US1789825A - Hard grainless fiber product and process of manufacture - Google Patents

Description

Jan. 20, 1931. w. H. MASON 1,789,825

HARD GRINLESS FIBER PRODUCT AND PROCESS OF MANUFAGTURE Filed June 13, 192s fiil- ATTORN EY 5 Patented Jan. 20, 1931 UNITED STATES PATENT OFFICE WILLIAM n. MASON, or LAUnEL4,/M1ss1ss,iAssIGNoa 'ro mAsONrrE coBronArIoN, or LAUREL, MISSISSIPPI. A CORPORATION or DELAwarutl HARD GBLILESS FIBER PRODUCT lANI) PRCESSOFWMAN'UFAGTUR'E Application led June 13,

My invention relates to the production of Yfiber products suitable for use-as artificial lumber and characterized by a high density and great rigidity and strength, together with resistance to penetration by water or 5 water vapor and freedom from deterioration by action of the elements when used as building material or for like purposes.

The use of corrugated iron for the roofing and siding of buildings is well known, such materia-l being made in various weights or thicknesses to adapt it to dii'erent uses, and galvanizing is usually resorted to in order to obtain a material having a fair degree of resistance to deterioration. Corrugated iron sheetswhen used for roofing are ordinarily laid upon horizontal purlins which are spaced apart at distances of 3, 4 or 5 feet, and the iron sheet must be capable of sustaining a load between such points of support of about to 60 pounds per sq. ft.

Obviously the corrugations greatly increase the stiffness of the sheet and in practice a certain form of corrugation has become standard for most purposes, viz., a distance of 2% inches from crest to crest and a depth of 1/2`inch from top of crest to bottom of groove. Such sheets when formed of iron of 16 to 28 gauge thickness are well adapted to o sustain ordinary roof loads. Another advantage of the use of corrugated sheets is that the holes through which the nails or other securing means extend may be at the crests of the corrugations, whereby leakage of water therethrough is avoided, and the sheets may be laid in'overlapping relation as regards their side edges sothat the lapped portion presents an upwardly convex surface I well adapted to prevent leakage'. Corrugated sheets have the additional advantage that the corrugations by slight changes of curvature permit expansion and contraction of the sheet which, may be caused by changes of temperature.

Corrugated iron roofing, however, even when galvanized, is 'subject to fairly rapid deterioration, especially when subjected to adverse Weather conditions. The nail holes and spots formed by abrasion or otherwise enlarged by corrosion and the sheet unless ...8. 1 ...,...HHSSUED protected by frequent applications of paint or other protective coating eventually loses its strength and substance. Furthermore, metal sheets have little or no heat insulating property and consequently a building having walls or roof or both ot' such material is wasteful of`heat in winter and uncomfortably hot vin summer.

The objections inherent in the use of sheet metalas pointed out may be avoided by substituting therefor a non-metallic substance, provided the same can be manufactured with suiicient 'cheapness into corrugated sheets havingsuiicient strength and rigidity, resistance to water penetration and corrosion, and freedom from deterioration to enable them to be successfully used.

Vegetable fiber felted and pressed into sheets has the advantage of cheapness, but

heretofore has not been lproduced in co1 rugated sheets having suiiicient strength, rigidity and resistance to weather to enable them to be used as a building material substitute for corrugated iron.l

The present invention has for its object the production of a vegetable fiber sheet having the necessary qualities to adapt it for use as a substitute for sheet metal for many purposes.

Reference is hereby made to the accompanying drawing, of which:

Fig. l is an end elevation of a portion of -a single wet lap sheet from which a corrugated sheet may be produced in accordance with my invention. Fig. 2 is a similar view of the finished corrugated sheet.

Fig. 3 is a similar view of two superposed sheets of wet lap.

Fig. 4 is a simllar view of a corrugated sheet formed therefrom, and

Fig. 5 is a similar view of a flat sheet formed from the wet lap sheets of Fig. 3.

