WO2001041901A1

WO2001041901A1 - Adsorbent assembly comprising polypropylene filtering layer for removing gaseous contaminants

Info

Publication number: WO2001041901A1
Application number: PCT/US2000/033185
Authority: WO
Inventors: Son T. Nguyen; Randy J. Logan; David J. Tuffley; Andre D. Leier
Original assignee: Donaldson Company, Inc.
Priority date: 1999-12-10
Filing date: 2000-12-07
Publication date: 2001-06-14

Abstract

An adsorbent filter assembly for removing contaminants and impurities. The assembly includes a microporous polypropylene membrane disposed over an adsorbent element.

Description

ADSORBENT ASSEMBLY COMPRISING POLYPROPYLENE FILTERING LAYER FOR REMOVING GASEOUS CONTAMINANTS

This application is being filed as a PCT International Patent application in the name of Donaldson Company, Inc., a U.S. national corporation, on 06 December 2000, designating China, Japan, Singapore and South Korea.

Field of the Invention

The present invention relates to an adsorbent filter assembly for removal of contaminants and impurities, as well as methods of making and using the adsorbent filter assembly and articles containing the adsorbent filter assembly. In particular, the invention includes an adsorbent filter assembly for insertion into the internal enclosure of a disk drive.

Background of the Invention

Adsorbent filters have a variety of uses, including uses in electronic equipment and chemical manufacturing and storage. For example, in the computer industry, adsorbent filters are used within the housings or casings of electronic devices to protect the electronic components from contaminants and impurities, such as water vapor, acid gases, and volatile organic compounds. For example, disk drives often include adsorbent filters within the enclosure of the disk drive or over an opening in the disk drive housing to protect the drive components and the disks from contaminants. Without such protection, these contaminants can lead to stiction, corrosion, and, in some instances, drive failure. Inclusion of an adsorbent filter improves the performance of the disk drive and extends its life. Typically, the adsorbent filter includes an adsorbent material, such as activated carbon or a desiccant, within the filter material. Pores within the filter allow contaminants to diffuse through the filter material and be adsorbed by the adsorbent material.

Summary of the Invention

The present invention relates to an adsorbent filter assembly for removal of contaminants and impurities, as well as methods of making and using the adsorbent filter assembly and articles containing the adsorbent filter assembly. The assembly can be used, for example, in the internal enclosure of a disk drive.

In particular, the filter assembly has an adsorbent element, a porous polypropylene filtering layer, and an adhesive base layer configured and arranged for mounting in the disk drive. Typically, the adhesive base layer includes an outer adhesive surface for adhesively mounting the filter assembly in the disk drive and an inner adhesive surface for attaching the polypropylene filtering layer. In one embodiment, the adhesive base layer includes a carrier layer which provides support for the inner and outer adhesive surfaces. A polypropylene filtering layer is disposed over the inner surface of the adhesive base layer to form a peripheral seal around the edge of the adsorbent filter assembly. In another embodiment, the adhesive surface on the inner surface is selectively disposed so that it is generally limited to the area of the peripheral seal. An adsorbent element is disposed between the adhesive base layer and the polypropylene filtering layer and is surrounded by the peripheral seal.

In some embodiments, the filter assembly is configured and arranged for non-adhesive mounting in the disk drive, for example, by a mounting member that passes through a portion of filter assembly.

In another embodiment, an adsorbent filter assembly for removing gaseous contaminants from a disk drive is provided. The filter assembly includes an adhesive base layer having opposing first and second surfaces. Disposed on a portion of the second surface of the base layer is an adhesive layer. Typically the adhesive layer of the second surface extends around the periphery of the base layer. Also disposed on the second surface of the base layer is an adsorbent element for adsorbing contaminants from the disk housing interior. A porous polypropylene filter layer is disposed over the adsorbent and forms, with the adhesive layer, a peripheral seal around the adsorbent element.

In at least some embodiments, the porous polypropylene filter layer has a smooth side and a rough side. The rough side of the polypropylene has propensity to release, eject, emit, or otherwise discharge polypropylene particulates (e.g., flakes, particles, or other particulates); that is, the rough surface loses material, for example, by flaking or sloughing off, and creates debris. Preferably, this rough side of the polypropylene filter layer is positioned adjacent the adsorbent element.

Another embodiment of the invention is a method of making an adsorbent filter assembly. The method includes providing an adhesive base material having a first adhesive surface and a second adhesive surface. An adsorbent element is placed on the second adhesive surface and covered with a porous polypropylene filtering membrane. In some embodiments, the porous polypropylene filter membrane has a smooth surface and a rough surface. This rough surface can be disposed adjacent the adsorbent material. The polypropylene filtering membrane is sealed to the second adhesive surface. In some embodiments, the rough side of the polypropylene filtering layer has a propensity to release polypropylene particulates.

