U.S. patent application number 14/041508 was filed with the patent office on 2015-04-02 for methods for forming functionalized carbon black with amino-terminated polyfluorodimethylsiloxane for printing.
This patent application is currently assigned to XEROX CORPORATION. The applicant listed for this patent is XEROX CORPORATION. Invention is credited to Santokh S. BADESHA, David J. GERVASI, Anton GRIGORYEV, Mandakini KANUNGO.
Application Number | 20150092004 14/041508 |
Document ID | / |
Family ID | 52739753 |
Filed Date | 2015-04-02 |
United States Patent
Application |
20150092004 |
Kind Code |
A1 |
KANUNGO; Mandakini ; et
al. |
April 2, 2015 |
METHODS FOR FORMING FUNCTIONALIZED CARBON BLACK WITH
AMINO-TERMINATED POLYFLUORODIMETHYLSILOXANE FOR PRINTING
Abstract
A method for forming functionalized carbon black useful for
uniform dispersion in a surface material of a printing system
component includes providing carbon black; providing a
fluoropolymer having a terminal amino group; and mixing the
amino-terminated fluoropolymer and the carbon black, wherein the
fluoropolymer is amino-terminated PDMS.
Inventors: |
KANUNGO; Mandakini;
(Penfield, NY) ; GRIGORYEV; Anton; (Webster,
NY) ; GERVASI; David J.; (Pittsford, NY) ;
BADESHA; Santokh S.; (Pittsford, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XEROX CORPORATION |
Norwalk |
CT |
US |
|
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
52739753 |
Appl. No.: |
14/041508 |
Filed: |
September 30, 2013 |
Current U.S.
Class: |
347/225 ;
556/419 |
Current CPC
Class: |
B41M 1/06 20130101; B41N
2210/14 20130101; C07F 7/18 20130101; B41N 10/00 20130101; C09D
11/037 20130101; B41J 2/435 20130101; C09D 11/106 20130101; G03G
9/0904 20130101; B41N 2210/10 20130101; B41M 5/0256 20130101 |
Class at
Publication: |
347/225 ;
556/419 |
International
Class: |
C07F 7/18 20060101
C07F007/18; B41J 2/435 20060101 B41J002/435 |
Claims
1. A method for forming functionalized carbon black useful for
uniform dispersion in a surface material of printing system
components, comprising: providing carbon black; providing a
fluoropolymer having a terminal amino group; and mixing the
amino-terminated fluoropolymer and the carbon black, wherein in the
fluoropolymer is amino-terminated PDMS.
2. (canceled)
3. The method of claim 1, comprising: providing a coupling agent
for the mixing.
4. The method of claim 3, wherein the coupling agent is
N,N'-dicyclohexylcarbodiimide.
5. The method of claim 1, comprising: providing nitric acid; mixing
the carbon black with the nitric acid to oxidize a surface of the
carbon black whereby oxidized carbon black is formed.
6. The method of claim 5, wherein the mixing carbon black with the
nitric acid comprises mixing for seven hours.
7. The method of claim 5, wherein the mixing carbon black with the
nitric acid comprises mixing at room temperature.
8. The method of claim 5, comprising: washing the oxidized carbon
black with deionized water until a pH of the carbon black in
solution is 5.
9. The method of claim 8, comprising: drying the carbon black using
vacuum at 150 degrees Celsius for one hour.
10. The method of claim 9, the mixing the amino-terminated
fluoropolymer and the carbon black further comprising the carbon
black being the vacuum dried, oxidized carbon black.
11. The method of claim 10, comprising the amount of dried,
oxidized carbon black lying in a range of 0.5 g to 1.0 g, the
amount of amino-terminated fluoropolymer being 10 g, and an amount
of the coupling agent being 1 g.
12. The method of claim 10, comprising: mixing trifluorotoluene
with the dried, oxidized carbon black before adding the
amino-terminated fluoropolymer to the carbon black and the coupling
agent.
13. The method of claim 12, comprising: washing the functionalized
carbon black with trifluorotoluene for removing residual EF and/or
coupling agent; and evaporating the trifluorotoluene after the
washing.
14. The method of claim 13, comprising the washing being conducted
using an ultracentrifuge.
