US2296171A

US2296171A - Method of producing sheet material

Info

Publication number: US2296171A
Application number: US304275A
Authority: US
Inventors: Donald G Magill
Original assignee: American Can Co
Current assignee: Primerica Inc
Priority date: 1939-11-13
Filing date: 1939-11-13
Publication date: 1942-09-15
Anticipated expiration: 1959-09-15

Description

Sept. '15, 1942. D. G. MAGILL METHOD OF.PRODUCING SHEET MATERIAL Filed Nov. 13, 1939 INVENTOR Patented Sept. 15, 1942 v 2,296,171 METHOD or raonuomo sass-r MATERIAL Donald G. Maglll, American Can Great Neck, N. Y., asslgnor to ompany, New York, N. Y., a

corporation of New Jersey Application November 1 2 Claims.

The present invention relates to a method of producing sheet or web base material irom which fibre containers and the like-may be made and has particular referen'ce'to such a material of a laminated and moistureproof nature.

An obiect o! the invention is the provision of a method 0! producinga moistureproot laminated sheet or web material wherein a film of microcrystalline or amorphous wax is applied to a preferably thin cellulosic impervious or impermeable web such as "Cellophane" or glassine or to a noncellulosic impervious web suchas Pliofilm" or Korosear' and this web-applied under pressure and at room temperature toa heavier pervious or permeable fibrous base sheet or strip such as chipboard, krait paper, or the like, thereby bond-' ing them together in a manner which extrudes the wax coating on the impervious web into the top fibre oi the pervious base without penetrating through the wax film, thus efiecting a firm adherence and him continuity between the layers to produce a laminated moistureprooi web from which containers or the like may be made.

Another object is the provision of such a method of producing a laminated moistureprooi material wherein the micro-crystalline wax is applied to the impervious web in a molten state and is cooled to'a degree well below its point 01- solidification prior to the impervious web being united with the pervious base strip so that penetration of the wax film by the fibres oi the base stoclc will be prevented when the layers are pressed together.

Another object isthe provision of a method of this character wherein the micro-crystalline wax.

applied to the impervious web is metered in order to produce an accurately reduced minimum film capable oi maximum moisture resistance.

Numerous other objects and advantages of the invention will be apparent as it-is better understood irom the'iollowing description, which, taken in connection with the accompanying drawing, discloses a preferred embodiment thereof.

Referring to the drawing: Figure 1 is alongitudinal vertical sectional view illustrating an apparatus for carrying out the various steps of the instant method invention, the

' view also showing web layers 0! material in place i in the apparatus; and

, Fig. 2 is an enlarged detail used in the apparatus.

In a preferred embodiment of the invention a preferably thin web A oi impervious material, such as glassine, Cellophane," or other treated materials, is coated on one surface 0! a metering rod 3, 1939, Serial No. 304,275

uniform film of micro-crystalline or amorphous wax in a molten state maintained at approximately 180 F. Immediately after its application to theweb the wax coating is cooled to a degree well below its point of solidification, such as for example, to approximately 70 F.

The wax coated impervious web A is then brought' into contact with a preferably heavier pervious fibre base strip B such as chipboard, kraft paper or the like, with the wax film interposed therebetween. While these layers are so aligned they are subjected atroom temperature 1 (approximately 70 F.) to a relatively high pressure of approximately 3500pounds. As shown in p the drawing this pressure is exerted at the nip or the rolls. This pressure unites the impervious web A withthe pervious strip'or web B in a permanent bond and in a manner which extrudes the wax film of the impervious web into the interstices surrounding the top fibres oi the pervious web without the top fibres penetrating through the wax film. This preserves the continuity of the film and thereby insures higher moisture resistance, since the film remains unbroken, and

at the same time results in a firm adherence between the webs. Such a laminated moistureproot material has been found to be ideal for the manufacture oi fibre containers for holding deliquescent granulated or powdered products which may be packed and safeguarded against moisture infecting conditions.

One form of apparatus as disclosed in the drawing for carrying out the steps of this method invention includes a main frame Ii which at one end is formed with brackets l2 carrying a cross rod II on which a roll ll of the impervious web A is mounted. The web A extends over a guide bar it carried in side brackets ll formed on the frame it and thenpasses through a coating device I! which is disposed adjacent the guide bar.

The coating device includes a pair oi upper and lower rollers} i, 22 between which the web passes and which serve as feed rollers ior unreeling the web-from its roll it and for advancing it along its path 01 travel. These rollers are continuously rotated in any suitable manner.

The lower teed roller 22 is also used as an applying roller and rotates in a molten bath of microcystalline or amorphous wax 2'3 retained in a reservoir 24' formed as an integral part 01 the main frame ii. Thus as the roller revolves, it

carries the molten wax up out 01 the reservoirv and applies it to the advancing web. The quan- I on the web surface.

of that actually needed so that this excess may be reduced to a uniform film of predetermined thickness by a metering rod which will be hereinafter explained.

The wax before application to the web is maintained in a molten state-by suitable heating elements disposed under the reservoir. These heating elements are preferably gas burners 26 which are connected into a main supply pipe 21 which leads to a suitable source of gas supply.

The upper feed roller 2| is also used as a pressure roller which presses the web against the I applying roller 22. This pressure roller is maintained in a heated condition to prevent chilling of the newly applied hot wax. This heating effect is brought about by the circulation of steam through the roller and suitable circulation pipes 28 connecting with the interior of the roller are provided for this purpose.