In yet another embodiment, a combination of any of the adsorbent filter assemblies described above and a disk drive housing is provided. The combination can include a device housing, including therein a disk drive to be protected; and an adsorbent filter assembly for protecting the disk drive. The adsorbent filter assembly is mounted on an interior surface of the housing. The adsorbent filter assembly has a base layer having an outer surface; a first adhesive layer disposed on at least a portion of the outer surface of the base layer; and a second adhesive layer disposed on at least a portion of the base layer opposite the outer surface. A porous polypropylene filtering layer is disposed over the base layer and the second adhesive layer and forms, with the second adhesive layer, a peripheral seal. An adsorbent element is disposed between the base layer and the polypropylene filtering layer and within the peripheral seal.

Brief Description of the Drawings Figure 1 is a simplified schematic cross-section side view of the interior of a disk drive enclosure including an adsorbent filter assembly in accordance with the invention;

Figure 2 is a perspective top view of an adsorbent filter assembly in accordance with a first embodiment of the invention; Figure 3 is a cross-sectional view of the adsorbent filter assembly of

Figure 2 taken along line 3-3; Figure 4 is a cross-sectional view of a second embodiment of an adsorbent filter assembly in accordance with the invention;

Figure 5 is a cross-sectional view of a third embodiment of an adsorbent filter assembly in accordance with the invention; Figure 6 is a cross-sectional view of a fourth embodiment of an adsorbent filter assembly in accordance with the invention; and

Figure 7 is a cross-sectional view of a fifth embodiment of an adsorbent filter assembly in accordance with the invention.

Detailed Description of the Preferred Embodiments The present invention relates to an adsorbent filter assembly for use, for example, within the interior housing of a disk drive unit, as well as methods of making and using the adsorbent filter assembly and devices including the adsorbent filter assembly. The adsorbent filter assembly is designed to remove contaminants from the enclosure atmosphere by either adsorption or absorption. As used throughout this application, the terms "adsorb", "adsorption", "adsorbent" and the like, are intended to also include the mechanism of absorption and adsorption. While the present invention is not so limited, an appreciation of various aspects of the invention will be gained through a discussion of the examples provided below. The invention will be described with reference to the Figures, where like numerals are used to represent like elements throughout the Figures.

Referring to Figure 1, a housing enclosure 12 for a disk drive assembly 10 includes an adsorbent filter assembly 20 therein. Adsorbent filter assembly 20 is mounted on an inner surface 11 of enclosure 12. Also within enclosure 12 are a disk drive 14 and related mechanical systems (not shown) for operation of disk drive assembly 10. Adsorbent filter assembly 20 is mounted onto an interior surface 11 of enclosure 12, such as, for example, bottom surface 13, side wall surface 17, or top surface 19. Figure 1 shows adsorbent filter assembly 20 mounted to top surface 19 of enclosure 12. Disk drive assembly 10 and similar disk drive assemblies including the adsorbent filter assembly 20 can be used are found in numerous types of electronic equipment, for example, computers, video cameras, digital cameras, compact disc (CD) players, DVD players, and the like. The adsorbent filter assembly 20 can also be used with other electronic equipment and/or in other applications.

Adsorbent filter assembly 20 is mounted in enclosure 12 by adhesive mounting, by mechanical mounting, or both. The adsorbent filter assembly 20 can be placed within enclosure 12 during assembly of the disk drive unit 10. In one embodiment, shown in Figure 1, enclosure 12 includes a bottom portion 12A and a top portion 12B. During assembly of disk drive assembly 10, top portion 12B and bottom portion 12B of enclosure 12 are separated to allow access to disk 14 and the other mechanisms. Adsorbent filter assembly 20 can be mounted on bottom surface 13 or any other interior surface, e.g., on top surface 19 or a side surface 17, while top portion 12B and bottom portion 12A are separated.

Adsorbent Filter Assembly

Referring to Figure 1, adsorbent filter assembly 20 is used to adsorb or absorb gaseous contaminants, not shown, that are present in enclosure 12. These contaminants can damage disk drive assembly 10 and in particular disk drive 14. Common contaminants include, but are not limited to, dioctylphthalate, chlorine, hydrogen sulfide, nitrous oxide, mineral acid gases, silicone vapors, water vapor, and hydrocarbons. These and other contaminants can be generated within enclosure 12 or can come from an external source because enclosure 12 typically allows air exchange from the interior of enclosure 12 to the ambient atmosphere. Adsorbent filter assembly 20 is designed to remove these contaminants from the enclosure atmosphere by adsorption or absorption, as discussed above.

