Stock material or miscellaneous articles – Composite – Of polyamide
Reexamination Certificate
2001-04-26
2003-02-25
Hampton-Hightower, P. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamide
C428S474400, C428S411100, C428S474900, C428S475200, C428S475500, C428S477700, C428S480000
Reexamination Certificate
active
06524719
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a laminate film which is outstanding in its oxygen and water vapour barrier properties, and to a vapour-deposited film employing same.
TECHNICAL BACKGROUND
For the purposes of storing foods and pharmaceutical products over a long period of time, it is necessary to carry out packaging which is outstanding in its gas barrier properties, that is to say which has the effect of preventing penetration from outside of the oxygen and water vapour which accelerate deterioration and putrefaction. In recent years, there has been an increasing demand that the film packaging with outstanding gas barrier properties used for this purpose be transparent in order to enable, in particular, the state of the contents to be ascertained.
Now, as an example of non-transparent packaging which possesses high-level gas barrier properties, there is known film packaging where aluminium foil has been laminated but, when compared to polymer film, aluminium foil has poor flexing characteristics and pinholes are produced by, for example, folding-over during processing and the like, so the gas barrier properties are easily impaired, and hence there is desired a replacement film having high-level gas barrier properties matching aluminium foil.
As examples of transparent gas barrier films, there are known those where polyvinylidene chloride or ethylene/vinyl alcohol copolymer is laminated. Moreover, it is already well-known that where metal compounds are formed on a polymer film the gas barrier properties and transparency are good.
However, conventional transparent gas barrier films have problems of the following kind. Polyvinylidene chloride resin or ethylene/vinyl alcohol copolymer resin laminate films are inadequate in their oxygen and water vapour gas barrier properties and, in particular, there is a marked lowering thereof in high temperature sterilization treatments. Furthermore, when incinerated, polyvinylidene chloride produces chlorine gas and there are concerns about its effects on the terrestrial environment.
On the other hand, film where a coating of silicon oxide or aluminium oxide has been formed by vapour-deposition has excellent barrier properties but, in recent years, as eating habits have become more sophisticated, and along with the appearance of various different kinds of food products and cakes/confectionary on the market, the enhancement of properties such as the barrier properties and the prolonged maintenance of product quality have come to be regarded as even more important. In particular, in the packaging of snack confectionary and foods, gas barrier properties which exceed those achieved hitherto have begun to be demanded to prevent oxidation or dampening of the contents, and in order to ensure fresh quality over a long period.
In order to meet such requirements, for example in JP-A-10-29264 there is described the provision of an inorganic vapour-deposited layer on a polyamide film; in JP-A-7-223305 there is described a polyester/aromatic polyamide laminate film; and in JP-A-9-174777 there is described the provision an inorganic vapour-deposited layer on the polyester side of a polyamide/modified-polyester laminate film. While the gas barrier properties are certainly improved thereby, they do not achieve the high levels recently demanded.
Consequently, the objective of the present invention lies in overcoming the problems of the prior art and, with the aim of markedly enhancing the gas barrier properties in respect of oxygen and water vapour of vapour-deposition film, offering a film for vapour deposition which is made to manifest outstanding gas barrier properties; together with a vapour-deposited film employing same.
DISCLOSURE OF THE INVENTION
The present invention relates to a laminate film where a polyester film or an aliphatic polyamide film is employed as a substrate layer (the A layer), and where a polyamide layer (the C layer) in which the chief component is an aromatic polyamide of glass transition temperature at least 60° C. is employed as a layer to undergo vapour deposition, and the centre-line average roughness (Ra) of the face which is to undergo vapour deposition is in the range 0.005 to 0.03 &mgr;m. Furthermore, the present invention relates to a laminate film where a polyester film or an aliphatic polyamide film is employed as a substrate layer (the A layer), and where a polyamide layer (the C layer) in which the chief component is an aromatic polyamide of glass transition temperature at least 60° C. is employed as a layer to undergo vapour deposition, and between the A layer and the C layer there is interposed a layer (the B layer) comprising polymer of SP value 10 to 15. Moreover, the present invention also relates to a packaging film where an inorganic thin film has been vapour-deposited on the vapour-deposition face of said laminate film.
Optimum Form for Practising the Invention
Polyester film in the present invention refers to a polymer film comprising a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component are isophthalic acid, terephthalic acid, phenyl-4,4′-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, diphenoxyethane-4, 4′-dicarboxylic acid, diphenylsulphone-4,4′-dicarboxylic acid, diphenylether-4,4′-dicarboxylic acid, malonic acid, 1,1-dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, decamethylenedicarboxylic acid and the like but, amongst these dicarboxylic acid components, film comprising an acid component in which the chief component is terephthalic acid and/or 2,6-naphthalenedicarboxylic acid, is preferred. If the chief component is other than terephthalic acid or 2,6-naphthalenedicarboxylic acid, the adhesive strength of the vapour-deposited film tends to be inferior and it may be difficult to obtain outstanding gas barrier properties.
On the other hand, examples of the glycol component are glycol components such as ethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-propanediol and other such aliphatic glycols, cyclohexanedimethanol and other such alicyclic glycols, and bisphenol A, bisphenol S and other such aromatic glycols, and also polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer materials such as polyethylene glycol/propylene glycol copolymer but, of these, a glycol component in which ethylene glycol is the chief component is preferred. With other than ethylene glycol as the chief component, the adhesive strength of the vapour-deposited film tends to be inferior and it may be difficult to obtain outstanding gas barrier properties. Now, there may be jointly used two or more such dicarboxylic acid components and/or glycol components.
Other polyesters can be incorporated into the polyester film within a range such that the effects of the invention are not impaired. Examples of such other polyesters are polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polyhexamethylene terephthalate (PHT), polyethylene naphthalate (PEN), polycyclohexane-dimethylene terephthalate (PCT), polyhydroxybenzoate (PHB) and copolymer resins thereof.
Furthermore, aliphatic polyamide film in the present invention refers to a polyamide film obtained by the ring opening polymerization of a lactam, the polycondensation of an aminocarboxylic acid or the polycondensation of a diamine and dicarboxylic acid. Specific examples are polyamide 6, polyamide 12, polyamide 11, polyamide 6-6, polyamide 6-10, polyamide 6-12 and copolymers or mixtures thereof.
The film of the present invention needs to have a substrate layer selected from polyester films and aliphatic polyamide films and, in terms of the vapour-deposition processability, a polyester film is preferred.
The aromatic polyamide in the present invention is a polyamide in which at least 85 mol % of the amide bonds are obtained from a aromatic diamine and/or an aromatic dicarboxylic acid component
Hashimoto Kokichi
Kimura Masahiro
Yamane Nobuhisa
Hampton-Hightower P.
Kubovcik & Kubovcik
Toray Industries Inc.
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