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WO2018152683A1 - Ensemble filtres en couches pour protection d'enceinte - Google Patents

Ensemble filtres en couches pour protection d'enceinte Download PDF

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Publication number
WO2018152683A1
WO2018152683A1 PCT/CN2017/074345 CN2017074345W WO2018152683A1 WO 2018152683 A1 WO2018152683 A1 WO 2018152683A1 CN 2017074345 W CN2017074345 W CN 2017074345W WO 2018152683 A1 WO2018152683 A1 WO 2018152683A1
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WO
WIPO (PCT)
Prior art keywords
layer
assembly
filtration
filtration layer
porous support
Prior art date
Application number
PCT/CN2017/074345
Other languages
English (en)
Inventor
Rajan Gidumal
Jiangwen YIN
Xiao Xi Liu
Hong NING
Pan WANG
Original Assignee
W. L. Gore & Associates, Inc.
W. L. Gore & Associates Technologies (Shenzhen) Co, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by W. L. Gore & Associates, Inc., W. L. Gore & Associates Technologies (Shenzhen) Co, Ltd. filed Critical W. L. Gore & Associates, Inc.
Priority to PCT/CN2017/074345 priority Critical patent/WO2018152683A1/fr
Priority to CN201780003244.7A priority patent/CN108770347B/zh
Publication of WO2018152683A1 publication Critical patent/WO2018152683A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/022—Non-woven fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/02—Types of fibres, filaments or particles, self-supporting or supported materials
    • B01D2239/0208—Single-component fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0407—Additives and treatments of the filtering material comprising particulate additives, e.g. adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/0604—Arrangement of the fibres in the filtering material
    • B01D2239/0622—Melt-blown
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B01D2239/0654—Support layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/1233—Fibre diameter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0276—Polyester fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0276—Polyester fibres
    • B32B2262/0284—Polyethylene terephthalate [PET] or polybutylene terephthalate [PBT]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/726—Permeability to liquids, absorption

Definitions

  • the present disclosure relates generally to filter assemblies for capturing particulate and/or vapor contaminants, and methods for mitigating contamination of an electronic device enclosure.
  • Filter technology is utilized in many applications and environments, for protecting sensitive components of electronic devices (e.g. hard disk drives (HDD’s) ) from particulate and/or vapor contamination within electronic device enclosures.
  • electronic devices e.g. hard disk drives (HDD’s)
  • HDD hard disk drives
  • enclosures that contain sensitive equipment must maintain very clean environments in order for the equipment to operate properly. Examples include enclosures for the following: optical surfaces or electronic components that are sensitive to particulates and gaseous contaminants which can interfere with mechanical, optical, or electrical operation; data recording devices, such as computer hard disk drives that are sensitive to particles, organic vapors, and corrosive vapors; processing and storage of thin films and semiconductor wafers; and electronic controls such as those used in automobiles and industrial applications that can be sensitive to particulates, moisture buildup and corrosion as well as contamination from fluids and vapors. Contamination in such enclosures originates from both inside and outside the enclosures. For example, HDD’s may be damaged as a result from external contaminants entering and/or recirculating within the enclosure for the HDD. The contaminants may also include particulates and vapors generated from inside the HDD enclosure.
  • Known filters are disclosed in, for example, U.S. Patent No. 7,306,659, (the ‘659 patent) which is hereby incorporated by reference for all purposes.
  • the ‘659 patent discloses a device for filtering contaminants, such as particulates and vapor phase contaminants, from a confined environment such as electronic or optical devices susceptible to contamination (e.g. computer disk drives) by improving performance and possibly incorporating multiple filtration functions into a unitary filter.
  • the filter includes flow layers which improve filter performance.
  • Filtration functions include a passive adsorbent assembly and can include a combination of inlet, breather filter, and adsorbent filter.
  • recirculation filter, diffusion tube and outside mount functions can be added to the filter depending on desired functionality within the enclosure.
  • U.S. Patent No. 6,266,208 describes a unitary filter incorporating a recirculation filter, breather filter, and adsorbent filter.
