U.S. patent application number 12/527875 was filed with the patent office on 2010-06-17 for composite article having excellent fire resistance.
Invention is credited to Nathan P. Greer, Yukinari Harimoto, William Robert O'Brien, Bizhong Zhu.
Application Number | 20100146886 12/527875 |
Document ID | / |
Family ID | 39538063 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100146886 |
Kind Code |
A1 |
Zhu; Bizhong ; et
al. |
June 17, 2010 |
Composite Article Having Excellent Fire Resistance
Abstract
A composite article includes a first pane comprising a first
window layer formed from a vitreous material and a reinforced
silicone layer disposed adjacent to and in contact with the first
window layer. The reinforced silicone layer includes a cured
silicone composition and a fiber reinforcement. The composite
article includes a second pane spaced from the first pane to define
a gap therebetween and a frame disposed adjacent to and in contact
with the first pane and the second pane to enclose the gap. The
composite article may be suitable for load-bearing applications
requiring thermal and acoustic insulation.
Inventors: |
Zhu; Bizhong; (Midland,
MI) ; O'Brien; William Robert; (Midland, MI) ;
Harimoto; Yukinari; (Kanagawa, JP) ; Greer; Nathan
P.; (Freeland, MI) |
Correspondence
Address: |
HOWARD & HOWARD ATTORNEYS PLLC
450 West Fourth Street
Royal Oak
MI
48067
US
|
Family ID: |
39538063 |
Appl. No.: |
12/527875 |
Filed: |
February 21, 2008 |
PCT Filed: |
February 21, 2008 |
PCT NO: |
PCT/US08/02292 |
371 Date: |
March 3, 2010 |
Current U.S.
Class: |
52/232 ;
52/786.11 |
Current CPC
Class: |
B32B 17/10853 20130101;
B32B 25/20 20130101; B32B 17/10174 20130101; B32B 17/10798
20130101; B32B 17/10036 20130101; C08J 2483/00 20130101; B32B
17/10935 20130101; B32B 17/10302 20130101; B32B 17/10045 20130101;
B32B 17/10055 20130101; B32B 17/10366 20130101; B32B 17/1055
20130101; B32B 17/10018 20130101; C08J 7/0427 20200101 |
Class at
Publication: |
52/232 ;
52/786.11 |
International
Class: |
E04B 1/94 20060101
E04B001/94; E04C 2/20 20060101 E04C002/20; E04C 2/54 20060101
E04C002/54 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2007 |
US |
60891165 |
Aug 10, 2007 |
US |
60955245 |
Claims
1. A composite article comprising: a first pane comprising: a first
window layer formed from a first vitreous material; and a
reinforced silicone layer disposed adjacent to and in contact with
said first window layer and comprising a cured silicone composition
and a fiber reinforcement; a second pane spaced from said first
pane to define a gap therebetween; a frame disposed adjacent to and
in contact with said first pane and said second pane and enclosing
the gap between said first pane and said second pane.
2. (canceled)
3. (canceled)
4. A composite article as set forth in claim 1 wherein said fiber
reinforcement is impregnated with said cured silicone
composition.
5. A composite article as set forth in claim 1 wherein said cured
silicone composition is further defined as a hydrosilylation-cured
silicone composition comprising the reaction product of: (A) a
silicone resin; and (B) an organosilicon compound having an average
of at least two silicon-bonded hydrogen atoms per molecule in an
amount sufficient to cure said silicone resin; in the presence of
(C) a catalytic amount of a hydrosilylation catalyst.
6. (canceled)
7. A composite article as set forth in claim 1 wherein said cured
silicone composition is further defined as a condensation-cured
silicone composition comprising the reaction product of: (A'') a
silicone resin having at least two of a silicon-bonded hydroxy
group or a hydrolysable group; and optionally, (B') a cross-linking
agent having silicon-bonded hydrolysable groups, optionally, in the
presence of (C') a catalytic amount of a condensation catalyst.
8. (canceled)
9. A composite article as set forth in claim 1 wherein said
condensation-cured silicone composition further includes an
inorganic filler in particulate form.
10. A composite article as set forth in claim 1 wherein said cured
silicone composition is further defined as a free radical-cured
silicone composition.
11. A composite article as set forth in claim 1 wherein said
silicone composition includes at least one functional group prior
to curing for adhering said cured silicone composition to said
first window layer.
