U.S. patent application number 12/036022 was filed with the patent office on 2009-02-26 for formed filter element.
Invention is credited to Eugene F. Dunn, III, Joseph Israel.
Application Number | 20090050578 12/036022 |
Document ID | / |
Family ID | 39683989 |
Filed Date | 2009-02-26 |
United States Patent
Application |
20090050578 |
Kind Code |
A1 |
Israel; Joseph ; et
al. |
February 26, 2009 |
FORMED FILTER ELEMENT
Abstract
A filter medium for use in filtering a mobile fluid made from at
least a bicomponent fiber. Other fibers, particles, or other
materials can also be entrained in the filter medium. The filter
medium has a substantial thickness compared to filters of the prior
art. The fiber length and diameter dimensions are selected to
obtain desired filter characteristics including thickness, basis
weight, pore size, filtration efficiency, pressure drop, burst
strength, and manufacturing efficiency. Further, a multilayer
filter medium can be provided with ease. Each layer can have a
different composition, pore size, basis weight, and so forth, thus
providing the ability to build multiple functionality into the
filter media of the invention.
Inventors: |
Israel; Joseph; (St. Louis
Park, MN) ; Dunn, III; Eugene F.; (Coon Rapids,
MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
39683989 |
Appl. No.: |
12/036022 |
Filed: |
February 22, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60903179 |
Feb 23, 2007 |
|
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Current U.S.
Class: |
210/767 ;
210/508; 427/203; 55/524; 95/273; 95/285 |
Current CPC
Class: |
B01D 2239/1241 20130101;
B01D 2239/1225 20130101; B01D 39/2048 20130101; B01D 2239/0407
20130101; B01D 2239/064 20130101; Y10T 29/49826 20150115; B01D
39/1615 20130101; B01D 2239/025 20130101; B01D 2239/1233 20130101;
B01D 39/2089 20130101; B01D 39/2065 20130101; B01D 2239/0216
20130101; B01D 39/2058 20130101; B01D 39/2062 20130101; B01D
2239/086 20130101; B01D 39/163 20130101; B01D 39/2024 20130101 |
Class at
Publication: |
210/767 ; 55/524;
95/273; 95/285; 210/508; 427/203 |
International
Class: |
B01D 39/14 20060101
B01D039/14; B01D 46/00 20060101 B01D046/00; C02F 1/00 20060101
C02F001/00; B05D 3/02 20060101 B05D003/02 |
Claims
1. A filter medium comprising: a bicomponent fiber; and a particle,
the particle comprising at least one of a metal oxide, a metal, a
ceramic, a zeolite, a carbon, an ion exchange resin, or a nanotube,
wherein the filter medium has a basis weight at least about 500
gram/meter.sup.2, a permeability of about 0.5 to 200 fpm inclusive,
a thickness equal to or greater than 8 millimeters, and a solidity
of less than about 25%.
2. The filter medium of claim 1, wherein the bicomponent fiber is
about 20 to 95 wt % inclusive of the filter medium.
3. The filter medium of claim 2, further comprising, about 80 to 5
wt % inclusive of a glass fiber having a fiber diameter of about
0.1 to 8.0 microns inclusive and aspect ratio of greater than about
1:100.
4. The filter medium of claim 3 wherein the filter medium has a
thickness greater than about 5 centimeters.
5. The filter medium of claim 3 wherein the bicomponent fiber has a
diameter of about 5 to 50 micrometers inclusive and a length of
about 0.1 to 20 millimeters inclusive.
6. The filter medium of claim 3 wherein the bicomponent fiber has a
diameter of about 10 to 20 micrometers inclusive and a length of
about 0.2 to 15 millimeters inclusive.
7. The filter medium of claim 3 wherein the bicomponent fiber
comprises a core material disposed within a sheath material.
8. The filter medium of claim 7 wherein the core material has a
higher melting point than the sheath material.
9. The filter medium of claim 8 wherein the core material has a
melting point of about 200.degree. C. to 260.degree. C. inclusive
and the sheath material has a melting point of about 80.degree. C.
to 200.degree. C. inclusive.
10. The filter medium of claim 7 wherein the sheath material
comprises a polyolefin, a polyester, a polyvinyl acetate, a
polyvinyl chloride, a polyvinyl butyral, an acrylic resin, a
polyamide, a polyvinylidene chloride, a polystyrene, a polyvinyl
alcohol, a polyurethane, a cellulosic resin, a styrene-butadiene
copolymer, an acrylonitrile-butadiene-styrene copolymer, a
KRATON.RTM. rubber available from Kraton Polymers U.S. LLC of
Houston, Tex., or a copolymer blend or a mixture thereof.
11. The filter medium of claim 3, further comprising a binder.
12. The filter medium of claim 11 wherein the binder is a
latex.
13. The filter medium of claim 11 wherein the binder comprises an
acrylic, ethylene vinyl acetate, a polyvinyl alcohol, an ethylene
vinyl alcohol, a polyvinyl pyrrolidone, a polyvinyl chloride, or a
copolymer or a blend thereof.
14. The filter medium of claim 11 wherein the binder is solvent
borne.
15. The filter medium of claim 14 wherein the binder comprises a
phenolic resin, a polyvinyl acetate, a polyvinyl alcohol, an
acrylic resin, a methacrylic resin, a polyurethane, a
polycyanoacrylate, an epoxy, a melamine resin, a polycaprolactone,
or a blend or a copolymer thereof.
16. The filter medium of claim 3, further comprising a
thermoplastic fiber.
17. The filter medium of claim 16 wherein the thermoplastic fiber
comprises a polyester, a polyamide, a polypropylene, a
copolyetherester, a polyetherketoneketone, a polyetheretherketone,
a liquid crystalline polymer, or a copolymer or a mixture
thereof.
18. The filter medium of claim 17 wherein the thermoplastic fiber
comprises a polyester comprising poly(ethylene terephthalate).
19. The filter medium of claim 3 further comprising an antioxidant,
a stabilizer, a lubricant, a toughener, a dispersing aid, a binder,
a surface active agent, an acid, a catalyst, or a mixture
thereof.
20. The filter medium of claim 3 further comprising an inorganic
fiber.
21. The filter medium of claim 20 wherein the inorganic fiber
comprises a carbon, a metal, a metal oxide, or a combination
thereof.
22. The filter medium of claim 3 further comprising a fiber
comprising one or more naturally occurring cotton, linen, wool,
cellulosic or proteinaceous polymers.
23. The filter medium of claim 3 wherein the particle is the
carbon, the carbon comprising activated charcoal.
24. The filter medium of claim 3 wherein the particle has an
average particle size of 3 millimeters or less.
25. The filter medium of claim 3 wherein the filter medium has an
average pore size of 0.1 to 50 micrometers inclusive.
26. The filter medium of claim 3 wherein the filter medium has an
efficiency of greater than about 50% as measured by ASTM-1215-89
using 0.78.mu. monodisperse polystyrene spherical particles at 20
fpm.
27. The filter medium of claim 3 wherein the filter medium has a
Di-octyl Phthalate (DOP) efficiency in filtering 2 .mu.m aerosol
particles of at least about 95%.
28. The filter medium of claim 3 wherein the filter medium has a
burst strength of at least 10 psid.
29. The filter medium of claim 3 wherein the filter medium has a
tensile strength of at least 20 psi and an elongation at break of
between about 1.0 and 10.0%.
30. The filter medium of claim 3 wherein a pressure drop across the
filter medium at 60 psi applied air pressure is less than about 2.0
psi after 200 hours of filtration at 60 psi of air containing oily
particles.
31. The filter medium of claim 3 wherein a pressure drop across the
filter medium at 60 psi applied air pressure is less than about
10.0 psi after 8000 hours of filtration at 60 psi of air containing
oily particles.
32. The filter medium of claim 3 wherein an oil carryover is less
than about 2.0 ppm after 1000 hours of filtration at 60 psi of air
containing oily particles.
33. The filter medium of claim 3 wherein an oil carryover is less
than about 3.0 ppm after 4000 hours of filtration at 60 psi of air
containing oily particles.
34. The filter medium of claim 3 wherein an oil carryover is less
than about 5.0 ppm after 8000 hours of filtration at 60 psi of air
containing oily particles.
35. The filter medium of claim 3 wherein a discharge temperature is
less than about 93.degree. C. after 8000 hours of filtration at 60
psi of air containing oily particles.
36. The filter medium of claims 2 further comprising about 80 to 5
wt % inclusive of a first glass fiber having a diameter of about
0.1 to 8.0 microns inclusive and a second glass fiber having a
fiber diameter of about 8.0 to 13.0 microns inclusive.
37. The filter medium of claim 2 further comprising about 80 to 5
wt % inclusive of a first glass fiber having a diameter of less
than about 1.0 micron and a second glass fiber having a diameter of
more than 1.0 micron.
38. The filter medium of claim 2 further comprising about 80 to 5
wt % inclusive of a first glass fiber having a diameter of about
0.1 to 2.0 microns inclusive and a second glass fiber having a
fiber diameter of about 2.6 to 8.0 microns inclusive.
39. The filter medium of claim 2 further comprising about 80 to 5
wt % inclusive of a first glass fiber having a diameter of about
0.5 to 0.8 microns inclusive and a second glass fiber having a
diameter of about 2.6 to 3.0 microns inclusive.
40. A process to form a filter medium, comprising the steps of:
blending a first mixture of fibers comprising a bicomponent fiber
to form a first aqueous slurry; applying the first aqueous slurry
to a support to form a first wet layer; removing sufficient water
from the first wet layer to make a first formed layer; blending a
second mixture of fibers to form a second aqueous slurry, wherein
the composition of the second mixture of fibers differs from the
composition of the first mixture of fibers; applying the second
aqueous slurry to the first formed layer to form a second wet
layer; removing sufficient water to form a second formed layer; and
heating the first and second formed layers to a temperature
sufficient to melt one component of the bicomponent fiber.
41. The process of claim 40 wherein the water is removed from the
first and second wet layers by a vacuum means.
42. The process of claim 40 wherein the fibers are substantially
dried during the heating step.