  • U.S. Patent No. 6,238,467 describes a rigid assembly filter incorporating a breather filter, adsorbent filter, and recirculation filter.
  • U.S. Patent No. 6,296,691 describes a molded filter incorporating a breather filter and recirculation filter.
  • U.S. Patent No. 6,395,073 describes incorporating a recirculation filter and a breather filter with an optional adsorbent filter into a low profile adhesive construction.
  • a layered filter assembly comprising a filtration layer and one or more porous support layers adjacent to the filter layer.
  • the porous support layers can be positioned along one side, or along both sides, of the filter layer; and can be configured to provide support for the filter layer without significantly adding to the air resistance of the layered filter assembly.
  • the porous support layers contact the filtration layer without any intervening layers.
  • the assembly can have a filtration efficiency of 65%or greater, and a thickness on the order of 100 to 250 ⁇ m.
  • a layered filter assembly comprising a filtration layer, one or more porous support layers, an adsorbent layer and a media layer, where the adsorbent layer is positioned between the filtration layer and the media layer.
  • the one or more porous support layers are positioned adjacent to and exterior to the filtration layer and/or the media layer.
  • an article for filtering an enclosure includes a housing for retaining an electronic device, a layered assembly arranged inside the housing, and a filtration layer comprising a polyester layer.
  • the layered assembly includes a filtration layer and one or more porous support layers adjacent to the filtration layer.
  • the filter layer can be formed of nonwoven polyester with non-uniform fiber sizes ranging from 0.1 micron to 10 micron.
  • the filter layer can be meltblown polyester that is substantially free of polypropylene.
  • substantially free means that the component is present in limited quantities of less than 0.1 wt. %, and includes being completely free of the component.
  • FIG. 1 is a side cross-sectional view of an embodiment of a layered filter assembly.
  • FIG. 2 is a side cross-sectional view of a second embodiment of a layered filter assembly.
  • FIG. 3 is a side cross-sectional view of a third embodiment of a layered filter assembly.
  • FIG. 4 is a scanning electron micrograph (SEM) image showing a filtration material having substantially uniform fibers.
  • FIG. 5 is an SEM image showing a filtration material having non-uniform fiber size, according to embodiments described herein.
  • FIG. 6 is a side cross-sectional view of an electronic device assembly showing a layered filter assembly as per FIGS. 1-3 installed therein, according to embodiments described herein.
  • FIG. 7 is a side cross-sectional view of a filtration efficiency test assembly and system.
  • FIG. 8 is a chart illustrating filtration efficiency of various test samples.
  • a layered filter assembly comprising a filtration layer and one or more porous support layers arranged adjacent to the filtration layer.
  • the filtration layer includes polyester comprising fibers with a non-uniform fiber size ranging from 0.1 ⁇ m to 10 ⁇ m.
  • the filtration layer may also be substantially free of polypropylene.
  • the layered filter assemblies are suitable for use in, e.g., electronic device enclosures. The layered filter assemblies can be used to filter air therein without occupying too much space, without significantly impeding airflow, without shedding fibers into the enclosure, and without the drawbacks associated with conventional (e.g. polypropylene) filtration layers.
  • the adsorbent layer may be positioned between the filtration layer and media layer, and the porous support layers arranged adjacent to the opposite surface of the filtration and media layers.
  • the adsorbent layer can include any suitable adsorbent material, such as but not limited to, activated carbon or a porous substrate containing activated carbon.
  • the adsorbent layer may comprise ePTFE and an adsorbent material.
  • Other suitable adsorbent materials can include, but are not limited to: sodium carbonate, calcium carbonate, calcium sulfate, potassium carbonate, any suitable mixture of the above, or a suspension of any suitable combination of the above in a substrate.
  • the media layer can have similar characteristics to the filtration layer, such that the adsorbent layer is positioned essentially between two layers with similar characteristics.
  • FIG. 4 is a scanning electron micrograph (SEM) image showing a filtration material 400 having substantially uniform fibers 402 in a conventional polypropylene electret felt material.
  • FIG. 5 is an SEM image showing a polyester filtration material 500 having non-uniform fiber size, in accordance with some embodiments of the present disclosure.
