Note: Descriptions are shown in the official language in which they were submitted.
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~ I Various gas phase filters have been described
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`~ 20 in the patent literature. U. S. patent 3,645,072 shows
~ a granular activated carbon filter within a frame of
i~ I U-shaped channels. The bonded activated carbon body
;~ may be reinforced with a wire or other network. U. S.
patent 3,630,007 teaches a disposable activated charcoal
; filter having a frame open at both sides and subdividea
into~a plurality of compartments by intersecting parti-
*ions. U. S. patent 3,350,860 teaches granular activated
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, ) carbon poured into filter cont~iners. U. S. patent
3,474,600 teaches activated carbon particles bonded
together by monnolefin polymers to form pellets and the
pellets are then bonded to each other by the polymer
to form larger shapes. U. S. patent 2,544,733 teaches
a filter for removing o~orous qualities from gasses
containing a rigia outer frame and an multiplicity of
spaced flexible webs carried within said frame and a
plurality of layers of granular odor-adsorbing material
carried between and substantially filling the spaces
between said webs. The granules of odor-adsorbing mate-
rial being adhesively united to adjacent surfaces of
` ( said webs by means of tapes to prevent relative displace-
; ment of said granules with respect to said webs. U. S.
patent 3,577,710 teaches reactant pellets placed in a
honeycomb sheet structure and retained therein by foam
rubber or plastic cover sheets. U. S. patent 3,870,~95
teaches non woven laid fibers used in air filters. U. S.
patent 3,721,072 teaches a filter for removing odors
comprised of granules bonded together in a monolithic
extended surface shaped in the form of a wave. U. S.
patent 3,873,287 teaches the construction of assemblies
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of granular material filled adsorbers nr filters for
fluids using modular c~mponents readily standardi~ed
to ~acilitate assembly of a variety of filter unit sizes
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- ~ Su~mary of the Invention
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It is an object of the present invention to
manufactùre gas phase permeable filters by a quick and
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convenient method, specifically adhesively securing particulate
gas phase odor-removing means to a substrate or grid.
In one particular aspect the present invention provides
the method of making a gas phase permeable filter comprising
the steps:
1) providing a self-supporting perforated sheet-like
substrate;
2) applying an adhesive to a face of the substrate
without materially adversely affecting the permeability of
the substrate;
3) applying a uniform layer of particulate gas phase
odor-removing media in the form of individually discrete
particles to the adhesive coated face of the substrate with
, only a minor portion of the surface of the particulate media
in contact with the adhesive and a ma;or portion upstanding
from the face of the substrate and free of contact with any
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:~ adhesive;
.'~ 4) treating the adhesive to adhere the particulate
media to the substrate; :
5) assembling portions of the thus coated substrate in
~j: confronting face-to-face relation with the particulate media
,J~ covered faces in opposed juxtaposition and the particulate
media upstanding from the coated faces of the substrates to
space the confronting substrate portions apart and
6) mounting a frame about the peripheral edges of the
` confronting substrate portions to integrate such substrate
portions in a f ilter.
In another particular aspect the present invention
` provides the method of making a gas phase permeable filter
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comprising the steps:
1) providing a plurality of self-supporting perforated
sheet-like substrates;
2) adhesively bonding to one face of two substrates a
uniform layer of particulate gas phase odor-removing media
with only a minor portion of the surface of the particulate
media in contact with the adhesive and a major portion
upstanding therefrom free of adhesive;
. 3) adhesively bonding in like fashion to both faces of
another substrate uniform layers of particulate gas phase
odor-removing media;
4) assembling the substrates with the first-mentioned
substrates having the particulate layers in confronting
relation and the last-mentioned substrate sandwiched therebetween
', in non-adhesively bonded relation; and
5) securing the assembled substrates in a fixed assembly.
In yet another particular aspect the present invention
provides a gas phase permeable filter comprising:
a plurality of self-supporting perforated sheet substrates
arranged in confronting spaced apart face-to-face relation
having discrete perforations,
8 means for holding said substrates in the aEoresaid
assembled relation,
a uniform layer of particulate odor-adsorbing media
disposed in the space between said substrates,
said layer consisting essentially of discrete odor-
removing particles ranging in size from approximately 12/28
to 4/6 measured by the Tyler screen series individually
adhesively bonded to one of the confronting substrate faces
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'-'``such that the layer is held between the spaced apart substrates
against settling or displacement, and
each odor-removing particle having only a minor portion
of its surface in contact with the adhesive and a ma;or
portion upstanding from the substrate face and free of
adhesive.
