US2112540A - Art of paper making - Google Patents

Description

March 29, 1938. F. J. M ANDREWS ET AL ,5

ART OF PAPER MAKING Filed Oct. 1, 1937 2 Sheets-Sheet l INVENTOR-S Fran/r M Nc/hdr' w By lesf elr'4afly mm m We ATTORNEYS March 29, 1938. F. J. MOANDREWS ET AL 2,112,540

ART OF PAPER MAKINGv Filed Oct. 1', 1957 2 Sheets-Sheet 2 Patented Mar. 29, 1938 UNITED STATES 2,112,540 ART OF PAPER MAKING Frank J. McAndrews and Lester Long, Philadelphia, Pa., assignors to Charles McDowell, trading as McDowell Paper Mills, Philadelphia, Pa.

Application October 1, 1937, Serial No. 166,860

3 Claims.

This invention relates to the art of papermaking and has particular reference to the manu facture of certain special papers which are known in the art as glassine, "greaseproo and imi- 5 tation parchment papers. Stated more particularly, the invention concerns itself with the incorporation in special papers of the foregoing class during their fabrication of various materials or ingredients to impart to the products desired properties and to render them more suitable for particular purposes.

Papermaking as it has been practiced forrnany years involves the following essential operations:

a. Selection and preparation of the stock;

b.- Formation of a wet web of interlaced fibers.

c. Drying the web.

The stock for making paper consists of vegetable fibers such as wood pulp, rags, old paper or mixtures of these materials depending upon the desired characteristics of the final product. The manner in which the stock is prepared depends upon the character of the stock and also upon the desired characteristics of the final product. Generally speaking, the preparation of the stock involves beating it in the presence of water to d'efiberize the bundles of fibers and to bring the fibers into a state of suspension so that they can readily be felted into a web on the paper machine. In the case of special papers of the class of glassine, greaseproof and imitation parchment papers, the beating is continued until the material becomes very gelatinous, as a result of which the final products are resistant to oil and grease. Glassine paper is also transparent.

In the icilowing specification and appended claims, the term glassine stock is intended to mean a well-beaten or well-hydrated pulp suitable for the manufacture of special papers of the glassine, greaseproof and imitation parchment classes.

The beaten stock or pulp is formed into a wet web of paper on a paper machine. The Fourdrinier, which is a common form of paper machine,

' consists essentially of a. continuously moving wire screening known as the wire to which is imparted a ierlq sidewise movement. A regulated quantity of highly diluted beaten stock is discharged on to one end of the wire from a head box through an inverted weir which is termed a slice. As the suspension of pulp advances on the wire a large portion of the water drains through the wire mesh due to capillary attraction assisted by the revolving table or tube rolls which support the wire. The width of the web is controlled by means of a pair of endless belts known.

as the deckle straps. As the wet web approaches thelimit of travel of the wire, additional amounts of water are forcibly sucked out of the web by means of a series of suction boxes which are in contact with the lower surface of the wire. A tubular roller known as the dandy roll rides on the upper surface of the web in the vicinity of the suction boxes in order to compact the fibers in the web and to improve the formation of the web. As the web reaches the end of the wire it passes over a suction or couch roll which further reduces the water content of the web. By this time the web has become self-supporting and can be stripped of! the wire.

The moist web isstripped OK at the end of the wire and carried through a series of press rolls to squeeze out as much as possible of the remaining water after which it is passed through the driers to remove the residual water. The driers consist of a large number of steamheated rollers, or one very large steam-heated cylinder in the case of a variation of Fourdrinier known as a Yankee machine.

Subsequent to the drying operation, the web may be passed through a. bank of steel rollers or calendars to improve the finish and surface of the paper. In the case of glassine paper, the calendering operation is carried out with heated calender rolls under great pressure, after the dried web of paper has been uniformly dampened or moistened. This supercalendering as it is termed in the art renders the sheet dense, hard and highly transparent.

endered but are not supercalendered. Grease= proof paper and imitation parchment paper difier from each other merely in the degree of machine calendering, greaseproof paper being calendered to less a degree than imitation parchment paper.

Prior to the present invention, it has been the practice to add to the paper stock either in the heaters or at some other time prior to the discharge of the stock on the wire of the paper machine certain materials such as fillers, pigments, coloring matter, waterproofing composi= tions, sizing materials, etc. to impart to the product desired characteristics. This procedure of adding modifying materials is very uneconomical due to the fact that there is a decided tendency on the part of the added material to precipitate in the beater or storage chests and to drain with the separated water through the wire on the paper machine. Hence, only a small proportion of the added material is retained in the Greaseproof and imitation parchment papers are merely machine calweb of paper, and it is necessary to add a much larger amount of material to the paper stock than is desired to be introduced into the paper.

