US2389761A - Container closure - Google Patents

Description

Nov. 27, 1945. A. BURGENI CONTAINER CLOSURE Filed May 22, 1942 COAGULATED COAGULATED FIGJ COAGULATED FOAM COAGULATED FIG.5

COAGULATED COAGULATED MEI FIG.6

FIC5.3

INVENTOR.

Patented Nov. 27, 1945 UNITED STATES PATENT OFFICE CONTAINER cLosUiu:

Alfred Burgeni, East Orange, N. J. Application May 22, 1942, Serial No. 444,082

7 Claims.

Thi invention relates to container closures and more particularly to closures having a novel sealing element of a coagulated foam.

Emcient sealing of bottles, jars and similar contalners requires that an inert and chemically stable surface be tightly but resiliently held over the opening of the container being sealed. Many types of sealing members and sealing assemblies have been used for the purpose, but they have not been altogether satisfactory since they have been insufliciently resilient, or have flavored .container contents adversely, or have lacked inertness, or have been non-uniform and inconsistently available.

In accordance with this invention, these disadvantages are overcome by a sealing member of resilient water-insoluble coagulated foam formed of a hydrophilic polymeric substance. The foam is controllably resilient, stable and inert. It may serve as the surface in contact with the contained material and also provide the resilient support desirable to insure sealing. A closure in accordance with this invention, therefore, comprises a closure body adapted to hold a sealing member in sealing relation to a container opening, with fastening means capable of engaging the container, and a sealing member of the coagulated foam. In some cases, the coagulated foam sealing member may serve as a, container stopper or closure without added support.

The coagulated foam is a resiliently rigid solid structure containing myriads of hollow spaces or cells in the nature of very small bubbles, some readily visible but many visible only under magnification. The poresor cells are for the most part enclosed by thin walls forming a continuous structure preventing flow from cell to cell so that penetration by gases and liquids is very slow. Foams differ from sponges in this respect, since the voids in sponges are communicating.

Some examples of closures in accordance with this invention are shown in the sectional views in the accompanying drawing in which:

Figure 1 is a crimp type closure having a sealing disc of coagulated foam;

Figure 2 is a screw cap having a sealing disc of coagulated foam and a thin impervious facing on the foam disc;

Figure 3 is a screw cap having a sealing disc of coagulated foam formed by casting liquid foam into a recessed closure body prior to coagulation in situ;

Figure 4 is a screw cap with an annular sealing ring of coagulated foam and a thin disc of impervious facing for contact with the contents of a container;

Figure 5 is a plug closure with a supporting member and a stopper type coagulated foam seating member (alternatively the entire structure may be of the coagulated foam') Figure 6 is a crimp type closure with an inside conical annular sealing member of coagulated It will be appreciated many other shapes of closure sealing members may be suitably prepared of the coagulated foam.

The coagulated foam member in accordance with this invention is obtained by preparing a foam of a liquid comprising a highly P lymeric cellulose glycollic acid, all of the water-soluble type, dissolved in water or similar cellulose ethers of the cold-alkali-soluble type dissolved in aqueousalkali; aqueous solubilized casein, soya bean protein or similar vegetable protein; aqueous polyvinyl alcohol; and the like. Coagulation is accomplished by'heating-the liquid foam or by treating it with a salt, with an acid substance, for example, gaseous sulphur dioxide or an aqueous acid, or other coagulant. Coagulation preferably involves a chemical change which insolubilizes the polymeric substance. For example, cellulose xanthogenate is decomposed to cellulose, casein may be insolubilized and coagulated with tannic acid or formaldehyde, cellulose glycollic acid may be insolubilized by formation of an insoluble salt on treatment with a soluble barium or strontium salt.

The coagulated foam is preferably insoluble in water but it is advantageous for it to be hydrophilic so that water causes slight swelling, insuring an efficient sealing action in the presence of aqueous container contents.

The known coagulated foam developed by Herzog and Hoffman by heat or acid coagulation of viscose foam has been found to be particularly suitable for the present purpose. It is made by preparing a viscose, i. e., a solution of an alkali cellulose xanthogenate in water or dilute alkali, then preparing a liquid foam of the viscose, and coagulating the viscose foam to a regenerated cellulose foam. A regenerated cellulose foam may, for example, be prepared as follows:

An alkali cellulose of 14-15% sodium hydroxide is prepared in the usual manner and aged for av period of about six hours. The aging period may vary but preferably is less than 10 hours. The aged alkali cellulose is then reacted with carbon disulphide in'a ratio of 10 kg. of the latter for each kg. of alkali cellulose for approximately 6 hours'at 23 C. The resulting cellulose xanthogenate is then dissolved in five times its weight of water. A quantity of water between 4 and 7 rods, other molded shapes, or into a reces therefor in a closure body. The cast viscose foam is then heated, preferably at about fill-100 C., and preferably in an atmosphere substantially saturated with water vapor. The heat causes spontaneous coagulation of the viscose foam, usually in less than 48 hours, to form a solid coagulated with chemical change of the xanthogenate to regenerated cellulose. The coagulated form is washed for a prolonged period in running water until it is substantially free of water-soluble substance, and then dried. For some purposes washing may be superficial or merely sufficient to remove most of the water-soluble materials.

