US3473884A - Web treating method - Google Patents

Description

una): lvl l l lvjglll Oct. 21, 1969 A. PoLlTzl-:R` ErAL WEB TREATING METHOD Filed June 20, 1966 f, uw

United States Patent O 3,473,884 WEB TREATING METHOD Alfred Politzer, Fairview Park, and Otto V. Drtna and Joseph S. Bedoch, Lakewood, Ohio, assignors to Nylonge Corporation, Cleveland, Ohio, a corporation of Ohio Filed June 20, 1966, Ser. No. 558,661 Int. Cl. D0613/08 U.S. Cl. 8-108 1 Claim ABSTRACT OF THE DISCLOSURE A freshly produced sodium sulfate containing regenerated cellulose sponge web is advanced in zig-zag fashion across successive liquid catch basins, liquid being expressed from the web at the apices of the web path. Fresh and recirculated water and freshly replenished and recirculated hypochlorite bleach solution are applied to the other upper parts of the web.

The present invention relates generally to improvements in the production of regenerated cellulose products and it relates more particularly to an improved method and apparatus for the continuous treatment of freshly regenerated cellulose sponge webs to effect the washing and purification thereof.

Artificial cellulose sponge, either in cloth or block form, is conventionally produced by the viscose process, a sponge forming mass comprising a mixture of viscose, reinforcing fibers and a particulate pore forming material, such as sodium sulphate decahydrate, being treated, usually by heating, to coagulate the viscose and regenerate the cellulose therein. The resulting sponge must then be after-treated to remove the sodium sulphate and the byproducts of the cellulose regeneration, bleached and additives such as plasticizers, fungicides and the like added. In U.S. Patents Nos. 2,899,704 and 2,989,775 granted to F. Pekarek Aug. 18, 1955, and lune 27, 1961, respectively, there are described methods and apparatus for the production of regenerated cellulose sponge cloth as a continuous web, the freshly regenerated web being subjected to various aftertreatments while continuously advanced to effect the purification and treatment thereof. The process and apparatus heretofore employed for effecting the aftertreatment of the freshly produced regenerated cellulose sponge web, while satisfactory, possess drawbacks and disadvantages. The equipment required is large and bulky and highly space consuming and the process is inefficient and otherwise leaves much to be desired.

It is, therefore, a principal object of the present invention to provide improvements in the production of regenerated cellulose products, such as sponge, sheeting, and the like.

Another object of the present invention is to provide an improved method and apparatus for the continuous aftertreatment of an advancing web of regenerated cellulose.

Still another object of the present invention is to provide an improved method and apparatus for the washing, purification and liquid treatment of a continuously advance web of regenerated cellulose sponge.

A further object of the present invention is to provide an apparatus and method of the above nature characterized by their efiiciency, adaptability, reliability, relatively high capacity and small space requirements.

The above and other objects of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawing which is a longitudinal view of an apparatus ICC embodying the present invention and which may be employed for practicing the present process.

In a sense, the present invention comprises the method of treating a freshly regenerated cellulose web comprising advancing said sponge web along the length thereof in a plurality of successive downwardly forwardly inclined and upwardly forwardly inclined runs, and applying a treating liquid to said web at the upper parts of said inclined runs. An improved apparatus which may be employed in practicing the present process comprises a plurality of longitudinally spaced transversely extending driven rollers, a plurality of longitudinally spaced transversely extending guide bars disposed below and between successive of said rollers, said web traversing a path over and under successive of said rollers and bars respectively, a liquid receiver positioned below and in alignment with the space between each successive pair of rollers, a liquid distributing member extending across the width of said web adjacent each of said rollers applying liquid to said web at the upper parts of each of the inclined runs thereof, and means for circulating water from at least one of said receivers to at least one of said distributing members.

According to a preferred form of the present apparatus theer are provided seven successive rollers, successive liquid receiver defining tanks registering with the space between each adjacent pair of rollers, the guide bars being disposed in the respective tanks above the liquid level therein. A liquid distributor in the form of a gravity spray manifold is positioned on opposite sides of each of the rollers between the end rollers and along the inside faces of the end rollers and a squeeze roll engages each of the rollers except the leading roller. The liquid in the first tank is recirculated to the first spray manifold and fresh water is metered to the second manifold. Liquid from the fourth tank is circulated to the third and fourth spray manifolds, liquid from the third tank is recirculated through the fifth and sixth spray manifold, a bleaching solution being metered to the fifth spray manifold, liquid from the fifth tank being circulated to the seventh and eighth spray manifold, fresh water being fed to the ninth and tenth manifold, the liquid in the sixth tank being recirculated to the eleventh and twelfth spray manifolds, and additive solutions are fed to the eleventh spray manifold.