15. The method of claim 13, comprising the evaporating being
conducted using a vacuum oven.
16. A method for forming an imaging member having a functionalized
carbon black filler component in a surface thereof, comprising:
providing carbon black; providing a fluoropolymer having a terminal
amino group; and mixing the amino-terminated fluoropolymer and the
carbon black, wherein in the fluoropolymer is amino-terminated
PDMS.
17. (canceled)
18. An imaging member useful for ink-based digital printing,
comprising: an imaging surface, the imaging surface comprising
functionalized carbon black, the carbon black being substantially
uniformly dispersed in the imaging surface and having a
fluoropolymer functional group on the imaging surface thereof,
wherein in the fluoropolymer is amino-terminated PDMS.
19. (canceled)
Description
FIELD OF DISCLOSURE
[0001] The disclosure relates to functionalized carbon black
fluoropolymers for printing applications. In particular, the
disclosure relates to methods for forming functionalized carbon
black having amino-terminated polyfluorodimethylsiloxane useful for
printing applications such as for use in a surface material of an
imaging member of an ink-based digital printing system, or for
other printing systems, which may include intermediate transfer
member, toner printing, and fusing systems.
BACKGROUND
[0002] Ink-based digital printing has emerged to capture the short
run and variable data aspect of the offset printing business while
still enjoying the print quality and low run cost. Ink-based
digital printing is discussed by way of example. Features of
ink-based digital printing include: (a) applying dampening fluid to
the imaging member, the surface of which may include an infra-red
(IR) laser-absorbing material, for example, carbon black in an
elastomer, (b) patterning the dampening fluid to form a latent
image using a laser imaging system, which may include, for example,
an IR laser, (c) developing the latent image with offset ink
applied to the imaging member surface, (d) transferring the digital
ink image to paper, and (e) fixing the image on a substrate such as
paper, card stock, plastic, or another printable medium.
[0003] Fluorosilicones are exemplary materials useful for meeting
the material requirements of the imaging member surface. Further,
the imaging member surface may include IR absorbing material to
facilitate digital evaporation of the dampening fluid, and carbon
black is an exemplary material useful for a primary IR absorbing
material.
[0004] Carbon black is known to be characterized by more efficient
near infra-red (NIR) absorption than other IR fillers such as black
iron oxide and graphite. It is critical that the IR filler is
uniformly dispersed in the imaging member surface material. Uniform
dispersion of the filler enables increased absorption efficiency,
which is required for high speed printing. Also, uniform dispersion
of the filler decreases the laser power requirement for adequate
evaporation of dampening fluid of the dampening fluid layer
disposed on the imaging member surface. Furthermore, if the IR
filler is not uniformly distributed in the imaging member surface
material, localized non-uniformity of dampening fluid may results,
negatively affecting image resolution.
SUMMARY
[0005] Conventional carbon black does not uniformly distribute in a
fluorosilicone matrix and creates agglomerates of about one to
about five microns or higher. A uniform dispersion of carbon black
throughout a surface of the imaging plate enables high printing
speed, minimized laser power requirements, and better image
resolution and is desirable. Methods for forming functionalized
carbon black having an amino-terminated fluoropolymer functional
group using a coupling agent. In an embodiment, methods of forming
functionalized carbon black using, for example, amino-terminated
polyfluorodimethylsiloxane are provided that are useful for
printing applications for forming imaging member surface material
having uniformly dispersed carbon black therein.
[0006] Ink-based digital printing systems are discussed by way of
example. Inks in accordance with embodiments may also be suitable
for other printing systems, such as those that include an
intermediate transfer configuration, or toner printing and/or
fusing systems.
[0007] Exemplary embodiments are described herein. It is
envisioned, however, that any system that incorporates features of
systems described herein are encompassed by the scope and spirit of
the exemplary embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows a side diagrammatical view of a related art
ink-based digital printing system;
[0009] FIG. 2 shows a synthesis mechanism for forming a
functionalized carbon black composition in accordance with an
exemplary embodiment;
[0010] FIG. 3 shows a structural formula of a amino-terminated
F-PDMS molecule;
[0011] FIG. 4A shows methods for forming a functionalized carbon
black and a first potential product in accordance with an exemplary
embodiment;
[0012] FIG. 4B shows a second potential product.
