UNITED STATES DEPARTMENT OF COMMERCE
`United States Patent and Trademarli Office
`
`April 04, 2016
`
`THIS IS TO CERTIFY THAT ANNEXED IS A TRUE COPY FROM THE
`RECORDS OF THIS OFFICE OF THE FILE WRAPPER AND CONTENTS
`OF:
`
`APPLICATION NUMBER: 101876,103
`FILING DATE: June 23, 2004
`PATENT NUMBER: 7,399,439
`ISSUE DATE: July 15,2008
`
`By Authority of the
`Under Secretary of Commerce for Intellectual Property
`and Director of the United States Patent and Trademark Office
`
`;:~~? ~} -~~--G
`P.R. GRANT
`Certifying Officer
`
`ASPEN0000390
`
`ALISON – Ex. 1002 - Part 1
`Alison v. Aspen
`IPR2017-00201
`
`

`
`UTILITY PATENT APPLICATION TRANSMITTAL
`(Small Entity)
`(Only for new nonprovisional applications under 37 CFR 1.53(b))
`
`Docket No.
`59482 (46775)
`
`Total Pages in this Submission
`4
`
`0
`1-(1')
`~0
`(/) ,_
`P.O. Box 1450
`::::>~
`Alexandria, VA 22313-1450
`Transmitted herewith for filing under 35 U.S.C. 111 (a) and 37 C.F.R. 1.53(b) is a new utility patent application for arr-. ~
`~ 0
`invention entitled:
`
`"'J
`
`[ MEmoos ro PRODUCE GEL Sm:ETS
`
`and invented by:
`
`Kang P. LEE, George L. GOULD, William GRONEMEYER and Christopher John STEPANIAN
`
`This application claims~priority to U. S. Provisional Application No. 60/482,359
`filed June 24, 2003.
`Which is a:
`0 Continuation 0 Divisional 0 Continuation-in-part (CIP) of prior application No.:
`Which is a:
`0 · Continuation 0 Divisional 0 Continuation-in-part (CIP) of prior application No.:
`
`Enclosed are:
`
`Application Elements
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`1. 181 Filing fee as calculated and transmitted as described below
`
`2.
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`l8l Specificati9n having _____ 3_3 ____ pages and including the following:
`
`a. 181 Descriptive Title of the Invention
`
`b. 181 Cross References to Related Applications (if applicable)
`
`c. 0 Statement Regarding Federally-sponsored Research/Development (if applicable)
`
`d. 0 Reference to Sequence Listing, a Table, or a Computer Program listing Appendix
`
`e. ~ Background of the Invention
`
`f. l8l Brief Summary of the Invention
`
`g. 181 Brief Description of the Drawings (if filed)
`
`h. 181 Detailed Description
`
`i. ~ Claim(s) as Classified Below
`j . 181 Abstract of the Disclosure
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`Page I of4
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`ASPEN0000391
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`
`UTILITY PATENT APPLICATION TRANSMITTAL
`(Small Entity)
`(Only for new nonprovisional applications under 37 CFR 1.53(b))
`
`Docket No.
`59482 (46775)
`
`II
`Total Pages in this Submission
`4
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`3.
`
`Application Elements (Continued)
`181 Drawing{s) (when necessary as prescribed by 35 USC 113)
`a. IZl Formal
`Number of Sheets
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`4. 0 Oath or Declaration
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`0 Unexecuted
`b. 0 Copy from a prior application (37 CFR 1.63(d)) (for continuation/divisional application only)
`c. 0
`0 Without Power of Attorney
`~ith Power of Attorney
`d. 0 DELETION OF INVENTOR(S)
`Signed statement attached deleting inventor(s) named in the prior application,
`see 37 C.F.R. 1.63(d)(2) and 1.33(b).
`
`5. 0
`
`Incorporation By Reference (usable if Box 4b is checked)
`The entire disclosure of the prior application, from which a copy of the oath or declaration is supplied under
`Box 4b, is considered as being part of the disclosure of the accompanying application and is hereby
`incorporated by reference therein.