Referring now to Figure 2, adsorbent filter assembly 20 is shown from a top view as it would be seen if mounted onto a surface 1 1 of enclosure 12 (shown in Figure 1). Covering adsorbent filter assembly 20 is a polypropylene filtering layer 50. Under filtering layer 50 is an adsorbent element 40, shown in phantom. Filtering layer 50 is disposed over adsorbent element 40 and is attached to a base layer (not shown) by a continuous peripheral seal 22 around perimeter 21. Adsorbent filter assembly 20 has an outer perimeter 21 defining the shape of the assembly 20. Adsorbent filter assembly 20 is shown as generally rectangular in Figure 2, but could be any shape, for example, circular, square, trapezoidal, etc. The shape and size of adsorbent filter assembly 20 can be selected based on, for example, the application in which adsorbent filter assembly 20 is used. Figure 3 shows a cross-sectional view of adsorbent filter assembly 20 taken along line 3-3 in Figure 2. As can be seen, adsorbent filter assembly 20 includes an adsorbent element 40 enclosed between a polypropylene filtering layer 50 and an adhesive base layer 30. Adhesive base layer 30 has an outer surface 31 and an opposite inner surface 32. In the embodiment shown in Figure 3, inner surface 32 includes an adhesive surface 35 that occupies a first portion of inner surface 32, and an adsorbent/base interface surface 34 that occupies a second portion of inner surface 32. Adsorbent element 40 is positioned at the adsorbent/base interface surface 34. Polypropylene filtering layer 50 covers absorbent 40 and is attached to base layer 30 by adhesive surface 35 to form peripheral seal 22.

Figure 4 shows a cross-sectional view of another embodiment of an adsorbent filter assembly. Adsorbent filter assembly 20' has an adhesive base layer 30' with outer surface 31 and inner surface 32. Adhesive base layer 30' includes a first adhesive layer 30a, a carrier layer 30b, and a second adhesive layer 30a'. Second adhesive layer 30a', and thus adhesive surface 35', extends generally along the entire inner surface 32 of adhesive base layer 30'. An example of such an adhesive base layer 30', having first and second adhesive layers 30a, 30a' on a carrier layer 30b, is a double-sided adhesive tape. Together, polypropylene filtering layer 50 and adhesive base layer 30' enclose adsorbent element 40 by peripheral seal 22.

Adhesive Base Layer Referring again to Figure 3, adhesive base layer 30 has an outer surface 31 which forms an outermost surface of adsorbent filter assembly 20, and an inner surface 32. Outer surface 31 is the surface that is typically disposed adjacent the interior surface, such as bottom surface 13, of enclosure 12, onto which filtering assembly 20 is mounted. Inner surface 32 is opposite outer surface 31. Adhesive base layer 30 is, in the embodiment shown in Figure 3, a single layer of adhesive having outer surface 31 and inner surface 32. An example of such an adhesive base layer 30 is a layer of adhesive, that might be disposed between two release liners before incorporation into filtering assembly 20.

In another embodiment, such as shown in Figure 4, adhesive base layer 30' is a three layered construction: a first adhesive layer 30a, a carrier layer 30b, and a second adhesive layer 30a'. Another embodiment, such as shown in

Figure 5, has adhesive base layer 130 having a first adhesive layer 30a, a carrier layer 30b, and a second adhesive layer 130a that extends partially over carrier layer

30b.

Suitable adhesives that can be used as adhesive layers 30, 30a, 30a', 130a, include, but are not limited to, epoxy, acrylate and methacrylate, urethane, acrylic, latex and rubber adhesives. The adhesives can be pressure sensitive adhesives, hot melts, or removable and repositionable adhesives. The adhesive layers 30a, 30a', 130a are typically disposed on a carrier layer 30b. Suitable carrier layers 30b include polymer films, such as, for example, polyethylene, polypropylene, polyester, polycarbonate, polyurethane, or polyvinyl chloride films. Carrier layers 30b can be porous or non-porous and can be water permeable or non- permeable. A porous or permeable layer is generally a membrane that has an air permeability of at least about 0.03 cm/sec (0.05 ft/min) at a pressure drop of about 0.1 cm (0.05 inches) of water. The pores of a porous membrane are typically in the range of about 0.01 to 5 micrometers. Examples of porous or permeable materials suitable for carrier layer 30b include, but are not limited to, polyester, nylons, expanded polytetrafluoroethylene, polysulfones, and other polymers. The carrier layer 30b can also be a metallized polymer film. In some embodiments, base layer 30 may also include a molded or extruded thermoplastic piece. Double-sided tape, such as that made by coating an adhesive, commercially available from 3M under the trade designation 946 IP onto a Mylar^® polyester, is an example of a carrier with two layers of adhesive, which can be used for the adsorbent filter assembly 20.

In some embodiments, adhesive base layer 30 is marked or otherwise identified to differentiate it from polypropylene filtering layer 50. This can aid a user or assembler in correctly placing adsorbent filter assembly 20 in enclosure 12 so that air has access to, and can flow through, at least polypropylene filtering layer 50. Suitable markings include alphanumeric characters, symbols, colors, patterns, textures, and the like.

