US1776790A - Resin-coated pulp board - Google Patents

Description

RESIN COATED PULP BOARD Filed Aug. 4, 1.928

' INVENTORS www 0. HMA/fr mi YS WI. TNE SS Patented Sept. 30,

UNITE-D STATES BECHER, OF HAMILTON TOWNSHIP, MEBCERCOUNTY, NEW JERSEY, ASSIGNOBS TO THE .AGASOTE `MILLBOABD COMPANY, OF EWIN G TOWNSHIP, NEW JERSEY, .L COR- RESIN-COATED PULP BOARD Application tied August 4, 1928. Serial No. 297,534.

Our invention relates to pulp boardcontaining a non-iluxing binder and coated with artificial resin. l y

Pulpboard isusually made by running paper pulp, wood pulp orthe like into a mold and, by means of pressure or otherwise, :emoving the majority of the water, (see, for

` instance, patent to D. M. Sutherland, J r., No.

1,272,566 dated July 16, 1918) and subsequently drying out the remainder of thewater by the application of heat, preferably in a suitably constructed dryer. Thereis usually added to the pulp, prior to sha ing it in the mold, a suitable binder, either a uxlng binder ora non-iiuxing binder. O ur invention relates to a pulp board having added thereto a non-fiuxing'binder, for instance,

a metallic soa Such a non-fiuxing binder is prepared 'from drying oils, such as linseed` described in t e patent to Hubert L. Becher, No.1,67 8,7 20, dated July 31, 1928. e This patent describes the use, as a binder, of a soap oil or China-wood oil, or from rosin, which is precipitated after' the conclusion of the beating operation by the addition of apre-- cipitant, 'such as commercial; sulfate of aluminum, to convert the soap (for instance sodium soap of linseed oil) into an insoluble soap (for instance,'aluminum lnoleate.) In

such application there is described further' more-the use of tannic acid asa dispersing agent for the soap. Instead of tannic acid there may be used a small proportion of a material, for instance red gum ,(the natural resin obtained Vfrom the Xanthorrea tree) which substance, if present in large quantitics, would constitute a ii'uxing binder butin the comparatively small quantity -necessaryV to obtain the ldesired dispersion is negligible PATENT ori-fici:

HAROLD C. VHABTEY., OF `EWING TOWNSHIP, KEMER COUNTY, .AND HUBERT L.

as coacting or bending, or subsequent surfacy ing operations such as sanding) such as has been known in the market for many years.

Upon a completed board ofthis type as a` body layer we place one or more sheets of paper on other suitable fibrous material, im

pregnated with aphenolic or other artificial resin of the class which is transformed under pressure and high heat to 8f` harld insoluble and infuisible condition, for instance, unsized paper impregnated with a -yarnish or other solution of phenolic resin. ,In the preferred more of such sheets (preferably at Aleast three), similarly impre board so as to coat bo h sldes thereof. This aggregate of sheets and board we place between the hollow latens of a press of the v i well known type( o for instance, in patent to Sutherland, o. 1,506,509 dated August 26, 1924) andthen subject such aggregate to suicient heat and pressure to bring the resin in to its final insoluble and infusble condition. Before releasing the pressure we permit the ag egate to cool, forintstance, by flooding t el platens with coldv water so that any moisture which ma be present in the board will not be able to orm. steam as the pressure is released and thus do damage to the board or resin coating. As

the result of theapplication of heat and pressure the resin has not 4only been converted Vinto its final form but-has been caused to form with the sheets an aggregate which in turn has been caused to adhere firmly to the board.

