US2186713A

US2186713A - Cupric cellulose impregnated and coated fabric

Info

Publication number: US2186713A
Application number: US125033A
Authority: US
Inventors: Clarence B White
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-02-10
Filing date: 1937-02-10
Publication date: 1940-01-09
Anticipated expiration: 1957-01-09

Description

Patented Jan. 9, 1940 UNITED STATES FATEN'E CUPRIC CELLULOSE IMPREGNATED AND COATED FABRIC Clarence a. White, Moutclair, N. a.

Serial No. 125,033

No Drawing. .Applieation February 1937,

7 Claims.

This invention relates, generally, to cuprammonium coatings, and the invention has reference, more particularly, to a novel fabric emplaying a cuprammonium coating that is so applied to the fabric as to penetrate the same in anchoring relation, whereby the external coating is firmly adhered to the fabric.

Heretofore, coatings of this type have been applied to fabrics in a purely superficial manv ner by passing the fabric to be coated through a cellulose solvent bath of ammoniacal cupric oxide having the general formula of (Cu(NI-I3) 4) (OH) 2,

7 the general effect of which passage through the bath is the solution of a portion of the surface of the passing fabric in the ammoniacal cupric oxide with the formation of an extremely viscous solution of cupric tetrammonium cupric cellu- Io lose of a composition (Cm-I-lmO-lO-Cu) (Cu(NH3)4) which, because of its viscosity, the fact that it dissolves the cellulose with which it comes into contact, and because ordinary grey goods are exceedingly repellant due to the presence of natural waxes, fails to enter the texture of the fabric and remains strictly on its surface, thereby forming merely a superficial coating which is quickly worn off in use. This surface coating is generally coagulated either by heat or by passing through acid baths, whereby the cellulose content is precipitated or coagulated as regenerated cellulose, the ammonia being removed, whereby the remaining surface deposit is caused to assume a very lustrous appearance that is of a greenish blue color due to the copper content, the film or coating in the finished article consisting of regenerated cellulose which, chemically, is C12H20010+Cl1(OH)2, the latter providing the color.

Owing to the thinness of the coating and the necessity of securing sufiicient lustre and density of pigmentation, it is usually necessary to r pass the fabric three or more times through the bath of ammoniacal cupric oxide, drying and heating after each passage. The necessity of these multiple passages adds greatly to the expense of manufacture because of the excessive use of ammonia, the slowing down of production and the additional labor required, while at the same time the strength of. the goods in both warp and filling threads is reduced, because anappreciable portion of the-cellulose thereof is '66 dissolved away from the surface of the fabric.

The three or more passages through the bath also have the effect of causing a serious shrinkage in the width of the goods, which shrinkage frequently amounts to as much as 10% of the original width of the fabric. When cloth as thus 5 prepared is used for filtration purposes, it has been found that the coating, being purely superficial, is readily dissolved in the presence of dilute acids, leaving the coating in a flaccid, porous condition which will not stand up in use. 19 Also, such coated fabrics, as heretofore produced, are objectionable inasmuch as they are subject to mildew in their interiors, where the surface coating does not penetrate.

The principal object of the present invenu tion is to provide a novel cupric cellulose im-' pregnated and coated fabric which is so fabricated as to provide a body of cupric cellulose within the body of the fabric, the function of which body is to anchor and make permanent the exterior or surface coating of cupric cellulose, whereby the novel fabric of this invention has its coating extending practically throughout and integral with the fabric itself and therefore will not flake off or wear off, thereby greatly 35 proionging' the life of thefabric in use, while possessing all the valued properties of the typical superficial cuprammonium coating;

Another object of the present invention lies in the method of making a novel impregnated and coated fabric of the above character, which method comprises depositing within and throughout the fabric body a salt of copper and then insolubilizing such salt in a form which will produce, when brought into contact with a solution 35 of ammonia, the ammoniacal oxide of copper or cuprammonium solution, which latter dissolves some of the internal cellulose and then is regenerated as cupric cellulose within the fabric and on the surface thereof, the surface coating 40 being integral with and bound to the interior impregnation, thereby providing a durable and permanently coated fabric.

Another object of the present invention is to provide a novel method of producing the im- 46 pregnated and coated fabric of this invention, which method lessens the cost of production by eliminating one or more of the usual passages of the fabric through the ammoniacal cupric oxide bath, and at the same time greatly reducing the shrinkage of the fabric, heretofore amounting to about 10% of the width thereof. Still another object of the present invention lies in the provision of a novel impregnated and Qated fabric of the above character'that is II stronger than fabrics heretofore produced, of the same weight, owing to the diminution in the solvent action of the impregnating solution, an increase in-copper pigmentation due to the penetration of the fabric by the cupric cellulose, and a substantial increase in the mildew resistance of the fabric due to the penetration thereof by the surface coating, and a substantial increase in the resistance of the fabric to weathering, and especially to the action of atmospheric acids.

