PRECISION FABRICS GROUP, INC. v. TIETEX INTERNATIONAL, LTD.

Filing 57

MEMORANDUM OPINION AND ORDER. Signed by JUDGE THOMAS D. SCHROEDER on 1/15/2015, that PFG's motion to strike (Doc. 38 ) is DENIED, but the opinion of Dr. Wilkie will not be considered, and the disputed claim term "intumescent" from the '162 and '639 patents is construed to describe "a substance that swells and chars upon exposure to heat or flame." Associated Cases: 1:13-cv-00645-TDS-LPA, 1:14-cv-00650-TDS-LPA(Daniel, J)

IN THE UNITED STATES DISTRICT COURT
FOR THE MIDDLE DISTRICT OF NORTH CAROLINA
PRECISION FABRICS GROUP, INC.,

)
)
Plaintiff,
)
)
v.
)
)
TIETEX INTERNATIONAL, LTD.,
)
)
Defendant.
)
_________________________________)
)
PRECISION FABRICS GROUP, INC., )
)
Plaintiff,
)
)
v.
)
)
TIETEX INTERNATIONAL, LTD.,
)
)
Defendant.
)

1:13cv645

1:14cv650

MEMORANDUM OPINION AND ORDER
THOMAS D. SCHROEDER, District Judge.
These consolidated patent cases turn on the parties’ disputed
construction of the term “intumescent” appearing in the claims of
U.S. Patent Nos. 8,796,162 (’162 Patent) and 8,501,639 (’639
Patent) held by Plaintiff Precision Fabrics Group, Inc. (“PFG”). 1
PFG alleges that Defendant Tietex International, Ltd. (“Tietex”)
is infringing the patents, and Tietex has denied infringement and
asserted various counterclaims.

1

PFG also moves to strike the

Case number 1:13cv645 involves the ’639 patent; case number 1:14cv650
involves the ’162 patent.
The parties have agreed that the claim
construction for the ’639 patent will apply to the ’162 patent, given
their similarity. (Doc. 25.) All citations are to the record in case
number 1:13cv645, unless otherwise noted.

declaration

of

Tietex’s

expert

in

construction of the term at issue.

support

of

(Doc. 38.)

the

latter’s

The court held a

claim construction hearing on December 23, 2014.

For the reasons

stated herein, the court adopts the claim construction advanced by
PFG.
I.

BACKGROUND
The ’162 and ’639 patents are both for inventions relating to

lightweight fabric that is flame retardant and “intumescent.”
(Doc. 47-2 at 3 (’162 Patent) col. 1, ll. 15–23; Doc. 37-1 at 2
(’639 Patent) col. 1, ll. 17–24.)

The fabric is single-layer,

non-woven, and stitch-bonded; this “substrate” is treated with a
finish

comprising

an

“intumescent,

flame

retardant

coating.”

(’162 Patent col. 12, ll. 7–14; ’639 Patent col. 12, ll. 47-50).
Being

lightweight

and

thermally

protective,

the

invention

is

suitable for various applications, including furniture, vehicle
components, and building components.

(’162 Patent col. 1, ll. 15–

23; ’639 Patent col. 1, ll. 17–24).

As PFG presented at the

hearing, an asserted advantage of its invention is that, because
the intumescent swells and chars upon exposure to flame, it not
only retards flame but forms a protective thermal barrier over the
holes of the stitch-bonded fabric.
According to the allegations of PFG’s amended complaint,
Tietex manufactures a fabric with “a single layer of a non-woven,
stitch-bonded substrate treated with an intumescent substance,”
2

infringing both the ’162 and ’639 patents.
¶¶ 14–26.)

(Doc. 27 (Am. Compl.)

