DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims are rejected as follows:
Claims 1–4, 7–10 and 12–13 are rejected under 35 U.S.C. 103 as being obvious over Viskari et al., US 2020/0061504 A1 (“Viskari”) in view of Stoyell et al., US 2004/0162203 A1 (“Stoyell”).
Regarding claim 1:
Viskari discloses a depth filter (Viskari’s pre-filter substrate, which acts as a depth filter; Viskari Abstract) comprising:
two or more layers (Viskari discloses its pre-filter substrate could have two or more layers; Viskari [0058] and [0060]), in series, wherein the two or more layers are arranged such that a pore size of each layer is reduced along a depth of the depth filter (Viskari discloses its pre-filter substrate could comprising a porosity gradient, i.e., the pores in the filter substrate reduce in size while approaching the wire-side of the substrate, Viskari [0057]; para. 0058 discloses the first layer that entails synthetic fibers, binder resin and micro-glass),
wherein at least one layer that is formed from a homogeneous aqueous suspension (Viskari discloses that various components forming the pre-filter substrate forms a fiber suspension or finish, which is mixed to a homogeneous mixture, Viskari [0057]) comprises polyaramid fiber (Viskari discloses its pre-filter substrate could comprise synthetic fibers such as aramid, Viskari [0048]), synthetic filter aid (Viskari discloses silica or glass [0040]), and polymeric binder (Viskari discloses as first binder, which could be PET/co-PET, Viskari [0048]).
Viskari does not disclose that the polyaramid fiber having a particle density of at least 1.2 grams per cubic centimeter.
In the analogous art of filters comprising polyaramid fibers, Stoyell discloses Kevlar as a suitable candidate for filter medium comprising aromatic polyamide fibers (which is polyaramid), Stoyell [0149]. Stoyell discloses its filter has good strength and resistance to handling, Stoyell [0011]. It would therefore have been obvious for one ordinary skill in the art at the time of filing for Viskari’s polyaramid to be made of Kevlar because Kevlar is known in the filtration art as a preferred candidate filter medium comprising polyaramid, and Stoyell discloses its filter has good strength and resistance to handling. Kevlar is known to have a particle density1 of 1.44 g/cm3, which falls within the claimed range.
Additionally, the instant disclosure does not teach the claimed particle density range is critical to the operation of the claimed invention. Therefore, absent evidence of criticality, this difference fails to patentably distinguish over prior art because it produces a difference in degree rather than in kind. MPEP 2044.05 (III)(A).
Regarding claim 2:
Modified Viskari discloses that the depth filter of claim 1, the at least one layer comprising:
fiber matrix comprising the polyaramid fiber, the polyaramid fiber comprising entangled polyaramid fibers (Viskari discloses its pre-filter substrates forms a fibrous nonwoven web, which reads on the fiber matrix, and Viskari discloses its fibrous nonwoven web having two different layers entangled to one another, which reads on “entangled polyaramid fibers” because Viskari discloses pre-filter could be made of synthetic fibers such as aramid, Viskari [0058] and [0068]),
the synthetic filter aid comprising synthetic filter aid particles distributed throughout the fiber matrix, (Viskari discloses inorganic fibers of silica, which is the claimed synthetic filter aid particles, are mixed with other components forming the pre-filter substrate to a homogeneous mixture, and then the mixture is laid on a wire to form the fibrous nonwoven web, which means they are distributed through the fiber matrix; Viskari [0057]) and
the polymeric binder that bonds together the entangled polyaramid fibers and the synthetic filter aid particles (Viskari discloses its binder is used for bonding various fibers to one another; Viskari [0025]).
Regarding claim 3:
Modified Viskari discloses that the depth filter of claim 1, further comprising:
from 20 to 99.5 weight percent of the polyaramid fiber (Viskari discloses 10-45 wt% of synthetic fibers, Viskari [0058]. Viskari’s range overlaps with the claimed range and support a prima facie case of obviousness. “In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990) (The prior art taught carbon monoxide concentrations of "about 1-5%" while the claim was limited to "more than 5%." The court held that "about 1-5%" allowed for concentrations slightly above 5% thus the ranges overlapped.); MPEP 2144.05(I).
from 0.5 to 80 weight percent of the synthetic filter aid (Viskari discloses 15–20 wt% of micro-glass, glass is disclosed in the instant spec. as a synthetic filter aid, Viskari therefore discloses a range falls within the claimed range; Viskari [0058]) and
from 0.5 to 5 weight percent of the polymeric binder, based on total weight fiber and filter aid (Viskari disclsoes a first binder of 0-5 wt%, overlapping the claimed range and support a prima facie case of obviousness. MPEP 2144.05(I); Viskari [0058]).
