CA2227716A1 - Filter device - Google Patents
Filter device Download PDFInfo
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- CA2227716A1 CA2227716A1 CA002227716A CA2227716A CA2227716A1 CA 2227716 A1 CA2227716 A1 CA 2227716A1 CA 002227716 A CA002227716 A CA 002227716A CA 2227716 A CA2227716 A CA 2227716A CA 2227716 A1 CA2227716 A1 CA 2227716A1
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- Prior art keywords
- filter
- adsorptive
- adsorptive material
- filter according
- layer
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/68—Halogens or halogen compounds
- B01D53/685—Halogens or halogen compounds by treating the gases with solids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0407—Constructional details of adsorbing systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/72—Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8678—Removing components of undefined structure
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/14—Reducing influence of physical parameters, e.g. temperature change, moisture, dust
- G11B33/1446—Reducing contamination, e.g. by dust, debris
- G11B33/146—Reducing contamination, e.g. by dust, debris constructional details of filters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
- B01D2253/10—Inorganic adsorbents
- B01D2253/102—Carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2259/00—Type of treatment
- B01D2259/40—Further details for adsorption processes and devices
- B01D2259/414—Further details for adsorption processes and devices using different types of adsorbents
- B01D2259/4141—Further details for adsorption processes and devices using different types of adsorbents within a single bed
- B01D2259/4145—Further details for adsorption processes and devices using different types of adsorbents within a single bed arranged in series
- B01D2259/4146—Contiguous multilayered adsorbents
Abstract
A filter device (10) filters contaminants from air for magnetic disk drive systems. The filter has layers of permeable fabric material allowing flow through the filter. An adsorptive slurry (18) is deposited in a discreet pattern onto one layer (16) with a cover layer mounted over the adsorptive deposit. The slurry retains a high adsorptive material surface area for improved adsorption of contaminants. The slurry is placed onto the base material using a screening or other similar application method.
Description
W096/35499 PCT~S96/06073 FILTER DEVICE
BAC~GROUND OF TXE lNv~NlION
1. Field of the Invention The present invention relates to a filter device, and in particular to a filter device which is utilized with computer disk drive systems.
BAC~GROUND OF TXE lNv~NlION
1. Field of the Invention The present invention relates to a filter device, and in particular to a filter device which is utilized with computer disk drive systems.
2. ~esc~i~tion of the Prior Art Magnetic disk drives which are used in high numbers throughout the computer industry require a clean environment to operate. Cont~m;n~nts can lead to corrosion and other problems with the components. It has been found that even ambient levels of urban pollution can lead to corrosion which will also lead to failure of the disk drives. To overcome these problems, the systems may be equipped with filter devices which remove particles and corrosive and condensable vaporous cont~min~nts from the system air. Filter devices utilized include breathers, recirculation filters and static pouches.
Hard disk files normally need to be vented to the atmosphere of the surrounding environment to prevent excess pressure building up in the head disk enclosure. During operation, files will heat up and air will ~low out o~ the head disk enclosure. The thermal cycling of the assembly will result in air flow in and out of the enclosure. Organic vapors con~nce on the surface of the disk causing the head to stick to the surface of the disk (stiction). The new thin film technology utilized in the higher density disks and the high strength to weight metals utilized in the disk file assembly are very susceptible to corrosion as well. Chemical or adsorptive breathers have been developed to provide for removal of the vaporous and gaseous cont~min~nts in addition to removal of particulate cont~min~nts~
As magnetic d_ives become more and more compact, smalle- components are required. Therefore, the size or the Silters and especially the _hickness o the filters needs to become more and more compact while providing greate-W 096/3S499 PCTrUS96/06073 protection. The decreased size and the air flow generated by the high speed mechanisms can cause a pressure differential to occur across a breather or recirculation filter.
Therefore, it is necessary that the filter device provide adequate flow through the filter to prevent great pressure differential within the drive. If a large pressure difference does develop across a filter, unfiltered leaks will occur within seals, bearings or other moving parts.
With recirculation filters, a high differential pressure increases the clean up time of the drive during initial burn in and spin up.
An example of a prior filter device is represented by U.S. Patent 4,657,570 showing an Air Filter Device, assigned to Donaldson ~o~mp~ny~ Inc., the assignee of the present invention. Although the filter device provides filtering of air in magnetic disk drive systems, the activated carbon portion for adsorption of corrosive gases and potential con~oncates must be cut and the construction is relatively complicated. Therefore, the device has higher manufacturing costs and requires greater assembly time. In addition, the filtering portion needs to be cut, thereby leading to possible cont~m;n~tion o~ the filtering device during assembly. In the extremely clean conditions which are needed for the filtering devices, cutting of portions of the filter media can cause cont~m~n~tion and ~uality control problems.
It can be seen then that new and improved filter devices ~or disk drive systems are needed. Such devices should provide for filtering air and removing gaseous cont~m~n~nts from contaminating the disk drive system. In addition, ~ilter devices should have a construction whicr provides ~or a very narrow profile with ade~uate clearance in the disk drive system. Such a device should be inexpensive and easy to manu~acture without con~amination during the assembly process. The present invention addresses these as well as other problems associated with filter devices for disk drive systems.
SU~ RY OF THE lNV~:NllON
5The present invention is directed to a family of filter devices such as are commonly used with magnetic disk drive systems.
