US2122418A - Product and process of preparing same - Google Patents

Description

Patented July 5,1938

UNITED. STATES PATENT OFFICE PRODUCT AND PROCESS OF PREPARING SAME Ernest K. Gladding, Buffalo, N. Y., and Dorothy Bateman Maney, Old Hickory, Tenn., assignors, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application June 17, 1936,

Serial No. 85,768

V 22 Claims.

ucts containing large amounts of water or mis-;

ture. The invention also pertains to methods for producing such coated sheets or films. This application is a continuation in part of the application of Ernest K. Gladding and Dorothy E. Bateman, Ser. No. 731,603, filed June 21, 1934 for Product and process of preparing same.

Ordinary sheets or films of regenerated cellulose have been rendered moistureproof by coating with a moistureproofing composition comprising in its preferred form a fiowable solution of a cellulose derivative, a wax or wax-like material, a blending agent and a plasticizer. These coated sheets or films are very effective as a wrapping material for such products as bread, cake, candy,

or the like which it is desired to maintain in substantially their original fresh condition'without any'change in moisture content. Such coated sheets or films, when used as a wrapping material which is directly held in contact with products having an exceedingly high water or moisture content, such as butter, cheese, wet or frozen fish, ice cream or the like, and when such articles are kept over long periods of time in storage, have the disadvantage that the moistureproof coating tends to loosen and/or flake off from the sheet of regenerated cellulose and to thereby lessen the moistureproof quality of the wrapping material. It is an object of this invention to provide a flexible, substantially odorless, non-fibrous cellulosic'sheet or film having a surface coating which will adhere tenaciously to the cellulosic sheet or film. A further object comprises the production of films of this character having a moistureproofing coating comprising a cellulose derivative, a wax or wax-like material, a blending agent and a plasticizer. A still further object of th'e'invention comprises a simple, workable process, directly applicable to existing equipment, such as is used for the manufacture of regenerated cellulose sheets or films, for producing products having the'characteristics described A further object of the invention resides in the production of transparent, flexible, non-fibrous, cellulosic sheets or films prepared by precipitation from an aqueous cellulosic dispersion, coated 55 and/or sized. with an amino polymer, and having a moistureproof surface coating which remains firmly. anchored to the cellulosic sheet or film even when in direct contact with water over long periods of time.

A specific object of the invention resides in the 5 production of transparent, flexible, substantially odorless, non-fibrous cellulosic sheets or films prepared by precipitation from an aqueous cellulosic dispersion, coated and/or sized with a de-acetylated chitin, and having a moistureproof sur- 10 face coating which remains firmly anchored to the cellulosic sheet or film even when in direct contact with Water or moisture over a prolonged period of time.

Other objects of the invention will appear from 15 the following description.

These objects are accomplished by the following invention which, in its preferred form, contemplates forming a cellulosic sheet or film, applying to said sheet or film a surface coating having moistureproofing characteristics and applying directly to the cellulosic base and intermediate said base and the surface coating, a coating and/or sizing of an amino polymer and preferably of a de-acetylated chitin. 25

The following examples illustrate modes of applying the principles of the invention.

Example I i A sheet of regenerated cellulose in the gel state.; 30 which has been cast from viscose, desulfured, bleached, and washed free from impurities in the usual manner on the casting machine and is ready for the glycerin treatment, is led through an aqueous glycerin bath, which, in addition to- 5 4 per cent by weight of glycerin, also contains one per cent by weight of a de-acetylated chitin, and-0.28 per cent by weight of acetic acid (calculated as 100 per cent acetic acid).

Acetic acid is used in order to render thedeacetylated chitin soluble. In this example, the acetic acid used corresponds to 75 per cent of the amount of acid theoretically required to completely react with the de-acetylated chitin used when a ratio of 161 to 60 is employed to express the relation of de-acetylated chitin to acetic acid in terms of molecular weights.

The sheet of regenerated cellulose is held in contact with the aqueous solution of the salt of de-acetylated chitin and glycerin for from 10 to 20 seconds after which the excess solution is removed from the sheet by means of squeeze rolls which reduce the water content of the sheet to between three and four times the weight of the cellulose, after which the sheet of regenerated whichhas been treated with the aqueous glycerin solution containing .the size (the de-acetylated chitin) may be carried out according to the usual method for drying regenerated cellulose sheeting on the casting machine by bringing the sheet directly from the squeeze rolls into contact with heated rolls which dry the sheet at temperatures preferably between 50 and 90 degrees centigrade. However, there may be a tendency for the size to be deposited on the dryer rolls when they become wet with the solubilized de-acetylated chitin from the wet fihn passing over them. This deposit, resulting from the heat acting on the soluble size, may flake off from time to time on the fresh film passing over the dryer rolls, thereby imparting a faintly mottled appearance to the finished film.