DETAILED DESCRIPTION
[0013] Exemplary embodiments are intended to cover all
alternatives, modifications, and equivalents as may be included
within the spirit and scope of methods and systems as described
herein.
[0014] The modifier "about" used in connection with a quantity is
inclusive of the stated value and has the meaning dictated by the
context (for example, it includes at least the degree of error
associated with the measurement of the particular quantity). When
used with a specific value, it should also be considered as
disclosing that value.
[0015] Reference is made to the drawings to accommodate
understanding of systems for ink-based digital printing using a
system having an imaging member for which functionalized carbon
black formed in accordance with methods of embodiments are useful,
and methods of forming functionalized carbon black in accordance
with embodiments. In the drawings, like reference numerals are used
throughout to designate similar or identical elements.
[0016] Ink-based digital printing or variable data lithographic
printing systems are discussed to provide an example of an
advantageous use for functionalized carbon black formed by methods
in accordance with embodiments. Functionalized carbon black
compositions formed by methods of embodiments may be useful for
other printing applications, and are particularly useful for
ink-based digital printing applications because they may be
uniformly dispersed in an imaging member surface layer to enable
high speed, high quality ink-based digital printing. Ink-based
digital printing systems are discussed by way of example. Inks in
accordance with embodiments may also be suitable for other printing
systems, such as those that include an intermediate transfer
configuration, or toner printing and/or fusing systems.
[0017] "Variable data lithography printing," or "ink-based digital
printing," or "digital offset printing" is lithographic printing of
variable image data for producing images on a substrate that are
changeable with each subsequent rendering of an image on the
substrate in an image forming process. "Variable data lithographic
printing" includes offset printing of ink images using lithographic
ink wherein the images are based on digital image data that may
vary from image to image. Ink-based digital printing uses a
variable data lithography printing system, or digital offset
printing system. A "variable data lithography system" is a system
that is configured for lithographic printing using lithographic
inks and based on digital image data, which may be variable from
one image to the next.
[0018] Such systems are disclosed in U.S. patent application Ser.
No. 13/095,714 ("714 application"), titled "Variable Data
Lithography System," filed on Apr. 27, 2011, by Stowe et al., the
disclosure of which is hereby incorporated by reference herein in
its entirety. The systems and methods disclosed in the 714
application are directed to improvements on various aspects of
previously-attempted variable data imaging lithographic marking
concepts based on variable patterning of dampening fluids to
achieve effective truly variable digital data lithographic
printing.
[0019] The 714 application describes an exemplary variable data
lithography system 100 for ink-based digital printing, such as that
shown, for example, in FIG. 1. A general description of the
exemplary system 100 shown in FIG. 1 is provided here. Additional
details regarding individual components and/or subsystems shown in
the exemplary system 100 of FIG. 1 may be found in the 714
application.
[0020] As shown in FIG. 1, the exemplary system 100 may include an
imaging member 110. The imaging member 110 in the embodiment shown
in FIG. 1 is a drum, but this exemplary depiction should not be
interpreted so as to exclude embodiments wherein the imaging member
110 includes a drum, plate or a belt, or another now known or later
developed configuration. The reimageable surface may be formed of
materials including, for example, silicones, including
polydimethylsiloxane (PDMS), FKMs among others. The reimageable
surface may be formed of a relatively thin layer over a mounting
layer, a thickness of the relatively thin layer being selected to
balance printing or marking performance, durability and
manufacturability.
[0021] The imaging member 110 is used to apply an ink image to an
image receiving media substrate 114 at a transfer nip 112. The
transfer nip 112 is formed by an impression roller 118, as part of
an image transfer mechanism 160, exerting pressure in the direction
of the imaging member 110. Image receiving medium substrate 114
should not be considered to be limited to any particular
composition such as, for example, paper, plastic, or composite
sheet film. The exemplary system 100 may be used for producing
images on a wide variety of image receiving media substrates. The
714 application also explains the wide latitude of marking
(printing) materials that may be used, including marking materials
with pigment densities greater than 10% by weight. As does the 714
application, this disclosure will use the term ink to refer to a
broad range of printing or marking materials to include those which
are commonly understood to be inks, pigments, and other materials
which may be applied by the exemplary system 100 to produce an
output image on the image receiving media substrate 114.