  • the layered filter assembly 100 includes a filtration layer 102 and two porous support layers 104a, 104b positioned adjacent to the filtration layer and on either side of the filtration layer.
  • the filtration layer 102 is a polyester layer having fibers with a non-uniform fiber size, in which fibers can range in size from 0.1 ⁇ m to 10 ⁇ m. It is understood that fiber size is determined by the cross-sectional diameter.
  • a non-uniform fiber sizes means that the fibers in the polyester layer have different cross-sectional diameters that produces a distribution of fiber sizes.
  • non-uniform fiber size may range from 0.1 ⁇ m to 10 ⁇ m, there may be some individual fibers that are smaller or larger.
  • the distribution of the fiber sizes can vary, so that for example, in one embodiment a first portion of the fibers are in the range of 0.1 ⁇ m to 3.0 ⁇ m, and a second portion of the fibers are in the range of 3.0 ⁇ m to 10 ⁇ m.
  • the first portion may be from 10%to 90%of the total fibers and the second portion may be from 90%to 10%of the total fibers.
  • the fibers have a fiber size in the range from 0.1 ⁇ m to 3.0 ⁇ m, and 15%of the fibers have a fiber size in the range from 3.0 ⁇ m and 5.0 ⁇ m.
  • the fiber size can have a bimodal distribution, having a first average fiber size in the range of 0.1 to 3.0 ⁇ m, and a second average fiber size in the range of 3.0 to 5.0 ⁇ m.
  • the first average fiber size range can include approximately 85 %of the fibers
  • the second average fiber size range can include approximately 15 %of the fibers.
  • the fiber size distribution can be multimodal.
  • the filtration layer 102 is a meltblown polyester polymer.
  • the filtration layer 102 is a meltblown polybutylene terephthalate.
  • the filtration layer 102 can be substantially free of polypropylene.
  • the filtration layer 102 may comprise an electrospun non-polypropylene polymer nonwoven, or a multicomponent spun non-polypropylene polymer nonwoven.
  • the suitable filtration layer has an adequate flow and resistance properties, while being thin and lightweight.
  • the filtration layer 102 has a gas permeability of at least 15.24 cubic meters of air /min m 2 (m/min) , or 50 cubic feet air /min ft 2 (cfm /ft 2 ) at 125 Pa.
  • the filtration layer 102 has a gas permeability in the range of 15.24 m/min to 30.5 m/min (i.e., 50 to 100 cfm /ft 2 ) at 125 Pa.
  • the filtration layer 102 can have an air resistance of less than 20 Pa.
  • the filtration layer may be lightweight and is able to made thin for small enclosures.
  • the filtration layer 102 has a thickness 110 of less than 250 ⁇ m, e.g., less than 200 ⁇ m.
  • a suitable filtration layer may have a thickness in the range of 100 ⁇ m to 250 ⁇ m.
  • the filtration layer may have weight in the range of 15 g/m 2 to 50 g/m 2 , e.g., from 22 g/m 2 to 40 g/m 2 .
  • the filtration layer also has a sufficient collection efficiency over a wide range of particulate sizes, such as from 0.05 ⁇ m to 10 micrometers.
  • porous support layers 104a, 104b Two porous support layers 104a, 104b are shown, but it will be understood that in some embodiments one of the two porous support layers may be omitted.
  • the porous support layer or layers 104a, b preferably have a porosity that is significantly greater than that of the filtration layer 102, such that the porous support layer (s) do not significantly impair the gas permeability of or airflow through the filtration layer.
  • the porous support layer (s) 104a, b can be constructed of any suitable support material, such as a woven scrim with a high gas permeability compared to that of the filtration layer 102.
  • the porous support layer (s) 104a, b may be constructed of a non-polypropylene material, such as a polyester woven.
  • the porous support layer (s) 104a, b may be constructed of, e.g. polyethylene, polyvinyl alcohol, a mixture of the above, or other similar material.
  • the porous support layer (s) have a gas permeability of at least 152 cubic meters air /m 2 (500 cfm /ft 2 ) at 125 Pa.