Therefore, in this preferred example, the regenerated cellulose sheet, wet with a solution of glycerin and the size, after passing through the squeeze rolls and beforecomingi into contact with the dryer rolls, is first given a preliminary partial drying out of contact with any surface by passing the sheet through air heated to an elevated temperature by means of any suitable arrangement, whereby the moisture content of the sheet is reduced to any desired extent, for instance, from one-tenth to one-half of its initial water content before coming in contact with the dryer rolls of the casting machine to complete the drying operation in the usual manner.

The resulting sheet of regenerated cellulose coated or sized with an insoluble deposit of deacetylated chitin may be conditioned if necessary to bring it to the desired moisture content and is then coated with a moistureproofing composition of the following formula:

Parts by weight Py y Gum damar 4.64 Dibutyl phthalate 2.80 Paramn, M.P. -61 C 0.48 Zinc stearate 0,15 Ethyl acetate 56.34 Toluene 28.53 Alcohol 3.20 Acetone 0.11

The sheet is passed through the moistureproofing composition, the excess of which is removed by desired moisture content. The resulting product is a sheet of regenerated cellulose with a moistureproofin'g coating, which is substantially odorless, transparent, flexible, and moistureproof,

' and to which, by virtue'of the sheet being coated or sized with a de-acetylated chitin, the moistureproof coating adheres or is anchored very tenaciously when the sheet is in direct contact with water or is used as a wrapping directly in contact with products containing large amounts of water or moisture such as butter, cheese, wet

e ails or frozen fish, ice cream, or the like, for very substantial periods of time, for example, for a month or more.

Example I! A sheet of regenerated cellulose in the gel state is passed through an aqueous bath containing 4 per cent by weight of glycerin, 0.7 per cent by weight of a de-acetylated chitin, and 0.2 per cent by weight of formic acid, or any other amount of formic acid sufiicient to render the size water-soluble.

In this example, the amount of formic acid used is 80% of that theoretically required to completely react with the de-aeetylated chitin to form the desired formate, assuming the molecular ratio of de-acetylated chitin to formic acid to be 161 to 46.

After being held in contact with this bath for 10 to 20 seconds, the cellulosic sheet is freed from excess solution by means of squeeze rolls so that the water content of the sheet is between three and four times the weight of the cellulose and the sheet is then dried either by being led directly over heatedrolls, or as in Example I, by means of a preliminary partial drying in hot air out of contact with any surface, followed by passage over dryer rolls to complete the drying. In either case the drying of the sheet may be accompanied by a treatment with gaseous ammonia which facilitates the conversirn of the water-soluble formate salt of the de-a'cetylated chitin to an insoluble product.

A moistureproofing coating is applied to the sheet of regenerated cellulose treated as described above in this example by passing the sheet through a bath comprising ethyl cellulose, a wax, a blending agent and a plasticizer, re-

moving the excess moistureproofing bath and removing the solvent at a temperature above the melting point of the wax, after which the coated,

ties which have been'described for the moistureproof film produced in ple I. 1

" Example III A finished or dry sheet of glycol cellulose is accordance with Exampassed through an aqueous solution containing 0.5% by weight of de-acetylated chitin which has been converted to the acetate by acetic acid in an amount which is 0.15% by weight of the 1 aqueous solution (calculated on the basis of acetic acid). After removing the excess solution from the sheet in any suitable manner, the sheet is dried at 80 degrees centigrade and subsequently coated with a moistureproofiing composition comprising a solution of nitrocellulose, gum darnar, paraffin and dibutyl phthalate. The excess moistureproofing material and the solvent may be removed as described in the preceding example.

Example IV The diethylaminoethyl methacrylate polymer produced in accordance with the procedure outlined in Example B (below) is dissolved in dilute acetic acid containing 5-6% glycerol to form a solution containing 0.25-1.00% of the resinous polymer, sufiicient acetic acid being used to just solubilize the polymer. Sheets of gel regeneratedcellulose film 'are immersed in this solution and allowed to remain'five'minutes, whereupon they are removed and the excess solution drained oil. The sheets are thendried in an oven at C.

Sufilcient beta-amino ethoxyethyl cellulose to form a 2% solution is dissolved in an aqueous mixture containing 1.5% acetic acid and glycerol. Sheets of gel regenerated cellulose film freed-from excess water are immersed in this solution at room temperature for 5 minutes, after which they are removed and allowed to drain, the excess of the rather viscous solution being scraped oil? by means of glass rods. The treated film is then placed on a drying frame and dried in an oven at 120 C. for minutes. The dry film is then coated with a moistureproofing lacquer in the usual manner to produce a clear,

"transparent, flexible and moistureproof product.

agent.