12. A composite article as set forth in claim 11 wherein said at
least one functional group is selected from the group of silanol
groups, alkoxy groups, epoxy groups, silicon hydride groups,
acetoxy groups, and combinations thereof.
13. A composite article as set forth in claim 1 further comprising
an adhesive layer disposed between said reinforced silicone layer
and said first window layer.
14. A composite article as set forth in claim 13 wherein said
adhesive layer comprises a silicone-based adhesive.
15. A composite article as set forth in claim 1 wherein the gap has
a width of from about 1 mm to about 30 mm.
16. A composite article as set forth in claim 1 wherein a pressure
inside the gap is less than about 0.1 atm.
17. A composite article as set forth in claim 1 wherein an
insulator is disposed in the gap.
18. (canceled)
19. A composite article as set forth in claim 1 wherein said frame
is formed from an adhesive.
20. A composite article as set forth in claim 1 wherein said frame
is adhered to said first pane and said second pane.
21. A composite article as set forth in claim 1 wherein said first
pane further comprises an additional window layer disposed adjacent
to and in contact with said reinforced silicone layer and opposite
said first window layer.
22. A composite article as set forth in claim 1 wherein said second
pane comprises a second window layer formed from a second vitreous
material and a second silicone layer disposed adjacent to and in
contact with said second window layer.
23. A composite article as set forth in claim 1 further comprising
a third pane comprising a third window layer formed from a third
vitreous material and a third silicone layer and disposed adjacent
to and in contact with said first window layer.
24. A composite article as set forth in claim 1 further comprising
a third pane comprising a third window layer formed from a third
vitreous material and a third silicone layer and spaced from said
first pane and said second pane and defining at least one gap
therebetween.
25. A composite article as set forth in claim 1 wherein said first
vitreous material is selected from the group of polymethyl
methacrylate, polycarbonate, and polysulfone.
26. A composite article as set forth in claim 1 having a fire
rating of at least 30 minutes in accordance with at least one of
ASTM E 119-05a, ASTM E 2010-01, and ASTM E 2074-00.
27. A composite article as set forth in claim 1 further comprising
a low E coating disposed on at least one of said panes.
28. A composite article as set forth in claim 1 further comprising
a low E coating disposed within at least one of said panes.
Description
RELATED APPLICATIONS
[0001] This patent application claims priority to and all
advantages of U.S. Provisional Patent Application Nos. 60/891,165
and 60/955,245, which were filed on Feb. 22, 2007 and Aug. 10,
2007, respectively.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a composite
article that has excellent thermal and acoustic insulation and fire
resistance. More specifically, the present invention relates to a
composite article having a plurality of panes, with at least one of
the panes having a novel reinforced silicone layer, and a gap
defined between the panes.
[0004] 2. Description of the Prior Art
[0005] Insulated windows are known for use in the residential and
commercial construction industries for providing thermal and
acoustic insulation. The insulated windows often include multiple
panes and are often framed to enclose a gap between the panes. The
gap often contains a gas, for example, air, argon, helium, or
nitrogen gas, to provide thermal and acoustic insulation. The gap
may alternatively be vacated to create a vacuum to enhance thermal
and acoustic insulation. Such insulated windows are typically not
fire-proof, however, and often cannot maintain sufficient
structural integrity after failure of the insulated windows under
heat, i.e. after a breach forms in the panes during a fire. The
inability to maintain sufficient structural integrity may result in
collapse of the panes after formation of the breach, which is
undesirable.
[0006] Fire-proof windows are known for use in the residential,
commercial, and industrial construction industries, as well as the
consumer appliance and automotive industries, for preventing fire,
smoke, or extreme heat from propagating through buildings or to
contain heat or fire within a space, such as in an oven. The
fire-proof windows are typically rated as either 30, 60, 90, or 120
minute fire-proof windows, depending on how long it takes to form a
breach in the fire-proof windows when the fire-proof windows are
exposed to a predefined fire condition leading to an exposure
temperature of 843.degree. C. after 30 minutes, 926.degree. C.
after 60 minutes, 1010.degree. C. after 120 minutes, and
1093.degree. C. after 240 minutes from startup. For example, a
breach forms in a 30 minute rated fire-proof window when the window
is exposed to the above predefined fire condition for a period of
over 30 minutes, but less than 60 minutes. The specific fire-proof
rating required of the fire-proof windows depends upon the
application and cost considerations, since fire-proof windows with
longer fire-proof ratings are typically more costly than fire-proof
windows having shorter fire-proof ratings.