`
`6. 0 CD ROM or CD-R in duplicate, large table or Computer Program (Appendix)
`7. 0 Application Data Sheet (See 37 CFR 1.76)
`8. 0 Nucleotide and/or Amino Acid Sequence Submission (if applicable, all must be included)
`
`a. 0 Computer Readable Form (CFR)
`b. 0 Specification Sequence Listing on:
`i. 0 CD-ROM or CD-R (2 copies); or
`ii. 0 Paper
`c. 0 Statement(s) Verifying Identical Paper and Computer Readable Copy
`
`Accompanying Application Parts
`
`9.
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`10.
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`11 .
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`12.
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`13.
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`14.
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`15.
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`16.
`
`0
`0
`0
`0
`0
`181
`0
`181
`
`Assignment Papers (cover sheet & document(s))
`
`37 CFR 3.73(B) Statement (when there is an assignee)
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`English Translation Document (if applicable)
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`Information Disclosure StatemenUPT0-1449
`
`0 Copies of IDS Citations
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`Preliminary Amendment
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`Return Receipt Postcard (MPEP 503) (Should be specifically itemized)
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`First Class
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`181 Express Mail (Specify Label No.): EV438978260US
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`Page 2 of 4
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`UTILITY PATENT APPLICATION TRANSMITTAL
`(Small Entity)
`(Only for new nonprovisional applications under 37 CFR 1.53(b))
`
`Docket No.
`59482 (46775)
`
`II
`Total Pages in this Submission
`4
`
`Accompanying Application Parts (Continued)
`
`17. 181 Applicant claims small entity status. See 37 CFR 1.27.
`0
`(Optional) Small Entity Statement(s)- Specify Number of Statements Submitted:
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`18. 0 Additional Enclosures (please identify below):
`
`Request That Application Not Be Published Pursuant To 35 U.S.C. 122(b)(2)
`
`19. 0 Pursuant to 35 U.S.C. 122(b)(2), Applicant hereby requests that this patent application not be
`published pursuant to 35 U.S.C. 122(b)(1). Applicant hereby certifies that the invention disclosed in
`this application has not and will not be the subject of an application filed in another country, or under
`a multilateral international agreement, that requires publication of applications 18 months after filing
`of the application.
`
`Warning
`
`An applicant who makes a request not to publish, but who subsequently files in a foreign
`country or under a multilateral international agreement specified in 35 U.S. C. 122(b)(2){B){i),
`must notify the Director of such filing not later than 45 days after the date of the filing of
`such foreign or international application. A failure of the applicant to provide such notice
`within the prescribed period shall result in the application being regarded as abandoned,
`unless it is shown to the satisfaction of the Director that the delay in submitting the notice
`was unintentional.
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`Pag~J of4
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`~ g UTILITY PATENT APPLICATION TRANSMITTAL
`~ I ~
`(Small Entity)
`.:::.. ~ ~ (Only for new nonprovisional applications under 37 CFR 1.53(b))
`
`Docket No.
`59482 (46775)
`
`Total Pages in this Submission
`4
`
`Fee Calculation and Transmittal
`
`CLAIMS AS FILED
`
`For
`
`#Filed
`
`#Allowed
`
`#Extra
`
`Total Claims
`
`lndep. Claims
`
`52
`
`7
`
`-20 =
`- 3 =
`
`32
`
`4
`
`X
`
`X
`
`Multiple Dependent Claims (check if applicable)
`
`181
`
`Rate
`
`$9.00
`
`$43.00
`
`OTttER FEE (specify purpose)
`
`BASIC FEE
`
`TOTAL FILING FEE
`
`Fee
`
`$288.00
`
`$172.00
`
`$145.00
`
`$385.00
`
`$0.00
`
`$990.00
`
`181 A check in the amount of
`to cover the filing fee is enclosed.
`$990.00
`181 The Director is hereby authorized to charge and credit Deposit Account No.
`as described below.
`0 Charge the amount of
`181 Credit any overpayment.
`181 Charge any additional filing fees required under 37 C.F.R. 1.16 and 1.17.
