Firearms
Patent
1996-09-10
1998-05-12
Bell, Janyce
Firearms
427156, 427374, 4273855, 4273481, B65B 3300
Patent
active
057501890
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for protecting surfaces from non-desired contamination and for facilitating removal of such contamination from the surfaces.
In EP B1 0 365 584 there is described a contamination removal process based on the use of a solution containing a polysaccharide and a solvent therefor for creating a protective coating on a surface. After being subjected to contamination such protective surface can be easily freed from the contamination by treating the coated surface with a liquid which is capable of redissolving the protective coating or providing for swelling thereof. The invention according to said patent specification constitutes an excellent solution to the contamination problem as reflected by contamination resulting from so called graffiti, traffic pollution etc.
The present invention constitutes a significant improvement of the techniques disclosed in EP B1 0 365 584, and the purpose of the present invention is to provide for a polysaccharide film which has low solubility in water of room temperature.
A number of polysaccharides, for example carageenan and agar, which are dissolved in water at an increased temperature form at certain minimum concentrations gels when such solution is cooled to a lower temperature. Continued evaporation of water results in the formation of a film which frequently is resistent to dissolution and can be dissolved or made to swell only at an increased temperature.
The coating of surfaces with polysaccharide solutions at an increased temperature is difficult, and to apply a polysaccharide gel by spraying or the like results in inferior adhesion to the substrate since the solvent is inextricably bound in the gel structure.
The problem to be solved by the instant invention can be said to reside in finding new techniques, whereby it is possible to make use of the advantages associated with gel formation as an intermediate stage while at the same time providing for a concentration of polysaccharides in the solution resulting in a film of sufficient thickness. If a polysaccharide of the gelling type is used alone the concentration thereof in solution has to be very low in order to obtain a solution thereof that can be applied without difficulty. If the concentration is increased to a level which will result in sufficient film thickness then gelling will occur and the application by spraying or the like will constitute a severe problem. The invention solves this problem in a satisfactory way and thereby constitutes a significant advance in the art.
The present invention aims at solving the problem of obtaining a resistant coating or film constituted by polysaccharides while making use of the advantage of gel formation as an intermediary step in the process of obtaining the film.
To this end the invention provides for a process for protecting a surface from non-desired contamination and for facilitating removal of said contamination from the surface, and said process involves the following steps:
a) preparing a solution of polysaccharides containing at least two components, wherein one component is constituted by a first polysaccharide which, when precipitated from a solution by evaporation of the solvent thereof, directly forms a film, and wherein the second component is constituted by a second polysaccharide which, when precipitated from a solution by evaporation of the solvent thereof, forms a film via at least partial gel formation, or by interaction with said first polysaccharide, when precipitated from a solution by evaporation of the solvent thereof, forms a film via at least partial gel formation, said films being redissolvable or swellable;
b) applying the solution from step a) onto said surface before subjected to contamination;
c) allowing the applied solution to dry so as to form a solid film on said surface via at least partial gel formation;
d) treating the film-coated surface with a liquid capable of redissolving film or providing swelling thereof; and
e) removing the non-desired contamination by complete or partial removal of the
REFERENCES:
patent: 5017237 (1991-05-01), Svensson
patent: 5093485 (1992-03-01), Svensson
patent: 5308647 (1994-05-01), Lappi
patent: 5395646 (1995-03-01), Basseres et al.
patent: 5418006 (1995-05-01), Roth et al.
Bell Janyce
Polysaccharide Industries AB PSI
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