43. The process of claim 40 wherein one or more of the first and
second mixture of fibers comprises about 20 to 95 wt % inclusive of
a bicomponent fiber; and about 80 to 5 wt % inclusive of a glass
fiber.
44. The process of claim 43 wherein the glass fiber has a diameter
of about 0.1 to 8.0 microns inclusive and aspect ratio of greater
than about 1:100.
45. The process of claim 43 wherein the glass fiber comprises a
first glass fiber having a diameter of about 0.1 to 8.0 microns
inclusive and a second glass fiber having a fiber diameter of about
8.0 to 13.0 microns inclusive.
46. The process of claim 43 wherein the glass fiber comprises a
first glass fiber having a diameter of about 0.1 to 2.0 microns
inclusive and a second glass fiber having a fiber diameter of about
2.6 to 8.0 microns inclusive.
47. The process of claim 40 wherein the filter medium after the
heating step has a thickness equal to or greater than 8
millimeters.
48. The process of claim 40 wherein the filter medium after the
heating step has a thickness greater than about 5 centimeters.
49. The process of claim 40 wherein the bicomponent fiber has a
diameter of about 5 to 50 micrometers inclusive and a length of
about 0.1 to 20 millimeters inclusive.
50. The process of claim 40 wherein the bicomponent fiber comprises
a core material disposed within a sheath material, the core
material having a melting point of about 200.degree. C. to
260.degree. C. inclusive and the sheath material having a melting
point of about 80.degree. C. to 200.degree. C. inclusive.
51. The process of claim 50 wherein the sheath material comprises a
polyolefin, a polyester, a polyvinyl acetate, a polyvinyl chloride,
a polyvinyl butyral, an acrylic resin, a polyamide, a
polyvinylidene chloride, a polystyrene, a polyvinyl alcohol, a
polyurethane, a cellulosic resin, a styrene-butadiene copolymer, an
acrylonitrile-butadiene-styrene copolymer, KRATON.RTM. rubbers
available from Kraton Polymers U.S. LLC of Houston, Tex., or a
copolymer or a mixture thereof.
52. The process of claim 40, further comprising adding a binder to
one or more of the first and second aqueous slurries.
53. The process of claim 52 wherein the binder is a latex binder,
the latex binder comprising an acrylic, an ethylene vinyl acetate,
a polyvinyl alcohol, an ethylene vinyl alcohol, a polyvinyl
pyrrolidone, a polyvinyl chloride, or a copolymer or a blend
thereof.
54. The process of claim 52 wherein the binder is solvent borne,
the binder comprising a phenolic resin, a polyvinyl acetate, a
polyvinyl alcohol, an acrylic resin, a methacrylic resin, a
polyurethane, a polycyanoacrylate, an epoxy, a melamine resin, a
polycaprolactone, or a copolymer or blend thereof.
55. The process of claim 40, further comprising adding a
thermoplastic fiber to one or more of the first and second aqueous
slurries, the thermoplastic fiber comprising a polyester, a
polyamide, a polypropylene, a copolyetherester, a polyethylene
terephthalate, a polybutylene terephthalate, a
polyetherketoneketone, a polyetheretherketone, a liquid crystalline
polymer, and mixtures thereof.
56. The process of claim 55 wherein the thermoplastic fiber
comprises a polyester comprising poly(ethylene terephthalate).
57. The process of claim 40 further comprising adding an
antioxidant, a stabilizer, a lubricant, a toughener, a dispersing
aid, a surface active agent, an acid, a catalyst, or a mixture
thereof.
58. The process of claim 40 further comprising adding an inorganic
fiber to one or more of the first and second aqueous slurries, the
inorganic fiber comprising a carbon, a metal, a metal oxide, or a
combination thereof.
59. The process of claim 40 further comprising adding a fiber to
one or more of the first and second aqueous slurries, the fiber
comprising one or more naturally occurring cotton, linen, wool,
cellulosic or proteinaceous polymers.
60. The process of claim 40 further comprising adding a particle to
one or more of the first and second aqueous slurries, the particle
comprising a metal oxide, a metal, a ceramic, a zeolite, a carbon,
an ion exchange resin, a nanotube, or a mixture thereof.
61. The process of claim 60 wherein the particle is the carbon, the
carbon comprising activated charcoal.
62. The process of claim 60 wherein the particle has an average
particle size of 3 millimeters or less.
63. The process of claim 40, further comprising adding an additive
to one or more of the first and second slurries after the heating
step, the additive comprising a surface finish compound, a compound
to change the surface energy of one or more fibers, an acid, a
base, a fluorocarbon, a flame retardant compound, a catalyst, an
antistatic compound, or a combination thereof.
64. The process of claim 63 wherein the additive is added by means
of dipping the filter medium in a solvent having the additive
dispersed therein.
65. The process of claim 63 wherein the additive is added by a
spraying means.
66. The process of claim 40, further comprising adding an additive
to one or more of the first and second slurries, the additive
comprising a surface finish compound, a compound to change the
surface energy of one or more fibers, an acid, a base, a
fluorocarbon, a flame retardant compound, a catalyst, an antistatic
compound, or a combination thereof.
67. The process of claim 40, further comprising heating the first
formed layer prior to applying the second aqueous slurry to the
first formed layer.
68. A method of removing an impurity from a fluid stream
comprising: contacting a stream containing an impurity with a
filter medium comprising a bicomponent fiber, wherein the filter
medium has a basis weight at least about 500 gram/meter.sup.2, a
permeability of about 0.5 to 200 fpm inclusive, a thickness equal
to or greater than 8 millimeters, and a solidity of less than 25%;
and passing the stream through the filter medium such that the
impurity is removed from the fluid stream.
69. The method of claim 68 wherein the filter medium comprises a
particle of at least one of metal oxide, a metal, a ceramic, a
zeolite, a carbon, an ion exchange resin, or a nanotube.
70. The method of claim 68 wherein the filter medium has a
thickness of greater than 5 centimeters.
71. The method of claim 68 wherein the stream is a gas or a
liquid.
72. The method of claim 71 wherein the stream is the gas and the
gas is air.
73. The method of claim 71 wherein the stream is the liquid and the
liquid is water.
74. The method of claim 68 wherein the stream comprises gasoline,
diesel fuel, motor oil, or a combination thereof.
75. The method of claim 68 wherein the impurity is a particle.
76. The method of claim 75 wherein the impurity particle comprises
dust, soot or smoke.
77. The method of claim 75 where the impurity particle is an
aerosol.
78. The method of claim 77 wherein the aerosol is an oil.
79. The method of claim 77 wherein the aerosol is aqueous.
80. The method of claim 77 wherein between about 700 and 20,000 ppm
of the aerosol per million parts by volume of the stream is present
in the stream prior to contact with the filter medium.
81. The method of claim 68 wherein the impurity is a compound.
82. The method of claim 81 wherein the compound comprises a toxin,
a carcinogen, a teratogen, a mutagen, or a lachrymator.
83. The method of claim 68 wherein the stream passes through the
filter medium at a rate of 0.5 to 200 fpm inclusive.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application Ser. No. 60/903,179, filed Feb. 23, 2007 and is
hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a filter element that can be used
for general filtration. One filtration application is removing a
liquid or solid particulate from a mobile fluid and methods of
manufacturing the element. In one embodiment of the invention, the
filter element is used to remove an oily or aqueous/oil liquid
aerosol or particulate entrained in a gaseous or air mobile fluid.
In such an embodiment, the aerosol entrained in the fluid contacts
the media, coalesces, and drains from the media leaving the mobile
fluid free of the entrained liquid aerosol particulate. The liquid
accumulates in the media and under the effect of gravity, drains
from the element and can be reserved.
BACKGROUND OF THE INVENTION
[0003] Cellulosic, synthetic and mixed cellulosic synthetic media
in the form of a flexible paper filter have been known for many
years. Such media layers have been used as is and have been
combined with other filter components to form active filtration
elements. Such elements can be made of a variety of macro and
microfibers having a range of fiber lengths and diameters. In large
part, these layers are made in papermaking machines resulting in a
substrate layer typically less than 5 millimeters and most often
less than 2 millimeters in thickness. Such thin flexible filter
media have found a number of useful applications, however, such
layers have limits in their applicability. The ability to achieve
certain filtration attributes such as pore size, basis weight,
thickness, permeability and efficiency are limited by the
manufacturing techniques used to make the paper layers and by the
components useful in such layers.
[0004] Because aerosols, as an example, may be as small as 1 nm
diameter or as large as 1 mm (W. Hinds, Aerosol Technology:
Properties, Behavior, and Measurement of Airborne Particles 8,
2.sup.nd ed., .COPYRGT. 1999 J. Wiley & Sons), conventional
technologies are not suitably flexible to effectively accommodate
the range of particle sizes in which aerosols may be encountered in
air. Further, aerosols may be present in large concentrations in
the air streams in certain filtration applications. For example, in
diesel engine blow-by or other heavy duty motor exhaust or
industrial filtration applications, it is possible to encounter
aerosols in concentrations of 700 ppm to 20,000 ppm. Such
concentrations are not filtered with high efficiency using the thin
filters of the prior art; thus, multiple layers are usually
employed.
[0005] Accordingly, a substantial need exists in obtaining an
improved filtration layer having a substantial thickness, a defined
basis weight, solidity and pore size useful for a variety of
filtration processes. One useful technique is to use an aqueous
slurry based material such as that disclosed in U.S. Ser. No.
11/267,958. Sugiura et al., U.S. Pat. No. 5,755,963, teach a filter
element comprising microfibers made from a slurry to obtain a
density gradient structure useful in oil filtration. Nielsen et
al., U.S. Pat. No. 5,167,765, teach the use of polyester
bicomponent fiber and other fibers in making bonded fibrous wet
laid sheets for filtration applications.
