US3048888A - Apparatus for the production of artificial sponge - Google Patents

Description

3 Sheets-Sheet l IN V EN TORS AT TO RNEY Aug. 14, 1962' A. sHocKLEY ETAL APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SPONGE Filed Feb, 5, 1960 Aug. 14, 1962 A. SHOCKLEY ETAL 3,048,888

APPARATUS FOR THE PRODUCTION OP ARTIFICIAL SPONGE Filed Feb. 5, 1960 5 Sheets-Sheet 2 INVENTORS ALVIN SHOCKLEY JAMES TE NG ATTORNEY Aug. 14, 1962 A. sHocKLE-Y ETAL 3,048,888

APPARATUS FOR THE PRODUCTION OP ARTIFICIAL SPONGE Filed Feb. 5, 1960 5 Sheets-Sheet 3 FIG.6 47 47 INVENTORS ALVIN SHOCKLEY 5 BY JAMES TENG ATTORNEY United States @hice Ohio Filed Feb. S, 1960, Ser. No. 6,931 11 Claims. (Cl. 18-5) The present invention relates generally to improvements in equipment for the manufacture of artioial sponge and it relates more particularly to an improved apparatus for the continuous coagulation and regeneration of a viscose sponge forming mass.

In the manufacture of artificial regenerated cellulose sponge `by the viscose process, a relatively green viscose of high viscosity is produced in the conventional manner and is then admixed with reinforcing bers such as cut hemp or the like, land a granular pore forming material such as sodium sulphate decahydrate. The resulting sponge forming mass is Ithereafter deposited in `large molds or forms in various manners and the viscose coagulated, the cellulose regenerated `and the pore forming material leached out to produce a block of the artificial sponge material which is then washed, bleached, plasticized and otherwise treated, dried and cut to the desired shapes. Many methods have been employed to effect the coagulation and regeneration steps including the immersion of the sponge mass containing molds in ya hot salt solution or an acid bath, heating the sponge mass in an autoclave or by passing Ian electric current therethrough. These various coagulation processes are usually of a batch nature and `are highly time and labor consuming, expensive and often difcult to control. Many continuous viscose sponge coagulating processes have been proposed but none of these have proven satisfactory and they are generally limited to masses of small cross section and possess numerous other drawbacks and disadvantages.

It is therefore a principal object of the present invention to provide an improved apparatus for the production of tartilicial regenerated cellulose sponge.

Another object of the present invention is to provide an improved apparatus for the coagulation and regeneration of a viscose sponge forming mass.

Still another object of the present invention is to provide an improved lapparatus for the continuous electrical coagulation and regeneration of a viscose sponge forming mass.

A further object of the present invention is to provide an apparatus of the above nature characterized by its ruggedness, simplicity, ease of operation and the uniformity and high quality of the product produced therewith.

The Iabove and other objects `of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a top plan view of an improved apparatus embodying the present invention;

FIGURE 2 is a side elevational view thereof;

FIGURE 3 is an enlarged plan view of the coagulation section of the apparatus;

FIGURE 4 is a sectional view taken along line 4--4 in FIGURE 3;

FIGURE 5 4is an enlarged sectional view taken along line 5--5 in FIGURE 4; `and FIGURE 6 i-s an enlarged sectional view, partially broken away, taken along line 6 6 in FIGURE 5.

ln a sense the present invention contemplates the provision of an improved apparatus for the continuous coagulation of a viscose sponge forming mass comprising a longitudinally extending trough, an endless belt conveyor having7 an upper Irun extending along the base of said trough and advancing lfrom a feed end toward a discharge end, a pair of -mutually insulated sets of electrodes disposed along opposite sides of said trough and travelling in the direction of advance of said Ibelt conveyor, and means `for depositing a sponge forming mass in said trough and upon said 'belt conveyor adjacent to the feed end thereof.