`t~e Nolie of~AIIowance,
`0 Charge the issue fee set in 37 C.F.R. 1.18 at the maili1Uanof
`pursuantto37C.F.R.1 .311(b).
`
`as filing fee.
`
`04-1105
`
`Dated:
`
`June 23, 2004
`
`Customer No: 21874
`
`cc:
`
`!J/,_ ()
`rw.r--
`
`Signature
`
`Richard J. Roos, Esq. (Reg. No. 45,053)
`EDWARDS & ANGELL, LLP
`P.O. Box 55874
`Boston, Massachusetts 02205
`Phone: (617) 439-4170
`Fax: (617) 439-4170
`
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`CERTIFICATE OF MAILING BY "EXPRESS MAIL" (37 CFR 1.10)
`Applicant(s): K.P. LEE et al.
`
`Docket No.
`
`59482 (46775)
`
`Serial No.
`Not Yet Assigned
`
`Filing Date
`Filed Herewith
`
`Examiner
`Not Yet Assigned
`
`Group Art Unit
`Not Yet Assigned
`
`Invention:
`
`METHODS TO PRODUCE GEL SHEETS
`
`I hereby certify that the following correspondence:
`
`Utility Patent Application Transmittal, Utility Patent Application, Check in the amount of $990.00, Certificate of
`Express Mail and Return Receipt Postcard.
`
`is being deposited with the United States Postal Service "Express Mail Post Office to Addressee" service under 37
`
`CFR 1.10 in an envelope addressed to: Commissioner for Patents, P.O. Box 1450, Alexandria, VA 22313-1450 on
`
`(Identify type of correspondence)
`
`June 23, 2004
`(Date)
`
`Lee Dunkle
`(Typed or Printed Name of Person Mailing Correspondence)
`
`rsl2:itiJ~tll!;;;_,•uJ
`
`EV 438978260US
`("Express Mail" Mailing Label Number)
`
`Note: Eacb paper must bave Us own certificate of mailing.
`
`P06A/REV02
`
`ASPEN0000395
`
`

`
`Attorney Docket No.: 59482(46775)
`Express Mail Label No.: EV438978260US
`
`METHODS TO PRODUCE GEL SHEETS
`
`CROSS REFERENCE TO RELATED APPLICATIONS
`
`This application claims the priority from, and incorporates the entirety of pending
`
`5 U.S. Provisional Patent Application Serial Number 60/482,359, which is entitled "Methods
`
`for producing Gel Sheets," and which filed on June 24,2003.
`
`BACKGROUND OF THE INVENTION
`
`FIELD OF THE INVENTION
`
`10
`
`This invention relates to the preparation of solvent filled gel sheets in a continuous
`
`fashion. Such gel sheets are used in manufacturing aerogel blankets, aerogel composites, aerogel
`
`monoliths and other aerogel based products.
`
`DESCRIPTION OF RELATED ART
`
`15
`
`Aerogels describe a class of material based upon their structure, namely low density,
`
`open cell structures, large surface areas (often 900 m2/g or higher) and sub-nanometer scale
`
`pore sizes. Supercritical and subcritical fluid extraction technologies are commonly used to
`
`extract the fluid from the fragile cells of the material. A variety of different aerogel
`
`compositions are known and may be inorganic or organic. Inorganic aerogels are generally
`
`20
`
`based upon metal alkoxides and include materials such as silica, carbides, and alumina.
`
`Organic aerogels include, but are not limited to, urethane aerogels, resorcinol formaldehyde
`
`aerogels, and polyimide aerogels.
`
`Low-density aerogel materials (O.oJ -0.3 glee) are widely considered to be the best
`
`solid thermal insulators, better than the best rigid foams with thermal conductivities of 10-15
`
`25 mW/m-K and below at 100° F and atmospheric pressure. Aerogels function as thermal
`
`insulators primarily by minimizing conduction (low density, tortuous path for heat transfer
`
`through the solid nanostructure), convection (very small pore sizes minimize convection), and
`
`radiation (ffi.. absorbing or scattering dopants are readily dispersed throughout the aerogel
`
`matrix). Depending on the formulation, they can function well at cryogenic temperatures to
`
`30
`
`550° C and above. Aerogel materials also display many other interesting acoustic, optical,
`
`mechanical, and chemical properties that make them abundantly useful.
