufactured by Sumitomo Chemical Co., Ltd.), ``Surlyn'' (manufactured by Du Pont), and ``Admar'' (manufactured by Mitsui Petrochemical Industries, Ltd.). is 3 (g/m ² , 24 hrs/0.1 mm) or less, preferably 1.5 (g/m ² , 24 hrs/0.1 mm) or less, and the interlayer with aromatic polyamide or modified polyvinyl alcohol, which has a low oxygen permeability, is It is necessary to select a material with excellent adhesive strength. In the case of the film of the present invention, a particularly preferred modified polyolefin is polyethylene copolymerized with maleic anhydride (for example, "Admer"). layer (water vapor barrier layer)
130 or more layers, preferably 250 or more layers, more preferably 1000 or more layers, and the A layer 1
The thickness per layer is less than 1 micron, preferably 0.01
Must be in the range ~0.1 micron. If the number of layers or thickness is outside the above range, the oxygen barrier properties after high-temperature steam sterilization will be greatly deteriorated, which is not preferable. Further, the thickness of each layer of the B layer varies depending on the application, and is often approximately the same thickness as the A layer or less. Of course, it goes without saying that it is preferable that each thin layer has a pinhole in the middle and is not cut. Although the total thickness of the film of the present invention can be selected arbitrarily, it is easy to use a thickness in the range of 1 to 50 microns when used as a gas barrier layer, and 100 to 1000 microns when used as a molding sheet. Of course, each layer of the film of the present invention may contain other polymers and optional additives, such as stabilizers, ultraviolet absorbers, antioxidants, plasticizers, thickeners, thinners, pigments, nucleating agents, lubricants, and antistatic agents. It may also contain agents. The film of the present invention can be manufactured all at once in one simple, continuous process as described below.
It is not necessarily limited to this. Oxygen barrier resin A and water vapor barrier resin B are separately melted, the melts are combined, and the melts are laminated in a multilayer flow in a mixer such as a square mixer. It is then cooled and solidified. If necessary, stretching or rolling or heat treatment may be performed in the longitudinal direction or width direction, and in the case of the film of the present invention, it is particularly preferable to include a rolling step. It will be appreciated that other polymers may also be laminated to at least one side of the invented film, such as polyethylene terephthalate, nylon 6, and polypropylene. The method for measuring water vapor transmission rate used in this invention is
It was measured by the cup method according to JIS Z-0208 method, and the oxygen transmission rate was measured using “MOCON” OX-
The values are measured using TRAN-100 model (manufactured by MODERN CONTROL) at 20°C and in an absolutely dry state. Comparative examples and examples will be shown below to make the present invention easier to understand, but the invention is not necessarily limited thereto. Examples 1 and 2, Comparative Examples 1 to 3 As the oxygen barrier resin A, "EVAL" E (manufactured by Kuraray Co., Ltd.), which is a modified polyvinyl alcohol resin (ethylene content: about 33 mol%) copolymerized with ethylene, As water vapor barrier resin B, "ADMER" LF-300 (manufactured by Mitsui Petrochemical Industries, Ltd.), which is a modified polyethylene copolymerized with maleic anhydride (maleic anhydride content: approximately 0.007 mol%), was used as shown in Table 1. 3 layers, 65 layers, 121 layers, 151 layers and
A 257-layer composite film was formed using a square mixer as shown in Japanese Patent Publication No. 39-437, and its water vapor barrier properties [H ₂ D] and oxygen barrier properties [O ₂ ] were measured, and the results are shown in Table 1. It was shown to.

[Table] It can be seen that in the case of a multi-layered film like the film of the present invention, there is almost no decrease in oxygen barrier properties and water vapor barrier properties after boiling water treatment. Examples 2 to 4 The number of stages of the square mixer used in Example 2 was 8.
Similar comparisons were made by increasing the number of layers from 257 to 512 and 1025 by increasing the number of layers to 9 and 10, and the results are shown in Table 2. When the number of layers is increased in this manner, almost no deterioration in oxygen barrier properties is observed after boiling treatment. Example 5 The multilayer laminated sample used in Example 2 was heated at 70°C for 5 minutes.
After rolling in the longitudinal direction and heat treating at 150°C for 30 seconds, measurements were performed in the same manner as in Example 2, and the results are shown in Table 3.
It was shown to. By rolling the multilayer laminated sample in this manner, it exhibits even better properties.

【table】

[Table] Example 6 1025-layer multilayer laminated film used in Comparative Example 4 (20
A 20 micron low-density polyethylene film was laminated on one side of the film, and a 12 micron biaxially stretched polyethylene terephthalate film was laminated on the other side via a 1 micron adhesive layer to obtain a 53 micron film. Bags are made using a heat sealer using the polyethylene side of the film as a sealant,
After steam sterilization at 137℃ for 5 minutes, the oxygen permeability was measured to be 0.9 (cc/ ^m2.day /sheet)
It had very good oxygen barrier performance. Example 7 Polymethaxylylene adipamide (mxD6; relative viscosity in 98% sulfuric acid 2.20) as an oxygen barrier layer,
“ADMER” LF-300, which is a modified polyethylene copolymerized with maleic anhydride (maleic anhydride content approximately 0.007 mol%), is used as a water vapor barrier layer.
(manufactured by Mitsui Petrochemical Industries, Ltd.), 1024 layers of the same thickness were laminated using a 10-stage square mixer, and extruded from a T-die die to obtain a cast film of 150 microns. The cast film
After stretching 3 times in the width direction at 100°C, rolling 3 times in the longitudinal direction at 80°C, and heat-treating in an oven for 20 seconds at 160°C.
A micron multilayer laminated film was obtained. The properties of the film are listed below, and it can be seen that the film not only has excellent gas barrier properties, but is also mechanically very strong.

【table】 [Brief explanation of the drawing]

Figure 1 shows the surface layer A of a typical film of this invention.
It is a sectional view showing a laminated state up to the layers, where A is a layer made of aromatic polyamide or modified polyvinyl alcohol having oxygen barrier properties, and B is a layer made of modified polyolefin having water vapor barrier properties.

Claims (1)

[Scope of utility model registration request] A gas barrier film comprising 130 or more layers of layer A made of aromatic polyamide or modified polyvinyl alcohol and layer B made of modified polyolefin, each of which has a thickness of 1 μm or less.