  • the porous support layers 104a, b can have thicknesses 112a, b, on the order of 100 to 400 ⁇ m.
  • the layered filter assembly 100 can be assembled, in some embodiments, by laying the porous support layers 104a, b across the filtration layer 102 so as to support the filtration layer and/or prevent release of fibers from the filtration layer. This means that the distances 120, 122 between the filtration layer 102 and the porous support layers 104a, b can be very small, i.e. approximately zero microns.
  • the filtration layer 102 and the porous support layers 104a, b may be joined at one or more sides or edges, e.g. by mechanical means (including clamps, potting, or any suitable mechanical fasteners) ; by joining or laminating along one or more sides or edges of an assembly, or by joining the layers by an adhesive.
  • the filtration layer 102 can include thermal melt adhesive layer (s) on one or more surfaces (not shown) capable of being adhered to one or more of the adjacent porous support layers 104a, b.
  • the layered filter assembly 100 is operable to filter a flow of air flowing therethrough by removing a substantial amount of entrained small particles.
  • Exemplary embodiments of the layered filter assembly 100 were tested on a TSI-8130 Automated Filter Tester (TSI Inc. ) with 0.3 ⁇ m NaCL particles at a flow rate of 5.3 cm/s, as described in greater detail below with reference to Table 1.
  • the exemplary embodiments of the layered filter assembly 100 achieved filtration efficiencies of at least 65 %at a flow rate of 32 liters per minute (LPM) .
  • the layered filter assembly 100 can also achieve filtration efficiencies of 80 %or greater.
  • the layered filter assembly 100 can have a total airflow resistance of less than 30 Pa, e.g. less than 20 Pa; or in the range from 10 Pa to 30 Pa, e.g. from 15 Pa to 20 Pa.
  • a layered filter assembly can further include one or more adhesive elements or layers positioned exterior to the one or more porous support layers 104a, b, e.g. for adhering to a housing or other device that receives the layered filter assembly.
  • the layered filter assembly may also include a damping material for reducing vibration within the housing.
  • the layered filter assembly can include additional layers, such as an adsorbent layer, media layer, and/or second filtration layer. Examples of layered filter assemblies having additional layers are described below with reference to FIG. 2 and FIG. 3.
  • FIG. 2 shows a side cross-sectional view of a second embodiment of a layered filter assembly 200.
  • the second layered filter assembly 200 includes a filtration layer 202, as well as an adsorbent layer 206 and a media layer 208 positioned opposite the adsorbent layer from the filtration layer.
  • the combination of the filtration layer 202, adsorbent layer 206, and media layer 208 can be bounded by adjacent porous support layers 204a, 204b.
  • the filtration layer 202 and the porous support layers 204a, b can have structures and characteristics that are similar to the filtration layer 102 and porous support layers 104a, b described above with reference to FIG. 1.
  • the adsorbent layer 206 can include any suitable adsorbent porous support layer, such as but not limited to, activated carbon or a porous substrate containing activated carbon.
  • a suitable adsorbent porous support layer may include a plurality of activated carbon beads or grains disposed between two scrim.
  • the adsorbent layer is preferably operable to adsorb vapor contamination from a flow of air flowing through the layered filter assembly 200 such as organic vapors.
  • the media layer 208 positioned adjacent to the adsorbent layer 206 and opposite the filtration layer 202, is operable to prevent dispersion of particulates from the adsorbent layer 206, but is generally more porous than the filtration layer 202, i.e. having a lower air resistance than the filtration layer. Air resistance of a media layer may less than the filtration layer, and may be less than 3 Pa.
  • the media layer can have a thickness in the range of 0.5 to 1.3 mm, e.g., 1.0 to 1.3 mm. Suitable materials for the media layer can include, e.g., nonwovens and particularly nonwoven polyesters formed by a carding, spunbond, or meltblown process. In one embodiment, the media layer is polyester meltblown, such as a polyethylene terephthalate nonwoven.
  • the layers comprising the layered filter assembly 200 can be separated by distances 220, 222, 224, 226. Some or all of the separation distances can be zero or approximately zero.