According to the present invention, the filter device utilizes a base layer having an adsorptive slurry deposited onto the base in a discreet pattern. The adsorptive slurry is a dispersion of adsorptive material such as an activated carbon or catalytic material for removal of cont~min~nts from the air for the disk drive system. A cover layer is applied over the adsorptive slurry deposit to provide for an area around the deposit for sealing.
The adsorptive slurry can contain other additives for removing various types of cont~min~nts~ However, in a preferred embodiment, the slurry does not contain a binder or latex to hold the adsorptive material together. Elimination of the commonly used binder material provides m~i~nm surface area of the adsorptive material for adsorption of the cont~m~n~nts.
In a preferred method of making the filter device, a rotary screen type device is utilized to apply the 2S adsorptive slurry. In one preferred method, the slurry is deposited onto a rotary screen which engages the base layer.
The cohesive strength of the slurry provides for the slurry transferring from the screen to the base layer in a discreet pattern. It can be appreciated that some drying may be required prior to applying the cover layer to help maintain the shape of the deposited adsorptive component. Individual filters are then cut from the resulting composite and the edges sealed. An adhesive portion may be applied to one side of the filter device to provide for mounting to the disk~5 drive system. Various types of filter and support materials W 096/3S499 PCTrUS96/06073 can be combined to support and retain the adsorptive deposit which have the properties for the intended use and application.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereo~. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a ~urther part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWIN~S
In the drawings, wherein like reference letters and numerals designate corresponding elements throughout the several views:
Figure 1 shows a top plan view of a filter device according to the principles o~ the present invention;
Figure 2 shows a side elevational view of the filter device shown in Figure 1;
Figure 3 shows a bottom plan view o~ the filter device shown in Figure l;
Figure 4 shows an exploded side elevational view o~ the breather filter device shown in Figure 1;
Figure 5 shows a ~low chart of the method o~ making the filter device shown in Figure 1;
Figure 6 shows a top plan view of a sheet of material with the adsorptive layer added during manu~acturing of the filter device shown in Figure 1;
Figure 7 shows a diagrammatic view of the screenins device utilized in making the ~ilter device shown in Figure 1 ;
W O 96/3S499 PCTrUS96/06073 Figure 8 shows an exploded side elevational view of a second embodiment of a filter device according to the principles of the present inventioni and Figure 9 shows an exploded side elevational view of a third embodiment o~ a filter device according to the principles of the present invention.
DETAI~D DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to Figure 1, there is shown a filter device, generally designated 10.
In a first preferred embodiment, filter device 10 is a breather ~ilter. The ~ilter device 10 includes an active filtering media area 12 surrounded by an outer sealed portion 14.
As shown in Figure 2, the filter device 10 has an extremely narrow profile. Referring to Figure 3, the breather filter device 10 includes an ~nn~ r adhesive layer 28 a~ixed thereto. The adhesive layer 28 affixes to the filter device and includes a second adhesive side with a peelable paper layer which can be removed for affixing the filter to the appropriate position on the housing for a magnetic disk drive or other apparatus. Although, the filter device 10 is shown as circular, it can be appreciated that other shapes, such as rectangles, ovals or other common shapes may also be used.
Referring now to Figure 4, there is shown an exploded view of the ~ilter device 10. The filter device 10 includes a number of layers fused or otherwise joined to contain an adsorptive deposit 18 in the active filter media area 12. The adsorptive deposit 18 is normally placed in a discreet pattern on a base material 16 which in a first embodiment includes three layers combined to form the base.
In the preferred embodiment, the adsorptive deposit 18 is an W O 96/35499 PCTrUS96/06073 adsorptive slurry which is deposited with a screen printing type process, as explained hereinafter. In the embodiment shown, the composite base 16 includes a support layer 20 receiving a HEPA or ULPA efficiency membrane 22. Mounted on the membrane layer 22 is an adsorptive material holding layer 24 which receives the adsorptive deposit 18. In the preferred embodiment, the three layers 20, 22 and 24 are joined together in a base sheet 16 prior to deposition of the adsorptive layer 18. It can be appreciated that the discreet deposits of the adsorptive layer 18 may be put on the base sheet 16 in multiple rows, for higher production volume, as shown in Figure 6. Covering the adsorptive deposit 18 is a cover layer 26 which extends beyond the edges of the adsorptive layer to seal the adsorptive material 18 within lS the filter device 10. In the preferred embodiment, the support layer 20 is a polymeric open screen or woven material, while the adsorptive material holding layer 24 and cover layer 26 are permeable fabrics, either woven or non-woven materials. The doubled sided adhesive layer 28 is applied to the cover layer. The adhesive layer 28 is annular and preferably has a smaller diameter opening than the diameter of the adsorptive layer 18.
Referring to Figure 5, steps for making the filter device are detailed. As explained above, the three layers 20, 22 and 24 are combined to form a base 16. The adsorptive materials 18 are prepared as a slurry for application to the base 16 in a discreet pattern. The slurry is then deposited on the base 16 through a screening or other transfer process.
Following drying and application of adhesive to the base and adsorptive layers of the filter for attaching the cover layer 26 to the composite base 16. Individual filter devices 10 are cut from the resulting composite, as shown in Figure 6.
The edges are then welded, thereby sealing the adsorptive material 18 within the filter 10. The adhesive rings are W 09613S499 PCTrUS96/06073 then applied and the breather ~ilter device lo is ready ~or use.
