US2030156A - Process of coating creped papers and the product thereof - Google Patents

Description

Feb. 11, \N- w ROWE PROCESS OF COATING CREPED PAPERS AND THE PRODUCT THEREOF Filed Jan. 16, 1931 INV Mall aw (its mwaww Patented Feb. 11, 1936 UNITED STATES PROCESS OF COATING CREPED PAPERS AND THE PRODUCT THEREOF William Wallace Rowe, Cincinnati, Ohio, assignor to The Paper Service Company, Lockland, Ohio,

a corporation of Ohio Application January 16, '1931, Serial No. 509,163

, 1'! Claims.

The coating of creped papers with various substances, among which may be set forth as exemplary, bitumens such as asphalt and thermoplastic or other adhesive substances, has involved certain special problems. In the first place, creped paper presenting, as it does, a series of comparatively minute and irregular crinkles, is diflicult to coat evenly with any substance because it is diflicult in the first place to effect a 10 penetration of the coating substances in the irregularities of the sheet so as to obtain a sheet completely coated within and without the crinkles, and in second place because in the main, those operations which are applicable to plain webs of paper or other fabric, are not readily applicable to creped fabrics. Thus if a coating device is employed comprising opposed rollers between which the creped web is fed, the coating substance being applied to one of the rollers, the pressure of the rollers one upon the other, if it is sufiicient to drive the coating substance up into the crinkles, results in a crushing thereof or at least in a folding over of the crinkles. Again, even if a single applicator roll is employed, to which the creped paper is led, there is bound to be some adhesion of the web to the roll requiring some pull to remove it therefrom, which results in the destruction of a considerable portion of the residual stretch in the paper. The paper cannot be doctored without removing further quantities ofthe stretch; and in general with one exception presently to be noted, coated creped papers as compared with uncoated papers have had a relatively small amount of residual stretch. This is extremely important where a considerable amount of stretch is required as, for example, in duplex fabrics where creped paper is joined, say, to burlap, and where a large amount of residual stretch in the paper is highly desirable.

The exception hereinabove noted applies to papers creped in accordance with my process as set forth in Reissue Patent No. 17,633 of April 1, 1930. The process set forth therein comprises the creping of a web, using for the purpose the positive adhesive action of a thermo-plastic substance applied between the paper and the creping roll. This process results, as will be clear, in a creped web which is coated at least upon one side with the thermo-plastic substance used in creping. However, even in the case of creped webs made in accordance with my process, it is sometimes desirable to apply an additional coat of material to the web, and my present process is as applicable to the coating of creped and coated webs made in accordance with my process or otherwise, as it is to the formation of an initial coating upon creped webs which have not been previously coated at all.

The primary object of my invention is the provision of means for coating creped webs, which results in a complete and continuous coating, while enabling me to retain, and in some cases to increase, the residual stretch of the web. Another objeot of my invention is the production of creped webs which are coated subsequently to creping, in which large amounts of stretch are retained. Still another object of my invention has to do with the production of impervious creped webs. Still another object of my invention is the provision of a coating process which 5 can be caused to increase rather than diminish the amount ofresidual stretch in the web.

These and other objects of my invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, I accomplish in that certain process and in those products of which I shall now describe certain exemplary embodiments, it being understood that variations may be made in my process and in the articles made thereunder without departing from the spirit of my invention. Reference is made to the drawing which forms a part of these specifications.

The drawing shows semi-diagrammatically an apparatus suitable for the practice of my process.

In' the practice of my invention I broadly cause a web of paper or other creped fabric to be coated with a coating substance of desired characteristics in contact with a roll; and I remove the paper from the roll by means of a doctor or the like, thereby first forcing the coating substance into the corrugations by the action of the doctor, second removing the paper from the roll by means, of the doctor, so that it is unnecessary to remove from the paper or other web, any residual stretch therein, and third, actually increasing the residual stretch in cases where it is desirable, as will hereinafter be more fully described.

While I may, if desired, give to the web before it is brought into contact with the roll, at least a superficial. covering of the coating substance, and then lead it vto the roll where it is to be treated as described, I have found it more convenient, and I prefer to accomplish the coating by means of the roll itself. Thus I have shown a roll 8. to which I apply either directly or by means of a train of rolls 2, a layer 3 of coating substance from a reservoir 5 thereof. For the sake of an exemplary showing I will take asphalt as a coa ing substance, it being understood that my process as is equally applicable to other coating substances without limitation. Asphalt or bitumens in gen eral involve special problems inasmuch as their plasticity is a function of heat, and can usually be controlled through a range extending between the solid substance on the one hand, and a condition of the substance on the other in which it is quite liquid; By the old coating processes it has been impossible to coat creped webs completely with a bitumen while said bitumen is distinctly plastic as contrasted with liquid, because the very adhesive and viscous character of the mass in itself results in the necessity of stretching the web while removing it from the various instrumentalities which act upon the web. Conversely, however, if the bitumen is heated until it is quite fluid, then frequently undesirable temperatures must be maintained, and there is a distinct tendency for the very liquid bitumen to saturate the web striking through on the opposite side, which is undesirable in many instances. Again, where it is desired to coat a web with successive layers of bitument of different characteristics, the use of high heats and a very fluid condition of the substances will result in an amalgamation thereof upon the web, which in many instances is not desirable.