[0006] Filter media have been configured in a variety of filter
units for many different filtration applications. In one
application, it has been common to remove liquid aerosol
particulate from a mobile gaseous phase such as air by using filter
elements comprising cellulosic and cellulosic/synthetic fiber
combinations wet-laid flat media that has been corrugated and
pleated into a useful cylindrical shaped elements of different
heights and diameters. The use of formed media comprised wholly of
glass fibers and aqueous or solvent based resins for the purpose of
consolidating the fibers mass and providing strength and structural
integrity has been practiced. Limitations thereof are specific to
fiber size (approximately 0.08 to about 4 microns fiber diameter)
and to the fact that a secondary process to apply the resin is
necessary to consolidate the filter media and provide structural
integrity for the performance and survivability of the element in
such demanding applications. Further, these filter media suffer
from resin migration during the filter media life, which in turn
causes a loss of porosity. In use, this loss of porosity is
evidenced by increased pressure drop across the filter, clogging of
pores, and cracking of the filter, thus leading to early filter
failure. Further, these filter media are brittle and may shatter
under challenging conditions, leading to catastrophic failure.
Finally, the above filter making technique has a practical limit of
about 5.0 mm thickness, such that the ability to make thicker media
for use with different aerosols or adaptation for other filtration
applications is not provided. Nevertheless, the use of wet-laid
paper-like media is prevalent in the application of removing
aerosol particulates from airstreams.
[0007] Some examples of conventional commercially available
filtration media for the separation of aerosols from air are
products available from the Porous Media Company of St. Paul,
Minn.; Keltec Technolab of Twinsburg, Ohio; ProPure Filtration
Company of Tapei, Taiwan; Finite.RTM. and Balston.RTM. filters made
by the Parker Hannifin Corporation of Mayfield, Ohio; Fai Filtri
s.r.l. of Pontirolo Nuovo, Italy; Mann+Hummel Group of Ludwigsburg,
Germany; and PSI Global Ltd. Of Bowburn Durham, United Kingdom.
[0008] A substantial need exists to provide a filter medium having
improved efficiency of removal of the liquid aerosol from the air
stream and reduced pressure drop, and acceptable basis weight and
void volume which leads to an increased useful lifetime in
application conditions. A substantial need exists to simplify the
construction of such filtration apparatus, thereby decreasing the
complication and expense of the manufacturing processes over those
currently used. A substantial need also exists to provide a filter
media having reduced brittleness that can withstand challenging
conditions without shattering. A substantial need also exists to
provide a filter medium that does not undergo resin migration
during use. A substantial need exists to provide a method of making
filter media that is adaptable for other filtration applications,
such as the removal of solid particulates from air or the removal
of impurities from water. A substantial need also exists for a
method of making a filter that is adaptable for entraining
materials such as particles and polymers that in turn provide
functionality to the filter structure. Finally, there is a
substantial need to provide a method of making filter media having
multiple layers such that each layer has a different structure or
composition, e.g. by varying permeability of the layers or by
incorporating particles into a layer. These and other advantages
are found in the filtration media disclosed below.
BRIEF DISCUSSION OF THE INVENTION
[0009] We have found that a useful filter element having a
thickness of greater than 3 millimeters can be made by combining a
bicomponent fiber and a glass fiber in a filter medium or element.
A slurry of this combination of fibers can be used to form a layer.
Once heated to the correct fusion temperature and cured the layer
forms a mechanically stable medium. The medium can be used in a
filter element having unique filtration properties unlike those of
thin cellulosic or synthetic paper layers, or other mist collection
systems or other thick fibrous media.
[0010] The unique filter medium of the invention may have a
thickness of greater than 3 millimeters, which may be made in one
step, and comprises a bicomponent fiber. Such filter medium can be
manufactured using only bicomponent fiber, but can also contain
other materials. Other fibers may be used, most preferably glass
fibers. Two or more different kinds of glass fibers may be used
advantageously in a single filter medium. Thermoplastic fibers,
binder resins, natural fibers, particulate matter, or other
filtration components may be advantageous to use along with, or
instead of glass fibers depending on the application contemplated.
Desirable materials that can add functionality to the filters of
the invention include carbon particles or fibers, metal particles
or fibers, silica or other ceramic particles, ion exchange resins,
catalysts, enzymes, and zeolites. Further, chemical modification of
the surface of fibers and/or particles may be employed
advantageously, for example by reacting glass fibers with a silane
coupling agent to modify surface energy either prior to, or after,
inclusion of the glass fibers in the filters of the present
invention. Other additive compounds may add functionality, such as
antistatic or flame retardant compounds.
[0011] The invention may comprise a filter unit comprising the
bicomponent fiber medium of the invention in combination with a
perforate support that can be formed in a housing with other
conventional filtration components. The perforate support may be
made from any suitable material, such as metal or plastic,
depending on the intended application. The filter unit may also
comprise end caps, housings, or other conventional filter unit
parts.
[0012] A method of removing a particulate from a fluid medium can
use the steps of introducing the fluid medium having entrained
particulate into contact with the filter medium passing the mobile
fluid through the filter medium wherein the particulate is retained
by the filter medium leaving a purified fluid exiting the medium.
While removal of oily aerosol from a stream of air is particularly
preferred and demonstrated, the skilled artisan will understand
that the invention also contemplates filtration of particulates
from liquids such as water, soot removal from air, and a variety of
other applications generally known in the art of filtration.
[0013] A method of removing typically a liquid aerosol entrained in
an air stream is for aerosol particulate to contact the fibrous
medium, coating the fibrous interior of the medium and accumulating
on and within the fibrous interior. As the liquid accumulates
within the filter, gravity will cause the liquid to drain from the
filter medium. Such media are often used in conjunction with a
reservoir into which the liquid drains and can be removed
continually or in a batch-wise fashion.
[0014] Multiple layered filters, wherein each layer has a different
composition, thickness, or density, may be made with ease by
employing the methods of the invention. Various layers may also
contain functional materials. For example, one layer may have a
greater permeability than another, and a different layer may
contain activated charcoal. Multiple layers are achieved with ease
by virtue of the flexibility of the process for making the filters
of the present invention.
[0015] The unique media of this invention can be used in a variety
of filtration processes including, but not limited to, removal of
particulate matter from air or other gas phase materials such as
nitrogen, natural gas, oxygen, and the like; particulate removal
from a liquid phase material, such as water, hydraulic fluid,
diesel fuel, gasoline, crankcase oil, ethanol and the like; removal
of fine particulates such as smoke, exhaust particles, dust,
asbestos, silica, clay, water vapor, oil vapor, metal vapor, and
the like; removal of nonparticulate impurities such as volatile
organic compounds (VOCs) from air or water; or removal of ozone
from air.
[0016] The filter media of this invention is particularly useful in
separating an entrained liquid aerosol from a mobile air phase. The
media of the invention has excellent characteristics of removal of
oily aerosol, for example, from a fluid stream that is largely made
of air and aerosol. Thus, when a stream of air having between 2000
and 9000 ppm of oily aerosol per ppm of total fluid, more typically
about 7000 ppm of oily aerosol per ppm of total fluid, is passed
through the filter at 60 to 100 psi, less than or equal to 2 ppm of
the aerosol remains in the air stream after filtration after a
period as long as 1000 hours and after 4000 hours is able to remove
the aerosol leaving less than or equal to 3 ppm or less of the
aerosol in the mobile air phase after 4000 hours. The media of the
invention is capable of maintaining a substantially low pressure
drop over the lifetime of the media under these same conditions,
wherein the lifetime can extend as long as 8000 hours. The pressure
drop over the media during normal operating conditions as outlined
above is less than 2 psi increase over 200 hours and is less than 1
psi additionally over a subsequent period of 7000 hours.
[0017] In a preferred embodiment, the filter medium of the
invention has a permeability of about 1 to about 2 CFM, a basis
weight of about 2,500 to about 3,000 gram/meter2, a preferred
thickness of about 8 to about 20 millimeters, and in typical
filtration applications, removes the liquid aerosol from the air
stream such that little or no aerosol penetrates the medium. We
have found that less than 20 ppm, often less than 10 ppm and most
often less than 5 ppm of the liquid aerosol penetrates the medium
under typical operating conditions using the media of the
invention.
[0018] We have further found that the media of the invention has
substantially improved burst characteristics. In other words, under
the force obtained from the pressure of the air flow through the
media, that the media of the invention has the ability to withstand
substantially increased pressure force during the lifetime of the
media than prior structures. The strengths of the bicomponent/glass
fiber media is such that it can survive pressure with a burst
strength of at least 10 psi, more preferably about 25 to about 40
psi when measured according to ASTM D774 specifications.
BRIEF DISCUSSION OF THE FIGURES
[0019] FIG. 1 is a graphical representation of the data of Table 6,
showing a Di-octyl Phthalate (DOP) efficiency (at 10.5 FPM) of
experimental filter media FM-1 and FM-2, described in Example 1,
when compared with CONTROL filter media of the present
invention.
[0020] FIGS. 2 through 5 are graphical representations of the data
shown in Tables 7 and 8 of the application. Generally, Tables 7 and
8 show that when compared to filter media made by prior art
methodology employing aqueous based binder resin and glass fiber,
the filter medium FM-1 of Example 1 provides substantially improved
removal of test oil aerosol both initially and as the filter medium
ages in use, when compared to the CONTROL sample of the prior art.
Further, the filter medium of the present invention maintains a
substantially reduced pressure drop over time, produces excellent
operating conditions in terms of discharge temperature and produces
an excellent flow rate in cubic feet per minute (CFM) over the
lifetime of the filter medium.
[0021] FIG. 6 shows the tensile strength and elongation at break
for a filter of the present invention when compared to a filter of
the prior art.
[0022] FIGS. 7A through 7F are photomicrographs of a view from the
side or inside of the filter media of the present invention,
further described in the Experimental section as FM-1, FM-2, and
FM-3 in addition to similar photomicrographs of a filter of the
prior art having glass fibers and binder resin.
[0023] FIGS. 8A and 8B show a fully formed functional coalescer of
the invention.