[0022] The 714 application depicts and describes details of the
imaging member 110 including the imaging member 110 being comprised
of a reimageable surface layer formed over a structural mounting
layer that may be, for example, a cylindrical core, or one or more
structural layers over a cylindrical core.
[0023] The system 100 includes a dampening fluid system 120
generally comprising a series of rollers, which may be considered
as dampening rollers or a dampening unit, for uniformly wetting the
reimageable surface of the imaging member 110 with dampening fluid.
A purpose of the dampening fluid system 120 is to deliver a layer
of dampening fluid, generally having a uniform and controlled
thickness, to the reimageable surface of the imaging member 110. As
indicated above, it is known that a dampening fluid such as
fountain solution may comprise mainly water optionally with small
amounts of isopropyl alcohol or ethanol added to reduce surface
tension as well as to lower evaporation energy necessary to support
subsequent laser patterning, as will be described in greater detail
below. Small amounts of certain surfactants may be added to the
fountain solution as well. Alternatively, other suitable dampening
fluids may be used to enhance the performance of ink based digital
lithography systems. Exemplary dampening fluids include water,
Novec 7600
(1,1,1,2,3,3-Hexafluoro-4-(1,1,2,3,3,3-hexafluoropropoxyl)pentane
and has CAS#870778-34-0.), and D4 (octamethylcyclotetrasiloxane).
Other suitable dampening fluids are disclosed, by way of example,
in co-pending U.S. patent application Ser. No. 13/284,114, filed on
Oct. 28, 2011, titled DAMPENING FLUID FOR DIGITAL LITHOGRAPHIC
PRINTING, the disclosure of which is hereby incorporated herein by
reference in its entirety.
[0024] Once the dampening fluid is metered onto the reimageable
surface of the imaging member 110, a thickness of the dampening
fluid may be measured using a sensor 125 that may provide feedback
to control the metering of the dampening fluid onto the reimageable
surface of the imaging member 110 by the dampening fluid system
120.
[0025] After a precise and uniform amount of dampening fluid is
provided by the dampening fluid system 120 on the reimageable
surface of the imaging member 110, and optical patterning subsystem
130 may be used to selectively form a latent image in the uniform
dampening fluid layer by image-wise patterning the dampening fluid
layer using, for example, laser energy. Typically, the dampening
fluid will not absorb the optical energy (IR or visible)
efficiently. The reimageable surface of the imaging member 110
should ideally absorb most of the laser energy (visible or
invisible such as IR) emitted from the optical patterning subsystem
130 close to the surface to minimize energy wasted in heating the
dampening fluid and to minimize lateral spreading of heat in order
to maintain a high spatial resolution capability. Alternatively, an
appropriate radiation sensitive component may be added to the
dampening fluid to aid in the absorption of the incident radiant
laser energy. While the optical patterning subsystem 130 is
described above as being a laser emitter, it should be understood
that a variety of different systems may be used to deliver the
optical energy to pattern the dampening fluid.
[0026] The mechanics at work in the patterning process undertaken
by the optical patterning subsystem 130 of the exemplary system 100
are described in detail with reference to the 714 application's
FIG. 5. Briefly, the application of optical patterning energy from
the optical patterning subsystem 130 results in selective removal
of portions of the layer of dampening fluid.
[0027] Following patterning of the dampening fluid layer by the
optical patterning subsystem 130, the patterned layer over the
reimageable surface of the imaging member 110 is presented to an
inker subsystem 140. The inker subsystem 140 is used to apply a
uniform layer of ink over the layer of dampening fluid and the
reimageable surface layer of the imaging member 110. The inker
subsystem 140 may use an anilox roller to meter an offset
lithographic ink onto one or more ink forming rollers that are in
contact with the reimageable surface layer of the imaging member
110. Separately, the inker subsystem 140 may include other
traditional elements such as a series of metering rollers to
provide a precise feed rate of ink to the reimageable surface. The
inker subsystem 140 may deposit the ink to the pockets representing
the imaged portions of the reimageable surface, while ink on the
unformatted portions of the dampening fluid will not adhere to
those portions.