It has been found that as compared with the methods and apparatus heretofore employed in the liquid treatment of freshly regenerated cellulose sponge :the present method is of high efiiciency and a greater extraction and recovery of the sodium sulfate carried by the sponge web is achieved. Furthermore, for the same treating capacities, the present apparatus is about one half the size of the heretofore employed equipment with the correspondingly lower space requirements, costs and other advantages. It is believed that many advantages of the present apparatus and process are achieved for among other reasons that the treating liquids are applied with a component parallel to the plane of the web. The pores in a continuously produced regenerated cellulose sponge web are oriented along the plane of the web and liquids traveling through the web with a component along the plane thereof and at an angle thereto appear to be more effective than the conventional procedures. In addition, a countercurrent and cocurrent treatment of the advancing web is effected. It should be noted that when treatment is referred to this may be an extraction, treatment, such as bleaching, a washing or an additive step.

Referring now to the drawings which illustrate a preferred embodiment of the present invention, the reference numeral 10 generally designates the improved apparatus for treating a regenerated cellulose sponge web W which may be continuously produced in any known manner, for example as described in the above identified Pekarek patents. The web W may be of any .desired thickness, for exam-ple between 1A inch and 3 inches, and preferably corresponds in width to that of the apparatus 10. The web W as it enters the apparatus has been freshly coagulated as by being heated either by passing a current therethrough or |by subjectnig it to a hot sodium sulfate solution and is impregnated with sodium sulfate and by products of the regeneration of the cellulose.

The apparatus 10 includes a plurality of successive longitudinally spaced transverse parallel rollers 11 to 17 respectively which are supported at substantially the same level and are positively rotated in the same sense, clockwise as viewed in the drawing, at the same adjustable peripheral speed, in any suitable manner. A squeeze roll 18 is associated with each of the rollers 12 to 17 and are spring urged under adjustable pressures into contact with the upper faces thereof, the squeeze rolls 18 advantageously being positively driven at the same peripheral speeds as the rollers 12 to 17 but in opposite directions.

A plurality of successive liquid receivers or tanks 19 to 24 are disposed below the rollers 11 to 17 the tanks 19 to 24 registering with a corresponding space between successive rollers 11 to 17 respectively. The width of the tanks 19 to 24 is somewhat larger than the width of the web W and the end walls thereof are in vertical alignment with the axes of the rollers 11 to 17. A transversely extending cylindrical guide bar 26 is positioned in each of the tanks 19 to 24 above the liquid level therein and while illustrated as positioned along the medial transverse axes of the respective tank it may be longitudinally offset relative thereto.

Extending along the upper leading face and for substantially the full length of the roller 11 is a liquid spray or distributing manifold 27 and a similar spray manifold 28 extends along the upper trailing face of the roller 12. A pair of spray manifolds 29 extend along the confronting upper faces of the rollers 12 and 13, a pair of spray manifolds 30 and 32 extend along the upper confronting faces of the rollers 13 and 14 respectively, a pair of spray manifolds 33 extend along the confronting upper faces of the rollers 14 and 15, a pair of spray manifolds 34 and 36 extend along the upper confronting faces of the rollers and 16 respectively, and a pair of spray manifolds 37 extend along the upper confronting inner faces of the rollers 16 and 17. Each of the spray manifolds 27 to 37 is advantageously in the form of an open topped elongated trough providing with opposite bottom walls converging downwardly to a medial transverse outlet which may be in the form of an elongated slit or a plurality of small transversely spaced openings whereby to provide a descending sheet or spray of liquid from the corresponding trough.

A liquid pump 38, preferably of the centrifugal type, has its inlet and outlet connected by suitable piping to the bottom of the tank 19 and the distributing manifold 27 to circulate liquid from the tank 19 to the manifold 27. Similarly, a pump 39 recirculates liquid from the tank 21 to the distributing manifolds 30 and 32, a pump 40 circulates liquid from the tank 22 to the manifolds 29, a pump 41 circulates liquid from the tank 23 to the manifolds 33, and a pump 42 recirculates liquid from the tank 24 to the manifolds 37. The tanks 19, 20 and 22 are provided with adjustable overflow pipes to maintain the liquids therein below a predetermined level, the overilow of the tank 19 being led to a sodium sulfate salt recovery system. An adjustable liquid metering device 43 having an input connected to a source of water and an output connected to the manifold 28 feeds measured quantities of water to the manifold 28. Similarly, a metering pump 44 feeds a bleach buck-up solution -to the manifold 30, a metering pump 46 feeds an anti-chlolbuck-up solution to the manifold 34, a metering device 47 feeds water to the manifolds 34 and 36 and a metering pump 48 feeds an additives solution such as one containing fungicides and other additives to the tank 24.