According to a preferred `form of the present apparatus the trough is of channel .shaped conguration formed of an insulating material and having metal plates extending along its inner side faces. A drum is disposed adjacent each end of the trough, the upper surfaces thereof being disposed a short distance above the ybase of the trough, the 'belt conveyor passing about the drums and having an upper advancing run extending downwardly from the trailing drum to the trough ibase, along the trough base and upwardly to the leading drum. Channel members are disposed along the upper edges of the troughs and define tracks along which advance roller chains supported 'by sprocket wheels and returning along vertically spaced horizontal paths. Each of the alternate cha-in links carries an electrode defining rectangular metal plate :which depends from lthe chain along its forward run and travels along the trough inner side .-faces and in edge to edge relationship. The roller chain is driven at a slightly greater speed than the conveyor belt. A hopper is located in lthe feed end of the trough and is provided with -mass orienting and retarding `tbalfles and is connected to a source of viscose. The bottom of the trough is tapped and liquid flowing therefrom is lrecirculated into the top of the trough. As =will be hereinafter set forth in greater retail, sponge forming mass flows from the hopper into the trough upon the conveyor which carries it along the trough. The electrode sets, which are `mutually insulated are connected -to a source of alternating current whereby to heat and coagulate the travelling sponge forming mass. The path of the conveyor and the recirculating lluid assures the uniform treatment of the mass by controlling the curent distribution therethrough.

Referring now to the drawings which illustrate a preferred embodiment of the present invention, the reference numeral 11i? generally designates the improved continuous coagulating apparatus and 11 a coagulated mass discharge table. The -coagulating apparatus 1i) includes a longitudinally extending support `frame 1-2 on 'which is mounted an open ended elongated channel shaped trough i3. Also mounted on the support frame 12 adjacent to opposite ends of the trough are a trailing drum 14 affixed to a shaft `ll and a leading drum 17 axed to a shaft 18, the shafts 16 and 18 being journalled on the .frame 12 and carrying sprocket wheels 19 and 20 respectively. The sprocket wheel 19 -is c-oupled iby ya sprocket chain to a sprocket wheel mounted on the output shaft of a variable speed reduction unit 21 driven by an electric motor 22 by way of an elongated shaft 23. The

sprocket wheel 19 is coupled =by a sprocket chain to a sprocket wheel mounted on the output shaft of a variable speed reduction unit 2S likewise driven by the electric motor 22.

The trough 13 is formed of a rigid electrically insulating material such as Wood and includes a pair of substantially vertical side Walls 24 which preferably converge slightly yfrom the trailing to the leading end thereof and a horizontal bottom or base 26 which is disposed lbelow the upper edges of the drums 14 and 17. The inner faces of the trough 13 are lined with a liquid impermeable insulation coating or sheet 27 of rubber, polyethylene, or the like which extends across the upper edges of the side walls 24 and a short distance downwardly `along the outer faces thereof. Superimposed upon the liner 27 along the trough side Walls are longitudinally extending metal plates 28 |which are suitably Aaffixed to the trough side walls 24.

Formed in the trough base 26 and spaced along the length thereof are a plurality of openings which are provided with depending valved open bottom short conduits 29 discharging into a pan 30, the openings communicating in any suitable manner with the interior of the trough. A plurality of downwardly directed spray pipes 32 are located above the trough 13 and are connected by way of a driven pump 33 and associated piping to the pan 30. Thus liquid can be adjustably bled from the bottom of the trough 13 and recirculated into the top thereof.

A conveyor belt 34 formed of cord reinforced rubber or other electrically insulating flexible material is engaged and driven by and extends between the drums 14 and 17. the upper advance flight of the belt 34 traverses a trailing downwardly inclined run 36 from the upper edge of the drum 14 to the trough base 26, a horizontal run 37 along the trough base 26 and an upwardly inclined leading run 35 to the upper edge of the drum 17. The belt 34 traverses a horizontal return run between the lower edges of the drurns 14 and 17 It should be noted that the variable speed drives 21 and 25 are adjusted so that the drum 14 is driven at a greater peripheral speed than the drum 17 and that there is slippage between the drum 14 and belt 34. Thus the return run of the belt 34 is horizontal and taut whereas the advance run thereof is as illustrated and described.

