Federal Circuit disposition — 25-1653

N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
IN RE: KWANGJIN SONG,
Appellant
______________________
2025-1653
______________________
Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. 15/707,151.
______________________
Decided: February 18, 2026
______________________
K WANGJIN SONG, Rockwell, NC, pro se.
MARY L. K ELLY , Office of the Solicitor, United States
Patent and Trademark Office, Alexandria, VA, for appellee
John A. Squires. Also represented by K AKOLI CAPRIHAN,
N ICHOLAS T HEODORE MATICH , IV, ROBERT J. MCMANUS .
______________________
Before D YK, HUGHES , and STOLL , Circuit Judges.
P ER CURIAM .
Kwangjin Song appeals pro se from a decision of the
Patent Trial and Appeal Board (“Board”) affirming an ex-
aminer’s final rejection of several claims of U.S. Patent Ap-
plication No. 15/707,151 (“patent application”) as
anticipated or obvious over prior art. We affirm.
Case: 25-1653 Document: 41 Page: 1 Filed: 02/18/2026

-- 1 of 10 --

IN RE: SONG 2
BACKGROUND
Appellant Song is one of three listed inventors of the
patent application, filed on September 18, 2017, which ap-
pellant prosecuted pro se. The application is directed to an
“oriented multilayer porous film,” which is used as a sepa-
rator dividing the positive and negative electrodes of cer-
tain battery types. J.A. 1249.1 Independent claim 48
recites:
A multilayer porous film comprising at least one
oriented layer, the at least one oriented layer com-
prising:
a) a matrix polymer selected from the
group of a first polymer having a crystal-
line melting temperature (“Tm”) or a glass
transition temperature (“Tg”) of 180°C, or
higher, a second polymer other than the
first polymer, and combinations thereof;
b) a plurality of interconnecting pores
yielding a Gurley air permeability of 1
sec/100 cc or greater and a porosity of 90%
or less; and
c) an ionic conductivity characterized by a
MacMullin number of 1 to 15.
J.A. 1063.
The examiner rejected claims 48, 49, 55, and 57 under
35 U.S.C. § 102(a)(1) as anticipated by U.S. Patent Publi-
cation No. 2012/0145468 to Pekala et al. (published
June 14, 2012) (“Pekala”). Pekala is directed to a “mi-
croporous polymer film . . . constructed for use in an energy
storage device.” J.A. 1174. The examiner rejected
1 Citations to “J.A.” refer to the corrected joint ap-
pendix filed by the parties. Dkt. No. 24.
Case: 25-1653 Document: 41 Page: 2 Filed: 02/18/2026

-- 2 of 10 --

IN RE: SONG 3
claims 60, 62, 69–73, 75–79, 83–86, 107, and 112 under
35 U.S.C. § 103 as obvious over Pekala. Appellant ap-
pealed to the Board, and the Board affirmed.
Appellant timely appeals to our court. We have juris-
diction under 28 U.S.C. § 1295(a)(4)(A).
D ISCUSSION
“To anticipate a claim, a prior art reference must dis-
close every limitation of the claimed invention, either ex-
pressly or inherently.” Rapoport v. Dement, 254 F.3d 1053,
1057 (Fed. Cir. 2001). A prior art reference need not use
the same language as the invention to be anticipating.
Adasa Inc. v. Avery Dennison Corp., 55 F.4th 900, 913
(Fed. Cir. 2022). Rather, the question is whether the ref-
erence enables a person of ordinary skill in the art
(“POSA”) to practice an embodiment of the invention as
claimed without undue experimentation. Am. Calcar, Inc.
v. Am. Honda Motor Co., 651 F.3d 1318, 1341 (Fed. Cir.
2011). A claim is unpatentable as obvious “if the differ-
ences between the claimed invention and the prior art are
such that the claimed invention as a whole would have
been obvious” to a person of ordinary skill in the art
(“POSA”) at the effective filing date. 35 U.S.C. § 103. A
single prior-art reference may render a claim obvious if a
POSA would have been motivated to modify the prior art
to arrive at what is claimed. Arendi S.A.R.L. v. Apple Inc.,
832 F.3d 1355, 1361 (Fed. Cir. 2016).
I
Appellant’s arguments are primarily directed to the re-
jection of independent claim 48 as anticipated. Pekala dis-
closes a “microporous polymer film . . . constructed for use
in an energy storage device” having “three-dimensional in-
terconnecting and interpenetrating pore and polymer net-
works” and comprising a “polymer matrix” including
ultrahigh molecular weight polyolefin (“UHMWPE”).
J.A. 1192 ¶¶ 15–17.
Case: 25-1653 Document: 41 Page: 3 Filed: 02/18/2026