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`ASPEN0000396
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`

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`Low-density insulating materials have been developed to solve a number of thermal
`
`isolation problems in applications in which the core insulation experiences significant
`
`compressive forces. For instance, polymeric materials have been compounded with hollow .
`
`glass microspheres to create syntactic foams, which are typically very stiff, compression
`
`5
`
`resistant materials. Syntactic materials are well known as insulators for underwater oil and
`
`gas pipelines and support equipment. Syntactic materials are relatively inflexible and of high
`
`thermal conductivity relative to flexible aerogel composites (aerogel matrices reinforced by
`
`fiber). Aerogels can be formed from flexible gel precursors. Various flexible layers,
`
`including flexible fiber-reinforced aerogels, can be readily combined and shaped to give pre-
`
`1 0
`
`forms that when mechanically compressed along one or more axes, give compressively strong
`
`bodies along any of those axes. Aerogel bodies that are compressed in this manner exhibit
`
`much better thermal insulation values than syntactic foams. Methods to produce these
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`materials rapidly will facilitate large-scale use of these materials in underwater oil and gas
`
`pipelines as external insulation.
`
`15
`
`Conventional methods for gel sheet and/or fiber-reinforced composite gel sheet
`
`production formed via sol-gel chemistry described in the patent and scientific literature
`
`invariably involve batch casting. Batch casting is defined here as catalyzing one entire volume
`
`of sol to induce gelation simultaneously throughout that volume. Gel-forming techniques are
`
`well-known to those trained in the art: examples include adjusting the pH and/or temperature
`
`20
`
`of a dilute metal oxide sol to a point where gelation occurs (R. K. Tier, Colloid Chemistry of
`
`Silica and Silicates, 1954, chapter 6; R. K. Iler, The Chemistry of Silica, 1979, chapter 5, C. J.
`
`Brinker and G. W. Scherer, Sol-Gel Science, 1990, chapters 2 and 3).
`
`U.S. Patent No. 6,068,882 (Ryu) discloses an example of a fiber-reinforced aerogel
`
`composite material that can be practiced with the embodiments of the present invention. The
`
`25
`
`preferred aerogel composite precursor materials used in the present invention are those like
`
`Cryogel®, Pyrogel®, or Spaceloft"' sold commercially by Aspen Aerogels, Incorporated. U.S.
`
`Patent No. 5,306,555 (Ramamurthi et al.) discloses an aerogel matrix composite of a bulk
`
`aerogel with fibers dispersed within the bulk aerogel and a method for preparing the aerogel
`
`matrix composite.
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`30
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`-2-
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`SUMMARY OF THE INVENTION
`
`This invention describes continuous and semi-continuous sol-gel casting methods that
`
`are greatly improved over conventional batch sol-gel casting methods for gel sheets, fiber(cid:173)
`
`reinforced flexible gel sheets, and rolls of composite gel materials.
`
`5
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`More specifically, the invention describes methods for continuously combining a low
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`viscosity solution of a sol and an agent (heat catalyst or chemical catalyst) that induces gel
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`formation and forming a gel sheet on a moving element such as a conveyer belt with edges
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`that defines the volume of the formed gel sheet by dispensing the catalyzed sol at a
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`predetermined rate effective to allow gelation to occuer on the moving element. The sol
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`10
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`includes an inorganic, organic or a combination of inorganic/organic hybrid materials. The
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`inorganic materials include zirconia, yttria, hafuia, alumina, titania, ceria, and silica,
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`magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, and any
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`combinations of the above. Organic materials include polyacrylates, polyolefins, polystyrenes,
`
`polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol furfuryl alcohol,
`
`15 melamine formaldehydes, resorcinol formaldehydes, cresol formaldehyde, phenol
`
`formaldehyde, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various
`
`epoxies, agar, agarose and any combinations of the above. Even more specifically, the
`
`methods describe the formation of monolithic gel sheets or fiber-reinforced gel composite
`
`having two parts, namely reinforcing fibers and a gel matrix wherein the reinforcing fibers are
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`20
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`in the fonn of a lofty fibrous structure (i.e. batting), preferably based upon either
`
`thermoplastic polyester or silica fibers, and more preferably in combination with individual
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`randomly distributed short fibers (microfibers) in a continuous or semi-continuous fashion.