  • the layers may be assembled by mechanically fastening the layers into the layered filter assembly 200 at edges or at separated points along the filter assembly.
  • the layers may be bonded to one another at edges or at discrete points along the adjacent surfaces.
  • the layers may be bonded continuously along the adjacent surfaces to one another.
  • the filtration layer 202 and/or media layer 208 may include thermal melt adhesive layer (s) on one or more surfaces (not shown) capable of being adhered to one or more of the adjacent porous support layers 204a, b.
  • the filtration layer 202 and/or media layer 208 may be bonded to the adsorbent layer 206 by way of a melt adhesive layer or similar.
  • FIG. 3 is a side cross-sectional view of a third embodiment of a layered filter assembly 300.
  • the third layered filter assembly 300 includes a first filtration layer 302a and a second filtration layer 302b which is positioned similar to the media layer 208 of the example assembly 200 shown in FIG. 2.
  • the second filtration layer 302b may also be referred to as a media layer, and perform the same functions as the media layer 208 described above with reference to FIG. 2.
  • the layers comprising the layered filter assembly 300 can be separated by distances 320, 322, 324, 326.
  • the separation distances can be zero or approximately zero, and the layers may be attached together by one or more of the methods discussed above with reference to the layered filter assemblies 100 and 200.
  • exemplary large fibers 502 are shown with approximate diameters ranging from 3 ⁇ m to 5 ⁇ m in a nonwoven arrangement with small fibers 504 having approximate diameters ranging from 0.1 ⁇ m to 3 ⁇ m.
  • the filtration material 500 is meltblown polyester. Specific polyesters include, e.g., polybutylene terephthalate, but other polyester meltblown materials are within the scope of this disclosure. The distribution of fiber sizes in the meltblown polyester is varied.
  • a suitable fiber size distribution includes a first range of fiber sizes between 0.1 ⁇ m and 3.0 ⁇ m comprising up to 85 %of the fibers, and a second range of sizes between 3.0 ⁇ m and 5.0 ⁇ m comprising up to 15 %of the fibers.
  • Polyester meltblown materials such as the filtration material 500 described above can be formed by a one-step process in which high-velocity air blows a molten thermoplastic resin onto a conveyor. Suitable processes for producing polyester meltblown materials are discussed in, e.g., Dutton, K.C. (2008) . “Overview and analysis of the meltblown process and parameters" . Journal of Textile and Apparel, Technology and Management. 6; and in McCulloch, J. G. (1999) . "The history of the development of melt blowing technology” . International Nonwovens Journal. 8, which are hereby incorporated by reference.
  • the range of fiber sizes in the polyester filtration material 500 is operable to trap particles more effectively than a filtration material having a uniform fiber sizes, particularly for very small particles.
  • this improvement of the polyester filtration material over the electret felt is unexpected.
  • Sample raw material properties for the exemplary polypropylene 400 and polyester meltblown 500 filtration materials are shown below with reference to Table 1.
  • Table 1 shows materials properties for electret felt and polyester meltblown filtration materials described above, with the air resistance and efficiency metrics obtained on a TSI-8130 Automated Filter Tester (TSI Inc. ) with 0.3 ⁇ m NaCL particles at a flow rate of 5.3 cm/s.
  • TSI-8130 Automated Filter Tester TSI Inc.
  • a polyethylene terephthalate media layer is also shown for comparison purposes, similar to the media layer 208 described above with reference to FIG. 2.
  • the polyester meltblown material has a thickness ranging from 102 –254 ⁇ m (about 4-10 mil) and a unit weight ranging from 22 –40 g/m 2 (Table 1) .
  • the material is electrically charged to enhance particle capture capability.
  • the filtration efficiency for meltblown is measured to be 80 –90%with 0.3 ⁇ m NaCL particles penetrating at a rate 5.3 cm/s. Meanwhile, the airflow resistance recorded in the same test is 14.7 to 19.6 Pa (about 1.5 -2.0 mm H 2 O) .
  • the polyester meltblown material is 65%lighter and 85%thinner.