[0028] The cohesiveness and viscosity of the ink residing in the
reimageable layer of the imaging member 110 may be modified by a
number of mechanisms. One such mechanism may involve the use of a
rheology (complex viscoelastic modulus) control subsystem 150. The
rheology control system 150 may form a partial crosslinking core of
the ink on the reimageable surface to, for example, increase ink
cohesive strength relative to the reimageable surface layer. Curing
mechanisms may include optical or photo curing, heat curing,
drying, or various forms of chemical curing. Cooling may be used to
modify rheology as well via multiple physical cooling mechanisms,
as well as via chemical cooling.
[0029] The ink is then transferred from the reimageable surface of
the imaging member 110 to a substrate of image receiving medium 114
using a transfer subsystem 160. The transfer occurs as the
substrate 114 is passed through a nip 112 between the imaging
member 110 and an impression roller 118 such that the ink within
the voids of the reimageable surface of the imaging member 110 is
brought into physical contact with the substrate 114. With the
adhesion of the ink having been modified by the rheology control
system 150, modified adhesion of the ink causes the ink to adhere
to the substrate 114 and to separate from the reimageable surface
of the imaging member 110. Careful control of the temperature and
pressure conditions at the transfer nip 112 may allow transfer
efficiencies for the ink from the reimageable surface of the
imaging member 110 to the substrate 114 to exceed 95%. While it is
possible that some dampening fluid may also wet substrate 114, the
volume of such a dampening fluid will be minimal, and will rapidly
evaporate or be absorbed by the substrate 114.
[0030] In certain offset lithographic systems, it should be
recognized that an offset roller, not shown in FIG. 1, may first
receive the ink image pattern and then transfer the ink image
pattern to a substrate according to a known indirect transfer
method.
[0031] Following the transfer of the majority of the ink to the
substrate 114, any residual ink and/or residual dampening fluid
must be removed from the reimageable surface of the imaging member
110, preferably without scraping or wearing that surface. An air
knife may be employed to remove residual dampening fluid. It is
anticipated, however, that some amount of ink residue may remain.
Removal of such remaining ink residue may be accomplished through
use of some form of cleaning subsystem 170. The 714 application
describes details of such a cleaning subsystem 170 including at
least a first cleaning member such as a sticky or tacky member in
physical contact with the reimageable surface of the imaging member
110, the sticky or tacky member removing residual ink and any
remaining small amounts of surfactant compounds from the dampening
fluid of the reimageable surface of the imaging member 110. The
sticky or tacky member may then be brought into contact with a
smooth roller to which residual ink may be transferred from the
sticky or tacky member, the ink being subsequently stripped from
the smooth roller by, for example, a doctor blade.
[0032] The 714 application details other mechanisms by which
cleaning of the reimageable surface of the imaging member 110 may
be facilitated. Regardless of the cleaning mechanism, however,
cleaning of the residual ink and dampening fluid from the
reimageable surface of the imaging member 110 is essential to
preventing ghosting in the proposed system. Once cleaned, the
reimageable surface of the imaging member 110 is again presented to
the dampening fluid system 120 by which a fresh layer of dampening
fluid is supplied to the reimageable surface of the imaging member
110, and the process is repeated.
[0033] The imaging member reimageable surface may comprise a
polymeric elastomer, such as silicone rubber and/or fluorosilicone
rubber or FKMs such as Viton GF from DuPont or P959 from Solvay
Solexis, for example. The term "silicone" is well understood in the
art and refers to polyorganosiloxanes having a backbone formed from
silicon and oxygen atoms and sidechains containing carbon and
hydrogen atoms. For the purposes of this application, the term
"silicone" should also be understood to exclude siloxanes that
contain fluorine atoms, while the term "fluorosilicone" is used to
cover the class of siloxanes that contain fluorine atoms. Other
atoms may be present in the silicone rubber, for example nitrogen
atoms in amine groups which are used to link siloxane chains
together during crosslinking. The side chains of the
polyorganosiloxane can also be alkyl or aryl.
