US2146871A - Method of making decorative fiberboard - Google Patents

Description

Feb. 14, 1939.

J. A. WIENER ET AL Filed AOM.. 3, 1935- INVENTORS. JOHN A w/ENE BRANK A. BRO/m.

1 n J :i

Patented Feb. 14, 1939 IUNITED STATES M'ETHOD OF MAKING DECORATIVE FIBER- BOARD y John A. Wiener,swego, and Frank A. Bromley,

New Rochelle, N. Y., assignors to Johns-Manville Corporation, New York, N. Y., a corporation of New York Application October 3, 1935, Serial No. 43,336

3 Claims.

This invention relates to a decorative fiber board having irregularities of surface.

The invention, in one embodiment, relates also to the method of making such a product by a method including forming a board containing cellulosic fibers and a sizing composition and pressing thereagainst a member of irregular surface, at an elevated temperature, adapted to cause drying of the board simultaneously with the shaping of the surface thereof and to control the color of parts of the board in direct contact with the material of the said member.

Other objects and advantages of the invention will appear from the detailed description that follows.

An embodiment of the invention that is preferred at this time is illustrated in the attached drawing.

Fig. 1 is a plan view of a liber board of irregular surface made in accordance with the invention. l Fig. 2 is a plan view of a pressing member adapted to produce irregularities, of kind desired, in the face of a ber board during the drying thereof.

Fig. 3 is a diagrammatic edge view of the assembly of fiber board and pressing equipment.

' There are shown elevations I and depressions 2 in the face portion of the ilber board 3.

The pressing member has continuous parts 4 and apertures 5 adapted to produce in the -face portion of the fiber board the desired surface irregularities, as, for example, the said elevations and depressions.

At 'the time lthe impressions are made, kthe pressing member (embossing element) 6 is disposed on one face of the fiber board, suitably the supplied in any convenient mannen-as by electrical heating of lone or both of the' rigid .members 8, and. is thus imparted to the member 6, and,

j also, tothe member l, if used,`as well as to the board 3 thatvis being impressed..l 'I'he members B-and v"I, asV well as the plates 8, may be constructed of iron or steel or the like.

The method pf making the improved article is illustrated by the following specic example.

There is first provided a supply oi' suitable cellulosic iibers. Thus, there may be provided mechanical fibers, such as a mixture of shredded spruce log and ground wood screenings representing the oversize material screened out of news print stock. w

To a suspension in water of the selected iibers there is added an ingredient or sizing composition adapting the-board, made as described below, to undergo discoloration under the conditions of heating to which certain portions of the board may be subjected during manufacture. Thus, there may be added a small amount of a material selected from the group consisting of commercial aluminum sulphate, this term including alumi num sulphate or the alums containing, in the usual commercial forms, a trace at least of free sulphuric acid or being adapted to develop such a trace, montan wax, emulsiiiedparain wax, and a resinous material such as. a commercial, inexpensive grade of rosin commonly known as paper maker's rosin or "dry rosin size. suitably, there is used aluminum sulphate and a mixture of montan wax and rosin, emulsiiled by warming and Parts by weight,

approximate, Added ingredients 100 arts of ber' on t e dry basis Paper makers alum (aluminum sulphate)-.--- i 0. 5 Paper makers rosln 04 5 Montan wax gli) Caustic soda (impure sodium hydroxide) The amount of caustic soda or like alkali used should be adequate to neutralize the acidity of the wax and resin and emulsify them, but inade quate to exert injurious eifect on the bers.

The mixture of fibers and size, suspended in a large amount of water, say, 97 parts by weight to 3 parts of' fibers, is supplied to a filtering mold box, press bed having a filtering bottom, or other suitable sheet forming machine allowing escape of water. With the moldtype of sheet forming machine, most of the water escapes by natural filtration, under the influence of gravity, through the iiltering bottom of the mold. Pressure is then applied by means of a die-plate, suitably under hydraulic pressure, to force out as much as possible of the remaining water and consolidate the bers into a wet board or sheet oi thickness desired at this stage.

The degree of consolidation eected may be greater than is usual in making conventional ber insulating board. Thus, if the bers'aresuch that the nished ber board made therefrom in usual manner weighs 12 ounces per square foot,

1/2 inch thick, the board made from the similar fibers for the present purposes may well have a density that is greater, say, by 15 to 35 per cent.

The consolidation is made suitably at a pressure of the order of 140 pounds per square inch and the Wet board should be about inch thick, if the nished dried board is to have an average thickness of about 1A inch.