Tietex denies infringement and asserts counterclaims

for a declaration that it has not infringed either of PFG’s
patents, that both of PFG’s patents are invalid, and that neither
is enforceable; and for unfair competition and abuse of process.
Pursuant to Local Patent Rule 104.3, the parties have filed
a joint claim construction statement, agreeing on the meaning of
several terms, including the following:
•

a “flame retardant” is “[a] substance that can suppress,
reduce, or delay combustion and/or propagation of flame
when a substrate is exposed to heat or flame”; and

•

a “finish” is
substrate.”

“[a]

substance

that

is

applied

to

a

(Doc. 24 (Joint Claim Construction Statement) at 1.)
The parties ask the court to construe only the claim term
“intumescent.”

(Id. at 2–3.)

To define this term, Tietex relies

in part on the expert opinion of Dr. Charles A. Wilkie, presented
in

the

form

Statement

at

of

his

6;

Doc.

declaration.
24-2.)

PFG

(Joint
has

Claim

moved

to

declaration and to preclude Dr. Wilkie’s testimony.

Construction
strike

the

(Doc. 38.)

However, since Tietex did not present Dr. Wilkie at the claim
construction hearing, preclusion is unnecessary, leaving only the
motion to strike.
The parties have each filed a claim construction brief, and
the motion to strike Dr. Wilkie’s declaration has been fully

3

briefed.

Following the claim construction hearing on December 23,

2014, these matters are now ripe for resolution.
II.

ANALYSIS
A.

Legal Standard

Claim construction is a question of law to be determined by
the court.

Markman v. Westview Instruments, Inc., 517 U.S. 370,

389–91 (1996).

The claims of a patent are what define the

invention itself, Phillips v. AWH Corp., 415 F.3d 1303, 1312 (Fed.
Cir. 2005) (en banc), and are to be given the meaning they “would
have to a person of ordinary skill in the art in question,” id. at
1313.
A person of ordinary skill in the art “is deemed to read the
claim term not only in the context of the particular claim in which
the disputed term appears, but in the context of the entire patent,
including the specification.” Id. The patent’s own specifications
and claims are intrinsic evidence of what the patent’s terms mean.
The specification is not just “always highly relevant” to claim
construction; rather, it is usually dispositive, being “the single
best guide to the meaning of a disputed term.” Id. at 1315 (quoting
Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.
Cir. 1996)); see also 35 U.S.C. § 112(a) (“The specification shall
contain a written description of the invention, and of the manner
and process of making and using it, in such full, clear, concise,
and exact terms as to enable any person skilled in the art to which
4

it pertains, or with which it is most nearly connected, to make
and use the same, and shall set forth the best mode contemplated
by the inventor or joint inventor of carrying out the invention.”).
The patent’s specification may rely on the ordinary meaning of a
term, but it may also “reveal a special definition given to a claim
term by the patentee that differs from the meaning it would
otherwise possess.
governs.”

In such cases, the inventor’s lexicography

Phillips, 415 F.3d at 1316.

Also relevant as intrinsic

evidence is the patent’s prosecution history: the record of the
proceedings before the Patent and Trademark Office, which includes
the prior art cited during the examination of the patent.
1317.

Id. at

Although not always clear, the prosecution history can be

helpful in understanding whether the inventor has intentionally
narrowed the scope of a claim.

Id.

Courts may also consider evidence extrinsic to the patent
itself.

Although

sometimes

probative

of

a

claim’s

meaning,

extrinsic evidence is “less significant” and “less reliable” than
intrinsic evidence.

Id. (quoting C.R. Bard, Inc. v. U.S. Surgical

Corp., 388 F.3d 858, 862 (Fed. Cir. 2004)).

Several types of

evidence fall into the category of extrinsic evidence, each with
its own limitations.

Dictionaries and treatises can be helpful

aids in understanding “the way in which one of skill in the art
might use the claim terms,” id. at 1318, although no dictionary
definition can “contradict any definition found in or ascertained
5

by a reading of the patent documents,” id. at 1322–23 (quoting
Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1584 n.6 (Fed.
Cir. 1996)).
understanding

The opinions of experts can also be helpful in
how

one

with

ordinary

skill

in

the

art

would

understand a term, but they are less useful when they are just
“conclusory, unsupported” definitions, or when they contradict the
intrinsic evidence.