DETAILED DISCUSSION OF THE INVENTION
[0024] The unique filter media of the invention typically is
manufactured employing a wet laid process. The process involves
adding bicomponent fiber to an aqueous media to form slurry,
forming the slurry into a layer of fiber, and curing and drying the
layer to form the filter media. Such media can be used for general
filtration purposes, but particularly is useful in separating a
liquid aerosol from an air stream. Bicomponent fiber is a known
material in which the fiber contains an amount of polymer having a
relatively high melting point and a second amount of a polymer
having a relatively low melting point. In the formation of a layer,
the fiber is heated to a temperature such that the low melting
point polymer can melt, fuse and bind the layer into a mechanically
stable, unitary mass. The relatively high melting point polymer
component can provide mechanical strength and stability to the
layer.
[0025] Glass fiber is preferably employed along with the
bicomponent fiber and may be added along with the bicomponent fiber
in the slurry. The use of glass fiber in conjunction with the
bicomponent fiber provides control over the filtration properties
for certain applications. However, glass fiber is not a requirement
for making the filters of the invention. Bicomponent fiber alone
may be formed into a filter of the invention. Additionally,
materials such as thermoplastic fibers, inorganic fibers,
particles, binder resins, or other additives may be included in the
filter making slurry to form a filter having functionality tailored
for the application contemplated. Such materials may be included in
addition to, or instead of, glass fiber.
[0026] In selecting the bicomponent fiber, various combinations of
polymers may be useful in the present invention, but it is
important that the first polymer component melt at a temperature
lower than the melting temperature of the second polymer component
and typically below 200.degree. C. Further, the bicomponent fibers
are integrally mixed and evenly dispersed with other materials in
the filter making slurry. Melting of the first polymer component of
the bicomponent fiber is necessary to allow the bicomponent fibers
to form a tacky skeletal structure, which upon cooling, binds to
other bicomponent fibers as well as other fibers or particles in
the formed filter layer.
[0027] Bicomponent fibers having a sheath-core structure are
particularly useful in making the filters of the invention. In the
sheath-core structure, the low melting point (e.g., about 80 to
200.degree. C.) thermoplastic is typically extruded around a fiber
of the higher melting (e.g., about 200 to 260.degree. C.) point
material. In use, the bicomponent fibers typically have a fiber
diameter of about 5 to 50 micrometers often about 10 to 20
micrometers and typically in a fiber form generally have a length
of 0.1 to 20 millimeters or often have a length of about 0.2 to
about 15 millimeters. Any thermoplastic that can have an
appropriate melting point can be used in the low melting component
of the bicomponent fiber while higher melting polymers can be used
in the higher melting "core" portion of the fiber.
[0028] The cross-sectional structure of such fibers can be, as
discussed above, the "sheath-core" structure, or other structures
that provide the same thermal bonding function, such as
"side-by-side" structures or lobed fibers where the fiber tips have
lower melting point polymer. The value of the bicomponent fiber is
that the relatively low-temperature melting resin can melt under
sheet, media, or filter forming conditions to act to bind the
bicomponent fiber, and other fibers present in the sheet, media, or
filter making material into a mechanically stable sheet, media, or
filter. Once melted and fused to other fibers or particles in the
filter media of the invention, the stability of the structure is
manifested in the observation that there is no migration of
materials in the filter. Such migration is typically seen in
filters made using glass fiber and binder resins.
[0029] Typically, the polymers of the bicomponent fibers are made
up of different thermoplastic materials. For example,
polyolefin/polyester (sheath/core) bicomponent fibers may be used,
such that the polyolefin, e.g. polyethylene sheath, melts at a
temperature lower than the polyester, e.g. polyethylene
terephthalate core. Typical thermoplastic polymers having useful
melting points for use either in a high or low melting portion can
include polyolefins, e.g. polyethylene, polypropylene,
polybutylene, and copolymers thereof, polytetrafluoroethylene,
polyesters, e.g. polyethylene terephthalate, polyvinyl acetate,
polyvinyl chloride acetate, polyvinyl butyral, acrylic resins, e.g.
polyacrylate, and polymethylacrylate, polymethylmethacrylate,
polyamides, namely nylon, polyvinyl chloride, polyvinylidene
chloride, polystyrene, polyvinyl alcohol, polyurethanes, cellulosic
resins, namely cellulosic nitrate, cellulosic acetate, cellulosic
acetate butyrate, ethyl cellulose, etc., copolymers of any of the
above materials, e.g. ethylene-vinyl acetate copolymers,
ethylene-acrylic acid copolymers, styrene-butadiene block
copolymers, KRATON.RTM. rubbers available from Kraton Polymers U.S.
LLC of Houston, Tex., and the like.
[0030] Particularly preferred in the present invention is a
bicomponent fiber known as Advansa 271P, a 14 micrometer diameter
fiber available from EXSA Americas, New York, N.Y. Other useful
fibers include FIT 201 (available from Fiber Innovation Technology,
Inc. of Johnson City, Tenn.), Kuraray N720 (available from the
Kuraray Co., Ltd. of Osaka, Japan) and similar commercially
available materials. All of these commercially available
bicomponent fibers can facilitate the cross-linking of a filter
construction of the current invention by melting and fusing a
sheath polymer to other fibers of the filter construction.
[0031] Selection of melting points for the portion of the
bicomponent fiber that melts and fuses to bind the layer
mechanically is important. In any filtration application, the
mobile fluid will have an operating temperature. Mobile fluids of a
high operating temperature such as lubricant oil, hydraulic fluid,
etc. must be used with a filtration medium having fibers with a
thermal characteristic such that the material does not melt at
operating temperatures. The filter medium made using glass fiber
and bicomponent fiber tends to be relatively temperature stable due
to the presence of a relatively large mass of glass and polymer.
However, relatively little experimentation is needed to determine
the temperature at which the lower temperature polymer might
initiate failure of the medium when exposed to high temperature
mobile fluids in the filtration operation. The bicomponent fiber
can then be selected in order to obtain a dimensionally and
mechanically stable filtration medium in the presence of the target
fluid temperature.
[0032] The preferred glass fiber used in media of the present
invention include glass types known to those skilled in the art by
their designations: A, C, D, E, Zero Boron E, ECR, AR, R, S, S-2,
N, and the like. Generally, the skilled artisan will recognize that
any glass that can be made into fibers either by drawing processes
used for making reinforcement fibers or by spinning processes used
for making thermal insulation fibers. Such fibers are typically
about 0.1 to 50 micrometers (.mu.m) in diameter, more typically
about 0.2 to 20 pm, and have aspect ratio of about 10 to 10,000.
These commercially available fibers can be sized with a sizing
coating or can be unsized. Such coatings cause the otherwise
ionically neutral glass fibers to form and remain in bundles. Glass
fiber in diameter less than about 1.0 micron is not sized. Large
diameter chopped glass is typically sized. The sizing composition
and cationic antistatic agent eliminates fiber agglomeration and
permits a uniform dispersion of the glass fibers upon agitation of
the dispersion in the tank.
[0033] The typical amount of glass fibers for effective dispersion
in the glass slurry is between about 5% to about 80%, more
preferably about 50 to about 80%, by weight of the solids in the
dispersion. Blends of glass fibers can substantially aid in
improving permeability of the materials. We have found that a
useful filtration medium can be made by combining bicomponent fiber
and glass fiber. Such media, depending on glass content and glass
fiber size can obtain permeability, efficiency, and filter lifetime
sufficient for a number of applications. In applications involving
removal of a liquid aerosol from a mobile air stream, a medium
comprising a bicomponent fiber in combination with a relatively
larger glass fiber with a relatively smaller glass fiber can obtain
a useful and highly active filtration media. Such media contains a
glass fiber that contains a substantial proportion of a glass fiber
having a diameter of greater than about 1 micron and a substantial
amount of a glass fiber having a fiber diameter of less than 1.0
micron.
[0034] The combination of bicomponent fiber and glass fiber can be
formed into a useful layer which can be fused by heat into a
mechanically stable useful filter medium. While no additional
binder in the form of fiber or resin is generally needed for such
structures, this invention contemplates the use of additional
binder materials when needed for a specific application. Binder
resins can comprise water-soluble, solvent borne, or latex based
materials. Binder materials may be provided in dry form, in a
solvent, or in an aqueous dispersion. Such useful polymer materials
include acrylic polymers, ethylene vinyl acetate polymers, ethylene
vinyl polyvinyl alcohol, ethylene vinyl alcohol polymers, polyvinyl
pyrrolidone polymers, and natural gums and resins useful in aqueous
solution.
[0035] Latex-based binders may also be used to bind together the
filter media of the present invention. Latex binders can be
selected from various latex adhesives known in the art. The skilled
artisan can select the particular latex adhesive depending upon the
type of fibers that are to be bound. The latex adhesive may be
applied by known techniques such as spraying or foaming. Generally,
latex adhesives having from 15 to 25% solids are used. The
dispersion can be made by dispersing the fibers and then adding the
binder material or dispersing the binder material and then adding
the fibers. The dispersion can, also, be made by combining a
dispersion of fibers with a dispersion of the binder material. The
concentration of total fibers in the dispersion can range from 0.01
to 5 or 0.005 to 2 weight percent based on the total weight of the
dispersion. The concentration of binder material in the dispersion
can range from 10 to 50 weight percent based on the total weight of
the fibers.
[0036] Alternatively, a binder resin may be delivered from a
solvent other than water. Solvent borne binders may be advantageous
where a particular resin cannot be delivered from water, but the
properties of the resin are highly desirable. Solvent delivery is
also necessary where the polymer is reactive toward water, and the
reaction should be prevented prior to contact with the filter
fibers. Non-limiting examples of suitable solvents for delivery of
binder resins include acetone, methyl ethyl ketone, methyl isobutyl
ketone, toluene, methanol, ethanol, isopropanol, methylene
chloride, dichloromethane, hexane, cyclohexane, tetrahydrofuran,
diethyl ether, mixtures thereof and mixtures with water, and the
like. Polymers that are usefully delivered from water can include,
but are not limited to, phenolic resins, polyvinyl acetate,
polyvinyl alcohol, acrylic resins, methacrylic resins,
polyurethanes, cyanoacrylates, epoxies, melamine resins, and
polycaprolactones.