The anchorage of the moistureproofing coating is equal to or better than that obtained through the use of deacetylated chitin as the anchoring Example VI An aqueous solution containing 2% of diethylamino methyl zein is prepared by dissolving the amino polymer in dilute acetic acid containing 0.28 partsof acetic acid for each part of the zein derivative and 56% glycerol. Films of gel regenerated-cellulose are treated as in the preceding examples. the drying time being 30 minutes at 120 C. The anchorage obtained after moistureproofing is somewhat inferior to that obtained through the use of de-acetylated chitin alone. The use of a 1% solution of the zein derivative results in some improvement in the anchorage and the use of a combination of 1% solution of the zein derivative and 1% solution of deacetylated chitin produces anchorage results which are better than those obtained with either whe used alone in 2% concentration,

Example VII An aqueous solution containing 2% plperidyl methyl zein is prepared by dissolving in water containing 0.28 part of acetic acid per part of above and coated with a moistureproofing composition shows an improved anchorage which, thoughinferior to that of de-acetylated chitin is quite satisfactory.

Eaiample VIII 'A 2%- solution of the phenol-formaldehydedimethylamine resin (Example E below) is prepared by dissolving the resin in an aqueous solutlon containing 1.5% acetic acid and 6% glycerin and this solution was used as a treating bath for regenerated cellulose film. The treated film is dried for 30 minutes at 120 C. and the moistureproof product shows anchorage approximately equal to that of de-acetylated chitin with some improvement over the latter when the anchorage tests were made in water containing 0.1% acetic acid.

Example IX Q A meta-creso1-dimethylamine-formaldehyde resin similar to the resin described in Example E (below) is dissolved in dilute acetic acid con-'- final material taining 5-6% glycerol to form a solution containing 2% of the resin. When used as the anchoring agent, as in the preceding examples, the results obtained are comparable to those obtained with deacetylated chitin. A 1% solution of the Example X A dicyclohexyl amino ethyl methacrylate prepared in a manner similar to that described in Example B (below) may be used in either its monomeric or polymeric forms. Mixtures of the monomer and polymer have been-found to be particularly useful, the resinous material being brought into solution by means of dilute acetic acid. A 2% solution is capable of producing a which will show an anchorage approximately equal to that of the de-acetylated chitin. The anchorage can be improved somewhat by using as the anchoring agent a combination of these monomers and/0r polymers with de-acetylated chitin.

This invention contemplates, as a base, any smooth, dense, non-porous, non-fibrous cellulosic sheet or film which may be precipitated from an aqueous cellulosic dispersion. Thus, the scope of the invention includes the use of sheets or films of regenerated cellulose, whether precipitated from solutions of viscose, cuprammonium cellulose, or any other aqueous solution or dispersion of cellulose, and it also contemplates the use of sheets or films of such cellulose esters and ethers as are precipitated from aqueous solutions or dispersions, such as glycol cellulose, cellulose glycolic acid, methyl cellulose and ethyl cellulose of low alkyl content, cellulose phthalate, and

other cellulose products similar to those described. When any given coating composition is applied to such cellulosic sheets or films, the coating composition will not penetrate therethrough and will normally result in a surface coating. It is desired to emphasize the fact that the preferred form of the invention is directed to the treatment of regenerated cellulose sheets or films since it is in this form that the invention may be applied with the greatest advantages.v

As a surface coating, the invention contemplates the use oi any coating composition containing a cellulose derivative base, such as cellulose nitrate, cellulose acetate, ethyl cellulose, benzyl cellulose or the like, which may be. modified as desired by the addition of blending agents, waxes, plasticizers, et cetera. In its preferred form, this invention contemplates as a surface coating a moistureproofing coating comprising a cellulose derivative, a wax or wax-like material or other moistureproofing agent, a blending agent and a plasticizer. .Such moistureproofing compositions are disclosed in Charch and Prindle U. S. Patent No. 1,737,187, issued November 26, 1929.

The invention also contemplates the anchoring to. a cellulosic base of moistureproofing coatings which may not contain cellulosic material, e. g.. rubber-wax or resin-wax coatings, and includes also the anchoring of coatlngswhich may conceivably be used for purposes other than mois-' acetic 'acid. The amino nitrogen maybe primary, secondary or tertiary, part of an open chain or of a cyclic molecular structure.