-- 3 of 10 --

IN RE: SONG 4
First, appellant argues that claim 48 is not anticipated
because Pekala does not disclose an “oriented layer.” As
the Board recognized, the examiner considered that the ap-
plication specification defines “oriented” as “an alignment
of polymer chains within the film in a specific direction.”
J.A. 4 (citing J.A. 1076, 1256 ¶ 51). Claim 48 does not re-
cite, and the specification does not suggest, a quantitative
orientation threshold for “oriented.” The Board concluded
that because Pekala teaches biaxial stretching, “some ori-
entation of the polymer chains within the film must occur.”
J.A. 4–5. The examiner found that Pekala inherently dis-
closes the claimed “oriented layer” because Pekala teaches
a biaxial stretching method that appellant’s application
discloses would cause a film to become oriented. Appellant
disagrees, arguing that the composition and procedures
disclosed in Pekala would either fail to produce orientation
or would undo any existing orientation. The Board con-
cluded that Pekala teaches biaxially stretching a film,
which would inherently orient the polymer chains in a
manner similar to appellant’s film.
The Board’s determination that Pekala’s film discloses
an oriented layer is supported by substantial evidence. Ap-
pellant discloses that “orientation can be obtained by
stretching or compressing a precursor film.” J.A. 1256
¶ 51. The examiner found, and the Board agreed, that Pek-
ala teaches a stretching step. J.A. 1076 (citing J.A. 1195
¶ 56); J.A. 1079 (citing J.A. 1196 ¶ 68); see J.A. 4–5. Nota-
bly, Pekala describes a film embodiment that is “biaxially
oriented.” J.A. 1195 ¶ 56. The examiner further noted that
another reference disclosed molecular orientation that re-
sulted from the same UHMWPE composition and stretch
ratios. J.A. 1079. This is substantial evidence that sup-
ports the Board’s determination that Pekala discloses a
film that is inherently “oriented” as broadly defined in the
application.
Second, appellant contends that claim 48 is not antici-
pated because Pekala does not disclose “a plurality of
Case: 25-1653 Document: 41 Page: 4 Filed: 02/18/2026

-- 4 of 10 --

IN RE: SONG 5
interconnecting pores yielding a Gurley air permeability of
1 sec/100 cc or greater and a porosity of 90% or less.”
J.A. 1063. The examiner reasonably found that Pekala dis-
closes interconnecting pores yielding permeability, poros-
ity, and ionic conductivity properties within the ranges
recited in claim 48. J.A. 1076-77 (citing J.A. 1196, 1199)
(identifying example films disclosed in Pekala with perme-
ability measured by Gurley numbers greater than 1, poros-
ity of 90% or less, and ionic conductivity measured by
MacMullin numbers between 1 and 15). Appellant’s con-
tention that Pekala teaches a two-layer film formed by
overlaying rather than by the coextrusion, lamination, or
coating methods disclosed in the specification is also un-
persuasive because the scope of claim 48 is defined by its
structure, not by any particular manufacturing process.
See AFG Indus., Inc. v. Cardinal IG Co., 375 F.3d 1367,
1372–73 (Fed. Cir. 2004) (holding that the term “layer” in
a structural claim is not limited to any particular method
of manufacture).
Third, appellant argues that claim 48 is not antici-
pated because Pekala does not disclose other beneficial
properties of the inventive film. These properties are not
recited in claim 48. For example, appellant argues that
Pekala fails to disclose the claimed pore structure because
Pekala’s annealing would result in irregular or closed
pores, making it difficult to measure average pore size. But
claim 48 recites no pore-size limitation. Consequently, ap-
pellant’s attempts to distinguish Pekala as being “ex-
tremely annealed” and lacking “substantial uniformity” in
pore size are unavailing because they have no bearing on
any limitations in claim 48. Appellant’s Br. 38. Appellant
also argues that Pekala’s film contains inorganic fillers,
lacks a shutdown temperature (“Tsd”), and lacks a melt-
down temperature (“Tmd”). But the claim does not recite
limitations related to these properties, so any differences
in those properties do not exclude Pekala.
Case: 25-1653 Document: 41 Page: 5 Filed: 02/18/2026