The electrode system includes a pair of longitudinally inwardly facing track defining metal channels 39 mounted in the upper edges of the trough side walls 24 and extending to points short of the side wall ends and terminating in upwardly inclined directing strips. Suitably journalled above the trough 13 adjacent to opposite ends thereof are a pair of parallel transverse shafts 40 theI opposite sections of which are electrically separated by one or more insulator couplings 41. The leading shaft 40 has axed thereto a sprocket wheel 42 which is coupled by way of a sprocket chain and a variable speed reducing unit 43 to the drive motor 22. Mounted on and adjacent to opposite ends of each of the shafts 40 are sprocket wheels 44, each set of longitudinally spaced sprocket wheels 44 being substantially coplanar with a corresponding track 39. Engaged and driven by each set of sprocket wheels 44 is a roller carrying sprocket chain 46 having an upper horizontal return run and an advance run including a trailing downwardly inclined flight from the sprocket 44 to the track 39, a horizontal flight along the track 39 and an upwardly inclined leading ight from the track 39 to the leading sprocket wheel 44.

The sprocket chain 46 is of conventional construction including successive pairs of transversely spaced links 47 and 48 respectively pivotly joined in the usual manner by transverse pins 49 on which are mounted rollers 50. When the sprocket chains 46 traverse their horizontal advance runs along tracks 39 the rollers 50 ride along and register with the tracks 39 and the inner links 47 are disposed inwardly of the inner faces of the trough side walls 24. Each of the inner links 47 is provided with depending bracket plate 51. Secured to each of the bracket plates 51 by nuts and bolts or other suitable separable fastener is an electrode defining substantially rectangular metal plate 52 which is coplanar with the corresponding supporting link 47. The electrodes 52 depend from the links 47 which register with the track 39 and extend substantially to the trough base 26. The ruuter faces of the electrodes 52 slide along the metal plates 28 and the adjacent side vertical edges of succestive electrodes are closely spaced or contiguous. The sprocket chains 46 and hence the electrodes 52 are driven at a linear speed slightly greater than the linear rate of advance of the conveyor belt 34.

In order to deposit the sponge forming mass into the trough 13 in a uniformly flowing oriented state there is located in the trough 13 adjacent its feed end a forwardly directed hopper 56. The width of the hopper 56 is slightly less than that of the trough 13 in which it is nested and includes a rear vertical wall 57 projecting from a point above the trough base 26 to a point above the trough 13. The hopper side walls include upper rectangular sections 5S located above the trough 13 and defining with a front wall 59 and rear wall 57 a vertical feed chute 65. The lower sections 60 of the hopper side walls project forwardly of the chute 65 and include a horizontal top edge supporting atop wall 61 and lower trailing edges to which is fastened a horizontal bottoml wall 63 located above the trough base 26 and projecting forwardly of the chute 65. The upper leading edges of side walls 60 are vertical and are connected by a vertical front wall 64, the lower ends of the leading edges joining the bottom wall 63 by downwardly rearwardly inclined edges 66.

Supported between the side Wall sections 60 are a plurality of vertically spaced horizontal baiiie plates` 67 which are horizontally offset, the upper plates 67 being located at successively more forward and overlapping position. The leading side edges `68 of the plates 67 converge to tapered transverse leading edges 70 which lie along a plane parallel to the plane of the wall edges 66. Supported by the side wall sections 60 and depending from the inclined edges `66 are a plurality of depending transversely extending guide plates 69` having horizontal bottom edges lying in a plane parallel to the plane of the edges 66.

The sponge forming mass is introduced into the chute 65 flows downwardly and then forwardly along the direction of the baffles 67 and thence downwardly as guided by plates 69 Vwhere it is deposited upon the belt 34. It should be noted that the head on the sponge forming mass, its viscosity, the advancing speed of the belt 34 and the parameters of the hopper 56 are such that the mass is drawn at a slightly greater speed than its normal rate of flow through the hopper whereby to inhibit any turbulence or disturbance of the orientation of mass deposited into the trough. It should also be noted that by reason of the conguration of the bafes 67 there is a uniform retardation of the mass ow in the hopper to insure the uniform and oriented flow of the mass therethrough. The lower edges of the plate 69* serve as doctor edges to further maintain a uniform mass orientation.