Id. at 1318.

Expert testimony must be viewed

with caution because it is evidence “generated at the time of and
for the purpose of litigation and thus can suffer from bias that
is not present in intrinsic evidence.”

Id.

Moreover, this bias

“can be exacerbated if the expert is not one of skill in the
relevant art or if the expert’s opinion is offered in a form that
is not subject to cross-examination.”

Id.

When a court considers all probative evidence of a claim’s
meaning, as the Federal Circuit has stated, there is “no magic
formula or catechism for conducting claim construction.”
1324.

Id. at

What counts is that the court “attach the appropriate

weight” to the evidence from the various sources, acknowledging
the value and limitations of each kind of evidence.
B.

Id. at 1324.

Expert Opinion of Charles A. Wilkie, Ph.D.

As a preliminary matter, the court must consider PFG’s motion
to strike the declaration of Tietex’s expert, Dr. Charles A.
Wilkie, based on Rule 702 of the Federal Rules of Evidence.
38.)

(Doc.

PFG argues that while Dr. Wilkie may be qualified as an
6

expert in the chemistry of flame retardants, he is not qualified
in the pertinent art to render an opinion as to the patent claims
in this case.

Tietex resists the motion on the grounds that Rule

702 allows the court to consider Dr. Wilkie’s opinion as to the
term

“intumescent”

from

a

chemical

engineer’s

perspective

irrespective of whether he is a person of skill in the pertinent
art.

(Doc. 53 at 3–4.) 2
As mentioned above, patent claims “are analyzed in great part

from the perspective of a person of ordinary skill in the art, and
testimony explaining the technical evidence from that perspective
may be of great utility to the factfinder.”

2

Sundance, 550 F.3d at

The parties have assumed, without analysis, that the Federal Rules of
Evidence apply in this context. Yet, if a court’s claim construction
ruling is purely a question of law, subject to de novo review by the
Federal Circuit, some have questioned what aid an expert would be. See
Fed. R. Evid. 702(a) (providing that an expert may testify in the form
of an opinion if, among other things, his “scientific, technical, or
other specialized knowledge will help the trier of fact to understand
the evidence or to determine a fact in issue”); Peter S. Menell et al.,
Patent Claim Construction: A Modern Synthesis and Structured Framework,
25 Berkeley Tech. L.J. 711, 815 (2010) (noting that it is an open question
whether the Federal Rules of Evidence apply to Markman hearings since
the hearings “are not heard by a jury” and suggesting that district
courts “tak[e] a liberal approach to applying” the rules of evidence to
such hearings). But see Steven M. Bauer, Richard Myrus, Jeremy P. Oczek,
First Markman, Now Festo: A Simplified Approach to Patent Litigation
Trials, 4 Sedona Conf. J. 73, 83 (2003) (arguing that Markman hearings
should be governed by the Federal Rules of Evidence). Here, the question
appears academic because, as explained infra, the expert lacks at least
ordinary skill in the pertinent art.
Phillips, 415 F.3d at 1313
(directing courts to determine a claim term’s meaning by reference to
how one of ordinary skill in the art would understand it); Sundance,
Inc. v. DeMonte Fabricating Ltd., 550 F.3d 1356, 1363 (Fed. Cir. 2008)
(noting that under Rule 702, as the Federal Circuit applies it to patent
cases, an expert is only qualified if he possesses at least ordinary
skill in the art).

7

1361.

Under Rule 702, as the Federal Circuit applies it in patent

cases, “where an issue calls for consideration of evidence from
the perspective of one of ordinary skill in the art, it is
contradictory to Rule 702 to allow a witness to testify on the
issue who is not qualified as a technical expert in that art.”
Id. at 1363.
complex.