Polypropylene Filtering Layer A porous polypropylene filtering layer 50 is disposed over adhesive base layer 30 and adsorbent material 40 of adsorbent filter assembly 20. At the adhesive surface 35 of base layer 30, polypropylene filtering layer 50 forms a peripheral seal 22 along the perimeter 21 (shown in Figure 2) of the adsorbent filtering assembly 20. Polypropylene filtering layer 50 is a permeable polypropylene membrane that allows air flow through the layer. Polypropylene filtering layer 50 is preferably a microporous membrane or other permeable membrane or barrier that allows air and gaseous contaminants to permeate through the membrane or barrier. The polypropylene filter layer 50 for use in the invention is typically a membrane with a thickness of at least about 75 micrometers (about 3 mils) and a thickness of about 180 micrometers (about 7 mils) or less, although thinner or thicker membranes can be used. The thickness of the polypropylene filter layer 50 for at least some applications is about 140 to 180 micrometers. In one particular embodiment, a microporous polypropylene layer with a thickness of about 160 micrometers (6.3 mils) is used. A porous, or microporous, membrane has pores extending through or within the membrane. Typically, the pores are present in a tortuous arrangement within the membrane. The pores typically have a diameter of at least about 0.05 micrometers, and less than about 2 micrometers. For at least some applications, pores with diameters of about 0.1 micrometers to 1 micrometer are preferred. Microporous polypropylene membrane materials useful in the present invention include membranes available from Osmonics MSI of Westborough, MA, which include materials with pore diameters of 0.1 micrometer or 0.45 micrometer. "M045PBOO-00", which has a pore diameter of 0.45 micrometer, is an example of a suitable polypropylene membrane from Osmonics. One method of manufacturing microporous polypropylene membranes includes casting polypropylene on a smooth surface such as a belt or drum surface. This typically provides a smooth surface for one side of the polypropylene membrane. Solvents within the material are evaporated, producing the pores. In some instances, the finished material has one smooth surface and an opposite, rough surface. The rough surface is due, at least in part, to the evaporation of the solvent from the polypropylene. It has been found that this rough surface often has a propensity to release, eject, emit, or otherwise discharge polypropylene particulates (e.g., flakes, particles, or other particulate); that is, the rough surface loses material, for example, by flaking or sloughing off, and creates debris. This debris material is an undesirable contaminant that can cause problems with the operation of the disk drive 14 (Figure 1) and any other equipment present within enclosure 12.

In order to reduce, and preferably eliminate, the amount of debris released from the adsorbent filter assembly 20 into the enclosure 12, it is preferable that the smooth side of the membrane is positioned as the exterior surface of the polypropylene filtering layer 50 and the rough side is positioned adjacent the adsorbent element 40. With this configuration, minimal amounts of polypropylene particulates are typically introduced, into enclosure 12; rather, any material that may release from filtering layer 50 is retained within the adsorbent filter assembly 20.

Again referring to Figures 3 and 4, peripheral seal 22 is located along perimeter 21 (shown in Figure 2). Peripheral seal 22 is formed by sealing polypropylene filtering layer 50 to base layer 30 via adhesive surface 35, 35'.

Additionally or alternatively, filtering layer 50 can be sealed to base layer 32 with a mechanical connector such as staples, heat sealing or ultrasonic welding.

Adsorbent Element An adsorbent element 40 is disposed between adhesive base layer 30 and filtering layer 50 and is surrounded by peripheral seal 22. Adsorbent element 40 is disposed on adsorbent/base interface surface 34; this interface surface 34 can be adhesive, as shown in Figure 4, or non-adhesive, as shown in Figure 5. Adsorbent element 40 typically includes a physisorbent or chemisorbent material, such as, for example, desiccants (i.e., materials that adsorb or absorb water or water vapor) or materials that adsorb or absorb volatile organic compounds and/or acid gas. Suitable adsorbent materials include, for example, activated carbon, impregnated carbon, activated alumina, molecular sieves, silica gel, and impregnated carbon, alumina, and silica. These materials can be combined with or impregnated with, for example, potassium permanganate, calcium carbonate, potassium carbonate, sodium carbonate, calcium sulfate, or mixtures thereof. In some embodiments, the adsorbent material can be combined or impregnated with a second material.

Adsorbent element 40 can adsorb or absorb one or more types of contaminants, including, for example, water, water vapor, acid gas, and volatile organic compounds. Although adsorbent element 40 can be a single adsorbent material, mixtures of materials are also useful, for example, silica gel can be blended with carbon particles. In some embodiments, adsorbent element 40 includes layers or combinations of adsorbent material, so that different contaminants are selectively removed as they pass through the different adsorbent materials.

Typically, adsorbent element 40 is selected to be stable and adsorb contaminants within normal disk drive operating temperatures, for example, within a range of about 10°C to 50°C.