Other objects and advantages will become apparent from the accompanying specification.

In carrying out the invention, the fabric to be impregnated and coated is first thoroughly impregnated by passing the same through a bath of a soluble salt of copper, such as copper acetate, chloride, sulphate, etc., the cloth. being passed between heavy rubber squeeze rollers which force the. copper solution into the fabric. At times it is necessary to repeat this operation in order to secure sufficient impregnation, inasmuch as the fabric contains natural waxes which offer resistanceto the impregnation.

After the fabrichas been thoroughly impregnated, it is dried and passed through a hot bath of sodium hydroxide, which converts the contained copper salts into copper hydroxide. If the impregnation operation is carefully controlled and the fabric is thereafter thoroughly dried before treating with the sodium hydroxide, the cloth will be thoroughly impregnated with the copper hydroxide in an amorphous or 'extremely fine grain crystal form which adheres very firmly to the fibers and will not powder off. This treatment of the fabric with sodium hydroxide also serves to remove the major portion of the natural waxes contained within the fabric, thereby overcoming the normal resistance to impregnation offered by the fabric. The fabric is then washed and preferably dried.

The fabric is now passed through a solution of ammoniacal cupric oxide indicated by the formula Cu(NHs)4(OH)2, there being an excess of ammonia in the solution, whereby a thorough penetration of the fabric is obtained. The penetrating excess ammonia of the ammoniacal cupric oxide solution reacts with the copper hydroxide as follows:

producing ammoniacal cupric oxide solution which reacts with the internal cellulose of the fabric as follows:

Thus cupric tetrammonium cupric cellulose throughout the body of the fabric is produced, this compound being in the form of a gelatinous, viscous coating and impregnation.

The fabric is then passed through rubber rolls or doctor blades which scrape off the excess and also press this compound firmly into the fabric.

the ammoniacal cupric oxide within the fabric being combined with a portion of the cellulose thereof to form cupric tetrammonium cupric cellulose within the bodyof the fabric, and this impregnated material coalesces with the surface material of the same nature, thereby firmly anchoring the cuprammonium surface coating with the impregnated material of the fabric.

The fabric is then passed through a hot flue or overheated cans, thereby driving off the ammonia and producing a fabric with a flexible, glossy "coating that extends throughout the fabric as an impregnation thereof, the reaction which takes place being understood as follows:

As a specific example of the method of this invention,'the strength of the copper salt bath used, 1. e., the acetate of copper, would ordinarily be within the limits of from 6 to 10 ounces of acetate of copper to a gallon of water. The bath may be either cold or hot, but preferably about F., and the impregnation is effected by passing the cloth to be impregnated through this bath, whence it goes between heavy squeeze rolls of rubber, or equivalent, which squeeze out the excess and also force in the liquid of the bath to the interior of the fabric by mechanical pressure. It is sometimes necessary to repeat the passage through the bath and the squeezing through the rolls to achieve an effective impregnation. The goods are then thoroughly dried by passing over cans or through heated flues, or an equivalent drying process. The drying may be effected at any temperature from room temperature to or more, but should be thorough.

The dried fabric is now passed through a solution of sodium hydroxide, the strength being about five to seven ounces of sodium hydroxide to the gallon of water, which strength is increased as the strength of the copper impregnation rises. This solution is used preferably hot. The fabric is passed through the sodium hydroxide bath and between squeeze rolls which remove excess liquid, and then passes to boxes of water where sodium hydroxide liquor is removed by washing. The thoroughly washed fabric is now thoroughly dried by appropriate drying means. The caustic soda treatment insolubilizes the copper as copper hydroxide, and at the same time, by removal of the natural waxes from the fabric, overcomes the natural resistance of the latter to the absorption of liquids, and the fabric is now relatively absorbent.

The dried fabric, now thoroughly impregnated with copper hydroxide in a state of fine division, is passed through a cold (40 degrees, F. or lower) solution of ammoniacal cupric oxide, then squeezed to remove excess of cupric tetrammonium cupric cellulose and force ammonia solution and the cupric tetrammonium cupric cellulose cdagulated and the cellulose thus regenerated, as hereinbefore described.

It will be understood that the invention is not limited solely to the use of acetates of copper,

since any of the salts of copper which are precipi-.

tated as hydroxides by caustic soda may be used. Instead of precipitating a hydroxide by means of caustic, the copper may be precipitated by means of a carbonate of an alkali metal, producing copper basic carbonate, by a chromate of an' alkali metal, producing basic copper chromate, and by sodium sulphide, producing cupric sul-' means w phide, all of which compounds, and some others, are suitable for the production, in combination with ammonia, of a serviceablecellulose solvent terfering with its operation. Such metals are iron, manganese, nickel, cobalt, vanadium, all of which are capable of forming sulphides in the wet way when subjected to the action of alkali metal sulphides. They can be described .as metalsthat are capable of forming sulphides in the wet way. Such additions seem to be inert in most other'respects and exercise no protective.

influence in connection with either coating or fabric.

