Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2002-06-21
2004-06-08
Buttner, David J. (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S413000, C428S500000, C428S523000
Reexamination Certificate
active
06746772
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oxygen-absorbing multi-layer film used in packaging materials for food, pharmaceutical and the like that are intended for the preservation of contents in packages by oxygen absorption.
2. Description of the Related Arts
In recent years, there have been prevalently used plastic films and plastic containers in packaging materials intended for the preservation of contents in packages by reason of their light weight, economical efficiency and the like. Performances required of the plastic films that are used for packaging food, pharmaceutical, cosmetics and the like include gas barrier properties against a variety of gases, transparency, resistance to retorting treatment, impact resistance, flexibility, heat sealability. Of these, high gas barrier properties against oxygen and steam are required in particular under the conditions of high humidity, after retorting treatment for the purpose of preserving the performances and properties of the contents in packaging materials.
On the other hand, for the purpose of preserving food, pharmaceutical and the like, there are used an deoxidant in which an iron based oxygen-absorbing agent is packaged in an gas permeable packaging material and an deoxidant of label type, packing type or card type in which an oxygen-absorbing resin composition composed of a thermoplastic resin and an oxygen-absorbing agent compounded therewith is packaged in an gas permeable packaging material. Further as one of deoxidizing packaging techniques, deoxidizing containers are under development, including a packaging container comprising multi-layer materials which are equipped with an oxygen-absorbing layer having a resin composition composed of a thermoplastic resin and an oxygen-absorbing agent compounded therewith, and which are imparted with deoxidizing function.
As an oxygen-absorbing resin composition composed of a resin and an iron based oxygen-absorbing agent compounded therewith, there is described an iron based oxygen-absorbing agent dispersed in and mixed with a thermoplastic resin in Japanese Patent Application Laid-Open Nos. 158257/1985 (Showa 60), 281964/1988 (Showa 63), 90847/1992 (Heisei 4), 268140/1995 (Heisei 7), etc. There is described an oxygen-absorbing multi-layer body such as a multi-layer sheet, multi-layer film and the like each having an iron based oxygen-absorbing resin layer in Japanese Patent Application Laid-Open Nos. 72941/1996 (Heisei 8), 309323/1995 (Heisei 7) and 40024/1997 (Heisei 9).
In general, an oxygen-absorbing multi-layer body is composed by laminating each of film materials which constitute a protective outer layer, a gas barrier layer, an oxygen-absorbing layer and a sealant layer, respectively, wherein the adhesion between the gas barrier layer and oxygen-absorbing layer is made by extrusion lamination or dry lamination. However the oxygen-absorbing multi-layer body comprising a gas barrier layer, an adhesive layer, an oxygen-absorbing layer and a sealant layer inevitably causes an increase in total thickness owing to the presence of the oxygen absorbing layer as compared with a conventional gas barrier film as mentioned above, thus bringing about deterioration in flexibility of the resultant laminate.
As materials which have gas barrier properties and constitute a gas barrier layer, there are known polyvinylidene chloride (PVDC) films, ethylene-vinyl alcohol copolymer (EVOH resin) films, polyvinyl alcohol (PVA) films, meta-xylylene adipamide films, inorganic vapor deposited films that are deposited with alumina (Al
2
O
3
), silica (SiOx) aluminum foils. The above-exemplified materials are properly selectively employed according to the characteristics separately by the type of content and the purpose of use. In the case of laminating an oxygen-absorbing layer with a material having gas barrier properties, there are used a dry lamination method which comprises coating a material having gas barrier properties with an adhesive, and allowing an oxygen-absorbing layer to adhere thereto, an extrusion lamination method which comprises coating a material having gas barrier properties with an anchor coating agent at need and press bonding a molten resin composition layer functioning as an oxygen-absorbing layer thereonto to produce a filmy laminate. As the adhesive and anchor coating agent, there is prevalently used a two-component polyurethane adhesive composed of a principal ingredient bearing an active hydrogen group such as hydroxyl group and a curing agent bearing an isocyanate group from the standpoint of sufficient adhesivity {for instance, refer to Japanese Patent Application Laid-Open No. 316442/1997 (Heisei 9)}.
That is to say, the conventional oxygen-absorbing multi-layer body has suffered from a disadvantage from the aspects of economical efficiency, workability in production steps because of the necessity of separately installing a layer which assumes a role of allowing an adhesive layer or anchor coat layer to adhere between the gas barrier layer and the oxygen-absorbing layer.
SUMMARY OF THE INVENTION
A general object of the present invention is to eliminate the problems as mentioned hereinbefore, and thus to provide an oxygen-absorbing multi-layer film which has oxygen-absorbing function, which is excellent in economical efficiency, film rigidity and contents preservability and which is used in packaging materials for food, pharmaceutical and the like.
Other objects thereof will become obvious from the text of this specification hereinafter disclosed.
As a result of intensive research and investigation made by the present inventors it has been found that there is obtainable a laminated film which is excellent in a variety of performances such as gas barrier properties, interlaminar adhesivity, resistance to retorting treatment, impact resistance and flexibility as well as economical efficiency by using a cured product formed with a specific component as an epoxy base resin adhesive between an outer layer and an oxygen-absorbing layer. The present invention has been accomplished by the foregoing findings and information.
Specifically, the present invention relates to an oxygen-absorbing multi-layer film which comprises an outer layer comprising a thermoplastic resin; an adhesive layer comprising an epoxy resin; an oxygen-absorbing layer comprising a thermoplastic resin and an iron based oxygen-absorbing agent incorporated therein; and a heat sealing layer comprising an oxygen-permeable thermoplastic resin, wherein said adhesive layer comprises a gas barrier epoxy resin composition containing at least 30% by weight of a xylylene diamine unit.
In particular, the present invention pertains to the above-mentioned oxygen-absorbing multi-layer film wherein said gas barrier epoxy resin composition comprises an epoxy resin containing xylylene diamine units.
In particular, the present invention is concerned with the above-mentioned oxygen-absorbing multi-layer film wherein said gas barrier epoxy resin composition is formed by curing an epoxy resin with an epoxy resin curing agent, said epoxy resin curing agent containing a xylylene diamine unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, detailed description will be given of the oxygen-absorbing multi-layer film according to the present invention.
The outer layer usable in the present invention comprises a thermoplastic resin as far as it can be coated with an adhesive layer, and is exemplified by films of polyolefin base such as polyethylene and polypropylene, films of polyester base such as polyethylene terephthalate, films of polyamide base such as nylon 6 and nylon 6,6, poly(meth)acrylic base films, polystyrenic base films, ethylene-vinyl aicohol copolymer (EVOH) base films and polyvinyl alcohol base films. Of these are preferable polyolefin base films, polyester base films and polyamide base films.
These films are preferably oriented uniaxially or biaxially and the practical thickness thereof is in the range of about 10 to 300 micron, preferably about 10
Kashiba Takashi
Kihara Shuta
Kutsuna Takaaki
Antonelli Terry Stout & Kraus LLP
Buttner David J.
Keehan Christopher
Mitsubishi Gas Chemical Company Inc.
LandOfFree
Oxygen-absorbing multi-layer film does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxygen-absorbing multi-layer film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen-absorbing multi-layer film will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3312960