US1857497A

US1857497A - Method of surface finishing paper or fiber board and product of same

Info

Publication number: US1857497A
Application number: US168224A
Authority: US
Inventors: Albert L Clapp
Original assignee: Individual
Current assignee: Individual
Priority date: 1927-02-14
Filing date: 1927-02-14
Publication date: 1932-05-10
Anticipated expiration: 1949-05-10

Description

May 10, 1932. CLAPP 1,857,497

METHOD OF SURFACE FINISHING PAPER .OR FIBER BOARD AND PRODUCT OF SAME Filed Feb. 14. 19 27 Patented May 10, 1932 :umrs s'mrss PATENT OFFICE ALBERT I1. CLAPP, 0F DANVERS, MASSACHUSETTS MErEon or SURFACE rm smne PAPER on FIBER Beam) A m rnonuc'r or SAME Application filed February 14, 1927. Serial No.'168,224.

This invention relates to the surface finishing of paper, and more particularly relatively thick papers such as fiberboard, While in the course of manufacture on modern papermaking machines and has for its object the production of a product having a hig{h finish or glaze and adapted for use as trun board, suitcase-board, or for use in other catained hot, the fuzz pacities where a highly finished product is desired.

In accordance with the method of the present invention, a board is formed on one of the usual types of papermaking machines, passed over driers, and then immediately before or during calendering, an aqueous solution of a glaze-imparting sizing, such as sodium silicate solution, is applied on either or both faces of the board. Such sizing material penetrates rapidly into the surface portion 0 the board, but inasmuch as the board immediately passes into the nip of the calender, there is an insufficient time interval to produce a complete penetration of the solution through the board, and accordingly a crushing or tearing of the board while under heavy pressure in the nip of the rolls is prevented. As the surface-impregnated board passes through the rolls, which are preferably mainon its surface is ironed down and pressed into the silicate, which retains it in such condition and hardens or sets on drying to impart a high finish or glaze to the board.

It is essential that the board being finished by my method be either unsized or filled with material having high aflinity for sodium silicate solution. For instance if it be attempted so to finish a sized board, it is found that the calender rolls are gummed and the board tends to stick to and wind around the rolls, as a sized board so resists the penetration of the silicate solution that a considerable portion of the solution is retained on the rolls. When, on the other hand, the board'is unsized or filled with material having high affinity for silicate solution, the solution penetrates rapidly into its surface portion, so that but little remainson the rolls and accordingly practically no difficulty is encountered dur- The applicability of the present invention may best be understood by reference to a specific example of procedure which is to be described in conjunction with the accompanying drawings, wherein Figure 1 represents in side elevation a portion of the dryers and a stack of calender rolls, certain of which rolls receive the silicate solution from receptacles and apply it to the faces of the board.

Figure 2 represents in plan view the calender stack.

Figure 3 is a section through the two upper calender rolls, on the line 3-3 of Figure 2.

Figure 4 shows an enlarged section through a board surface-finished as herein described.

Referring to the drawings, the board S is passed from the dryer rolls 7 of the machine f under a guide and tension roll 8 to the top of the calender'stack and then successively between each of the pairs of superposed rolls to the bottom of the stack, whereupon, if desired, it may be slit and reeled. As shown, the sizing is applied to the side-s of each of the uppermost calender rolls 9, 9a, from re-' ceptacles 10. The receptacles are constructed and arranged similarly to the water boxes, so called, sometimes employed in water-finishing paper. Each receptacle, as illustrated, is provided with a bottom 10a and ends 105, which conform accurately to the contour of the roll, so that a supply of the sizingmay v be maintained in the receptacle, which may be supported at its ends by brackets 11 secured to the framework 12. While rotating, each of the rolls '9, 9w picksup a film of the sizing and applies it to the surface of the board with which it contacts, the thickness of the film being determined by the clearance between the roll and a doctor 13 extending from end to end across the receptacle 10a near its top. Of course, other methods of applying the sizing to the faces of the board immediately beforeor during calendering may be practised. For instance, the re v cepta'cles 10 maybe arranged to apply the sizing directly to the faces of the board while on the calender rolls. Or suitable coating or spraying devices may be used to apply the sizing to before it reaches the calender rolls or While on the rolls. As the surface-sized board passes through the calender rolls, the fuzz or nap on its surfaces is ironed down and pressed into the sizing, which retains it thus and hardens or sets upon drying to produce a finished and glazed surface a, as shown in Figure 4.