The application of this rule in this case is not

Dr. Wilkie opined on the level of skill that a person of

ordinary skill in the pertinent art would have — and then candidly
acknowledged that he lacks this skill.
The pertinent art, as disclosed by the patents in their “Field
of the Invention” descriptions, is flame retardant fabrics. 3

In

preparing his expert opinion on the meaning of “intumescent” as
used in the claims, Dr. Wilkie discovered that he did not know the
skill level of a person of ordinary skill in the art of flame
retardant fabrics. So, he consulted with two others and gave their
opinion as his own.

(Doc. 40-3 (Wilkie Dep.) at 121:21—126:11.)

In this way, Dr. Wilkie has submitted in his declaration, as his
opinion,
that one of ordinary skill in the art would have an
undergraduate degree in a discipline such as chemistry,
chemical engineering or other related engineering
disciplines, materials science, textile engineering, or
textile or paper chemistry, or related disciplines.
Such person would most likely be employed in the textile
3

At the claim construction hearing, PFG argued that the pertinent art
was fabrics or textiles. Regardless of the proper breadth of the art,
fabrics are undoubtedly a part of it. Certainly Dr. Wilkie, who defined
the pertinent art as “[f]ire-retardant fabrics,” thought so. (Wilkie
Dep. at 123:22.)

8

industry but should also have some experience in flame
retardancy.
I feel that a minimum of two years of
experience with textiles and a minimum of two years of
flame retardancy experience would likely be required.
(Doc. 24-2 (Wilkie Decl.) ¶ 16.)
It is plain from Dr. Wilkie’s declaration that a person of
ordinary skill would have some experience working with textiles.
During his deposition, Dr. Wilkie was asked about his textile
background.

He had none.

(Wilkie Dep. at 15:7–21, 127:20–25.)

Because Dr. Wilkie does not possess at least ordinary skill in the
pertinent art, he cannot aid the court in determining how a person
of

ordinary

skill

in

the

art

would

understand

the

term

“intumescent” in the context of the claims in this case and is
therefore not qualified under Rule 702 for purposes of the present
motion.
PFG has moved to strike Dr. Wilkie’s declaration. But motions
to strike apply to pleadings.

See Fed. R. Civ. P. 12(f); 5C

Charles A. Wright et al., Federal Practice & Procedure § 1380 &
n.8.50 (3d ed. 2004 & Supp. 2014).
declaration,

which

is

not

a

Rather than strike Dr. Wilkie’s

pleading,

the

court

disregard it for claim construction purposes.

will

simply

See DiPaulo v.

Potter, 733 F. Supp. 2d 666, 670 (M.D.N.C. 2010) (disregarding,
rather than striking, a surreply brief).
C.

Construing “Intumescent”

The ‘639 patent claims provide, in relevant part, as follows:

9

What is claimed is:
1.
A fabric consisting of a single layer of a
non-woven substrate,
wherein the non-woven substrate is treated with
an intumescent finish comprising one or more
flame
retardant
phosphorous
compounds
or
nitrogen compounds, . . . .
*

*

*

11. A fabric consisting of a single layer of a
non-woven substrate,
wherein the non-woven substrate is treated with
a finish comprising an intumescent, flame
retardant coating, . . . .
12. A fabric consisting of a single layer of a
non-woven substrate,
wherein the non-woven substrate is treated with
a finish comprising an intumescent, flame
retardant coating, . . . .
*

*

*

17. An article of furniture comprising a fabric
consisting of a single layer of a non-woven
substrate,
wherein the non-woven substrate is treated with
an intumescent finish comprising one or more
flame
retardant
phosphorous
compounds
or
nitrogen compounds, . . . .
(’639 Patent col. 12, ll. 5-9, 47-50, 65-66; col. 13, ll. 1-2;
col.

14,

ll.

1-5,

Correction) at 1.)

as

amended

by

Doc.

37-1

(Certificate

of

The parties have stipulated that the ’162

patent’s language is sufficiently similar for purposes of this
motion.