[0037] Useful examples of commercially available solvent borne
binders include phenolic resins available from Dynea of Helsinki,
Finland, and Ashland, Inc. of Covington, Ky., among others;
polyvinyl acetate available from Rohm & Haas Company of
Philadelphia, Pa., H.B. Fuller Company of Vadnais Heights, Minn.,
and Air Products and Chemicals, Inc. of Allentown, Pa., among
others; polyvinyl alcohol available from Rohm & Haas, Dow
Chemical Co. of Midland, Mich., Reichhold, Inc. of Research
Triangle Park, N.C., and Hexion Specialty Chemicals of Columbus,
Ohio, among others; acrylic resins available from Rohm & Haas
Company of Philadelphia, Pa., H.B. Fuller Company of Vadnais
Heights, Minn., and Air Products and Chemicals, Inc. of Allentown,
Pa., among others; methacrylic resins available from Ciba Specialty
Chemicals (Araldite.RTM. resins) of Tarrytown, N.Y., Dow Chemical
Co. of Midland, Mich., Hexion Specialty Chemicals of Columbus,
Ohio, and Reichhold, Inc. of Research Triangle Park, N.C., among
others; polyurethanes available from Dow Chemical Co. of Midland,
Mich. and Ciba Specialty Chemicals of Tarrytown, N.Y., among
others; cyanoacrylates available from Henkel Loctite of Rocky Hill,
Conn.; epoxies available from Dow Chemical Co. of Midland, Mich.,
Hexion Specialty Chemicals of Columbus, Ohio, and Ciba Specialty
Chemicals of Tarrytown, N.Y., among others; melamine resins
available from Ciba Specialty Chemicals of Tarrytown, N.Y., Cytec
Industries, Inc. (Cymel.RTM.) of West Paterson, N.J., and Hexion
Specialty Chemicals of Columbus, Ohio, among others; and
polycaprolactones available from Solvay America Inc. (Capa.RTM.) of
Houston, Tex.
[0038] Binder resins such as those described above can be used to
help bond such media fibers into a mechanically stable filter
medium. Such thermoplastic binder resin materials can be used as a
dry powder or solvent system, but are typically aqueous dispersions
(a latex or one of a number of lattices) of vinyl thermoplastic
resins. A resinous binder component is not necessary to obtain
adequate strength for the filter construction of this invention,
but can be used to help bond thermoplastic fibers into the filter
media matrix. Resin used as binder can be in the form of water
soluble or dispersible polymer added directly to the filter-making
dispersion or in the form of thermoplastic binder fibers of the
resin material intermingled with other fibers of the filter making
slurry to be activated as a binder by heat applied after the filter
media is formed.
[0039] Media fibers may also be incorporated into the filter media
of the present invention. Media fibers are fibers that can aid in
filtration or in forming a structural media layer. Such fiber may
be made from a number of hydrophilic, hydrophobic, oleophilic, and
oleophobic materials. Media fibers may be present with or without
glass fibers in the filter media of the present invention. When
needed, these fibers cooperate with the bicomponent fiber and any
other components present in the slurry to form a mechanically
stable, but strong, permeable filtration media that can withstand
the mechanical stress of the passage of fluid materials and can
maintain the loading of particulate during use. Such fibers are
typically monocomponent fibers with a diameter that can range from
about 0.1 to about 50 micrometers and can be made from a variety of
materials including naturally occurring cotton, linen, wool,
various cellulosic and proteinaceous natural fibers, synthetic
fibers including rayon, acrylic, aramid nylon, polyolefin,
polyester fibers.
[0040] One type of media fiber is a binder fiber that cooperates
with other components to bind the materials into a sheet. Another
type a structural fiber cooperates with other components to
increase the tensile and burst strength the materials in dry and
wet conditions. Yet another type of media fiber is one that
enhances the entrapment of specific components during filtration of
the fluid stream.
[0041] Useful media fiber materials include, but are not limited
to, polyester fibers, polyamide fibers, aramid fibers,
polypropylene fibers, copolyetherester fibers, polyethylene
terephthalate fibers, polybutylene terephthalate fibers,
polypropylene fibers, polyethylene fibers, polyvinyl acetate
fibers, polyvinyl alcohol fibers (including various hydrolysis of
polyvinyl alcohol such as 88% hydrolyzed, 95% hydrolyzed, 98%
hydrolyzed and 99.5% hydrolyzed polymers), polylactic acid fibers,
polyetherketoneketone (PEKK) fibers, polyetheretherketone (PEEK)
fibers, liquid crystalline polymer (LCP) fibers, and mixtures
thereof. Polyamide fibers include, but are not limited to, nylon 6,
66, 11, 12, 612, and high temperature "nylons" (such as nylon 46).
Further, cellulosic fibers such as cotton, viscose rayon, and other
common fiber types may be used in some embodiments of the current
invention. The thermoplastic fibers are generally fine (about
0.5-20 denier diameter), short (about 0.1-5 cm long), staple
fibers, possibly containing precompounded conventional additives,
such as antioxidant, stabilizers, lubricants, tougheners, etc. In
addition, the thermoplastic fibers may be surface treated with a
dispersing aid. The preferred thermoplastic fibers are polyamide
and polyethylene terephthalate fibers, with the most preferred
being polyethylene terephthalate fibers.
[0042] Media fibers can also include inorganic fibers such as
carbon/graphite fiber, metal fiber, metal oxide fiber, ceramic
fiber, and combinations thereof.
[0043] The filter media of the present invention also contemplates
the use of functional materials for specific filtration needs.
Functional materials may be particulates of silica, clay, carbon,
powdered metals or metal oxides; glass micro-spheres, ceramics,
thermoplastic or thermoset resin particles or fibers; catalysts
such as Hopcalite type air purification catalysts, e.g.
Carulite.RTM. Catalyst available from the Carus Corporation of
Peru, Ill.; or other structures such as carbon nanotubes, zeolites,
enzymes that are free or bound to polymeric backbones, or ion
exchange resins. Any material capable of being entrained in the
filter making slurry may be used, where a specific application may
require the use of a specialized filtration component.
[0044] The filter media of the present invention also contemplates
the use of fiber treatments to modify the surface properties of the
fibers or affect the bulk properties of the filter media. Surface
properties of glass fibers, bicomponent fibers, or other materials
present in the filter media may be modified. Acidic or basic
compounds may be added to the slurry; reactive materials that
affect the hydrophobicity or hydrophilicity may be employed either
in the slurry or by a post-treatment after fusing the bicomponent
fibers; flame retardants may be entrained; surface finish chemicals
may be used; or antistatic agents may be employed. For example,
hexamethyl disilazane (HMDZ) may be sprayed onto the formed filter
or added by dipping the formed filter in a solution of HMDZ; HMDZ
can react with e.g. glass fibers to provide a surface having
trimethylsilyl functionality, thereby rendering the glass surface
hydrophobic. Other agents may be employed to affect surface energy
of the fibers in the filter media of the present invention.
[0045] The media of the invention can be made using any system that
can accumulate the fiber into a thick layer. The media of the
invention can be made into any shape that can be formed using the
fibers of the invention. Useful forms of such a layer are flat
media, cylindrical media, and the like.
[0046] The technologies used in media making are typically related
to papermaking processes adapted to thicker layers. The skilled
artisan will appreciate that papermaking processes known as wet
laid processes are particularly useful and many of the fiber
components are designed for aqueous dispersion processing. The
machines that can be used in wet laid sheet making include hand
laid sheet equipment, Fourdrinier papermaking machines, cylindrical
papermaking machines, inclined papermaking machines, combination
papermaking machines and other machines that can take a properly
mixed slurry of components, form a layer or layers of the
components of the needed thickness, and remove the fluid aqueous
components to form a wet sheet. Wet-laid manufacturing of the
media/elements of the present invention typically comprises the
following steps: [0047] 1--Weighing fibers to the specified recipe
and proportions. [0048] 2--Mixing fibers into an aqueous slurry for
a sufficient time [between 30 and 45 minutes], at a water-to-fiber
ratio of approximately 1:0.002. [0049] 3--Vacuum forming the
media/element onto a suitable perforated cylinder, perforated
sheet, cone or any suitable shape. The forming support must be
suitably open to allow water to flow across, allow the free passage
of water and the deposit of the fibers onto the perforated form
thus creating the desired element shape and thickness. The
perforated shape is completely immersed and held under vacuum from
2-35 seconds, depending on the desired thickness and basis weight.
Vacuum level can be from 10 in. Hg to 29 in. Hg, depending on the
thickness, basis weight, density and solidity desired. [0050]
4--Retracting the formed media/element from the fiber slurry and
maintaining the vacuum for another 15-30 seconds to extract as much
of the water as possible. [0051] 5--Removing the media or element
from vacuum fixture and placing it in a thru-air drying oven to
drive off remaining water. The oven temperature and residence time
in the oven is adjusted to melt the low melting component of the
bicomponent fibers and activate fiber-to-fiber adhesion. In a
preferred embodiment, the bicomponent fiber used is Advansa 271P,
and the oven temperature is adjusted to 300.degree. F. and
residence time is 25-60 minutes. [0052] 6--Cooling the
media/element at room temperature.
[0053] The skilled artisan will recognize that an advantageous
aspect of the current invention is that no further media processing
is necessary. After carrying out the foregoing manufacturing steps,
the formed filter media are ready for incorporation into a
filtration assembly. The skilled artisan will appreciate that a
finished filter assembly can comprise end caps, housings, and the
like, and that the method of assembly and the parts required for
assembly will depend on the intended end use.
[0054] Once sufficiently dried and processed to filtration media,
the sheets are typically about 5 to 50 millimeters in thickness,
have a pore size of about 0.55 to about 50 micrometers, a basis
weight of about 50.0 to about 3,000.0 grams/meter.sup.2 or about
50.0 to about 1,000.0 grams/meter.sup.2, a solidity of about 4.0 to
about 7.0%, and a permeability of about 0.5 to about 200 fpm.