The amino polymers which may. be used a anchoring agents, as illustrated in the above examples, may be subdivided into several groups as follows:

1. The first group, closely related to though nevertheless distinct from cellulose, may be considered as hexose amine polymers, or more broadly as carbohydrate amine polymers, which have, where necessary, been purified and converted into the acid soluble type. With or without such treatments, the highly polymeric molecule is built up by nature, and the amine nitrogen, as'a rule, is present in the natural product. Those in which the nitrogen is present in the substance as it exists naturally may be of marine or insect origin on the one hand, or vegetable origin on the other. De-acetylated chitin, which is by far the best example of a nexose amine'polymer is; for example, of marine origin, and the polymers obtained from fungi such as aspergillus niger are of vegetable origin. .Examples of carbohydrate amine polymers in-which the highly polymerie molecule has been built up by nature, but int-o which the amine nitrogen has been introduced syntheticallyare the alkylamin-o celluloses. Regardless of the source of the nitrogen, this first group also includes various reaction products and chemical derivatives of carbohydrate amine polymers, provided of course that they have the required solubility characteristics. 7

2. The second group of amino polymers coinprises that group of synthetic resins, in the making of which ammonia in someinstances and monomeric amino nitrogen containing bodiesin others have beenemployed. Thisgroupis distinct in that the highly polymeric molecules are built up wholly by artificial means, i. e.,.they are not synthesized by nature. The resins of this group may be considered broadly as those which contain amino nitrogen and have the requisite solubility characteristics. The following types oi resins are illustrative of the classes among which highly polymeric amino nitrogen containing bodies falling' in this classification may be found. (a) Resinous polymeric amino alcohol esters of acrylic acid and of its homologues substituted in the alpha position bya hydrocarbon radical, and (b) resinous reaction products of phenols, aldehydes and ammonia or primary or secondary amines.

(a) Examples of' the first of the above sub-- classes of resins are beta-diethylaminoethyl alpha-methacrylate, beta piperidyl N ethylalpha methacrylate, and beta dicyclohexyl aminoethyl alpha-methacrylate' These resins may be prepared by spontaneous polymerization of the monomeric compounds, but for the purposes of the present invention, advantage can be taken of a unique property of the monomers, namely their ability to form polymerizable salts with aqueous acids. The monomer as prepared may simply be dissolved in the stcichiometrical amount or more of aqueous acid and the solution heated with a polymerization catalyst such as benzoyl peroxide until polymerization of thesalt is effected.

(b) An example of the second of the above subclasses of resins having amino nitrogen and the specified'soluisilities is the reaction product of meta-cresol, formaldehyde and dimethylamine. Other phenols sueh as phenol itself or p-tertiary amyl phenol may be substituted for the cresol, and the ammonia or various primary or secondary amines for the dimethylamine. It is desirable in most cases, possible in all caseaand necessary in some cases, to react the amineor ammonia with a part of the formaldehyde before adding the remainder. These resins are to be sharply distinguished from the phenol-aldehyde resins prepared in the presence of only catalytic amounts of ammonia or amines, which resins cannot be employed in accordance with the methods of this invention because they lack the pre ponderance oi amino nitrogen which induces the proper solubility characteristics. The' molal ratio of amine to phenol which is used in making the resins with which the present invention is concerned is on the order of 1:2.

3. The third group of amino nitrogen containcohol, preferably the latter. To the alcohol solution is added aqueous formaldehyde, a secondary amine and suificient alcohol torkeep the concentration at about the original figure. The mixtureis allowed to stand or maybe heated gently'until it becomes soluble in acetic acid, 6-18 hours, depending on temperature, usually being required. The final product, in order to be acid soluble, should have at least 8-10%basic amino nitrogen. The maximum obtainable is around 22% and the products having the high percentages are the most desirable for use in the present invention. Examples I to Hi are directed to the use of a de-acetylated chitin as an anchoring agent for the moistureproofing coating. Chitin is an acetylated carbohydrate aminepolymer, and may be, for convenience, termed chitose amine polymer, and after, the removal of the acetate, as by saponification, the product, which is believed to be a carbohydrate amine polymer, is capable of re-- acting with acids to form salts. The de-acetylated chitin referred to in the examples given above, may be prepared as described in the Rigby U. S. Pat. No. 2,040,879, issued May 19, 1936, one method or preparation being described as follows:

Example A Shrimp, lobster or crab shells are treated first with a 1% solution of soda ash at boiling temperature for about six hours, after which the liquor is drained at! and the shells washed with water until free of alkali as tested byphenolphthalein. The washed shells are then subjected fer a period of time to treatment with a 5% hydrochloric acid solution until all lime salts have been removed (10 to 12 hours at ordinary temperatures). After washing with water to remove the acid, the shells are given a second treatment with a soda ash solution containing about 0.02% ordinary soap, the treatment being carried out at-the boiling temperature of the solution for a period of about 8 hours. After-this treatment the shells are drained free of the liquor and water-washed until free of alkali as tested by phenolphthalein, whereupon they are centrifuged to remove as much water as possible. The shells are then treated with 40% sodium hydroxide at ,110 degrees centigrade for about four hours, after after drying at 65 degrees centigrade, may be used to prepare solutions in acids as desired.