(See Doc. 56 (Claim Construction Hr’g Tr., Dec. 23, 2014)

at 7:9–11.)
The parties propose very different definitions of the term

10

“intumescent.”

PFG

urges

a

simple

definition,

arguing

that

“intumescent” describes a “substance that swells and chars upon
exposure to heat or flame.”
at

3.)

PFG

derives

specifications:

(Joint Claim Construction Statement

this

definition

from

the

patents’

In the “Background of the Invention” sections,

the patents explain, “Coatings used to absorb heat have been formed
from one or more intumescent compounds.

Intumescent compounds are

compounds that react on contact to flame by charring and swelling.”
(’162 Patent col. 1, ll. 52–55; ’639 Patent col. 1, ll. 54–57).
Tietex

urges

a

more

complex

definition,

defining

“intumescent” as
a fire retardant that swells when heated to provide
thermal protection to a substrate and, when used on a
fabric, has the following four essential components: 1)
a carbonific (i.e., carbon compound that has multiple
hydroxyl groups (“—OH” groups) or other groups that will
allow reaction with an acid source[)]; 2) an acid source
that will react with the carbonific; 3) a spumific (i.e.,
a material that will generate nonflammable gases when
heated); and 4) a skin-forming resin binder that
prevents the escape of generated gases when the
intumescent composition swells.
(Joint Claim Construction Statement at 3.)
definition

in

specifications,

part

from

which

a

different

disclose

the

Tietex derives its

section

components

of
of

the

patents’

“intumescent

system[s]” and explain how the components interact to create the
charring and swelling and thus act as a thermal barrier:
The thermal barrier of the fabric is provided by an
intumescent finish that chars and swells upon contact to
flame.
11

There are four basic components to any intumescent
system: a phosphorous-releasing catalyst, a source of
carbon (i.e., a carbonific), a resinous material, and a
blowing agent that is a source of nonflammable gas. On
exposure to flame, these components interact to form the
thermal barrier. . . .
(’162 Patent col. 7, ll. 25–31; ’639 Patent col. 7, ll. 25–31).
The remainder of the above-quoted paragraph goes on to explain how
the “four basic components to any intumescent system” interact to
trigger the intumescent reaction. 4
Tietex contends that the inventors essentially acted as their
own

lexicographers,

“intumescent.”

displacing

the

ordinary

meaning

of

For an inventor to act as his own lexicographer,

the court must find that the patentee “‘clearly set forth a
definition of the disputed claim term’ other than its plain and
ordinary meaning.

It is not enough for a patentee to simply

disclose a single embodiment or use a word in the same manner in
all embodiments, the patentee must ‘clearly express an intent’ to
redefine the term.”

Thorner v. Sony Computer Entm’t Am. LLC, 669

F.3d 1362, 1365 (Fed. Cir. 2012) (quoting Helmsderfer v. Bobrick
Washroom Equip., Inc., 527 F.3d 1379, 1381 (Fed. Cir. 2008)).
PFG

argues

that

Tietex

4

inappropriately

reads

the

Tietex argues that its proposed construction of “intumescent” only
deviates from the “four basic components” in order to provide a more
easily understandable definition for the jury. Tietex agreed that it
would be amenable, alternatively, to simply limiting the definition of
“intumescent” to a verbatim repetition of the four basic components
mentioned in the specifications. (See Claim Construction Hr’g Tr. at
93:2—94:19.)

12

specification

definition

of

an

“intumescent

system”

into

the

phrases used in the claims themselves, which refer instead to
intumescent coatings and intumescent finishes — not systems.