  • meltblown materials have equal filtration efficiency but a much higher airflow resistance, e.g., 5 times larger than the airflow resistance of electret felt. Based solely on the raw materials properties, it would ordinarily be expected that the polyester meltblown material would have inferior filtration properties compared with the electret felt, particularly in recirculation filtering, due to its significantly reduced air permeability.
  • the polyester meltblown material having a non-uniform fiber size and being substantially free of polypropylene achieves equal or improved particle clean up performance. Without being bound by theory, the meltblown materials possess finer fiber sizes and broader fiber size distributions, which is more attractive to variety of particles sizes traveling at a variety of speeds.
  • FIG. 6 is a side cross-sectional view of an electronic device assembly 600 showing a layered filter assembly 608 as per FIGS. 1-3 installed therein, in accordance with embodiments.
  • the specific device shown is a hard disk drive (HDD) employing the layered filter assembly 608 therein as a recirculation filter inside the electronic device housing 602.
  • the internal components 604 of the electronic device assembly 600 which may include a head disk interface (HDI) , can generate particulates and/or vapors while inducing some amount of recirculation 610 within the interior 606 of the housing 602.
  • the recirculation flow 610 passes through the layered filter assembly 608, where the particulates and/or vapor is captured.
  • Specific performance of layered filter assemblies can be achieved by simulating the end-use environment, e.g., by way of a continuous particle introduction test method.
  • FIG. 7 is a side cross-sectional view of a filtration test assembly and system 700, in accordance with embodiments.
  • the test system 700 can be configured to obtain a particle clean-up performance (PCU) of example recirculation filters and/or vapor clean-up performance (VCU) .
  • PCU particle clean-up performance
  • VCU vapor clean-up performance
  • the test system 700 includes a mass flow controller 702, a test apparatus 704 containing an electronic device enclosure 720, and an analyzer 706 which is under the control of a management component 708, such as a computer controller, which employs a processor 714 and nontransitory memory 716 storing instructions to control characteristics of the respective test.
  • the test system 700 is operable to pass a test contaminant (e.g., particulates, vapor) through a valve 712 and into an injection port 724 of the enclosure 720, and to sample the air inside the enclosure periodically via a sample port 726.
  • a test contaminant e.g., particulates, vapor
  • the mass flow controller 702 under the control of the management component 708, can introduce a stream of particulate-laden air into the electronic device enclosure 720 through an injection port 714.
  • the particulate-laden air will circulate throughout the enclosure 720 where it interacts with a layered filter assembly 722.
  • the particles used were 0.1 um and 0.3 um polystyrene latex spheres (PSL) provided by Thermo Fischer Scientific Inc., which were suspended in water and then aerosolized using a 3076 Aerosol Generator from TSI Inc. The aerosol stream was then dried using a diffusion dryer and drawn into the enclosure 720 through the injection port 724 at a constant flow rate.
  • the particle counter used for this test was a Laser Aerosol Spectrometer 3340 from TSI Inc.
  • the result of the particle clean up test is recorded as T90, which is defined as the time needed to clean up 90%of the particles inside the drive.
  • the second result, relative clean up ratio (RCUR) is recorded as the recorded T90 with a filter over the recorded T90 without a filter.
  • the PCU test results for electret felt (comparative) and polyester meltblown (inventive) samples for a recirculation filter (i.e., a recirculation filter without an adsorbent) similar to the recirculation filter shown in FIG. 1 are shown below in Table 2.
  • the T90 and RCUR values for both the comparative, electret felt example and the inventive polyester meltblown example for a recirculation filter were comparable, indicating that the particle retentive properties of filter assemblies according to the embodiments described herein are similar to the particle retentive properties of the conventional electret felt filters.
  • the polyester meltblown layered filtration assemblies slightly outperformed the conventional electret felt filters despite being significantly thinner, with T90 times on average 2-seconds faster than those of the conventional filter, and improvements in RCUR ratios of 6-7 %.
  • the T90 data for the inventive meltblown example is found to be 13 seconds, while the T90 for a traditional electret felt is 10 -11 seconds.
  • the RCUR data shows the difference between these two filters is less than 10%.
  • Organic vapor breakthrough time can be measured by passing a flow of air containing a predetermined concentration of a volatile organic standard through an adsorbent breather assembly.