It has been proposed to apply certain of the modifying materials to the paper web after it has been stripped off the wire of the paper machine and after it has passed through some or all of the driers. This proposed practice has the advantage that relatively little of the modifying material is lost during the process, but it has the obvious disadvantage that an additional amount of steam is necessary to evaporate the water which necessarily accompanies the modifying material. Another serious shortcoming is the fact that the modifying material instead of being uniformly distributed throughout the entire thickness or cross-section of the paper web merely coats its surface. The surface coating of modifying material seriously interferes with subsequent operations such as are necessary in the fabrication of glassine paper. This is particularly true in case of waterproofing or water-resisting compositions. As has been stated, in order to make glassine paper the web after it leaves the drying rolls must be uniformly dampened and supercalendered. It is practically impossible to uniformly dampen a sheet of paper which has had applied thereto a coating of waterresistant material in the foregoing manner.

It is the primary object of the present invention .to provide a relatively simple procedure for incorporating in paper during its fabrication various modifying materials or ingredients to impart to the product desired properties and to render it suitable for desired purposes.

It is another object of importance to provide a method of incorporating modifying agents into paper which is readily adaptable to take care of the many different conditions and variable factors which generally obtain in the papermaking process.

Another important object is to provide a methd of incorporating modifying agents into paper which is adapted to be carried out with relatively simple apparatus on the conventional form of Fourdrinier or Yankee paper machine.

Another important object is to provide a meth- 0d of incorporating modifying agents into paper which is particularly well adapted for the manufacture of glassine, greaseproof, imitation parchment and similar papers which possess certain special propertiessuch as transparency or greaseproofness.

Another important object is to provide a relatively simple procedure for improving certain qualities such as strength characteristics, plasticity, transparency and/or water resistance of glassine, greaseproof, imitation parchment and similar papers.

Still another important object is to provide a relatively simple procedure'for materially increasing the water resistance of glassine, greaseproof, imitation parchment and similar papers.

In its broadest aspect, the process phase of the invention consists in applying the modifying materials in the form of a fine spray to the wet web of paper as it is being formed on the wire of a papermaking machine and causing the solution containing the modifying materials to impregnate the entire thickness of the web and the water of the solution to be removed simultaneously Iwith the water normally contained in the wet we In a more specific aspect, the process phase of the invention consists in pouring a quantity of glassine stock on the wire of a paper machine, causing an initial amount of the water to drain through the wire so as to deposit a partially formed non-self-sustaining wet web of paper on the wire, directing a. solution containing the modifying materials in the form of a finely atomized spray against the upper surface of the web in the direction of movement of the web prior to the application of any substantial amount of suction, and removing the water of the solution simultaneously with the water normally contained in the web.

In a still more specific aspect of the process phase of the invention, the modifying materials are compositions which are adapted to improve certain qualities of the final product such as strength characteristics, plasticity, transparency and/or water resistance.

Briefly stated, the apparatus used in carrying out the process of the invention comprises in combination with the wire, slices and suction boxes of a papermaking machine of the Fourdrinier type, means for applying modifying materials in the form of a finely atomized spray against the upper surface of a web of paper being formed and carried along on said wire, said means comprising a series of nozzles mounted independently of said wire and extending the width of the machine between said slices and said suction boxes, said nozzles being directed at an angle to said wire in the direction of movement of the web, whereby the spray of modifying material is applied to the web while it is still non-self-sustaining and prior to the application of any substantial amount of suction thereto.

Additional advantages and aspects of the invention will appear as the description proceeds.

The inventive concept underlying the invention is capable of being embodied in a variety of mechanical forms, one of which for the purpose of illustrating the invention is shown in the accompanying drawings wherein:

Figure 1 is a view in perspective, partly broken away to,reveal otherwise hidden parts, of the spraying apparatus, and

Figure 2 is a perspective view of the wire and associated elements of a conventional form of Fourdrinier or Yankee paper machine in combination with the spraying apparatus of Figure 1, and illustrating suitable connections, etc.