The

potential problem caused by Tietex’s construction is not unique to
this case. The Federal Circuit has previously framed the difficult
issue

of

reading

claims

in

light

of

specifications

without

warrantlessly reading specifications into the claims:
[T]his court recognizes that it must interpret the
claims in light of the specification, yet avoid
impermissibly
importing
limitations
from
the
specification.
That balance turns on how the
specification characterizes the claimed invention. In
this respect, this court looks to whether the
specification refers to a limitation only as a part of
less than all possible embodiments or whether the
specification read as a whole suggests that the very
character of the invention requires the limitation be a
part of every embodiment.
For example, it is
impermissible to read the one and only disclosed
embodiment into a claim without other indicia that the
patentee so intended to limit the invention.
On the
other hand, where the specification makes clear at
various points that the claimed invention is narrower
than the claim language might imply, it is entirely
permissible and proper to limit the claims.
Alloc, Inc. v. Int’l Trade Comm’n, 342 F.3d 1361, 1370 (Fed. Cir.
2003)

(citations

omitted);

accord

Andersen

Corp.

v.

Fiber

Composites, LLC, 474 F.3d 1361, 1373 (Fed. Cir. 2007) (“It is true
that

we

have

warned

against

importing

limitations

from

the

specification into the claims absent a clear disclaimer of claim
scope.

We have also recognized the difficulty faced by district

courts in trying to walk that tightrope.” (citation omitted)).

13

PFG

contends,

and

the

court

finds,

that

the

claim

term

“intumescent” should be accorded its “plain and ordinary meaning”:
a substance that swells and chars upon exposure to heat or flame.
(See ’162 Patent col. 1, ll. 52–55; ’639 Patent col. 1, ll. 54–
57.)

The

specification

lists

four

basic

components

of

an

intumescent “system” and how those components interact to create
a thermal barrier by swelling and charring.
intended

to

act

as

their

own

Had the inventors

lexicographers,

the

phrase

“intumescent system” would have been included in the claims —
otherwise

there

would

have

been

no

point

in

the

inventors’

departure from ordinary meaning — but it is not. 5
The claims do in fact limit the composition of the intumescent
agent, but not to the level of specificity advanced by Tietex.
Instead,

where

the

term

“intumescent”

is

used

at

all,

the

composition is merely limited to compounds containing phosphorous
or nitrogen.

(See, e.g., ’162 Patent col. 12, ll. 11–13; ’639

Patent col. 12, ll. 8–10 (as amended), col. 12, ll. 50–65, col.
13, ll. 2–20, col. 14, ll. 4-5; accord Doc. 41-11 at 8 (“The
following is an examiner’s statement of reasons for allowance:
The primary reason for allowance is that none of the cited art

5

Tietex also argues that the court should construe the specification’s
statement that “[t]here are four basic components to any intumescent
system” to mean that “there are four basic components to every
intumescent system.” Whether or not that is a proper understanding of
the specification language, the argument is ultimately unpersuasive
given that the court finds that the specification phrase “intumescent
system” has not been used in or referred to by the patents’ claims.

14

teaches, suggests or otherwise renders obvious treating a stitch
bonded fabric comprising cellulosic and polyester fibers with an
intumescent composition comprising phosphorous or nitrogen.

It is

noted that intumescents function not just as flame retardants but
as thermal barriers.”)).

If the “four basic components” language

was intended to redefine “intumescent,” these claim limitations on
the intumescent composition would have been “mere surplusage,”
already being part of the “intumescent system.”

Tex. Instruments

Inc. v. U.S. Int’l Trade Comm’n, 988 F.2d 1165, 1171 (Fed. Cir.
1993).
This ordinary meaning of the term is also confirmed by the
extrinsic evidence presented by both PFG and Tietex. PFG has cited
numerous

definitions,

from

both

ordinary

and

technical

dictionaries, as well as technical treatises, in support of its
proposed construction.

(Doc. 36 at 7–8; Doc. 24-1 at 4 nn.1–3.)

The publications cited by Tietex, however, similarly support PFG’s
construction.