The outermost layer of paper may, prior4 to the application of resin,` be provided-with a suitable design, for instance, wood grainlng,

and this will be visible through the outermost resin layerand add to the artistic eiect of the finished article. :Although in accordance with our invention only one side of the board need be coated in the manner described, we

prefer-to coat both sides thereof so as to prevent a warping of the board which might be caused lby, the entrance of moisture, stresses set up in the resin' layer on one side of the board which would haveno counterated, below the' or by `form of our invention, we place also one or p balancing stresses on .the other side of thev board. Our invention is based upon the discovery that a board of the type hereinabove described4 is sufficiently elastic to act as a cushion to compensate for any unevenness in the surface or surfaces of the platen or platens coming into contact with the resin. .Any unevennessin the surface in contactwith the resin, for instance, a departure of even 1/5000 of'an inch of such surface from a true plane, would cause an unevenness of finish which would render the resultin product unsalable for any use in which t 1e beauty of such product is important.' By our process a satisfactorily uniform gloss may be produced.

It is obvious that the board` must possesselasticity suilicient to eil'ect the objects of our invention and should therefore be thicker, than the surface layer which is to .be applied kn thereto. While we donotknow of any pulp board of the type described which is not sufiiciently elastic to enable a plurality of resinimpregnatedsheets of paper to be applied thereto with a resultant satisfactory gloss, we desire it to be understood that if such a board exists, or may hereafter be discovered,

. of clearness.

in, before compression, and Fig. 2 shows the.

same after compression, the legends applied to the drawings bein self-explanatory and replacing the usual re erence characters. The thickness of the paper sheets shown in the drawing, in proportion to the thickness of the board, is greatly exaggerated for the sake Ewampld 1000 pounds of waste paper are 'beaten in a beater or other suitable mixing engine with from 110 to 130 pounds of a soap prepared from drying oils, such as linseed oil or Chinawood oil, or rosin to which soap has been added from 10 to 20% of its weight'of tannic acid, preferably in the form of a commercial tanning extract. When the beating operation has been completed, the soap is precipitated by the addition for instance 45 to 55 pounds, of commercla sulfate of aluminum. The resultin mixture is run into a mold, for

instance, suc as described in paten't to Suthfi erland,'No. 1,272,566 dated July 16, 1918, from which a large'proportion ofthe water is removed by suction or draining, so Amuch dried board is very compact, although the removal of the water has left 1t just suiiciently spongy or elastic to enable it'to act as a cushion in the manner hereinabove described. To each side of the board are applied three sheets of pa r, each sheet impregnated with a pheno1 own in commerce, in themanner well known ormaldehyde resin of the type well in the art. The aggregate of board and sheets is then vsubjected between suitableplatens to suicient heat and pressure to convert the resin into the iinal insoluble and infusiblc state, such operation at, the same time causing the resin coated papers to form `with the board a firmly united product. Care should l be taken to have the surfaces of the platens as smooth and nearly true planes as possible;

if desired highly polishe -steel or copper plates may be placed between platen and resm.

In order to secure the strongest possible adhesion between'the board and the resin coating, it is advantageous to impregnate the surface or surfaces of the board with a liquid artificial resin, for instance, by dipping the board `into a varnish made o1' such resin and then gently heatin it so as somewhat to set the resin without, owever, bringing it over into the infusible stage. This resin coating will, after the board has been completed, adhere firmly to the board by interlocking with the surface 4libres thereof and will adhere firmly also to the superimposed resin layer,

- thus causing a ver firm adhesion between such resin layer an the board.

,Instead of the paper, we may use any other suitable material in sheet form, such as cloth or felt, capable of absorbing fluid artificial resin. For instance, the outermost sheet may be.constituted by a piece of cloth woven or printed in colored design; we'may also have,

the same design printedl on all the sheets, so that if the outer layer-is worn through or otherwise damaged, the appearance of the next layer may be inl harmony with the remainder of the' outermost layer.

We claim: Y article of manufacture `consisting of a bfv p layer and asuperposed surface layer, thev y layer being of much greater thickness than the' surface layer and consisting of .ahomogeneous pulp board impregnated substantially throughout with a non-Huizing binder, and the surface layer consisting of one or more sheets of brous material embedded in hardened artificial resin and having a uniform finish, said layers being Eermanently secured at their meeting faces y means of such resin.

HAROLD C. HARVEY. HUBERT L. BECHER.

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