Apparatus for and method of sieving biocompatible adsorbent beaded polymers

Abstract

For sieving biocompatible adsorbent beaded polymeric materials, a column is formed for accommodating beads of the polymeric material, a fluid is formed into the column upwardly, a plurality of screening elements located in the column between a bottom of the column and a top of the column and spaced from one another in a vertical direction, the screening elements having openings of different sizes, so that beads of the polymeric material below a predetermined threshold are displaced by a fluid flowing upwardly and through a respect to one of the screening elements, while beads above the predetermined threshold are retained under a respective one of the screening elements, and a plurality of further fluids are supplied downwardly onto each of the screening elements so as to prevent clogging of a respective one of the screening elements and to agitate the polymeric beads in the column under a respective one of the screening elements.

Description

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an apparatus for and method of sieving biocompatible adsorbent beaded polymers.

[0003] Generally, there are two methods of manufacturing adsorbent polymer beads. The first system is jetting. This method can produce large quantities of beads in a very narrow size range. However, the equipment requires a large capital investment. The second, and more commonly used process involves a mechanical stirring apparatus, which creates axial mixing with in the vessel. The design of the mixing apparatus has a large affect on gaussian distribution of particle size obtained during a polymerization. For mechanical reasons, a portion of the polymer produced during a polymerization is usable due to its size. For example, particles less than 300 mm in size may clog the polymer beads causing unwanted back pressure within a column or device. Particles that are too large may not function well with regard to adsorptive capacity as a function of time. Therefore, it is often necessary to sieve the polymer to eliminate fine or small particles. It may also be necessary to exclude large particle.

[0004] Currently, several sieving methods are known in the industrial use. Mechanical sieving is a method whereby a screen or mesh is employed. The screen or mesh has openings that are of a size sufficient to allow particles smaller than the openings to pass through the mesh while preventing larger particles from passing through. Mechanical sieving can be conducted wet or dry.

[0005] Wet sieving employs a fluid, typically water, to assist the sieving process. An amount of polymer is placed on top of a screen. Water is then flowed over the polymer and screen. The movement of water, with gravity, down through the screen carries the particles which are sufficiently small through the sieve leaving behind particles larger than the screen or mesh openings. For example, employing a 300 mm sieve would eliminate particles from the sample smaller than 300 mm and preserve particles greater than 300 mm. This method is problematic because the mesh tends to clog. Larger particles, retained by the mesh fill up the available openings and the mesh must be continually unclogged. Shaking, vibration and other mechanical methods can be employed to unclog the mesh. However, these methods can be unreliable and may damage the polymer. Maintaining sterility in an environment such as this is also extremely challenging.

[0006] Dry sieving is accomplished in the exact same way except that gravity, or inertia, are the only forces used to transport the particles through the sieve. Dry sieving can create a great deal of static electricity that can prevent sieving from being completed. There are several methods that can be employed to eliminate or prevent the static build up. Combining the polymer with talc (a mineral) is one method. However, this method is not viable when maintaining sterility is required.

[0007] Sieving is also performed in a column filled with a fluid. This method works well for maintaining sterility and cannot clog because it does not use a mesh or screen in order to size the beads. A bed of polymer is placed in a column filled with a fluid. Depending on the density of the polymer, alternative fluids can be used such as water, alcohol, or some mixture of the two. The fluid is accelerated contra-gravity with a linear flow rate of sufficient speed to expand the polymer bed. However, the linear flow rate cannot be so greater as to cause the polymer to flow to the top of the column and out the drain mechanism. Once the bed is expanded, at a constant linear flow rate, the polymer will separate according to size. Larger, heavier beads will collect toward the lower portion of the expanded bed. Smaller particles and fines will propagate and collect toward the top of the column. Once this is accomplished, the linear flow rate can be increased sufficiently in a manner that allows the unwanted particles to enter the drain mechanism at the top of the column. As this process continues, samples of the polymer are taken at the top of the expanded bed. When a certain predetermined percentage of the beads tested are of sufficient threshold size, what remains in the column is reported “sized” above that threshold size.

[0008] Although this method works, it is a slow and inexact process. Only a relatively small amount of polymer can be processed at a given time. This limitation is a function of the size of the column and the amount of fluid required to expand the bed. It is also very time consuming and easily allows particles below the threshold size to remain in the column.

SUMMARY OF THE INVENTION

[0009] Accordingly, it is an object of the present invention to provide an apparatus for and method of sieving biocompatible adsorbent beaded polymers which avoids the disadvantages of the prior art.

[0010] In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in an apparatus for sieving biocompatible adsorbent beaded polymeric materials, comprising means forming a column for accommodating beads of the polymeric material; means for supplying a fluid into said column upwardly; a plurality of screening elements located in said column between a bottom of said column and a top of said column and spaced from one another in a vertical direction, said screening elements having openings of different sizes, so that beads of the polymeric material below a predetermined threshold are displaced by the fluid flowing upwardly and through a respect to one of said screening elements, while beads above the predetermined threshold are retained under a respective one of said screening elements; and means for supplying a plurality of further fluids downwardly onto each of said screening elements so as to prevent clogging of a respective one of said screening elements and to agitate the polymeric beads in said column under a respective one of said screening elements.

