U.S. patent application number 14/275675 was filed with the patent office on 2015-04-09 for high performance silicon-based compositions.
This patent application is currently assigned to BURNING BUSH TECHNOLOGIES, LLC. The applicant listed for this patent is BURNING BUSH GROUP, LLC. Invention is credited to Chris Fish.
Application Number | 20150099848 14/275675 |
Document ID | / |
Family ID | 52777163 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150099848 |
Kind Code |
A1 |
Fish; Chris |
April 9, 2015 |
HIGH PERFORMANCE SILICON-BASED COMPOSITIONS
Abstract
Provided herein are silicon-based compositions, which after
curing is a coating composition having strong substrate adhesion
and scratch resistance. The compositions are formed from a mixture
of constituents comprising: from about 20% to about 90% (w/w) of a
first siloxane selected from the group consisting of
silsesquioxane, methylmethoxysiloxane, and combinations thereof;
and from about 10% to about 80% (w/w) of one or more silicon
compounds selected from the group consisting of a second siloxane,
silane, and silazane. Optionally, the compositions may comprise
from about 0.1% to about 5% (w/w) alkyltitanate.
Inventors: |
Fish; Chris; (Central Point,
OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BURNING BUSH GROUP, LLC |
Kansas City |
MO |
US |
|
|
Assignee: |
BURNING BUSH TECHNOLOGIES,
LLC
Kansas City
MO
|
Family ID: |
52777163 |
Appl. No.: |
14/275675 |
Filed: |
May 12, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61886841 |
Oct 4, 2013 |
|
|
|
Current U.S.
Class: |
524/588 ;
427/387; 528/37 |
Current CPC
Class: |
B29C 70/34 20130101;
Y10T 156/1044 20150115; B29C 70/462 20130101; Y10T 428/1372
20150115; C09D 183/16 20130101; B29K 2105/124 20130101; C08K 3/04
20130101; C08K 2003/385 20130101; C08L 83/00 20130101; C08L 83/00
20130101; C08K 3/04 20130101; C08K 3/04 20130101; C08K 3/38
20130101; C08K 3/04 20130101; C08K 3/38 20130101; C08L 83/00
20130101; C08K 3/04 20130101; C08L 83/00 20130101; C08K 3/38
20130101; C08L 83/00 20130101; C08L 83/16 20130101; C08L 83/04
20130101; Y10T 442/2984 20150401; C09D 183/04 20130101; C08L 83/04
20130101; C09D 183/16 20130101; C08G 77/62 20130101; B29K 2083/00
20130101; Y10T 428/25 20150115; C08K 3/38 20130101; Y10T 442/20
20150401; C08L 83/16 20130101; C09D 183/04 20130101; C08K 3/38
20130101 |
Class at
Publication: |
524/588 ;
427/387; 528/37 |
International
Class: |
C09D 183/04 20060101
C09D183/04; C09D 183/08 20060101 C09D183/08; B05D 3/02 20060101
B05D003/02 |
Claims
1. (canceled)
2. (canceled)
3. A silicon-based composition, which after curing is a coating
composition having strong substrate adhesion, scratch resistance,
and solvent resistance, the composition formed from a mixture of
constituents comprising: from about 20% to about 90% (w/w, of the
total composition) of a first siloxane consisting of
methylsilsesquioxane and an .alpha., .omega. methoxy-terminated
polydimethylsiloxane, wherein the .alpha., .omega.
methoxy-terminated polydimethylsiloxane is at least 10% (w/w, of
the total composition); and from about 10% to about 80% (w/w, of
the total composition) of one or more silicon compounds selected
from the group consisting of a second siloxane, silane, and
silazane.
4. The composition of claim 1, wherein the first siloxane consists
of from about 10% to about 70% (w/w, of the total composition)
methylsilsesquioxane and from about 10% to about 50% (w/w, of the
total composition) .alpha., .omega. methoxy-terminated
polydimethylsiloxane.
5. The composition of claim 3, further comprising from about 0.1%
to about 5% (w/w, of the total composition) alkyltitanate.
6. The composition of claim 5, wherein the alkyltitanate comprises
butyltitanate present in an amount ranging from about 0.5% to about
2% (w/w, of the total composition).
7. The composition of claim 5, comprising one or more silicon
compounds from about 10% to about 50% (w/w, of the total
composition).
8. The composition of claim 5, comprising silane selected from the
group consisting of trimethoxysilane, triethoxysilane,
aminopropylsilane, and polysilane.
9. The composition of claim 5, wherein the one or more silicon
compounds comprises methylphenylsilicone resin.
10. The composition of claim 3, wherein the silicon compound
comprises a combination of from about 10% to about 50% (w/w, of the
total composition) triethoxysilane, and from about 10% to about 20%
(w/w, of the total composition) methylphenylsilicone resin; and an
alkyltitanate comprising from about 0.5% to about 2% (w/w, of the
total composition) butyltitanate.
11. A polymer formed from the polymerization of a mixture
comprising a first siloxane consisting of methylsilsesquioxane and
polydimethylsiloxane; and one or more silicon compounds selected
from the group consisting of a second siloxane, silane, and
silazane; the polymer comprising: a siloxane ladder structure
comprising a repeating unit of formula (I), ##STR00021## wherein
each R.sup.1 is hydrocarbyl, and wherein n is between 4 and
100.
12. The polymer of claim 11, wherein R.sup.1 is alkyl.
13. The polymer of claim 11, wherein R.sup.1 is methyl.
14. A compound comprising formula (II), ##STR00022## wherein: each
R.sup.1 is hydrocarbyl; each R.sup.2 is alkyl; each A is selected
from the group consisting of ##STR00023## each R.sup.3 is selected
from the group consisting of alkyl and SiH(OR.sup.4).sub.2; each
R.sup.4 is selected from the group consisting of methyl and ethyl;
n is between 4 and 100; and x, y, and z are each between 1 and
100.
15. The compound of claim 14, wherein each R.sup.1 is methyl.
16. The compound of claim 14, wherein each R.sup.2 is butyl.
17. The compound of claim 14, wherein x, y, and z are each between
5 and 25.
18. The compound of claim 14, wherein the compound of formula (II)
comprises a compound of formula (III): ##STR00024##
19. A method of coating a surface, which method comprises: (a)
mixing silicon-based constituents to form a silicon-based coating
composition comprising: from about 20% to about 90% (w/w, of the
total composition) of a first siloxane consisting of
methylsilsesquioxane, and .alpha., .omega. methoxy-terminated
polydimethylsiloxane wherein the .alpha., .omega.
methoxy-terminated polydimethylsiloxane is at least 10% (w/w, of
the total composition); and from about 10% to about 80% (w/w, of
the total composition) of one or more silicon compounds selected
from the group consisting of a second siloxane, silane, and
silazane; (b) coating the mixture onto a surface; and (c) curing
the coating at a temperature from about 20.degree. C. to about
400.degree. C. for about 0.3 hours to about 5 hours.
20. The method of claim 19, wherein the first siloxane consists of
from about 10% to about 70% (w/w, of the total composition)
methylsilsesquioxane and from about 10% to about 50% (w/w, of the
total composition) .alpha., .omega. methoxy-terminated
polydimethylsiloxane; and wherein, the silicon compound comprises a
combination of from about 10% to about 50% (w/w, of the total
composition) triethoxysilane, and from about 10% to about 20% (w/w,
of the total composition) methylphenylsilicone resin.
21. The method of claim 19, wherein the silicon-based coating
composition further comprises from about 0.1% to about 5% (w/w, of
the total composition) alkyltitanate.
22. The method of claim 21, wherein the alkyltitanate comprises
from about 0.5% to about 2% (w/w, of the total composition)
butyltitanate.
23.-25. (canceled)
26. The method of claim 19, wherein the coating is cured at a
temperature of about 300.degree. C. to about 400.degree. C. for
about 0.3 hours to about 5 hours to form the coating
composition.
27.-32. (canceled)
Description
CROSS-REFERENCE
[0001] This disclosure claims benefit of the filing date under 35
U.S.C. .sctn.119 to U.S. Provisional Patent Application Ser. No.
61/886,841 filed Oct. 4, 2013, and entitled "High Performance
Silicon-Based Compositions," which is herein incorporated by
reference in its entirety for all purposes.
TECHNICAL FIELD
[0002] The present disclosure relates to silicon-based compositions
formed from a mixture of silsesquioxane, methoxymethylsiloxane, at
least one of a second siloxane, silazane, or silane, and optionally
an alkyltitanate. The resultant composition may be used to form
coatings having resistance to oxidization and photodegradation.
BACKGROUND
[0003] Coatings are used in a wide variety of contexts to modify
the surface properties of a bulk material. For example, it is
beneficial for the surfaces of medical devices to resist
degradation upon contact with body fluids, both to maintain the
integrity of the medical device itself and to protect the patient
from potentially harmful degradants and leachates originating from
the coating. Coating stability is also promoted when the coating
resists photodegradation, bleaching, and atmospheric oxidation. The
coating should strongly adhere to its substrate, being resistant to
mechanical wear and thermal stress. In some contexts, optical
clarity of a cured coating is valuable, especially when the
substrate itself is transparent.
SUMMARY
[0004] The silicon-based compositions described herein provide
hard, heat resistant, and chemical resistant coatings that strongly
bond to their substrates. These coatings resist photodegradation in
visible and ultraviolet light, and resist oxidation under ambient
conditions. The coatings can harden in less than a day, and, in
some contexts, in less than an hour. The compositions may be used
as single-component systems, resulting in a reduced unit cost
compared to two-component systems. The compositions may also be
cured either under ambient conditions or at an elevated
temperature, without added solvent.
[0005] In particular, one aspect of the present disclosure provides
a silicon-based composition, which after curing is a coating
composition having strong substrate adhesion and scratch
resistance. The composition is formed from a mixture of
constituents comprising from about 20% to about 90% (w/w) of a
first siloxane selected from the group consisting of
silsesquioxane, methylmethoxysiloxane, and combinations thereof;
and from about 10% to about 80% (w/w) of one or more silicon
compounds selected from the group consisting of a second siloxane,
silane, and silazane. Upon curing, the silicon-based compounds
provide coatings that are strong, resist mechanical damage, resist
chemical attack, resist UV irradiation, and are stable against
oxidation.
[0006] The composition may comprise from about 45% to about 90%
(w/w) of a first siloxane. The silsesquioxane may be
methylsilsesquioxane. The first siloxane may comprise a combination
of from about 10% to about 70% (w/w) methylsilsesquioxane and from
about 10% to about 50% (w/w) methylmethoxysiloxane. The composition
may further comprise from about 0.1% to about 5% (w/w)
alkyltitanate. The alkyltitanate may comprise butyltitanate present
in an amount ranging from about 2% to about 5% (w/w). The one or
more silicon compounds may comprise from about 10% to about 50%
(w/w) of the total composition. The silane may be selected from the
group consisting of trimethoxysilane, triethoxysilane,
aminopropylsilane, aminopropylmethyldioxysilane, and polysilane. In
a particular embodiment, the first siloxane may comprise a
combination of from about 10% to about 70% (w/w)
methylsilsesquioxane and from about 10% to about 50% (w/w)
methylmethoxysiloxane; the silicon compound may comprise a
combination from about 10% to about 50% (w/w) triethoxysilane, and
from about 10% to about 20% (w/w) methylphenylsilicone resin; and
an alkyltitanate may comprise from about 0.5% to about 2% (w/w)
butyltitanate.
[0007] Another aspect of this disclosure provides a polymer formed
from the polymerization of a mixture comprising a first siloxane
comprising silsesquioxane and methoxymethylsiloxane; and one or
more silicon compounds selected from the group consisting of a
second siloxane, silane, and silazane. The polymer comprises a
siloxane ladder structure comprising a repeating unit of formula
(I),
##STR00001##
[0008] wherein each R.sup.1 is hydrocarbyl, and wherein n is
between 4 and 100. In particular, R.sup.1 may be alkyl, such as
methyl. These polymers are strong, resist mechanical damage, resist
chemical attack, resist UV irradiation, and are stable against
oxidation.
[0009] A further aspect of this disclosure provides a compound
comprising formula (II),
##STR00002##
[0010] wherein:
[0011] each R.sup.1 is hydrocarbyl;
[0012] each R.sup.2 is alkyl;
[0013] each A is selected from the group consisting of
##STR00003##
[0014] each R.sup.3 is selected from the group consisting of alkyl
and SiH(OR.sup.4).sub.2;
[0015] each R.sup.4 is selected from the group consisting of methyl
and ethyl;
[0016] n is between 4 and 100; and
[0017] x, y, and z are each between 1 and 100.