Referring to the drawings in greater detail and more particularly to Figure 1 thereof, the reference numeral l designates a suitable form of spray box. The spray box is illustrated simply as being rectangular in form but other forms and constructions may be employed. The spray box is shown as being supported freely at its ends by the two angle irons 2 and 3. This form of mounting renders it possible to shift the spr'ay box to any desired position on the angle irons for a purpose to be hereinafter pointed out. Stops 4 and 5 may be provided at the ends of angle iron 2 and stops 6 and 1 provided at the ends of angle iron 3 to prevent the accidental displacement of the spray box from the angle irons. The angle iron 2 is shown supported by the two standards or legs vary the height of the standard. Each standard may be fixed at a desired height by means of the pin l4 which passes through registering or alined apertures in the two sections of the standard.

The modifying materials are supplied to the spray box by means of the connection Hi from a suitable source of supply. They may be in the form of dispersions, suspensions and emulsions as well as true solutions. Hence the terms solution and solutions containing modifying materials will be used to include true solutions, dispersions, suspensions and emulsions. The modifying materials and their concentrations depend to a great extent upon the desired characteristics which are to be imparted to the final product. The solution containing the modifying materials is kept at a desired level in the spray box as shown and the overflow is conducted to the mixing tank by means of the connection l5.

As examples of suitable modifying materials which may be used in practicing our invention may be mentioned coloring materials such as dyes and pigments, substances which impart increased plasticity such as 'glycerine, corn syrup, glycols, invert sugars, magnesium chloride, Nulomoline and Krist-O-Kleer, substances which enhance the transparency of glassine such as Cerelose, waterproofing compositions such as waxes, glues, gums, mineral oils, rubber especially in the form of latex, aluminum salts and Tex-Cell as well as mixtures of two or more of any of the foregoing substances. An excellent water-proofing composition may be made by mixing aluminum salts and glue in various proportions. Certain of the waterproofing materials such as glues, gums and rubber in addition to imparting increased water resistance to the final product greatly improve its strength characteristics. Substances such as mineral oils which are in themselves insoluble in water may be readily emulsified and applied in the form of emulsions.

In employing certain of the waterproofing compositions such as for example Tex-Cell and those containing aluminum salts in the manufacture of glassine paper, the concentration should be controlled in order that the composition will not interfere with the dampening of the web prior to the supercalendering. The optimum concentration for a given composition depends to a large extent upon the speed of the machine and the basis weight of the paper being formed. The aforementioned compositions are miscible with water in widely varying proportions and their concentrations can be readily controlled to give optimum results.

The numeral ll designates an air manifold to supply air to all the nozzles, and the numeral i8 designates each of the connecting pipes between the manifold I7 and each of the nozzles which are denoted by it. The nozzles project from a side wall of the spray box through the apertures 20 which are shaped so as to permit the nozzles to be tilted at a desired angle. Each nozzle is provided with an intake or suction pipe M which dips into the solution contained in the spray box and serves to suck up the solution to form the spray. The supply of air from the manifold to each nozzle may be regulated by the individual valves 22. The spray from each nozzle may be regulated by the individual valves 23.

Means are also provided to adjust the angle of all of the nozzles as a unit with respect to the wire. The means consists of a longitudinal rod 24 passing through the spray box and provided with a convenient handle 25 to permit it to be turned or partially rotated. The longitudinal rod is provided with an individual cam 26 for each of the connecting pipes l8. By turning the handle 25 a desired amount the cams 26 are turned a corresponding amount, and this serves to tilt the connecting pipes l8 and their associated nozzles. The aperture through which the air manifold I1 enters the spray box should be 'of suflicient size to permit the manifold to move with the tilting action of the connecting pipes I8.

In Figure 2, we have shown the combination of the spraying apparatus illustrated in Figure 1 with a conventional form of Fourdrinier or Yankee machine. The essential elements of the machine and the direction of the wire are indicated by suitable legends. The spraying apparatus is positioned between the slices and the suction boxes, being shown as being somewhat nearer the slices than the suction boxes. The standards 8, 9, i and l l which support the spray box are secured to the floor independently of the paper machine. The supply pipe i is connected as shown by means of a flexible hose to a supply tank 25A which is preferably supported above the paper machine in any suitable manner. This tank contains the modifying solution which is pumped thereto by means of a pump 26A from the mixing tank fl which may be positioned in a convenient place as the floor below the paper machine. The numeral 28 designates a fresh water supply for the mixing tank. The supply tank 25A may advantageously be provided with an overflow pipe 29 to the mixing tank so that there will be a uniform head pressure on the solution supplied to the spraying device. The overflow from the spraying apparatus returns to the mixing tank 2? by means of the overflow pipe 66 and the flexible connection 3!). Suitable forms of air compressor 38 and motor 32 may be provided to supply the air to the spraying apparatus.