In a further particular aspect the present invention
provides a gas phase permeable filter comprisin'g:
, .,
J a plurality of self-supporting perforated sheet substrates
assembled in confronting spaced apart face-to-face relation
having discrete perforations, each of said confronting faces
having disposed upon it a uniform layer of odor-adsorbing
media consisting essentially of discrete odor-removing
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~ particles individually bonded by adhesive to its adjacent
,0~ confronting face such that the layer is held between the
spaced apart substrates against settling and displacement,
~ each odor-removing particle having only a minor portion of
;' its surface in contact with the adhesive and a major portion
~` , upstanding from the substrate face and free of adhesive so
to form a thickness of odor-removing media between the
substrates of approximately two particulate diameters; and
a means for holding said su,bstrates in the aforesaid
` assembled relation.
Brief Description of the Drawings
Fig. 1 shows a plan view of the gas phase fil~er of the
present invention in a final assembled condition;
. .
Fig. 2 is a schematic drawing showing the manufacture of
the filter of Fig. l;
Fig. 3 is a cut away of the filter of Fig. l;
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"~ Fig. 4 is a filter of the present invention having a
backing of a grease, dust and smoke and other particulate
removal means such as a glass fiber batt;
Fig. 5 shows a filter obtained by use of a single grid
or substrate that has been spirally wound or rolled to a
desired shape with particulate gas phase odor-removing means
adhered to both faces of the substrate;
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Fig. 6 is cross-sectional view taken on the line
6-6 of Fig. 5;
Fig. 7 shows a filter similar to Fig. 1 except
one substrate is a fiber glass ba-tt or the like;
Fig. 8 is another embodiment of the present
invention wherein the grid or substrate of the filter is a
laminate such as paper and metal;
Fig. 9 is a fragmentary cross-sectional perspective
similar-to Fig. 1 but shows an intermediate grid between the
- 10 two outer sheets with particulate gas phase odor-removing
means adhesively secured to opposite faces thereof.
Description of Prefer ed Embodiments
The gas phase permeable filter such as an air
filter is manufactured by the following steps:
1. Providing a gas phase permeable substrate having
opposite surfaces;
2. Applying an adhesive to one or both surfaces
of the substrate;
3. Applying particulate gas phase odor-removing
means to the adhesively coated faces of the substrate;
4. Drying the adhesive; and
5. Assembling the substrate in a desired filter
configuration wherein the inner surface of the filter is a
surface of the substrate coa-ted with the particulate gas
phase odor-removing means and the outer surface of the filter
is a surface of the substrate uncoated with the particulate
means.
There are numerous applications in the home, such
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as ductless range hoods, room air purifiers, electronic air
cleaners, air conditioners, and heating, ventilating systems.
Normally the odors to be removed are those generated by human
activities and include cooking and smoking, or odors from pets
or other animals, or human waste.
In addition, there may be more stringent filtering
requirements such as commercial/industrial applications, where
fuel exhaust tairports or power plants) and/or manufac-turing
operations generate specific, and in many cases concentrated
odorants which may not only be objectional, but may be also
toxic, i.e., sulfer dioxide, formaldehyde, phenols, and the
like. In order to remove specific odors, appropriately
designed, impregnated, or selected gas phase odor-removing
means may be employed, with or without the use of a means
I for removing smoke, dust, or other particulates.
; The gas phase odor-removing means ma~ be any
particulate substance, such as flakes, particles, pellets or
granules. Generally the particles have a range in size from
12/28 to 4/6, preferably 6/8 mesh measured by either U.S. or
Tyler screen series. The filtering means itself, that is the
gas phase odor-removing means, may be activated carbon, havin~
a pelletilized, flake, or granulated size and shape, and may
be obtained from a supplier such as Union Carbide Corporation,
or it may be Purafil (Trademark of H. E. Burroughs and
Associates for potassium permanganate impregnated activated
alumina), or it may be Sanilan (Trademark of Collo G.M.b.H.
of West Germany for a chemisorptive filter medium in
pellitized form.l These particulate mate~ials may be impregnated
with appropriate counteracting materials to the odor-producing
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substances present in the gas phase which one wishes to
purify. For example, there may be an appropriate impregnant
in activated carbon, for example to combat the sulfur dioxide,
formaldehyde or phenol substances presen-t in the gas phase that
one wishes to purify.