[0018] Each R.sup.1 may be methyl. Each R.sup.2 my be butyl. The
numbers x, y, and z may each between 5 and 25.
[0019] In a particular embodiment of this aspect, the compound of
formula (II) may comprise a compound of formula (III):
##STR00004##
[0020] A still further aspect of this disclosure provides a method
of coating a surface. A mixture of constituents is mixed to form a
silicon-based coating composition comprising from about 20% to
about 90% (w/w) of a first siloxane selected from the group
consisting of silsesquioxane, methylmethoxysiloxane, and
combinations thereof; and from about 10% to about 80% (w/w) of one
or more silicon compounds selected from the group consisting of a
second siloxane, silane, and silazane. This mixture is coated onto
a surface. The coating is cured at a temperature from about
20.degree. C. to about 400.degree. C. for about 0.3 hours to about
5 days. The first siloxane may comprise a combination of from about
10% to about 70% (w/w) methylsilsesquioxane and from about 10% to
about 50% (w/w) methylmethoxysiloxane; and the silicon compound may
comprise a combination from about 10% to about 50% (w/w)
triethoxysilane, and from about 10% to about 20% (w/w)
methylphenylsilicone resin. The mixture may further comprise from
about 0.1% to about 5% alkyltitanate. In some embodiments, the
alkyltitanate may comprise from about 2% to about 5% (w/w)
butyltitanate. In some instances, the coating may be cured at a
temperature of about 20.degree. C. to about 30.degree. C. for about
1 day to about 5 days to form the coating composition. In other
instances, the coating may be cured at a temperature of about
60.degree. C. to about 70.degree. C. for about 2 hours to about 24
hours to form the coating composition. In yet other instances, the
coating may be cured at a temperature of about 125.degree. C. to
about 150.degree. C. for about 1 hours to about 2 hours to form the
coating composition. In still other instances, the coating may be
cured at a temperature of about 300.degree. C. to about 400.degree.
C. for about 0.3 hours to about 5 hours to form the coating
composition.
[0021] Additional embodiments and features are set forth in part in
the description that follows, and in part will become apparent to
those skilled in the art upon examination of the specification, or
may be learned by the practice of the embodiments discussed herein.
A further understanding of the nature and advantages of certain
embodiments may be realized by reference to the remaining portions
of the specification and the drawings, which forms a part of this
disclosure.
BRIEF DESCRIPTION OF THE FIGURES
[0022] In addition to the exemplary aspects and embodiments
described above, further aspects and embodiments will become
apparent by reference to the drawings and by study of the following
descriptions.
[0023] FIG. 1 depicts the Fourier transform infrared (FTIR)
spectrum for Silres.RTM. MSE-100 from Wacker Chemical
Corporation.
[0024] FIG. 2 depicts the FTIR spectrum for the Tyzor.TM. BTP
polymeric butyltitanate.
[0025] FIG. 3 depicts the FTIR spectrum for the polymerization of a
Silres.RTM. siloxane enhanced by Tyzor.TM. BTP from Dorf Kettle
Specialty Catalysts, LLC.
[0026] FIG. 4 depicts a reaction mechanism of the polymerization of
a Silres.RTM. siloxane enhanced by Tyzor.TM. BTP.
[0027] FIG. 5 depicts a compound resulting from the reaction of
Tyzor.TM. BTP with a Silres.RTM. siloxane.
[0028] FIG. 6 depicts the FTIR spectrum for
N-[3-(trimethoxysilyl)propyl]ethylenediamine after reaction with a
compound resulting from the reaction of Tyzor.TM. BTP with a
Silres.RTM. (depicted in FIG. 5).
[0029] FIGS. 7-9 depicts reactions between the compound resulting
from the reaction of Tyzor.TM. BTP with a Silres.RTM. siloxane (as
depicted in FIG. 4) and
N-[3-(trimethoxysilyl)propyl]ethylenediamine.
[0030] FIG. 10 depicts an FTIR spectrum of methylsilsesquioxane
after reaction with polymeric butyltitanate.
[0031] FIG. 11 depicts a reaction sequence for the reaction of
methylsilsesquioxane after reaction with polymeric butyltitantate.
Spheres indicate other portions of the molecule not explicitly
drawn.
[0032] FIG. 12 depicts the FTIR spectrum of a mixture comprising
methylsilsesquioxane, DT-6020, and polymeric butyltitanate.
[0033] FIG. 13 depicts the reaction of methylsilsesquioxane,
N-[3-(trimethoxysilyl)propyl]ethylenediamine, and polymeric
butyltitanate. Notably, ladder structures are not predominantly
formed from this reaction.
[0034] FIG. 14 depicts the FTIR spectrum for KDT HTA.RTM. 1500
resin, as provided by the manufacturer.
[0035] FIG. 15 depicts the FTIR spectrum of a clear coating formed
by reaction of methylsilsesquioxane, methoxymethylsiloxane,
triethoxysilane, and polymeric butyltitanate. The spectrum
indicates the presence of Si--H bonds.
[0036] FIG. 16 depicts a reaction scheme of methylsilsesquioxane,
methoxymethylsiloxane, triethoxysilane, and polymeric
butyltitanate, which resulted in the clear coating.
[0037] FIG. 17 depicts the FTIR spectrum of a compound formed by
reaction of methylsilsesquioxane, a methylphenylsilicone resin, and
polymeric butyltitanate.
[0038] FIG. 18 depicts the formation of oligosiloxane ladders via
the controlled ring-opening of methylsilsesquioxanes, enhanced by
polymeric butyltitanate in the presence of a methylphenylsilicone
resin (Wacker Silres.TM. SY 409).
DETAILED DESCRIPTION
[0039] The present disclosure may be understood by reference to the
following detailed description, taken in conjunction with the
drawings as described above. It is noted that, for purposes of
illustrative clarity, certain elements in various drawings may not
be drawn to scale, may be represented schematically or
conceptually, or otherwise may not correspond exactly to certain
physical configurations of embodiments.
[0040] The present disclosure relates to silicon-based compositions
that provide hard, heat resistant, and chemical resistant coatings
that strongly bond to their substrates. These coatings, and cure
quickly under ambient conditions or at an elevated temperature,
without added solvent.
(I) Silicon-Based Compositions
[0041] The silicon-based compositions comprise a first siloxane
selected from silsesquioxane and methylmethoxysiloxane, and one or
more silicon compounds selected from the group consisting of a
second siloxane, silane, and silazane. Optionally, the compositions
may further comprise an alkytitanate, such as butyltitanate. The
compositions may also further comprise one or more organic or
inorganic substituents, non-reactive solvents, and/or one or more
additives for curing or for finishing, each of which is
proportioned to achieve certain properties.
(a) Siloxane
[0042] The silicon-based compositions of the present disclosure
include at least one siloxane. A "siloxane" is a chemical compound
having branched or unbranched backbones consisting of alternating
silicon and oxygen atoms --Si--O--Si--O-- with side chains R
attached to the silicon atoms (R.sub.1R.sub.2SiO), where R is a
hydrogen atom or a hydrocarbon group. Polymerized siloxanes,
including oligomeric and polymeric siloxane units, with organic
side chains (R.noteq.H) are commonly known as polysiloxanes, or
[SiOR.sub.1R.sub.1].sub.2, wherein n is greater than 1. The
chemical structure for a linear polysiloxane is shown below:
##STR00005##
[0043] In addition to hydrogen, R.sub.1 and R.sub.2 of the
polysiloxane may be independently selected from the group
consisting of alkyl, alkenyl, cycloalkyl, alkylamino, aryl,
aralkyl, and alkylsilyl. Thus, R.sub.1 and R.sub.2 may be, for
example, methyl, ethyl, propyl, butyl, octyl, decyl, vinyl, allyl,
butenyl, octenyl, decenyl, tetradecyl, hexadecyl, eicosyl,
tetracosyl, cyclohexyl, methylcyclohexyl, methylamino, ethylamino,
phenyl, tolyl, xylyl, naphthyl, benzyl, methylsilyl, ethylsilyl,
propylsilyl, butylsilyl, octylsilyl, or decylsilyl. These alkyl,
alkenyl, cycloalky, aryl, alkyl amino, aralkyl and alkylsilyl
groups may each optionally be substituted by one or more
substituents which contain heteroatoms, such as halides, like
chlorine, bromine and iodine; alkoxy groups, such as ethoxy; or
acyl groups, such as acetyl and propionyl. Organic side groups can
be used to link two or more of these --Si--O-- backbones together.
By varying the --Si--O-- chain lengths, side groups, and
crosslinking, polysiloxanes can vary in consistency from liquid to
gel to rubber to hard plastic. Representative examples of
polysiloxane are [SiO(CH.sub.3).sub.2]. (polydimethylsiloxane,
PDMS), [SiO(C.sub.6H.sub.5).sub.2].sub.n (polydiphenylsiloxane),
and polyphenylmethylsiloxane
(CH.sub.3SiO.sub.1.5).sub.x(C.sub.6H.sub.5SiO.sub.1.5).sub.y. In
some embodiments, the silicon-based composition comprises a
polydimethylsiloxane. The chemical structure for
polydimethylsiloxane is shown below:
##STR00006##
[0044] In some embodiments, the siloxane may be
octamethyltrisiloxane,
[(CH.sub.3).sub.3SiO].sub.2Si(CH.sub.3).sub.2, a linear siloxane in
the polydimethylsiloxane family with the INCI name of trisiloxane.
The chemical structure for octamethyltrisiloxane is shown
below:
##STR00007##
[0045] In other embodiments, the siloxane may be a
methoxymethylsiloxane, such as Silres.RTM. MSE-100 (Wacker Chemical
Corporation), consisting of 1 to 10 repeating dimethylsiloxane
units. The FTIR spectrum for Silres.RTM. MSE-100 at FIG. 1
indicates low concentrations (<2 ppm) of residual toluene and
methanol in the bulk material. The chemical structure for
Silres.RTM. MSE-100 is shown below:
##STR00008##
[0046] In still other embodiments, the siloxane may be Silres.RTM.
MK (Wacker Chemical Corporation), consisting of 10 to 100 repeating
dimethylsiloxane units. The chemical structure for Silres.RTM. MK
is shown below:
##STR00009##
[0047] Other methylated siloxanes include, but are not limited to,
Dow 3074 intermediate methylsiloxane, hexamethyldisiloxane,
cyclotetrasiloxane, octamethylcyclotetra-siloxane,
decamethyltetrasiloxane, and decamethylcyclopentasiloxane. The
method of producing high molecular weight polysiloxane product was
disclosed in U.S. App. Pub. 2009/0253884, which is incorporated
herein by reference. In addition, polysiloxane is also commercially
available. As one example, polysiloxane, specifically,
polydimethylsiloxane, may be supplied in isopropyl acetate solvent
by Genesee Polymers Corp. (Burton, Mich.), dimethyl silicone fluids
G-10. In some exemplary embodiments, the siloxane may be
Techneglas.TM. GR-908F produced by Techneglas, LLC, Perrysburg,
Ohio USA and consisting of 98-99 wt. % polyphenylmethylsiloxane
((CH.sub.3SiO.sub.1.5).sub.x(C.sub.6H.sub.5SiO.sub.1.5).sub.y, CAS
Reg. No. 67763-03-5) in 1-2 wt. % ethanol. In other embodiments,
the siloxane Wacker Silres.TM. SY 409, a methylphenylsilicone
resin, as shown below:
##STR00010##
where x and y may each be between 5 and 25.
[0048] In other embodiments, the siloxane may comprise
silsesquioxane, methylmethoxysiloxane, or combinations thereof.
Silsesquioxanes are caged organosilicon compounds with the
empirical formula of RSiO.sub.3/2, wherein R is a hydrocarbyl. In
various embodiments, the R is an alkyl, such as methyl. Typically,
cages of 6-14 silicon atoms and 9-21 oxygen atoms may coexist. A
non-limiting example of methylsilsesquioxane a cage formed by eight
silicon atoms and twelve oxygen atoms, as shown below:
##STR00011##
Once reacted, silsesquioxanes form a tightly interwoven and highly
polymeric network. Silsequioxane and the networks they form are
generally not soluble in water. The final material may be
substantially free of solvents and non-toxic. These final materials
are especially well-suited from medical applications where the
presence of unwanted solvents and toxic agents could be harmful to
the patient.
