US2079169A - Article of manufacture and method for making same - Google Patents

Description

Patented May 4, 1937 UNITED STATES PATENT ()FFH ARTICLE OF MANUFACTURE AND METHOD.

FOR MAKING SAlWE Delaware No Drawing. Application September 1, 1934,

Serial No. 742,473'

8 Claims.

This invention relates to the art of stainprevention, and, in particular, it pertains to the manufacture of regenerated cellulose caps and bands which resist staining when dried in place over bottle tops and the like.

Cellulosic bottle caps and bands, and in particular bottle caps and bands of regenerated cellulose, are now used on a large commercial scale. These caps andbands are applied to arbottle while they are still in a gel state, i. e. after coagulation and regeneration but before being dried, and are permitted to shrink in place by drying, thereby fitting tightly over and thus forming a seal for the bottle caps and bands. It has long been known, however, that when the gel caps or bands are dried downover cork stoppers or over closures comprising iron or alloys containing iron, the pellicles tend to become stained, and this condition seriously impairs the utility and salability of the caps and bands, particularly where the pellicles contain opaquing materials such as titanium oxide or other pigments.

An object of the invention pertains to the production of cellulosic pellicles which resist staining. A further object of the invention relates to the prevention of staining of bottle caps,

l bands and the like, when applied in the wet state to bottles and are permitted to shrink and dry in place, in contact with cork, iron or the like.

Other objects of the invention will appear here- .inafter.

It is believed that the staining of pellicles of regenerated cellulose and the like which are applied in the gel state and are permitted to shrink and dry in place over cork is due to the absorption of tannin, tannic acid and other related organic materials which are present in substantial amounts in cork. Iron stains are believed to arise from the fact that soluble compounds of iron are absorbed into and through the body of the caps or bands during the setting i thereof, that is to say, while the pellicles are being dried. In accordance with the present invention, in order to overcome the tendency towards stains, the pellicles are treated with an aqueous solution of a compound of the character specifically described hereinafter which dimin ishes or completely inhibits staining from cork or iron.

It is customary to ship gel regenerated cellulose bottle caps or bands in a dilute aqueous glycerin solution, the glycerin acting as a softener. The pellicles may be placed in the shipping container and the treating solution, containing the desired amount of glycerin and of stain inhibitor, is

then poured in until it covers the caps or bands, after which the container may be closed and shipped and the treated caps, whenever desired, placed on the bottles or like vessels and permitted to dry and shrink over the tops of the bottles. The caps or hands immersed in the shipping, solution soon come to equilibrium with the solu-- tion after absorption of a certain amount of the glycerin and of the stain preventing agent.

It has been discovered in accordance with this, invention that sodium aluminate, even in very small concentrations, imparts to the gel pellicles of regenerated cellulose a highly satisfactory resistance to staining.

The following example illustrates one mode of applying the principles of the invention:

A concentrated solution of sodium aluminate is prepared by adding 25 grams of solid NaOH to grams of an aqueous solution containing 50% by weight of A1(NO3)3.9H2O. A shipping container is filled with caps or bands of gel regenerated cellulose pellicles which have been given their final washing in soft water, and there is then added to the container, in an amount sufiicient tocover the pellicles, an aqueous solution containing the sodium aluminate solution diluted so that the solution, after reaching equilibrium with the pellicles, contains 1% aluminum nitrate and 0.5% caustic. Suflicient glycerine is added to yield about 6% glycerine in the equilibrium solution. The container may then be sealed and shipped tothe desired point, the pellicles being withdrawn when desired, the excess solution shaken ofi, the pellicles placed over the bottles, and shrunk in place. The dried pellicles applied either over cork stoppers or over iron, and dried, exhibit no appreciable staining.v

It has been further observed that when dyed caps are placed in a shipping solution of sodium aluminate, such as has been described, no substantial bleeding of the dye takes place, and no changes in the shade of the dyed caps could be observed after soaking in the solution for a week.