Regarding claim 4:
Modified Viskari discloses that the depth filter of claim 1, wherein the polyaramid fiber comprises polyaramid fibers (Viskari [0048]). Modified Viskari also disclose that at least a portion of the polyaramid fibers are fibrillated (Kevlar is fibrillated, Stoyell [0149]).
Regarding claim 7:
Modified Viskari discloses that the depth filter of claim 1, wherein the polymeric binder comprises polymer selected from: a urea polymer, a melamine-formaldehyde polymer, polyaminopolyamide-epichlorohydrin polymer, glyoxalated polyacrylamide polymer, or a combination thereof (Viskari discloses its polymer binder could be urea phenol, which is a urea polymer, Viskari [0027]).
Regarding claim 8:
Modified Viskari discloses that the depth filter of claim 1, wherein the two or more layers include three stacked layers (Viskari discloses its pre-filter substrate could be formed into a fibrous nonwoven web having three layers entangled to one another, Viskari [0060]):
a first layer comprising the polyaramid fiber and the thermoset polymeric binder (Viskari discloses its three layers could have its two outermost layers formed of a finish comprises at least of a first binder and synthetic fiber, and the center layer comprising at least of a first binder, micro-glass fibers and synthetic fibers, Viskari [0060] and Viskari discloses its synthetic fiber could be aramid, which is polyaramid fiber, Viskari, [0045]; One of Viskari’s outermost layer would be the claimed “first layer” and Viskari’s first binder, which could be a thermosetting polymer resin would be the claimed “thermoset polymetric binder”, Viskari [0027]),
a second layer comprising the polyaramid fiber, the thermoset polymeric binder, and the synthetic filter aid (Viskari’s center layer would be the claimed “second layer”, the first binder would be claimed “thermoset polymeric binder”, Viskari also discloses its second layer preferably comprises 10-20 wt% bi-or multicomponent fibers, which is the claimed synthetic filter aid, Viskari [0060], [0045], [0027] and [0061]),
a third layer comprising the polyaramid fiber, the thermoset polymeric binder, and the synthetic filter aid (the other of Viskari’s outer layer would be the claimed “third layer”, and the first binder would be the claimed “thermoset polymeric binder”, Viskari discloses its third layer preferably comprising 5-15 wt-% bi-or multicomponent fibers, which is the claimed “synthetic filter aid,” Viskari [0060] and [0061]),
wherein: the second layer is located between the first layer and the third layer (Viskari [0060]–[0061])
the second layer contains an amount of the synthetic filter aid (Viskari discloses its second layer comprising 10–20 wt-% bi-or multicomponent fibers, which is the claimed “synthetic filter aid,” Viskari [0060] and [0061]),
the third layer contains an amount of the synthetic filter aid (Viskari discloses its third layer preferably comprising 5-15 wt-% bi-or multicomponent fibers, which is the claimed “synthetic filter aid,” Viskari [0060] and [0061]), and the amount of the synthetic filter aid in the third layer is greater than the amount of the synthetic filter aid in the second layer (take an example, where Viskari’s second layer comprising 10 wt% bi-or multicomponent fibers, and Viskari’s third layer comprising 15 wt-% bi-or multicomponent fibers, such example would read on the limitation that “the amount of the synthetic filter aid in the third layer is greater than the amount of the synthetic filter aid in the second layer” with both ranges consistent with the disclosed range, Viskari [0061]).
Regarding claim 9:
Modified Viskari discloses that the depth filter of claim 8, further comprising a fourth layer (Viskari’s fine-filter substrate, Viskari [0068]), wherein the fourth layer comprises synthetic non-woven material (Viskari discloses its fine-filter substrate could be made similar to the above discussed pre-filter substrate, Viskari discloses its pre-filter substrate is could form synthetic nonwoven, and therefore, Viskari’s fine-filter substrate comprises synthetic non-woven material the same as that disclosed in Viskari’s pre-fitler, Viskari [0057] and [0067]).
Regarding claim 10:
Modified Viskari discloses that the depth filter of claim 9, wherein the synthetic non-woven material comprises polyaramid, coated polyaramid, polyester, or coated polyester (Viskari discloses aramid, which is polyaramid, Viskari [0068]).
Regarding claim 12:
Modified Viskari discloses that a method of removing particles of different sizes from a fluid, the method comprising passing the fluid through the depth filter of claim 1 (modified Viskari discloses its depth filter has pores of variable filter size, wherein the pore size gets the smaller the deeper in the filter, and Viskari discloses its filter removes solid particles from gases utilization depth filtration, Viskari [0001] and [0005]).
Regarding claim 13:
Modified Viskari discloses that the method of claim 12, wherein the fluid contains particles having a size range from 0.2 microns to 25 microns (Viskari discloses a mean flow pore size for pre-filter substrate between 8 to 10 microns, falling within the claimed range. Viskari [0080].)
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Viskari in view of Stoyell as applied to claim 1 above, and further in view of Swaminathan et al., US 2016/0361674 A1 (“Swaminathan”).