The wet board is next subjected to the treatment to form the desired irregularities of surface.

In this step the board is placed between rigid plates in a suitable press and a pressing member, having a discontinuous. surface pattern such as the apertured surface shown in Fig. '2, adapted f to provide surface irregularities of the kind desired in the nished board, is disposed in contact with and pressed strongly against one or each face of the wet board (Fig. 3).

Simultaneously with the pressing operation, heat is supplied to the pressing member and is conducted thereby to the portions of the face of the ber board. If discoloration is desired, the member is maintained, for example, at 212 F. to 300 F. At such a temperature, the member is adapted to cause discoloration of the ber board composition in contact therewith.

There has been used to advantage apertured pressing members, so that certain portions of the face of the ber board are in contact with the material of the pressing member and other portions of the face of the ber board register with the apertures extending through the said member. The thickness of the pressing member and, consequently, the depth of the apertures therein is greater than the difference i`n elevation between the high and low portions of the nished board. Therefore, the portions of the board that areelevated during vthe pressing, with respect to intervening portions, extend into but not completely through the apertures and in contact with the heated plates 8. The result is that the elevated and depressed portions of the board are subjected to different maximum temperatures. A pressing member that has been used to advantage has an overall thickness of 1A; inch.

During the impressing and heating, the depressed portions undergo permanent supercial discoloration, with the result that the shadow effect, noted on looking at the finished board, is greatly increased by the contrast of the darkened depressed portionswith the lighter elevated portions.

Simultaneously with the impressing operation providing the irregularities of surface, the board is dried at the temperature to which' it is subjected. The simultaneous impressing and 'drying sets the impression in substantially permanent form.

After the drying and impressing are completed, for instance, after 50 to 60 minutes exposure to the elevated temperature, the plates 8 are separated and the nished board is withdrawn from the assembly shown in Fig. 3.v It is then sawed or trimmed to desired dimensions and is ready for use as a decorative ber board. Inthe preferred embodiment, it is of particular merit for use as decorative thermal insulation.

Various designs may thus be imparted to ber board, by proper selection of the kind of apertures or type of pressing member. Also, the extent of the darkening of certain portions of the sheet during the impressing may be varied, by change vof composition of the board. f

We have found, however, that a very important factor in the control of color of the surface of the nished board is the temperature at which the pressing member is maintained while in contact with the said face. Curiously enough, there is more discoloration of the ber board during the step of impressing when the impressing member is at a lower temperature, within limits. Thus, to give depressions of darkened surface in the nished dried board, we maintain the impressing member at a temperature below 300 F.

and at aI temperature sulciently high to cause evaporation of water rather rapidly from the wet board, as at a temperature of 250 F. On the other hand, to preserve approximately the original color of the ber board in both the depressed and elevated portions, we maintain the impressing member at a temperature of the order of 350 F., say, at a temperature within the range of 325 to 380 F.

It will be understood that the details given are for the purpose of illustration, not restriction, and thatyariations within the spirit of the invention are intended to be included in the scope of the appended claims.

What we claim is:

1. In making a ber board of irregular surface. the method which comprises forming a ber board including felted cellulosic bers, water, and a sizing composition including a trace at least of sulphuric acid adapted to cause discoloration at an elevated temperature, pressing against a face of the board a member provided with surface irregularities adapted to form in the board irregularities of surface of kind desired, and maintaining the member at an elevated temperature such as to cause discoloration of the board in portions of the said face directly in contact with the material of the said member.

2. In making a ber board of irregular surface, the method which comprises forming a ber board including felted cellulosic bers, water, and a sizing composition including a commercial aluminum sulphate, rosin, montan wax, and caustic soda in amount adequate to neutralize the acidity of the rosin and montan wax, pressing against a face of the board a member provided with surface irregularities adapted to form in the board irregularities of surface of kind desired, and maintaining the member at an elevated temperature such as to cause discoloration of the board in portions of the said face directly in contact with the material of the said member.

3. The method of making a ber board of ir-. regular surface which comprises forming a ber board including felted cellulosic bers, water, and a material selected from the group consisting of aluminum sulphate and the alums; pressing against a face of the board an embossing elef ment of discontinuous surface pattern, adapted 'to form in the board irregularities of surface of kind desired; and maintaining the embossing element, during the pressing operation, at an `ele vated temperature such as to cause discoloration of the board in portions of the said face directly in contact with the material of the said element.

JOHN A. WIENER. FRANK A. BROMLEY.

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