(See, e.g., Doc. 36 at 8 (“[Intumescence is] [t]he

property of a material to swell when heated . . . .” (quoting
McGraw-Hill Dictionary of Scientific and Technical Terms 1108 (6th
ed. 2003))); id. at 9 (“Intumescence can be described as a fireretardant technology which causes an otherwise flammable material
to foam, forming an insulating barrier when exposed to heat.”
(quoting G. Camino & S. Lomakin, Intumescent Materials, in Fire
Retardant Materials 318 (A.R. Horrocks and D. Price eds., 2008))).)
15

Expert

opinion

also

supports

this

construction.

PFG’s

expert, G.A.M. Butterworth, who meets and exceeds Dr. Wilkie’s
standard of ordinary skill in the art (compare Doc. 24-2 ¶ 16,
with Doc. 24-1 ¶¶ 4–10), defines “intumescent” as “a substance
that swells and chars upon exposure to heat or flame.”

(Doc. 24-

1 ¶ 15.)

Mr. Butterworth opined that the swelling and charring

reaction

are

the

defining

characteristics

of

intumescent

substances, further noting that there “is no particular explicit
or unique formulation required for intumescence.

Hence, it is

highly unusual and unnecessary to incorporate a specific chemical
formulation into a general definition of the term ‘intumescent’ as
would be understood by one of ordinary skill in the art.”

(Id.

¶ 17.) 6
Tietex argues that intumescents, being chemicals, are only
properly

defined

properties.

by

their

chemical

composition,

their

In other words, Tietex contends, chemicals ought to

be described as what they are, not how they react.
4.)

not

(Doc. 49 at 2–

But the prosecution history makes clear that the patent

examiner understood that the exact intumescent chemical used in
the invention is not defined.

(See, e.g., Doc. 37-2 at 351

(“Appealed claim 1 [of Patent ’639] does not recite any specific

6

Although the opinion of Tietex’s expert, Dr. Wilkie, is not being
relied upon for claim construction, it is noteworthy that, after he gave
an elaborate definition of an “intumescent,” he agreed that the general
technical definition of “intumescence” is “the property of a material
to swell when heated.” (Wilkie Decl. ¶¶ 30, 32.)

16

materials for the flame retardant agent and intumescent agent.”).) 7
Tietex would be on firmer ground, perhaps, if the patents in fact
claimed just a novel chemical, because the claims could possibly
fail to “enable” one of ordinary skill in the art to make the
invention.

35 U.S.C. § 112(a).

But, in this case, the patents’

specifications only refer to intumescent agents manufactured by
other

companies.

The

claimed

invention

is

not

a

particular

intumescent chemical, but a combination of a certain fabric with
various

types

of

intumescents

available

from

other

vendors.

Moreover, the claims do limit the intumescent chemical to ones
containing phosphorous or nitrogen.

(See, e.g., ’162 Patent col.

12, ll. 11–13; ’639 Patent col. 12, ll. 8–10 (as amended), col.
12, ll. 50–65, col. 13, ll. 2–20, col. 14, ll. 4-5; accord Doc.
41-11 at 8.)
Tietex has implied that a functional definition of a chemical
is improper in patent law, but it has cited no authority for such
a proposition. At the hearing, PFG argued that functional claiming
is generally proper, and there is support for that proposition.
See Manual of Patent Examining Procedure § 2173.05(g) (9th ed.
2014), available at http://www.uspto.gov/web/offices/pac/mpep/in

7

Tietex cites to extrinsic evidence (e.g., invention disclosures and
original patent applications) that merely repeats the “four basic
components” definition of intumescent “systems.” (Doc. 41 at 15–18.)
But because each repetition is still limited to systems and is no more
probative than the specifications themselves, the court is not persuaded
beyond Tietex’s similar arguments about the specifications.

17

dex.html (“A claim term is functional when it recites a feature by
what it does rather than by what it is . . . .