[0049] The polysiloxane may be used as provided by the
manufacturer. Generally, the amount of polysiloxane used in the
silicon-based compositions is from about 15% and about 90% (w/w) of
the total formula weight of silicon-based composition. In some
embodiments, polysiloxane may comprise about 15%, 16%, 17%, 18%,
19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%,
32%, 33%, 34%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%,
85%, or 90% (w/w), or any range thereof, of the silicon-based
composition. For example, the amount of polysiloxane present in the
silicon-based composition may range from about 15% to about 20%,
from about 20% to about 25%, from about 25% to about 30%, from
about 30% to about 35%, from about 35% to about 40%, from about 40%
to about 45%, from about 45% to about 50%, from about 50% to about
55%, from about 55% to about 60%, from about 60% to about 65%, from
about 65% to about 70%, from about 70% to about 75%, from about 75%
to about 80%, from about 80% to about 85%, or from about 85% to
about 90% (w/w) of the total composition. In some embodiments, the
polysiloxane may comprise less than 90% (w/w) of the total
composition. In other embodiments, the polysiloxane may comprise
less than 80% (w/w) of the total composition. In some other
embodiments, the polysiloxane may comprise less than 60% (w/w) of
the total composition. In still other embodiments, the polysiloxane
may comprise more than 20% (w/w) of the total composition. In yet
other embodiments, the polysiloxane may comprise more than 60%
(w/w) of the total composition. In still yet other embodiments, the
polysiloxane may comprise more than 80% (w/w) of the total
composition.
[0050] Generally, the amount of silsesquioxane used in the
silicon-based compositions is from about 10% and about 70% (w/w) of
the total formula weight of silicon-based composition. In some
embodiments, the silsesquioxane may comprise about 10%, 15%, 20%,
21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%,
34%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% (w/w), or any range
thereof, of the silicon-based composition. For example, the amount
of silsesquioxane present in the silicon-based composition may
range from about 10% to about 15%, from about 15% to about 20%,
from about 20% to about 25%, from about 25% to about 30%, from
about 30% to about 35%, from about 35% to about 40%, from about 40%
to about 45%, from about 45% to about 50%, from about 50% to about
55%, from about 55% to about 60%, from about 60% to about 65%, or
from about 65% to about 70% (w/w) of the total composition. In some
embodiments, the silsesquioxane may comprise less than 70% (w/w) of
the total composition. In other embodiments, the silsesquioxane may
comprise less than 30% (w/w) of the total composition. In still
other embodiments, the silsesquioxane may comprise more than 10%
(w/w) of the total composition. In yet other embodiments, the
silsesquioxane may comprise more than 30% (w/w) of the total
composition.
[0051] Generally, the amount of methylmethoxysiloxane used in the
silicon-based compositions is from about 10% and about 50% (w/w) of
the total formula weight of silicon-based composition. In some
embodiments, the methylmethoxysiloxane may comprise about 10%, 15%,
20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%,
33%, 34%, 35%, 40%, 45%, or 50% (w/w), or any range thereof, of the
silicon-based composition. For example, the amount of
methylmethoxysiloxane present in the silicon-based composition may
range from about 10% to about 15%, from about 15% to about 20%,
from about 20% to about 25%, from about 25% to about 30%, from
about 30% to about 35%, from about 35% to about 40%, from about 40%
to about 45%, or from about 45% to about 50% (w/w) of the total
composition. In some embodiments, the methylmethoxysiloxane may
comprise less than 50% (w/w) of the total composition. In other
embodiments, the methylmethoxysiloxane may comprise less than 20%
(w/w) of the total composition. In still other embodiments, the
methylmethoxysiloxane may comprise more than 10% (w/w) of the total
composition. In yet other embodiments, the methylmethoxysiloxane
may comprise more than 20% (w/w) of the total composition.
(b) Silazane
[0052] The silicon-based compositions of the present disclosure,
prior to curing, may include a silazane constituent. "Silazane" and
"polysilazane," as appearing in the specification and claims are
generic terms intended to include compounds, which contain one or
more silicon-nitrogen bonds in which the nitrogen atom is bonded to
at least two silicon atoms, and may or may not contain cyclic
units. Therefore, the terms "polysilazane" and "silazane polymer"
include monomers, oligomers, cyclic, polycyclic, linear polymers or
resinous polymers having at least one Si--N group in the compound,
or having repeating units of H.sub.2Si--NH; that is,
[H.sub.2Si--NH].sub.n, with "n" greater than 1. The chemical
structure for polysilazane is shown below:
##STR00012##
[0053] An example of silazane oligomer is disilazane
H.sub.3Si--NH--SiH.sub.3. The oligomeric or polymeric silazanes may
be amorphous or crystalline. Silazane polymer chains having both
large chains and small rings with a wide range of molecular mass
are called "polysilazanes." Exemplary polysilazane or a mixture of
polysilazanes include, but are not limited to, silazanes,
disilazanes, polysilazanes, ureasilazanes, polyureasilazanes,
aminosilanes, organosilazanes, organopolysilazanes, inorganic
polysilazanes, and others employing liquid anhydrous ammonia in
their production. A polysilazane with the general formula
(CH.sub.3).sub.3Si--NH--[(CH.sub.3).sub.2Si--NH].sub.n--Si(CH.sub-
.3).sub.3 is designated as polydimethylsilazane. One group of
polysilazane, [R.sub.1R.sub.2Si--NH].sub.n, is isoelectronic with
and close relatives to polysiloxane [R.sub.1R.sub.2Si--O].sub.n.
Additionally, Si--N bond can be found in triethylsilylamine
((H.sub.5C.sub.2).sub.3Si--NH.sub.2), which is a typical
aminosilane. Further, small ring-shaped molecules with a basic
group of Si--N are called "cyclosilazanes." For example,
triazatrisilane (H.sub.9N.sub.3Si.sub.3) is a typical
cyclotrisilazane.
[0054] A silazane constituent is commonly produced by ammonolysis
of a halosilane, such as a chlorosilane or an organochlorosilane.
In this process, the nitrogen nucleophilically attacks the carbon
alpha to the chlorine, forming a new Si--N bond and releasing
hydrochloric acid (HCl) as a byproduct. The HCl then reacts with
excess ammonia in the reaction mixture, producing ammonium
chloride. Because of the ammonolysis process, the silicon and
nitrogen atoms have a preferable distribution within the cured
resin.
[0055] If the silazane is not properly isolated after synthesis,
the silazane constituent may contain residual ammonia reactant,
free amine from side reactions, and ammonium chloride byproduct.
These nitrogen-containing materials are undesirable at least
because of their environmental toxicity. Also, the first- and
second-order elimination reactions may lead to alkyl and vinyl
substituents, producing, for example, chloromethylvinylsilane,
chlorodivinylsilane, dichloroethylvinylsilane,
chloromethyldivinylsilane, etc., depending on the
organochlorosilane starting material. Before curing, the vinyl
groups in particular can react with low molecular weight compounds
and facilitate polymerization. These polymerization reactions
increase the chain length and the degree of three-dimensional
crosslinking of the polymer networks in the cured coatings. As a
result, they may have much higher mass ranges and significantly
improved material properties.
[0056] For polymerized silicon-based compositions, ammonia may be
used to dissolve and age the materials, which must be carefully
regulated through venting to control the molecular weight of the
resin starting material. This reaction results in a
R.sub.3Si--NH.sub.2 group to form silazane units by releasing
ammonia. High moisture and/or water cause decomposition of the
polymerized silicon-based material, due to the water molecule
attacking the silicon atoms and the Si--N bonds are then severed.
This reaction produces a R.sub.3Si--NH.sub.2 and HO--SiR.sub.3
which further react to form R.sub.3Si--O--SiR.sub.3 siloxane. The
polymerized liquid is clear to translucent, colorless to pale
yellow, and may form a solid. Exposure to higher temperature and/or
sunlight can also increase the mass of the polymerized liquid by
encouraging further thermal or photochemical polymerization. In the
liquid form, trace elements, free ammonia and ammonium chloride can
often be detected.
[0057] Polysilazanes usually do not vaporize due to the strong
molecular interactions. Heat promotes crosslinking of the
polysilazanes to form even higher molecular weight structures. For
example, at temperatures of 100-300.degree. C., hydrogen evolves
and ammonia promotes further crosslinking. As provided in the
present disclosure, vinyl substituents promote continued
crosslinking, increased molecular strength, and conversion of
liquid resins into solids. Once temperatures reach 700-1200.degree.
C., the multi-dimensional amorphous network with Si, C and N atoms
is formed, resulting in a SiCN ceramic. This "pyrolysis" of
polysilazanes produces ceramic materials with low viscosity in high
yield. This also makes the polysilazanes an excellent choice for
precursors for other ceramic matrices. As provided in the present
disclosure, polymers combined with low molecular weight components
offer added value for the generation of resistant and fast-curing
coatings, because new chains can be formed that can improve and
enhance the resulting material properties.
[0058] Alternatively, polysilazane may be commercially available.
For example, polysilazane (<99%) in tert-butyl acetate solvent
manufactured by KiON Defense Technologies, Inc. (Huntingdon Valley,
Pa.) as KDT Ambient Cure Coating Resin (KDT HTA.RTM. 1500), is
supplied as a 100% solids liquid of low viscosity. KDT HTA.RTM.
1500 may comprise more than 99% polysilazane. KDT HTA.RTM. 1500 may
comprise less than 5% cyclosilazane, a cyclic form of polysilazane.
A similar product is also available from other manufacturers,
including AZ Electric Materials (Branchburg, N.J.), the parent
company to KiON. In other embodiments, the silazane may be DT-6062,
DT-6063, or combinations thereof.
[0059] Silazane may comprise from about 0% and about 76% (w/w) of
the total formula weight of silicon-based compositions. In some
embodiments, silazane may comprise about 76%, 70%, 65%, 62%, 57%,
52%, 47%, 42%, 37%, 32%, 27%, 22%, 12%, 10%, 8%, 5%, 4%, 3%, 2%, 1%
(w/w), or any range thereof, of the silicon-based composition. For
example, the amount of silazane present in the silicon-based
composition may range from about 1% to about 3%, from about 2% to
about 4%, from about 4% to about 6%, from about 5% to about 8%,
from about 6% to about 9%, from about 7% to about 10%, from about
8% to about 11%, from about 9% to about 12%, from about 10% to
about 15%, from about 12% to about 22%, from about 18% to about
28%, from about 25% to about 35%, from about 32% to about 42%, from
about 40% to about 50%, from about 48% to about 58%, from about 55%
to about 65%, from about 60% to about 70%, from about 68% to about
76% (w/w), of the total composition. In an exemplary embodiment,
the amount of silazane present in the composition may be from about
2% to about 8%, (w/w) of the total composition. In another
exemplary embodiment, the amount of silazane present in the
composition may be about 4% (w/w) of the total composition.
(c) Silane
[0060] The silicon-based compositions of the present disclosure may
further include a silane. Silanes are compounds which contain one
or more silicon-silicon bonds. Polysilanes
[R.sub.1R.sub.2Si--R.sub.1R.sub.2Si].sub.n are a large family of
inorganic polymers. The number of repeating units, n, determines
the molecular weight and viscosity of the composition. R.sub.1 and
R.sub.2 may be independently selected from the group consisting of
hydrogen, alkyl, alkenyl, cycloalkyl, alkylamino, aryl, aralkyl, or
alkylsilyl. Thus, R.sub.1 and R.sub.2 may be, for example, methyl,
ethyl, propyl, butyl, octyl, decyl, vinyl, allyl, butenyl, octenyl,
decenyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, cyclohexyl,
methylcyclohexyl, methylamino, ethylamino, phenyl, tolyl, xylyl,
naphthyl, benzyl, methylsilyl, ethylsilyl, propylsilyl, butylsilyl,
octylsilyl, or decylsilyl. A polymer with the general formula
--[(CH.sub.3).sub.2Si--(CH.sub.3).sub.2Si]--.sub.n, is designated
as polydimethylsilane. The chemical structure of polydimethylsilane
is shown below:
##STR00013##
[0061] High molecular weight polysilane product with a narrow
molecular weight distribution may be obtained by the process of
U.S. Pat. No. 5,599,892, which is incorporated herein by reference.
