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 .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 2 March 2026 has been entered.
Amendments
Applicant’s amendments to claim 1 have been entered and considered for this action.
Claim Interpretation
The term “box dryer” in claim 1 is interpreted to encompass apparatuses that comprise an enclosed static drying chamber. Such apparatuses may alternatively be referred to in the art as a drying oven, a drying cabinet, or a drying box.
Claim Rejections - 35 USC § 103
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1 and 2 are rejected under 35 U.S.C. 103 as being unpatentable over De et al. (J. Mater. Chem., 2000, 10, 2289-2293) in view of Tanaka et al. (JP H0840727 A), Han et al. (CN 107298446 A), Rahman et al. (Ceramics International, 2008, 34(8), 2059-2066), and Lucas (WO 2019068596 A1). The previously provided English machine translations of Han (CN 107298446 A) and Tanaka (JP H0840727 A) are referenced in the analysis below.
Regarding claim 1, De teaches a method for producing a monodisperse, amorphous and spherical SiO2 powder (obtaining monodisperse dense spherical silica powders; p. 2290, col. 1, ¶ 1), the method comprising the steps of: adding CH3COOH to H2O and stirring ; after the stirring, adding TEOS and stirring (TEOS was added to a mixture of acetic acid and water under stirring; Section 2.1; adding under stirring implies that stirring was started before the addition); removing the synthetic stock solution by filtration and washing the silica particles (“the powder could be separated by filtration”; Section 2.1; “after washing twice”, Section 3.1); and, after the washing, drying the silica particles to obtain dried silica particle powder (dried spherical silica powders (obtained after the end of the reaction after washing twice); Section 3.1). De further teaches that the size of the silica particles is 2-3 μm (these units grew to 2000-3000 nm dense spherical silica at the end of the reaction); Section 4), which falls in the instantly claimed range.
De does not teach removing the synthetic stock solution in a filter press or washing the solids with water, and is silent on the moisture content of the dried powder, other than to note about 5% weight loss by heating up to about 500 °C due to elimination of absorbed water and water formed due to condensation of silanols (Section 3.1). De also does not teach drying in a box dryer at 90 °C for 24 hours, and instead indicates drying at 150 °C for 16 hours (Section 3.1).
However, Tanaka teaches a method of generating similar silica microspheres by a sol-gel method (alkoxysilane is continuously hydrolyzed and condensed in an aqueous solution… to form a silica sol suspension, which is then subjected to solid-liquid separation; [008]) and further teaches that the spherical silica particles of 0.2 to 5 μm can be isolated by removing the stock solution in a filter press (the average particle size [is] 200 to 5,000 nm…The silica particle slurry thus obtained is separated by a conventional solid-liquid separation operation, and suitable solid-liquid separators include … a filter press; [0011]).
Furthermore, Han also discloses a method to form silica microspheres of similar size (0.3 μm to 40 μm; [0010]) from a sol-gel synthesis comprising adding TEOS to an aqueous acid solution and isolating the silica powder precipitate ([0067]-[0070]). Han further teaches that the silica powder (white precipitate) is washed repeatedly with water ([0070]).
Lucas also discloses similarly sized silica microspheres (1 μm to 15 μm) and further describes them as being anhydrous and having a suitable water content of 0.5 wt% or less (page 7, paragraph 3). Lucas further discloses that silica particles with these properties have surprisingly good cleaning properties compared with other silicas (page 4, paragraph 4) and that removing water produces a dense particle (page 4, paragraph 2).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the method of De to use a filter press, as taught by Tanaka, and to wash with water, as taught by Han, and to dry to less than 0.5 wt% water or less, as taught by Lucas.
One of ordinary skill would have been motivated to use a filter press because while De teaches a filtration, they are silent on the details and Tanka teaches that a filter press is an appropriate choice for isolating a similar product from a similar synthesis. One of ordinary skill in the art would have been additionally motivated to wash the silica microspheres with water because Han teaches that such a washing is appropriate for a related synthesis of very similar products, and because one of ordinary skill would understand that the extra washing is a way to afford a more pure product. They would have been further motivated to dry the product of modified De to a moisture content of 0.5% or less, as taught by Lucas, because Lucas teaches that doing so affords dense particles that have surprisingly good cleaning properties in cosmetic compositions.