In order that a iber sheet with sufficient strength to enable it to sustain a load of 30 to (iO-pounds per sq. ft. between purlins separated by 3 foot to 5 foot spacing, may be produced at a cost sutiiciently low to enable it to be used as building material, several things should be taken advantage of. -Firstz T he raw material should be obtainable in large quantities at a low price. This qualification is met by the use of Wood chips produced from the Waste Wood of saw mills, or low grade wood, the quality of which is not sufiiciently good to enable it to be used for lumber. Second: The raw material should be convertible into fiber pulp at low cost and With minimum loss of material. A suitable process having the advantages mentioned is disclosed in U. S. Letters Patent No. 1,578,609, granted to me on March 30, 1926, `in` accordance with which the fibisbtained by subjecting the Wood chips in a closed high pressure chamber to penetration by a fluid Vsuch as steam at high pressure, and progressively discharging the same through a constricted outlet from said chamber, whereby the sudden expansion of the lisultilized for disintegrating rtlgiinatenrl. Third: The fiber pulpfsobtined should preferably be .siZredat low cost, so that board produced therefrom will have the size distributed substantially uniformly throughout and will be highly resistant to water and moisture. A suitable process for carrying out this step is disclosed and broadly claimed in my copending application Serial No. 277,382, filed May l2, 1928, and consists briefly in subjecting the fiber to agitation in a Water bath with melted petrolatum, paraflin or equivalent hydrocarbon at a temperature sufficiently hi h to revent congealing of the hydrocar on. or example, in order to produce a sheet suitable for use as a substitute for ordinary corrugated iron, l may use the following proportions of paraffin or petrolatum, each melting at about 125 F., to 100 parts of liber (dry Weight), viz., parain 1% per cent. to 2% per cent. or petrolatum 2 per cent. to 31/2 per cent. In either case the temperature of the water bath may be at or above 130 F. Petrolatum is not as efficient per unit Weight as paraffin in its waterproofing quality, but its cheapness more than compensates for the increased quantity which should be used. The pulp may be felted in any suitable apparatus, for example a machine of the FourdrinierA type by which a Wet felted sheet, or Wet lap is formed. Fourth: In forming the Wet lap sheet, it is important and highly desirable in order to obtain a product of maximum strength to resist flexure, that the fibers be Well interlocked with each other in every direction. I have obtained such results by causing the pulp to be violently agitated just before it reaches the travelling screen of the F ourdrinier machine, so that at the very beginning of the formation of the sheet the bers are in a very loose and Widely separated condition. They settle with great rapidity and quickly build up on the screen a sheet several inches thick which may be reduced by loss of free Water in the machine to a wet lap sheet a having a thickness of about 1% inches, as shown in Fig. 1, for the production of a corrugated sheet b having a thickness of M3 inch, as in Fig. 2. Sheets of greater thickness may be produced by proportionately increasing the fiber content of the Wet lap but With a more than pro ortionate content of Water, as Will be descri ed.

The Wet lapsheet having been thus formed is conveyed to a press in which it is subjected to high pressure, for example, from 200 pounds to 700 pounds per sq. in., between ieated platens as disclosed in my aforesaid application Serial No. 277,382, filed May l2, 1928, and in U. S. Letters Patent No. 1,663,- 505, granted March 20, 1928, care being taken that the full pressure be applied to the wet lap sheet before the temperature of any part Water vaporizes, viz., 212o F. at atmospheric pressure, and that full pressure be maintained until the sheet is dry. The temperature of the platens may be from 275o F. to 500O F., although somewhat higher or lower temperatures may be employed if desired. A Wire screen should be inserted between one or both of the platens and the felted sheet to permit escape of moisture during the drying operation, and to cause the finished sheet to be formed with a. rough surface on one or both sides. This screen member should be of slightly greater Width and length than the Wet lap sheet to insure maintenance of an outlet for the moisture. It should be formed with corrugations to fit the platents and may be supported in any suitable manner.

A The platens have pressing surfaces formed with corrugations of suitable size and shape for producing the desired sheet, for example, they may measure 2H; inches from crest to crest and 1/2 inch from top of crest to bottom of groove.

A corrugated fiber sheet thereby obtained, in order to be used as a substitute for ordinary corrugated iron of 29 to 16 gauge, requires a certain strength which can be obtained only with a. certain thickness, for example U35 inch to l@ inch or more.

In attempting to produce a corrugated fiber sheet of such thicknesses, one encounters certain difficulties. On account of the thickness of the Wet lap and the fact that it is imperfectly plastic, there is a tendency for a line of Weakness to develop along the crests of. the corrugations. This difficulty I have overcome by causing the body of the Wet lap to be fluffy, that is, of great thickness in proportion to the quantity of fiber present, for example 11/2 inches to form a sheetiof 1/8 inch thickness. Such formation may be obtained by minimizing the withdrawal of Water from the sheet While it is being formed in the Fourdrinier machine or equivalent apparatus, and thereafter, and by dispensing with the use of pressing rolls, or if used, by applying only relatively low pressures. In order to produce finished sheets of great thickness, for example 1,41 inch, the water content and thickness of the wet lap should be more than proportionately increased, or in other words it should be as iu'y as possible in order to increase its plasticity and avoid formation of lines of weakness along the crests of the corrugations.