Polysilane is also available as a resin system supplied in amyl
acetate blend from Kadko, Inc. (Beech Grove, Ind.), and it is sold
as a KADKLAD R2X3.TM. product. Polysilane as provided in the form
of KADKLAD R2X3 resin may comprise from about 1% and about 9% (w/w)
of the total formula weight of silicon-based compositions. In
exemplary embodiments, the silicon-based composition may comprise
trimethoxysilane, triethoxysilane (TEOS), aminopropylsilane,
aminoproyplmethyldioxysilane, and polysilane. In other embodiments,
the mixture may comprise a silane, such as triethoxysilane (TEOS),
shown below:
##STR00014##
[0062] In one embodiment, the silicon-based composition does not
contain silane. Generally, the amount of silane in the
silicon-based composition ranges from 5% to 80% (w/w). In some
embodiments, silane may comprise about of the total formula weight
of silicon-based composition. In some embodiments, silane may
comprise about 5% 6%, 7% 8%, 9%, 9.9%, 10%, 15%, 16%, 17%, 18%,
19%, 19.9%, 35%, 36%, 37%, 38%, 39%, 39.9%, 40%, 75%, 76%, 77%,
78%, 79%, 79.9%, or 80% (w/w), or any range thereof, of the
silicon-based composition. For example, the amount of silane
present in the silicon-based composition may range from about 5% to
about 10%, from about 10% to about 15%, from about 15% to about
20%, from about 20% to about 25%, from about 25% to about 30%, from
about 30% to about 35%, from about 35% to about 40%, from about 40%
to about 45%, from about 45% to about 50%, from about 50% to about
55%, from about 55% to about 60%, from about 60% to about 65%, from
about 65% to about 70%, from about 70% to about 75%, or from about
75% to about 80% (w/w) of the total composition. In some
embodiments, the silane may comprise less than 80% (w/w) of the
total composition. In other embodiments, the silane may comprise
less than 40% (w/w) of the total composition. In some other
embodiments, the silane may comprise less than 20% (w/w) of the
total composition. In still some other embodiments, the silane may
comprise less than 10% (w/w) of the total composition. In still
other embodiments, the silane may comprise more than 5% (w/w) of
the total composition. In yet other embodiments, the silane may
comprise more than 15% (w/w) of the total composition. In still yet
other embodiments, the silane may comprise more than 35% (w/w) of
the total composition. In some embodiments, the silane may comprise
more than 75% (w/w) of the total composition.
(d) Solvent
[0063] The silicon-based compositions of the current disclosure may
additionally include one or more solvents. The solvent may be a
polar protic solvent, a polar aprotic solvent, or a nonpolar
solvent. Non-limiting examples of suitable protic polar solvents
include water; alcohols such as methanol, ethanol, isopropanol,
n-propanol, isobutanol, n-butanol, s-butanol, t-butanol, and the
like; diols such as propylene glycol; organic acids such as formic
acid, acetic acid, and so forth; amides such as formamide,
acetamide, and the like; and combinations of any of the above.
Non-limiting examples of suitable aprotic solvents include acetone,
acetonitrile, diethoxymethane, N,N-dimethylformamide (DMF),
dimethyl sulfoxide (DMSO), N,N-dimethylpropanamide (or
dimethylpropionamide; DMP),
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU),
1,3-dimethyl-2-imidazolidinone (DMI), 1,2-dimethoxyethane (DME),
dimethoxymethane, bis(2-methoxyethyl)ether, N,N-dimethylacetamide
(DMA), N-methyl-2-pyrrolidinone (NMP), 1,4-dioxane, ethyl formate,
formamide, hexachloroacetone, hexamethylphosphoramide, methyl
acetate, N-methylacetamide, N-methylformamide, methylene chloride,
methoxyethane, morpholine, nitrobenzene, nitromethane,
propionitrile, pyridine, sulfolane, tetramethylurea,
tetrahydrofuran (THF), 2-methyl tetrahydrofuran, tetrahydropyran,
trichloromethane, and combinations thereof. Representative nonpolar
solvents include, but are not limited to, alkane and substituted
alkane solvents (including cycloalkanes), aromatic hydrocarbons,
esters, ethers, ketones, and combinations thereof. Specific polar
protic solvents that may be employed include, for example,
methanol, ethanol, n-propanol, isopropanol, n-butanol,
tert-butanol, amyl alcohol, pentyl alcohol, isoamyl alcohol, and
combinations thereof.
[0064] In exemplary embodiments, the solvent may comprise
n-butanol, methyl acetate, tert-butyl acetate, isopropyl acetate,
isoalkanes, and combinational thereof. The ratio of solvents may be
selected to control the dry time of the silicon-based composition,
especially under cooler ambient temperatures. In other embodiments,
the solvent may be IsoPar.TM. G (isoalkanes, hydrotreated heavy
naphta, ExxonMobil) used in combination with tert-butyl acetate.
The ratio of IsoPar.TM. G to tert-butyl acetate may be selected to
extend the dry time of the silicon-based composition in hotter
ambient temperatures.
[0065] In general, the organic solvent comprises from about 0% to
about 98% (w/w) of the silicon-based composition. In some
embodiments, the solvent may comprise about 98%, about 95%, about
90%, about 85%, about 80%, about 75%, about 70%, about 65%, about
60%, about 55%, about 40%, about 35%, about 30%, about 25%, about
20%, about 15%, about 10%, or about 5% (w/w) of the total
composition.
(e) Additives
[0066] The silicon-based compositions of the current disclosure may
further comprise one or more additives, including, but not limited
to curing agents, pigments, tracing dyes, fillers, flow control
agents, dry flow additives, anti-cratering agents, surfactants,
texturing agents, light stabilizers, matting agents,
photosensitizers, wetting agents, anti-oxidants, plasticizers,
opacifiers, stabilizers, ceramic microspheres, slip agents,
dispersing agents, mica pigments, and surface altering additives.
Additives typically comprise less than about 30% of the total
silicon-based composition. In some embodiments, the additive
comprises about 30%, about 25%, about 20%, about 15%, about 10%,
about 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.1%, or 0% (w/w) of the
total composition.
[0067] (i) Enhancer/Hardeners
[0068] In some embodiments of the present disclosure, each polymer
in the composition can be cured independently without the need of
forming co-polymers. In other embodiments, substances or mixtures
of substances may be added to a resin to promote or control the
curing reaction, for example curing agents such as catalysts,
enhancers, and hardeners. As is generally known in the art, curing
enhancers increase the rate of a chemical reaction as an initiator.
The enhancer is added in a small quantity as compared to the
amounts of primary reactants, and does not become a component part
of the chain. In contrast, curing hardener, often an amine, enables
the formation of a complex three-dimensional molecular structure by
chemical reaction between the polymers and the amine. It is
essential that the correct mix ratio is obtained between resin and
hardener to ensure that a complete reaction takes place, such that
no unreacted resin or hardener will remain within the matrix to
affect the final properties after cure. Conventional polyamine
hardeners comprise primary or secondary amine groups. A
polysilazane-modified polyamine hardener was described in U.S. Pat.
No. 6,756,469 (incorporated herein by reference), providing heated
polyamine in the presence of a polysilazane to prepare a hardener
imparting enhanced high temperature properties, higher char yields,
and better adhesion properties.
[0069] In a particular embodiment, vinyl groups present in the
silicon-based constituents may act as reaction promoters,
increasing the rate and extent of polymerization of the coating
during curing. The vinyl groups may be present in any one or more
of the constituents of the silicon-based compositions, for example,
within the silazane, siloxane, or silane constituent. During
polymerization, the vinyl groups are substantially consumed,
forming new covalent bonds within crosslinked polymer network of
the cured coating. The concentration and distribution of vinyl
groups within the coating.
[0070] In other embodiments, the enhancer may be an alkyltitanate,
such as a polymeric butyltitanate (also referred to as a titanium
butanolate polymer), for example Tyzor.TM. BTP, consisting of 5 to
25 dibutoxytitanate repeating units. The FTIR spectrum for
Tyzor.TM. BTP is depicted at FIG. 2 and indicates low
concentrations (<2 ppm) of residual toluene and methanol in the
bulk material. The structure of Tyzor.TM. BTP is shown below:
##STR00015##
In other embodiments, the alkyltitanate may be a non-polymeric
butyltitanate, such as Tyzor.TM. TnBP. When used, the Tyzor.TM.
TnBP may have a concentration of 0.5 wt. % to 2 wt. % of the total
resin weight. Monomeric butyltitante results faster curing
shortened by about 20 to about 30 minutes compared to using a
polymeric butyltitanate, depending on the formulation. The
butyltitanate may be provided in a polar solvent, such as an
alcohol, for example n-butanol. While the alkyltitanate is
non-volatile, n-butanol has a vapor pressure of <7 hPa (<5
mmHg) at 25.degree. C. (77.degree. F.) and is flammable, with a
flash point of 68.degree. C. (154.degree. F.). The butyltitanate
may be hydrolyzed, rendering the material non-reactive and
resulting in non-toxic titanium dioxide. Typically, a detectable
amount of water, such as humidity from the atmosphere, allows the
butyltitanate to react with a siloxane, such as a silsesquioxane or
a methylmethoxysiloxane (Silres.RTM.).
[0071] The amount of alkyltitanate in the silicon-based composition
can and will vary. Generally, the concentration of alkyltitanate
ranges from about 0.1% to about 10% (w/w) of the total composition.
In exemplary embodiments, the concentration of alkyltitanate may
range from about 0.1% to about 0.5%, about 0.5% to about 1%, about
1% to about 2%, about 2% to about 3%, about 3% to about 4%, about
4% to about 5%, about 5% to about 6%, about 6% to about 7%, about
7% to about 8%, about 8% to about 9%, or about 9% to about 10%
(w/w). In some embodiments, the alkyltitanate may comprise less
than 10% (w/w) of the total composition. In other embodiments, the
alkyltitanate may comprise more than 0.1% (w/w) of the total
composition. In particular embodiments, the concentration of
alkyltitanate may range from about 0.1% to about 5% (w/w). In other
particular embodiments, the concentration of alkyltitanate may
range from about 2% to about 5% (w/w). In still other particular
embodiments, the concentration of alkyltitanate may range from
about 0.5% to about 2% (w/w).
[0072] (ii) Substituents
[0073] The silicon-based compositions of the current disclosure may
further include one or more organic or inorganic substituents. The
optional organic or inorganic substituents may be added to
introduce reactive groups into the reaction and thus to the
copolymer. For example, by selecting the organochlorosilanes used,
the polymerizable side chains of the copolymer may vary. Suitable
organochlorosilanes that may be added include, but not limited to,
chloromethylvinylsilane, chlorodivinylsilane,
dichloroethylvinylsilane, dichloromethylvinylsilane, and
chloroethylmethyldivinylsilane. When present, vinyl groups may
react with other compounds of low molecular weight that are mixed
with the constituents before curing. These changes in the reaction
process increase the chain length and the degree of
three-dimensional crosslinking of the resulting
macromolecule-networks. As a result, they have much higher mass
ranges and significantly improved material properties.
[0074] (iii) Matting Agents
[0075] The matting agents used in the practice of this disclosure
typically can alter the surface of a coating in such a way that the
light falling on it is scattered in a defined fashion. The matting
agent particles stand out from the coating, and are invisible to
the human eye. The color of the coating is not affected to any
great extent. Representative examples of such matting agents
include inorganic matting agents such as silica-based Acematt.RTM.
matting agents from Evonik Degussa (Parsippany, N.J.) and
silica-based matting agents available from Ineos Silicas
(Hampshire, United Kingdom). The matting agents may vary in size
and include materials that are micron sized particles. For example,
the particles may have an average diameter of from about 0.1 to
1000 microns, and in one embodiment from 0.1 to 100 microns.
Combinations of matting agents may be used.
(II) Polymers Formed from Silicon-Based Compositions
[0076] In various embodiments, the present disclosure also provides
a silicon-based polymer, comprising a siloxane ladder structure.
The polymer is formed from the polymerization of a mixture
comprising silsesquioxane, and one or more silicon compounds
selected from the group consisting of a second siloxane, silane,
and silazane. The constituents of the mixture are as described
above in Section (I), and may optionally comprise an
alkyltitanate.
[0077] In exemplary embodiments, the silsesquioxane may be
methylsilsesquioxane. In other embodiments, the mixture may further
comprise methylmethoxysiloxane. In some embodiments, the
alkyltitanate may be butyltitanate present in a enhancer-effective
amount. In particular embodiments, the mixture may comprise from
about 2% to about 5% butyltitanate (w/w).
[0078] In particular, the polymer may comprise a siloxane ladder
structure comprising a repeating unit of formula (I),
##STR00016##
[0079] wherein each R.sup.1 is hydrocarbyl, and wherein n is
between 4 and 100.
[0080] In some embodiments, each R.sup.1 may be alkyl. In other
embodiments, each R.sup.1 may be C.sub.1-C.sub.20 alkyl. In some
other embodiments, each R.sup.1 may be C.sub.1-C.sub.10 alkyl. In
still other embodiments, each R.sup.1 may be C.sub.1-C.sub.8 alkyl.
In yet other embodiments, each R.sup.1 may be selected from the
group consisting of methyl, ethyl, propyl, and butyl. In exemplary
embodiments, each R.sup.1 may be methyl.