The air connection between the compressor and the air manifold is designated by the numeral 33. *We have found that the best results can be obtained particularly in the case of special papers such as glassine, greaseproof and imitation parchment by the use of relatively low air pressures. However, we are not to be limited to any particuiar pressure as satisfactory results can be obtained at different pressures.

From the foregoing description it is thought to be clear that the horizontal position of the spray box 5 in reference to the slices and the suction boxes can be readily adjusted by simply shifting it on the angle irons 2 and 3. It is also possible to adjust the vertical position of the spray box relative to the wire by adjusting the height of the supporting legs, and it is also possible to adjust the angle of the nozzles relative to the web of paper to be sprayed. Hence, the apparatus has suiiicient flexibility to take care of the many conditions and variable factors which generally obtain in the paper industry. Among such factors may be mentioned slowness or freeness of the stock, temperature, condition and speed of the wire, amount of vacuum on the suc= tion boxes etc.

In actual practice we prefer to position the spraying apparatus in the vicinity of the wire where the stock has lost a sumcient amount of the water to cause the fibers to be partially formed into a web of wet paper. For if the spray is applied before the initial amount of water has drained through the wire, the solution will become a part of the water in which the fibers are suspended and a, considerable portion of the modifying materials will drain through the wire. On the other hand, if the solution is sprayed on the web too near to the suction boxes the impregnation will not be uniform. The exact position of the spraying apparatus in relation to the paper machine will depend upon the variable factors above enumerated.

It is to be particularly noted that due to the fact that the spraying apparatus is mounted independently of the paper machine. the spray issuing from the nozzles is not adversely affected by the shaking of the wire. This is of particular importance in the manufacture of glassine, greaseproof and imitation parchment papers.

It will be readily understood from the foregoing description that by the time the stock which is discharged on the wire at the slices reaches the spraying apparatus an initial amount of water has drained through the wire leaving behind a partially formed non-self-sustaining wet web of paper on the wire. The spraying apparatus applies a finely atomized solution containing the modifying materials to the entire width of the web and the solution is caused to permeate the entire thickness of the web. The water of the solution and the residual water in the paper are removed simultaneously by drainage through the wire, by the suction of the suction boxes and couch roll and by the drying action of the driers, leaving behind the modifying materials uniformly distributed through the web.

In practice it has been found possible by means of the foregoing procedure to impart to papers of the glassine, greaseproof and imitation parchment class desired characteristics such as increased strength, plasticity, transparency and/or water resistance, depending of course upon the particular modifying material incorporated. In the case of waterproofing compositions, papers such as greaseproof and imitation parchment paper which are merely machine calendered have their resistance to water increased to some extent. On the other hand, glassine papers which are dampened and supercalendered have their water resistance increased about 300 to 500%. In each case, the final product retains its resistance to oil and grease which'is characteristic of papers of this class.

The foregoing specification and description include the essential and distinctive thought of our invention, but it is to be distinctly understood that the same may be modified in various ways and/or combined with various other details without affecting the peculiar results obtained and without departing from the spirit of the invention or the scope of the appended claims, in which we intend to claim all the patentable novelty inherent in our invention.

This application is a continuation-in-part of our prior application Serial No. 94,300 filed August 5, 1936.

We claim:

I 1. A method of making glassine, greaseproof or imitation parchment paper containing modifying materials uniformly distributed throughout its entire cross-section, which consists in pouring a quantity of glassine stock on the wire of a paper machine, causing an initial amount of the water to drain through the wire so as to deposit a partially formed non-self-sustaining wet web of paper on the wire, directing a solution containing the modifying materials in the form of a finely atomized spray against the upper surface of the web in the direction of movement of the web prior to the application of any substantial amount of suction thereto. and removing the water of the solution simultaneously with the water normally contained in the web.

2. The method defined in claim 1, said modifying materials being compositions adapted to substantially increase the water resistance of the final product.

3. A method of making glassine paper having a greatly increased resistance to water while retaining its characteristic transparency, hardness, density and resistance to oil and grease, which method consists in pouring a quantity of glassine stock on the wire of a paper machine, causing an initial amount of the water to drain through the wire so as to deposit a partially formed non-self-sustaining wet web of paper on the wire, directing a solution containing waterproofing material in the form of a finely atomized spray against the upper surface of. the web in the direction of movement of the web prior to the application of a substantial amount of suction thereto, removing the water of the solution simultaneously with the water normally contained in the web, uniformly dampening the dried web and subjecting it to a supercalendering operation.

FRANK J. McANDREWS. LESTER LONG.

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