As a specific example of a coagulating apparatus in accordance with the present invention the trough 13 is approximately 20 feet long, 16 inches high and 19 inches wide at the trailing end, converging uniformly to 18 inches wide at the leading end. The drums 14 and 17 are 16 inches in diameter and their axes are at the level of the trough base 26. The horizontal distance the belt travels between the upper edges of the drums 14 and 17 and the trough base is approximately 30 inches.

Considering now the `operation of the improved machine, Ia sponge lforming mass may be produced by making in accordance with any well known method a green viscose having -a high salt point, for example, in excess of 16 and a cellulose content of 8% and having -a high degree of polymerization. Specifically, between 4'0 and 50 pounds of pulp sheet of high alpha-cellulose, for example, 45 pounds are steeped in an approximately 1811/2 sodium hydroxide solution for a time sufficient to lconvent the cellulose into lalkali cellulose. The excess sodium hydroxide solution is then pressed from the resulting alkali cellulose in the conventional manner and the unaged alkali cellulose is admixed with between 15 and 27 pounds of carbon bisuliide, and the resulting mixture is tumbled in a suitable drum cellulose x-anthate is produced in accordance with the general practice. The resulting cellulose xanthate is dissolved in a weak sodium lhydroxide solution in `an amount to produce approximately 600 pounds cf viscose having an analysis of between 6% and 8% cellulose, for example, 7.6% cellulose, 5% to 7% of total alkalinity, for example, 7% and between 3.3% and 3.6% total sulphur, for example, 3.3%.

To the 600 pounds of viscose in a green unripened condition having a viscosity of approximately 200` seconds, `as measured by the fall in the viscose lfor 8 inches of a 1A inch diameter ball, lthe viscose containing suitable dyestuff, is then added Vfrom 10 to 20` pounds, for example, 15 pounds of cut fully opened flax, hemp, or other i'ber, having a fiber length of from :Vs inch to l inch, for example, 3%; inch and thorough mixing thereof is effected, preferably Iby means of a double delta blade mixing machine while maintaining 'the mass lat a ternpenature not exceeding 15 C. 'I'his initial mixing period is preferably in excess of 20 minutes, for example, 30 minutes. To the resulting mass is added between 1000 'and 250.0 pounds, for example, 1700 pounds of sodium sulphate decay-hdrate crystals having an 'average particle size in accordance the desired pore size off the iinished sponge. IFor example, van average particle size of about 10 millimeters will produce a relatively coarse pore spon-ge, whereas 1an 'average particle size of about 2 millimeters will produce a relatively tine pore sponge. ri'he mixing is then continued for approximately 10 minutes while maintaining the temperature at about C. or less to produce the sponge forming mass.

The drive motor y2,2 lis energized and lthe variable speed drives 2|1, 25 .and 43 yare adjusted so that the dru-m 14 has a peripheral speed of about 8 inches per minute, the drum 17 about 4 inches per minute and the electrodes 52 a linear rate `of advance of about 4.6 inches per minute. The sets of electrodes SI2 are connected to opposite terminals of a source of alternating current. Although it is convenient to employ y60 cycle alternating current, the use of higher frequencies oifer many advantages. The sponge forming mass is introduced into the hopper 56 and ilows into the trough 13` and advanced by the belt 34 las aforesaid. The voltage impressed electrodes 52 travel at a greater speed than and in sliding contact with the sides of the iadvancing mass raising the temperature thereof uniformly Ithroughout by reason of the resistance heating thereof. The liquid leached from the heated mass, principally a concentrated solution of sodium sulphate fis `drained by the pipes 29 `and reci'rcu-lated into the trough. Under the above conditions, where .the height of the mass in the trough was 1l inches the electrode current was Iabout 900 amperes and at a height of 12 inches the current was about 1000 iamperes. The mass does not flow rearward-ly because of its high viscosity, the advancing belt, and since the space between `the Ibelt 34 and the wall lower edge is very small and there is little more than sufficient clearance permitting the passage of the electrodes l512 between the hopper side walls and trough side walls. Each set of electrodes is at substantially a unipotential as assured by the -tracks 38 and contacting metal plates 28.