[0007] Much work has been done to develop fire-proof windows that
have sufficient fire-proof ratings. The fire-proof windows are
typically formed from a series of layers, including conventional
glass layers and a layer that provides the fire resistance to the
fire-proof windows. Many different materials have been used to form
the layer that provides the fire resistance; however, many of the
materials used to form the layer that provides the fire resistance
have shortcomings. For example, when carbon-based materials,
especially primarily carbon-based materials having more than 50
parts by weight carbon, based on the total weight of all molecules
in the material, are used to form the layer that provides the fire
resistance, the materials will eventually emit excessive amounts of
smoke and toxic gases.
[0008] Other non-carbon based materials that will not emit as much
smoke and toxic gases, as compared to when primarily carbon-based
materials are used, have also been used for the layer that provides
the fire resistance. For example, inorganic silicon-based materials
have been used in the layer that provides the fire resistance in
the fire-proof windows. Specific examples of inorganic
silicon-based materials that have been used to form the layer that
provides fire resistance in the fire-proof windows include alkali
metal polysilicate hydrate, as disclosed in U.S. Pat. No. 6,159,606
to Gelderie et al., a composition obtained through hydrolysis and
condensation of silicates, as disclosed in U.S. Pat. No. 5,716,424
to Mennig et al., and a silicone elastomer, as disclosed in German
Patent Application No. 2826261. Although the inorganic
silicon-based materials will char, the inorganic silicon-based
materials produce less smoke and toxic gas, as compared to
primarily carbon-based materials. However, existing fire-proof
windows including layers formed from the silicon-based materials
are extremely labor intensive to fabricate, heavy, and sometimes
insufficiently able to maintain structural integrity upon failure
under heat. More specifically, once the breach forms in the
fire-proof windows due to heat, the fire-proof windows are prone to
mechanical failure. Similar deficiencies exist for other
applications where fire protective or resistant transparent
articles are used. Examples include fire rated doors and curtain
walls.
[0009] Due to the deficiencies of the existing windows, including
insulating windows, it would be advantageous to provide a composite
article having excellent thermal and acoustic insulation and fire
resistance that is lighter in weight and also maintains excellent
structural integrity even after failure of the composite article
under heat, i.e., after a breach forms in the composite article,
and that also will not emit as much smoke and toxic gases as
composite articles including primarily carbon-based materials.
SUMMARY OF THE INVENTION AND ADVANTAGES
[0010] The subject invention provides a composite article
comprising a first pane comprising a first window layer formed from
a vitreous material and a reinforced silicone layer. The silicone
layer is disposed adjacent to and in contact with the first window
layer. The reinforced silicone layer includes a cured silicone
composition and a fiber reinforcement. A second pane is spaced from
the first pane to define a gap therebetween. A frame is disposed
adjacent to and in contact with the first pane and the second pane.
The frame encloses the gap between the first pane and the second
pane.
[0011] Due to the presence of the gap between the first pane and
the second pane, the composite article exhibits excellent thermal
and acoustic insulation. Further, due to the presence of the cured
silicone composition in the reinforced silicone layer, the
composite article exhibits excellent fire resistance and will not
emit as much smoke and toxic gases as composite articles including
primarily carbon-based materials. The gap may also aid in the
excellent fire resistance of the composite article by slowing a
progression of heat through the panes of the composite article.
Further still, due to the presence of the fiber reinforcement in
the reinforced silicone layer, the composite article maintains
excellent structural integrity and the panes resist collapse even
after a breach is formed through the panes due to heat. As such,
the composite articles of the subject invention may be suitable for
load-bearing applications requiring thermal and acoustic
insulation, in addition to excellent fire resistance, that are not
possible with the composite articles of the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Other advantages of the present invention will be readily
appreciated, as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings wherein:
[0013] FIG. 1 is a cross-sectional side view of a composite article
of the present invention,
[0014] FIG. 1-A is a cross-sectional side view of a central bore of
the composite article of the present invention,
[0015] FIG. 2 is a cross-sectional side view of a first pane of the
composite article of the present invention,
[0016] FIG. 3 is a cross-sectional side view of another embodiment
of the present invention,
[0017] FIG. 4 is a cross-sectional side view of another embodiment
of the present invention,
[0018] FIG. 5 is a cross-sectional side view of another embodiment
of the present invention,
[0019] FIG. 6 is a cross-sectional side view of another embodiment
of the present invention,
[0020] FIG. 7 is a cross-sectional side view of another embodiment
of the present invention,
[0021] FIG. 8 is a cross-sectional side view of another embodiment
of the present invention,
[0022] FIG. 9 is a cross-sectional side view of another embodiment
of the present invention, and
[0023] FIG. 10 is a cross-sectional side view of another embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Referring to the Figures, wherein like numerals indicate
corresponding parts throughout the several views, a composite
article is shown generally at 10 in FIG. 1. The composite article
10 has excellent thermal and acoustic insulation and excellent fire
resistance and is useful in the residential, commercial, and
industrial construction industries, as well as the consumer
appliance and automotive industries, for preventing fire, smoke, or
extreme heat from propagating through buildings or to contain heat
or fire within a space, such as in an oven. The composite article
10 of the present invention may also be suitable for load-bearing
applications requiring thermal and acoustic insulation, as will be
appreciated with reference to the further description of the
composite article 10 below.
