US3051606A

US3051606A - Rayon fabric reinforced laminated sheet

Info

Publication number: US3051606A
Application number: US776587A
Authority: US
Inventors: Jr Horace P Fry
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1958-11-26
Filing date: 1958-11-26
Publication date: 1962-08-28
Anticipated expiration: 1979-08-28

Description

Aug. 28, 1962 H. P. FRY, JR

- RAYON FABRIC REINFORCED LAMINATED SHEET Filed Nov. 26, 1958 United States Patent 3,651,696 REBNFQRCED LABHNATED SHEET Horace P. Fry, Jr., West Chester, Pa, assignor to American Viscose Corporation, i hiiadelphia, Pa, a corporation of Delaware Filed Nov. 26, 1958, Ser. No. 776,587 2 Claims. ((11. 156-229) RAYON Fannie herent extensibility of the fabric to a value approximating that of the sheet material.

The usual continuous filament viscose rayon yarn, unless highly twisted, has an extensibility of approximately 18% when dry and 22% when wet before its full strength is realized and the yarn breaks. This high extensibility can be considerably reduced, say to about 8% or even less, if during initial manufacture or subsequently, the yarn is subjected to a slashing operation wherein the yarn is wetted and then held under tension While drying. However, the reduced extensibility brought about by slashing is destroyed if the yarn is subsequently gotten Wet and allowed to dry in a relaxed or untensioned condition and consequently slashing is ordinarily only employed when the yarn is to be used in a manner wherein it is protected-from water, as for example, for tire cord.

Open-mesh fabric known as scrim, which may be either Woven or nonwoven, has a wide variety of uses. Obviously, in the case of non-woven scrim, the yarns making up the fabric must be secured together at their crossing points in order to hold the fabric together and this is customarily accomplished by means of an adhesive. It is also customary to employ an adhesive to secure the yarns together at their crossing points in woven scrim, especially in the case of Wide mesh scrim. Because the individual threads or yarns of scrim are not closely packedtogether as they are in a closely woven fabric, the scrim has an extensibility substantially equal to that of individual yarns of which it is formed. Thus, scrim formed of ordinary, unslashed, low-twist viscose rayon yarn has an extensibility of approximately 18% when dry and 22% when wet. Scrim formed of slashed rayon yarns has a much lower extensibility but the adhesive employed must not contain water or be applied as a Water emulsion or suspension unless the individual yarns are maintained under tension until the fabric is completely dry for otherwise the low-extensibility characteristic of the yarn is destroyed, as mentioned above.

.While there are certain volatile adhesives which may be used which do not impair the low-extensibility of the yarn, these create undesirable and expensive Problems in connection with solvent recovery, ventilation, fire hazard, etc. On the other hand, when an aqueous adhesive liquid is employed, the mechanisms necessary to maintain the yarn under tension until dry are complicated and-the fabric-forming operation generally has to proceed at a slower rate. While a'scrim of low extensibility is ideally suited as'a reinforcing lamina for paper or other sheet material, the above-mentioned problems in connection with forming the scrim of a low extensibility rayon yarn have limited its use for this purpose. This use has been further restricted by the necessity for employing volatile, non-aqueous adhesives when laminating the scrim to the paper.

ass sts Patented Aug. 28, 1962 'ice It is an object of the present invention to provide an improved method of laminating an open-mesh rayon fabric to a sheet of paper or like material in such manner that the fabric will have an extensibility substantially equal to that of the materifl to which it is laminated whereby the composite sheet will have a breaking strength substantially equal to the combined breaking strengths of the fabric and the material to which it is laminated.

It is a further object of this invention to provide a method of laminating an open-mesh rayon fabric to a sheet of another material in such manner that the fabric and the sheet to which it is laminated will have substantially the same extensibility and wherein the fabric is formed of ordinary unstrained rayon yarn.

It is a still further object of this invention to permit a highly extensible rayon yarn to be used for forming a fabric which is subsequently used as a reinforcing lamina for sheet material.

Another object of the invention is to provide a laminating technique which permits the use of an aqueous adhesive liquid for reinforcably adhering an open-mesh rayon fabric to a sheet of paper.

Still another object is to provide a method of reinforcing various flexible sheet materials with an openmesh rayon fabric which permits ordinary unstrained yarn to be used to form the fabric to thus effect substantial economy in manufacture.

Other and further objects, features and advantages of the invention will become apparent as the description thereof proceeds.

Referring now to the drawing:

FIGURE 1 is a plan view of a form of apparatus suitable for use in practicing the invention; and

FIGURE 2 is a side elevational View of the apparatus.