-- 5 of 10 --

IN RE: SONG 6
Appellant also contends that some of the beneficial
properties not recited in the claim are nevertheless inher-
ent in a film produced in accordance with the disclosed pro-
cess and should be treated as claim limitations. But
unrecited inherent properties are not claim limitations.
Finally, appellant argues that the claimed invention
here is “broader” than the prior art. Appellant’s Br. 16.
But appellant misapprehends the significance of a broader
claim scope. A claim is anticipated if it reads on even a
single embodiment in the prior art. Atlas Powder Co.
v. Ireco, Inc., 190 F.3d 1342, 1346 (Fed. Cir. 1999). This is
so “regardless of whether it also covers subject matter not
in the prior art.” Id. In other words, an inventor cannot
overcome an anticipation rejection by showing that the ap-
plied-for claim is broader than the prior art.
The Board did not err in concluding that claim 48 is
unpatentable as anticipated by Pekala.
II
Appellant also disputes the Board’s finding that de-
pendent claim 49 is anticipated by Pekala. Claim 49 re-
cites “[t]he film of claim 48, wherein the matrix polymer is
made from a method that comprises incorporating at least
one of a biobased material, a biodegradable material, or
combinations thereof.” J.A. 1063. Importantly, claim 49
does not require the matrix polymer to comprise a biobased
or biodegradable material, but only requires that the ma-
trix polymer be made from a method that incorporates such
a material. The claim therefore recites a product by pro-
cess, as recognized by the Board. The patentability of a
product-by-process claim is determined by the structure of
the resulting product, not by the performance of the process
steps. Greenliant Sys., Inc. v. Xicor LLC, 692 F.3d 1261,
1267–68 (Fed. Cir. 2012). As claim 49 adds no structural
limitations to claim 48, the Board’s conclusion that
claim 49 is anticipated by Pekala is supported by the same
reasoning as claim 48.
Case: 25-1653 Document: 41 Page: 6 Filed: 02/18/2026

-- 6 of 10 --

IN RE: SONG 7
Appellant provides no independent arguments con-
cerning the rejections of claims 55 and 57, which also de-
pend from claim 48. Since we agree that the Board’s
decision concerning claim 48 was supported by substantial
evidence, we affirm the rejections of claims 55 and 57.
III
We next turn to the claims rejected on obviousness
grounds. Appellant contests the rejection of claims 60, 62,
69–73, 75–79, 83–86, 107, and 112.2 Each of these claims
was rejected as obvious over Pekala. Claim 60 recites the
film of claim 48 wherein, in relevant part, “one or more lay-
ers of the film further comprise a porogent material of
95% wt. % to 0.001 wt. %.” J.A. 1064. The examiner found
that appellant’s application expressly disclosed that silica
acts as a porogen and that Pekala teaches a film incorpo-
rating silica as a filler material in a range overlapping the
claimed range, establishing a prima facie case of obvious-
ness. See In re Geisler, 116 F.3d 1465, 1469 (Fed. Cir.
1997).
Appellant argues that claim 60 embraces only films
made by a wet process and that Pekala’s inorganic fillers,
including silica, act as porogens only for dry-process films,
not wet-process films. But claim 60 does not recite dry- or
wet-process limitations. Even if it did, patentability would
depend only on the resulting structures. See Greenliant,
692 F.3d at 1267–68. Because appellant does not dispute
that silica acts as a porogen for dry-process films, and dry-
2 Appellant submitted amendments to claims 69 and
70 after final rejection that would have changed their de-
pendency from claim 60 to claim 48, which the examiner
declined to enter. The Board considered the claims without
appellant’s proposed after-final amendments, as do we.
See 37 C.F.R. § 1.116.
Case: 25-1653 Document: 41 Page: 7 Filed: 02/18/2026