[0081] The number n may range from 1 to 100, such as 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
92, 93, 94, 95, 96, 97, 98, 99, or 100. In some embodiments, n is
less than 100. In some other embodiments, n is greater than 1. In
exemplary embodiments, n is 4.
(III) Method for Forming a Silicon-Based Composition
[0082] In various embodiments, the present disclosure provides a
method for forming a silicon-based polymer comprising a siloxane
ladder structure. In particular, the method may be used to apply or
form a coating a surface. The method comprises (a) mixing a mixture
of constituents to form a silicon-based coating composition
comprising from about 20% to about 90% (w/w) of a first siloxane
selected from the group consisting of silsesquioxane,
methylmethoxysiloxane, and combinations thereof; and from about 10%
to about 80% (w/w) of one or more silicon compounds selected from
the group consisting of a second siloxane, silane, and silazane.
(b) The mixture is coated onto a surface, and (c) the coating is
cured at a temperature from about 20.degree. C. to about
400.degree. C. for about 0.3 hours to about 5 days.
[0083] In some embodiments, the first siloxane may comprise a
combination of from about 10% to about 70% (w/w)
methylsilsesquioxane and from about 10% to about 50% (w/w)
methylmethoxysiloxane; the silicon compound may comprise a
combination of from about 10% to about 50% (w/w) triethoxysilane,
and from about 10% to about 20% methylphenylsiloxane resin; and an
alkyltitanate may comprise from about 0.5% to about 2% (w/w)
butyltitanate. Further ratios and variations may be as described
above in Section (I).
[0084] The curing step may be conducted at a temperature that
ranges from about 20.degree. C. to about 400.degree. C. In one
embodiment, the temperature of the reaction may range from about
20.degree. C. to about 30.degree. C., from about 30.degree. C. to
about 40.degree. C., from about 40.degree. C. to about 50.degree.
C., from about 50.degree. C. to about 60.degree. C., from about
60.degree. C. to about 70.degree. C., from about 70.degree. C. to
about 80.degree. C., from about 80.degree. C. to about 90.degree.
C., from about 90.degree. C. to about 100.degree. C., from about
100.degree. C. to about 125.degree. C., from about 125.degree. C.
to about 150.degree. C., from about 150.degree. C. to about
200.degree. C., from about 200.degree. C. to about 250.degree. C.,
from about 250.degree. C. to about 300.degree. C., from about
300.degree. C. to about 350.degree. C., or from about 350.degree.
C. to about 400.degree. C. In some embodiments, the temperature may
range from about 20.degree. C. to about 30.degree. C. In some
embodiments, the temperature may range from about 60.degree. C. to
about 120.degree. C. In some embodiments, the temperature may range
from about 60.degree. C. to about 70.degree. C. In other
embodiments, the temperature may range from about 300.degree. C. to
about 400.degree. C. In still other embodiments, the temperature
may less than about 400.degree. C. In some other embodiments, the
temperature may more that about 20.degree. C. In some other
embodiments, the temperature may more that about 50.degree. C. The
reaction may be performed under ambient pressure or in an inert
atmosphere (e.g., nitrogen or argon).
[0085] The curing step may be conducted over a time that ranged
from about 0.3 hours to about 5 days. In one embodiment, the time
of the reaction may range from about 0.3 hours to about 0.5 hours,
from about 0.5 hours to about 1 hour, from about 1 hour to about 2
hours, from about 2 hours to about 4 hours, from about 4 hours to
about 6 hours, from about 6 hours to about 8 hours, from about 8
hours to about 10 hours, from about 10 hours to about 12 hours,
from about 12 hours to about 14 hours, from about 14 hours to about
16 hours, from about 16 hours to about 18 hours, from about 18
hours to about 20 hours, from about 20 hours to about 22 hours,
from about 22 hours to about 24 hours, about 1 day, about 2 days,
about 3 days, about 4 days, or about 5 days. In other embodiments,
the time may range from about 1 day to about 5 days. In some
embodiments, the time may range from about 2 hours to about 24
hours. In other embodiments, the time may range from about 0.3
hours to about 5 hours. In other embodiments, the time may range
from about 1 hour to about 3 hours. In still other embodiments, the
time may be less than 24 hours. In yet other embodiments, the time
may be more than 0.3 hours.
[0086] In some instances, the coating may be cured at a temperature
of about 20.degree. C. to about 30.degree. C. for about 1 day to
about 5 days to form the coating composition. In some instances,
the coating may be cured at a temperature of about 60.degree. C. to
about 70.degree. C. for about 2 hours to about 24 hours to form the
coating composition. In some instances, the coating may be cured at
a temperature of about 60.degree. C. to about 120.degree. C. for
about 1 hour to about 2 hours to form the coating composition. In
other instances, the coating may be cured at a temperature of about
300.degree. C. to about 400.degree. C. for about 0.3 to about 5
hours to form the coating composition.
(IV) Coatings of Silicon-Based Compositions
[0087] The silicon-based compositions described herein may be
further processes for a variety of applications, including forming
coatings.
[0088] The resin may be applied by dipping, spraying, brushing,
painting, wiping, immersion, or spin-coating techniques. These
procedures typically provide polymer coatings of thicknesses on the
order of 1 .mu.m or thinner, to up to about 75 .mu.m per coat for
the cured polymers. If a thicker coating is desired, multiple
coating layers may be provided. The resins as provided herein
result in a coating transparent and therefore do not affect the
optical appearance of the substrate. Due to the small coating
thicknesses, only a very small amount of material is used, which is
advantageous both in terms of cost and also ecologically, and the
weight change of the substrate to be coated is nearly unnoticeable.
The coating thickness of the silicon-based coating as provided
herein following evaporation of the solvent and curing is in the
range from about 0.1 .mu.m to about 50 .mu.m. In some embodiments
the coating thickness is from about 0.5 .mu.m to about 40 .mu.m. In
some embodiments, the coating thickness is from about 0.1 .mu.m to
about 25 .mu.m. In some other embodiments, the coating thickness is
from about 1 .mu.m to about 3 .mu.m.
[0089] "Curing" refers to the process of polymerization after the
coating is applied. Curing may be controlled through temperature,
air flow, ratio of the solvents, choice of resin and hardener
compounds, and the ratio of said compounds. The curing process can
take minutes to hours. Some formulations benefit from heating
during the cure period, whereas typically the formulation cures
over time at ambient temperature. In other situations, the curing
can be at elevated temperatures to increase the glass transition
(Tg) properties of the finished coating product by enhancing the
degree of crosslinking. Coatings ambiently cured may be at room
temperature ranging from 5-40.degree. C. By heating slightly, the
curing time can be shortened. Curing may be performed at
temperatures not exceeding about 100.degree. C. Higher temperature
may be applied as needed. The curing atmosphere may include, but is
not limited to, air and other non-reactive or reactive gaseous
environments which contain moisture, inert gases like nitrogen and
argon, and reactive gases such as ammonia, hydrogen, carbon
monoxide, and the like. Rapid cure times are achieved using this
method when the applied coatings are exposed to the
moisture-containing atmosphere at room temperature.
[0090] Coating-related testing provides quality control and product
description based on industrial standards. Typical coating tests
may include, but not be limited to, testing thickness, coefficient
of friction, hardness, scratch resistance, the amount of force
needed to scratch the coating from substrate; 90 degree peel from
topcoat test; 90 degree peel from adhesive test; cross-hatch
adhesion test; UV endurance test; heat stability test; conical bend
test, impact direct and indirect test. In particular, thickness
test, measuring the thickness of substrates and top-coated
materials, may be carried out using test panels on which uniform
films are produced by a coating suitable for spraying; using
micrometers for dried films; using magnetic gauges for nonmagnetic
coatings; using Wet Film Thickness Gauge or Pfund Gauge for wet
film thickness; or using microscopic observation of precision
angular cuts in the coating film. Hardness test of organic
materials may be carried out using indentation hardness
measurements, Sward-type hardness rocker instruments, or pendulum
damping testers.
[0091] In addition, the "kinetic coefficient of friction" (COF,
.mu.), also known as a "frictional coefficient" or "friction
coefficient," describes the ratio of the force of friction between
two bodies and the force pressing them together. Coefficients of
friction range from near zero to greater than one. Rougher surfaces
tend to have higher effective values. The COF measured under ASTM
D1894 is called Standard COF. More standard ASTM (American Society
for Testing and Materials) test methods for coatings are available
at http://wernerblank.com/polyur/testmethods/coating_test.htm. In
one embodiment, the thickness of the silicon-based coating resulted
from the compositions provided herein is between from about 0.1
.mu.m to about 45 .mu.m. In one embodiment, the hardness of the
silicon-based coating resulted from the compositions provided
herein ranges from about 4H to about 9H, using ASTM D3363. Further,
in one embodiment, the COF of the silicon-based coating resulted
from the compositions provided herein is between from about 0.03 to
about 0.04.
[0092] Surfaces, substrates and substrate layers suitable for
resins provided herein may comprise any desirable substantially
solid material that varies widely. For example, the type of
surfaces that can be treated with the compositions of this
disclosure includes glass; fiberglass; carbon fiber composites;
basalt fiber composites; siloxane and ceramic fibers; ceramics,
such as, silicon nitride, silicon carbide, silica, alumina,
zirconia, and the like; metals, such as, for example, iron,
stainless steel, galvanized steel, zinc, aluminum, nickel, copper,
magnesium and alloys thereof, silver and gold and the like;
plastics, such as, polymethyl methacrylate, polyurethane,
polycarbonate, polyesters including polyethylene terephthalate,
polyimides, polyamides, epoxy resins, ABS polymer, polyethylene,
polypropylene, polyoxymethylene; porous mineral materials, such as,
concrete, clay bricks, marble, basalt, asphalt, loam, terracotta;
organic materials, such as wood, leather, parchment, paper and
textiles; and coated surfaces, such as, plastics emulsion paints,
acrylic coatings, epoxy coatings, melamine resins, polyurethane
resins and alkyd coatings. The surface or substrate contemplated
herein may also comprise at least two layers of materials. One
layer of material, for example, may include glass, metal, ceramic,
plastics, wood or composite material. Other layers of material
comprising the surface or substrate may include layers of polymers,
monomers, organic compounds, inorganic compounds, organometallic
compounds, continuous layers, porous and nanoporous layers.
[0093] Further, the surfaces and substrates may have different
shapes, e.g., substrates having flat, planar surfaces, molded
articles having curved surfaces, fibers, fabrics, and the like. It
will be appreciated by those skilled in the art that the foregoing
lists are merely illustrative of various materials which may be
coated using the presently disclosed compositions and methods, and
are not in any way limiting of the different substrates with which
the present disclosure is useful. Insofar as they protect virtually
any type of substrate from oxidative thermal degradation,
corrosion, or chemical attack. The coatings may also be used to
strengthen relatively flaw sensitive brittle substrates such as
glass and non-wetting surfaces. The coatings may additionally be
useful to provide bonding or compatibility interfaces between
different types of materials.
[0094] A particularly advantageous, but non-limiting, use of this
coating is for surfaces that undergo high pressure and temperature,
and multiple pulls. A protective film provided by the silicon-based
compositions disclosed herein over the base layer of paint or
surface material of these surfaces is particularly useful to
provide long lasting protection, in comparison to other materials
in market, from various external forces, which can be destructive
over a period of time. Other advantageous, but non-limiting, use of
the coatings provided herein is to coat on automobile, aircraft,
missiles, aerospace components, marine vessels, wheels, wind
generation equipment and blades, engine shrouds, car exhausts,
smoke stacks, industrial kilns, combustion chambers, industrial
duct and pipe systems, solar panels, electronic components, fire
and safety appliance, insulation and energy systems, building
surfaces, public spaces, packaging surfaces, outdoor signs and
advertisement billboard or LED screens, food- and
beverage-processing equipment, cookware and containers. Those
surfaces are exposed to UV, heat, coldness, moisture, ice build-up,
chemical corrosion, and wear and tear from natural physical forces
creating friction such as, water, air flow and dust. In addition,
such protection is particularly suitable for mechanical components
exposed to high temperatures, including, for example, exterior
aircraft surfaces, a wing slat or pylon made of titanium, aluminum
or cress metal; heat shields on an aircraft or other coated
aircraft areas subject to engine efflux. A protective film provided
by the silicon-based compositions disclosed herein over the base
layer of paint or surface material of these surfaces is
particularly useful to protect the surface and the substrate
material from various external forces, particularly from the heat
and high temperature, by greatly reducing radiant heat passing
through the surface and the substrate material.