  • concentration of the volatile organic standard can be measured in the airflow exiting the adsorbent breather assembly.
  • a common volatile organic standard used for such tests is trimethylpentane (TMP) .
  • a mass flow controller 702 under the control of the management component 708, can alternatively introduce a stream of vapor-containing air into the electronic device enclosure 720 through an injection port 714.
  • the vapor-containing air will circulate throughout the enclosure 720 where it interacts with a layered filter assembly 722 containing an adsorbent layer, similar to the layered filter assemblies 200, 300 shown in FIGS. 2 and 3.
  • the tested layered filter assembly was positioned in the same type of enclosure 720 used for PCU testing as described above.
  • a flow of 30 cc /min of air with 120 ppm of trimethylpentane (TMP) was injected into the enclosure through an injection port 724 in the cover of the enclosure 720. Air samples were drawn from the drive through the sampling port 726.
  • a Gas Chromatographic Monitor (Agilent Technologies Inc. Gas Chromatograph 7820A) together with a data acquisition system was linked with the sampling port 726 and used to obtain an outlet TMP concentration over time.
  • the vapor clean up efficiency is determined as the TMP break through concentration at 3 hours, i.e. a proportion of the outlet TMP concentration over the inlet TMP concentration. The lower the break through concentration, the better the vapor clean up efficiency.
  • FIG. 8 is a chart illustrating the filtration efficiency of a comparative electret felt filter assembly (Comparative Example 804) and an inventive polyester meltblown layered filter assembly (Example 1, 802) .
  • the chart shows that both example filter assemblies possess VCU efficiencies near 10 % (approaching 9.7 %for the comparative example at 3 hours, approaching 11.7 %for Example 1) .
  • the VCU test illustrates that the layered filter assembly using the polyester meltblown filtration layer can achieve comparable VCU efficiencies to a conventional electret felt-based filtration assembly, despite being significantly thinner.
  • a layered filter assembly comprising a filtration layer comprising a polyester comprising fibers having a non-uniform fiber size ranging from 0.1 ⁇ m to 10 ⁇ m; and one or more porous support layers adjacent to the filtration layer.
  • non-polypropylene meltblown polymer comprises fibers having two or more average fiber sizes including a first subset of fibers having average diameters of 0.1 ⁇ m to 3 ⁇ m and comprising at least 85 %of the fibers.
  • non-polypropylene meltblown polymer comprises a second subset of fibers having average diameters from 3 ⁇ m to 5 ⁇ m and comprising 15 %of the fibers.
  • the layered filter assembly of any of the preceding or subsequent examples further comprising one or more thermal melt adhesive layers, wherein the one or more thermal melt adhesive layers join the filtration layer with the one or more porous support layers.
  • the layered filter assembly of any of the preceding or subsequent examples further comprisingan adsorbent layer; and a media layer, wherein: the adsorbent layer is positioned between the filtration layer and the media layer; and the one or more porous support layers adjacent to the filtration layer and the media layer on an opposite side of the adsorbent layer.
  • E27 The layered filter assembly of any of the preceding or subsequent examples wherein the media layer is a nonwoven polyester formed by one of a carding, spunbond, or meltblown process.
  • An article for filtering an enclosure comprising a housing for retaining an electronic device; and a layered assembly arranged inside the housing, the layered assembly comprising: a filtration layer comprising a polyester layer comprising fibers having a non-uniform fiber size ranging from 0.1 ⁇ m to 10 ⁇ m; and one or more porous support layers adjacent to the filtration layer.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Filtering Materials (AREA)
  • Electrostatic Separation (AREA)

Abstract

On décrit un ensemble filtres en couches qui peut comprendre une couche filtrante et une ou plusieurs couches de support poreuses adjacentes à la couche filtrante. La couche filtrante peut être formée de polyester avec des tailles de fibres non uniformes allant de 0,1 micron à 10 microns.
PCT/CN2017/074345 2017-02-22 2017-02-22 Ensemble filtres en couches pour protection d'enceinte WO2018152683A1 (fr)

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