Referring to Figure 7, the adsorptive layer application steps are shown. In a first method, the adsorptive layer 18 is applied on a rotary type screening apparatus 36. The screening apparatus 36 includes a cylinder 38 a~d a complementary opposed roller 40. The cylinder 38 includes a screen portion 42 positioned along its periphery.
A pump 44 delivers the adsorptive slurry onto the screen 42.
The excess is then removed and the screen 42 rotates with the cylinder 38 to engage the base material 16. The adsorptive material may be printed onto either a stationary sheet or a moving web with the rotary screen printing device 36. A
desired deposit pattern is created in the screen 42 by any of the processes well known in the industry, such as by using a mass woven screen or acid etching a metal screen. The adsorptive slurry is applied to the back of the screen 42 and pressed into the openings of the screen 42 by a rubber blade, roller or similar device.
As the rotary screen engages the base layer 16, the cohesive strength of the adsorptive layer is such that when the screen 42 is pressed onto the filter base 16, the adsorptive material from the screen 42 transfers to the base 16. The screen mesh and thickness must be sized ~or the type o~ adsorptive material 18 and the amount of material which is to be deposited. In the case of an activated carbon adsorptive slurry 18, the weight of the adsorptive layer is 20 to 100 grams per square meter. For example, in a one inch filter, the deposit will have a mass of anywhere between 4 to 20 milligrams per device 10. It can be appreciated that the weight of the adsorptive layer 18 will depend on the density o~ the adsorptive material which is deposited.
Following deposition of the adsorptive layer 18, the slurry will be wet and may require drying. Therefore, the base 16 having the slurry deposited thereon may be passed W 096/3S499 PCTrUS96106073 through a drying apparatus 46. In addition, following drying, an adhesive sprayer 48 may apply adhesive for applying the cover layer 26. In the preferred embodiment, the edges are sealed with an ultrasonic sealing device 50.
The adsorptive slurry 18 may use several types of active materials including activated carbon, activated alumina, molecular sieves, ion exchange resins or other functional resins and polymers, diatomaceous earths, silica or clays. In addition, the adsorptive materials may be impregnated with other chemicals for selective adsorption.
These impregnates include inorganic materials which can be impregnated using either an aqueous or organic solution. A
specific choice of the impregnating solution depends on the intended use and application. For example, if acidic ash such as sulphur oxide, or nitrogen oxide, hydrogen sulfide, hydrochloric acid and sulphur based acids are being removed, the carbon can be impregnated with water soluble carbonate, bisulfite, sulfate or hydroxide salts. In addition, low molecular weight or polymeric ~mi nes can be used for removal of acid gases and acidic organic vapors such as carboxylic acids, alcohols, and phenols. Organic and inorganic halides such as potassium iodide can be impregnated into the carbon for removal of basic vapors such as N-methypyrrolidone, and other organic ~mi nes. The slurry may also be impregnated with sulfate salts for removing ammonia and other low molecular weight amines. If the area is contaminated with aldehydes and ketones, such as formaldehyde and methyl ethyl ketone, the carbon can be impregnated with 2,4 dinitrophenylhydrazine. Catalytic materials may also be added such as copper or nickel, or oxides of manganese, copper or nickel.
The slurry may also have a viscosity modifier, resin or latex added. A viscosity modifier is preferably used to prevent filming of the adsorptive materials. In a preferred embodiment, the slurry does not contain a latex or _ _ _ W O 96/35499 PCT~US96/06073 binder to hold the adsorptive material together, thereby providing m~ mllm adsorptive material surface area for adsorption of the material. In a preferred embodiment, the slurry loses very little of its adsorptive surface area. A
preferred embodiment of the slurry will retain more than 80 of the sur~ace area capacity of the active carbon.
Referring now to Figure 6, there is shown a large sheet of base material 16 having the adsorptive deposits 18 placed thereon. It can be appreciated that the method of the present invention provides a ~ast method of producing filter devices 10 in large quantities without contamination due to cutting the carbon materials as was done in prior adsorptive devices.
It can be appreciated that the layers of the filter device lO may be any type of woven or non-woven materials that are sufficiently tight to contain the adsorptive deposit 18. The layers can be a single or multiple ply, dep~n~i ng on the desired properties of the composite. It has been found that particularly useful are fabrics which have appropriate surface densities for the deposition of the adsorptive or catalytic layer. It should be noted that one o~ the sides of the composite should possess sufficient void volume into which the adsorptive layer can be deposited to maintain the shape of the adsorptive or catalytic layer when nipped between the rollers to ensure contact of the adhesive and the ~abric layers.
An example of one preferred embodiment of the filter device includes an adsorptive slurry having a composition of 7 grams o~ xanthum gum which is wetted with isopropyl alcohol. This is mixed with 20 grams of potassium carbonate and 653 grams of water. 320 grams of PCB-G
activated carbon, which can be obtained from Calgon Corporation, is added to the thickened solution. Following mixture of the solution, the slurry is ready ~or application.
The adsorptive slurry has the following adsorption capacity and surface area characteristlcs.
Table 1 Typical Equilibrium Adsorption Capacity Toluene 4.4 mgs H2S 3.4 mgs Cl2 8.7 mgs HCl 1.6 mgs NOX 4.0 mgs Table 2 Brunauer Emmett Teller ~BET) Surface Area PCB-G Carbon 968 m2/gms Slurry 841 m2/gms In the embodiment described, the slurry is pumped to the interior of the rotary screen with a repetitive circular patter of .7 ln~hes. The deposition of 13 milligrams + 4 milligrams dry weight of slurry is printed on either a base of polyethylene or similar hydrophobic or non-wicking web having a Frazier air permeability of at least 4 cubic feet per minute per square foot at one-half inch water pressure drop, as measured on a Frazier permeability tester.