`
`The fibrous batting or mat material is introduced onto th emoving element for combination
`
`with the catalyzed sol prior to gelation.
`
`25
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`Moreover, when a gel matrix is reinforced by a lofty batting material, particularly a
`
`continuous non-woven batting comprised of very low denier fibers, the resulting composite
`
`material when dried into an aerogel or xerogel product by solvent extraction, maintains
`
`similar thermal properties to a monolithic aerogel or xerogel in a much stronger, more durable
`
`form. The diameter of the fibers used is in the range of0.1-10,000 microns. In some cases
`
`30
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`nanofibers in the range ofO.OOl to 100 microns are used in reinforcing the gel. In addition to
`
`the fiber batting, crimped fibers can be distributed throughout the gel structure.
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`Even more specifically, the methods describe methods to continuously or semi(cid:173)
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`continuously form gel composites by introduction of an energy dissipation zone on the
`
`moving conveyor apparatus. The gelation of the catalyzed sol can be enhanced by chemical
`
`or energy dissipation process. For instance, a controlled flux of electromagnetic (ultraviolet,
`
`5
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`visible, infrared, microwave), acoustic (ultrasound), or particle radiation can be introduced
`
`across the width of a moving sol volume contained by a conveyor belt to induce sufficient
`
`cross-linking of the polymers contained within the sol to achieve a gel point. The flux, the
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`point and the area of radiation can be controlled along the conveyance apparatus to achieve an
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`optimized casting rate and desirable gel properties by the time the terminus of the conveyor is
`
`10
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`reached for a given section of gel. In this fashion, gel properties can be controlled in a novel
`
`fashion to a degree not possible with batch casting methods. In addition, another moving
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`element rotating in the opposite direction to the first moving element can be used to provide
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`the shape of the top portion of the gel sheets.
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`Still more specifically, a roll of gel composite material that is co-wound or corolled
`
`15 with a porous flow layer that facilitates solvent extraction using supercritical fluids
`
`processing methods can be formed in a very small footprint using the method of the present
`
`invention. This is accomplished via infusing a predetermined amount of catalyzed sol in a
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`rolled fiber-preform co-rolled with an impermeable spacer layer, geling the infused roll,
`
`followed by un-rolling the gel composite article, removing the impermeable layer, and re-
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`20
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`rolling of the incompletely cured body flexible gel composite with a porous spacer layer. The
`
`method described in this invention provides great advantage in enhancing the rate of
`
`production of gel composite materials in as small an area as possible.
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`Still more specifically, a method for producing gel sheets in a continuous fashion is
`
`described in which gel sheets are produced by any one of th eabove mentioned methods and
`
`25
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`are rolled into a plurality of layers. This is a novel and effective way of producing gel sheets
`
`for efficient drying operations. In another feature, an optional spacer material is co-rolled with
`
`the gel sheets. Such a spacer material can be permeable or impermeable in nature. Depending
`
`on the permeability of the spacer material, one can obtain a favorable flow pattern in a
`
`subsequent drying. Spacer material also provides flow paths for subsequent silation (aging)
`
`30
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`fluids to easily pass through. In the drying they further help by proving flow paths that
`
`effectively reduce the thickness of the gel sheet to be extracted in in radial direction.