The creped paper or other web 5 is led against the roll I, as shown, and thereby becomes at least superficially coated with the coating substances. To further increase and control the contact of the web with the roll I, I may provide a pressure roll 6, bringing the web down into positive contact with the coating substance. It is well to let the web follow the roll or drum I for a little distance, whereupon I remove it from the drum by the action of a doctor I. This device not only removes the web but at the same time removes the coating or a portion ofit, thereby deforming the coating and forcing it into the crinkles of the web, In the second place, it serves positively to lift the web from the roll, thereby disengaging it so that it is not necessary to pull the web off the roll and destroy any of its residual stretch. It will be understood that the removal of the paper from the drum I thus becomes a pushing rather than a pulling function.

-The action of the doctor or equivalent device may be controlled as desired. It can be brought up tightly against the drum so as to remove therefrom substantially the entire layer of coating substance thereon, or it may be separated from the drum somewhat so as efiectually to divide the coating, and this in some practices is desirable. The shape of the doctor may further be varied so that the nature of the removal of the paper or other web is correspondingly varied, and the web may be removed with substantially its residual stretch unimpaired, or may even be additionally creped by the doctor so as to be given additional amounts of residual stretch. It is not necessary in my process that the coating be extremely adhesive, or even that it be definitely adhesive at all. The nature of the removal of the web from the roll I is such that the residual stretch is conserved in either case, and the coating is driven into the crinkles. The more adhesive the coating is, the more firmly the web will be bound to the roll, and consequently the more intense will be the action of the doctor in removing it therefrom. The nature of the action can be controlled by a large number of factors, among which those of most importance are the shape of the doctor, the character and consistency of the coating substance, whether determined by temperature or not, and the speed at which the mechanism runs.

Where the coating substance is a thermoplastic substance it may be advisable to control the temperature thereof, and this may be done in a number of ways, such as by applying the substance to the web first and then heating or cooling the web as desired, by controlling the temperature of the roll I and/or the pressure roll 6, or by first applying the coating to the roll I and controlling the temperature thereof so as to bring the coating to the required temperature at the point of application and/ or the point at which the web is removed from the roll.

Thus in my-process the. action of the doctor is not only to drive the coating into the crinkles, but also to act more or less as an ordinary doctor in determining the quantity and nature of the coating applied. Where a web is passed across the ordinary doctor for such purpose, a tensioning of the web at least between the doctor and the take-up device is unavoidable. It will thus be seen that I have provided a means for doctoring the coating upon a creped web which does not result in a tensioning of the web. The amount of my coating can additionally be controlled, however, by other means. Where the coating is first applied to' the web, it may be applied in controlled amounts by any suitable means. Where it is applied to the cylinder I it may be controlled as to amount either by the train of rolls 2 or by the action of a doctor on the roll or otherwise.

Inasmuch as I may actually increase the amount of residual stretch in the coated web by my process, in the coating of creped webs it becomes relatively unimportant how much of the residual stretch is removed prior to the steps I have just described. Thus I may take a creped web and actually remove therefrom a considerable amount of the stretch, intentionally or otherwise, by previous manipulations, and then I may coat it and recrepe by the process just described. In the case of certain characters of crepe it may be even desirable to remove a considerable quantity of the stretch, or even all of the stretch which can be removed by tensioning it in any commercial manner prior to the coating. The re-creping very frequently results in a different and more desirable type of creping, usually finer and more velcompletely coated,-is not entirely impervious. In

such circumstances my process provides a way of securing a completely impervious web in which the coating may or may not be substantially thicker, and in which in certain instances the character of the crepe has been desirably refined. Thus I may take a pre-creped sheet such as a water-creped sheet, or the product of my Patent Reissue No. 17,633; and stretch it as much as may 'be practicable or desirable, and thereafter treat it as I have hereinabove described, controlling the action of my doctor so as to put back into the stretched sheet the desired amount of residual stretch. Where the coating substance is highly adhesive, I may cause the web to follow for a considerable distance the surface of the cylinder I, and either with or without the back-up roll6,

I may tension it between the cylinder I and the 'source of supply of the web,- such as by placing a brake i i upon the shaft of the supply roll l2. Where the coating to be applied is relatively very thin, it becomes of increasing desirability to take out of the original creped sheet a portion of its residual stretch so as to flatten out the crinkles therein; but a pre-creped sheet can be given additional amounts of residual stretch with comparatively much less intense mechanical crumpling action, and a consequently negligible amount of disruption of the coating.

