US2395218A - Felted wood fiber machinable corksubstitute material - Google Patents

Description

Feb. 19, 1946. j GAUTH|ER 2,395,218

FELTED WOOD FIBER MACHINABLE CORK-SUBSTITUTE MATERIAL Filed Dec. 22, 1941 JOSEPH H. GAUTHIER INVENTOR.

ATTORNEYS Patented Feb. 19, 1946 FELTED WOOD FIBER MACHINABLE C(ERK SUBSTITUTE MATERIAL Joseph H. Gauthier, Los Angeles, flalii. Application December 22, 1941, Serial No. 424,070

' 1 Claim. 01. 92-3) This application is a continuation in part and completion of my-application for patent filed October 30, 1940, Serial No. 363,516.

The purpose of my invention is to provide a sheet of felted wood fiber which has the same qualities, or characteristics, as good hard commercial cork with regard to firmness, stability, resiliency, and machinabllity, and therefore may be used as a substitute for cork. Such material has many uses in industry as a component part of manufactured articles. One of its immediate important uses is for making shoe soles and heels, particularly heels for women's shoes. Cork has heretofore been generally used for the making ofwomens play-shoes," or lower-heel type of shoes; but, because of the present European war, good cork is very diflicult to obtain, and no suitable substitute for it was known before my invention.

The qualities which the substitute must possess are firmness and resiliency and machinability of good hard cork. offering resistance to flaking and breaking down at the surface edge, for example, at the back edge of a shoe heel.

An essential property which my cork substitute material possesses, similar to cork, is resiliency or the quality of springing back-the so-called come-back--to the original thickness imme diately after being released from severe compression. When a cork heel is fastened to the sole of a shoe these parts are placed in a sole-laying machine and a pressure of about 40 to 200 pounds to the square inch is applied to the heel. This pressure temporarily reduces the heel material to approximately 75% of its original thickness. Therefore the heel must be able to spring back to its initial thickness upon release from compression otherwise the leather covering of the heel would wrinkle on the heel and render it unsightly.

A further quality possessed by my material, essential for making shoe heels, is that the finished heel does not unduly compress, nor flake at the edge, under normal walking pressure, nor crack at the thin tapering shank portion of the sole.

I discovered that long wood fibers, such as are obtainable from the wood of spruce and other conifers, excluding red fir, redwood, and red or white, cedar, and, in particular, the fibers obtainable from Sitka spruce, when combined with a certain amount of partially hydrated chemical wood pulp, such, for example, as kraft" pulp, used in paper making, may be feltedinto a sheet having all the essential characteristics of good hard cork, and especially suitable for making shoes of the type mentioned.

' The fiber component of my material must be processed to remove the acidity of the wood, without removing the natural lncrustations of' the fibers, the removal of which would take from the fibers their natural resiliency.

The fiber component I produce by reducing blocks of coniferous woods, of the kind mentionedf to chips of about .flve-elghths of an inch in length. These chips I cook in a digester In a weak alkaline liquor, to neutralize the watersoluble acids contained in the wood. Lime may be used because of its'cheapness for making the liquor. The acids must be removed from the chips, because, if permitted to remain, they would tend to produce brittleness in the fiber. The acids also tend to attack the adhesives, by which initial units of my material may finally be cemented together in laminated form to produce a sheet of the required thickness, for example for producing shoe heels.

The alkaline liquor I hold at about 320 F. for three hours (more or less), rotating the digester slowly. I make tests of the liquor during the cooking of the chips to ascertain whether their acidity has'been sufilciently neutralized. The described soaking of the chips also softens the fibers and facilitates their later mechanical defiberization, as is well known in the art.

The alkaline liquor must not be of such strength as to afiect the lignin, or natural incrustations of the fibers, since these incrustations are essential to retain in the fibers their natural stiifness and resiliency, as previously mentioned.

The fibers obtained from spruce and other coniferous woods, as above specified, I found by actual tests to be the only kinds of fibers suitable for producing my material since they possess the compressibility, high resiliency, and also the comeback required to cause my material to spring backinto original thickness after having been forceably compressed approximately onefourth in volume, this being an essential quality in material to be used for making the heels of women's shoes in order to assure'a smooth facing in the leather covering the heel, as above-mentioned.

After the acid-removing cooking is completed the digester is drained off and the chips should be subjected to two successive washings, to remove all dissolved material. I then take the chips out of the digester and carry them to refining equipment for disintegration into relatively long fibers, about one-eighth to three-eighths of an inch in length.

The refining devices must be set, or controlled, to produce fibers not less than one-eighth of an inch long. Shorter wood fibers would not possess the essential resiliency for the use of my material for the purpose mentioned. Therefore, too many fines must be avoided; and if too many fines should occur because of improper control, they should be eliminated by screening the fiber through aZB-mesh standard screen or equivalent means, and rejecting the fines which pass through the screen.