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`These and still further embodiments of the present invention are described in greater
`
`detail below. The advantages of the methods described in this invention for processing
`
`monolith and fiber-reinforced composite sheets in a continuous or semi-continuous fashion
`
`over previously described methods are many. For instance, the gel articles can be fashioned
`
`5
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`continuously or semi-continuously provided all components are fed into the apparatus at the
`
`appropriate rate. Thus, large volumes of material can be fashioned in a smaller production
`
`area than with traditional batch casting requiring molds that must be filled and allowed to set
`
`for aging prior to solvent extraction to make aerogel or xerogel materials. Very long
`
`continuous sheets of fiber-reinforced, flexible gel material are readily fashioned using the
`
`10 methods of this invention because of the combined casting and rolling processing allows a
`
`single molding surface to be continuously re-utilized within a small production area. When
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`rolls of gel are cast batch wise followed by roll-to-roll processing to place porous flow layers
`
`between layers of gel material, the production footprint is diminished even further, increasing
`
`production capacity and potentially lowering production costs relative to flat sheet batch casting.
`
`15
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates a method of producing fiber reinforced gel sheets using a counter
`
`rotating conveyor belt.
`
`FIG. 2 illustrates a method of producing fiber reinforced gel sheets using a single
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`20
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`rotating conveyor belt.
`
`FIG. 3 illustrates a method of producing fiber reinforced gel sheets using a counter
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`rotating conveyor belt with additional cutting.
`
`FIG. 4 illustrates a method of producing fiber reinforced gel sheets using a single
`
`rotating conveyor belt with additional cutting.
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`25
`
`FIG. 5 illustrates the general flow diagram of catalyst-sol mixing prior to casting.
`
`FIG. 6 illustrates an additional embodiment with dispensing the catalyzed sol to a
`
`preformed roll including spacer layers.
`
`FIG. 7 illustrates an additional embodiment for producing gel sheet by inducing a
`
`gelation zone.
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`30
`
`FIG. 8 illustrates an additional embodiment for producing gel sheets with one or more
`
`spacer layers.
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`DET A.ll.ED DESCRIPTION OF THE INVENTION
`
`The invention(s) described herein are directed to producing solvent filled,
`
`nanostructured gel monolith and flexible blanket composite sheet materials. These materials
`
`give nanoporous aerogel bodies after all mobile phase solvents are extracted using a
`
`5
`
`hypercritical solvent extraction (supercritical fluid drying). For instance, the processes
`
`described in this invention will offer significantly better production capacities for forming
`
`monolithic gel sheets or rolled gel composite articles in a form factor that will facilitate
`
`removal of solvent in a subsequent supercritical fluids extraction procedure. The first method
`
`outlines a conveyor-based system that utilizes delivery of a low viscosity, catalyzed sol
`
`I 0 mixture at one end and a system to cut and convey formed monolithic (defined here as
`
`polymer or ceramic solid matrix only, no fibers added) sheets of solvent filled gel material
`
`into a system for further chemical treatment. The second method describes a conveyor-based
`
`system that utilizes delivery of a catalyzed sol mixture of low viscosity at one end and a
`
`system to cut and convey solvent-filled, fiber-reinforced gel composite sheets into a rolling
`
`15
`
`system (with and without a porous separator flow layer) to produce a form factor ready for
`
`further treatment prior to supercritical fluid extraction. The third method describes a direct
`
`roll-to-roll transfer process between two canisters in which the first hosts a direct "gel in a
`
`roll" reaction followed by unrolling and re-rolling the gel with a porous separator flow layer
`
`to prepare the form factor for further treatment prior to supercritical extraction. The three
`
`20 methods may be used in conjunction with controlled energy delivery methods to facilitate the
`
`timing of gelation and the strength of the green bodies formed. Energy in the form of
`
`ultrasound, heat, and various forms of radiation can be used to induce gelation from a
`
`prepared sol mixture in addition to classical methods of chemical catalysis (such as in a pH
`
`change from a stable sol pH to one that facilitates gelation.
`
`25
`
`The matrix materials described in this invention are best derived from sol-gel
`
`processing, preferably composed of polymers (inorganic, organic, or inorganic/organic
`
`hybrid) that define a structure with very small pores (on the order of billionths of a meter).