The pressing of sheets having such high Water content, however, introduces another difficulty, viz., the eiilux of water utpon a plition of pressure to the sheet ten s -to orm streams which carry away pieces or fragments'of the wet lap sheet. This diiiculty may be overcome by operating the press with sufficient slowness to permit the water to run from the material without displacement of any of the pul The press should however be'operated wit such speed that full pressure is applied to the wet lap sheet before the temperature of the surface of the material or of any portion thereof rises above 212 F. By maintaining the full pressure of the press, which may be from 200 lbs. to 700 lbs. r sq. in., upon the sheet until it is thoroug y dry, a strong, dense and perfect corrugated sheet of a thickness of 3, inch to 1A Ainch or v possibly more may be obtained. The material of such nished sheets has a very high resistance to exure, equal to that'of many Woods with the grain, and on account of the corrugated form of the sheet the resistance to liexure in one direction is vastly increased so that the fiber sheets may be used as a substitute for corrugated sheet iron for the roofing and siding of buildings, and forlother purposes. Its specific gravity. is approximately one.

. more of such sheets a in su erpose Instead of forming the corrugated sheets by the pressing and drying of a single wet lap sheet as described, I have discovered that sheets of any desired thickness may be 0btained by forming wet lap sheets in the manner previously described, arrangin two or t? relation to one another, as shown in ig. 3, and thereupon suecting the built 11p sheet or body so form to ressure and heat in the press. In this case t e wet lap does not need to be of the fluffy or ilocculent character described, but may have the free Water substantially removed therefrom before it is placed in the press, and if desired eacl'f'of the wet lap sheets may be formed with corrugations pressed or rolled therein before being placed 1n superposed relation. In the hot pressing of the built-up Wet lap sheet, one should take care as before that full pressure be applied before the platens heat the surface of the wet lap material above 212 F., and that full pressure be maintained until the builtup sheet is completely dry.

When this is done the final product is a homogeneous corrugated sheet o, as illustrated in Fig. 4, no line of demarcation being observable between its diferent layers. The separate la ers are connected or welded together by t e action under heat and pressure of the natural cementitious material of the original Wood, probably the lignins. This process just described is useful in the production not only of corrugated sheets but also fiat sheets d, as shown in Fig. 5, and fiber products of any special or desired conformation.

I claim:

1. A corrugated building board of vegetable ber hot platen pressed from a web of wet vegetable fiber until substantially dry and of substantially permanent gauge dimension and specific gravity approximately one, or more than one, same being resistant to atmospheric corrosion, andvo strength, .stiffness and rigidity suiiicient to adapt it for use as a building-material in place of corrugated iron.

2. A vegetable fiber sheet built upby the welding together of superposed layers of wet lap sheets by means of the natural cenientitious constituent of the original fibrous raw material.

3. A water resistant ve etable liber sheet formed of a pluralityo superposed layers of wet lap sheets containing a water insoluble size, said layers bein welded to- -gether by the natural cementitious constituent of the original fibrous raw material.

4. A corrugated vegetable fiber sheet built up by the welding together of superposed layers of wet lap sheets by means of the natural cementitious constituent ofthe original fibrous raw material.

5. A Water resistant corrugated vegetable fiber sheet formed of a plurality 'of superposed layers of wet lap sheets containin a Water insoluble size, said layers being weled together by the natural cementitious constituent of the original fibrous raw material.

6. In a process of making a corrugated board having great tensile strength, the steps of forming a fibrous felted sheet havin a high water content, placing said sheet Iietween heated -platens in' a press and, compressing the same ati such rate as to express the water without carrying away portions of the sheet and to `apply a high pressure thereabove the vaporizing temperature of water.

' 7. In a process of making a corrugated m,

'to before the surface of the material is heated l tween heated platens in a press and compressing the same at such rate as to express the water without carrying awa portions of the sheet and to apply a hig pressure thereto before the surface of the material is heated above the vaporizng temperature of water, and. maintaining such high pressure until the sheet is substantially dry through# out.

8. In a process of making a vegetable fiber board, the step of forminga Wet lap sheet and subjecting the same to hi h pressure between heated platens so shape as to form corrugations on the sheet, the full pressure being applied to the sheet before the temperature of any portion of its surface is raised above the vaporizing teln erature of water.

In testimony whereof have signed my name hereto.

WILLIAM H. MASON.

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