[0034] A "fluoroelastomer" is a fluorocarbon-derivative, a
synthetic rubber. The term fluoroelastomer is well understood in
the art. A fluoroelastomer or fluoro rubber of the polymethylene
type uses vinylidene fluoride as a comonomer and has substituent
fluoro, alkyl, perfluoroalkyl, or perfuoroalkoxy groups on the
polymer chain. Fluoroelastomers are categorized under the ASTM
D1418, and have the ISO 1629 designation FKM. This class of
elastomer is a family comprising copolymers of hexafluoropropylene
(HFP) and vinyldiene fluoride (VDF or VF2), terpolymers of
tetrafluoroethylene (TFE), vinyldiene fluoride (VDF) and
hexafluoropropylene (HFP) and perfluoromethylvinylether (PMVE)
containing components. Exemplary fluoroelastomers are commercially
available from DuPont Performance Elastomers L.L.C. under the VITON
brand, and from Solay under the TECNOFLON brand as P959.
[0035] The term "alkyl" as used herein refers to a group composed
entirely of carbon atoms and hydrogen atoms that is fully
saturated. The alkyl group may include a chain that is linear,
branched, or cyclic. For example, linear alkyl radicals generally
have the formula .C.sub.nH.sub.2n+1.
[0036] The term "aryl" refers to an aromatic group composed
entirely of carbon atoms and hydrogen atoms. When aryl is described
in connection with a numerical range of carbon atoms, it should not
be construed as including substituted aromatic radicals.
[0037] The term "alkoxy" refers to an alkyl group singular bonded
to an oxygen atom.
[0038] The term "amino" refers to a group containing a nitrogen
atom attached by single bonds to hydrogen atoms, alkyl groups, aryl
groups, or a combination thereof. An "amine" is an organic compound
that contains an amino group. Amines are derivates of the inorganic
compound ammonia.
[0039] Methods in accordance with embodiments include
functionalizing carbon black with amino-terminated fluoropolymers,
e.g., fluorosilicones, to yield a uniform and stable dispersion in
a fluorosilicone matrix or in a FKM matrix. In an embodiment, the
carbon black particles are chemically modified with
amino-functionalized fluorosilicone, such as amino-terminated
F-PDMS ("EF"), or other similar compounds, by the formation of
amide bonds between surface carboxylic groups of CB particles and
amino groups of the EF and a coupling agent such as
N,N'-dicyclohexylcarbodiimide (DCC).
[0040] Amino-functionalized carbon black was produced using methods
in accordance with an embodiment. Carbon black particles, available
as Orion L6 carbon black from Printex L6 carbon black from Orion
Engineered Carbons were oxidized with concentrated nitric acid,
HNO.sub.3, to increase the concentration of carboxylic groups on
the surface of the carbon black particles and cause the surface to
be more reactive. Then, EF was chemically grafted to the carboxylic
groups of the carbon black particles by way of amide bonds. The
functionalization was confirmed by x-ray photoelectron spectroscopy
("XPS").
[0041] The resulting dispersions were very stable in the
trifluorotoluene ("TFT") for days. The optical microscopy showed
that when the functionalized carbon black is added to the
fluorosilicone matrix, very uniform and small particle size
dispersion (at least about 500 nm or less) resulted in comparison
with 1-5 micron aggregates and non-uniform dispersion found in
related art unmodified carbon black particles. This is particularly
important because it enables tailoring electrical and mechanical
properties of filled systems at lower loadings. This enables lower
power lasers, higher printing speed and better image resolution for
ink-based digital printing systems such as those shown in FIG. 1,
for example.
[0042] FIG. 2 shows methods for forming functionalized carbon black
in accordance with an exemplary embodiment. A product of carbon
black functionalization in accordance with methods of embodiments
may include a carbon black molecule having a functional group
selected from at least of an acid moiety, and/or may include
addition of alcohol, ketone, and quinone groups. Functionalized
carbon black samples formed in accordance with methods were
characterized using XPS, and the data is presented Table 1. The
data shown in Table 1 indicates presence of nitrogen and fluorine
in EF modified carbon black, which indicates the functionalization
of carbon black with EF by way of the amide bond.