In employing the above apparatus in the practice of the present method, the sodium sulphate impregnated freshly regenerated cellulose sponge web W produced by the viscose method, as set forth above, advances from the sponge producing regenerating section through the apparatus 10 along a traversing zigzag path over the successive rollers 11 to 17 and under the guide bars 26. The web W which may be of a thickness between 1A: inch and 3 inches may be advanced at a speed between 5 and 45 inches per minute by adjusting the speed of the rollers 11 to 17 The concentration of the various treating solutions, the rate of flow of the treating liquids and the times of exposure of the webs thereto depend on the thickness of the web W and other parameters. The following procedure is advantageously employed in the treating of a freshly regenerated cellulose sponge web of a thickness of between 1A inch and 3 inches and a width of about 36 inches, the rate of advance of the web being between 5 and 45 inches per minute and the length of the web W between rolls 11 and 12, between rolls 12 and 13, between rolls 13 and 14, between rolls 14 and 15, between rolls 15 and 16, and between rolls 16 and 17, each being only about a few feet.

Water is metered into the spray manifold at a rate of between 1000 and 5000 cubic centimeters per minute and is applied to the upward run of the web W as it approaches the roller 12. The fresh water travels countercurrent through `the upwardly travelling web W passing through the web W at an angle thereto and leaching sodium sulphate and other impregnants therefrom, the sodium sulphate carrying liquid falling into the tank 19. The pump 38 recirculates the liquid in the tank 19 to the distributor 27 which applies it cocurrently to the downwardly travelling web W to initiate the sodium sulphate extraction therefrom. The liquid in the tank 19 is recirculated at a rate between l0 and 30 gallons per minute and the overow liquid from the tank 19 is led t0 a sodium sulphate crystallizing apparatus.

While the we-b W, in travelling around the roller 12, may have liquid expressed therefrom by the squeeze roll 18, the expressed liquid owing into the tank 19, it is preferred not to squeeze express liquid therefrom at this stage to facilitate the leaching of the sodium sulphate. The wash water from the tank 22 is pumped to the distributors 29 which apply it to the web W between the rollers 12 and 13 to substantially free the web W of sodium sulphate and some of the other regeneration by-products. The wash water passes angularly through the web W and travels cocurrently and countercurrently along the successive runs, falling into the tank 20 from which it is discharged. Excess water is expressed from the web W between roller 13 and squeeze roll 18 and flows into the tank 20.

In the travel of the web W between the rollers 13 and 14 a bleaching solution which is recirculated from the tank 21 to the distributors 30 and 32 is applied to the web. In addition, a buck-up bleach solution is metered into the distributor 30. The pump 39 recirculates the bleach solution at a rate of between 20` and 60 gallons per minute. The bleach solution may be an aqueous solution of sodium hypochlorite at a concentration of between 0.5 and 5.0 grams per liter. The quantity of the buck-up solution metered by the pump 44 and the concentration thereof should be suicient to maintain the desired concentration of the solution in the tank 21 and to maintain a suitable level in the tank 21.

Following the expression of excess bleach solution from the web W by the roller 14 and squeeze roll 18, the solution returning to the tank 21 by way of the web W, the web W in its travel between the rollers 14 and 15 is subjected to a wash by the anti-chlor and wash liquid circulated from the tank 23 to the dStributOrS 33 preferably at a rate of between .5 and 20 gallons per minute. The liquid is then expressed from the web W between the roller 15 and squeeze roll 18 and in the downward run of the web W from the roller 15 it is subjected to a spray from the distributor 34 of a fresh anti-chlor solution as controlled by the metering pump 46 and the water metering device 47. The pump 46 delivers between 7 and 750 milliliters per minute of a solution of sodium bisulphate or sodium thiosulphate at a concentration of about 2.4% and the metering device 47 delivers fresh water to each of the distributors 35 and 36 at the rate of between 2.5 and l0 gallons per minute to each distributor. Between the rollers 16 and 17 a suitable fungicide solution is applied to the web W as recirculated from the tank 24, a buck-up solution being metered thereto by the pump 48. Excess solution is expressed from the web W between the roller 17 and squeeze roll 18 and returned to the tank 24, the web W then being led to further handling equipment.

It should be noted that the angles of the inclined runs of the web W to the horizontal are advantageously between 30 and 60, the angle preferably being less Where a chemical reaction is effected by the treating liquid and preferably greater when washing or leaching is effected. With increased web thickness greater treatment time is desirable and hence longer web paths or less advancing speeds and the liquid circulating rates are correspondingly modified.

What is claimed is:

1. The method of treating a freshly regenerated cellulose sponge web initially impregnated with sodium sulfate comprising advancing said sponge web along the length thereof along successive rst, second, third, fourth, fth, sixth, seventh and eighth successive alternating downwardly and upwardly inclined runs, and expressing liquid from said web along the upper parts of said runs, applying water to said second run and recovering said water in an underlying first liquid receiver, discharging liquid from said rst receiver and recirculating liquid UNITED STATES PATENTS 2,265,033 2/ 1941 Fryer et al. 8-108 2,382,726 8/1945 Korte et al. 68-22 2,521,748 9/ 1950 Rodgers 8-108 XR 2,925,088 2/1960 Roscoe S-IOSXR 3,140,146 7/ 1964 Synan et al. 8-108 MAYER WEINBLA'IT, Primary Examiner U.S. C1. X.R. 68-9, 22, 205

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