Also, instead of using copper acetate alone, I may use a rare earth acetate along with the copper acetate, as given in the following example:

Example #2.-The. fabric is impregnated in a bath, the composition of which is as follows: Copper acetate, 6- ounces tothe gallonof water; rare earth acetate,'6 ounces to the gallon of water.

The modusoperandi. of impregnation has already been described.

The impregnated fabric is thoroughly dried. The dried fabric is passed through a hot solution of sodium hydroxide, about 8 ounces to the gallon.

The goods are thoroughly Washed and dried. The fabric, washed and dried, is then passed through a cold solution of ammoniacal cupric houpric oxide, squeeze off. excess cupric tetram-' oxide, and the excess squeezed off .by passage through the rolls.

The coated fabric is now dried under'heat t volatilize and remove all ammoniapresent, leaving a glazed surface colored by contained cupric 'hydro'xide.

monium cupric cellulose, and dry under heat. The passage through the ammoniacal cupric oxide may be repeated, if deemed necessary.

Example #4.--Th fabric is impregnated with the following solution: Copper acetate, 6 ounces to the gallon of water; rare earth acetate, 6

ounces to the gallon of water.

I The impregnated fabric, after drying thorpughly, is passed through a solution of sulphide of sodium, 8 ounces to the gallonof water. The fabric is then thoroughly washed and dried. Pass through the cold solution of ammoniacal cupric oxide, squeeze off excess of cupric tetrammonium cupric cellulose thus formed, and dry under heat. If required, the passage through the ammoniacal cupric oxide may berepeated.

Example #5.-The fabric is impregnated with the following solution: Copper acetate, 6 ounces to the gallon of water.

The impregnated fabric, after thorough drying,

is passed through a solution of sodium chromate.

or bichromate. The fabric is then thoroughly washed and dried. Pass through a cold solution of ammoniacal cupric oxide, squeeze oh the excess of cupric tetrammonium cupric cellulose, and

dry with heat to volatilize the ammonia. The passage through the ammoniacal cupric oxide solution may be repeated, if considered necessary. a

Example #6.The fabric is impregnated-with the following solution: Copper acetate, 6 ounces to the gallon of water.

The impregnated fabric,- after thorough drying,

is passed through a bath of sodium hydroxide. to

It is then washed and dried thoroughly. Pass through a cold solution of ammoniacal cupric o-xlde,. squeeze, and then pass through a dilute solution of acid, e. g., sulphuric acid, after winchwash and dry. The fabric will be coated with a w film of regenerated cellulose, but there will be no copper content in the goods. The internally developed coating will also consist of plain, regenerated cellulose without copper.

The novel fabric of the present invention, thus 4219 produced, has a deep color pigmentation due to the impregnation of the fabric with the coating thereof, the interiorly contained copper compounds adding to the coloring effect of the surface compounds, thereby giving ample depth of 85 shade, which heretofore has been very difficult.

At the same time, the interiorly contained copper compound insures complete mildew resistance and permanency of color in conditions of weather exposure that would quickly remove the copper 80 contained in ordinary cupric cellulose films.

Since ample depth of color is obtained in the present invention without multiple passages through the expensive solution of ammoniacal cupric oxide, not only are considerable labor and, 35

raw material saved, but production is greatly sp'eed'ed up and the shrinkage of the fabric is reduced.

The surface coating has a lustrous, continuous and pleasing appearance that is firm and yet? elastic and well able -to withstand the abra'ding effect of scrapers used in connection with filtration processes, thereby especially adapting the novel fabric of this invention for filtration use.

Although this invention has been described in 6 connection with the impregnation and coating of fabrics, it is to be understood that the same is equally applicable to the impregnation and coating of-yarns, etc.

By therare earth metals mentioned in the 50 above examples, I intend to include zirconium and thorium. V

What .is claimed is:

1. The steps in the method of fabricating an impregnated and coated cellulosic fiber material, 55

comprising thoroughly impregnating the cellulosic fiber material with a soluble copper salt, dry ing theimpregnated material, passing the material through an alkali insolubilizing bath, washing and drying the materiaLand passing the 0 dried material through a solution of ammoniacal cupric oxide.

2. The steps in the method of producing an impregnated and coated cellulose fabric, compris= ing passing the fabric. through a copper salt solu- 5 solution of anunonia'cal cupric oxide and be- 7 tween squeeze rollers to eliminate excess and to I force the solution into the fabrics, whereby cup- .ric tetrammonium cupric cellulose is formed throughout and on the. surfaces of the fabric body.