[0095] In exemplary embodiments, the coating may be formed on a
medical device. In some embodiments, the medical device may be
selected from the group consisting of catheter, surgical
instrument, implant, heart valve, vascular graft, sensor, stent,
annulus, insulator for electrical leads, extracorporeal blood-loop
circuit, implantable cardiac assist device for prolonged
circulatory support, left ventricular assist device (LVAD),
polyethylene braid, artificial cord, tether, suture, peripherally
inserted central catheter (PICC) line, fistula plug, membrane,
blood bag; blood processing, transportation and storage equipment
and materials; Luer connector, aneurysm patch, conduit, coil,
roller pump, patent foramen ovale (PFO), reconstruction patch,
transapical device, angioplasty tool, cannula, and annuloplasty
ring. The surgical instrument may beselected from the group
consisting of grasper, forceps, clamp, retractor, distractor,
cutter, scalpel, lancet, drill bit, rasp, trocar, dilator, specula,
suction tip, suction tube, sealing device, irrigation needle,
injection needle, Tyndaller, drill, dermatome, scope, probe,
endoscope, ultrasonic tissue disruptor, ruler, and caliper. In
particular embodiments, the implant may be an orthopedic implant,
for example, selected from the group consisting of Austin-Moore
prosthesis, Baksi's prosthesis, buttress plate, charnley
prosthesis, condylar blade plate, dynamic compression plate,
Ender's nail, Gross-Kempf nail, Harrington rod, Hartshill
rectangle, Insall Burstein prosthesis, interlocking nail, Kirschner
wire, Kuntscher nail, Luque rod, Moore's pin, Neer's prosthesis,
Rush nail, Smith Peterson nail, McLaughlin's plate, Seidel nail,
Souter's prosthesis, Steffee plate, Steinmann pin, Swanson
prosthesis, Talwalkar nail, Thompson prosthesis, unicompartmental
knee.
[0096] The cured coating is formed from any of the silicon-based
composition described herein, and may be cured by any disclosed
method, particularly by exposing the substrate coated with a resin
to ambient conditions at room temperature for about 24 hours, or
less. Within the cured coating, silicon-based substituents are
substantially completely reacted to form new covalent bonds to each
other and to the substrate. Furthermore, if the resin contained
substituents bearing vinyl groups, the C.dbd.C bonds are also
consumed in the formation of new covalent bonds. Overall, the
coating comprises a crosslinked polymer network comprising Si--O,
Si--N, and Si--C bonds, especially when both the Si--N and the
Si--O bonds are part of the same polymer network within the
coating. The coating may also substantially free of ammonia, free
amines, or ammonium chloride. The cross-linked polymer provides a
durable and hard coating, as described throughout this
specification.
[0097] In particular, the cured coating may comprise a compound of
formula (II),
##STR00017##
[0098] wherein:
[0099] each R.sup.1 is hydrocarbyl;
[0100] each R.sup.2 is alkyl;
[0101] each A is selected from the group consisting of
##STR00018##
[0102] each R.sup.3 is selected from the group consisting of alkyl
and SiH(OR.sup.4).sub.2;
[0103] each R.sup.4 is selected from the group consisting of methyl
and ethyl;
[0104] n is between 4 and 100; and
[0105] x, y, and z are each between 1 and 100.
[0106] In some embodiments, each R.sup.1 may be alkyl. In other
embodiments, each R.sup.1 may be C.sub.1-C.sub.20 alkyl. In some
other embodiments, each R.sup.1 may be C.sub.1-C.sub.10 alkyl. In
still other embodiments, each R.sup.1 may be C.sub.1-C.sub.8 alkyl.
In yet other embodiments, each R.sup.1 may be selected from the
group consisting of methyl, ethyl, propyl, and butyl. In exemplary
embodiments, each R.sup.1 may be methyl.
[0107] In some embodiments, each R.sup.2 may be C.sub.1-C.sub.20
alkyl. In some other embodiments, each R.sup.2 may be
C.sub.1-C.sub.10 alkyl. In still other embodiments, each R.sup.2
may be C.sub.1-C.sub.8 alkyl. In yet other embodiments, each
R.sup.2 may be selected from the group consisting of methyl, ethyl,
propyl, and butyl. In exemplary embodiments, each R.sup.2 may be
butyl.
[0108] In some embodiments, each R.sup.3 may be C.sub.1-C.sub.20
alkyl. In some other embodiments, each R.sup.3 may be
C.sub.1-C.sub.10 alkyl. In still other embodiments, each R.sup.3
may be C.sub.1-C.sub.8 alkyl. In yet other embodiments, each
R.sup.3 may be selected from the group consisting of methyl, ethyl,
propyl, and butyl.
[0109] The number x may range from 0 to 100, such as 0, 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,
57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,
74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
91, 92, 93, 94, 95, 96, 97, 98, 99, or 100. In one embodiment, x
may range from 5 to 25. In some embodiments, x is less than 100. In
some other embodiments, x is less than 25. In yet other
embodiments, x is greater than 1. In still other embodiments, x is
greater than 5.
[0110] The number y may range from 1 to 100, such as 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
92, 93, 94, 95, 96, 97, 98, 99, or 100. In one embodiment, y may
range from 5 to 25. In some embodiments, y is less than 100. In
some other embodiments, y is less than 25. In yet other
embodiments, y is greater than 1. In still other embodiments, y is
greater than 5.
[0111] The number z may range from 1 to 100, such as 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
92, 93, 94, 95, 96, 97, 98, 99, or 100. In one embodiment, z may
range from 5 to 25. In some embodiments, z is less than 100. In
some other embodiments, z is less than 25. In yet other
embodiments, z is greater than 1. In still other embodiments, z is
greater than 5.
[0112] In exemplary embodiments, the numbers x, y, and z may each
be between 5 and 25.
[0113] The number n may range from 1 to 100, such as 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
92, 93, 94, 95, 96, 97, 98, 99, or 100. In some embodiments, n is
less than 100. In some other embodiments, n is greater than 1. In
exemplary embodiments, n is 4.
[0114] In a particular embodiment of this aspect, the compound of
formula (II) may comprise a compound of formula (III):
##STR00019##
[0115] A and n may be as defined above for formula (II) or any
embodiments thereof.
[0116] Although the disclosure described herein is susceptible to
various modifications and alternative iterations, specific
embodiments thereof have been described in greater detail above. It
should be understood, however, that the detailed description of the
composition is not intended to limit the disclosure to the specific
embodiments disclosed. Rather, it should be understood that the
disclosure is intended to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the disclosure
as defined by the claim language.
DEFINITIONS
[0117] As used herein, the terms "about" and "approximately"
designate that a value is within a statistically meaningful range.
Such a range can be typically within 20%, more typically still
within 10%, and even more typically within 5% of a given value or
range. The allowable variation encompassed by the terms "about" and
"approximately" depends on the particular system under study and
can be readily appreciated by one of ordinary skill in the art.
[0118] As used herein, the term "w/w" designates the phrase "by
weight," "weight percent," or "wt. %," and is used to describe the
concentration of a particular substance in a mixture or
solution.
[0119] As used herein, the term "ml/kg" designates milliliters of
composition per kilogram of formula weight.
[0120] As used herein, the term "cure" or "curing" refers to a
change in state, condition, and/or structure in a material that is
usually, but not necessarily, induced by at least one variable,
such as time, temperature, moisture, radiation, presence and
quantity in such material of a enhancer, accelerator, or the like.
The terms cover partial as well as complete curing.
[0121] As used herein, the term "hardness" or "H" designates the
property of a material that enables it to resist plastic
deformation, usually by penetration. However, the term hardness may
also refer to resistance to bending, scratching, abrasion or
cutting. The usual method to achieve a hardness value is to measure
the depth or area of an indentation left by an indenter of a
specific shape, with a specific force applied for a specific time.
There are four principal standard test methods for expressing the
relationship between hardness and the size of the impression, these
being Pencil Hardness ASTM D3363, Brinell, Vickers, and Rockwell.
For practical and calibration reasons, each of these methods is
divided into a range of scales, defined by a combination of applied
load and indenter geometry.
[0122] As used herein, the term "coefficient of friction" (COF),
also known as a "frictional coefficient" or "friction coefficient"
or "kinetic coefficient of friction" and is an empirical
measurement which describes the ratio of the force of friction
between two bodies and the force pressing them together. The
coefficient of friction depends on the materials used. When the
coefficient of friction is measured by a standardized surface, the
measurement is called "standardized coefficient of friction."
[0123] As used herein, the term "corrosion resistant agent" or
variation thereof refers to additives in the coating on a surface
which inhibit the corrosion of the surface substrate when it is
exposed to air, heat, or corrosive environments for prolonged time
periods.
[0124] By "oligomer" is meant any molecule or chemical compound
which comprises several repeat units, generally from about 2 to 10
repeat units. "Polymer" or "copolymer", as used herein, means a
molecule or compound which comprises a large number of repeat
units, generally greater than about 10 repeat units.
[0125] As used herein, the term "monomer" refers to any chemical
compound that is capable of forming a covalent bond with itself or
a chemically different compound in a repetitive manner. The
repetitive bond formation between monomers may lead to a linear,
branched, super-branched, or three-dimensional product.
Furthermore, monomers may themselves comprise repetitive building
blocks, and when polymerized the polymers formed from such monomers
are then termed "blockpolymers." Monomers may belong to various
chemical classes of molecules including organic, organometallic or
inorganic molecules. The molecular weight of monomers may vary
greatly between about 40 Daltons and 20,000 Daltons. However,
especially when monomers comprise repetitive building blocks,
monomers may have even higher molecular weights. Monomers may also
include additional reactive groups.
[0126] Contemplated polymers may also comprise a wide range of
functional or structural moieties, including aromatic systems, and
halogenated groups. Furthermore, appropriate polymers may have many
configurations, including a homopolymer, and a heteropolymer.
Moreover, alternative polymers may have various forms, such as
linear, branched, super-branched, or three-dimensional. The
molecular weight of contemplated polymers spans a wide range,
typically between 400 Daltons and 400,000 Daltons or more.
[0127] "Prepolymer" refers to polymeric structures formed by the
processes in the present disclosure are long term-stable liquids,
and possess only moderate odors, which mostly arise from the use of
organic solvents. In the solid form, these polymerized materials
may be handled similarly to thermosetting or thermoplastic
processes. Molecular weight may vary from about 2,000 g/mol up to
as much as 100,000 g/mol, depending on process. The density of the
prepolymers is normally around 1 g/cm.sup.3.
[0128] The polymerization processes include, but are not limited
to, step-growth polymerization, polyaddition, and polycondensation.
More specifically, polymerization can be initiated by mechanisms,
such as acid- or base-catalysis, or free radical polymerization. It
may comprise ring-opening copolymerization, and the formation of
inorganic and/or organic polymer networks. The actual mechanisms of
polymerization depend on the functional groups of the reacting
polymeric and monomeric compounds, as well as inherent steric
effects. Adding non-conventional starting materials into the
polymerization process, such as ammonia, can form conceptually new
materials.
[0129] The compounds described herein have asymmetric centers.
Compounds of the present disclosure containing an asymmetrically
substituted atom may be isolated in optically active or racemic
form. All chiral, diastereomeric, racemic forms and all geometric
isomeric forms of a structure are intended, unless the specific
stereochemistry or isomeric form is specifically indicated.
[0130] The term "acyl," as used herein alone or as part of another
group, denotes the moiety formed by removal of the hydroxy group
from the group COOH of an organic carboxylic acid, e.g., RC(O)--,
wherein R is R.sup.1, R.sup.1O--, R.sup.1R.sup.2N--, or R.sup.1S--,
R.sup.1 is hydrocarbyl, heterosubstituted hydrocarbyl, or
heterocyclo, and R.sup.2 is hydrogen, hydrocarbyl, or substituted
hydrocarbyl.
[0131] The term "acyloxy," as used herein alone or as part of
another group, denotes an acyl group as described above bonded
through an oxygen linkage (O), e.g., RC(O)O-- wherein R is as
defined in connection with the term "acyl."
[0132] The term "allyl," as used herein not only refers to compound
containing the simple allyl group (CH.sub.2.dbd.CH--CH.sub.2--),
but also to compounds that contain substituted allyl groups or
allyl groups forming part of a ring system.
[0133] The term "alkyl" as used herein describes groups which are
preferably lower alkyl containing from one to eight carbon atoms in
the principal chain and up to 20 carbon atoms. They may be straight
or branched chain or cyclic and include methyl, ethyl, propyl,
isopropyl, butyl, hexyl and the like.
[0134] The term "alkenyl" as used herein describes groups which are
preferably lower alkenyl containing from two to eight carbon atoms
in the principal chain and up to 20 carbon atoms. They may be
straight or branched chain or cyclic and include ethenyl, propenyl,
isopropenyl, butenyl, isobutenyl, hexenyl, and the like.