[0055] In some embodiments, the filter media of the invention may
be formed as a substantially planar web or a mat. The web or mat
may further be coated with a binder by conventional means, e.g., by
a flood and extract method and passed through a drying section
which dries the mat and cures the binder, and thermally bonds the
sheet, media, or filter. The resulting web or mat may be collected
in a large roll or left substantially flat as formed
[0056] The filter media of the invention can also be formed into a
variety of geometric shapes using forms to hold the wet composition
during thermal bonding. In forming shaped media, a layer is formed
by dispersing fibers in an aqueous system, and forming the filter
on a mandrel with the aid of a vacuum. The formed structure is then
dried and bonded in an oven. By using a slurry to form the filter,
this process provides the flexibility to form several structures,
such as cylinders, tubes, cones, and ovals.
[0057] The filter media of the present invention can further be
formed as multilayer filter media having different components in
the different layers. For example, a first layer of filter media
may be formed using the above techniques and materials, and formed
into the desired shape and thickness, pore size, etc. After the
oven drying step, the filter media may be immersed in a second
slurry having a different composition to result in e.g. different
permeability from the first layer, or by imparting functionality
such as by incorporating activated charcoal. The manufacturing
process is thus repeated to provide a two-layer filter. In this
manner, multiple filter layers may be added.
[0058] Similarly, instead of immersing the filter media in a second
slurry after the first oven drying step, the second slurry may be
applied after vacuum drying but before the final oven drying step;
in this manner, multiple layers may be deposited to the filter
media, followed by a single oven drying step that is carried out
after some or all of the filter media layers have been applied.
[0059] Thus, multiple layers may incorporate differing pore sizes,
different permeability, different fiber materials to filter
different specific components, or addition of other additives such
as particulates to different layers. The skilled artisan will
appreciate the ability of a multiply layered filter media of the
present invention to filter several specific particle types or
sizes using one filter assembly, or alternatively to provide a
media that both filters particles and entraps airborne chemicals on
a molecular scale, or media that combines any number of the uses
contemplated by various embodiments of the invention into a single
assembly.
[0060] Certain preferred arrangements according to the present
invention include filter media as generally defined, in an overall
filter construction. Some preferred arrangements for such use
comprise the media arranged in a cylindrical, pleated configuration
with the pleats extending generally longitudinally, i.e. in the
same direction as a longitudinal axis of the cylindrical pattern.
For such arrangements, the media may be imbedded in end caps, as
with conventional filters. Such arrangements may include upstream
liners and downstream liners if desired, for typical conventional
purposes.
DETAILED DISCUSSION OF THE FIGURES
[0061] FIG. 1 is a graphical representation of the data derived
from a filter efficiency test, wherein latexes having varying
particle size borne in an air stream and passed through the filters
of the present invention, labeled FM-1, FM-2, and a control sample,
labeled CONTROL. FM-1 is a single layer filter employing glass
fibers, while FM-4 is a dual layer filter employing glass fibers.
CONTROL is a filter of the prior art comprising glass fibers and a
binder resin. Particles ranging in size from 0.05 micron to 0.3
micron are employed in the test, and the particles are present at
about 6,800 ppm per million parts of the fluid passed through the
media. The number of particles present on the post- filtration side
of the filters is measured, and the result is expressed in a
percent efficiency for each particle size. It may be observed that
the filters of the present invention have a superior ability to
entrap particles over the range of particle sizes used.
[0062] FIG. 2 is a graphical representation of data derived from an
air compressor test, wherein the experimental filter FM-1 and
CONTROL were incorporated into filter elements and mounted inside
an air compressor apparatus for 8000 hours of actual run time
wherein the filters were filtering oily particulate from the air
stream during operation of the compressor. Periodic measurements
show the superior performance of the filter media of the present
invention in trapping oily aerosols in a long-term air filtration
application. Oily aerosol particulate carryover into the filtered
air was measured at both 60 psig and 100 psig. FIG. 2 shows that
the oil carryover passing through the FM-1 filter is 2.0 ppm or
less (flowing form outside to inside) for the duration of the test,
while the CONTROL filter media had about 2.0 ppm carryover
initially but became less effective over time, such that carryover
was 5.0 ppm or more by the end of the test.
[0063] FIG. 3 is a graphical representation of data derived from
the same air compressor test, showing that the pressure drop across
the medium of the invention is acceptable even in view of the
increased oil collection capacity of the medium. In the course of
the same test as conducted above, resulting in the data represented
by FIG. 1, pressure drop across the filter was also monitored. The
results show that the FM-1 filter media maintained acceptable
pressure drop over the course of the 8000 hour test, despite
entrapping more oily aerosol than CONTROL (as shown in FIG. 2). The
pressure drop for the FM-1 filter media stayed well below the
industrially acceptable maximum level of 10.0 psid for the duration
of the test, even though it entraps more oily aerosol than CONTROL,
as is shown in FIG. 2.
[0064] FIG. 4 is a graphical representation of data derived from
the same air compressor test, showing the discharge temperature of
the air stream passed through FM-1 over a test period of about 14
months (about 10,000 hours). The discharge temperature is
indicative of operating conditions and compressed air temperature.
Discharge temperatures of up to 120.degree. C. are considered the
industrially acceptable limit, as temperatures above this typically
exceed operating temperatures in machinery where the filters of the
invention may be used. The discharge temperature was acceptable
over time of the test, and in fact declined over the course of the
first ten months (about 7200 hours), showing that FM-1 was not
severely challenged or in danger of failure, even though it entraps
a higher volume of oily aerosol particles than CONTROL, as is shown
in FIG. 1.
[0065] FIG. 5 is a graphical representation of data derived from
the same air compressor test, showing the flow rate, or volume, of
air passing through the FM-1 filter medium compared to the CONTROL
medium. The air flow of the medium of the invention remained
substantially consistent over the lifetime of the test, thus
showing that in long-term use a filter of the present invention
does not become clogged, even though the FM-1 filter medium traps a
higher volume of oily aerosol than CONTROL, as is shown in FIG.
2.
[0066] FIG. 6 is a graphical representation of the stress-strain
properties of FM-1 and CONTROL. Both media were measured at a
strain rate of 2.54 cm/min, and the resulting force measured. It
can be observed that the filters of the present invention have a
higher elongation at break, and a higher tensile strength, than the
filters of the prior art.
[0067] FIGS. 7A through 7F are electron photomicrographs showing
side views of the FM-1, FM-2 media and inside and side views of the
FM-3 filter media of the invention, as well as a side view of the
CONTROL sample. The photomicrographs clearly show the glass fiber
and the bicomponent fiber in a combination matrix having a
substantial void volume, effective pore size and uniform
distribution of materials leading to a high quality, high strength
filter medium that will display high efficiency, high burst
strength, useful solidity, long lifetime, low pressure drop and
other beneficial characteristics derived from the unique structure
of the medium.
[0068] FIG. 7A shows a side view of the CONTROL filter medium at
500.times.magnification. The filter medium 10 has glass fibers 11.
FIGS. 7B and 7C show a side view of a filter medium of the present
invention, FM-1, at 200.times. (FIG. 7B) and 1000.times. (FIG. 7C),
respectively. The filter medium 20 has glass fibers 21 and
bicomponent fibers 22. FIG. 7D is a side view of a filter medium of
the present invention, FM-2, at 500.times.. Filter medium 30 has
glass fibers 31 and bicomponent fibers 32. FIG. 7E is a view of the
interior of a filter medium of the present invention, FM-3, at
50.times.. Filter medium 40 has larger carbon particles 41a,
smaller carbon particles 41b, and bicomponent fibers 42. FIG. 7F is
a side view of FM-3 at 1000.times.. This view of medium 40 shows
the smaller carbon particles 41b and bicomponent fibers 42.
[0069] FIGS. 8A and 8B are photographs of filter elements of the
present invention which are coalescers made as described in Example
8. FIG. 8A shows a coalescer formed from a filter medium of the
present invention, FM-1. FIG. 8a shows coalescer 50, having FM-1
filter medium 51 and endcaps 52. FIG. 8B shows the same coalescer
50, FM-1 medium 51, and endcaps 52. In this view one endcap 52 has
been removed to show the internal structure of coalescer 50. Filter
medium 51 has substantial thickness 53 and cylindrical apertured
support 54, upon which FM-1 filter medium 51 was formed. Also
visible is coalescing medium 55 and gap 56 present between support
54 and coalescing medium 55.
[0070] The above specification, examples and data provide a
complete description of the manufacture and use of the composition
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. As used
in this specification and the appended claims, the singular forms
"a", "an" and "the" include single and plural referents unless
clearly dictated otherwise by specific specification or claim
language. Thus, for example, reference to a composition containing
"a compound" includes a mixture of two or more compounds.
[0071] Herein when reference is made to efficiency, unless
otherwise specified, reference is meant to efficiency when measured
according to ASTM-1215-89, with 0.78.mu. monodisperse polystyrene
spherical particles, at 20 fpm (6.1 meters/min) as described
herein. However, efficiency may be specified to mean efficiency as
measured by the DOP efficiency test which is described in detail
below.