The chitin may be partially or completely deacetylated depending on the conditions present during the de-acetylation. Themore complete the de-acetylation, the more soluble is the salt produced by reacting with acid.- Thus chitose amine polymer, from which the acetyl substituent some degradation of this chitose amine polymer takes place and the extent of degradation increases as the de-acetylation becomes more complete. must be a balance established between the completeness ofde-acetylation and the degradation of the de-acetylated product. For ordinary purposes, it will be sufiicient to use a'product prepared from chitin which has been 85 to 90 per cent de-acetylated. It will be understood that this range of de-acetylation is not limitative since chitin, which has been de-acetylated to an extent as low as 50 per cent or lower or as high as 100 per cent, may be used with advantage.

It has been stated that chitin is believed to be an acetylated carbohydrate amine polymer. This is in accordance with the evidence present ed in the literature. It is alsobelieved to be an acetylated mixed or cross or inter-polymer of two carbohydrate amines. We do not wish, however, to be limited to theory, but cover the use of the de-acetylated chitin regardless of its ultimate molecular composition.

While the de-acetylated chitin is the preferred form of anchoring agent for the coating which is used for the cellulose film, the invention also contemplates the use of other carbohydrate amine polymers such as chondrosin which may be obtained by the de-acetylation' of chondroitin -(believed to be an acetylated carbohydrate (chondrose) amine polymer and which is obt'ainable from animal cartilage in a manner a made soluble by causing it to react with any one of a larger number of acids including acetic, formic,

' citric, glycolic, malic, maleic, succinic, adipic,

phtha-lic, tartaric, benzoic and hydrochloric acids, and the, like. Coatings or films prepared from aqueous solutions of these water-soluble salts, upon beingdried, preferably at an elevated temperature, are more or less rapidly rendered insoluble both in water and in organic solvents.

In the case of salts formed by reacting with volatile acids, particularly volatile acids which are only slightly ionized, like acetic acid, the conversion to insolubility is easily and quickly accomplished since the acid, being weak or slightly ionized is readily dissociated from its salt and being volatile is easily removed by heat, leaving. an insoluble residue. Salts formed from the nn-volatile acids and/or from the highly ionized acids are much less readily converted to insolubility, and consequently in the practice of this invention, it is preferred to use salts of the de-acetylated chitin and of volatile acids of Thus, for purposes .of expediency, there.

acids, these salts may be convertedinto the insoluble form by treatment with ammonia, as, for

example, in the form of gaseous ammonia (see,

Example II).

Any suitable concentration of de-acetylated chitin may be employed in the aqueous solution of its salt, depending upon the method of operation used and the amount of size which it is desired to have present in the'finish'ed cellulosic sheet. In general, it is preferred to use solutions in which the concentration of the de-acetylated chitin salt is equivalent to between 0.2 and 2.0 per cent by weight. As .has been stated, however, higher or lower concentrations may be desirable at times for different eflects or'with different methods of applying the size. The amount of size present in the finished celulosic sheet is controlled by the concentration of deacetylated chitin salt in the solution and by the amount of this solution removed from the wet sheet by squeeze rolls or by other means, prior to the drying of the sheet. In the preferred form of this invention, this amount ranges from 0.5 to 4.0 per cent of the weight of the sheet, although it may at times be desirable for certain purposes to have present in the sheet an amount of size greater or less than those included within these limits.

The preparation of various amino polymers is fully discussed in Rigby U. S. Patent No. 2,040,- 879, issued May 19, 1936, relating to the preparation oi de-acetylated chitin; .and in a number of copending applications such as for instance, Graves Serial No. 21,807, filed May 16, 1935 relating to polymeric amino alcohol esters of alpha substituted acrylic acid; Harmon Serial No. 21,- 810, filed May 16, 1935, relating to polymeric salts of amino alcoholic esters of alpha substituted acrylic acid; Meigs Serial'No. 59,643, filed January 17, 1936, relating to amino proteins; Hardy Serial No. 61,842, filed January 31, 1936, relating to amino celluloses soluble in dilute acetic acid; Haskins Serial No. 61,806, filed January 31, 1936, relating to alkylamino celluloses soluble in at least a stoichiometrical amount of 5% aqueous acetic acid; Baithis Serial No. 69,725, filed Mar. 19, 1936, relating to the resin prepared by reacting vinyl ketone polymers such as methyl vinyl ketones with ammonia or a primary amine; Greenewalt Serial No. 69,723, filed Mar. 19, 1936, relating to hydrogenating ketone resins in the presence of ammonia or a primary or secondary amine; and Harmon & Meigs Serial No. 85,820, filed June 17, 1936, relating to the preparation of amine-phenol-aldehyde resins.

To further illustrate the preparation of a few of'thes'e amino polymers the following examples are given.