Care should be taken so that the sodium aluminate solution will not contain too much caustic. While the solutions need not be prepared with analytical precision, it has been found that sodium aluminate solutions containing 1% aluminum nitrate (calculated as A1(NO3)3.9H20) and 0.5% to 0.8% sodium hydroxide, have been found satisfactory to prevent the formation of either cork stains or iron stains. When using sodium aluminate having the proportion of aluminum nitrate to sodium hydroxide approximately within the ranges just given, the shipping solution may contain from a small fraction of a percent by weight upwardly of sodium aluminate although it is preferred that the amount used be between 0.5% and 5% sodium aluminate in the equilibrium solution.

While sodium aluminate represents the preferred form of the invention the invention contemplates the use of other water-soluble salts of aluminum, for example, potassium aluminate, similarly prepared. Instead of using aluminum nitrate as the source of the aluminum for reacting with caustic, other soluble aluminum salts may be used. Thus, a 0.64% by weight aqueous solution of A12S04.18H2O respectively were prepared and 0.5% by weight sodium hydroxide aqueous solution was added to yield a sodium aluminate solution equivalent to that referred to in the above example. These were effective in the same way, for the prevention of cork stains and of iron stains, as the sodium aluminate solutions prepared from aluminum nitrate.

Although the invention is of particular benefit when applied to regenerated cellulose pellicles prepared by the viscose process, it will be understood that it may be similarly applied to regenerated cellulose pellicles prepared from cuprammonium cellulose solution as well as from viscose, or it may be applied also to pellicles composed of other cellulosic materials prepared by Wet-casting methods, for example, cellulose esters such as cellulose acetate, and cellulose ethers such as glycol cellulose or ethyl cellulose.

While the invention is preferably applied to gel pellicles, it will be understood that the scope of the invention includes the treatment of pellicles which have been dried and then rewetted prior to treatment.

Moreover, it is to be understood that instead of shipping pellicles in a shipping solution, they may of course be removed from a shipping solution which has attained equilibrium, and shipped in a moist condition to the point of use.

Any variation or modification of the invention as described, which conforms to the spirit of the invention is intended to be included within the scope of the claims.

I claim:

1. The method of preventing the staining of regenerated cellulose pellicles, which comprises the step of incorporating in said pellicles a colorless water-soluble aluminate by absorption from an aqueous solution of said aluminate.

2. The method of preventing the staining of regenerated cellulose pellicles, which comprises the step of incorporating in said pellicles of sodium aluminate by absorption from an aqueous solution of said aluminate.

3. A pellicle of non-fibrous cellulosic material cast from an aqueous solution, said pellicle having incorporated therein a substantial quantity of a colorless, water-soluble aluminate, the said pellicle being characterized by its resistance to staining when placed in contact with iron or cork.

4. A pellicle of regenerated cellulose having incorporated therein a substantial quantity of a colorless, Water-soluble aluminate, said pellicle being characterized by its resistance to staining when placed in contact with cork.

5. A pellicle of non-fibrous cellulosic material cast from an aqueous solution, said pellicle having incorporated therein a substantial quantity of sodium aluminate, the said pellicle being characterized by its resistance to staining when placed in contact With iron or cork.

6. The method of preventing the staining of non-fibrous cellulosic pellicles cast from an aqueous solution, which comprises the step of incorporating in said pellicles a colorless, watersoluble aluminate by absorption from an aqueous solution of said aluminate.

7. The method of preventing the staining of non-fibrous cellulosic pellicles cast from an aqueous solution, which comprises the step of incorporating in said pellicles sodium aluminate by absorption from an aqueous solution of said aluminate having present a slight excess of caustic soda.

8. A pellicle of regenerated cellulose having incorporated therein a substantial quantity of so dium aluminate, such pellicle being characterized by its resistance to staining when placed in' contact with iron or cork.

ALBERT HERSHBERGER.