In addition, other permeable non-woven materials, ~uch as a spun bonded polyester non-woven which is laminated to a membrane, may be used. A fine screen is typically used for proper distribution of PCB-G activated carbon. The resulting filter device 10 will typically have a one inch diameter with the adsorptive capacity as stated above.
Many prior art ~ilters have low Frazier permeabilities, in the neighborhood of .1 cubic ~eet per minute per square foot, which causes a large pressure drop across the filter. The permeability of the filters lo o~ the present invention are much higher, typically having Frazier W O 96/35499 PCTrUS96/06073 permeabilities in the range of .3 to .57 cubic ~eet per minute per square ~oot. Therelore, the present invention experiences a much smaller pressure drop and avoids the problems o~ the prior art, while maintaining high adsorptive capacity.
Re~erring now to Figure 8, there is shown a second embodiment o~ the ~ilter device showing an adsorbent pouch con~iguration, generally designated lOA. The absorbent pouch lOA is mounted onto an interior sur~ace of the magnetic disk drive system or other system to generally ~ilter cont~m;n~nts and remove corrosive elements. In the absorbent pouch filter lOA, an adsorptive deposit layer 18 is placed on a base layer 22 which is preferably a hydrophobic permeable membrane. An adhesive layer 28 is applied over the adsorptive layer 18.
The adhesive layer 28 and the membrane layer 22 seal around and retain the adsorptive layer 18. The adhesive layer 28 a~ixes to an interior of the magnetic disk drive or other system by r e.,l~ving a peelable paper layer. As the air circulates throughout the interior o~ the magnetic disk drive or other system, the adsorbent pouch ~ilter lOA removes cont~min~nts.
Re~erring now to Figure 9, there is shown a third embodiment of a ~ilter device according to the principles o~
the present invention, generally designated lOB. The filter device lOB is a recirculation type ~ilter ~or ~iltering the air as it is recirculated through the magnetic disk drive or other system. The recirculation ~ilter lOB includes an adsorptive layer 18. The adsorptive slurry 18 is deposited onto a base layer 34 which is similar to the base layer 16 ~or the breather ~ilter device shown in Figure 4. However, ~or a recirculation ~ilter lOB, a pair o~ base layers 34 sandwich the adsorptive layer 18. In addition, cover layers 32 are attached over the base layers 34. The cover layers 32 may be woven polyester or other material which provides satis~actory permeability. It can be appreciated that with W 096/3S499 PCT~US96106073 this arrangement, airflow can pass through the recirculatian filter lOB in either direction without a pressure build up on either side.
It can be appreciated that the various embodiments of the filter including breather filter 10, adsorbent pouch filter lOA and recirculation filter lOB may be combined in various combinations ~or removal of cont~m;n~nts or used individually. For example, the breather filter may be used with an adsorbent pouch and/or recirculation filter.
~ikewise, the others may be combined for multiple filtering configurations dep~n~, ng on the filtering needs of the system.
It is to be understood, however, that even though numerous characteristics and advantages o~ the present invention have been set forth in the foregoing description, together with details o~ the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general m~n ~ ng of the terms in which the appended claims are expressed.
Hard disk files normally need to be vented to the atmosphere of the surrounding environment to prevent excess pressure building up in the head disk enclosure. During operation, files will heat up and air will ~low out o~ the head disk enclosure. The thermal cycling of the assembly will result in air flow in and out of the enclosure. Organic vapors con~nce on the surface of the disk causing the head to stick to the surface of the disk (stiction). The new thin film technology utilized in the higher density disks and the high strength to weight metals utilized in the disk file assembly are very susceptible to corrosion as well. Chemical or adsorptive breathers have been developed to provide for removal of the vaporous and gaseous cont~min~nts in addition to removal of particulate cont~min~nts~
As magnetic d_ives become more and more compact, smalle- components are required. Therefore, the size or the Silters and especially the _hickness o the filters needs to become more and more compact while providing greate-W 096/3S499 PCTrUS96/06073 protection. The decreased size and the air flow generated by the high speed mechanisms can cause a pressure differential to occur across a breather or recirculation filter.
Therefore, it is necessary that the filter device provide adequate flow through the filter to prevent great pressure differential within the drive. If a large pressure difference does develop across a filter, unfiltered leaks will occur within seals, bearings or other moving parts.
With recirculation filters, a high differential pressure increases the clean up time of the drive during initial burn in and spin up.
An example of a prior filter device is represented by U.S. Patent 4,657,570 showing an Air Filter Device, assigned to Donaldson ~o~mp~ny~ Inc., the assignee of the present invention. Although the filter device provides filtering of air in magnetic disk drive systems, the activated carbon portion for adsorption of corrosive gases and potential con~oncates must be cut and the construction is relatively complicated. Therefore, the device has higher manufacturing costs and requires greater assembly time. In addition, the filtering portion needs to be cut, thereby leading to possible cont~m;n~tion o~ the filtering device during assembly. In the extremely clean conditions which are needed for the filtering devices, cutting of portions of the filter media can cause cont~m~n~tion and ~uality control problems.