IWhen the mass reaches the discharge end of the trough 13 it is coagulated `and substantially regenerated. 'The electrodes traversing a different path are separated from the coagulated sponge at the discharge end of the conveyor belt and the sponge is discharged upon the roller table 11 from where it is transported for further processing in any desired manner 'as earlier set fort-h. The degree of current consumption and heating of the mass as well as the uniformity thereof .is facilitated and controlled by adjusting the valved conduits 29 and hence the recirculation of the hot sodium sulphate iluid in the mass. The uniformity of the heating and coagulation is further improved by the upward incline of the Idischarge run of the belt 34.

While there has been vdescribed and illustrated a preferred embodiment of the present invention it is apparent that numerous alterations, omissions and additions may be made without departing from: the spirit thereof.

What is claimed is:

l. An apparatus for the `continuous coagulation of a viscose sponge forming mass comprising a longitudinally substantially horizontally extending trough having a lead end and :a discharge end, -an endless lbelt conveyor having an upper run extending along the base of said trough, means adapted to advance said belt conveyor along said upper run Ifrom said feed end toward said discharge end, a pair of .mutually insulated sets of electrodes disposed along opposite sides of said trough, electrode advancing means adapted to advance said electrodes in the direction of advance of said belt conveyor, and means for depositing a sponge forming mass in said trough and upon said belt conveyor adjacent tothe feed end thereof.

2. An apparatus in accordance with claim 1 wherein said tro-ugh has openings formed in the wall thereof to permit the egress of fluid from said trough from between the ends thereof and .recirculating means adapted to recirculate said liuid to the top and along fthe length of said trou-gh.

3. An apparatus in accordance with claim 1 including a plurality of valved conduits communicating with said trough Ithrough `the bottom wall thereof, a plurality of spray mem-bers `disposed above and directed toward said trough land means includ-ing a pump alfording liquid communication 4between said conduits and said spray members.

4. An apparatus in accordance with claim 1 wherein said mass depositing means includes a hopper registering with said trough and having ya discharge opening disposed in said trough, said hopper being provided with a plurality of baffle plates extending along the direction of ow of said mass whereby `to effect the orientation thereof.

5. An apparatus in accordance with claim 4 wherein said baie plates extend across and parallel to the llo-w of said mass and are narrower down stream than up stream.

6. An apparatus in accordance with claim 1 wherein said mass depositing means includes a hopper having an upper vertical chute communicating with a horizontal duct, a plurality of vertically spaced horizontal baffle plates disposed in said duct, said duct having a downwardly forwardly directed discharge opening and a plurality of transverse plates depending from said discharge opening and terminating at different levels.

7. An improved apparatus in accordance with claim 1 wherein said electrode advancing means 'are adapted to yadvance said electrodes at a -grealter rate of speed than said conveyor belt.

8. An apparatus in accordance with claim l wherein the side walls of said trough converge from the trailing to the leading end thereof.

9. An apparatus for the continuous coagulation of a viscose sponge forming mass comprising a longitudinally extending trou-gh having a feed end and a discharge end, an endless belt conveyor having an upper run extending along the base of said trough, belt advancing means adapted to advance said belt conveyor along said upper run from said feed end toward said discharge end and along an upwardly inclined path adjacent to said discharge end, a pair of mutually insulated sets of electrodes disposed along opposite sides of said trough, electrode advancing means adapted to advance said electrodes along a path in the direction of advance of said belt conveyor, and means for depositing a sponge forming mass in said trough and upon said belt conveyor adjacent to the feed end thereof.

10. An apparatus in accordance with claim 9 wherein said electrodes are defined yby substantially rectangular metal plates disposed in substantially edge to edge relationship Within said trough.

11. An apparatus in accordance with claim 9 wherein said paths of advance of said electrodes are divergent relative to said conveyor belt adjacent to the discharge end thereof.

References Cited in the le of this patent UNITED STATES PATENTS Coddington May 23, Te Grotenhuis Mar. 5, Stratton Sept. 7, Wright July 26, Schulerud Ian. 8, Shealy Apr. 23, Bishop Sept. 17, Nickelson July 15, Lachiche et al. Sept. 8,

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