US1772968A - Fiber product and method of making same - Google Patents

Description

atented Aug. 12, 1930 DANIEL MANSON surnnnmlvn, .13., or 'rnnn'ron, NEW JERSEY FIBER PRODUCT AND METHOD OF MAKING SAME No Drawing.

molded bodies of varied forms, and is directed both to the products and to the method or process of making the same.

Purposes sought and attained by the invention are: the production of an inexpensive pulp or fiber composition which, when properly formed or shaped and treated, possesses a high degree of density, has low moisture absorption, is tough and durable, capable of being molded or pressed to form, with sharp clean lines, and is well adapted to the production of conduits, panels, corrugated roofing and siding, and fiat products, as well as pressed or molded articles.

For the purpose of clearly differentiating my invention from known prior art I shall composition.

first note briefly such compositions and methods as most nearly approximate those hereinafter set forth, and shall point out the essential differences to which may be attributed the superiority of the latter.

' The early art of making pulp or fiber conduits and products discloses a method which consists in forming a sheet of pulp, with or without a suitable binder or binders, on an 339 ordinary paper-making machine, and winding such sheet, while still wet, upon a mandrel of desired diameter until a tube or conduit of internal diameter corresponding to the diameter of the mandrel, and of desired thickness, is produced. The tube so formed is then dried, and thereafter is immersed in a bath of molten waterproofing material or Such method is slow, and it is difficult to ensure complete saturation of the pulp or fibrous body by or with the waterproofing agent. Moreover, difiiculty is experienced in maintaining the tube or conduit straight and true during the drying operation, and in preventing excessive or uneven deposit of waterproofing material on the inside of the tube or conduit, and consequent irregularity or roughness of surface, likely to make difiicult the drawing of electric wires through the conduit, and to causedamage to the wires or to their insulating covering.

Application filed Jul so, 1926. Serial immense.

Another method of forming conduits'consists in winding the wet paper sheet as it is formed, around a mandrel, drying the same, and compacting it by heat and under pressure of rollers, or in a mold or die. Such method does not, however, solve the vital problem of thorough and complete drying, and the plan of compacting such conduits under heat and pressure does not produce the high density, or ensure the low moisture absorption found practicable under my method.

My method or process is based primarily upon several facts observed in the course of thorough study and experimentation, among which are the following:

1. The binder or binders employed must N be present in the pulp or web in a very finely divided or comminuted state.-

2. Such hinder or binders should have a Luelting point of not less than 250 Fahreneit.

3. The binder should constitute not less than sixty (60) per cent of the pulp mass as it passes to the wire or cylinder on which the sheet or web is formed.

Binders having a melting point of 250 F. or abovev are best comminuted or reduced by grinding in a ball mill, in the presence of a small quantity of water, sufficient to form with the binding agent or mixture, a paste. Under these conditions the grinding is effected without the formation of dust, at small expense, and can be speedily carried to the required point of comminution or division. So reduced or divided, the binder can be 'added to the pulp in the heater, or at any corrugation of the web or sheet when manufacturing a corrugated board, can be performed by standard types of machine designed for such work. A coating of binder of low melting point is applied to the sheet or sheets to further insure adhesion of sucadequate pressure and heat.

cessive windings or successive sheets and to ensure. low moisture abso1 ption, but such ad hesion can be attained only if practically all the moisture be first extracted. The presence of 60 per cent of binder in the pulp mixture together with pressure under heat, will produce a dense and strong web or sheet of low moisture absorption. Sheets or bodies of any desired thickness may be built up by superimposing successive sheets one upon another, coating one of the opposed faces of each pair of sheets with a binder having a melting point below 212 F., and applying I have found in practice that such removal of moisture, compression under heat and pressure, cooling while still under pressure, and coating of at least one of the two opposing faces of the sheet with a binder of relatively low melting point preparatory to final compression, are all necessary to the production of a homogeneous, dense, non-absorbent and durable body comprising a number of layers or laminae.

To compact the sheet, tube, or other body, it is subjected simultaneously to heat and pressure, which together cause a melting of the binder, a forcing of the same into, through, and around individual fibers or groups of fibers, and a thorough and uniform distribuobtainable, and this greater density in turn reduces or precludes absorption of moisture.

Heat and pressure may be simultaneously applied to flat bodies by the use of presses of any suitable type, provided with hollow bed and platen, or hollow molds, capable of being heated by steam and later cooled by water, as is well understood in the art.

Pulp tubes and pipes or conduits can be heated and compacted by being mounted upon one hollow metal cylinder and rolled by a second like cylinder, both of which will be first heated and later cooled while the pressure continues. As rolls have only a line bearing, ample pressure may readily be given to thoroughly compact the pulp tube or pipe, and cooling can be eifected under continuing pressure by closing the steam inlet and opening the water inlet of each metal cylinder. Bodies of other forms may be placed in hollow dies, which in turn may be placed in a hydraulic or other press, heated, caused to press their contents, and cooled under pressure, as in the case of flat bodies.

It is well known to those versed in this art that binders of a bituminous or resinous na-- cles of the pulp mass constituting a single v sheet or web, and a firm and lasting union of the opposing faces of different layers or laminae, if one or both of said faces be coated with a waterproof binder Whose melting point is as low as or lower than 212 F.

Among binders of relatively high melting point, 250 Fahrenheit and upward, suitable to my new process, may be mentioned the following: coal tar pitch, asphalt, gilsonite.

Measurably good results may be secured with a slightly smaller percentage of binder to pulp, or with a binder of slightly lower melting point, than above stated, but I deem it advisable to use at least 60 per cent of binder to 40 per cent of pulp, and to employ a binder having a melting point of 250 F. or higher, permeating each pulp web, sheet or layer. A density of 280 grains per cubic inch and upwards is readily obtainable, and it is desirable that it should not be less than 280 grains.

It is of course understood that the lower melting coating, that is to say, a coating having a melting point below 212 F., is employed only when the coated-body is to be cemented to a similar body under appropriate pressure. Such coating will be applied only when the sheets or laminae are about to be placed in face contact and united, since otherwise they would remain sticky and unsuited to stacking, handling or storage. The outer or exposed surfaces of a finished web, sheet or body will not be coated with the binder or cementing material having a fusion point below 212 F.

What is claimed is 1. A body formed of paper pulp, containing at least 60 per cent of a waterproofing binder having a melting point of at least 250 Fahrenheit, and coated on one exterior face with a waterproof binder of lower melting point, whereby it is adapted to be permanently united to another and similar body.

2. As a new article of manufacture, a body formed of a plurality of dried paper sheets each containing at least 60 per cent of a waterproofing binder having a melting point at least as high as 250 Fahrenheit, superposed one upon another, formed into the desired shape, compacted under heat and pressure, and finally cooled under continuing pressure, to a point below 212 F.

3. As a new article of manufacture, a body formed of a plurality of dried paper sheets each containing at least 60 per cent of a