It can be seen then that new and improved filter devices ~or disk drive systems are needed. Such devices should provide for filtering air and removing gaseous cont~m~n~nts from contaminating the disk drive system. In addition, ~ilter devices should have a construction whicr provides ~or a very narrow profile with ade~uate clearance in the disk drive system. Such a device should be inexpensive and easy to manu~acture without con~amination during the assembly process. The present invention addresses these as well as other problems associated with filter devices for disk drive systems.
SU~ RY OF THE lNV~:NllON
5The present invention is directed to a family of filter devices such as are commonly used with magnetic disk drive systems.
According to the present invention, the filter device utilizes a base layer having an adsorptive slurry deposited onto the base in a discreet pattern. The adsorptive slurry is a dispersion of adsorptive material such as an activated carbon or catalytic material for removal of cont~min~nts from the air for the disk drive system. A cover layer is applied over the adsorptive slurry deposit to provide for an area around the deposit for sealing.
The adsorptive slurry can contain other additives for removing various types of cont~min~nts~ However, in a preferred embodiment, the slurry does not contain a binder or latex to hold the adsorptive material together. Elimination of the commonly used binder material provides m~i~nm surface area of the adsorptive material for adsorption of the cont~m~n~nts.
In a preferred method of making the filter device, a rotary screen type device is utilized to apply the 2S adsorptive slurry. In one preferred method, the slurry is deposited onto a rotary screen which engages the base layer.
The cohesive strength of the slurry provides for the slurry transferring from the screen to the base layer in a discreet pattern. It can be appreciated that some drying may be required prior to applying the cover layer to help maintain the shape of the deposited adsorptive component. Individual filters are then cut from the resulting composite and the edges sealed. An adhesive portion may be applied to one side of the filter device to provide for mounting to the disk~5 drive system. Various types of filter and support materials W 096/3S499 PCTrUS96/06073 can be combined to support and retain the adsorptive deposit which have the properties for the intended use and application.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereo~. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a ~urther part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWIN~S
In the drawings, wherein like reference letters and numerals designate corresponding elements throughout the several views:
Figure 1 shows a top plan view of a filter device according to the principles o~ the present invention;
Figure 2 shows a side elevational view of the filter device shown in Figure 1;
Figure 3 shows a bottom plan view o~ the filter device shown in Figure l;
Figure 4 shows an exploded side elevational view o~ the breather filter device shown in Figure 1;
Figure 5 shows a ~low chart of the method o~ making the filter device shown in Figure 1;
Figure 6 shows a top plan view of a sheet of material with the adsorptive layer added during manu~acturing of the filter device shown in Figure 1;
Figure 7 shows a diagrammatic view of the screenins device utilized in making the ~ilter device shown in Figure 1 ;
W O 96/3S499 PCTrUS96/06073 Figure 8 shows an exploded side elevational view of a second embodiment of a filter device according to the principles of the present inventioni and Figure 9 shows an exploded side elevational view of a third embodiment o~ a filter device according to the principles of the present invention.
DETAI~D DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to Figure 1, there is shown a filter device, generally designated 10.
In a first preferred embodiment, filter device 10 is a breather ~ilter. The ~ilter device 10 includes an active filtering media area 12 surrounded by an outer sealed portion 14.
As shown in Figure 2, the filter device 10 has an extremely narrow profile. Referring to Figure 3, the breather filter device 10 includes an ~nn~ r adhesive layer 28 a~ixed thereto. The adhesive layer 28 affixes to the filter device and includes a second adhesive side with a peelable paper layer which can be removed for affixing the filter to the appropriate position on the housing for a magnetic disk drive or other apparatus. Although, the filter device 10 is shown as circular, it can be appreciated that other shapes, such as rectangles, ovals or other common shapes may also be used.
Referring now to Figure 4, there is shown an exploded view of the ~ilter device 10. The filter device 10 includes a number of layers fused or otherwise joined to contain an adsorptive deposit 18 in the active filter media area 12. The adsorptive deposit 18 is normally placed in a discreet pattern on a base material 16 which in a first embodiment includes three layers combined to form the base.
In the preferred embodiment, the adsorptive deposit 18 is an W O 96/35499 PCTrUS96/06073 adsorptive slurry which is deposited with a screen printing type process, as explained hereinafter. In the embodiment shown, the composite base 16 includes a support layer 20 receiving a HEPA or ULPA efficiency membrane 22. Mounted on the membrane layer 22 is an adsorptive material holding layer 24 which receives the adsorptive deposit 18. In the preferred embodiment, the three layers 20, 22 and 24 are joined together in a base sheet 16 prior to deposition of the adsorptive layer 18. It can be appreciated that the discreet deposits of the adsorptive layer 18 may be put on the base sheet 16 in multiple rows, for higher production volume, as shown in Figure 6. Covering the adsorptive deposit 18 is a cover layer 26 which extends beyond the edges of the adsorptive layer to seal the adsorptive material 18 within lS the filter device 10. In the preferred embodiment, the support layer 20 is a polymeric open screen or woven material, while the adsorptive material holding layer 24 and cover layer 26 are permeable fabrics, either woven or non-woven materials. The doubled sided adhesive layer 28 is applied to the cover layer. The adhesive layer 28 is annular and preferably has a smaller diameter opening than the diameter of the adsorptive layer 18.
Referring to Figure 5, steps for making the filter device are detailed. As explained above, the three layers 20, 22 and 24 are combined to form a base 16. The adsorptive materials 18 are prepared as a slurry for application to the base 16 in a discreet pattern. The slurry is then deposited on the base 16 through a screening or other transfer process.