[0135] The term "alkynyl" as used herein describes groups which are
preferably lower alkynyl containing from two to eight carbon atoms
in the principal chain and up to 20 carbon atoms. They may be
straight or branched chain and include ethynyl, propynyl, butynyl,
isobutynyl, hexynyl, and the like.
[0136] The term "aromatic" as used herein alone or as part of
another group denotes optionally substituted homo- or heterocyclic
conjugated planar ring or ring system comprising delocalized
electrons. These aromatic groups are preferably monocyclic (e.g.,
furan or benzene), bicyclic, or tricyclic groups containing from 5
to 14 atoms in the ring portion. The term "aromatic" encompasses
"aryl" groups defined below.
[0137] The terms "aryl" or "Ar" as used herein alone or as part of
another group denote optionally substituted homocyclic aromatic
groups, preferably monocyclic or bicyclic groups containing from 6
to 10 carbons in the ring portion, such as phenyl, biphenyl,
naphthyl, substituted phenyl, substituted biphenyl, or substituted
naphthyl.
[0138] The terms "carbocyclo" or "carbocyclic" as used herein alone
or as part of another group denote optionally substituted, aromatic
or non-aromatic, homocyclic ring or ring system in which all of the
atoms in the ring are carbon, with preferably 5 or 6 carbon atoms
in each ring. Exemplary substituents include one or more of the
following groups: hydrocarbyl, substituted hydrocarbyl, alkyl,
alkoxy, acyl, acyloxy, alkenyl, alkenoxy, aryl, aryloxy, amino,
amido, acetal, carbamyl, carbocyclo, cyano, ester, ether, halogen,
heterocyclo, hydroxy, keto, ketal, phospho, nitro, and thio.
[0139] The terms "halogen" or "halo" as used herein alone or as
part of another group refer to chlorine, bromine, fluorine, and
iodine.
[0140] The term "heteroatom" refers to atoms other than carbon and
hydrogen.
[0141] The term "heteroaromatic" as used herein alone or as part of
another group denotes optionally substituted aromatic groups having
at least one heteroatom in at least one ring, and preferably 5 or 6
atoms in each ring. The heteroaromatic group preferably has 1 or 2
oxygen atoms and/or 1 to 4 nitrogen atoms in the ring, and is
bonded to the remainder of the molecule through a carbon. Exemplary
groups include furyl, benzofuryl, oxazolyl, isoxazolyl,
oxadiazolyl, benzoxazolyl, benzoxadiazolyl, pyrrolyl, pyrazolyl,
imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidyl, pyrazinyl,
pyridazinyl, indolyl, isoindolyl, indolizinyl, benzimidazolyl,
indazolyl, benzotriazolyl, tetrazolopyridazinyl, carbazolyl,
purinyl, quinolinyl, isoquinolinyl, imidazopyridyl, and the like.
Exemplary substituents include one or more of the following groups:
hydrocarbyl, substituted hydrocarbyl, alkyl, alkoxy, acyl, acyloxy,
alkenyl, alkenoxy, aryl, aryloxy, amino, amido, acetal, carbamyl,
carbocyclo, cyano, ester, ether, halogen, heterocyclo, hydroxy,
keto, ketal, phospho, nitro, and thio.
[0142] The terms "heterocyclo" or "heterocyclic" as used herein
alone or as part of another group denote optionally substituted,
fully saturated or unsaturated, monocyclic or bicyclic, aromatic or
non-aromatic groups having at least one heteroatom in at least one
ring, and preferably 5 or 6 atoms in each ring. The heterocyclo
group preferably has 1 or 2 oxygen atoms and/or 1 to 4 nitrogen
atoms in the ring, and is bonded to the remainder of the molecule
through a carbon or heteroatom. Exemplary heterocyclo groups
include heteroaromatics as described above. Exemplary substituents
include one or more of the following groups: hydrocarbyl,
substituted hydrocarbyl, alkyl, alkoxy, acyl, acyloxy, alkenyl,
alkenoxy, aryl, aryloxy, amino, amido, acetal, carbamyl,
carbocyclo, cyano, ester, ether, halogen, heterocyclo, hydroxy,
keto, ketal, phospho, nitro, and thio.
[0143] The terms "hydrocarbon" and "hydrocarbyl" as used herein
describe organic compounds or radicals consisting exclusively of
the elements carbon and hydrogen. These moieties include alkyl,
alkenyl, alkynyl, and aryl moieties. These moieties also include
alkyl, alkenyl, alkynyl, and aryl moieties substituted with other
aliphatic or cyclic hydrocarbon groups, such as alkaryl, alkenaryl
and alkynaryl. Unless otherwise indicated, these moieties
preferably comprise 1 to 20 carbon atoms.
[0144] The term "protecting group" as used herein denotes a group
capable of protecting a particular moiety, wherein the protecting
group may be removed, subsequent to the reaction for which the
protection is employed, without disturbing the remainder of the
molecule. Where the moiety is an oxygen atom (and hence, forming a
protected hydroxy), exemplary protecting groups include ethers
(e.g., allyl, triphenylmethyl (trityl or Tr), p-methoxybenzyl
(PMB), p-methoxyphenyl (PMP)), acetals (e.g., methoxymethyl (MOM),
.beta.-methoxyethoxymethyl (MEM), tetrahydropyranyl (THP), ethoxy
ethyl (EE), methylthiomethyl (MTM), 2-methoxy-2-propyl (MOP),
2-trimethylsilylethoxymethyl (SEM)), esters (e.g., benzoate (Bz),
allyl carbonate, 2,2,2-trichloroethyl carbonate (Troc),
2-trimethylsilylethyl carbonate), silyl ethers (e.g.,
trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl
(TIPS), triphenylsilyl (TPS), t-butyldimethylsilyl (TBDMS),
t-butyldiphenylsilyl (TBDPS) and the like. When the moiety is an
nitrogen atom (and hence, forming a protecting amine) exemplary
protecting groups include benzyl, p-methoxyphenyl (PMP),
3,4-dimethoxybenxyl (PMB)), n-silyl groups, esters (e.g., benzoate
(Bz), carbonyl (e.g. p-methoxybenzyl carbonyl (Moz),
tert-butyloxycarbonyl (BOC), 9-fluorenylmethyloxycarbonyl (FMOC)),
acetyl, carbamates, n-silyl groups and the like. A variety of
protecting groups and the synthesis thereof may be found in
"Protective Groups in Organic Synthesis" by T.W. Greene and P.G.M.
Wuts, John Wiley & Sons, 1999.
[0145] The "substituted hydrocarbyl" moieties described herein are
hydrocarbyl moieties which are substituted with at least one atom
other than carbon, including moieties in which a carbon chain atom
is substituted with a heteroatom such as nitrogen, oxygen, silicon,
phosphorous, boron, or a halogen atom, and moieties in which the
carbon chain comprises additional substituents. These substituents
include alkyl, alkoxy, acyl, acyloxy, alkenyl, alkenoxy, aryl,
aryloxy, amino, amido, acetal, carbamyl, carbocyclo, cyano, ester,
ether, halogen, heterocyclo, hydroxy, keto, ketal, phospho, nitro,
and thio.
[0146] When introducing elements of the present disclosure or the
exemplary embodiments(s) thereof, the articles "a," "an," "the,"
and "said" are intended to mean that there are one or more of the
elements. The terms "comprising," "including," and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[0147] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as is commonly understood by one
of skill in the art to which this disclosure belongs at the time of
filing. If specifically defined, then the definition provided
herein takes precedent over any dictionary or extrinsic definition.
Further, unless otherwise required by context, singular terms shall
include pluralities, and plural terms shall include the singular.
Herein, the use of "or" means "and/or" unless stated otherwise. All
patents and publications referred to herein are incorporated by
reference.
[0148] The following examples are intended to further illustrate
and explain the present disclosure. The disclosure, therefore,
should not be limited to any of the details in these examples.
EXAMPLES
[0149] The following examples are included to demonstrate certain
embodiments of the disclosure. It should be appreciated by those of
skill in the art that the techniques disclosed in the examples
represent techniques discovered by the inventors to function well
in the practice of the disclosure. Those of skill in the art
should, however, in light of the present disclosure, appreciate
that many changes can be made in the specific embodiments that are
disclosed and still obtain a like or similar result without
departing from the spirit and scope of the disclosure, therefore
all matter set forth is to be interpreted as illustrative and not
in a limiting sense.
Example 1
Silicon-Based Compositions Using Methoxymethylsiloxane and
Butyltitanate
[0150] It was investigated as to how adding an amine-containing
constituent would effect the curing of a methoxymethylsiloxane
resin with an alkyltitanate. To 2 g of methoxymethylsiloxane
(Silres.RTM. siloxane) was added 50 mg butyltitanate (Tyzor.TM.
BTP) and the components were mixed at 25.degree. C. The reaction
mixture was sonicated using a Fisher FS 15 sonicator bath for 1
minute to promote rapid mixing. The reaction mixtures was allowed
to react at 25.degree. C. for 30 minutes before recording the
Fourier transform infrared (FTIR) spectrum. The spectrum of the
neat mixture (with no solvents added) was recorded the using an
atenuated total reflectance (ATR) detection mode. All FTIR spectra
were recorded using a Cary 630 FTIR (ATR) spectrophotometer with an
average of 64 scans at 25.degree. C. under air.
[0151] The reacted mixture was compared with the known Silres.RTM.
siloxane and Tyzor.TM. BTP starting materials. FIG. 3 depicts the
FTIR spectrum and FIG. 4 the reaction mechanism for the
polymerization of a Silres.RTM. siloxane enhanced by Tyzor.TM. BTP.
Based on the proposed reaction mechanism and experimental
observations, the reaction used ambient water for curing, which may
have come from the atmosphere or the Silres.RTM. siloxane itself. A
moisture level varied from batch to batch and decreased with the
age of the Silres.RTM. siloxane was observed. From the FTIR
spectra, the moisture content in Silres.RTM. was estimated to have
increased from about 0.1% to about 0.5% after 2 weeks of storage at
4.degree. C. FIG. 5 depicts a compound resulting from the reaction
of Tyzor.TM. BTP with a Silres.RTM. siloxane, as shown in FIG.
4.
[0152] To 1 g of the reaction mixture of Silres.RTM. siloxane and
Tyzor.TM. BTP described above was added 0.50 g of
N-[3-(trimethoxysilyl)propyl]ethylenediamine. The new reaction
mixture was sonicated using a Fisher FS 15 sonicator bath for 1
minute to promote rapid mixing. The reaction mixture was allowed to
react at 25.degree. C. for 30 minutes before recording the ATR-FTIR
spectrum (64 scans) on the neat mixture without added solvents
(FIG. 6). The lack of N--H stretches in the spectrum indicated that
the aliphatic amines, including both the primary and secondary
amines, reacted with the n-butylate groups of the titanate bridges.
This reaction further induced branching reactions, as shown in
FIGS. 6-8, by reacting with both, the titanium centers and the
silicon centers in the linear silicone segments. The result was
increased crosslinking of the materials.
[0153] In view of the data described above, the Si--O--CH.sub.3
groups reacted with the Ti--O--Ti centers that remained, rendering
the material more reactive. The FTIR spectrum indicated newly
formed Si--N bonds; therefore, the reaction depicted in FIG. 9
resulted in stable coatings. This reaction enhanced the reactivity
of the mixture during the curing process. The reactions of FIGS.
6-8 formed a more closely interwoven network. In addition, the
reaction was pH-dependent and as catalyzed by the presence of
bases, such as N-[3-(trimethoxysilyl)propyl]ethylenediamine.
Therefore, increasing the concentration of
N-[3-(trimethoxysilyl)propylethylenediamine accelerated the
hardening reaction, especially at room temperature. Similar results
were previously obtained using DT-6020 instead of
N-[3-(trimethoxysilyl)propyl]ethylenediamine. With both amines,
room temperature curing was fastest when 33% by weight of either
N-[3-(trimethoxysilyl)propyl]ethylenediamine or DT-6020 were added.
At higher ratios, the coatings become brittle. The mixtures
hardened within 32 minutes for
N-[3-(trimethoxysilyl)propyl]ethylenediamine and within 35 minutes
for DT-6020 at 25.degree. C. under air. In conclusion, and not
wishing to be bound by theory, the amine-containing component
should comprise less than 33% (w/w) of the total composition to
prevent the formation of brittle coatings.