The adsorbent element 40 can be a powder (for example, it passes through 100 mesh) or granular material (28 to 200 mesh). Alternately, adsorbent element 40 can be shaped into a unitary form, such as a granule, bead, or tablet that optionally can be further shaped. In at least some instances, the shaped adsorbent article substantially retains its shape during the normal or expected lifetime of the adsorbent filter assembly 20. The shaped adsorbent article can be formed from a free- flowing particulate material combined with a solid or liquid binder that is then shaped into a non-free-flowing article. The shaped adsorbent article can be formed by, for example, a molding, a compression molding, or an extrusion process. The binder used can be dry, that is, in powdered and/or granular form, or the binder can be a liquid, solvated, or dispersed binder. In some embodiments, a temporary liquid binder, including a solvent or dispersant which can be removed during the molding process, is used. Typically, a binder that does not completely coat the adsorbent material is used. Suitable binders include, for example, latex, microcrystalline cellulose, polyvinyl alcohol, starch, carboxyl methyl cellulose, polyvinylpyrrolidone, dicalcium phosphate dihydrate, and sodium silicate. Preferably the composition of a shaped adsorbent article (i.e., adsorbent element 40) includes at least about 70%, by weight, and typically not more than about 98%, by weight, adsorbent. In some instances, the shaped adsorbent article includes 85 to 95%, preferably, approximately 90%, by weight, adsorbent material. The shaped adsorbent article typically includes not less than about 2%, by weight, binder and not more than about 30%, by weight, binder.

Further information regarding mold release, other additives, and molding techniques are discussed in U.S. Patent No. 5,876,487, the entire disclosure of which is incorporated herein by reference. Another embodiment of a suitable adsorbent element 40 includes a carrier. For example, a mesh or scrim can be used to hold the adsorbent material and binder. Polyester and other suitable materials can be used as the mesh or scrim. Typically, any carrier is not more than about 50% of the weight of the adsorbent, and is more often about 20 to 40% of the total adsorbent weight. The remainder of the shaped adsorbent article is the same or similar to that without the carrier. The amount of binder in the shaped adsorbed article with the carrier typically ranges about 10 to 50%) of the total adsorbent weight and the amount of adsorbent material typically ranges about 20 to 60% of the total adsorbent weight.

The adsorbent element 40 can have a shape that is the same as the overall shape of adsorbent filter assembly 20, such as shown in Figure 2 where both assembly 20 and adsorbent element 40 are rectangular. Alternately, adsorbent element 40 can have a shape different than that of adsorbent filter assembly 20.

Other Configurations In Figure 5, filter assembly 120 has an adhesive base layer 130 with outer surface 31 and inner surface 32. Adhesive base layer 130 has a first adhesive layer 30a having the outer surface 31 and a carrier layer 30b. Positioned on carrier layer 30b opposite first adhesive layer 30a is an adhesive layer 130a, which extends along a portion of carrier layer 30b. Adhesive layer 130a does not extend over the entire surface of carrier layer 30b as did adhesive layer 30a' in Figure 4; rather, adhesive layer 130a of Figure 5 extends only proximate to the perimeter 21 (shown in Figure 2) of adsorbent pouch assembly 120 to form peripheral seal 22, as shown in the top view of adsorbent pouch assembly 20 in Figure 2. In this embodiment of

Figure 5, adhesive layer 133a is used to provide attachment of base layer 130 to polypropylene filtering layer 50 via adhesive surface 35. Adsorbent element 40 sits on adsorbent/base interface surface 34. In other embodiments, the adhesive layer 30a may not cover the entire surface of carrier layer 30b. Instead, only portions of the outer surface 31 may be adhesive; the adhesive may be present only along the perimeter, or be present as a pattern, such as lines, dots, or the like.

In the embodiment shown in Figure 5, no adhesive extends between adsorbent element 40 and base layer 130; that is, the adsorbent/base interface surface 34 is a non-adhesive surface. Alternately, a portion of adhesive layer 35 can extend between adsorbent element 40 and base layer 130 to help adhere adsorbent element 40 to base layer 130, which can facilitate manufacture of the adsorbent filter assembly. In some instances, for example as shown in Figure 4, adsorbent element 40 is adhered to base layer 30' by adhesive layer 30a'; the adsorbent/base interface surface 34 is an adhesive surface.

Adsorbent filter assembly 20 can further include optional features, such as a hole 100, shown in Figure 6, used for mounting filter assembly 220 within enclosure 12, as will be discussed below. Preferably, hole 100 passes through an area of adsorbent filter assembly 220 where filtering layer 50 and base layer 30 are securely attached, so that no air can pass through to adsorbent element 40 without passing though filtering layer 50. Hole 100 is not needed for embodiments where adsorbent filter assembly 220 will be retained within enclosure 12 by adhesive mounting or by mechanical mounting with a mounting member 110 that does not require a hole 100, as will be discussed below. In Figure 7, adsorbent filter assembly 320 has base layer 30, polypropylene filtering layer 50, and adsorbent element 40, and further includes a carrier layer 60 positioned between base layer 30 and adsorbent element 40. Carrier layer 60 is typically a non-adsorbent material; carrier layer 60 can be a polymeric film, an adhesive, a molded plastic, paper, and the like. Carrier layer 60 retains stray adsorbent material that may otherwise contaminate base layer 30. A single or double-sided adhesive tape can be used. Examples of suitable materials for carrier layer 60 include "211" adhesive tape from American Papers, and "Delnet Nonwoven

P620 Boss Type Fabric" from Applied Extrusion Technologies.