Following drying and application of adhesive to the base and adsorptive layers of the filter for attaching the cover layer 26 to the composite base 16. Individual filter devices 10 are cut from the resulting composite, as shown in Figure 6.
The edges are then welded, thereby sealing the adsorptive material 18 within the filter 10. The adhesive rings are W 09613S499 PCTrUS96/06073 then applied and the breather ~ilter device lo is ready ~or use.
Referring to Figure 7, the adsorptive layer application steps are shown. In a first method, the adsorptive layer 18 is applied on a rotary type screening apparatus 36. The screening apparatus 36 includes a cylinder 38 a~d a complementary opposed roller 40. The cylinder 38 includes a screen portion 42 positioned along its periphery.
A pump 44 delivers the adsorptive slurry onto the screen 42.
The excess is then removed and the screen 42 rotates with the cylinder 38 to engage the base material 16. The adsorptive material may be printed onto either a stationary sheet or a moving web with the rotary screen printing device 36. A
desired deposit pattern is created in the screen 42 by any of the processes well known in the industry, such as by using a mass woven screen or acid etching a metal screen. The adsorptive slurry is applied to the back of the screen 42 and pressed into the openings of the screen 42 by a rubber blade, roller or similar device.
As the rotary screen engages the base layer 16, the cohesive strength of the adsorptive layer is such that when the screen 42 is pressed onto the filter base 16, the adsorptive material from the screen 42 transfers to the base 16. The screen mesh and thickness must be sized ~or the type o~ adsorptive material 18 and the amount of material which is to be deposited. In the case of an activated carbon adsorptive slurry 18, the weight of the adsorptive layer is 20 to 100 grams per square meter. For example, in a one inch filter, the deposit will have a mass of anywhere between 4 to 20 milligrams per device 10. It can be appreciated that the weight of the adsorptive layer 18 will depend on the density o~ the adsorptive material which is deposited.
Following deposition of the adsorptive layer 18, the slurry will be wet and may require drying. Therefore, the base 16 having the slurry deposited thereon may be passed W 096/3S499 PCTrUS96106073 through a drying apparatus 46. In addition, following drying, an adhesive sprayer 48 may apply adhesive for applying the cover layer 26. In the preferred embodiment, the edges are sealed with an ultrasonic sealing device 50.
The adsorptive slurry 18 may use several types of active materials including activated carbon, activated alumina, molecular sieves, ion exchange resins or other functional resins and polymers, diatomaceous earths, silica or clays. In addition, the adsorptive materials may be impregnated with other chemicals for selective adsorption.
These impregnates include inorganic materials which can be impregnated using either an aqueous or organic solution. A
specific choice of the impregnating solution depends on the intended use and application. For example, if acidic ash such as sulphur oxide, or nitrogen oxide, hydrogen sulfide, hydrochloric acid and sulphur based acids are being removed, the carbon can be impregnated with water soluble carbonate, bisulfite, sulfate or hydroxide salts. In addition, low molecular weight or polymeric ~mi nes can be used for removal of acid gases and acidic organic vapors such as carboxylic acids, alcohols, and phenols. Organic and inorganic halides such as potassium iodide can be impregnated into the carbon for removal of basic vapors such as N-methypyrrolidone, and other organic ~mi nes. The slurry may also be impregnated with sulfate salts for removing ammonia and other low molecular weight amines. If the area is contaminated with aldehydes and ketones, such as formaldehyde and methyl ethyl ketone, the carbon can be impregnated with 2,4 dinitrophenylhydrazine. Catalytic materials may also be added such as copper or nickel, or oxides of manganese, copper or nickel.
The slurry may also have a viscosity modifier, resin or latex added. A viscosity modifier is preferably used to prevent filming of the adsorptive materials. In a preferred embodiment, the slurry does not contain a latex or _ _ _ W O 96/35499 PCT~US96/06073 binder to hold the adsorptive material together, thereby providing m~ mllm adsorptive material surface area for adsorption of the material. In a preferred embodiment, the slurry loses very little of its adsorptive surface area. A
preferred embodiment of the slurry will retain more than 80 of the sur~ace area capacity of the active carbon.
Referring now to Figure 6, there is shown a large sheet of base material 16 having the adsorptive deposits 18 placed thereon. It can be appreciated that the method of the present invention provides a ~ast method of producing filter devices 10 in large quantities without contamination due to cutting the carbon materials as was done in prior adsorptive devices.
It can be appreciated that the layers of the filter device lO may be any type of woven or non-woven materials that are sufficiently tight to contain the adsorptive deposit 18. The layers can be a single or multiple ply, dep~n~i ng on the desired properties of the composite. It has been found that particularly useful are fabrics which have appropriate surface densities for the deposition of the adsorptive or catalytic layer. It should be noted that one o~ the sides of the composite should possess sufficient void volume into which the adsorptive layer can be deposited to maintain the shape of the adsorptive or catalytic layer when nipped between the rollers to ensure contact of the adhesive and the ~abric layers.
An example of one preferred embodiment of the filter device includes an adsorptive slurry having a composition of 7 grams o~ xanthum gum which is wetted with isopropyl alcohol. This is mixed with 20 grams of potassium carbonate and 653 grams of water. 320 grams of PCB-G
activated carbon, which can be obtained from Calgon Corporation, is added to the thickened solution. Following mixture of the solution, the slurry is ready ~or application.
The adsorptive slurry has the following adsorption capacity and surface area characteristlcs.
