US2079147A - Method of treating pellicles - Google Patents

Description

4 in contact with Patented May- 4, 1937 UNITED srArss PATENT OFFICE METHOD OF TREATING PELLICLES Thomas F. Banigan, Kenmore, N. Y., assignor, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application "July 28, 1934,

Serial No. 737,428

iron stains, and in particular, it pertains to the treatment of pellicles of non-fibrous character, such as those made from regenerated cellulose,

. which are adapted for use as bottle caps, bands and the like, in order to prevent staining of the pellicles when dried in contact with iron or metals containing iron as a component.

Heretofore, when regenerated cellulose caps and bandsin a gel condition, i. e. after coagulation and regeneration but before being dried, were applied to bottles havingiron-containing metallic caps or appurtenances, a common defect has been that the cellulose caps and bands developed rust stains which appeared on the surface and greatly injured the appearance of the finished package. In addition, the portion stained with I rust became weakened and tended to crack at these points. l t

' Caps and bands of regenerated cellulose, which have been manufactured, for instance, by the viscose process, are customarily stored and shipped to consumers in an aqueous solution containing glycerin or other softener. The consumer withdraws thecap or band from the shipping solution and applies it over the bottle or other desired container or object and allows it to dry. Indrying, it shrinks considerably and grips the object tightly. If, in so doing, the cap orband comes into contactwith iron or metal containing iron, rust stains will develop, which impart'an unsightly appearance and a destructhe action to the cap or band. when the capor band is opaque, as for example when it contains-titanium oxide or other pigment as an 0 opaquing agent, the unsightliness due to the ironstain is quitepronounced. It is an object of this invention to produc non-fibrous pellicles which resist staining when 'further object of this invention to prevent iron stains in caps and bands of non-fibrous sheet materials which are applied in a gel state to hottles or other containers having iron-containing 5 metal caps or appurtenances, and which caps and bands attain their ultimate condition as the result ofshrinkage through the loss of moisture. other objects-of the invention will appear hereinafter.

- The objects of this invention are accomplished,

50 in the preferred form, by shipping the covering material in an aqueous solution containing a small amount of a stain-preventative material of the type herein described.

I have discovered that iron stains can be greatly 55 diminished and even completely prevented by v f the bottles.

'. The alkalinity of these compounds is somewhat iron-containing metals. It is a I 8Claims., (Cl .21538) This invention relates to the prevention of ping container and the treating solution containing the desired amount of glycerin and staininhibitor, then poured in until it covers the pel- 15 licles, 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 Those compounds found tovbe effective in pre- 20 venting iron-staining of pellicles of the character described herein are water-soluble compounds yielding an alkaline reaction in aqueous solution.

less than that of a sodium hydroxide solution of equal concentration, and is not so great as to injure the cellulosic pellicle during storage in a shipping container or when in place on a bottle.

Preferred compounds of this character which operate to prevent iron-staining of cellulosic-pellicles are tri-scdium phosphate (Na'sPCh) sodium pyrophosphate and triethanolamine. The scope of the invention includes the corresponding phosphates of the other alkali metals, e. g. potassium, and includes also other water-soluble salts which give a similar alkaline reaction in water solution such as borates and silicates of sodium and potasslum. The scope of the invention also includes water-soluble amines other than triethanolamine. 40

. The compounds used in accordance with the present invention need only to be soluble in water to the extent desired to inhibit iron-staining, e. g. so as to form a concentration ordinarily not less than about one-half per cent. Compounds which would otherwise be suitable but which have a too high or a too low pH, when dissolved in aqueous solution, may sometimes be used by adding buffer materials so that the final pH may be regulated within the desired limits, for example, to obtain a final pH corresponding to that of an aqueous solution of tri-sodium phosphate.

The 7 following illustrative examples describe modes of applying the invention: i

. Example I.Gel caps and/or bands of regenerated cellulose prepared from viscose and adapted to be applied to bottle tops and necks are packed in a shipping container containing glycerin and tri-sodium phosphate, in such a concentration that, after equilibrium with the moisture in the caps is reached, the shipping solution contains about 5% of glycerin and about /g% of tri-sodium phosphate.

Example II.-The same procedure is followed as in Example I except that the solution, when equilibrium has been reached, contains one to three per cent of sodium pyrophosphate. The caps and bands, when dried as in Example I, are almost completely free from rust stains after long periods of usage.

Example III.-The same procedure is followed as in Example I, except that the equilibrium solution contains 0.2% triethanolamine.

Caps and bands treated in accordance with the preceding examples, when dried down over iron or iron-containing metal bottle caps, even when the latter are filed down to expose the bare metal, remain completely free from rust stains even after a long period of time.

The proportion of anti-staining compounds present in the equilibrium solution which is used to ship the pellicles may vary from a fraction of a percent up to the limit of solubility of the compound in the solution. For most practical purposes, the equilibrium solution will contain from one-tenth per cent to five per cent of said compound.

The invention, in its preferred form, applies to the treatment of regenerated cellulose pellicles obtained from viscose, but it may also be applied to regenerated-cellulose pellicles obtained from cuprammonium cellulose solution, or to the treatment of cellulose esters such as cellulose acetate, or to cellulose ethers such as ethyl cellulose or glycol celluose which have been cast in water solution, or to pellicles of gelatin, casein and related substances. The invention may be applied wherein any such pellicles come in contact with aware"? a shipping solution which has attained equilibrium and shipped in a moist, condition to the point of use.

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

I claim:

1. The method which comprises treating nonfibrous cellulosic pellicles which are subject to shrinking by loss of water and which are subject to staining when shrunk in contact with iron with an aqueous solution of a salt which reacts alkaline in water solution and which will inhibit the formation of an iron compound which wili discolor said pellicles.

2. The method which comprises treating nonfibrous cellulosic pellicles which are subject to shrinking by loss of water and which are subject to staining when shrunk in contact with iron with an aqueous solution of an alkali metal phosphate.

I 3. The method which comprises treating nonfibrous cellulosic pellicles which are subject to shrinking by loss of water and which are subject to staining when shrunk in contact with iron with an aqueous solution of sodium triphosphate.

4. The method which comprises treating nonfibrous cellulosic pellicles which are subject to shrinking by loss of water and which are subject to staining when shrunk in contact with iron with an aqueous solution of sodium pyrophosphate.

5. A cellulosic pellicle which is subject to shrinking by loss of water and which is subject to staining when shrunk in contact with iron having associated therewith a colorless salt which reacts alkaline inwater and which will inhibit the formation of an iron compound which will discolor said pellicle.

6. A cellulosic pellicle which is subject to shrinking by loss of water and which is subject to staining when shrunk in contact with iron having associated therewith alkali metal phosphate.

'I. A cellulosic pellicle which is subject to shrinking by loss of water and which is subject to staining when shrunk in contact with iron having associated therewith sodium tri-phosphate.

8. A cellulosic pellicle which is subject to shrinking by loss of water and which is subject to staining when shrunk' in contact with iron having associated therewith sodium pyro-phos- D a e.

THOMAS F. BANIGAN.