Regarding the drying conditions, while De indicates drying at 150 °C for 16 h, Rahman studies various drying techniques for silica particles prepared via a sol-gel synthesis, including oven drying at 80 °C for 24 h (dried in conventional drying oven at 80 °C for 24 h; Section 2.1.1) and that oven drying achieves low levels of moisture (Table 2). Furthermore, it is noted that there is a well-known relationship between drying temperature and time: that drying at lower temperature requires longer times to achieve the same moisture levels.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a box dryer (drying oven), as taught by Rahman, to dry the particles in the method of modified De. One of ordinary skill in the art would have been motivated to do so because while De is silent on the drying apparatus, Rahman teaches that such an apparatus is successful at achieving low levels of moisture for silica particles prepared by sol-gel synthesis. One of ordinary skill in the art would have found it further obvious to choose a temperature in the range of 80 °C- 150 °C, because Rahman teaches that the low end of the range is successful at drying silica particles using longer times, while De teaches that the high end can be used with shorter times. It would have been further obvious to vary the time of drying along with the temperature by routine experimentation. One of ordinary skill in the art would have been motivated to do so in order to achieve the desired moisture level of less than 0.5 wt% that is taught by Lucas.
Furthermore, generally, differences temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such a temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." See MPEP 2144.05 and In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). In the instant case, Applicant has shown no evidence that the drying temperature of 90 °C is critical.
Regarding the whiteness of the particles being at least 90 and the purity at least 99.9%, modified De teaches a process that is substantially identical to that instantly claimed, and so it is expected that the method taught by the prior art will afford particles with the same whiteness characteristics and purity as those instantly disclosed.
Once a reference teaching product appearing to be substantially identical is made the basis of a rejection, and the examiner presents evidence or reasoning to show inherency, the burden of production shifts to the applicant. "[T]he PTO can require an applicant to prove that the prior art products do not necessarily or inherently possess the characteristics of [their] claimed product. Whether the rejection is based on inherency’ under 35 U.S.C. 102, on prima facie obviousness’ under 35 U.S.C. 103, jointly or alternatively, the burden of proof is the same, and its fairness is evidenced by the PTO’s inability to manufacture products or to obtain and compare prior art products." In re Best, 562 F.2d 1252, 1255, 195 USPQ 4380, 483-34 (CCPA 1977)), see MPEP 2112. Applicant has not clearly shown an unobvious difference between the instant invention and the prior art’s product.
Alternatively, one of ordinary skill would have found it obvious to modify by routine optimization the method of modified De, for example by adding extra washing steps, in order to achieve the claimed properties. One of ordinary skill in the art would have been motivated to do so because highly pure silica microspheres have various applications in the clinical, biomedical, and electronic packaging fields, as taught by De (Section 1).
Regarding claim 2, modified De teaches the method of claim 1, where De further teaches the TEOS:CH3COOH:H2O reacted at a molar ratio of 1:4:4 (Section 2.1).
Response to Arguments
Applicant’s arguments, see pages 6-13 of the reply filed 2 March 2026, with respect to the rejections of claims 1 and 2 under 35 USC § 103 have been fully considered and are persuasive with respect to the fact that the previously applied prior art does not utilize the specific drying conditions recited in amended claim 1. Therefore, the prior rejections have been withdrawn. However, upon further consideration, a new ground(s) of rejection is made over De et al. (J. Mater. Chem., 2000, 10, 2289-2293) in view of Tanaka et al. (JP H0840727 A), Han et al. (CN 107298446 A), Rahman et al. (Ceramics International, 2008, 34(8), 2059-2066), and Lucas (WO 2019068596 A1), as analyzed above.
Applicant further asserts, pages 6-7, that the proposed combination lacks a proper motivation to combine. This argument is not persuasive.
Applicant is correct that De investigates the mechanism of particle formation, but De still teaches all of the claimed features recited in the above rejection, and clearly envisions applications in clinical, biomedical, and electronic packaging fields (Introduction). Additionally, there is no requirement in the instant claims to perform the reaction at an “industrial scale,” and the motivations to achieve specific purity levels and moisture levels are applicable at all scales.