`
`Fibrous materials added prior to the point of polymer gelation reinforce the matrix materials
`
`described in this invention. The preferred fiber reinforcement is preferably a lofty fibrous
`
`30
`
`structure (batting or web), but may also include individual randomly oriented short
`
`microfibers, and woven or non-woven fibers. More particularly, preferred fiber
`
`-6-
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`reinforcements are based upon either organic (e.g. thermoplastic polyester, high strength
`
`carbon, aramid, high strength oriented polyethylene), low-temperature inorganic (various
`
`metal oxide glasses such as E-glass), or refractory (e.g. silica, alumina, aluminum phosphate,
`
`aluminosilicate, etc.) fibers. The thickness or diameter of the fiber used in the embodiments
`
`5
`
`of the present invention is in the range ofO.l to 10,000 micron, and preferably in the range of
`
`0.1 to 100 micron. In another preferred embodiment nanostructures fibers as small as 0.001
`
`micron are used to reinforce the gel. Typical examples include carbon nanofibers and carbon
`
`nanotubes with diameters as small as 0.001 microns. Solvent filled gel sheets combining a
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`ceramic solid (e.g. silica) and a mobile solvent phase (e.g. ethanol) can be formed on a
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`conveyor by continuous injection of a catalyst phase into a sol phase and dispersing the
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`catalyzed mixture onto a moving conveyor. Such materials will find use in insulating
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`transparencies, such as double-glazing windows in buildings. Because these gel materials are
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`normally stiff and inflexible when they are composed of a ceramic or cross-linked polymer
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`matrix material with intercalated solvent (gel solvent) in the absence of fiber reinforcement,
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`these materials need to be handled as molded if they are continuously cast. If the conveyor
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`has molded edges that retain volume, then the gel can be directly cast onto the conveyor
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`surface. If the conveyor has molds placed upon it, then the mold volumes can be
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`continuously filled with freshly catalyzed sol.
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`Suitable materials for forming inorganic aerogels are oxides of most of the metals that
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`can form oxides, such as silicon, aluminum, titanium, zirconium, bafuiurn, yttrium,
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`vanadium, and the like. Particularly preferred are gels formed primarily from alcohol
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`solutions of hydrolyzed silicate esters due to their ready availability and low cost (alcogel).
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`Organic aerogels can be made from polyacrylates, polystyrenes, polyacrylonitriles,
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`polyurethanes, poly-imides, polyfurfural alcohol, phenol furfuryl alcohol, melamine
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`formaldehydes, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde,
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`polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar,
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`agarose, and the like (see for instance C. S. Ashley, C. J. Brinker and D. M. Smith, Journal of
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`Non-Crystalline Solids, volume 285, 2001).
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`In one preferred embodiment of the methods of this invention, energy dissipation
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`through a portion of the sol volume is utilized in a specific location of a conveyor apparatus
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`utilized for the gel casting. By controlling the area of the catalyzed sol that is exposed to heat
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`or specific flux of radiation (e.g. ultrasonic, x-ray, electron beam, ultraviolet, visible, infrared,
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`microwave, gamma ray), a gelation phenomenon can be induced at a given point of a
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`conveyor apparatus. It is advantageous to control the timing of the gelation point with respect
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`to the conveyor speed such that the material has adequate time to age and strengthen prior to
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`any mechanical manipulation at the terminus of the conveyor apparatus. Although the
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`diffusion of polymer chains and subsequent solid network growth are significantly slowed
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`within the viscous gel structure after the gelation point, the maintenance of the original gel
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`liquid (mother liquor) for a period of time after gelation is essential to obtaining an aerogel
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`that has the best thermal and mechanical properties. This period of time that the gel "ages"
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`10 without disturbance is called "syneresis". Syneresis conditions (time, temperature, pH, solid
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`concentration) are important to the aerogel product quality.
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`Gels are a class of materials formed by entraining a mobile interstitial solvent phase
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`within the pores of a solid structure. The solid structures can be composed of inorganic,
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`organic or inorganic/organic hybrid polymer materials that develop a pore morphology in
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`direct relation to the method of gelation, solvent-polymer interactions, rate of polymerization
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`and cross-linking, solid content, catalyst content, temperature and a number of other factors.