Regarding claim 5:
Viskari does not disclose that the depth filter of claim 1, wherein the synthetic filter aid comprises a metal silicate, activated carbon, or a combination thereof. Viskari discloses its synthetic filter aid could be “carbon.” Viskari [0040] and [0048].
However, in the analogous art of filter medium comprising polyaramid fibers, Swaminathan discloses its filter media could include other components to achieve desired properties. Swaminathan discloses an example of including activated carbon. Swaminathan [0122]. It would therefore have been obvious for one ordinary skill in the art at the time of filing for modified Viskari’s depth filter to include activated carbon as disclosed by Swaminathan to achieve desired properties such as a high particulate efficiency and/or fluid separation efficiency as disclosed by Swaminathan, Swaminathan Abstract.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Viskari in view of Stoyell as applied to claim 1 above, and further in view of Segit et al., CN 103476477 A (“Segit”)2.
Regarding claim 6:
Modified Viskari does not disclose that the depth filter of claim 1, wherein the synthetic filter aid comprises calcium silicate.
However, Viskari discloses its filter could comprise inorganic fibers like glass (Viskari [0040]).
In the analogous art of liquid filter media comprising aramid fibers, Segit discloses its liquid filter medium may include glass fibers, such as CR glass fiber, which comprises calcium silicate, Segit [0013]). Segit discloses CR glass fiber could be included in liquid fiber filter to provide relatively high surface area. Segit [0013]. It would therefore have been obvious for one ordinary skill in the art at the time of filing for Viskari’s glass fiber to be CR glass fiber that comprises calcium silicate because to provide relatively high surface area.
Claims 11 and 14 are rejected under 35 U.S.C. 103 as being unpatentable over Viskari in view of Stoyell as applied to claim 1 above, and further in view of Woo et al., US 2016/0114272 A1 (“Woo”).
Regarding claim 11:
Modified Viskari does not disclose that the depth filter of claim 1, further comprising the two or more layers in series assembled at an interior of a filter housing, wherein the two or more layers and the filter housing are sterilized by exposure to gamma radiation.
Similar to modified Viskari, Woo discloses a multi-layer depth filter. Woo Fig. 1, [0088]. Similar to modified Viskari, Woo discloses its filter is configured for liquid. Woo [0008]. Additionally, Woo discloses a filter housing (Woo’s filter cell). Woo [0095]. And Woo discloses its depth filter is subjected to radiation treatment such as gamma irradiation to reduced bioburden. Woo [0010]. It would therefore have been obvious for one ordinary skill in the art at the time of filing for Viskari’s filter to include a filter housing and for Viskari’s filter media and added filter housing to be subjected to the gamma irradiation for the purpose of reducing bioburden. A person of ordinary skill in the art would be motivated to include a filter housing such that the irradiation is enclosed inside the housing to prevent unnecessary radiation exposure.
Regarding claim 14:
Modified Viskari does not disclose that the method of claim 12, further comprising passing the fluid through the depth filter to remove cellular debris from the fluid.
Similar to modified Viskari, Woo discloses a multi-layer depth filter. Woo Fig. 1, [0088]. Similar to modified Viskari, Woo discloses its filter is configured for liquid. Woo [0008]. Additionally, Woo disclose its fluid comprises cellular debris. Woo [0024]. It would therefore have been obvious for one ordinary skill in the art at the time of filing for Viskari’s depth filter to be used for fluid comprising cellular debris because such fluid is known in the depth filtration art as being suitable to be filtered by depth filters.
Response to Arguments
Claim Rejections - 35 USC § 112(b)
The examiner drops the current rejection because the applicant has amended the claims to overcome the current rejection.
Claim Rejections - 35 USC §§ 102 and 103
The applicant amends the claims to include a limitation of polyaramid fiber having a particle density of at least 1.2 grams per cubic centimeter and argues that Viskari does not each such requirement, Applicant Rem. dated Jan. 14, 2026 (hereinafter “Applicant Rem.”) ps. 5–6. The applicant requests withdrawal of the rejections. Id. at p. 6.
In view of the newly included limitation of particle density, the examiner withdraws the current 35 U.S.C, §102(a)(1) rejection. However, a new ground of rejection over Viskari in view of Stoyell is provided. Details are provided above.
Applicant’s arguments regarding dependent claims mainly relies on the patentability of claim 1, and since claim 1 is not allowable, the request for allowing dependent claims are not granted.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to QIANPING HE whose telephone number is (571)272-8385. The examiner can normally be reached on 7:30-5:00 M-F.
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/Qianping He/Examiner, Art Unit 1776
1 See NPL document: Kevlar Aramid Fiber Technical Guide, Dupont 2017, Table II-1, p. 5.
2 A copy of Segit’s original document and machine translation are provided in the office action. The examiner relies on the original document for the figure and machine translation for the text.