Furthermore, Tanaka merely provides the teaching that a filter press is an appropriate device with which to filter silica powders of the same sizes as those obtained by De. No evidence has been provided that differences noted between the method of Tanaka and the method of De are relevant to the specific removal device implemented.
Applicant further argues, pages 7-8, that the proposed combination would result in technical barriers that would have discouraged a person of ordinary skill from pursuing it. This argument is also not persuasive.
Han is used to introduce a water washing step where De indicates only ethanol and acetone washes. Again, while the method of De and of Han are not identical, it is noted that washing with water is very common in the art, and one of ordinary skill in the art would recognize that both the methods of Han and of De would generate by-products that are soluble in water, and therefore a water wash would be appropriate to both methods. Furthermore, there is no technical barrier to applying a water washing step to a method that utilizes water as a solvent and already incorporates ethanol washes.
Likewise, the argument that using a filter press, a water wash, and a drying step to achieve a specific moisture content requires substantial re-engineering is not supported. These are each basic process steps in preparative chemistry that can be simply combined with a high expectation of success.
Applicant further argues, pages 8-11, that the claimed method achieves unpredictable results. The data presented do not support this conclusion.
Regarding drying, it cannot be said that it is unexpected that a longer drying step affords lower moisture content. Additionally, there are no data presented that show Applicant’s specific choice of drying at 90 °C in a box dryer for 24 hours provide any significant difference from drying at higher temperature for shorter times or using a different drying apparatus. Applicant’s comparison to unmodified De is not convincing because it does not take into the contributions of Tanaka, Han, and Lucas, or the additional teachings of Rahman.
Regarding the filtration and washing steps, it is also not surprising that an additional washing step affords a product with higher purity. Applicant has not provided any evidence that the specific choice of a filter press, as opposed to an alternate filtration apparatus, is critical to generating particles with the recited properties.
Furthermore, arguments presented by the applicant cannot take the place of evidence in the record. In re Schulze, 346 F.2d 600, 602, 145 USPQ 716, 718 (CCPA 1965) and In re De Blauwe, 736 F.2d 699, 705, 222 USPQ 191, 196 (Fed. Cir. 1984). Examples of statements which are not evidence and which must be supported by an appropriate affidavit or declaration include statements regarding unexpected results, commercial success, solution of a long-felt need, inoperability of the prior art, invention before the date of the reference, and allegations that the author(s) of the prior art derived the disclosed subject matter from the inventor or at least one joint inventor. MPEP 716.01(c)(II).
Applicant further argues, pages 11-13, against the Examiner’s use of inherency and optimization. These arguments are also not persuasive.
First, the rejections presented previously and above do not state that the process of De alone would inherently have the recited properties, but rather that when De is combined with the modifications taught by Tanaka, Han, and Lucas, the recited properties would follow. No data or argument rebutting this assertion of inherency has been presented.
Secondly, Applicant’s arguments regarding routine optimization again focus only on the contribution of De. As noted above, washing with water is a routine step in preparative chemistry that is also specifically taught by Han and drying to levels of moisture below 0.5 wt% is taught by Lucas. Therefore drying and washing to afford higher purity would be obvious to one of ordinary skill in the art and the extent of washing and drying would be subject to routine optimization.
Applicant’s assertion that these steps would only be implemented by recognition of the relationship between drying conditions and whiteness are therefore unpersuasive. It is also again noted that Applicant provides no data in the specification or otherwise that the specific drying parameters are critical to the whiteness level achieved.
Applicant further argues, pages 13-14, against the Examiner’s citation to Ex parte Obiaya in the response to arguments included with the last Office action. These arguments are also not persuasive.
In particular, Applicant’s rebuttal compared the method of Lucas alone to the instant invention. But Examiner did not assert that it was Lucas’s method that would yield particles with the advantages of the instant invention. Rather, it is the method suggested by the combination of De, Tanaka, Han, and Lucas, taken together, that would suggest a process that generates particles with the properties necessary to have the advantages recognized by applicant. One cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Nicholas A Piro whose telephone number is (571)272-6344. The examiner can normally be reached Mon-Fri, 8:00 am-5:00 pm.
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/NICHOLAS A. PIRO/Assistant Examiner, Art Unit 1738
/PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735