[0025] The composite article 10 includes a first pane 12 that
comprises a first window layer 14 formed from a first vitreous
material. The first window layer 14 typically has high transparency
of at least 80%; however, it is to be appreciated that window
layers having less than 80% transparency may also be suitable for
purposes of the present invention. The first window layer 14
provides wear and scratch-resistance that is typical of
conventional windows.
[0026] The first vitreous material that forms the first window
layer 14 is further defined as any material that is commonly used
to form windows. Specific examples of suitable first vitreous
materials that may be used to form the first window layer 14
include common silica-based glass or a carbon-based polymer. One
specific example of a common silica-based glass is soda-lime-silica
glass. Specific examples of carbon-based polymers that are suitable
for forming the first window layer 14 include, but are not limited
to, polymethyl methacrylate (PMMA), polycarbonate, and
polysulfone.
[0027] The first window layer 14 may be formed through any method
as known in the art for forming window layers. Typically, the first
window layer 14 is float glass, which is formed through a float
process. The glass may be annealed, heat strengthened, or
chemically or heat tempered by methods that are known in the art.
It is to be appreciated that any type of glass formed through any
known process is suitable for purposes of the present
invention.
[0028] The first window layer 14 typically has a thickness of from
about 0.002 to about 1 inch, typically about 0.125 inch. The
specific thickness of the first window layer 14 is dependent on the
specific application for which the composite article 10 is
intended. For example, for load bearing applications or
applications in which the composite article 10 can preferably
withstand significant blunt force, the first window layer 14 may
have a greater thickness than it would for decorative applications.
However, it is to be appreciated that the composite article 10 of
the present invention is not limited to use in load bearing
applications.
[0029] The first pane 12 further comprises a reinforced silicone
layer 16. The reinforced silicone layer 16 is disposed adjacent to
and in contact with the first window layer 14. The reinforced
silicone layer 16 provides the excellent fire resistance to the
composite article 10, as described in further detail below. The
reinforced silicone layer 16 comprises a cured silicone composition
and a fiber reinforcement. Typically, the fiber reinforcement is
impregnated with the cured silicone composition, i.e., the
reinforced silicone layer 16 is a single layer including the fiber
reinforcement and the cured silicone composition. The reinforced
silicone layer 16 typically has less than 50 parts by weight
carbon, more typically less than 35 parts by weight carbon, based
on the total weight of the reinforced silicone layer 16 in order to
ensure that the reinforced silicone layer 16 will emit sufficiently
low levels of smoke and toxic gases during burning. The reinforced
silicone layer 16 is disposed adjacent to and in contact with the
first window layer 14. Methods of attaching the reinforced silicone
layer 16 and the first window layer 14 are described in further
detail below.
[0030] In one embodiment, the cured silicone composition is further
defined as a hydrosilylation-cured silicone composition. The
hydrosilylation-cured silicone composition comprises the reaction
product of (A) a silicone resin and (B) an organosilicon compound
having an average of at least two silicon-bonded hydrogen atoms per
molecule in an amount sufficient to cure the silicone resin, in the
presence of (C) a catalytic amount of a hydrosilylation catalyst.
Any hydrosilylation-cured silicone compositions that are known in
the art may be suitable for purposes of the present invention;
however, some hydrosilylation-cured silicone compositions are more
suitable than others. More specifically, some silicone resins (A)
are more suitable than others.