In preparing a strong board suitable for use in the manufacture of trunks and suitcases, for example, the following procedure may be .adopted. Eighty parts of kraft and 20 parts of rag fiber are. charged into the beater engine together with suflicient water to ensure circulation of the fiber. If desired,

other strong fiber, such as manila-or jute, may

be used in lieu of the kraft fiber. The fiber is beaten, say, for six to eight hours, so as to effect sufficient hydration of the fiber to felt properly on the paper machine. The fiber is then diluted to the desired consistency and run off on a paper machine into board of the desired thickness. It is preferable, howcveiythat the board or paper he of greater than 5-point thickness, since if of insufiicient thickness itbecomes enetratedthroughout, rather than only surfiice-penetrated, and is likely to become crushed or torn between the calender rolls. The furnish from which the board is made may of course be varied, depending upon the quality of product which it is desired to realize. For instance, if it is desired to produce a relatively inexpensive board, a furnish composed of, say, 75% ground-Wood or waste papers and 25% sulphite fiber and beaten for about one hour before running off on a paper machine, may be employed. Or, if it is desired to produce a white board, the furnish may be composed of bleached sulphite or rag fiber, either alone or in admixture. In any ofthe furnishes hereinbefore given, 20% to leather scrap may be used in lieu of cellulosie fiber. The leather scrap, when thoroughly beaten out, say for five to six hours, may be advantageous, as it. enhances the felting power of the furnish and apparently increases the wet strength of the board, so that such board while wet on the machine need be'handled with less care. After the board is felted, it is passed over the usual driers, and thence through the, calender rolls. In passing through the calender-s, sodium silicate solutionis applied to its surfaces from the receptacles 10. The solution is preferably about 20 Baum, as this produces adequate penetration into the board, and the desired finish.

' If a very dilute or very concentrated solution were employed, difliculty would be encountered, as a dilute solution would not imart of the desired body and finish to the oard, Whereas a concentrated solution would not penetrate into the board with sutlicient rapidity so that the calender rolls would like- 1y become gummed and the board tend to stick and wind up on the rolls. If desired, pigments such as ochre, lampblack, or the like may be added to the silicate solution to produce a coloring of the surface of the board. Preferably, also, the vcalenders' are maintained hot, say at 160 to 180 F., as a better finish is produced.

#In lieu of silicate solution, aqueous solutions of other glaze-imparting, water-soluble sizes, such as glue,'easein, or starches converted or made soluble by alkali, may be used at the proper consistency, but silicate solution has been found to impart the best finish and at the same time the necessary body to the board.

A board finished as herein described may be varnished or lacquered, or-sin1ilarly surfaced with a small amount of surfacing material, in consequence of the elimination of fuzz or nap, and in consequence of the surface rcsistivityof the board to penetration by va'rnishes or lacquers containing linseed oil or similar organlc soly ent as the liquid vehicle.

A singular advantage of the method of the present invention is that a glaze or finish equivalent or superior to the glaze or finish produced by calendering or supercalendering board formed of fiber and beaten for 12 to 16 hours or longer, is economically produced, for the method is carried out while the board is in the course of its manufacture and Without the use of special machinery.

The method herein described cannot be practised in connection with the method of tub-sizing paper, for if paper were tub-sized larly with modern high-speed paper machincry. When paper is tub-sized, it is customary to dry the paper slowly, as by festooning it or passing it through a drying cham er, as it is of insuflicient strength to pass rapidly over driers. If tub-sized paper were then calendered, the fuzz would not be ironed out to produce a smooth, glazed surface such as herein described, and the hardened size would be crushed under the calender rolls, It is thus necessary, in the practice of the present invention, to apply the sizing to the board immediately before passage into the nip of the calender rolls, so that only surface impregnation occurs, as the board is subjected to heavy pressure before-complete penetration has been effected. Preferably. the first. impregnation occurs after passage through the first nip, as the tension on the paper is considerably reduced and there is hence less likelihood of tearing it.