In some instances I will crepe in accordance with the teaching of my'Reissue Patent No. 17,633, or modifications of the process set forth therein, using a relatively thin coat of bitumen, and then after stretching the web more or less as described, I recoat and perhaps partially recrepe the web with an additional layer of bitumen. The second layer of bitumen may be entirely diiferent in its characteristics from the first, and my process is such that, inasmuch as I can control the character of the coating substance as it is being applied, I can control the degree of amalgamation of the several coatings, and thus produce at least a double-coated sheet in which the several coatings retain their individual characteristics.

It is also to be noted that I may employ my process to produce a paper stretchable in more than one direction. I may thus take sheets of paper creped in one direction and reverse the sheets in my coating operation whereby with a proper adjustment of the coating mechanism, I may crepe the paper in a direction other than the direction of the first creping. Again I may take rolls of paper having longitudinal corrugations or the like and crepe them transversely, at the same time coating them. In this operation also some of the residual stretch of the original corrugations or creping may be removed as desired. I may take a roll of creped paper and cut it apart into sheets, turning the sheets through an angle of 90 degrees and pasting or otherwise securing them together. Thus I obtain a roll of paper with the crepes following the direction of the length of the paper. This I may coat and crepe by my process. In

, this way I have found it possible ,to make a paper having stretchability in more than one direction.

Having thus described my invention. what I claim as new and desire to secure by Letters Pateat, is:-

1. A process of coatingcreped paper, comprising bringing creped paper against a roll with a layer of the coating substance interposed therebetween and removing the paper from the roll by a doctor.

2. A process of coating creped webs which comprises bringing the creped web against an applicator with a layer of coating substance interposed therebetween, driving the coating substance into the crinkles of said web, and removing said web from said applicator without tensloning said web by the act of removal.

3. A process of coating creped webs which comprises bringing a creped web into contact with a roll, with a layer of coating substance interposed between said web and said roll, and removing said web from said roll by means which force the coating substance into the residual crinkles of said web, and which liit said web from said roll by a pushing action.

4. A method of coating creped webs which comprises applyinga layer of coatingsubstance to a web and causing said substance to penetrate the crinkles of said web by pushing said web against a doctor.

5. A procesa of coating stretchable paper which comprises stretching said paper to remove a portion of the residual stretch, coating said paper, and after said coating, re-creping said paper.

6. A process of coating stretchable paper which comprises stretching a web to remove a portion of the residual stretch therein, applying a coating substance to said web and forming thereafter crinkles in said web to increase the residual stretch.

7. A process of producing a coated corrugated web which comprises corrugating a web, removing a portion of the residual stretch therein, coating said web as thus treated, and thereafter increasing the residual stretch in said web.

8. A process of producing a creped and coated web which comprises creping a web, removing therefrom a portion of the residual stretch, coating said web and re-creping said web.

9. A process of producing a creped and coated web which comprises creping a web with the interposition of a layer of thermoplastic substance between said web and a creping means, whereby a creped and coated product is formed,

' applying additional coating substance to said web,

bringing said web into contact with a roll, and removing said web from said roll by means of a doctor. I

10. A process of producing a creped and coated web comprising creping a web with the interposition of a thermoplastic adhesive substance between said web and the creping means, whereby an initially coated web is produced. removing from said web a portion of the residual stretch therein, applying a coating substance to said web and re-creping said web.

11. A process of producing a creped and coated web comprising creping a web with the interposition of a thermoplastic adhesive substance between said web and the creping means whereby an initially coated web is produced, removing from said web a portion of the residual stretch coated paper which comprises creping paper first in one direction, turning severed portions of the paper through an angle, bringing the turned paper against a creping roll with a layer of adhesive coating substance interposed therebetween and removing the paper from said roll by a doctor.

13. A process of treating creped paper which comprises bringing the creped paper against a roll with a layer of adhesive substance interposed therebetween, and removing the paper from the roll by a doctor, whereby the character of the original crepe is refined.

14. A process of treating-creped paper which comprises bringing previously creped paper against a roll with a layer of coating substance interposed therebetween,and=removing the paper from the roll by a doctor, whereby to render the layer of coating substance thereon more impervious.

V 15. A process of producing creped paper which comprises creping paper in order to bring about a preliminary breaking down of the structure thereof, stretching said P per and bringing said Duper in substantially flattened condition into a said paper ities.

16. A process of treating paper which comprises creping paper by means of the adhesive action of a thermoplastic adhesive substance whereby to produce preliminarily creped and coated paper, causing said creped and coated paper to adhere to a creping cylinder by means of said thermoplastic adhesive substance, and re-creping said paper by removing it from said cylinder with a doctor.

with finer and more uniform rugosaoao ae 1.7. A process of treating paper which comprises creping paper so as in part at least to break down the structure thereof, removing at least apart of the stretchability of. said paper produced by said creping operation, causing said stretched and broken down paper to adhere in substantial surface continuity to a creping cylinder, and removing said paper from said creping cylinder with a doctor, whereby to re-crepe the same.

WILLIAM WALLACE ROWE.

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