[0011] It is another feature of present invention to provide a method sieving biocompatible adsorbent beaded polymeric materials, comprising the steps of forming a column for accommodating beads of the polymeric material; supplying a fluid into said column upwardly; providing a plurality of screening elements located in said column between a bottom of said column and a top of said column and spaced from one another in a vertical direction, said screening elements having openings of different sizes, so that beads of the polymeric material below a predetermined threshold are displaced by the fluid flowing upwardly and through a respect to one of said screening elements, while beads above the predetermined threshold are retained under a respective one of said screening elements; and supplying a plurality of further fluids downwardly onto each of said screening elements so as to prevent clogging of a respective one of said screening elements and to agitate the polymeric beads in said column under a respective one of said screening elements.

[0012] When the apparatus is designed and the method is performed in accordance with the present invention, the sieving process is considerably facilitated and accelerated.

[0013] The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The single figure of the drawings is a view schematically showing an apparatus for sieving biocompatible adsorbent polymers in accordance with the present invention, operating in accordance with the inventive method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An apparatus for sieving biocompatible beaded adsorbent polymeric material has a column which is identified with reference numeral 1. The column 1 is filled with a medium, which is preferably sterile, for example with ultrapure water as identified with reference numeral 2. Beads of a biocompatible beaded adsorbent polymeric material are supplied into the column. A plurality of sieving elements 3 are arranged in the column between its bottom and its top, such that the entire path through the column is dissected several times. The sieving elements 3 can be formed as a mechanical sieve, a mesh, a screen, etc. When the sieving elements are installed in the column, the only way for a particle to pass from the bottom of the column to the top of the column is through the openings in the sieving elements. Reference numeral 7 identifies a fluid source which supplies fluid into the column from below, to fill the column and to displace the beads upwardly.

[0016] The screening elements 3 each have a plurality of openings. The openings in the different screening elements 3 have different sizes. Preferably, the size of the openings of the screening elements reduces from one screening element to the other screening element in a vertical direction upwardly. In other words, the size of the openings in the lowermost screening element is the greatest, while the size of the openings in the uppermost screening element is the smallest.

[0017] The apparatus further has a plurality of fluid supply sources which supplies a further fluid, for example water from above downwardly, in particular above each of the sieving elements, as identified with reference numerals 4. Reference numeral 5 identifies an inlet for polymeric beads for introducing the bead into the column, and reference numerals 6 identify outlets for the polymeric beads for discharging the beads after being sieved above each of the screening elements 3.

[0018] Reference numerals 8 identify means for transversely moving or rotating the fluid sources 4. Reference numerals 9 identify means for transversely moving or rotating the screening elements 3. Reference numeral 10 identifies means for transversely moving or rotating the column 1. The transversely moving or rotating means can be formed as any known means, such as for example a motor with a corresponding transmission, etc. Finally, reference numeral 11 identifies a control unit.

[0019] In operation the fluid is supplied it the column 1 upwardly by the source 7, in direction of anti-gravity, so as to move the beads of the polymeric material upwradly toward the screening elements 3. The flow rate of the fluid is sufficient to force the beads through the openings of the screening elements. Since the sizes of the openings of the screening elements 3 are different then therefore at each of the screening elements the beads below a certain threshold size pass through the openings of the corresponding screening element, while below each of the screening elements larger beads above the threshold size are retained. The beads retained under the corresponding screening elements are discharged through the outlets 6.

[0020] The sources of a further fluid, such as pressurized water identified with reference numerals 4 supply the fluid in a countercurrent to the fluid which is supplied to the bottom of the column upwardly, above each of the screening elements 3 and toward the corresponding screening element. The further fluid supplied by the source 4 can direct the further fluid downwardly through at least a part of the area of the corresponding screening area 3 which is significantly less than 100%. In this way, the fluid jet supplied by the corresponding source 4 and directed downwardly causes the bed of the polymeric beads to turn over and to be agitated, so that the openings of the corresponding screening element 3 are not clogged and the sieving process at each screening element is significantly accelerated.

[0021] Preferably, the fluid which is supplied upwardly from the bottom of the column 1 by the source 7 toward the screening elements 3 covers the entire area of the screening elements. In contrast, as explained above, the downward jet of the further fluid supplied by the sources 4 covers only a portion of the entire area, and can be constantly displaced transversely, preferably in a circular motion. This transverse displacement can be performed for example by rotating the fluid sources 4 by the means 8, so as to repeatedly cover the entire area of the corresponding screening element from above. This can be also accomplished by keeping the fluid sources 4 stationary, and instead by transversely moving or rotating the column 1 by the means 10. This can be further achieved by keeping the fluid sources 4 stationary and by transversely moving or rotating the screening elements 3 by the means 9 within the column 1.