-- 7 of 10 --

IN RE: SONG 8
process films are within the scope of claim 60, appellant’s
argument fails.
Appellant argues that Pekala does not render obvious
the pore-size limitation of claim 62. Claim 62 recites “[t]he
film of claim 60, wherein at least a portion of at least one
of the outer surfaces of the film comprises interconnecting
pores having an average pore size characterized by a size
ratio of 0.001 to 1,000 relative to the average pore size of
an inner layer of the film.” J.A. 1065. The examiner found,
and the Board agreed, that Figures 5A and 5B in Pekala
depict a wide range of pore sizes. In light of the large range
of size ratios in the claim spanning six orders of magnitude,
the Board’s conclusion that Pekala teaches a film meeting
the pore-size limitation in claim 62 was supported by sub-
stantial evidence.
With respect to claims 69 through 73, appellant con-
tends that performing the process steps in these claims in-
volves a different process than Pekala discloses and results
in structures different from those disclosed in Pekala. As
with claim 49, these are product-by-process claims for
which patentability turns on the final product. See Green-
liant, 692 F.3d at 1267–68. Claim 69 recites the film of
claim 48 wherein a film layer is “made by a dry method
comprising . . . orienting the sheet in at least one direc-
tion,” and claim 70 recites the film of claim 48 wherein a
film layer is “made by a wet method comprising . . . orient-
ing the sheeting in at least one direction, and extracting
the diluent from the oriented film.” J.A. 1065. Claims 71,
72, and 73 depend from claim 70 and recite limitations re-
lating to the diluent recited in claim 70. Appellant has the
burden of producing evidence to establish a nonobvious
structural difference between the resulting product and the
prior art. Greenliant, 692 F.3d at 1268; see In re Marosi,
710 F.2d 799, 803 (Fed. Cir. 1983). But appellant provides
no evidence that performing the process steps in claims 69
through 73 alters the structural limitations recited in
Case: 25-1653 Document: 41 Page: 8 Filed: 02/18/2026

-- 8 of 10 --

IN RE: SONG 9
independent claim 48. The Board did not err in upholding
the examiner’s rejection of claims 69 through 73.
With respect to dependent claims 75, 77–79, and
83–85, which all depend from dependent claim 60, appel-
lant argues in a single sentence that “[t]he claimed wet
UHMWPE films all neither comprise a porogen of p-SiO 2,
nor extremely annealed morphologies, nor a merely over-
lapped 2-layer structure.” Appellant’s Br. 47. Appellant
makes the same arguments for dependent claims 86, 107,
and 112. Appellant appears to argue here, as to the Board,
that Pekala’s two-layer structure is assembled by stacking
instead of coextrusion, but this is another attempt to dis-
tinguish the manufacturing process, not the claimed struc-
ture. Appellant’s other arguments, as we understand
them, were not made to the Board and are forfeited. See In
re Google Tech. Holdings LLC, 980 F.3d 858, 863 (Fed. Cir.
2020).
Appellant argues that Pekala does not satisfy the limi-
tations of claim 76. Claim 76 depends from claim 75, fur-
ther reciting that “one or more layers of the film comprise
the compatibilizer.” J.A. 1068. The Board agreed with the
examiner’s finding that Pekala discloses a coating on the
surface of the inorganic particles that promotes compatibil-
ity between the particles and electrolytes. Appellant ar-
gues that the claimed compatibilizer must enhance
“compatibility between components within an immiscible
blend.” Appellant’s Br. 47. But the specification does not
support such a narrow meaning for a compatibilizer, in-
stead disclosing that “compatibilizing polymers . . . bear
functional groups . . . to interact with other polymers, com-
ponents, surfaces, fillers, ions, solvents, and the like.”
J.A. 1268 ¶ 147. The Board’s conclusion was supported by
substantial evidence.
The Board did not err in concluding that claims 60, 62,
69–73, 75–79, 83–86, 107, and 112 are unpatentable as ob-
vious over Pekala.
Case: 25-1653 Document: 41 Page: 9 Filed: 02/18/2026

-- 9 of 10 --

IN RE: SONG 10
IV
We have considered appellant’s other arguments and
find them unpersuasive. We affirm the Board’s decision.
AFFIRMED
Case: 25-1653 Document: 41 Page: 10 Filed: 02/18/2026

-- 10 of 10 --