[0031] The silicone resin (A) typically has silicon-bonded alkenyl
groups or silicon-bonded hydrogen atoms. The silicone resin (A) is
typically a copolymer including R.sup.2SiO.sub.3/2 units, i.e., T
units, and/or SiO.sub.4/2 units, i.e., Q units, in combination with
R.sup.1R.sup.2.sub.2SiO.sub.1/2 units, i.e., M units, and/or
R.sub.2.sup.2SiO.sub.2/2 units, i.e., D units, wherein R.sup.1 is a
C.sub.1 to C.sub.10 hydrocarbyl group or a C.sub.1 to C.sub.10
halogen-substituted hydrocarbyl group, both free of aliphatic
unsaturation, and R.sup.2 is R.sup.1, an alkenyl group, or
hydrogen. For example, the silicone resin (A) can be a DT resin, an
MT resin, an MDT resin, a DTQ resin, and MTQ resin, and MDTQ resin,
a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ
resin. As used herein, the term "free of aliphatic unsaturation"
means the hydrocarbyl or halogen-substituted hydrocarbyl group does
not contain an aliphatic carbon-carbon double bond or carbon-carbon
triple bond.
[0032] The C.sub.1 to C.sub.10 hydrocarbyl group and C.sub.1 to
C.sub.10 halogen-substituted hydrocarbyl group represented by
R.sup.1 more typically have from 1 to 6 carbon atoms. Acyclic
hydrocarbyl and halogen-substituted hydrocarbyl groups containing
at least 3 carbon atoms can have a branched or unbranched
structure. Examples of hydrocarbyl groups represented by R.sup.1
include, but are not limited to, alkyl groups, such as methyl,
ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl,
2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl,
1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl,
2,2-dimethylpropyl, hexyl, heptyl, octyl, nonyl, and decyl;
cycloalkyl groups, such as cyclopentyl, cyclohexyl, and
methylcyclohexyl; aryl groups, such as phenyl and naphthyl; alkaryl
groups, such as tolyl and xylyl; and aralkyl groups, such as benzyl
and phenethyl. Examples of halogen-substituted hydrocarbyl groups
represented by R.sup.1 include, but are not limited to
3,3,3-trifluoropropyl, 3-chloropropyl, chlorophenyl,
dichlorophenyl, 2,2,2-trifluoroethyl, 2,2,3,3-tetrafluoropropyl,
and 2,2,3,3,4,4,5,5-octafluoropentyl.
[0033] The alkenyl groups represented by R.sup.2, which may be the
same or different within the silicone resin (A), typically have
from 2 to about 10 carbon atoms, alternatively from 2 to 6 carbon
atoms, and are exemplified by, but not limited to, vinyl, allyl,
butenyl, hexenyl, and octenyl. In one embodiment, R.sup.2 is
predominantly the alkenyl group. In this embodiment, typically at
least 50 mol %, alternatively at least 65 mol %, alternatively at
least 80 mol %, of the groups represented by R.sup.2 in the
silicone resin are alkenyl groups. As used herein, the mol % of
alkenyl groups in R.sup.2 is defined as a ratio of the number of
moles of silicon-bonded alkenyl groups in the silicone resin to the
total number of moles of the R.sup.2 groups in the resin,
multiplied by 100. In another embodiment, R.sup.2 is predominantly
hydrogen. In this embodiment, typically at least 50 mol %,
alternatively at least 65 mol %, alternatively at least 80 mol %,
of the groups represented by R.sup.2 in the silicone resin are
hydrogen. The mol % of hydrogen in R.sup.2 is defined as a ratio of
the number of moles of silicon-bonded hydrogen in the silicone
resin to the total number of moles of the R.sup.2 groups in the
resin, multiplied by 100.
[0034] According to a first embodiment, the silicone resin (A) has
the formula:
(R.sup.1R.sup.2.sub.2SiO.sub.1/2).sub.w(R.sup.2.sub.2SiO.sub.2/2).sub.x(-
R.sup.2SiO.sub.3/2).sub.y(SiO.sub.4/2).sub.z (1)
wherein R.sup.1 and R.sup.2 are as described and exemplified above,
w, x, y, and z are mole fractions. The silicone resin (A)
represented by formula (I) has an average of at least two
silicon-bonded alkenyl groups per molecule. More specifically, the
subscript w typically has a value of from 0 to 0.9, alternatively
from 0.02 to 0.75, alternatively from 0.05 to 0.3. The subscript x
typically has a value of from 0 to 0.9, alternatively from 0 to
0.45, alternatively from 0 to 0.25. The subscript y typically has a
value of from 0 to 0.99, alternatively from 0.25 to 0.8,
alternatively from 0.5 to 0.8. The subscript z typically has a
value of from 0 to 0.85, alternatively from 0 to 0.25,
alternatively from 0 to 0.15. Also, the ratio y+z/(w+x+y+z) is
typically from 0.1 to 0.99, alternatively from 0.5 to 0.95,
alternatively from 0.65 to 0.9. Further, the ratio w+x/(w+x+y+z) is
typically from 0.01 to 0.90, alternatively from 0.05 to 0.5,
alternatively from 0.1 to 0.35.