The dried foam may be cut to the desired shape for subsequent use as a sealing member if further shaping i required. However, a container closure may be prepared, in accordance with this invention by casting a liquid foam in or about a suitable container body adapted to receive the foam, into substantially the ultimate shape and position of tne solid foam. The liquid foam is then coagulated in situ, washed if desired, and dried.

The rigidity and resilience of a coagulated foam may be controlled at will. Rigidity (and density) of the coagulated foam is regulated most easily by regulation of the concentration of the polymeric substance in the liquid from which the foam is prepared. The lower the concentration of the polymeric substance in the liquid, the lower will be the rigidity and density of the coagulated foam. Additional variation is by variation of the amount of air whipped into the liquid foam as a liquid foam of high air content forms a light foam upon coagulation.

The coagulated foam may contain solid fillers such as pigments, clay, ground cork, wood flour or pulp, cotton fibres, asbestos, glass wool, and the like. Such materials are dispersed in the liquid or liquid foam prior to coagulation. The foam may also have dispersed therein or be impregnated with, water-resistant materials such as waxes, rubbers, resins and pitches. Paraffin is especially suitable. Preferably such materials are dispersed asemulsions in the liquid or liquid foam prior to coagulation. Mixtures of polymeric substances may be used in the foam. In addition, the foam may be modified by the incorporation of plasticizers by impregnation of the coagulate'ci foam or incorporation in the liquid foam.

The sealing member of the closure in accordance with this invention may consist entirely of coagulated foam or it may comprise coagulated foam with a facing or thin facing member of an impervious nature such as, for example, a coating of wax; a coating of cellulose derivative lacquer, resin, or varnish; a sheet of tin foil or lead foil: a sheet of resin-impregnated cloth, paper, or

fibrous sheeting; a him of cellulose derivative composition, vinyl ester polymer, or the like.

Container closures according to this invention have the advantage of an efficient seal due to the controllable resilience of the foam sealing member. The sealing member is impervious to oil, and inert with respect to foodstuffs and most commonly bottled fluids. The closure may be made entirely from inexpensive, readily available materials.

Hydrophilic foam substances are swelled somewhat by water. The present invention particularly includes a method of sealing materials comprising water in a container by providing a closure seal for the container of a hydrophilic waterinsoluble coagulated foam, whereby the water insures a tight seal by a swelling action on the foam.

What I claim as my invention is:

1. A container closure comprising a closure body adapted to hold a sealing member in sealing relation to a container opening and a sealing member of resiliently rigid cellular regenerated cellulose structure, the cells thereof being noncommunicating.

2. A container closure comprising a closure body adapted to hold a sealing member in sealing relation to a container opening and a sealing member of resiliently rigid cellular regenerated cellulose structure, the cells thereof being noncommunicating, and having a water repelling substance distributed therein.

3. A container sealing member comprising a resiliently rigid cellular regenerated cellulose structure, the cells thereof being non-communicating, with an impervious facing on surfaces exposable in use to the container contents, suitably shaped to engage and seal the opening of a container.

4. A container sealing member comprising a resiliently rigid cellular regenerated cellulose structure, the cells thereof being non-communicating, and having a water-repelling substance distributed therein, suitably shaped to engage and seal the opening of a container.

5. A container closure comprising a closure body having a sealing liner consisting of a resiliently rigid cellular regenerated cellulose structure, the cells of which are non-communicating, with an impervious facing on surfaces exposable in use to container contents.

6. A container sealing member consisting of a resiliently rigid cellular regenerated cellulose structure, the cells of which are non-communicating, suitably shaped to engage and sealthe opening of a container.

7. A method for preparing a container closure having a resilient sealing member which comprises casting a foam of a viscous solution essentially comprising a cellulose xanthogenate dissolved in aqueous alkali, in substantially the ultimate shape of the said sealing member, in a container closure member adapted to receive the foam and adapted to hold the sealing member in sealing relation to a container, and decomposing the cellulose xanthogenate in the cast foam to form by said decomposition a sealing member of resiliently rigid cellular regenerated cellulose structure, the cells'thereof being non-communicating.

ALFRED BURGENI.

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