In the drawing, the scrim, an open-mesh woven or non-woven fabric, is indicated at 19 and two lengths of sheet material such as paper or the like, between which the scrim is to be laminated, are indicated at 11 and 12. Methods and apparatus for manufacturing scrim are well known in the art and need not be described herein but it is to be noted that in accordance with this invention, it may be formed of ordinary, unstrained, continuous filament, low twist viscose rayon yarn and in fact in order to obtain the full advantage of this invention it is preferably formed of such yarn. However, certain advantages of the present invention may be realized when the scrim is formed of so-called high tenacity yarn, that is to say, yarn which has been dried without allowing it to shrink so as to reduce the extensibility thereof and it is therefore within the purview of the invention to form the scrim of this type of yarn.

As previously noted, the ordinary, unstrained rayon yam has an extensibility of approximately 18% when dry and the scrim formed of such yarn has a like degree of extensibility. In order for the scrim to effectively reinforce the paper or other material with which it is laminated, it is necessary that the extensibility of the scrim and the paper be substantially the same so that when a strain is applied to the laminated "structure the full combined strength of both materials may be realized before either breaks. Now the paper or other material 11 and 12 will normally have very considerably less extensibility than the scrim and according to the present invention the extensibilities of the two materials are equalized by stretching the scrim, wetting it and drying it under tension to reduce the extensibility of the scrim to that of the paper. For example, assuming that the paper is capable of stretching 4% before bursting; the scrim, if it inherently has 18% extensibility will be stretched 14%, wetted and dried Without allowing it to shrink and thereafter so long as it remains dry it will have an extensibility of only 4%. It will be understantially eqpal 'tothat of thepaper. V o p 7 V a A {creped laminated sheet can be made by the process stood that these percentages are used only by way of example and that according to the teaching of this inoriginal size and in doing so will crinkle or crepe the 7 paper in all directions. Because of the creping, the exvention it is necessary to determine the actual inherenttensibility of the paper is greatly increased so that the extensibility of the paper and the scrimare substantially the same. V a A creped laminated sheet may also be made by using a scrim formed from ayarn havingsubstantially the same extensibility ,as that of the sheets with which it is s laminated. In this case the scrim is' not stretched but rollers are driven at a speed sufficiently faster than the speed of the roll from which the scrim is being Withdrawn so that the desired amount of stretch is imparted to the scrim in its longitudinal direction. A'pair of nip plates and 16 are secured to angularly arranged

shafts

17 and 18 respectively, located at one side of the scrim and a similar arrangement of nipplates generally indicated at 19 is mounted at the opposite side of the scrim.

V The opposite edges of the scrim are directed between the respective pairs of nip plates so that as'the'scrim is pulled "forward by the feed rollers l3 and 14 the 'opposite edges thereof are grasped by the nip plates which are rotated ina direction and at a speed totransversely stretch the scrim to the predetermined extent equal. to

the longitudinal stretch. V

The two sheets of paper 11 and 12 are directed between the

feed rollers

13 and 14 so as to be pulled forward thereby but they are fed from their source at the same speed that they are pulled forward so that there is no stretching of the paper.

Spray nozzles

20 and 21 are provided for 'spraying an aqueous adhesive liquid onto 14. The feed rolls extend for at least the width of the j paper sheets so as to hold the scrim in its stretched condition after it is passed beyond the nip plates.

' The water in the adhesive liquid 'rnoistens the scrim? sufi iciently that it willretain its increased size and reduced extensibility if held taut until dry. A series of heated pressure drying rolls 22 are located beyond the feed rollers 13 14 and the sheets of paper and the scrim are held tightly pressedrtogether as they pass around and between the rolls 22 as shown in FIGURE is merely fed through the feed rollers Band 14 between the other sheets. Of course, the scrim itself will originally be of the same width as theother'two sheets. An aqueous adhesive solution isused so that the scrim will have a strong tendency to shrink.- However, the scrim is held taut by the

feed rollers

13 and 14 and the pressure dryer $011522 so that it cannot shrink to an appreciable extent' and its extensibility is therefore substantialiyunchanged. However, unless the paper isespecially sun the scrim will shrink to a small degree and in doing .so will crepe the paper in all directions.

Of 'course, in any of the examples :hereinbefore referred to, the scrim need not be located between two sheets but may be adhered to one or both sides of a single sheetof paper or the like.