TABLE-US-00001 TABLE 1 XPS Data C N O F Si S (at %) (at %) (at %)
(at %) (at %) (at %) Carbon Black I 98.53 0.00 1.31 0.00 0.00 0.16
Carbon Black 96.14 0.00 3.72 0.00 0.00 0.14 HNO3 II Carbon Black
83.14 3.04 7.67 3.57 2.53 0.06 EF III
[0043] As shown in FIG. 2, methods may include mixing carbon black
with concentrated nitric acid at S2001. Nitric acid may be mixed
with carbon black for seven hours at room temperature to oxidize
the carbon black and increase an amount carboxylic acid groups on a
surface of the carbon black particle. The oxidized carbon black may
be repeatedly washed in deionized water using an ultracentrifuge
until a pH of the carbon black solution is around 5. The carbon
black may be dried using a vacuum at 150 degrees Celsius for one
hour.
[0044] Then, EF is added to the functionalized carbon black
molecule with DCC in the presence of trifluorotoulene ("TFT") at
S2002 whereby EF is chemically grafted to the carboxylic group(s)
of the carbon black particle to form carbon black having an
amino-functionalized fluorosilicone functional group. In
particular, oxidized carbon black may be added to TFT, followed by
addition of EF and DCC. The resulting mixture may be stirred
overnight, and subsequently washed with TFT and processed using an
ultracentrifuge to remove residual EF and DCC. TFT byproducts may
be evaporated using a vacuum oven. The product functionalized
carbon black may be redispersed in TFT, for example. The
functionalized carbon black samples that were tested to produce the
data shown in Table 1 were formed using 0.726 g of carbon black, 10
g of TFT, and 1 g of DCC.
[0045] Exemplary EF compounds may include aminoterminated
fluorinated polydimethylsiloxane (PDMS). PDMS or dimethicone is a
mineral-organic polymer (a structure containing carbon, silicon and
oxygen) of the siloxane family that is readily available. The
chemical formula for PDMS is
CH.sub.3[Si(CH.sub.3).sub.2O].sub.nSi(CH.sub.3).sub.3, where n is
the number of repeating monomer SiO(CH.sub.3).sub.2] units.
Alternatively, other exemplary fluoropolymers including
poly(vinylmethyl)siloxane (PVMS) may comprise the aminoterminated
fluoropolymer that may be used to form aminofunctionalized carbon
black in accordance with provided methods.
[0046] FIG. 3 shows a chemical structure of amino-terminated
F-PDMS, which may comprise the EF component used in methods of
embodiments. Amino-terminated F-PDMS having the structure shown in
FIG. 3 is known and readily available from, for example, Wacker
Chemie AG.
[0047] Methods for forming functionalized carbon black in
accordance with embodiments may work in accordance with the
reaction mechanism shown in FIG. 4A. In particular, FIG. 4A shows a
possible reaction mechanism of functionalization of carbon black.
In particular, FIG. 4A shows oxidized carbon black being combined
with DCC at S4005. The product molecule is caused to react with an
EF molecule at S4007, yielding DCHU as a byproduct, and
amino-terminated functionalized carbon black. The functionalized
carbon black product shown in FIG. 4A includes a surface being
bonded by a single amino group of the EF by way of an amide
bond.
[0048] The product shown in FIG. 4A is believed to be an
energetically favorable product because the reaction pathway yields
excess EF. A second potential product is shown in FIG. 4B. The
second potential product includes a surface of carbon black bonded
by two amino groups of an EF molecule by way of amide bonds.
[0049] The modified carbon black prepared for producing the results
shown in Table 1 were further dispersed in fluorosilicone and an
optical microscopy was carried out to check a quality of dispersion
in unmodified carbon black and EF-modified carbon black. An optical
micrograph showing unmodified carbon black dispersed in
fluorosilicone was compared with a micrograph of EF-functionalized
carbon black in fluorosilicone. The results showed that unmodified
carbon black, which tended to agglomerate with 1-5 micron or higher
aggregates, did not uniformly disperse in the solution. Contrarily,
EF functonalized carbon black was uniformly distributed, and no
aggregates were observed using an optical microscope. As such, a
size of agglomerates was found to be less than 500 nanometers.
[0050] It will be appreciated that the above-disclosed and other
features and functions, or alternatives thereof, may be desirably
combined into many other different systems or applications. Also,
various presently unforeseen or unanticipated alternatives,
modifications, variations or improvements therein may be
subsequently made by those skilled in the art.
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