[0035] When R.sup.2 is predominantly the alkenyl group, specific
examples of silicone resins (A) represented by formula (I) above
include, but are not limited to, resins having the following
formulae:
(Vi.sub.2MeSiO.sub.1/2).sub.0.25(PhSiO.sub.3/2).sub.0.75,
(ViMe.sub.2SiO.sub.1/2).sub.0.25(PhSiO.sub.3/2).sub.0.75,
(ViMe.sub.2SiO.sub.1/2).sub.0.25(MeSiO.sub.3/2).sub.0.25(PhSiO.sub.3/2).-
sub.0.50,
(ViMe.sub.2SiO.sub.1/2).sub.0.15(PhSiO.sub.3/2).sub.0.75(SiO.sub.4/2).su-
b.0.1 and
(Vi.sub.2MeSiO.sub.1/2).sub.0.15(ViMe.sub.2SiO.sub.1/2).sub.0.1(PhSiO.su-
b.3/2).sub.0.75,
wherein Me is methyl, Vi is vinyl, Ph is phenyl, and the numerical
subscripts outside the parenthesis denote mole fractions
corresponding to either w, x, y, or z as described above for
formula (I). The sequence of units in the preceding formulae is not
to be viewed in any way as limiting to the scope of the
invention.
[0036] When R.sup.2 is predominantly hydrogen, specific examples of
silicone resins (A) represented by formula (I) above include, but
are not limited to, resins having the following formulae:
(HMe.sub.2SiO.sub.1/2).sub.0.25(PhSiO.sub.3/2).sub.0.75,
(HMeSiO.sub.2/2).sub.0.3(PhSiO.sub.3/2).sub.0.6(MeSiO.sub.3/2).sub.0.1,
and
(Me.sub.3SiO.sub.1/2(H.sub.2SiO.sub.2/2).sub.0.1(MeSiO.sub.3/2(PhSiO-
.sub.3/2).sub.0.4,
wherein Me is methyl, Ph is phenyl, and the numerical subscripts
outside the parenthesis denote mole fractions. The sequence of
units in the preceding formulae is not to be viewed in any way as
limiting to the scope of the invention.
[0037] The silicone resin (A) represented by formula (I) typically
has a number-average molecular weight (M.sub.n) of from 500 to
50,000, alternatively from 500 to 10,000, alternatively 1,000 to
3,000, where the molecular weight is determined by gel permeation
chromatography employing a low angle laser light scattering
detector, or a refractive index detector and silicone resin (MQ)
standards.
[0038] The viscosity of the silicone resin (A) represented by
formula (I) at 25.degree. C. is typically from 0.01 to 100,000 Pas,
alternatively from 0.1 to 10,000 Pas, alternatively from 1 to 100
Pas.
[0039] The silicone resin (A) represented by formula (I) typically
includes less than 10% (w/w), alternatively less than 5% (w/w),
alternatively less than 2% (w/w), of silicon-bonded hydroxy groups,
as determined by .sup.29Si NMR.
[0040] Methods of preparing silicone resins (A) represented by
formula (I) are well known in the art; many of these resins are
commercially available. Silicone resins (A) represented by formula
(I) are typically prepared by cohydrolyzing the appropriate mixture
of chlorosilane precursors in an organic solvent, such as toluene.
For example, a silicone resin (A) including
R.sup.1R.sup.2.sub.2SiO.sub.1/2 units and R.sup.2SiO.sub.3/2 units
can be prepared by cohydrolyzing a first compound having the
formula R.sup.1R.sup.2.sub.2SiCl and a second compound having the
formula R.sup.2SiCl.sub.3 in toluene, where R.sup.1 and R.sup.2 are
as defined and exemplified above, to form aqueous hydrochloric acid
and the silicone resin (A), which is a hydrolyzate of the first and
second compounds. The aqueous hydrochloric acid and the silicone
resin (A) are separated, the silicone resin (A) is washed with
water to remove residual acid, and the silicone resin (A) is heated
in the presence of a mild condensation catalyst to "body" the
silicone resin (A) to a desired viscosity, as known in the art.