The grid or substrate that is used in the present
application can be made of a variety of substances. It may be
made of appropriate metallic elements such as aluminum, or
tin-plated cold-rolled ste~l, a laminate of paper or paper and
metal such as aluminum foil, or a paper substance upon which has
been sprayed or applied a reinforcing or strong-adhering
coating such as a metallic backing. All that is required for
the substrate is that it have appropriate porosity and be stable
in the environment in which the filter is used. The substrate
should be capable of allowing the gas phase to be filtered to
pass freely therethrough. In the case of sheet-like substrates
the sheets may be perforated to have an open area as low as
20 percent and a high of about 65 percent, preferably about
45 percent. This should be accomplished by having a substrate
having holes of a diameter less than the size of the particulate
media. The substrate shown in a preferred embodiment may range
from 0.012" - 0.040" in thickness.
The adhesive that may be applied to the substrate
prior to the application of the particulate gas phase odor-
adsorbing substance to adhere the same to the subs-trate would
be any adhesive which could conveniently and securely bond the
filtering particles to the substrate. The adhesive must be
a strong adhesive and must be one that does not substantially
surround the filtering particles itself because the adhesive
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may then decrease substantially the efectiveness of the
filtering medium such as the activated charcoal. In addition,
the adhesive must be stable in the environment of the medium
in which the filter is used as well as retain its adhering
properties to retain securely the particles thereto. Preferably,
the adhesive is one that may be tacified by the application
of heat to increase the drying of the adhesive.
The most preferred adhesive is one sold by 3M and
identified as laminating adhesive PB-4236 which is a water
dispersion containing 47 percent solids content and is a soft
gel primarily polychloroprene-based substance weighing about
9.1 pounds per gallon and having a viscosity of approximately
3,000 cps.
The adhesive must be applied to the substrate in
such manner as to avoid unwanted seepage through the holes to
the opposite face of the substrate. Preferably, it is roll
coated onto the substrate to ensure uniform application thereto
of approximately 1 mil thickness. The adhesive must be capable
of withstanding the appropriate temperatures of the gas phase
application such as being stable up to approximately 300F.
The adhesive is one that should be capable of drying in a
relatively short period of time. Additionally, the adhesive
should be applied such that it does not fill the holes in the
substrate thereby decreasing its porosity.
Turning now to a discussion of the drawings, Fig. 1
shows filter 10 of the present invention having a pair of spaced
apart perforated grids 11 and 12 each having holes 13
therethrough retained in a U-shaped channel frame 14. The
frame may comprise a single U-shaped channel bent at the four
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corners and locked at the meeting ends by locking tab 16,
conventional in filter frame construction. Between the grids
11 and 12 and holding them in spaced apart relation as shown
in Fig. 3 is particulate gas phase odor-removing means 35.
The filter 10 is manufactured accordinq to Fig. 2.
Roll stock 18 of the perforated substrate is fed to a cutter
20. The substrate cut to size is passed onto a continuous belt
22 maintained between rolls 24 and 26. Adhesive from reservoir
28 is applied by roll coater 30 to the cut grid. A drying oven
32 is stationed above the adhesively treated grid 18a and
tacifies the adhesive by subjecting the grid to tacifying
temperatures such as 160F. Thereafter, and before the
adhesive hardens, a uniform layer of gas phase removing particles
' 35 are deposited from tank 34 onto the tacified grid. Because
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the adhesive dries very quickly the grid with the adhesively
secured particles may be handled at the end of the continuous
belt at station 36. Desirably, following removal of the
substrate at station 36, it is inverted and shaken to remove
excess, non-adhered particles. The filter 10 of ~ig. 1 is
obtained by assembling two grids from station 36 by placing
one on top of the other with the inner surfaces of the grids
facing each other as shown at 38. The two grids are then
assembled in the U-shaped frame 14 as best shown in Fi~. 3.
.
'' It is important that the adhesive be 9uf~iciently
~ tacified by the oven 32 that when the particulate material is
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~ deposited thereon at 34, the adhesive will not appreciably
',"~ capilate into the particulate material and materially reduce its
, ~ effectiveness. At the same,time the adhesive must not have so
far set up as to prevent the particulate material from settling
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into it in bonding contact therewith.
With the grids assembled as shown in Fig. 3. (and
also Fig. 4) the granules or pellets 35 adhered to the grids are
disposed in abutting contact. The entire surface areas of the
particulate material except for the small areas in contact with
the adhesive on the grids are free to adsorb the odors from
the gas phase passed through the filter. The abutting contact
of the particles 35 serves to space the substrates 11 and 12
apart.
The U-shaped frame may be manufactured from appro-
priately shaped metallic or may be lightweight plastic such
as polyvinyl chloride or other plastics which are not suseptible
to corrosion in the environment in which the filter will be used.
In a modified form of the Fig. 1 and 3, filter, a
batt of loosely matted glass fibers 40 or other suitable non-
woven material may overlie the outer face of grid 11 as shown
in Fig. 4. The glass fiber batt will enhance the grease, dust,
smoke and other particulate removal capability of the filter.