Example B distilled until all the moisture present in the reagent has been removed. Beta-diethylaminoethyl methacrylate is isolated by collecting the fraction boiling at 85:5 0. at 5 mm. pressure,

carefully washing 8 times with cold water to remove traces of p-phenylene diamine, drying with anhydrous magnesium sulfate, filtering, washing the drying agent with ether, combining the washings wi h the bulk of the product and then distilling the ether under reduced pressure in an atmosphere of nitrogen. The monomeric ester is left in the distilling glass as an almost colorless liquid which polymerizes spontaneously to a tough, transparent, pale amber polymer. When allowed to stand at room temperature or even at a lower temperature, the polymer was insoluble in water and in the common oxygenated organic I solvents, soluble in acetone.

Example C To a solution of 220 ccs. of formalin (37% aqueous formaldehyde) containing 1 gram of potassium carbonate, there is added 250 ccs. piperidene while the mixture is cooled with tap water. This methylolpiperidene solution is then added to a mixture of 1,500 ccs. of methanol, 75 cos. of water, and 250 grams of zein. The solution is mixed thoroughly with mechanical agitation and allowed to stand over night. It is centrifuged to remove insoluble materials and then concentrated in vacuo: The concentrated Fifty grams of polymeric methyl vinyl ketone are dissolved in 250 grams of dioxan and agitated overnight with grams of cyclohexylamine. A test showed that the resin was not readily soluble in dilute acids; hence, the reaction mixture is heated in a steam bath for 5 hours. The resin is then precipitated. By pouring the reaction mixture in water and after standing 12 hours in fresh I phenol.

water, it is filtered and dried in vacuo, The yield is 55 grams. The pulverized resin is soluble to the extent of 4 grams in 96 gramsof 5% aqueous solution of acetic acid.

Egcample' E 1 A solution of -18 grams (0.4 mol.) of dimethylamine in 32.4 grams (0.4 mol.) of 37% aqueous formaldehyde was added with mechanical stirring and cooling to 53.5 grams (0.5 mol.) of 88% To the above mixture, a solution of 81 grams (1 mol.) of 37% aqueous formaldehyde and 30.4 grams (0.5 mol.) of 28% aqueous ammonia was added with cooling. The resulting solution was gradually heated in a water bath to 90 C. and held at that temperature for 5 hours. The resulting resin was purified by grinding it to a uniform slurry in the presence of a little water in an ice cold mortar, followed by filtration and washing with ice cold water. After drying, it weighed 74 grams. It was a yellow material which softened slightly above room temperature. It was soluble in acetone, ethyl acetate, dioxan, 10% aqueous sodium hydroxide, 1.5% aqueous acetic acid, 3%- formic acid, and 90% toluene-10%ethanol mixture.

There are of course numerous other amino polymers that can be prepared in much the same way as will be apparent from a study of the'applications specifically referred toabove,suchasfor instance beta-dimethylaminomethyl methacrylate; beta-dicyclohexylaminoethyl methacrylate;

beta-di-N-butylaminoethyl methacrylate; betamorphollne-N-ethyl methacrylate; triethanolamine monomethacrylate; dimethylaminomethyl v aniline; and many others.

- Instead of simple polymers, interpolymers may be prepared, for instance by reacting methyl methacrylate and methyl vinyl ketone in the presence of ammonium hydroxide or reacting beta-cyclohexylamino'ethyl methacrylate monomer and beta-dimethylaminoethyl methacrylate monomer together under suitable conditions. Other equivalent polymeric materials such as c0- polymers may also be used, provided their solubility characteristics are as previously set forth. In order that the finished cellulosic sheet may be of the desired degree of softness, a softening agent, such as glycerin, is incorporated in the aqueous solution of the size. The aqueous solution may be applied to the cellulosic sheet by immersing the sheet in the solution or by brushing or spraying the solution onto the sheet, or by applying the solution to the sheet by rollers or by any other convenient means. Moreover, the size solution may be applied either to the cellulosic sheet in the gel condition orto the finished dry cellulosic sheet by another operation. We prefer, however, to apply it to the gel sheet from the glycerin bath. In the step of drying the cellulosic sheet treated with a solution of the size, for example, the acetate of de-acetylated-chitin, in which step the soluble salt is converted to an insoluble coating or sizing on the sheet, a wide range of temperature is possible. We prefer,

however, to carry out the drying operation at temperatures between 50 degrees and 90 degrees centigrade. In certain cases, as has been stated in the preceding paragraph, vapors of basic compounds, such as ammonia, may be losic sheet, which has been dried or partiallydried after the application of the solution of the size, with a solution of a basic compound, such as dilute ammonium hydroxide, a solution of ethylene diamine, or of triethanolamine or the like.

As has been stated, the greatest advantages follow from the use ofde-acetylated chitin as an anchoring agent for moistureproofing coatings applied to regenerated cellulose or to other cellulosic films of the character described. It will be understood that it can in general be used to anchor coatings for transparent cellulosic sheeting where such coatings have less or greater moistureproofing properties than those described in the examples given above.