EXPERIMENTAL SECTION
General Experimental Techniques
[0072] 1. Permeability:
[0073] As discussed in the examples set forth below, permeability
relates to the quantity of air (ft.sup.3-min.sup.-, or CFM) that
will flow through a filter medium at a pressure drop of 0.5 inches
of water. In general, permeability as the term is used is assessed
by the Frazier Permeability Test according to ASTM D737 using a
Frazier Permeability Tester available from Frazier Precision
Instrument Co. Inc., Gaithersburg, Md. or a TexTest 3300 or TexTest
3310 available from Advanced Testing Instruments Corp (ATI), 243
East Black Stock Rd. Suite 2, Spartanburg, S.C. 29301,
(864)989-0566, www. aticorporation.com. [0074] 2. Pore Size:
[0075] Pore size means mean flow pore diameter determined using a
capillary flow porometer instrument such as a Model APP 1200 AEXSC
sold by Porus Materials, Inc., Cornell University Research Park,
Bldg. 4.83 Brown Road, Ithaca, N.Y. 14850-1298, 1-800-825-5764,
www.pmiapp.com. A sample of filter media is cut to 2.24 cm outer
diameter and mounted on a specimen holder. The specimen holder is
open at the top and the filter is mounted in the bottom of a well
that is 1.90 cm deep. On the underside of the specimen is a chamber
open to a path to a manometer, an air bleed needle, and a
compressed air source. The air bleed valve is opened and the
compressed air turned on to a level whereby the manometer reads
7.6.+-.1.3 cm. The well is filled with reagent grade isopropanol,
and the air bleed valve is slowly closed until a bubble appears in
the well containing isopropanol. The manometer reading is recorded
at the first bubble sighting and the pressure recorded is used to
calculate pore size. This measurement is repeated for five
repetitions. [0076] 3. Filtration Efficiency (DOP) Test:
[0077] A 6-inch wide strip of filter media is mounted in the chuck
of a TSI 8160 Automated Filter Tester, available from TSI
Incorporated of Shoreview, Minn. Dried air is fed with latex
particles and this mixture of air and particles is applied at a
pressure of 70 psi across the filter media. The face velocity of
the air stream is set by adjusting the flow rate of the
air/particle mixture as well as the opening size of the chuck. For
example, a flow rate of 32 fpm through a chuck size of 100 cm.sup.2
will result in a face velocity against the filter sample in the
chuck of 5.334 cm/sec (or 10.5 fpm). In this manner, face
velocities ranging from 0.35 fpm to 82 fpm may be achieved.
[0078] Particle sizes used in the test were 0.03, 0.05, 0.07, 0.09
0.1, 0.2, 0.3, and 0.4 microns in diameter. The concentration of
particles in the stream was about 6800 parts per million parts of
air flow across the media. The concentration of each particle size
in the effluent air is measured, so that the percent of each
particle size trapped by the filter at the designated flow rate can
be measured. The overall efficiency is the total percent of
particles trapped by the filter apparatus. Each particle size is
measured, so efficiency as a function of particle size can also be
determined.
EXAMPLE 1
[0079] A filter medium of the invention, FM-1, was made using the
following technique. Into 250 gallons of untreated tap water was
mixed Advansa 271P bicomponent fiber (obtained from EXSA Americas,
New York, N.Y.), Evanite #610 glass fiber, and Evanite #608 glass
fiber (both obtained from the Evanite Fiber Corporation of
Corvallis, Oreg.) such that the relative weight of the components
are as shown in Table 1. Mixing was carried out with a 2HP rotating
paddle mixer for between 30 and 45 minutes to obtain an aqueous
slurry of fibers. The slurry was then vacuum formed onto a
5.25''.times.9'' perforated metal cylinder by completely immersing
the cylinder in the slurry and holding it under a vacuum of
approximately 20 inches Hg for 3-10 seconds.
[0080] The formed media was then retracted from the slurry and
vacuum was maintained for 15-30 s. The media was removed from the
vacuum fixture and placed in a vented oven. The oven temperature
was set to 300.degree. C. Residence time in the oven was
approximately 35 minutes. The filter media was cooled to room
temperature at ambient conditions.
TABLE-US-00001 TABLE 1 Components of FM-1 Component Wt. (gm)
DuPont-271 (14.mu.) 1200 Evanite .RTM. glass fiber #610 (2.8.mu.)
500 Evanite .RTM. glass fiber #608 (0.8.mu.) 200
[0081] After removing from the oven and cooling, FM-1 was 2.29 cm
thick. The basis weight of FM-1 was measured as 2645
grams/meter.sup.2 (g/M.sup.2). The initial permeability of FM-1 was
found to be 1.3 ft/min.
EXAMPLE 2
[0082] A filter medium of the present invention, hereafter referred
to as FM-2, was made using the filter making process of Example 1.
The components of the filter slurry are shown in Table 2.
TABLE-US-00002 TABLE 2 Components of FM-2 Fibers Wt. (g) DuPont 271
fiber (14.mu.) 980 Evanite .RTM. glass fiber #610 (2.8.mu.) 200
Evanite .RTM. glass fiber #608 (0.8.mu.) 420
After the oven drying step, FM-2 was 0.84 cm thick. FM-2 was found
to have a basis weight of 1187 g/M.sup.2. The initial air
permeability of FM-2 was determined to be 1.4 feet/minute
(fpm).
EXAMPLE 3
[0083] A filter medium of the present invention, hereafter referred
to as FM-3, was made using the filter making process of Example 1.
The components of the filter were bicomponent fibers and carbon
particles, added to the slurry at a ratio of approximately 1:1 by
weight. The bicomponent fibers were DuPont-271 fibers. The carbon
particles were Calgon MD5695, 50-200 mesh activated carbon
particles from a coconut powder source, obtained from the Calgon
Carbon Company of Pittsburgh, Pa. The particles were mixed directly
into the slurry with no prior treatment or washing. After the oven
drying step, the filter was analyzed for weight percent of the
components. The components of the filter are shown in Table 3.
Micrographs of the inside and side views of FM-3 are shown in FIGS.
7e and 7f.
TABLE-US-00003 TABLE 3 Components of FM-3 Component Wt. %
DuPont-271 (14.mu.) 49.95 MD5695, 50-200 mesh carbon particles
50.05
[0084] The available surface area of the MD5695 particles and the
FM-3 filter media containing 50% MD5695 particles were measured
using Brunauer-Emmett-Teller (BET) nitrogen adsorption isotherm
(BET; see S. Brunauer, P. H. Emmett and E. Teller, J. Am. Chem.
Soc., 1938, 60, 309.) Samples were placed in a sampling tube and
out-gassed overnight under vacuum at 60.degree. C. The sample was
run under standard continuous flow conditions using a Micromeritics
ASAP 2010 instrument (available from Micromeritics Corporation of
Norcross, Ga.). The following measurements were made: [0085] BET
Surface Area: This is the amount of surface area on the molecular
level and is measured between relative pressure values of 0.05 and
0.3. It incorporates the concept of multi-molecular layer
adsorption. [0086] t-plot Micropore Area: A method to normalize an
isotherm and calculate the micropore area with an extrapolation of
the linear portion of the adsorption axis. [0087] Total Pore
Volume: This is the total pore volume per weight of sample. This is
the maximum volume of nitrogen penetrating at the highest pressure
applied. [0088] Average Pore Diameter: Model to aid in determining
the pore diameter from the wall area and volume. The model assumes
that the pores are right cylinders.
[0089] The available surface area of the carbon particles alone
were compared to the surface area of the particles entrained in
FM-3. The results of BET testing are shown in Table 4. The results
show that the particles entrained in the filter of the invention
did not show a significant decrease in available surface area when
incorporated in the filter using the wet-laid technique described
above.
TABLE-US-00004 TABLE 4 BET results for MD5695 particles and MD5695
particles entrained in FM-3. Total Average Pore Pore BET Surface
Micropore Volume Diameter Sample ID Area (m.sup.2/g) Area
(m.sup.2/g) (cm.sup.3/g) ({acute over (.ANG.)}) MD5695 (Carbon)
1876 668 0.942 20.1 FM-3 (values are per 1765 587 0.885 20.5 gram
of Carbon) Percent Variation from -6% -12% -6% NA MD5695 Base
Carbon
EXAMPLE 4
[0090] A filter medium of the present invention, hereafter referred
to as FM-4, was made using the filter making process above. The
components of the filter were DuPont-271 bicomponent fibers and
"media type #3" carbon fibers obtained from CarboPur Technologies,
Inc. of Montreal, Quebec, Canada. The carbon fibers are
approximately 12-14 micrometers in diameter. These two components
were added to the slurry at a ratio of approximately 1:1 by weight.
The carbon fibers were mixed directly into the slurry with no prior
treatment or washing. After the oven drying step, the filter was
analyzed for weight percent of the components and the filter was
found to comprise 1:1 bicomponent fibers to carbon fibers by
weight.
EXAMPLE 5
[0091] A filter medium of the present invention, hereafter referred
to as FM-5, was made using the filter making process of Example 1
above except that the filter was made in two steps using two
slurries of differing composition. The first slurry was formed into
a layer as described above. This sample also employed Lauscha EC-6,
a 6 .mu.m glass fiber, available from the Lauscha Fiber
International Corp. of Summerville S.C. The weight of the
components of slurry 1 is shown in Table 5 below.
[0092] A second layer was added to the first by interrupting the
first filter making procedure at the point where the layer would
otherwise go into the oven. At this point the support with the
first layer was immersed in the second slurry, slurry 2, and the
filter making process repeated; the layers were placed in the
vented oven as described in Example 1 above. Slurry 2 also differed
from the first in that 83 gallons of tap water were used instead of
250 gallons as described in Example 1. The weight of the components
of slurry 2 is shown in Table 5.
[0093] After the oven drying step, the basis weight of FM-5 was
measured to be 1489 g/M.sup.2. The Frazier permeability of FM-5 was
found to be between 1.35 and 1.5 CFM at 0.5 inches.
TABLE-US-00005 TABLE 5 Components of FM-5 slurries Wt. (gm) Slurry
1 Component DuPont-271 (14.mu.) 980 EC-6 Lauscha glass fiber (6
.mu.m) 420 Slurry 2 Component DuPont-271 (12.mu.) 330 Evanite .RTM.
glass fiber #610 (2.8.mu.) 66 Evanite .RTM. glass fiber #608
(0.8.mu.) 140
EXAMPLE 6
[0094] A filter medium of the present invention, hereinafter
referred to as FM-6, was made using the same procedure as used in
Example 5 to make FM-5, except that two oven drying steps were
employed. The first oven drying step was carried out after the
first layer of fibers from slurry 1 was applied; the second oven
drying step was carried out after the second layer of fibers from
slurry 2 was applied. The composition of Layer 1 of FM-6 was
determined to be 70% DuPont-271 fibers and 30% Evanite.RTM. #610
glass fibers. The composition of Layer 2 of FM-6 was determined to
be 71.4 DuPont-271 fibers and 28.6% 3 denier crimped polyester
fibers, obtained from Wellman, Inc. of Fort Mill, S.C.