Having thus described several methods embodying the inventive concept, what is claimed is: I

l. The method of making a rayon fabric reinforced laminated paper, comprising stretching an open-mesh fabric formed of unstrained rayon yarn having a substantial degree of extensibility to the extent that the individual yarns of the fabric are elongated to the point where their remaining extensibility is approximately equal to the extensibility'of the paper with which the fabric is to be laminated, applyingan aqueous adhesive to one face of each of twosheets of paper, introducing the fabric while in the above mentioned stretched condition between the adhesive coated faces of the sheetsof paper whereby the fabric is wetted by the aqueous adhesive, and drying the adhesive and the fabric while maintaining the fabric in the stretched condition whereby the individual rayon yarns retain their elongation so long as :they remain dry to thus produce --a rayon fabric reinforced paper wherein the fabric and'the paper have approximately the same extensibility.

2. Afterleaving the rolls 22 the now laminated. sheet V 23 may be wound into a roll. The laminated sheet 23 fthus'comprises twosheets of paper or the like inherent- V lyhaving a reasonably' low extensibility between which i is :adhered the scrim which now has anextensibility subof this invention-and this is most advantageouslyaccomfplished by using a scrim made-from slashed hava transversely. to an extent where its remaining extensi V bility 'isv snbstantially equal tothatof the paper or the like, but instead of using an aqueous adhesiveliquid a 'nated is especially strong, the scrim will return to its non-aqueous adhesive such as asphalt may be employed.

As the scrim. and the paper passaround'and between the rollers22, the a'sphalt causes the scrim to adhere to: the paper but sincegno water is appliedto the scrim jit will xhavela strong ftendency'to return to "its original dimen- I sions after passing through the rolls 22"and un1ess the .paper or other material between which the scrim is lami V 2. The method of making a rayon'fabric reinforced laminated paper, comprising stretching an open-mesh fabric formed of unstrained rayon yarn having a substantial degree 'of extensibility tothe. extent that the individual yarns of the fabric are elongated to the point where their remaining extensibility: is approximately equal to the extensibility of the paper with which the fabric is ;to be laminated, applying an'aqueous adhesive to one faceof each of twjo sheets of paper, introducing the fabric while in the above mentioned. stretched conditionbetween the adhesive coated faces of thejsh eets of paper whereby the fabric is 'wetted' by the-aqueous adhesive 'and applying heat and pressure to'the outer faces of the sheets of paper to dry the adhesive and the fabric and maintain the fabric in the stretched condition during the drying whereby the individual rayon yarns of the fabric retain their elongation to thus produce a rayon fabric reinforcedpaper wherein the fabric and the'paper have approximately the same extensibility.

References Citefd inthe file of this patent V UNITED STATES rAT N'rs 2,503,024 Boese et al. V Apr. .4, 195.0 2,575,666 Knudson ,V. V Nov. 20, 1951 2,674,555 Pahl etal. ';.i Apr. 6, 1954 i OR I P NT 438,786 a Great Britain Nov. 21, 1935 Australia ..V Oct; 29, 1952

Claims

1. THE METHOD OF MAKING A RAYON FABIC REAINFORCED LAMINATED PAPER, COMPRISING STRAETCHING AN OPEN-MESH FABIC FORMED OF UNSRAINED RAYON YARN HAVING A SUBSTANTIALLY DEGREE OF EXTENSIBILITY TO THE EXTEN THAT THE INDIVIDUAL YARNS OF THE FABRIC ARE ELONGATED TO THE POINT WHERE THEIR REMAINING EXTENSILILITY IS APPROXIMATELY EQUAL TO THE EXTENSIBILITY OF THE PAPER WITH WHICH THE FABRIC IS TO BE LAMINATED, APPLYING AN AQUEOUS ADHESIVE TO ONE FACE OF EACH OF TWO SHEETS OF PAPER, INTRODUCING THE FABRIC WHILE IN THE ABOVE MENTIONED STRETCHED CONDITION BETWEEN THE ADHESIVE COATED FACES OF THE SHEETS OF PAPER WHEREBY THE FABRIC IS WETTING BY THE AQUEOUS ADHESIVE, AND DRYING THE ADHESIVE AND THE FABRIC WILE MAINTAINING THE FABRIC IN THE STRETCHED CONDITION WHEREBY THE INDIVIDUAL RAYON YARNS RETAIN THEIR ALONGATION SO LONG AS THEY REMAIN DRY TO THUS PRODUCE A RAYON FABRIC REINFORCED PAPER WHEREIN THE FABRIC AND THE PAPER HAVE APPROXIMATELY THE SAME EXTENSIBILITY.