3. The method of fabricating an impregnated and coated cellulosic fabric, comprising impregnating a fabric with a soluble salt of copper, insolubilizing such salt by passing the impregnated fabric through an alkali insolubilizing bath, impregnating the fabric with ammoniacal oxide of copper to produce cupric tetrammonium cupric cellulose dispersed throughout and covering the surface of the fabric, and then heating the thusly treated fabric to produce the finished impregnated and coated fabric having regenerated cellulose dispersed throughout the body thereof and a surface coating of the same material formed integral therewith.

4. The method of fabricating a cupric cellulose impregnated and coated cellulosic fabric, comprising passing a fabric through a copper salt solution while forcing the solution into the fabric, drying the fabric, passing the dried fabric through a hot bath of sodium hydroxide for converting the impregnated copper salt to copper hydroxide, washing and drying the fabric, passing the fabric through a solution of ammoniacal cupric oxide containing an excess of ammonia to produce cupric tetrammonium cupric cellulose throughout and on the surfaces of the fabric, and

then applying heat to the fabric to drive-off ammonia to produce the finished fabric having a flexible, glossy coating on the surfaces thereof, the material of which coating penetrates throughout the body of the fabric.

5. The method of fabricating an impregnated and coated cellulosic fabric, comprising impregnating a cellulosic fabric with a soluble salt of copper, drying the impregnated fabric, passing the dried fabric through a bath of an alkali compound for converting the copper into a water insoluble form, washing and drying the fabric, passing the dried fabric through a cellulosesol- "vent solution of ammoniacal cupric oxide to form a substantially continuous coating of cupric tetrammonium cupric cellulose, at the same time liberating ammonia, forcing this ammonia into the fabric, whereby this ammonia combines with the copper compound deposited within the material to form ammoniacal cupric oxide. which latter material reacts with the interior cellulose content of the fabric to form cupric tetrammonium cupric cellulose within the fabric, and then heating the thusly treated cellulosic textile fabric to produce the finished impregnated and coated fabric having cupriocellulose dispersed throughout the body thereof and a surface coating of the same material formed integrally therewith.

6. The steps in the method of fabricating an impregnated and coated cellulosic fibrous material possessing a substantially continuous lus-' trons coating of cupric cellulose, comprising ,thoroughly impregnating the cellulosic fibrous material with a soluble copper salt, drying the thus impregnated material, passing the dried material through a bath of an alkali chromate or dichromte capable of converting the copper into an insoluble chromate of copper, washing and drying the material, passing the washed and dried cellulosic impregnated material through a cellulose solvent solution of ammoniacal cupric oxide to form a coating of cupric tetrammonium cupric cellulose on the surface of the material, at the same time liberating ammonia from the solution of ammoniacal cupric oxide, forcing this ammonia together with any excess ammonia present into the interior of the material, where it combines with the copper impregnation and forms ammoniacal cupric oxide, which latter combines with a portion of the cellulose of the material itself and forms cupric tetrammonium cupric cellulose in situ within the fabric, and then heating the thusly treated material to change the cupric tetrammonium cupric cellulose into cupric cellulose, at the same time driving off the ammonia, thereby producing the finished impregnated and coated material having cupric cellulose dispersed throughout the body thereof and a surface coating of the same material formed integrally therewith.

7. The steps in the method of fabricating an impregnated and coated cellulosic fabric possessing a substantially continuous coating of regenerated cellulose, comprising thoroughly impregnating cellulosic fabric with a soluble copper salt, drying the thus impregnated material, passing thedried fabric through an insolubilizing bath of an alkali compound capable of converting the contained copper into a water insoluble form, washing and drying the fabric thus treated, and passing the washed and dried fabric through 'a cellulose solvent solution of ammoniacal cupric oxide to form a coating of cupric tetrammonium cupric cellulose on the surface of the textile material under treatment, at the same time liberating ammonia from the ammoniacal cupric oxide, forcing this liberated ammonia together with any excess ammonia present in the ammoniacal cupric oxide into the internal portions of the fabric, there to react with the contained copper resulting from the impregnation to form ammoniacal cupric oxide solution, which latter combines immediately with a portion of the cellulose of the fabric to form cupric tetrammonium cupric cellulose within the fabric, and passing the thusly processed fabric through a dilute acid solution to dissolve and remove the contained copper, washing the thusly treated fabric thoroughly in water to remove all traces of acids, arid drying to produce a finished impregnated and coated fabric having regenerated cellulose dispersed throughout thereof, and a surface coating of regenerated cellulose united integrally with the dispersed regenerated cellulose within the body of the fabric.

' CLARENCE B. WHITE.