US2902720A - Method of producing an oriented reinforced artificial sponge - Google Patents

Description

Sept. 8, 1959 J. LACHICHE ETAL METHOD OF PRODUCING AN ORIENTED REINFORCED ARTIFICIAL SPONGE Filed March 27, 1957 III/III,

//Vu/vr0/5-, JUL/EN ZACH/(HES, ANDRE OR/OL BY I Arro/e/vsv A METHOD OF PRODUCING AN ORIENTED REINFORCED ARTIFICIAL SPONGE Iulien La'chiche and Andre Oriol, Paris, France, assignors to Novacel, Paris, France, a corporation of France Application March 27, 1957, Serial No. 648,868 Claims priority, application France March 29, 1956 1 Claim. (CI. 18-48) This invention relates to the production of artificial sponges and has for an object to provide artificial sponges having novel and improved characteristics.

Artificial sponge materials are often reinforced by incorporation of various types of fiber. This is particularly the case where regenerated cellulose is concerned.

These fibers are introduced into the liquid or viscous mass before regeneration, polymerization or insolubilizing the material.

The fiber is a very important factor of the overall solidity of the product, and its influence upon solidity is governed by the type of fiber, its quantity, the dimensions, the distribution thereof through the material, and their orientation relative to the center-point of the mass.

Absence of orientation in any specific direction results in the production of a spongy mass of homogeneous solidity in all directions. Preferential orientation in a given direction makes the material more resistant to compression in the plane perpendicular to the direction of primary orientation, greater resistance to stretching in the direction of orientation, and greater resistance to flexure in the plane perpendicular to that of orientation.

Certain special uses of these spongy materials require maximum resistance to wear in a given plane, this being the working plane determined by the equipment or conditions of use.

The present invention provides an improved procedure for filling molds with the plastic mass in such a manner that preferential orientation of the fibers in the mass is obtained before coagulation.

More specifically the method involves forcing the material to be treated through a screen of specific mesh, the bars of the screen serving to calender the material and cause orientation of the fibers in the direction of flow, due to friction against the bars.

The fibers thus undergo preferential orientation in the direction of flow, and retain this orientation if means are provided to assure that upon entry into the mold, the mass is completely restricted and therefore incapable of moving in any direction other than that by which it entered, as other motion would destroy the orientation.

The screen specification (size and form of the openings, size and form of the bars), which may be dependent upon extraneous factors, not having to do with the results desired (for example, the viscosity of the matter), permit manipulations with greater or lesser fractions of the mass being processed, and thus permit control of the degree of orientation.

Thus, a screen with small, close mesh, will cause orientation of virtually all the fibers, while one of coarse mesh causes only zones, larger or smaller in size, of primary orientation. As a result, the screen must be particularly adapted to the result desired, i.e., to the eifect of orientation upon the results of employment cf the finished spongy material.

The invention is more readily understood with the aid of the specific examples given below, but it will be understood that these examples are by no means restric- Patented Sept. 8, 1959 2 tive, the invention being applicable to various modifications and adaptations.

In the drawings:

Fig. 1 is a perspective View of a mold and screen illustrating one embodiment of the invention with the front and end wall of the mold removed to show the construction of the parts;

Fig. 2 is a vertical section through a mold and filling mechanism illustrating a further embodiment of the invention; and v Fig. 3 is a broken perspective view of a further embodiment wherein the mold is stationary.

Referring to the drawings more in detail, a closed mold 10 is shown in Fig. 1 having a top closure member 11. A screen 12 conforms generally to the area of the mold and is mounted on a frame 13 for vertical movement in the mold to the dotted position 14 below the topclosure 11. The frame 13 is raised by suitable means not shown.

The mold is filled with the sponge forming material with the screen 12 in its lower position. The top closure 11 is then placed over the material and the frame 13 and screen 12 raised to the dotted position. This motion of the screen forces the sponge forming material through the mesh of the screen 12 and orients the fibers as above described.

The mass is then retained in the mold without further movement while the solidifying reaction takes place. The sponge thus formed will have its fibers oriented vertically due to the calendering and friction of the screen elements produced by the movement of the screen through the unreacted material. Conversely the screen may be positioned initially at the top of the mass and forced downwardly therethrough if desired.

Fig. 2 illustrates an embodiment wherein the sponge forming material is fed by a screw conveyor 20 through a feed chamber 21 terminating in a flared wall 22 having an open end 23 corresponding in size to the area of the mold 24 and provided at its open end 23 with a screen 25, similar to the screen 12 of Fig. 1. The mold 24 is mounted for limited vertical movement in response to the pressure of the sponge forming material against the pressure of supporting springs 26.

In this embodiment the sponge forming material is extruded into the mold 24 through the screen 25 which serves to orient the fibers as above described. After entering the mold no further movement of the mass takes place until the artificial sponge is removed after the solidifying reaction. Hence the sponge contains fibers which are oriented in the vertical plane.

Fig. 3 shows an embodiment wherein an upper mold 30 having a screen 31 across the bottom thereof is disposed above and in registration with a lower mold 32 having a closed bottom.

The upper mold 30 is filled with the sponge forming material by any suitable means and the material is then forced by suitable pressure means through the screen 31 and into the lower mold 32 wherein the solidification reaction takes place.

In this embodiment as in the previous forms, the fibers are oriented in passing through the screen and retain their orientation during the solidification reaction.

What is claimed is:

The method of forming artificial sponges composed of regenerated cellulose containing reinforcing fibers which comprises extruding a cellulosic sponge-forming material in the form of a viscous mass containing randomly dispersed reinforcing fibers into a mold of uniform cross sectional area, passing through said mass while in a form having the cross sectional area of said mold a screen extending entirely across said area, said screen having a mesh to reorient said fibers while passing therethrough 3 into the direction of said passage and to calendar the mass of cellulosic material, subjecting said mass to a solidifying reaction after passage of said screen therethrough, whereby the fibers retain their orientation in the solidified sponge.

Shrady June 30, 1896 Morrison Nov. 3, 1896 4 Alexander Aug. 29, 1905 Riesch Dec. 19, 1911 Wyatt et al. May 1, 1934 Frendenberg et al Apr. 12, 1938 Vantier May 10, 1938 Holzapfel Nov. 1, 1938 Braker June 13, 1939 Banigan et a1 Apr. 14, 1942 Saint Dani's June 20, 1950 Fisch June 29, 1954 Seipt Aug. 23, 1955'

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