EXAMPLE 7
[0095] DOP efficiency testing was carried out on filter media of
the invention and compared to a control filter media sample. The
control sample, hereinafter referred to as CONTROL, was a wet laid
filter medium using conventional technology to provide a filter
media of glass fibers and an aqueous binder material. CONTROL media
was obtained from the Donaldson Company of Minneapolis, Minn. under
the part number P046257. CONTROL is 1.17 cm thick, has a basis
weight of 1526 g/M.sup.2, and permeability of 1.5 ft/min.
[0096] DOP efficiency was measured at 10.5 fpm flow rate for FM-2,
FM-5, and CONTROL. The results are shown in Table 6.
TABLE-US-00006 TABLE 6 Results of initial DOP efficiency testing
for filter media FM-2, FM-4, and CONTROL. Particle Size EFFICIENCY,
% (.mu.m FM-2 FM-5 CONTROL 0.03 99.9999959 99.999929 99.9997 0.05
99.9999984 99.999946 99.9939 0.07 99.9999976 99.999939 99.9913 0.09
99.9999965 99.9999 99.987 0.10 99.99999966 99.999969 99.979 0.20
99.9999989 99.99987 99.97 0.30 99.999986 99.99926 99.98 0.40
99.999973 99.9989 99.9916
EXAMPLE 8
[0097] FM-1 was incorporated into a functioning oil coalescer for
long term testing in an oil coalescing application. A standard
polyurethane potting compound, such as any such compounds commonly
used in the filtration industry, for example materials sold under
the trade name Sentrol.RTM. (available from the General Electric
Company of Schenectady, N.Y.) or urethane potting products sold by
the Epoxies, Etc. of Cranston, R.I. or PottingSolutions Company of
Aurora, Colo., was applied into an open (top) end cap part. A
coalescing media, such as media sold under the trade name
PERFORMAX.RTM. (available from the NATCO Group, Inc. of Houston,
Tex.) or the trade name Q-PAC.RTM. (available from Lantec Products,
Inc. of Agoura Hills, Calif.) that has been encapsulated in between
two expanded metal screens was inserted into the end cap. The
vacuum formed filter media FM-1 was inserted into the end cap,
assuring a gap of approximately 1/4 inch exists between the
coalescing media and the vacuum formed filter media.
[0098] The potting compound was activated by heating in an oven
according to manufacturers specifications, to secure the two
concentric media packs. After activation, the partially formed
functioning coalescers were allowed to cool to ambient
temperature.
[0099] Polyurethane potting compound was then applied to the closed
(bottom) end cap, and the partially formed functioning coalescers
were inserted into the closed end cap, such that the concentric
media packs were positioned to maintain the 1/4 inch gap. The newly
applied potting compound was activated by heating in an oven
according to manufacturers specifications, to secure the fully
formed functioning coalescers. After activation, the functioning
coalescers were allowed to cool to ambient temperature. FIG. 8
shows a fully formed functioning coalescer made using FM-1.
[0100] In the same manner, CONTROL was formed into a functioning
coalescer prior to further testing.
EXAMPLE 9
[0101] The functioning coalescers made from vacuum formed media
FM-1 and CONTROL samples, as described in Example 7, were subjected
to long-term testing by mounting the coalescers into a Sullair
LS-10 industrial air compressor (available from the Sullair Company
of Michigan City, Ind.) and running the compressor at discharge
pressures of 60 psi and 100 psi over an 8000 hour period. Discharge
temperature was measured periodically over the duration of the
test. Additionally, during the test each sample was periodically
removed from the compressor and tested for oil carryover, pressure
drop across the filter, corrected air flow as determined by
discharge pressure of the effluent air, and DOP efficiency. The
results from the 8000 hour test are shown for FM-1 in Table 7, and
for CONTROL in Table 8. The results of oil carryover, pressure
drop, and corrected flow for FM-1 and CONTROL, as well as discharge
temperature for FM-1, are graphically represented in FIGS. 2-5,
respectively.
[0102] The results show that FM-1 had superior properties of oil
retention, as oil carryover was significantly less than for
CONTROL; that FM-1 had similar pressure drop to CONTROL, even
though it entrapped more oil than did CONTROL; and the corrected
flow was essentially unchanged for FM-1 throughout the 8000 hour
test; and that FM-1 had acceptable discharge temperature over the
duration of the test.
TABLE-US-00007 TABLE 7 Test results for long-term oil compressor
use of FM-1. Oil Pressure Applied Corrected Discharge Time,
Carryover, Drop, Pressure, Flow, Temp., hr ppm psid psi CFM
.degree. C. 320 0.7 1.8 100 128.2 88 512 1.0 1.8 100 131.6 88 691
1.2 2.1 100 129.9 93 853 1.2 2.1 100 131.5 88 990 1.3 2.2 100 131.2
89 1163 1.5 2.2 100 130.7 89 1366 1.6 2.4 100 130.3 88 1554 1.8 2.3
100 137.5 88 1754 1.7 2.4 100 136.0 89 1918 1.6 2.5 100 139.5 82
2112 1.6 2.4 100 134.1 89 2322 1.5 2.4 100 137.0 88 2542 1.6 2.5
100 139.0 85 2729 1.4 2.7 100 137.0 85 2900 1.4 2.7 100 137.0 82
3069 1.3 2.6 100 137.0 82 3144 1.5 2.7 100 137.0 82 3262 2.1 2.7
100 135.0 85 3449 1.7 2.7 100 136.0 85 3589 1.7 2.6 100 136.0 87
3757 1.7 2.6 100 136.0 88 3920 1.6 2.7 100 137.0 85 4110 1.6 2.6
100 134.0 87 4373 1.2 3.2 60 133.0 86 4553 1.2 3.2 60 131.0 82 4764
1.2 3.2 60 131.0 83 4954 1.1 3.0 60 131.0 84 5210 1.4 2.9 60 128.1
82 5447 1.0 3.3 60 129.0 82 5945 1.0 3.0 60 125.0 82 6203 1.7 2.6
100 136.0 96 6367 1.5 2.7 100 131.0 99 6552 1.4 2.7 100 132.0 94
6724 1.6 2.7 100 130.0 100 6900 2.5 2.5 100 131.0 101 6977 1.4 2.5
100 132.0 99 7169 1.7 2.5 100 132.0 97 7310 1.9 2.7 100 129.0 100
7422 1.7 2.8 100 135.0 91 7591 1.6 2.7 100 131.0 100 7732 3.0 2.9
100 132.0 100 7894 1.8 2.8 100 133.0 98 8049 1.8 2.8 100 134.0
98
TABLE-US-00008 TABLE 8 Test results for long-term oil compressor
use of CONTROL. Oil Pressure Applied Corrected Discharge Time,
Carryover, Drop, Pressure, Flow, Temp., hr ppm psid psi CFM
.degree. C. 123 0.9 1.3 100 133.5 92 406 0.6 1.7 100 136.4 93 555
1.8 1.6 100 134.6 91 716 2.0 1.8 100 136.4 93 1325 1.8 1.5 100
136.9 93 1660 1.7 1.6 101 139.4 86 2327 1.7 102 139.6 93 2931 1.6
102 140.1 84 3098 1.6 103 140.9 84 332 2.4 2.0 100 130.6 90 451 2.1
1.7 100 135.7 90 613 2.1 1.7 100 135.9 89 920 2.3 1.8 100 136.9 91
1110 3.0 2.4 60 144.2 85 1477 2.5 2.4 60 148.9 81 1804 3.2 2.6 60
147.1 84 1994 3.0 2.6 60 152.5 88 5336 5.4 2.0 100 136.5 82 5454
6.9 2.0 100 135.4 88 5621 5.2 2.0 100 133.3 99 5717 6.5 2.0 100
133.3 94 5911 4.4 2.0 100 135.0 90 6064 6.3 2.1 100 134.6 91 6131
6.7 2.2 100 135.0 97 6270 6.6 2.3 100 137.2 88 6431 6.6 2.0 100
137.2 88 6579 6.3 2.1 100 136.1 93 6886 5.9 2.2 100 137.0 89 7170
5.6 2.2 100 138.4 91 7289 5.1 2.2 100 138.2 88 7646 3.8 2.4 100
136.3 85 8024 4.9 2.3 100 134.6 96
EXAMPLE 10
[0103] Mechanical properties were measured for FM-1 and CONTROL
using 1.27 cm thick samples of each filter medium. Burst strength
was measured for FM-1 and CONTROL using a TMI Monitor Burst 200
Mullen Burst Tester (available from the Standex Engraving Group of
Chicopee, Mass.), in compliance with TAPPI T403 and ASTM D774
specifications. The burst strength of CONTROL was measured to be
14-20 psi. The burst strength of FM-1 was measured to be 37-49
psid.
[0104] Stress-strain properties of the filter media of the present
invention were measured using a Sintech Model M3000W tester,
available from the MTS Systems Corporation of Eden Prairie, Minn.
Stress-strain properties were measured using a 200 lb load cell and
a strain rate of 1 inch/min until break. Samples were cut using a
dog-bone shape die with neck proportion of 1.5 inches.times.0.5
inches. All samples were tested in the axial direction,
cross-machine direction, and 45 degrees from machine direction.
Unless noted, no differences were observed among the samples cut in
different directions.
[0105] The elongation at break was 0.44% for CONTROL, while the
elongation at break for FM-1 was 10.97%. The tensile strength was
determined to be 94.3 psi for CONTROL and 130.5 psi for FM-1. The
results of the tensile test are shown in FIG. 6. It can be observed
that FM-1 has a greater elongation at break as well as superior
tensile strength when compared to CONTROL. This result shows the
effect on physical properties of using bicomponent fibers instead
of the traditional binder resins of the prior art to bind glass
fibers in the filter medium.
[0106] While the invention has been described in connection with
specific embodiments thereof, it will be understood that it is
capable of further modifications and this application is intended
to cover any variations, uses, or adaptations of the invention
following, in general, the principles of the invention and
including such departures from the present disclosure as come with
known or customary practice within the art to which the invention
pertains and as may be applied to the essential features
hereinbefore set forth and as follows in scope of the appended
claims.
* * * * *
References