It is held in place against substrate 11 by adhesive bonding
thereto. The adhesive is preferably applied to the substrate
~ and before drying the batt is juxtaposed thereagainst. The
b' channel frame 14 overlies the edges of the batt ~urther
- retaining same against the substrate.
In Figs. 5 and 6 a filter of cylindrical shape is
shown. It is formed by spirally winding a perforated substrate
coated on one but preferably both sides with a uniform layer of
particulate odor-absorbing medium 44. The substrate with the
adsorbing particles is spirally wound upon itself to form a
hollow central tube 59 into which air or other gas to be filtered
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is introduced at a central gas entering aperture 60. The gas
then passes radially outwardly as indicated by the arrows in
Fig. 6. A closure cap 62 overlies one end of the filter and
an annular cap 64 overlies the opposite end and defines the
central gas entering aperture.
In constructing the filter of Figs. 5 and 6 a length
of perforated substrate 66, such as a flexible laminate of
paper having aluminum foil bonded to opposite faces, is coated
with an adhesive on both faces and the odor-removing means is
then uniformly deposited on the coated faces. End portions
of the substrate which when wound into the spiral shape will
define the exposed wall 65 of the central tube 59, as well as
the outex surface 68 of the filter, are left uncoated so that
the aluminum foil surface is exposed. Also, if desired, the
aluminum foil may cover only those surfaces of the substrate
which will be exposed as aforesaid, the remaining surfaces of
~; the substrate being the paper itself with the particulate
odor-absorbing media bonded thereto. Where the inner and
outer ends 70 and 72 of the spiral wrap lap adjacent convolutions,
the ends may be adhesively secured or stapled thereto.
Alternatively, if desired, a length of perforated
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paper substrate may be coated on both faces and the odor-
adsorbing media adhered thereto and then the paper wound into
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substrate of paper and aluminum foil having the odor-adsorbing
media bonded to the inside of the tube and the foil exposed on
the ouside may be slipped over the spiral ~orm. A similar but
smaller tube with the foil on the inside and media bonded to the
outside may be inserted into the center of the spiral, and the
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hole then closed at opposite ends with caps similar to 62 and 64.
The construction of Figs. 5 and 6 represent a
substantial improvement over the prior ar-t wherein a filter formed
by concentric tubes having end caps similar to 62 and 64 is simply
filled with loose carbon particulate or similar material because
the weight is reduced, air flow improved, the odor-adsorbing media
will not settle, and the filter will not bleed carbon fines through
the holes.
A further modification of the filter of Figs. 1 and
3 is shown in Fig. 7 wherein the grid 11 is omitted and in its
place a glass fiber or similar batt 72 is substituted. llhe grid
12, with adhesively bonded odor-adsorbing particles 35, is
manufactured as above described. The batt 72 has one surface
sprayed or otherwise applied with adhesive and then such surface,
following tacification, is juxtaposed against the odor-adsorbing
particles 35. Upon curing of the adhesive the batt is retained in
place.
The grids or substrates above mentioned may be
all metal, or may be a laminate of a cellulosic material such
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as paper 52 and metal 54 such as aluminum foil as shown in
Fig. 8. This substrate may be processed by applying adhesive
42 to the paper surface and particles 35 then deposited thereon.
`~ A filter resultin~ from the substrate adhesively secured
particles of Fig. 8 is extremely light-weight and the metal
~ foil acts to strengthen the laminate and protect the paper
-j and as a reflec-tive insulator and provide a decorative finish.
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The adhesive is roll-coated to the paper side of the substrate
and the odor-removing particles 35 applied thereto as above
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described. The alunimum foil may, if desired, be on both
faces of the paper sheet. However, it has been found that
the adhesive applied by roll coating will tend to be absorbed
to some extent by the paper and act as a protective layer
thereon obviating the use of foil on -the inside surface of
the filter.
In Fig. 9 a filter is shown which includes three
grids, 80, 82 and 84. Grids 80 and 84 are similar to grids 11
and 12 of Figs. 1 and 3. Grid 82 may comprise either a
perforated metal or paper or paper/aluminum foil laminate,
on opposite faces of which is adhesively fixed uniform layers
; 86 and 88 of particulate odor~adsorbing media. The grid 82
with opposite faces exhibiting the particulate media is
sandwiched between the grids 80 and 8~ and the composite
enclosed in a frame 90 similar to the Figs. 1 and 3 structure. `
This construction substan-tially doubles the efficiency and
life of the filter as compared with the construction of Figs.
1 and 3.
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