There is nothing

inherently

an

wrong

with

functional terms.

defining

part

of

invention

in

Functional language does not, in and of itself,

render a claim improper.”
omitted)).

some

Numerous

(citation and internal quotation marks

patent

cases

functional definitions of chemicals.

specifically

approve

of

See, e.g., Lab. Skin Care,

Inc. v. Ltd. Brands, Inc., 616 F. Supp. 2d 468, 480 (D. Del. 2009)
(construing patent for moisturizing skin care products, where
claim term “antimicrobial lotion” was construed functionally to
mean “a lotion that effectively inhibits the growth of or kills
microorganisms present on the skin”); Proctor & Gamble Co. v.
McNeil-PPC, Inc., No. 08-CV-251-BBC, 2009 WL 196826, at *8 (W.D.
Wis. Jan. 26, 2009) (construing patent for teeth-whitening strips,
where claim term “gelling agent” was construed functionally to
mean “an agent that has the ability to form a gel”).

Moreover,

the examiner appeared to understand and acquiesce in the functional
definition.

(See Doc. 41-11 at 8 (“It is noted that intumescents

function not just as flame retardants but as thermal barriers.”).)
Tietex cites prior related art and other patents in support
of its contention that a person of ordinary skill would limit the
term intumescent to describing chemicals with the “four basic
components.” But this argument, too, is unavailing. First, United
Kingdom

Patent

2,293,572

(“Rowan”)
18

lists

four

components

of

intumescent materials but teaches that an intumescent “may” be
comprised of these four.

(Doc. 41-20 at 8.)

Second, U.S. Patent

No. 4,061,579 (“Sawko”) is offered to show that intumescents always
have the four basic components.

But Sawko teaches that the

composition of agents can be quite variable.
ll.

25–44

(“Generally,

intumescent

(Doc. 41-21 col. 1,

coating

compositions

are

formulated from a combination of a variety of constituents which
enter into a complex series of reactions when intumesced by heat
or fire. . . .

It is apparent since the intumescent coatings

generally contain a variety of constituents, that the sequence of
reactions which takes place is dependent on the decomposition
temperature of each ingredient which must possess environmental
stability in order to function at the proper temperature.”).)
Finally,

Tietex

argues

that

the

court

should

construe

intumescent narrowly, or else the patents will be invalidated for
failing “to enable one of skill in the art to recreate the
invention.”

(Doc.

41

at

22.)

Indeed,

a

canon

of

claim

construction directs courts to avoid invalidating definitions —
but Tietex seeks too much of the canon here.

See Phillips, 415

F.3d at 1327 (“While we have acknowledged the maxim that claims
should be construed to preserve their validity, we have not applied
that principle broadly, and we have certainly not endorsed a regime
in

which

validity

construction.”).

analysis

is

a

regular

component

of

claim

The canon only applies when, after exhaustion of
19

all other tools, the disputed claim term remains ambiguous.

Id.

But, in this case, the ordinary meaning of “intumescent” is clear
without use of this narrow canon.

And, were the court to rely on

the canon, the effort would be fruitless because Tietex has made
only conclusory allegations of invalidity.

The company has not

offered, at this point, any legal reason why PFG’s construction
would result in invalidity.
The Federal Circuit has explained that “[t]he construction
that stays true to the claim language and most naturally aligns
with the patent’s description of the invention will be, in the
end, the correct construction.”

Renishaw PLC v. Marposs Societa’

per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998).
bound

to

accept

either

party’s

proposed

Although not

construction

of

“intumescent,” and having considered and properly weighted all of
the intrinsic and extrinsic evidence presented, the court is
persuaded that PFG’s construction is correct.

The court therefore

construes the claim term “intumescent” to describe “a substance
that swells and chars upon exposure to heat or flame.”
III. CONCLUSION
For the reasons stated,
IT IS ORDERED that PFG’s motion to strike (Doc. 38) is DENIED,
but the opinion of Dr. Wilkie will not be considered, and the
disputed claim term “intumescent” from the ’162 and ’639 patents
is construed to describe “a substance that swells and chars upon
20

exposure to heat or flame.”
/s/
Thomas D. Schroeder
United States District Judge
January 15, 2015

21