Mounting The adsorbent filter assembly of the present invention can be adhesively or non-adhesively mounted in the disk drive assembly. In one embodiment, the adsorbent filter assembly is adhered to a surface of the disk drive enclosure 12 by an adhesive positioned on the assembly. Adsorbent filter assembly 20 of Figure 3 has an adhesive base layer 30. Figures 4 and 5 show embodiments of filter assemblies 20', 120 with a first adhesive layer 30a as the outermost layer. The adhesive layer 30a can be coated onto the a carrier layer 30b before, during or after assembly of the filter assembly, or the adhesive layer can be integral with the base layer (such as in Figures 4 and 5).

In at least some instances, the disk drive assembly includes at least one mounting member to facilitate mounting of the adsorbent filter assembly. Referring to Figure 6, an adsorbent filter assembly 220 includes an adsorbent element 40 disposed between filtering layer 50 and base layer 230; adsorbent filter assembly 220 is mounted to bottom surface 13 using a mounting member 110. Base layer 230 has an outer surface 231 which can be an adhesive surface, but typically is a non-adhesive surface. A non-adhesive surface can be created by providing a non- adhesive layer over an adhesive outer surface.

In general, mounting member 1 10 can be any mechanism that is capable of securing, grasping, gripping, retaining, mounting or otherwise holding adsorbent filter assembly 220 to any interior surface of the disk drive enclosure 12. One example of mounting member 1 10 is any object that can be passed through hole 100 in adsorbent filter assembly 20, such as a pin, a post, a screw, a rivet, a bolt, a nail, and the like. Any of these mounting members 110 can be straight or bent. A single mounting member 1 10 can be used, or multiple mounting members 110 can be used to secure a single adsorbent filter assembly 220. Additional details regarding non-adhesive mounting of the adsorbent filter assembly, and additional embodiment of mounting members, can be found in Assignee's co-pending patent application Serial No. 09/347,378, filed July 6, 1999, and incorporated herein by reference.

Method of Manufacturing an Adsorbent Pouch Assembly One method of manufacturing adsorbent filter assemblies is with a rotary press. To manufacture adsorbent filter assembly 20, a web of adhesive base layer 30 material is provided. A release liner can be present on the outer surface 31.

In one manufacturing example, an adhesive base layer 30' (such as shown in Figure 4) includes a first adhesive layer 30a on a carrier 30b and a second adhesive layer 30a' that extends over generally the entire surface of the base layer; this can be provided as a web of double-sided PSA tape. In another embodiment, either first adhesive layer 30a or second adhesive layer 30a' can be a layer of liquid adhesive applied via, for example, knife blade, roll coating, or other coating method onto a single-sided PSA tape. Adsorbent element 40 is positioned on base/adsorbent interface surface 34 with sufficient spacing between adjacent adsorbent material so that a complete peripheral seal 22 can be made. A web of polypropylene filtering layer 50 material is placed over adsorbent element 40. If the polypropylene used for polypropylene filtering layer 50 has a rough surface that has a tendency to release debris, this rough surface is positioned against adsorbent element 40. Once all layers have been assembled, peripheral seal 22 is formed as the individual adsorbent filter assemblies are cut. For example, a die that both provides pressure to create peripheral seal 22 and is sufficiently sharp to cut perimeter 21 may be used. Alternately, polypropylene filtering layer 50 can be pressed against the second adhesive layer 30a' of base layer 30' in order to form peripheral seal 22 before individual adsorbent filter assemblies 20' are cut.

To provide an adhesive layer 130a as shown in Figure 5, portions of one of the adhesive layers of a double-sided PSA tape can be partially removed. This may be done by a kiss-cutting method, where preferably only the adhesive layer 130a is cut or scored, and the cut or scored portions are removed. The area from where the adhesive is removed is the base/adsorbent interface surface 34 on which adsorbent element 40 is positioned. In another manufacturing example, a pattern of adhesive can be applied to a surface of carrier layer 30b opposite first adhesive layer 30a as, for example, stripes or lines of adhesive to form adhesive layer 130a. The adhesive can be applied by coating methods that are well known, such as gravure coating or screen printing. Adsorbent element 40 is positioned on base/adsorbent interface surface 34 of adhesive base layer 30 between the lines of adhesive layer 130a. A web of polypropylene filtering layer 50 material is placed over adsorbent element 40 and a peripheral seal 22 is provided as discussed above.