[0041] If desired, the silicone resin (A) can be further treated
with a condensation catalyst in an organic solvent to reduce the
content of silicon-bonded hydroxy groups. Alternatively, first or
second compounds containing hydrolysable groups other than chloro,
such Br, --I, --OCH.sub.3, --OC(O)CH.sub.3, --N(CH.sub.3).sub.2,
NHCOCH.sub.3, and --SCH.sub.3, can be cohydrolyzed to form the
silicone resin (A). The properties of the silicone resin (A) depend
on the types of first and second compounds, the mole ratio of first
and second compounds, the degree of condensation, and the
processing conditions.
[0042] The organosilicon compound (B) has an average of at least
two silicon-bonded hydrogen atoms per molecule, alternatively at
least three silicon-bonded hydrogen atoms per molecule. It is
generally understood that cross-linking occurs when the sum of the
average number of alkenyl groups per molecule in the silicone resin
(A) and the average number of silicon-bonded hydrogen atoms per
molecule in the organosilicon compound (B) is greater than four.
Prior to curing, the organosilicon compound (B) is present in an
amount sufficient to cure the silicone resin (A).
[0043] The organosilicon compound (B) may be further defined as an
organohydrogensilane, an organohydrogensiloxane, or a combination
thereof. The structure of the organosilicon compound (B) can be
linear, branched, cyclic, or resinous. In acyclic polysilanes and
polysiloxanes, the silicon-bonded hydrogen atoms can be located at
terminal, pendant, or at both terminal and pendant positions.
Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon
atoms, alternatively from 3 to 10 silicon atoms, alternatively from
3 to 4 silicon atoms.
[0044] The organohydrogensilane can be a monosilane, disilane,
trisilane, or polysilane. When R.sup.2 is predominantly the alkenyl
group, specific examples of organohydrogensilanes that are suitable
for purposes of the present invention include, but are not limited
to, diphenylsilane, 2-chloroethylsilane,
bis[(p-dimethylsilyl)phenyl]ether, 1,4-dimethyldisilylethane,
1,3,5-tris(dimethylsilyl)benzene, 1,3,5-trimethyl-1,3,5-trisilane,
poly(methylsilylene)phenylene, and poly(methylsilylene)methylene.
When R.sup.2 is predominantly hydrogen, specific examples of
organohydrogensilanes that are suitable for purposes of the present
invention include, but are not limited to, silanes having the
following formulae:
Vi.sub.4Si, PhSiVi.sub.3, MeSiVi.sub.3, PhMeSiVi.sub.2,
Ph.sub.2SiVi.sub.2, and PhSi(CH.sub.2CH.dbd.CH.sub.2).sub.3,
wherein Me is methyl, Ph is phenyl, and Vi is vinyl.
[0045] The organohydrogensilane can also have the formula:
HR.sup.1.sub.2S.sup.1--R.sup.3--SiR.sup.1.sub.2H (II)
wherein R.sup.1 is as defined and exemplified above and R.sup.3 is
a hydrocarbylene group free of aliphatic unsaturation having a
formula selected from the following structures:
##STR00001##
wherein g is from 1 to 6.
[0046] Specific examples of organohydrogensilanes having the
formula (II), wherein R.sup.1 and R.sup.3 are as described and
exemplified above include, but are not limited to,
organohydrogensilanes having a formula selected from the following
structures:
##STR00002##
[0047] Methods of preparing the organohydrogensilanes are known in
the art. For example, organohydrogensilanes can be prepared by
reaction of Grignard reagents with alkyl or aryl halides. In
particular, organohydrogensilanes having the formula
HR.sup.1.sub.2S.sup.1--R.sup.3--SiR.sup.1.sub.2H can be prepared by
treating an aryl dihalide having the formula R.sup.3X.sub.2 with
magnesium in ether to produce the corresponding Grignard reagent
and then treating the Grignard reagent with a chlorosilane having
the formula HR.sup.1.sub.2SiCl, where R.sup.1 and R.sup.3 are as
described and exemplified above.
