Patent GB-948939-A (GB)
Title: Packaging films and processes therefor
IPC: C08J7/054
Filed: 1960-10-28
Abstract: A coating composition comprises one part by weight of a substituted water soluble cellulose ether having one or more ether linkages per anhydroglucose unit and at least one free hydroxyl group per anhydroglucose unit, from one to eight parts by weight of a water soluble inorganic salt, and water, the water comprising at least 94.5% by weight of the combined weight of ether, salt and water.  The composition may contain an antiblocking agent, examples being given. The water soluble inorganic salt may be an alkali metal salt examples of which are given.  The composition may also contain a finely divided high polymer which softens at a temperature above the maximum storage temperature and which is not substantially soluble in the cellulose ether, examples are given. The composition may be coated on to polyolefin film in the production of wrapping material.ALSO:A coated polyolefin film capable of dispersing moisture condensed thereon in the form of a thin, relatively transparent film, thereby preventing the fogging of the film upon exposure to changes in temperature, comprises a polyolefin film having a coating comprising one part by weight of a substituted water-soluble cellulose ether having one or more ether linkages per anhydroglucose unit and at least one free hydroxyl group per anhydro-glucose unit, and from 1 to 8 parts by weight of a water-soluble inorganic salt.  The coated film may be a transparent wrapping film coated on at least one side thereof. The film may be of a polyolefin having a density of at least 0,935 gm./c.c. and may be of polyethylene, polypropylene, a copolymer of ethylene and propylene, either with each other or with other monomers, examples of which are given.  The watersoluble inorganic salt may be an alkali metal salt, examples being given.  The coating may also contain an antiblock agent or a finely divided high polymer which softens at a temperature above the maximum storage temperature and which is not substantially soluble in the cellulose ether. Examples are given.ALSO:Moist products such as fresh meat, poultry, fruits, vegetables, fish, seafoods, bakery and dairy products, flowers, are packaged in polyolefin film having a coating which disperses moisture condensed thereon as a thin, transparent film and so prevents fogging of the film with changes in temperature, such coating comprising 1 part of a substituted water-soluble cellulose ether having one or more ether linkages per anhydroglucose unit and at least one free hydroxyl group per anhydroglucose unit to 1-8 parts of a water-soluble inorganic salt.  The coated film may be transparent and may be coated on one or both sides.  The film, preferably of density at least 0.935 g./ml., may be of polyethylene, polypropylene, or a co-polymer of ethylene and proprylene with one another or with another monome.  The coating may also contain an anti-blocking agent e.g. wax, starch, fine silica, clay, a water-insoluble salt, or a finely-divided high polymer softening at a temperature above the maximum storage temperature and insoluble in the cellulose ether, e.g. polyvinyl chloride and its copolymers, polystyrene, polymethylmethacrylate.