Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Patent
1996-05-17
1998-06-02
Thibodeau, Paul J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
428 349, 428 352, 428 374, 428515, 428516, 42817311, 26417311, 26417314, 26417315, 26417316, 2642884, B32B 2732, B65B 5302
Patent
active
057596751
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a multi-layer stretchable, shrinkable polyethylene film and a process for the preparation thereof. More particularly, the present invention relates to a multi-layer stretchable, shrinkable polyethylene film which is particularly suitable as a stretch or shrink packaging film used for prepackaging of retailed articles, mainly foods, and which is excellent in applicability to automatic packaging machines and restoration from deformation.
BACKGROUND ART
In recent years, a demand for stretchable films for packaging foods such as meats, sea foods, vegetables, fruits and daily dishes is further increasing with the increase of the number and expansion of the scale of supermarkets and convenience stores. Heretofore, as the above-mentioned stretchable films, a film prepared from a plasticized polyvinyl chloride as a raw material has been most widely used, since the film has excellent properties such as transparency and self-tackiness. However, the film has the disadvantages that since a large amount of a plasticizer is used, steam permeates through the film in an increased amount to easily cause a weight loss or a deterioration of a packaged object, or the plasticizer is easy to migrate to the packaged object to contaminate it, and that harmful hydrogen chloride gas is generated during formation of the film, melt-cutting of the film in packaging work, destruction of the film by fire, and the like, thus a problem arises in safety, sanitary and environmental pollution.
Therefore, films which can be substituted for the plasticized polyvinyl chloride film have been actively developed using an ethylene resin such as polyethylene or ethylene-vinyl acetate copolymer, a polybutadiene resin, and the like. Although the polyethylene or polybutadiene resin films have no problem in safety, sanitary and environmental pollution, they are not fully satisfactory as a stretchable film.
For instance, a non-stretched low density polyethylene does not give beautiful packaging finish, since the film causes a necking phenomenon that only a part thereof elongates to result in marked unevenness in thickness, when the film is stretched for the purpose of stretch packaging, and since the restoration from deformation is small. Further, the film strength is poor and the transparency is unsatisfactory. So, in order to solve these problems, it has been attempted to provide the film with a high orientation by biaxial stretching. However, for example, a low density polyethylene has technical problems such that the film is broken during the processing. Thus, the obtained film has no effective molecular orientation and, therefore, is poor in strength. Also, the heat shrinkability is revealed only at high temperatures close to its melting point.
Also, there are proposed films composed mainly of crystalline 1,2-polybutadiene or ethylene-vinyl acetate copolymer to which an antifogging agent and a tackifier are added. However, these films have no heat shrinkability, and have the disadvantage that if packaging is attempted with these films, the breaking is easy to occur at the corner of a tray due to poor film strength.
Further, recently, with diversification of objects to be packaged and spread of automatic packaging machine, there have been demanded packaging materials having an applicability to automatic packaging machines, such as packaging materials capable of heat sealing and having, in addition thereto, a heat shrinkability.
In order to overcome the above-mentioned defects of the stretchable films and to meet these demands, the present inventors previously proposed a multi-layer stretchable, shrinkable polyethylene film having a heat shrinkability and a stretchability, and being capable of heat sealing by a plate heater, and giving good finished shrink packages such that the sealing joints did not peel off even if water adhered to the joints (Japanese Patent Publication Kokai No. 3-215034).
However, in the above-mentioned multi-layer stretchable, shrinkable polyethylene film, too, the stretchabi
REFERENCES:
patent: 4801652 (1989-01-01), Mizutani et al.
patent: 4985197 (1991-01-01), Isozaki et al.
patent: 5407732 (1995-04-01), Dolurno
patent: 5635286 (1997-06-01), Morita et al.
Hamada Kazuhiro
Isozaki Hideo
Matsumoto Tooru
Saeki Osamu
Kohjin Co., Ltd.
Tarazano D. Lawrence
Thibodeau Paul J.
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