US1641478A - Process of treating paper - Google Patents

Description

Se t. 6 192 p 7 D. FINLEY PROCESS OF TREATING PAPER Filed Sept. 6, 1922 INVENTOR fioz/fk 771W 5 )7 BY W fi A TTORNE YS WITNESS 1 meme Sept. 6,1921.

UNITED STATES 1,641,478 PATENT OFFICE.

nozmn. I'INLEY, OI BERKELEY, CALIFORNIA, A SBIGNOB TO THE 243mm 00!- PANIEB, INC., 01 BAN FBANGISCO, CALIFORN .A CORPORATION 01' nmwm PROCESS OF TREATING PAPER.

Application filed September 6, 1922. Serial No. 588,441.

My invention relates to paper and apropess of incorporating crystalline material m the paper during its manufacture.

An object of the invention is'to provide a process for depositing or incorporating crystalline material in the sheet of-fiber dur' ing the course of its manufacture and preferably, after a portion of the water has been drained from the wet sheet while it is on the wire or carrier felt, at some stage before the sheet has passed thru the press rolls.

Anotherobject of the invention is to provide a paper in which a quantity of crystalline material has been included so that the strength, weight and porosity of the sheet are increased, and qualities imparted which are characteristic of the material used.

My invention possesses other ob ects and features of advantage, some of which, with the foregoing, willbe set forth in the following description of my invention. It is to be understood that I do not limit myself to the showing made by the said description, as I may adopt variant forms of my invention within the scope of the claims.

Referring to the drawings: Fig. 1 is an elevation in diagram of an apparatus with which the process of my invention may be performed. Fig. 2 is a similar view of a modified form of such apparatus. Flg. 3 is an elevation in diagram of a portion of another apparatus with which the process of my invention may be performed in connection with'the manufacture of paper board.

Inthe following specification, I shall use the term aper in a generic sense to include all fi rous sheets in which the process of manufacture comprises the conversion of a mass of fiber suspended in liquid, into a sheet or layer, or a plurality of constituent sheets or layers, from which-the water is afterward expressed by squeezing and drying; and this term includes not only paper in the restricted and specific meaning, but also paper board and felt.

Papers are possessed of. .certain' qualities or characteristicscommon to all. and otherqualities or characteristics peculiar to particular kinds of papers. The most important of these qualities which all papers must possess is strength, and each kind must have a strength requisite to its intended use. Thickness is another important characteristic which must be such as to adapt tbs paper for its purpose. Porosity is a quali of the highest importance in felt, since m of the felt manufactured is saturated with tended use.

Referring to Fig. 1, which illustrates a felt making apparatus, an endless wet or carrier felt belt 2 is arranged in a well known manner upon idler rolls'3, couch roll land between press rolls 6. A screen cylinder 7 is dlsposed below the couch roll, and a drying drum 8 is arranged to receive the wet formed sheet of felt 9 which, first forming on the screen cylinder, is picked up by the carrier felt and passed .thru the press rolls to ex press the excess of fluid.

Arranged above the formed felt sheet preferably just after it leaves the couch roll is a rotatable spindle 12 provided with vanes 13.

A tank 14 is disposed above the spindle and a perforated valve controlled pipe 15 permits solution from the tank to fall in regulatable quantities upon the revolving vanes, wh1ch break up the flow and evenly distribute the solution over the surface-of the sheet in the form of a fine spray, which is in stantly absorbed by theformed sheet as it passes below.

The fluid in the tank 14 is preferably an aqueous solution of sodium chloride containing about 26% by weight of the salt. but for certain purposes which will be made clear later, other water soluble crystalline material may be substituted.

A Between the vanes and the press rolls and below the carrier felt is a suction box 17 for abstracting a portion of the liquid from the formed sheet and the carrier felt. The salt solution discharging from the revolving vanes, tends to work downwardly in the formed sheet, gravitation, the suction box and the press rolls, all helping the salt solution to displace the water present in the sheet as it leaves the couch roll. The suction box will remove the water on the lower side of the sheet and in thecarrier felt,'and as the first water is taken out, the salt solution sinks further into the formed sheet. If a carefully regulated amount of salt solution is t-rate to the "under side of the sheet by the time the press rolls have been passed.

The sheet, after drying on the cylinder 8, is found to be heavily charged with salt, and as an illustration of the results obtained by the application of a salt solution on a fiber sheet in its process of manufacture on a felt making machine the following results are given: Comparisons are made with a similar sheet, untreated, and manufactured under ordinary well known manufacturing conditions; both sheets being of the same weight, thickness, and strength before the treatment of one of them.

Untreated Treated sheet sheet Weight ..grams.. 8. 3 9. 15 Thickness inches. 0351 0384 Strength per square inch by Mullen test ..pounds.. 16. 5 21 From this it is seen that a stronger, heavier and slightly thicker product is obtained. The sheet treated with salt solution was tested for porosity by weighing it and saturating it in an asphaltic compound. It was then compared to a companion sheet from which it differed only in having undergone treatment with the salt solution.