Table 1 Typical Equilibrium Adsorption Capacity Toluene 4.4 mgs H2S 3.4 mgs Cl2 8.7 mgs HCl 1.6 mgs NOX 4.0 mgs Table 2 Brunauer Emmett Teller ~BET) Surface Area PCB-G Carbon 968 m2/gms Slurry 841 m2/gms In the embodiment described, the slurry is pumped to the interior of the rotary screen with a repetitive circular patter of .7 ln~hes. The deposition of 13 milligrams + 4 milligrams dry weight of slurry is printed on either a base of polyethylene or similar hydrophobic or non-wicking web having a Frazier air permeability of at least 4 cubic feet per minute per square foot at one-half inch water pressure drop, as measured on a Frazier permeability tester.
In addition, other permeable non-woven materials, ~uch as a spun bonded polyester non-woven which is laminated to a membrane, may be used. A fine screen is typically used for proper distribution of PCB-G activated carbon. The resulting filter device 10 will typically have a one inch diameter with the adsorptive capacity as stated above.
Many prior art ~ilters have low Frazier permeabilities, in the neighborhood of .1 cubic ~eet per minute per square foot, which causes a large pressure drop across the filter. The permeability of the filters lo o~ the present invention are much higher, typically having Frazier W O 96/35499 PCTrUS96/06073 permeabilities in the range of .3 to .57 cubic ~eet per minute per square ~oot. Therelore, the present invention experiences a much smaller pressure drop and avoids the problems o~ the prior art, while maintaining high adsorptive capacity.
Re~erring now to Figure 8, there is shown a second embodiment o~ the ~ilter device showing an adsorbent pouch con~iguration, generally designated lOA. The absorbent pouch lOA is mounted onto an interior sur~ace of the magnetic disk drive system or other system to generally ~ilter cont~m;n~nts and remove corrosive elements. In the absorbent pouch filter lOA, an adsorptive deposit layer 18 is placed on a base layer 22 which is preferably a hydrophobic permeable membrane. An adhesive layer 28 is applied over the adsorptive layer 18.
The adhesive layer 28 and the membrane layer 22 seal around and retain the adsorptive layer 18. The adhesive layer 28 a~ixes to an interior of the magnetic disk drive or other system by r e.,l~ving a peelable paper layer. As the air circulates throughout the interior o~ the magnetic disk drive or other system, the adsorbent pouch ~ilter lOA removes cont~min~nts.
Re~erring now to Figure 9, there is shown a third embodiment of a ~ilter device according to the principles o~
the present invention, generally designated lOB. The filter device lOB is a recirculation type ~ilter ~or ~iltering the air as it is recirculated through the magnetic disk drive or other system. The recirculation ~ilter lOB includes an adsorptive layer 18. The adsorptive slurry 18 is deposited onto a base layer 34 which is similar to the base layer 16 ~or the breather ~ilter device shown in Figure 4. However, ~or a recirculation ~ilter lOB, a pair o~ base layers 34 sandwich the adsorptive layer 18. In addition, cover layers 32 are attached over the base layers 34. The cover layers 32 may be woven polyester or other material which provides satis~actory permeability. It can be appreciated that with W 096/3S499 PCT~US96106073 this arrangement, airflow can pass through the recirculatian filter lOB in either direction without a pressure build up on either side.
It can be appreciated that the various embodiments of the filter including breather filter 10, adsorbent pouch filter lOA and recirculation filter lOB may be combined in various combinations ~or removal of cont~m;n~nts or used individually. For example, the breather filter may be used with an adsorbent pouch and/or recirculation filter.
~ikewise, the others may be combined for multiple filtering configurations dep~n~, ng on the filtering needs of the system.
It is to be understood, however, that even though numerous characteristics and advantages o~ the present invention have been set forth in the foregoing description, together with details o~ the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general m~n ~ ng of the terms in which the appended claims are expressed.
Claims (28)
1. A filter for use in a disk drive system, comprising:
a base layer having an adsorptive material receiving surface and an exterior surface;
an adsorptive layer comprising an adsorptive material deposited on the adsorptive material receiving surface of said base layer in a discrete pattern to form an active-filtering and adsorbing media area; and a cover layer comprising a permeable fabric mounted to said base layer and enclosing the adsorptive material, wherein the filter has a Frazier permeability of at least 0.3 cubic feet per minute per square foot at one-half inch water pressure drop, wherein the filter provides for filtration of particulates and adsorption of gases.
a base layer having an adsorptive material receiving surface and an exterior surface;
an adsorptive layer comprising an adsorptive material deposited on the adsorptive material receiving surface of said base layer in a discrete pattern to form an active-filtering and adsorbing media area; and a cover layer comprising a permeable fabric mounted to said base layer and enclosing the adsorptive material, wherein the filter has a Frazier permeability of at least 0.3 cubic feet per minute per square foot at one-half inch water pressure drop, wherein the filter provides for filtration of particulates and adsorption of gases.
2. A filter according to claim 1, wherein the adsorptive material comprises activated carbon.
3. A filter according to claim 2, wherein the activated carbon is impregnated with a solution selected from the group of water soluble carbonate, bisulfite, sulfate and hydroxide salts.
4. A filter according to claim 1, wherein the adsorptive material comprises an adsorptive material selected from the group of activated carbon, activated alumina, molecular sieves, ion exchange resins, functional resins and polymers, diatomaceous earths, silica or clays.
