US2078214A - Process of making colored sheets of cellulose esters, synthetic resins, and the like - Google Patents

Description

G. J. ESSELEN ET AL 2,078,214 PROCESS OF MAKING COLORED SHEETS OF CELLULOSE 7 April 20, 1937.

ESTERS. SYNTHETIC RESINS, AND THE LIKE Filed June 17, 1 935 [/2 06/2 tors W Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE PROCESS OF MAKING COLORED SHEETS OF CELLULOSE ESTERS, SYNTHETIC RESINS, AND THE 'LIKE Application June 17,

1 Claim.

The present invention relates to a novel process of making sheets or a web, ofcellulose esters, synthetic resins or like plastic materials in colors or having ornamental effects.

At the present time sheets of cellulose ester plastics or the like can be made by a continuous process which forms a web and seasons it, but it has not been practical to make a wide variety of colors and shades of stock in this way since 10 the process is economical only for large batches which provide long runs .and do not require frequent cleaning of the machines. Only small quantities of any particular color are ordinarily required, but many colors, and shades are neces- 15 sary. Accordingly, colored sheet stock has heretofore been made entirely by the cake or block process, in accordance with which a cake or block is formed, is then sliced into sheets and the seasoning of the sheets completed. This process.

is exceedingly slow and expensive. Our novel process makes it possible to produce colored sheet stock by a continuous process and without resorting to the cake process and at much less expense.

In accordance with the novel process, we make by the continuous process a transparent, translucent or white opaque sheet orweb from cellulose esters, synthetic resins or like plastic materials and thereafter apply simultaneously on both sides of the web a thin coating of a suitable colored or ornamental finishing liquid. When so treated the sheet has the appearance of a sheet made entirely from colored stock. In addition very beautiful effects may be obtained by choosing the colors to be applied to the face or faces of the base material. It will be understood that the base material may be of any desired appearance and the surface coating likewise of any desired appearance, and in general in this specification we have used the word color to include clear transparent, white opaque and even black and have not limited it to the spectrum colors.

The novel process greatly reduces the cost 01' colored sheet stock since the sheet forming machine may be run continuously to form the colorless, i. e. transparent, translucent or white opaque, base material and this material may subsequently be colored or coated or ornamented as desired.

The surface coatings applied may themselves be transparent translucent or. opaque, they may.

be of a single color or a non-uniform mixture of colors, or they may contain ornamental material 55 in suspension, as, for instance, pearl essence.

1935, Serial No. 27,012

metallic scales, and the like and the opposite sides of the sheet may be given the same or different colors or ornamentation. Our invention, therefore, makes it possible to produce by the continuous process many, if not all, of the colored and pearl effects, either plain or mottled which are now produced by the cake process and thus to take advantage of the verygreat economies of the continuous process. Furthermore, certain effects can be produced by our process which are not now possible with the cake process.

The improved process consists in general in preparing a coating liquid from a mixture of a suitable carrier liquid, such as lacquer, and the desired coloring matter; flowing the colored coating liquid onto a bath of suitable liquid, for instance water, to form a film of desired thickness; then lineally passing the sheet to be coated continuously down through the film of coating liquid into the bath at a speed such that the film of coating material on each side of the sheet will be drawn against the sheet continuously; and carrying the sheet through the bath and out of it at a place where the bath is free from the coating film. In practice, it is desirable to employ a tank divided into two parts or cells by a partition which does not extend to the bottom of the tank. In this way the coating is applied simultaneously to both sides of the sheet but is not injured when it is removed from the tank.

In practicing our invention, we prefer to harden somewhat the film on the surface of the bath by removing some of the solvent contained in the coating material just before it contacts with the sheet of base material. When this is done, we treat the surface of the sheet with a small quantity of some suitable solvent or softening agent which activates the surface of the sheet and renders it more easily adherent to the film taken from the surface of the bath. By this treatment, which is not claimed herein as it is made the subject of a companion application, a tougher film is formed and the sheet may be passed through the bath at substantialy greater .speed.

Referringto the'drawing, the figure is a vertical section of a machine illustrating somewhat diagrammatically our invention.

At I is shown a machine having a nozzle H for forming a continuous sheet or web I3. From the die, the web passes through suitable driers It in which the solvent is extracted and the stock is seasoned. The web thus formed is, for instance, of transparent cellulose ester plastic and is to be converted into a blue opaque material. The web I3 is fed lineally by positively driven feed rollers l5 and I6 downward into the bath l1 contained in the tank l8. The tank I8 is provided with a partition I 9 which divides it into two cells. The partition l9 extends downward below the level of the bath I! in the tank, having due regard to variations in level which may take place. Above the entering cell, which is at the left of the partition, we place two troughs 20 and 2| which supply the coating material for the web. These troughs, or other suitable supply mechanism, are arranged to supply the coating material at a uniform regulatable rate. The coating material, which is preferably a suitable nitrocellulose lacquer containing the desired coloring material, floats on the surface of the bath and spreads out forming a film thereon. For.

making light blue opaque stock, this film may be made satisfactorily of a lacquer containing 10 ounces of titanium dioxide, 1 ounce of Chinese blue in each gallon of clear lacquer. The clear lacquer is made by dissolving 1 pound of second nitrocellulose and of a pound of dibutyl phthalate in 1 gallon of solvent mixture. A confactory. At 22 and 23 are shown two air nozzles which blow warm air gently on the surface of the film and remove some of the solvent and harden and toughenthe film slightly as already described. If preferred, the bath may be heated slightly. The web l3 passes lineally down through the film 24 on the surface of the bath and the film adheres to each side of the web. As the web or continuous sheet lineally progresses downward through the bath, the film is drawn by its own toughness and cohesion toward the sheet so that both sides of the sheet are continuously and smoothly coated. At-25 and 26 are shown spray nozzles which apply a fine mist of a suitable solvent, for instance butyl acetate,"to the sides of the sheet after it leaves the feed rolls I5 and I6 and before it comes in contact with the film of coating material on the surface of the bath. After passing through the film, 24 of coating material on the surface of the bath the web passes under the partition l9 and then is led upward through the right hand cell of the bath emerging at 21. There is no film of coating material on this portion of the bath. After emerging from the bath, jets of warm air are directed by nozzles 28 and 29 against the opposite sides of the sheet, drying and hardening the film of coating material sufliciently so that it will not be marred by or adhere to the rollers 30 and 3| over which the material is led. By giving the rollers l5 and .IG and 30 and 3| the same peripheral speeds a festoon is formed passing under the partition and the sheet is guided through the bath without coming in contact with any object from the time it leaves the feed rollers l5 and I6 until it is received by the delivery rollers 30 and 3|.

What we claim is:

The improvement in the continuous process of making sheet stock from cellulose esters, synthetic resins and the like whereby a continuous web of said material is produced which comprises supplying to a bath a floating film of colored liquid capable of adhering to the web, feeding the web lineally through the film into the bath, thereby causing the floating film to adhere to both .sides of the web, thereafter feeding the coated

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