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`It is preferred that gel materials are formed from precursor materials, including various fiber(cid:173)
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`reinforcement materials that lend flexibility to the formed composite, in a continuous or semi(cid:173)
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`continuous fashion in the form of sheets or rolls of sheets such that the interstitial solvent
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`phase can be readily removed by supercritical fluids extraction to make an aerogel material.
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`By keeping the solvent phase above the critical pressure and temperature during the entire, or
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`at minimum the end of the solvent extraction process, strong capillary forces generated by
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`liquid evaporation from very small pores that cause shrinkage and pore collapse are not
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`realized. Aerogels typically have low bulk densities (about 0.15 glee or less, preferably about
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`0.03 to 0.3 glee), very high surface areas (generally from about 300 to 1,000 m2/g and higher,
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`preferably about 700 to 1000 m2/g), high porosity (about 90% and greater, preferably greater
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`than about 95%), and relatively large pore volume (about 3 mUg, preferably about 3.5 mUg
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`and higher). The combination of these properties in an amorphous structure gives the lowest
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`thermal conductivity values (9 to 16 mW/m-K at 37° C and 1 atmosphere of pressure) for any
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`coherent solid material.
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`The monolithic and composite gel material casting methods described in the present
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`invention comprise three distinct phases. The first is blending all constituent components
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`(solid precursor, dopants, additives) into a low-viscosity sol that can be dispensed in a
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`continuous fashion. The second involves dispensing the blended sol onto a moving conveyor
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`5 mold that may also have a synchronized counter-rotating top belt to form a molded upper
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`surface. The second phase may also include introduction of heat or radiation to the ungelled
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`sol within a defined area of the moving conveyor apparatus to either induce gelation or
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`modify the properties of the gel such as gel modulus, tensile strength, or density. The third
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`phase of the invention process involves gel cutting and conveyance of monolithic gel sheets
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`to a post-processing area or co-rolling a flexible, fiber-reinforced gel composite with ~
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`flexible, porous flow layer to generate a particularly preferred form factor of the material.
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`The formed rolls of gel composite material and flow layer are particularly amenable to
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`interstitial solvent removal using supercritical processing methods. An example of the
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`preferred gel casting method is shown in Figure I, which utilizes a conventional chemically
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`catalyzed sol-gel process in combination with a moving conveyor apparatus with counter(cid:173)
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`rotating molding capability. The fiber-reinforced, nanoporous gel composite can be
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`mechanically rolled, with or without a porous flow layer, as shown in Figure I. Figure 2
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`shows the same process utilizing a moving conveyor belt with only a single molding surface
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`(a continuously rotating bottom belt with molded sides). Figure 3 shows how monolithic gel
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`sheets, formed from a polymer sol (without added fiber reinforcing structures) can be formed
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`continuously by deposition of a catalyzed sol solution onto a moving conveyor, and Figure 4
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`illustrates the same procedure except a counter-rotating conveyor molding strategy is shown.
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`The sols utilized in this invention are mixed and prepared, often by co-mixing with a
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`chemical catalyst, prior to deposition onto the moving conveyor as shown in the block
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`diagram ofFigure 5. A related, but alternative embodiment of the invention process is shown
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`in Figure 6, in which a fiber and separator layer preform roll are infiltrated with a sol, and
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`after initial gelation takes place, unrolled to separate the gel composite from the impermeable
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`layer and subsequently re-rolled with a permeable layer to prepare for further chemical
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`processing.
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`The gel matrix of the preferred precursor materials for the present invention may be
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`organic, inorganic, or a mixture thereof. Sols can be catalyzed to induce gelation by methods
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`known to those trained in the art: examples include adjusting the pH and/or temperature of a
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`dilute metal oxide sol to a point where gelation occurs (The following are incorporated here
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`by reference: R. K. Tier, Colloid Chemistry of Silica and Silicates, 1954, chapter 6; R. K. Tier,
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`The Chemist