[0022] In accordance with another feature of the present invention, the control means 11 control various steps of the inventive process in the inventive apparatus. Since the size of the openings of the different screening elements is different, therefore the control unit 11 can control or adjust at least one parameter of the further fluid supplied by the fluid sources 4, for example to adjust a pressure, a flow rate, a speed, etc. of the further fluid supplied by the corresponding fluid source 4 so as to provide an optimal unclogging of the pores of the corresponding screening element 3 and the agitation of the beads below the corresponding screening element 3. It is believed to be clear that at least one parameter can be adjusted for the screening elements 3 so that, for different screening element this parameter is different. The control unit 11 can also adjust the speed of rotation of the corresponding source 4 of the fluid supplied to the corresponding screening element, the speed of rotation of the screening element 3, and the speed of rotation of the column 1, so as to provide an optimal clogging prevention of the corresponding screening element 3 and agitation of the beads below the corresponding screening element 3, for each of the screening elements individually.

[0023] It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of methods differing from the types described above.

[0024] While the invention has been illustrated and described as embodied in apparatus for and method of sieving biocompatible adsorbent beaded polymers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

[0025] Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

[0026] What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

1. A device for sieving biocompatible adsorbent beaded polymeric materials, comprising means forming a column for accommodating beads of a polymeric material; means for supplying a fluid into said column upwardly; a plurality of screening elements located in said column between a bottom of said column and a top of said column and spaced from one another in a vertical direction, said screening elements having openings of different sizes, so that beads of the polymeric material below a predetermined threshold are displaced by the fluid flowing upwardly and through a respect to one of said screening elements, while beads above the predetermined threshold are retained under a respective one of said screening elements; and means for supplying a plurality of further fluids downwardly onto each of said screening elements so as to prevent clogging of a respective one of said screening elements and to agitate the polymeric beads in said column under a respective one of said screening elements.

2. A device as defined in claim 1, wherein said means for supplying fluid upwardly is formed so that the fluid supplied upwardly covers an entire area of all said screening elements, while said means for supplying the further fluids downwardly are formed so as to cover only a portion of the entire area of each of said screening elements.

3. A device as defined in claim 1; and further comprising means for adjusting at least one parameter of the further fluids independently from one another.

4. A device as defined in claim 3, wherein said means for adjusting at least one parameter includes means for adjusting a parameter selected from the group consisting of a pressure, a flow rate, and a speed of respective one of said further fluids.

5. A device as defined in claim 1; and further comprising means for providing a relative movement which is transverse in a vertical direction between said fluid supplied upwardly and a respective one of said further fluids supplied downwardly.

6. A device as defined in claim 5; and further comprising means for adjusting at least one parameter of the relative movement between said fluid supply downwardly and a respective one of said further fluids supplied upwardly.

7. A device as defined in claim 5, wherein said means for providing a relative movement include means for rotating said means for supplying said further fluids downwardly.

8. A device as defined in claim 5, wherein said means for providing the relative movement include means for rotating a respective one of said screening elements.

9. A method for sieving biocompatible adsorbent beaded polymeric materials, comprising the steps of forming a column for accommodating beads of the polymeric material; supplying a fluid into said column upwardly; arranging a plurality of screening elements in said column between a bottom of said column and a top of said column and spaced from one another in a vertical direction, said screening elements having openings of different sizes, so that beads of the polymeric material below a predetermined threshold are displaced by the fluid flowing upwardly and through a respect to one of said screening elements, while beads above the predetermined threshold are retained under a respective one of said screening elements; and supplying a plurality of further fluids downwardly onto each of said screening elements so as to prevent clogging of a respective one of said screening elements and to agitate the polymeric beads in said column under a respective one of said screening elements.

10. A method as defined in claim 9, wherein said supplying fluid upwardly includes supplying the liquid so that the fluid supplied upwardly covers an entire area of all said screening elements, while said supplying the further fluids downwardly includes supplying the further liquids so as to cover only a portion of the entire area of each of said screening elements.

11. A method as defined in claim 9; and further comprising adjusting at least one parameter of the further fluids independently from one another.

12. A method as defined in claim 11, wherein said adjusting includes adjusting at least one parameter includes adjusting a parameter selected from the group consisting of a pressure, a flow rate, and a speed of respective one of said further fluids.

13. A method as defined in claim 9; and further comprising providing a relative movement which is transverse in a vertical direction between said fluid supplied upwardly and a respective one of said further fluids supplied downwardly.

14. A method as defined in claim 13; and further comprising adjusting at least one parameter of the relative movement between said fluid supply downwardly and a respective one of said further fluids supplied upwardly.

15. A method as defined in claim 13, wherein said means for providing a relative movement includes rotating said means for supplying said further fluids downwardly.

16. A method as defined in claim 13, wherein said providing the relative movement includes rotating a respective one of said screening elements.