5. A filter according to claim 4, wherein the adsorptive material comprises a catalytic material selected from the group of copper, nickel, oxides of manganese, oxides of copper, and oxides of nickel.
6. A filter according to claim 1, wherein the adsorptive material comprises an acid removal agent selected from the group of low molecular weight amines and polymeric amines.
7. A filter according to claim 1, wherein the adsorptive material further comprises organic or inorganic halides.
8. A filter according to claim 1, wherein the adsorptive material further comprises sulfate salts.
9. A filter according to claim 1, wherein the adsorptive material is impregnated with 2,4 dinitrophenylhydrazine.
10. A filter according to claim 1, wherein the adsorptive slurry comprises a viscosity modifier.
11. A filter device according to claim 1, further comprising an annular adhesive layer applied to one side of the filter device.
12. A filter according to claim 1, wherein one of the base layer and the cover layer comprises a protective nonwoven layer and a HEPA membrane.
13. A filter according to claim 2, wherein the adsorptive material retains an adsorptive surface area capacity of at least 80% of the activated carbon material.
14. A filter according to claim 1, wherein said base layer comprises a multi-layer structure including a support layer, an efficiency membrane, and an adsorptive material holding layer.
15. A filter according to claim 1, wherein the absorptive material is in the form of a wetted slurry.
16. A filter according to claim 1, wherein the filter is a breather filter.
17. A filter according to claim 1, wherein the filter is a recirculation filter.
18. A filter according to claim 1, wherein the filter being manufactured by a process comprising the steps of:
(a) positioning the base layer approximate a screen member;
(b) depositing the adsorptive material through the screen member onto the adsorptive material receiving surface of the base layer;
(c) applying an adhesive onto the base layer; and (d) applying a cover sheet over the base layer and the absorptive material.
(a) positioning the base layer approximate a screen member;
(b) depositing the adsorptive material through the screen member onto the adsorptive material receiving surface of the base layer;
(c) applying an adhesive onto the base layer; and (d) applying a cover sheet over the base layer and the absorptive material.
19. A filter according to claim 18, further comprising an annular adhesive layer applied to one side of the filter.
20. A filter according to claim 18, wherein the base layer comprises a protective nonwoven layer and a HEPA membrane.
21. A filter according to claim 18, wherein the adsorptive material comprises activated carbon.
22. A filter according to claim 20, wherein the adsorptive material comprises a viscosity modifier.
23. A filter according to claim 18, wherein the filter is a breather filter or a recirculation filter.
24. A method of making a filter, comprising the steps of:
delivering a base layer to a rotary screen printer, wherein the base layer includes an absorptive material receiving surface;
applying an adsorptive material slurry in a discrete pattern to the adsorptive material receiving surface of the base layer; and applying a cover layer to the base layer to enclose the discrete pattern of adsorptive material slurry; wherein the filter provides for filtration of particulates and adsorption of gases.
delivering a base layer to a rotary screen printer, wherein the base layer includes an absorptive material receiving surface;
applying an adsorptive material slurry in a discrete pattern to the adsorptive material receiving surface of the base layer; and applying a cover layer to the base layer to enclose the discrete pattern of adsorptive material slurry; wherein the filter provides for filtration of particulates and adsorption of gases.
25. A method according to claim 24, wherein the rotary screen printer comprises a screen, and the adsorptive material is applied to a back portion of the screen and pressed onto the adsorptive material receiving surface of the base layer.
26. A method according to claim 24, wherein the adsorptive material is pressed into openings in the screen by a blade or roller.
27. A method according to claim 26, wherein the roller comprises a screen portion, and wherein the slurry is delivered through the screen portion to the adsorptive material receiving surface of the base layer.
28. A method according to claim 24, wherein the adsorptive material is applied as a wetted slurry, and is subsequently dried.
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EP (1) | EP0871533A1 (en) |
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-
1996
- 1996-05-01 CN CN96193843A patent/CN1184435A/en active Pending
- 1996-05-01 JP JP8534115A patent/JPH11506976A/en active Pending
- 1996-05-01 EP EP96913885A patent/EP0871533A1/en not_active Withdrawn
- 1996-05-01 BR BR9608384A patent/BR9608384A/en not_active Application Discontinuation
- 1996-05-01 WO PCT/US1996/006073 patent/WO1996035499A1/en not_active Application Discontinuation
- 1996-05-01 KR KR1019970707941A patent/KR19990008414A/en not_active Application Discontinuation
- 1996-05-01 AU AU56712/96A patent/AU5671296A/en not_active Abandoned
- 1996-05-01 CA CA002227716A patent/CA2227716A1/en not_active Abandoned
- 1996-05-10 ZA ZA9603717A patent/ZA963717B/en unknown
-
1997
- 1997-09-08 US US08/926,762 patent/US5869009A/en not_active Expired - Fee Related
-
1998
- 1998-06-18 US US09/099,561 patent/US6168681B1/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
BR9608384A (en) | 1999-01-19 |
WO1996035499A1 (en) | 1996-11-14 |
EP0871533A1 (en) | 1998-10-21 |
KR19990008414A (en) | 1999-01-25 |
US6168681B1 (en) | 2001-01-02 |
CN1184435A (en) | 1998-06-10 |
AU5671296A (en) | 1996-11-29 |
JPH11506976A (en) | 1999-06-22 |
US5869009A (en) | 1999-02-09 |
ZA963717B (en) | 1997-11-10 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
FZDE | Discontinued |