The metering rod hereinbefore mentioned and broadly indicated by the numeral 3|, is disposed adjacent the web exit side of the coating device just explained. This rod includes a preferably round stationary crossbar 32 (Fig. 2) the ends of which are carried in brackets 33 bolted to the sidewalls of the wax reservoir 24. The brackets are formed to hold the bar over the reservoir. Around the crossbar there is wrapped in helical fashion a round wire 34 of predetermined gauge which depends upon the degree of metering necessary, i. e., the thickness of the film desired.

' This wire when viewed in cross section as in Fig.

2 sets off a plurality of ridges 35 having spaces 36 therebetween.

Thus the freshly wax-coated web A as it leaves the coating device, glides over the metering bar 3| in contact with the helically wound wire 34. The wire thus scrapes off all wax except that which passes through the openings 36 between the ridges 35 of the wire and thereby leaves a plurality of small parallel and spaced wax ridges The excess wax falls back into the reservoir. Since the wax is still in a fluid state when this metering is done it immediately fiows or spreads laterally into a film of uniform thickness instead of remaining in the series of parallel ridges as might be expected. This scraping action of the metering rod accurat'ely reduces the wax on the web to a minimum film which is capable of maximum moisture resistance, this being a predetermined factor and obtained in practice by the gauge of the metering wire used in order to provide the proper size of openings 36.

Cooling of the wax film on the web A is preferably effected by air jets, indicated by the numeral 4i and which are projected against the wax covered surface of the web as the latter advances along its path of travel. These air jets issue from a spray head 42 carried on the u per end of an air pipe 43 which extends up through an aperture 44 formed in the main frame H. The air pipe leads to any suitable source of supply of compressed air. A valve 45 in the air pipe is provided to manually control thevolume of the air passing through the jets 4|.

After the cooling operation of the wax coated web A, this web moves forward to meet the base strip B which is now introduced into the path of travel of the coated web. The base strip B is preferably unreeled from a roll 41 which is supported on a cross-rod 48 carried in the main frame II. The base strip passes up and over the lower roller of a pair of pressure rollers 52 and thus comes into contact with the advancing wax coated web A and both web layers, in superimposed position, thereupon pass 7 between the rollers;

The rollers 5|, 52 are mounted on

cross-shafts

53, 54 carried in brackets 55 formed on the main frame ll. These rollers are continuously ro-. tated in any suitable manner. It is these pressure rollers that exert the high pressure at room temperature on the webs passing between and thus unite the web layers in a permanent bond.

The pressure on these rollers may be exerted in any suitable manner.

The single web of moistureproof laminated and bonded material thus produced and indicated by the numeral 51 is advanced toward the discharge end of the apparatus and is wound on a reel or discharged to any suitable place of deposit. This discharge of the web as it is produced is effected by a pairof feed rollers El, 62 between which the web passes. The rollers are mounted on continuously rotating cross-shafts 63, 64 which are carried in side frames 65 formed on the main frame ll.

While the drawing and the foregoing descrip-' tion disclose the production of a two ply web material by joining the impervious web A and the pervious fibre base strip B, it should be understood that more than a single web A or a single strip B could be used and a multiple layer or ply web material could be obtained if more laminations are desired. Furthermore, either the number of layers of either the web A or B may be increased without maintaining the same relationship of a single layer A for a single strip B. This will depend somewhat upon the purpose for which the multiple layer stock will be subsequently utilized.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the process hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A method of producing laminated sheets for the manufacture of moistureproof fibre containers having an inner impervious layer sheet, which method comprises coating a thin impervious carriersheet selected from a class consisting of rubber hydrochloride, regenerated and hydrated cellulose, and vinyl resin, with an adhesive film of molten micro-crystalline wax, cooling said applied film of wax to a degree well below its point of solidification to solidify the same, bringing said wax coated impervious sheet into contact with a heavier permeable fibrous base sheet with the wax coating interposed therebetween, and then uniting said sheets by sub ecting them to high pressure to permanently bond said sheets together by means of said adhesive wax film to produce a laminated moistureproof sheet material for the manufacture of said fibre containers, said pressure being sufllciently high to extrude the solidified wax coating on the impervious sheet into the top fibres of the permeable base sheet, the cooling and solidification of the waxpreventing the. top fibres of'said base sheet from penetrating through the wax film thereby effecting an adherence and continuity of wax film between said sheets to produce a composite laminated moistureproof sheet.

vious carrier sheet selected from a' class consisting of rubber hydrochloride, regenerated and hydrated cellulose, and vinyl resin, with an adhesive film of molten micro crystalline wax, metering said wax coating into a film of predetermined uniform thickness, cooling said applied film of wax to a degree well below itspoint oi solidification to solidify the same, bringing said wax coated impervious sheet into contact v with'a heavier permeable fibrous base sheet with the wax coating interposed therebetween', and

then uniting said sheetsby subjecting them to high pressure to permanently bond said sheets,

together by means of said adhesive wax film to produce a. laminated moistureproof sheet material for the manufacture of said fibre containers, said pressure being sufllciently high to extrude the solidified wax coating on the impervi'ous sheet into the top fibres of the permeable base sheet, thecooling and solidification of the wax preventing the top fibres of said base sheet from penetrating through thevwax film, thereby effecting an adherence and continuity of waxfilm between said sheets to produce a composite laminated moistureproof sheet.

DO NALD G. MAGILL.