Untreated sheet Treated sheet Grams Per cent Grams Per cent Felt fiber present 17. 48. 17. 7 39. 8 Soluble salts added by treatment.. 5. 1 11. 4 Asphaltlc compound necessary to saturate 18. 5 51.1 21. 7 48. 8

It will thus be seen that in the treated sheet there is not alone a total of 11.4% of the cheaper mineral salt, but in the treated sheet, the ratio of felt fiber to asphaltic compound is 1 to 1.226 whereas in the untreated sample such ratio is 1 to 1.045. The actual percentages of saturation. based on the weights of fiber and asphaltic compound are 122.6 for the treated, and 104.5 for the untreated test sheets, although the apparent saturation of the treated sheet is but 95.3%. The saturated untreated sheet gave a Mullen test of 42.75 pounds, the saturated treated sheet 48.5 pounds.

The results of the above tests clearly de1nonstrate that for a given weight of paper or felt which is to be saturated, my process will permit a smaller quantity of the more valuable fibrous ingredients to be used, the difference being supplied by a corresponding increase in the cheaper soluble salts incorporated. That is to say, my process involves the use of a certain amount of sodium chloride or such other crystalline material of a substances to produce poisonous or unstable compounds. When deposited in the paper from water solution it forms desirably shaped crystals incrusted upon the fibers,

pushing them apart somewhat to produce a greater degree of poroslty, and at the same time interlocking the fibers so that the strength of the sheet is materially increased.

Although I prefer sodium chloride for the reasons named, I may use other materials, such as magnesium sulphate. sodium borate, or disodium hydrogen phosphate. -Mixtures of salts may be used, as for example, a small amount of calcium chloride, or magnesium chloride in conjunction with the sodium chloride. Both calcium and magnesium chloride take up moisture from the air, and by their use, a degree of softnessis imparted to the treatedsheet. I contemplatealso, the use of a salt such as ammonium phosphate or ammonium sulphate to render'the'sheet fire resistant; or a salt such as zincsulphate to impart germicidal properties. and prevent decay both in the sheet itself and the surface on which it lies. In this connection, copper acetate is also good, but the use of copper in any of its forms on a machine composed largely of the ferrous metals is undesirable since the copper is readily ionized if water is present, and in that form, quickly eats away all ferrous parts with which it establishes an electrolytic relation. For this reason zinc sulphate is superior to a copper salt, and it does not react on the paper fiber as does'copper sulphate which liberates free. acid.

While I have so far mentioned only mineral salts, it is possible to use salts of the organic acids combined with mineral bases, or combined with organic bases. or crystalline organic materials other ,than organic salts or esters to accomplish the urposes of my process. For example, one o the sugars may be used.

In Fig. 2, ing the salt in another way. A. box 19 having a 100-mesh screen bottom is arranged above the formed sheet, and provided with well known means for shaking it. A quantity of water soluble crystalline material finely pulverized is placed in the box and as the formed wet sheet passes below the shaking box, the material is evenly sprin- I show an apparatus for applykled upon it and is quickly dissolved by the water in the sheet. By the time the sheet has passed the press rolls, the solution has worked thru it in the manner already made clear.

A type of apparatus for making paper board is illustrated in part in Fig. 3, in which the' component sheets of fiber are formed on cylinders 21 and taken off by the carrier belt 22, which passes over suction box 23 and between small press rolls 24' and large rolls 25. In this case a top felt 27 passes thru the press rolls in contact with the upper surface of the formed sheet. At a convenient-point, the top felt is washed by a spray 28 of fresh water and mechanically Whipped by a whipper 29.

To prevent the top felt absorbing any considerable quantity of salt solution from the formed sheet of board, a relatively light shower of water is sprinkled on the sheet by means 31 which may be similar to the solution spreading means already described.

The effect of this shower of water is to drive down the salt solution previously applied so that the salt solution is capped by a layer of freshwater. The subsequent operations of expressing liquid from the board sheet in an upward direction into the top felt. will proceed only so far as to remove this layer of fresh water. Of course some salt solution will be absorbed into the top felt, but most of this may be, recovered by spraying the upper reach of the top felt with fresh water from a pipe 32 just before the felt passes over a suction box 33. The fresh water will be drawn out by the suction box carrying with it most of the salt solution. This recovered dilute solution may be used in preparing the concentrated solution for the tank 14.

I claim:

1. The process of treating a formed wet sheet of paper which comprises displacing water normally present therein with an aqueous solution of a sodium chloride.

2. The process of treating a formed wet sheet of paper which comprises flowing a solution of crystalline material upon the surface of the wet' sheet, subjecting the opposite surface to a vacuum to displace the water normally present in the sheet with the solution, and evaporating the water to c stallize the material upon the fibers with interlocking effect.

3. The process of treating a formed wet sheet of paper which comprises flowing a solution of sodiumchloride upon the surface of the wet sheet, subjecting the opposite surface to a Vacuum to displace the water normally present in the sheet with the solu tion, and evaporating the water to crystallize the salt upon the fibers with interlocking effect.

4. The process of treating a formed wet sheet of paper which comprises flowing upon the entire surface of the sheet a solution of crystalline material in quantity sufiicient to substantially equal the water normall pres-,

ent in the sheet, subjecting the opposite surface to a vacuum to displace the water normally present in the sheet with the added solution, and evaporating the free liquid from the sheet to incrust the fibers with the crystalline material.

In testimony whereof, I have hereunto set my hand.

DOZIER FINLEY.

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