An in yet another manufacturing example, a continuous layer of adsorbent element 40 is positioned on a carrier layer or lamination base material (shown in Figure 7). This laminated sheet is then adhered to base layer 30. Adsorbent element 40, along with the carrier base material is cut and the waste material is removed to provide discrete pieces of adsorbent element 40 with the carrier base material disposed on base layer 30. The polypropylene filtering layer 50 is placed over adsorbent element 40, as described above. The carrier base material, onto which adsorbent element 40 is laminated, facilitates manufacturing of the overall filter assembly. The carrier layer is one that will readily adhere to adsorbent element 40 but that can preferably be easily removed from the adhesive base layer 30, for example in the areas of adsorbent that are to be removed. Addition of the carrier layer improves manufacturing by containing small individual adsorbent particles that could contaminate base layer 30 when the adsorbent element waste material is removed.

In some embodiments, it is preferred that instead of cutting individual separate adsorbent assemblies, the web of assemblies is scored or serrated, so that the adsorbent pouch assemblies can be later individually separated.

The outer surface 31 of adhesive base layer 30 can be covered with a release liner to allow the assembly web to be neatly rolled and packaged.

Examples of Adsorbent Pouch Assemblies The size, shape, and configuration, of adhesive base layer 30, 30', adsorbent element 40, filtering layer 50, and overall adsorbent filter assembly 20, 20', 120, 220 depend on the intended use of adsorbent filter assembly. In some embodiments, it is desirabh that the adsorbent filter assembly is streamlined to prevent or minimize air flo N disturbance or air flow resistance, for example, within disk drive assembly 10.

As one example, an adsorbent filter assembly for use in a computer disk drive assembly can have outer dimensions of about 5 to 20 mm by 10 to 20 mm when measured at perimeter 22, and an overall thickness of about 1 to 4 mm.

In one example, adhesive base layer 30 is a single layer of adhesive with no carrier layer. Preferably, the adhesive of adhesive base layer 30 has sufficient integrity and strength to retain its shape. Such an adhesive can be provided between two release liners until used.

Alternately, adhesive base layer 30' is a layer, for example, polyester such as Mylar^® film, having a thickness greater than about 25 micrometers (1 mil), onto which are coated adhesive layers. Preferably, the thickness is less than about 150 micrometers (6 mils). In some embodiments, the thickness of base layer 32 ranges from about 50 to 100 micrometers (2 to 4 mils). In one example, adhesive base layer 30' is a double sided tape, made by coating adhesive, such as that commercially available from 3M under the trade designation 9462P, onto Mylar^® film. Each adhesive layer 30a, 30a' has a thickness of about 50 micrometers (2 mils) and the carrier film 30b has a thickness of about 25 to 50 micrometers (1 to 2 mils). Adsorbent element 40 can be free-flowing particulate or can be shaped. Adsorbent element 40 can occupy an area between about 0.5 cm² and 3 cm² when viewed from the top as in Figure 2, although this area will vary, depending on the size of the adsorbent filter assembly and the application in which it is used. The area occupied by adsorbent element 40 can be shaped the same as or be shaped different than the shape of the adsorbent filter assembly. A thin adsorbent element 40, for example, with a thickness of about 0.3 to 1.5 mm (about 15 to 60 mils), can be used in applications where it is desired to streamline the adsorbent filter assembly. In other embodiments, adsorbent element 40 can be about 2 to 4 mm (80 to 160 mils) in thickness. Over adsorbent element 40 is polypropylene filtering layer 50, through which air can permeate to allow any contaminants in the air to be adsorbed by adsorbent element 40. Polypropylene filtering layer 50 is a porous polypropylene material, having a thickness greater than about 25 micrometers (1 mil).

Additionally, polypropylene filtering layer 50 typically has a thickness less than about 0.5 mm (20 mils). Generally, the thickness of polypropylene filtering layer 50 is from about 50 to 305 micrometers (2 to 12 mils), and typically, the thickness of polypropylene filtering layer 50 is from about 125 to 260 micrometers (5 to 10 mils), although thicker and thinner layers 50 can be used.

The air permeability of polypropylene filtering layer 50 is typically at least about 0.091 cm/sec (0.18 ft/min) at a pressure drop of about 1.27 cm (0.5 inches) of water. It should be noted that the thickness, ranges, etc. disclosed in this example are not in any way limiting but are provided as a guide.

The above specification, examples and data provide a complete description of the manufacture and use of the assembly of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

Claims

WE CLAIM:

1. An adsorbent filter assembly for removing gaseous contaminants from a disk drive, the filter assembly comprising:

(a) an adhesive base layer having an inner surface and an outer surface;

(b) an adsorbent element disposed on the inner surface of the adhesive base layer;

(c) a porous polypropylene filtering layer disposed over the adsorbent material and adhered to the inner surface of the adhesive base layer, the polypropylene filtering layer and the adhesive base layer forming a peripheral seal around the adsorbent material.