Example 2
Reaction of Silsesquioxane with Butyltitanate
[0154] Next the polymerized product of a silsesquioxane was
compared to the products of methoxymethylsiloxane described above
at Example 1. Methylsilsesquioxane (1 gram) was reacted with
polymeric butyltitanate (100 mg). The reaction mixtures was
sonicated using a Fisher FS 15 sonicator bath for 1 minute to
promote rapid mixing. The reaction mixture was allowed to react at
25.degree. C. for 30 minutes before recording the ATR-FTIR spectrum
(64 scans) the neat mixture without added solvent. The
characteristic FTIR frequency for methylsilsesquioxane (Si--O--Si,
1180 cm.sup.-1) was completely missing from the FTIR spectrum taken
15 minutes after mixing the constituents together at room
temperature (FIG. 10). Curing proceeded for up to about 60
minutes.
[0155] The caged structure of the methylsilsesquioxanes opened to
form Si--O ladder polymers upon reaction with the butyltitanate, as
depicted in FIG. 11. This reaction mechanism explained the observed
formation of extremely thin layers of the polymerized material.
Furthermore, the n-butanol solvent from the butyltitanate was
oxidized to butanal, as indicated by the presence of a carbonyl
group at 1744 cm.sup.-1 in the spectrum. As a result, some Ti(IV)
was reduced to red-colored Ti(III). The titanate reduction,
however, reversibly oxidized in the air and did not interfere with
forming a clear coating layer.
[0156] In conclusion, reaction of methylsilsesquioxane with
butyltitanate led to previously unobserved siloxane latter
structures. Because of subsequent chemistry on the titanium in the
mixture, clear coatings were formed without tinting from the
residual titanium compounds.
Example 3
Attempted Reaction of Silsesquioxane with Butyltitanate in the
Presence of Amines
[0157] Combining the results of Example 1 with Example 2 was
attempted by testing the addition of an amine-containing
constituent into a mixture of methylsilsesquioxane and
butyltitanate. Specifically, the following reactions were
attempted: mixtures of methylsilsesquioxane (1 g) with polymeric
butyltitanate (100 mg) and
N-[3-(trimethoxysilyl)propyl]ethylenediamine (250 mg),
methylsilsesquioxane (1 g) with polymeric butyltitanate (100 mg)
and polethyleneimide (250 mg), and methylsilsesquioxane (1 g) with
polymeric butyltitanate (100 mg) and 1,3-diaminopropane (250 mg).
All mixtures were very brittle after 1 minute of sonication at
25.degree. C. These mixtures did not adhere to glass surfaces, as
simple scratch tests with a spatula have indicated. Without
polymeric butyltitanate, no hardening was observed within 24 hours
after mixing.
[0158] The spectrum of the neat mixture of methylsilsesquioxane (1
g) with polymeric butyltitanate (100 mg) and
N[3-(trimethoxysilyl)propyl]ethylenediamine (250 mg) was recorded
using ATR detection after 60 minutes of reaction at 25.degree. C.
As shown in FIG. 12, the FTIR spectrum had a Si--O--Si vibration at
1185 cm.sup.-1, which was typical for silsesquioxanes even after 24
hours of reaction. Ladder structures were not predominantly formed
from this reaction, as depicted in FIG. 13. The resulting materials
were brittle because stable layers were flat. Flat layers were
formed by partially opening the silsesquioxanes. The silsesquioxane
was not fully opened the amines reacted with the silsesquioxanes
before the polymeric butyltitanate could. Thus, reaction with the
enhancer was essentially blocked by the prior reaction with the
amines. This observation held true for the other amines tested:
DT-6020, polyethyleneimine, and 1,3-diaminopropane. In conclusion,
and not wishing to be bound by theory, the amine-containing
constituents appear to be incompatible with the
methylsilsesquioxane/butyltitanate resin system, preventing the
formation of the siloxane ladder structures observed in their
absence.
Example 4
Reaction of Silsesquioxane with Butyltitanate and
Triethoxysilane
[0159] The addition of a small-molecule silane in the
methylsilsesquioxane/butyltitanate resin system was investigated.
It was hypothesized that the presence of an Si--H bond would
improve properties of the cured coating. Triethoxysilane (TEOS) was
added to a mixture of methylsilsesquioxane/methoxymethylsiloxane,
and polymeric butyltitanate (5% by weight in n-butanol) at a ratio
of 2:8:1 (v/v/v). After about 15 minutes, the mixture provided a
very thin and crystal clear coating, which strongly bonded to
borosilicate glass. Typically, 80 mg spread out over an area of 1
cm.sup.2. All curing experiments were performed at room temperature
(25.degree. C.). Curing could proceed for up to about 60 minutes.
FIG. 15 depicts the FTIR spectrum of the clear coating, which
indicated the presence of a Si--H bond. FIG. 16 depicts the
proposed reaction mechanism resulting in the clear coating.
[0160] Several other ratios of methylsilsesquioxane,
methoxymethylsiloxane, polymeric butyltitanate, and triethoxysilane
were also investigated. These compositions are described below in
Table 1 along with their hardening times at 65.degree. F. and
350.degree. F., as determined by a scratch test. All samples were
prepared in triplicate. The scratch tests were performed in
accordance with ASTM Standard G171 (03) (Standard Test Method for
Scratch Hardness of Materials Using a Diamond Stylus). Linear
scratches were performed and verified by using a Light Microscope
(Fisher).
TABLE-US-00001 TABLE 1 Silicon-based compositions Hardening
Hardening Methysilsesquioxane* Methylmethoxysiloxane Butyltitanate
Triethoxysilane time at 65.degree. F. time at 350.degree. F. 70%
20% 5% 5% 2 h 0.33 h 4% 6% 2.5 h 0.5 h 3% 7% 3 h 1 h 2% 8% 5 h 1.66
h 1% 9% 8 h 3 h 0.1% 9.9% 24 h 6 h 30% 50% 5% 15% 4 h 1 h 4% 16% 5
h 0.92 h 3% 17% 8 h 1.66 h 2% 18% 12 h 2.33 h 1% 19% 15 h 4 h 0.1%
19.9% 24 h 5 h 10% 5% 35% 5 h 0.83 h 4% 36% 7 h 0.75 h 3% 37% 10 h
1.17 h 2% 38% 14 h 2 h 1% 39% 16 h 3.5 h 0.1% 39.9% 23 h 5 h 10% 5%
75% 3.17 h 0.66 h 4% 76% 3.83 h 1 h 3% 77% 4.33 h 1.33 h 2% 78%
4.66 h 1.83 h 1% 79% 5.5 h 2.5 h 0.1% 79.9% 11 h 3 h *All
percentages are based on weight of the component in the total
composition. Times are measured in hours.
[0161] Generally the compositions of Table 1 comprised 10-70% (w/w)
methylsilsesquioxane, 10-50% (w/w) methylmethoxysiloxane, 0.1-5%
(w/w) polymeric butyltitanate, and 10-50% (w/w) triethoxysilane.
These compositions all hardened (cured) in less than 24 hours, and
some in less than 2 hours. Some compositions even hardened in less
than 1 hour. Compositions with components outside these ranges took
longer than 24 hours to harden. Surprisingly, the presence of
triethoxysilane improved coating adhesion, particularly to glass
substrates. In conclusion, and not wishing to be bound by theory,
the presence of an Si--H bond within at least one component of the
silicon-based composition improved the coating's adhesion
property.
Example 5
Reaction of Silsesquioxane with Butyltitanate and
Methylphenylsilicone Resin
[0162] The effect of adding a methylphenylsilicone resin to the
methylsilsesquioxane/butyltitanate resin system was also
investigated. It was hypothesized that the phenyl groups from the
methylphenylsilicone resin would improve properties of the cured
coating. Methylphenylsilicone resin provided by Wacker Silres.TM.
SY 409 (500 mg) was dissolved in xylenes (5 mL) and reacted with
methylsilsesquioxane (1 g) in the presence of polymeric
butyltitanate (100 mg). The reaction mixture was incubated at
150.degree. C. for 30 minutes. The phenyl groups in
methylphenylsilicone resin hardened the material, because the
planar phenyl rings (--C.sub.6H.sub.5) bound to each other through
hydrophobic effects and II-II electron interactions, as shown
below:
##STR00020##
[0163] The FTIR spectrum of the neat mixture (with no solvents
added) was recorded using ATR detection (64 scans) (See FIG. 17).
The FTIR spectrum demonstrated all structural elements that were
components in the reaction scheme shown at FIG. 18, including the
phenyl groups, Si--C--H groups, phenyl-silicon bonds, Si--O--Si
groups, and Si--CH.sub.3 groups. In conclusion, and not wishing to
be bound by theory, this approach led to superior coatings, via
oligosiloxane ladders formed through the controlled ring-opening of
methylsilsesquioxanes enhanced by polymeric butyltitanate in the
presence of a methylphenylsilicone resin.
Example 6
Comparison of Compositions Based on Silsesquioxane and
Butyltitanate and Methylphenylsilicone Resin
[0164] To observe the differences between the silicon-based
compositions described herein and commercially available resin
systems, compositions based on mixtures of silsesquioxanes and
methylmethoxysiloxanes described above in Examples 1-5 to KDT
HTA.RTM. 1500 were compared. The spectrum of the neat mixture (no
solvents added) of KDT HTA.RTM. 1500 was recorded using ATR
detection (64 scans). According to the FTIR spectrum (FIG. 15), the
vinyl groups in KDT HTA.RTM. 1500 partially polymerized during the
synthesis, forming an incomplete carbon backbone. The two different
backbones (--Si--N--Si-- and --CHR--CH.sub.2--) interfered with the
polymer's adhesion of the polymer to the surface. In comparison,
the molecular network formed from silsesquioxane and
methoxymethylsiloxane mixture comprised Si--O--Si bonds, as
depicted in their FTIR spectra. The bond strength of Si--O bond is
798 kJ/mol, but the strength of the Si--N bond is only 439
kJ/mol.
[0165] In conclusion, and not wishing to be bound by theory,
coatings derived from mixtures of silsesquioxane and
methoxymethylsiloxane were stronger and more resistant to
mechanical damage and chemical attack than were silazane-based
coatings, as calculated from the bond strengths present in the
polumerized material. In particular, coatings derived from
silsesquioxane and methoxymethylsiloxane were estimated to be more
resistant against UV irradiation and more stable against oxidation,
compared to polysilazanes, which are known to polymerize under UV
and too slowly oxidize.
Example 7
Reaction of Silsesquioxane, Butyltitanate, and Methylphenylsilicone
with Silicon Compounds
[0166] To produce resins with good solvent resistance at a ambient
curing conditions, additional silicon compounds were investigated
with the mixture of silsesquioxane, butyltitanate, and
methylmethoxysiloxane. Methylsilsesquioxane/methylmethoxysiloxane
resin (Dow Corning CF2403 liquid resin base at 100 parts by
weight), methylphenylsilicone resin (Wacker Silres.TM. SY 409 at 15
parts by weight), triethoxysilane (Wacker TES 28 at 3.2 parts by
weight), and DT-6060 (100 parts by weight) were combined to form a
mixture. DT-6060 comprises about 3% (w/w) polydimethylsiloxane
fluid, about 4% (w/w) polysilane, and about 93% (w/w) isopropyl
acetate/amyl acetate. The methylphenylsilicone resin was included
in the mixture to help prevent cracking in the cured resin.
[0167] This mixture was diluted with either 20 parts by weight of
tert-butyl acetate (TBAc.TM., Lyondell Basell), isopropyl acetate,
or isoalkanes (hydrotreated heavy naphtha, Isopar.TM. G,
ExxonMobil), depending on the desired drying time of the mixture
during curing. Also added to the mixture was a butyltitanate curing
enhancer: 8.2 parts by weight polymeric butyltitanate (Tyzor.TM.
TBP) to 19 parts tert-butyl acetate or isopropyl acetate; 5.7 parts
by weight (5% w/w) monomeric butyltitante (Tyzor.TM. TnBP); or 1.7
parts by weight (0.5 to 2% w/w) monomeric butyltitante. The
polymeric butyltitanate is very viscous and is easier to handled if
thinned with solvent.
[0168] The formulae using 5% (w/w) butyltitanate cured to a solvent
resistant coating at a 250.degree. F. within about one hour under
atmospheric conditions. The formulae using 1% (w/w) butyltitanate
cured gives a good solvent resistance at a 150.degree. F. within
about 2 hours under atmospheric conditions.
[0169] While specific embodiments have been described above with
reference to the disclosed embodiments and examples, such
embodiments are only illustrative and do not limit the scope of the
disclosure. Changes and modifications can be made in accordance
with ordinary skill in the art without departing from the
disclosure in its broader aspects as defined in the following
claims.
* * * * *
References