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 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.
Claim(s) 1-5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Citti ‘445 (US 2012/0227445 A1) in view of Saito ‘568 (US 2019/0322568 A1).
Regarding claim 1, Citti ‘445 teaches:
a forming step of causing a first molten glass to flow down along a surface of a forming trough comprising an yttrium-containing oxide by a down-draw method to form a glass ribbon (¶ [0023], [0043], [0046], [0049], [0063])
the forming trough comprises a Mg-rich layer comprising magnesium on the surface of the forming trough (¶ [0051], [0052], [0059], [0069]).
Citti ‘445 is silent regarding the first molten glass comprising TiO2. In analogous art of down-draw glass forming, Saito ‘568 suggests an aluminum, magnesium, and silicon-containing composition glass for forming by a down-draw method which contains TiO2 (¶ [0023], [0039]) as a known glass composition for down-draw forming, and for the benefit of forming a glass with properties such as devitrification resistance and meltability, cost effectiveness, high strain point, low thermal shrinkage, and high Young’s modulus (¶ [0003]). Saito ‘568 also notes that TiO2 provides advantages of reducing viscosity at high temperature and thus increasing meltability, and suppressing solarization (¶ [0039]). 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 Citti ‘445 by making the first molten glass comprise a composition comprising TiO2, as suggested by Saito ‘568, as a known glass composition for down-draw forming, and for the benefit of forming a glass with properties such as devitrification resistance and meltability, cost effectiveness, high strain point, low thermal shrinkage, and high Young’s modulus, and for the benefit of reducing viscosity at high temperature and thus increasing meltability, and suppressing solarization.
Regarding claim 2, Citti ‘445 further teaches the forming trough is an alumina-based forming trough (¶ [0022]), and the Mg-rich layer comprises spinel as a main component (¶ [0051], [0069]).
Regarding claim 3, Saito ‘568 suggests the first molten glass as described above, and further that the first molten glass comprises MgO (¶ [0023], [0029]).
Regarding claim 4, Citti ‘445 further teaches, as a preliminary step to the forming step, a formation step of causing a second molten glass comprising MgO to flow down along the surface of the forming trough to form the Mg-rich layer on the surface of the forming trough (¶ [0051]-[0052]).
Regarding claim 5, Saito ‘568 suggests the first molten glass as described above, and further suggests the first molten glass comprises as a glass composition, in terms of mass% (¶ [0023]):
50-80% SiO2 (¶ [0024])
3-25% Al2O3 (¶ [0025])
0-20% B2O3 (¶ [0027])
0-25% Li2O+Na2O+K2O (¶ [0028])
0-20% MgO (¶ [0029])
0-20% CaO (¶0030])
0-20% SrO (¶ [0032])
0-20% BaO (¶ [0033])
0-1% As2O3 (¶ [0043])
0.001-2% SnO2 (¶ [0041])
0.002-10% TiO2 (¶ [0039])
SnO2/(As2O3+SnO2) is from 0.001-1 (¶ [0041], [0043]),
wherein the claimed ranges overlap the ranges disclosed by Saito ‘568. It has been held that where the claimed ranges overlap or lie inside ranges disclosed by the prior art, a prima facie case of obviousness exists. See MPEP 2144.05.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. US 2019/0322563 A1 and US 2015/0004390 A1 discuss a spinel coating on an isopipe.
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/ERIN SNELTING/Primary Examiner, Art Unit 1741