, periods. of time.

The present invention effects the production of flexible, substantially odorless, non-fibrous, nonporous cellulosic sheets or films having a moistureproofing coating securely anchored to the film base and resistant to deterioration when subjected to the action of liquid water over long Further advantages are the adaptability of the process of the invention to equipmentnow used for the production of regenerated cellulose film and the like, without necessitating a substantial change in the design of such equipment; lower cost, minimum waste and great efficiency. Where no pigment is used, the composite films have a high degree of transparency.

The term "de-acetylated chitin, as used in the claims, is intended to include the product which is prepared by removing the acetyl groups from chitin in any suitable way. Unless otherwise qualified, the term also includes the product we pared by solubilizing the de-acetylated chitin, as, for example, by forming a salt with an acid, and

by .again'insolubilizing. It is also intended to include any other product substantially identical therewith; as, for example, where such product is produced synthetically.

In some instances the dried cellulosic sheet coated or sized with de-acetylated chitin may retain a very faint trace of the characteristic odor of the acid used in forming the water-soluble salt. This trace of odor may readily be removed by treating the sheet with dilute vapors or a dilute solution of a basic compound like ammonia to neutralize the acid, by volatilizing the acid by means of heat, or by a current of air or steam, or by any known deodorlzing treatment. If desired, the aqueous solution of the size may be subjected to treatment with activated carbon in order to remove any undesirable odor.

While the invention has been described particularly with respect to transparent wrapping tissues, itwill be understood that within its broad scope, the invention includes the anchoring of coatings to sheets which are thicker than wrapping tissues. The invention is also applicable to the anchoring of coatings to tubes, sausage casings, bottle caps and bands, molded articles, and, in general, to any articles of cellulose or similar material of the character described, where the problem of anchoring coatings arises.

The preferred form of the invention resides in the anchoring of moistureproofing surface coatings to a non-porous, non-fibrous base such as regenerated I cellulose. scope, the invention comprehends also the coating of other bases, e. g., rayon fabric and the like,

in order" to anchor surface coatings thereto. Even where the coating of the base, whether it be non-porous or of other character, is discontinuous in character, such, for example, as in the printing of colors, symbols, indicia, advertisements, etc., the de-acetylated chitin may be used as the anchoring agent. Thus, regenerated cellulose sheets, tubes, caps, sausage casing, etc., when coated or sized with de-acetylated chitin may be printed with printing ink either having a lacquer base-or a drying-oil base, to give any desired indicia, and, after drying, the printing re mains securely anchored to the base even after being subjected to rigid washing, boiling or other processing steps.

Additionally, the present invention may be used to improve the anchorage of various coatings to bases other than those specifically noted above, for example, paper, cotton cloth, and

Within its broadest other bases which are water sensitive, i. e., will absorb water, the anchoring agents improving the adhesion between the coating and base over that exhibited where the coating is applied to the basein the absence of the anchoring agent.

The invention also contemplates the production of coated self-sustaining films of de-acetylated chitin formed by casting or otherwise forming the de-acetylated chitin into the desired form and then applying a coating.

For the purposes of this invention, moistureproof materials are defined as those which, in the form of a thin,,continuous and unbroken film, will permit the passage of not more than 690 grams of water vapor per 100 square meters per hour, over a period of 24 hours at approximately 395 C.:0.5 C., the relative humidity of the atmosphere at one side of the film being maintained at least at 98% and the relative humidityoi' the atmosphere at the other side being maintained at such value as to give a humidity differential of regenerated cellulose of thickness approximately 0.0009", will produce a coated product which is moistureproof.

A moistureproofed regenerated cellulose sheet is capable of resisting the passage of moisture or water vapor at least ten times as effectively as the uncoated regenerated cellulose sheet.

Parts, proportions and/or percentages referred to throughout the specification and claims are to be construed as parts, proportions and/or percentages by weight unless indicated otherwise.

Any variation of or modification of the invention, as it has been described above in this application, which conforms to the spirit of the inven tion, is intended to be included within the scope of the claims.

We claim: I

1. An article of manufacture comprising a watersensitive base, a surface coating and an intermediate coating comprising an amino polymer which is substantially insoluble in water and in 5% aqueous ammonia but soluble in 2% aqueous acetic acid.

2. An article of manufacture comprising a water-sensitive non-fibrous base, a surface coating and an intermediate coating comprising an amino polymer which is substantially insoluble in water and in 5% aqueous ammonia but soluble in 2% aqueous acetic acid.

3. A composite film suitable for use as a wrapping tissue comprising a water -sensitive, nonfibrous base, a surface coating and an intermediate coating comprising an amino polymer which is substantially insoluble in water and in 5% aqueous ammonia but soluble in 2% aqueous acetic acid.