Where sodium silicate or the other watersoluble sizes mentioned are employed, the finish is not permanent ifthe board is subjected to water or moisture, unless it is varnished, lacquered, or otherwise waterproofed. In accordance with my process, however, I may produce a finish which is waterproof without the necessity of a waterproof coating. This is accomplished by incorporating into the furnish a filler capable of reacting with sonish then formed into board and such board is treated with sodium silicate, the sodium silicate reacts with such filling material to produce a cementitious material which upon drying sets to a hard, waterproofing compound. In accordance with the process described in my application, Serial No. 94,329, filed March 12, 1926, the board is saturated with silicate solution to produce a product which is permeated'throughout with the waterproofing compound. In accordance with the present process, however. the filled board is treated at the calender rolls at its surface portions only, to produce a board impregnated at its surface portion only with the waterproofing compound. If the paper were saturated with silicate solution asdescribed in said application, and then calendered, the board would be crushed or torn. In producing a water-resistant-board according to the present invention, the procedure may be as follows. To the furnish in the beater engine is added 10% to 50% asbestos, or 5% to 20% lime, or a mixture of both asbestos and lime in the desired proportion. The lime is preferably hydrated finishing lime, so called, and is added before or during the initial stages of beating, so as to be uniformly disseminated through the furnish. The asbestos fiber may be used in the form of the relatively short and'inexpensive fiber, such as is commonly used in making asbestos millboard. The asbestos fiber is preferably added after or during the latter stages of beating, so that the length of fiber may be preserved. If desired. the so-called-asbestos floats, or dust, which is inexpensive. may be used in lieu of fiber.

The filled board is treated at the calender stack with sodium silicate, which reacts at its surface portions to produce a cementitious material which functions to retain the fuzz ironed down, and upon drying sets to impart .a glazed and water-resistant surface to the board.

The method of the present invention may be applied expediently in surface finishing multi-ply or liner boards in which the inner plies are formed of fiber sized as usual in the beater, and one or both outer plies are unsized or filled with asbestos, lime or the like, capable of reacting to produce a glazeimparting waterproofing compound. After drying, the multi-ply paper is treated at the calender stack with sodium silicate, which produces the desired finish.

I do not'herein claim the subject matter of my application, Serial No. 89,502, filed February 19, 1926, wherein paper is surfacefinished or glazed while in the course of its manufacture, by treating it at' the calender rolls with an aqueous dispersion of wax, and more particularly a sodiumsilicate dispersion of such waxes. In such case, the waxes effect a surface sizing of the paper, as the sodium silicate solution is so dilute that it has practically no effect. In the present method, a water-soluble, glaze-imparting sizing is employed to effect the surface finishing and surface sizing of the paper.

Having thus described this invention, it is evident that it is capable of change and modification without departing from its spirit or scope as defined by the appended claims. I

What I claim is: I I i 1. A process of treating unsized paper after drying while in the course of its manufacture, which comprises applying an aqueous solution of a glaze-imparting slzmg to the surface of the paper, and immediately calendering the same.

2. A process of treating unsized paper after drying while in the course of its manufacture, which comprises applying an aqueous solution of a glaze-imparting sizing to the surface of the paper, and immediately hot-calendering the same.

3. A process of treating unsized paper after drying while in the course of its manufacture, which comprises applying an aqueous sodium silicate solution of about 20 Baum to the surface of the paper, and immediately calendering the same.

4. A process of treating dry, unsized paper above 5-points thickness, which comprises applying. an aqueous sodium silicate solution to the surface of the paper, and immediately calendering the same.

5. A process of treating dry unsized paper above 5-points thickness, which comprises applying an aqueous sodium silicate solution containing pigments to thesurface of the paper, and immediately calendering the same.

6. A process of treating dry paper filled with lime and asbestos, which comprises surface-treating the paper with an aqueous sodium silicate solution and immediately calendering the same. 4

7 'A process of treating dry paper filled with a material capable of reacting with silicate solution to form a glaze-imparting -waterproofing compound, which comprises surface-treating the paper with an aqueous sodium silicate solution, and immediately calendering the same.

8. A calendered paper sized only at its surface portion with sodium silicate, said paper icate having been applied in the form of an aqueous solution to the surface of the paper immediately before calendering.

9. A calendered paper surface-colored and -surface-sized with sodium silicate, said paper having the characteristics of said sodiumsilicate having been applied in the form of an aqueous solution to the surface of the paper immediately before calendering. p '10. A calendered paper filled with material capable of, reacting with sodium silicate solution to form a waterproofing, glaze imparting compound, and sized only at its surface portion with the reaction product of so-. dium silicate and the material, said paper having the characteristics of said sodium silicate solution having been applied to the surface of the. paper immediately before calendering.

, 11. A calendered paper filled with lime and sized only at its surface portion with the reaction product of sodium silicate solution and lime, said paper having the characteristics of said sodium silicate solution having been applied to the surface of the paper immediately before calendering.

12. A calendered paper filled with lime and asbestos, sized only at its surface portion with the reaction product of sodium silicate solution and with lime and asbestos, said paper having the characteristics of said'sodium silicate solution having been applied to the surface of the paper immediately before calendering.

In testimony whereof I have a'flixed my