2. The adsorbent filter assembly of claim 1, wherein the polypropylene filtering layer has a smooth side and a rough side, and the rough side is disposed adjacent the adsorbent element.

3. The adsorbent filter assembly of claim 2, wherein the rough side of the polypropylene filtering layer disposed adjacent the adsorbent element has a propensity to release polypropylene particulates.

4. The adsorbent filter assembly of claim 1, wherein the adhesive base layer has a first adhesive layer which defines the outer surface of the adhesive base layer and a second adhesive layer which defines the inner surface of the adhesive base layer.

5. The adsorbent filter assembly of claim 4, wherein the adhesive base layer is a double-sided adhesive tape.

6. The adsorbent filter assembly of claim 1 , wherein the adhesive base layer has a first adhesive layer which defines at least a portion of the outer surface of the adhesive base layer and a second adhesive layer which defines at least a portion of the inner surface of the adhesive base layer.

7. The adsorbent filter assembly of claim 1, wherein the adsorbent element comprises a material selected from the group consisting of activated carbon; activated alumina; molecular sieves; silica gel; a material impregnated with at least one material selected from the group consisting of potassium permanganate, calcium carbonate, potassium carbonate, sodium carbonate and calcium sulfate; and combinations thereof.

8. The adsorbent filter assembly of claim 1, wherein the adsorbent element comprises an adsorbent material and a carrier.

9. The adsorbent filter assembly of claim 1, wherein the filtering layer and adhesive base layer define an opening adapted for passing a mounting member therethrough.

10. The adsorbent filter assembly of claim 1, wherein the adsorbent filter assembly is configured and arranged for non-adhesively mounting on a surface of the disk drive with the outer surface of the adhesive base layer adjacent the surface of the disk drive.

11. The adsorbent filter assembly of claim 1, further comprising a carrier base layer disposed between the adsorbent element and the inner surface of the adhesive base layer.

12. A combination of a disk drive and an adsorbent filter assembly, the combination comprising:

(a) a device housing including therein a disk drive to be protected; and

(b) an adsorbent filter assembly for protecting the disk drive, wherein the adsorbent filter assembly is mounted on an interior surface of the housing, the adsorbent filter assembly comprising:

(i) a base layer having an outer surface;

(ii) a first adhesive layer disposed on at least a portion of the outer surface of the base layer; (iii) a second adhesive layer disposed on at least a portion of the base ayer opposite the outer surface; (iv) a porous polypropylene filtering layer disposed over the base layer and the second adhesive layer and forming, with the second adhesive layer, a peripheral seal; and (v) an adsorbent element disposed between the base layer and the polypropylene filtering layer and within the peripheral seal.

13. The combination of claim 12, wherein the polypropylene filtering material has a smooth side and a rough side, and wherein the rough side is disposed adjacent the adsorbent element.

14. The combination of claim 13, wherein the rough side of the polypropylene filter material has a propensity to release polypropylene particulates.

15. The combination of claim 12, wherein the first adhesive layer of the adsorbent filter assembly is disposed over the entire outer surface of the base layer.

16. The combination of claim 12, wherein the second adhesive layer of the adsorbent filter assembly is disposed over the entire inner surface of the base layer.

17. The combination of claim 12, wherein the base layer, the first adhesive layer and the second adhesive layer form a double-sided adhesive tape.

18. The combination of claim 12, wherein the adsorbent element comprises a material selected from the group consisting of activated carbon; activated alumina; molecular sieves; silica gel; a material impregnated with at least one material selected from the group consisting of potassium permanganate, calcium carbonate, potassium carbonate, sodium carbonate and calcium sulfate; and combinations thereof.

19. The combination of claim 12, wherein the adsorbent element comprises an adsorbent material and a carrier.

20. A method of making an adsorbent filter assembly, the method comprising steps of:

(a) providing an adhesive base material having a first adhesive surface and a second adhesive surface;

(b) placing an adsorbent element on the second adhesive surface;

(c) covering the adsorbent element with a porous polypropylene filtering membrane; and

(d) sealing the polypropylene filtering membrane to the second adhesive surface.

21. The method of making an adsorbent filter assembly of claim 20, wherein the step of covering the adsorbent element with a porous polypropylene filtering membrane comprises covering the adsorbent element with a porous polypropylene filter membrane having a smooth surface and a rough surface, wherein the rough surface is disposed adjacent the adsorbent material

22. The method of making an adsorbent filter assembly of claim 21, wherein the step of covering the adsorbent element with a porous polypropylene filter membrane having a smooth surface and a rough surface comprises covering the adsorbent element with a porous polypropylene filtering membrane having a smooth surface and a rough surface with a propensity to release polypropylene particulates.

23. The method of making an adsorbent filter assembly of claim 20, further comprising placing a carrier base between the adsorbent element and the second adhesive surface.