4. A composite film suitable for use as a wrapping tissue comprising a water-sensitive, nonfibrous base, a moistureproofing coating and an intermediate coating comprising an amino polymer which is substantially insoluble in water and in 5% aqueous ammonia but soluble in 2% aqueous acetic acid.

5. In a process for producing an article comprising a water-sensitive base and a surface coating which adheres tenaciously to the'base even when in contact with water over long periods of time, the steps which comprise applying to the assigns base an intermediate coating comprising an a de-acetylatedchitin, and; a surface coating amino polymer, which is substantially insoluble in water and in aqueous ainmonia but soluble in 2% aqueous acetic acid, then applying a surface coating;

6. In a process for producing an article comprising a water-sensitive, non-fibrous base and a surface coating which adheres tenaciously to the base even when in contactwith water over long periods of time, the steps which comprise applying to the base an'intermediate coating comprising an amino polymer which substantially insoluble in water and in5% aqueous ammonia but soluble in 2% aqueous acetic acid, then applying a surface coating.

7. A composite film suitable for use as a wrapping tissue comprising a non-fibrous cellulesic sheet; an intermediate coating comprising a sieacetylated chitin, and a surface coating said sheet and said surfacev coating exhibiting an adhesion greatly improved over that exhibited between a similar sheet and surface coating when in direct contact with each other, said adhesion being tenacious even when the composite film is subjected to contact with Water over a long period of time.

8. A composite film suitable for use as a wrapping tissue comprising a sheet of regenerated cellulose, an intermediate coating comp-rising a deacetylated chitin, and a surface coating.

9. A composite film suitable for use as a wrapping tissue comprising a sheet of regenerated cellulose, an intermediate coating comprising a deacetylated chitin; and a surface coating comprising a meistureproofing composition.

19. A composite film suitable for use as a wrapping tissue comprising a non-fibrous cellwosic sheet, an intermediate coating of a de-acetylated chitin, and a surface coating which contains a cellulose derivative base, said sheet and said surface coa ting exhibiting an adhesion greatlyimproved over that exhibited between a similar sheet and surface coating when in direct contact with each @other, said adhesion being tenacious even when @the composite film is subjected tocontact with water over a long period of time.

able for use as a wrapping tissue, the steps comprising applying an aqueous solution of a'solubilized de-acetylated chitin to a sheet of regenerated cellulose, (trying the treated sheet. and then applying a moistureproofing surface coating. 7

12. A composite film suitable for use as awrapping tissue comprising a sheet of regenerated celluiose, an intermediate coating of a member of the class consisting of de-acetylated chitin and de-acetylated chondroitinand a surface coating.

13. A printed article comprising a water sensitive base having printing thereon and provided with an anchoring agent for the printing comprising a de-acetyiated chitin.

14. A nioistureproof composite film suitable for i use as a wrapping tissue comprising a sheet of regenerated cellulose, an intermediate coating of 11. In a process for preparing a product suit V a surface coating.

' of a de-acetylated chitin and an acid.

comprising a moist'nreproofing cellulose deriva-' a baseand surface coating which exhibit a greatly improved adhesion of such a character as to remain tenacious when subjected to contact with water over long periods of time, the steps which comprise applying a coating comprising a solution of de-acetylated chitinio a non-fibrous, cellulosic'sheet, drying the sheet, and then applying 16; The process of claim 15 characterized in thatthe solution is an aqueous solution of a salt 1'7. The process of claim 15 characterizedin that the solution is an aqueous solution of a salt of a de-acetylated chitin and an acid, said solution also containing a softener for the cellulosic sheet. r

-18. The process of claim 15 characterizedin that the solution is an aqueous solution of a salt oga de-acetylated chitin and an acid, and further characterized in that the sheet is treated with a basic material prior to applying the surfacecoating.

,19. The.process of claim 15 characterized in that the solution is an aqueous solution of a salt of a de-acetylated chitin and an acid, and further characterized in that the sheet is treated with gaseous ammonia during drying.

20. A composite article comprising a watersensitive base, an intermediate coating of the ciass consisting of de-acetylated chitin and deacetylated chondroitin, and a surface coating, said base and said surface coating exhibiting an adhesion *greatly improved over that. exhibited between a similar base and surface coating when in direct contact with each other; said adhesion being tenacious even when the composite film is subjected to contact with water over long periods of time;

2 21. The process which comprises applying a fluid coating composition to de-aeetylated chitin, converting the coating composition into a solid coating, whereby to obtain a composite article in which the coating adheres to the de-acetylated chitin tenaciously even when the composite article is subjected to the action of water for a long period of time.

: 22. A composite article comprising a watercontact with each other.-

ERNEST K. GLABDING. DOROTHY BATEMAN MANEY.