The bonding component of my material may consist of kraft or sulfite pulp as produced for paper-making. The bonding component should have the characteristics of kraft pulp such as used for making strong paper. By this I mean that the cooking process for producing the. pulp, whether an acid or an alkali be used in such process, must be stopped short of the time which would remove all 'the lignins and natural incrustations; for the complete removal of all the lignins and natural incrustations in the cooking process would render the pulp produced unsuitable as the bonding component of my sheet. Such chemical pulp should be partially hydrated in the usual refining equipment, and in that condition will intermesh with the coniferous fibers to form an integral, resilient sheet. This bonding component shrinks to some extent when dried, thus adding strength to the sheet of felted material. The bonding component must not be completely hydrated because with complete hydration the character of the fibers is changed, in other words'they lose their identity as fibers and become converted into a gelatinous mass, drying into a hard, horny, brittle substance, as well known in the art.

But due to the presence of the coniferous fibers and the fact that the chemical bonding pulp is only partially hydrated, the contraction or shrinkage of the felted sheet will not cause the sheet to reach the stage of a board-like; horny or brittle character which would be the very opposite of the required characteristics of my material. In the making of my material I add about 15% to 20% by weight of the chemical pulp (based on dry weight of the fiber component) in the form of a slurry of about 95% water consistency, and thoroughly intermix the resulting mass. The chemical pulp becomes thoroughly intermeshed and interlaced with the coniferous fibers in the making of the mat or sheet of my material, and the chemical pulp, pulls the coniferous fibers firmly together and contributes to imparting to the finished sheet the required tensile strength and stability, and the property of permitting ample flexing without breaking at a thin or tapering portion. The resilient quality of my material can be demonstrated by throwing a piece on the ground; it will bounce just like a piece of cork.

In order to render my material moisture repellant tothe degree required for the intended use of the material, I add rosin alum.

The intermixed mass or stock has an approximately 98 percent consistency of water. I then discharge the stock for making my material on the wire of a Fourdrinier machine, on which the mat is passed through presses in which its moisture content is reduced to about 60 percent. The sheet of material coming from the presses should preferably be about one-half of an inch thick. The sheet is then passed through a dryer and its moisture content reduced until this does not exceed 5%. In this step the sheet acquires moisture-resistant quality, if containing moisture proofing ingredients.

' cork.

In order to assure in the finished sheet the desired density, firmness and tenacity of bond, I dry the same in a Coe dryer, at a temperature of about 270, F. in the first section of this dryer, and reduce the temperature in the last section of the dryer to the degree required for reducing the moisture in the sheet as stated.

The shrinkage of the material in drying is such that a one-half inch mat going ihto the dryer on the wire is reduced to about athree-eighths of an inch sheet when dried. This is just about the right thickness for the sheet, in order to as;

square inch, reducing the stacked units about l8 percent in thickness. The laminated material is held in the press under sufiicient pressure, to assure good bond at the glue line, for about 20 hours and until the bond of glue is thoroughly set. When the laminated sheet is taken out of the press it will immediately come back substantially to the initial thicknessof the stack of thin sheets cemented together. The laminated sheet so produced has a density of about 23 to 28 pounds to the cubic foot.

For some heels made of my material the usual dowel may be omitted, because, due to its density as well as resiliency, my material is superior to In the accompanying drawing constituting a part of this specification:

Fig. 1 shows a diagrammatic side elevation of a woman's shoe of the play-shoe style, having a one-piece heel-and-sole section made of my material; part of the outer covering or facing being. shown as removed; and Fig. 2 shows a similar diagrammatic side elevation of a diilerent style of women's shoe, in which the heel and sole portions of the shoe are connected by an arch.

In Fig. l, (1' represents the upper portion of a woman's shoe of the play-shoe type, b the inner sole to which is attached the combined sole and heel piece 0, made of thin laminated sheets d of my material; e is the outer or bottom sole, and f, the leather covering or facing applied to the heel portion of piece 0. Due to the resiliency or" my material the piece 0 may be tapered at g; and will still retain resistance to cracking at the tapered section.

In a shoe of the type illustrated by Fig, 2 the heel section 2' is supported by a steel shank h. The heel-piece will not flake off at the edge, and the heel piece will resist such compression as would cause the leather covering to wrinkle, and render it unsightly.

My description of the specific use of my mate'- rial for making shoes is merely intended to describe one use thereof.

While the relative proportionsof the components of my cork substitute may be somewhat varied, I have found, after extensive tests, that the directions above given can be depended upon as producing a material Well adapted for use for the making of shoe soles and heels and other tially hydrated chemical wood pulp, said matearticles requiring sheets of the thickness specifled as a substitute for good hard cork.

I claim: i

A felted wood fiber curb-substitute material comprising about eighty percent of substantially rial being in the form of a felted sheet about three-eighths of an inch thick and having a density of twenty to twenty-four pounds per cubic foot, said sheet being compressible and, when compressed to approximately seventy-five per-' cent of its initial thickness, having a. "come-back returning it. closely to its initial thickness upon release from compression. 1

JOSEPH H, Ga;

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