[0048] The organohydrogensiloxane can be a disiloxane, trisiloxane,
or polysiloxane. Examples of organosiloxanes suitable for use as
the organosilicon compound (B) when R.sup.2 is predominantly
hydrogen include, but are not limited to, siloxanes having the
following formulae:
PhSi(OSiMe.sub.2H).sub.3, Si(OSiMe.sub.2H).sub.4,
MeSi(OSiMe.sub.2H).sub.3, and Ph.sub.2Si(OSiMe.sub.2H).sub.2,
wherein Me is methyl, and Ph is phenyl.
[0049] Specific examples of organohydrogensiloxanes that are
suitable for purposes of the present invention when R.sup.2 is
predominantly alkenyl group including, but are not limited to,
1,1,3,3-tetramethyldisiloxane, 1,1,3,3-tetraphenyldisiloxane,
phenyltris(dimethylsiloxy)silane, 1,3,5-trimethylcyclotrisiloxane,
a trimethylsiloxy-terminated poly(methylhydrogensiloxane), a
trimethylsiloxy-terminated
poly(dimethylsiloxane/methylhydrogensiloxane), a
dimethylhydrogensiloxy-terminated poly(methylhydrogensiloxane), and
a resin including HMe.sub.2SiO.sub.1/2 units, Me.sub.3SiO.sub.1/2
units, and SiO.sub.4/2 units, wherein Me is methyl.
[0050] The organohydrogensiloxane can also be an
organohydrogenpolysiloxane resin. The organohydrogenpolysiloxane
resin is typically a copolymer including R.sup.4SiO.sub.3/2 units,
i.e., T units, and/or SiO.sub.4/2 units, i.e., Q units, in
combination with R.sup.1R.sup.4.sub.2SiO.sub.1/2 units, i.e., M
units, and/or R.sup.4.sub.2SiO.sub.2/2 units, i.e., D units,
wherein R.sup.1 is as described and exemplified above. For example,
the organohydrogenpolysiloxane resin can be a DT resin, an MT
resin, an MDT resin, a DTQ resin, and MTQ resin, and MDTQ resin, a
DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ
resin.
[0051] The group represented by R.sup.4 is either R.sup.1 or an
organosilylalkyl group having at least one silicon-bonded hydrogen
atom. Examples of organosilylalkyl groups represented by R.sup.4
include, but are not limited to, groups having a formula selected
from the following structures:
##STR00003##
--CH.sub.2CH.sub.2SiMe.sub.2H,
--CH--.sub.2CH.sub.2SiMe.sub.2C.sub.nH.sub.2nSiMe.sub.2H,
--CH.sub.2CH.sub.2SiMe.sub.2C.sub.nH.sub.2nSiMePhH,
--CH.sub.2CH.sub.2SiMePhH, --CH.sub.2CH.sub.2SiPh.sub.2H,
--CH.sub.2CH.sub.2SiMePhC.sub.nH.sub.2nSiPh.sub.2H,
--CH.sub.2CH.sub.2SiMePhC.sub.nH.sub.2nSiMe.sub.2H,
--CH.sub.2CH.sub.2SiMePhOSiMePhH, and
--CH.sub.2CH.sub.2SiMePhOSiPh(OSiMePhH).sub.2, wherein Me is
methyl, Ph is phenyl, and the subscript n has a value of from 2 to
10. Typically, at least 50 mol %, alternatively at least 65 mol %,
alternatively at least 80 mol % of the groups represented by
R.sup.4 in the organohydrogenpolysiloxane resin are
organosilylalkyl groups having at least one silicon-bonded hydrogen
atom. As used herein, the mol % of organosilylalkyl groups in
R.sup.4 is defined as a ratio of the number of moles of
silicon-bonded organosilylalkyl groups in the silicone resin (A) to
the total number of moles of the R.sup.4 groups in the resin,
multiplied by 100.
[0052] The organohydrogenpolysiloxane resin typically has the
formula:
(R.sup.1R.sup.4.sub.2SiO.sub.1/2).sub.w(R.sup.4.sub.2SiO.sub.2/2).sub.x(-
R.sup.4SiO.sub.3/2).sub.y(SiO.sub.4/2).sub.z
wherein R.sup.1, R.sup.4, w, x, y, and z are each as defined and
exemplified above.
[0053] Specific examples of organohydrogenpolysiloxane resins
represent by formula (III) above include, but are not limited to,
resins having the following formulae:
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.12(PhSiO.sub.3/2).sub.0.88,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.17(PhSiO.sub.3/2).sub.0.83,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.17(MeSiO.sub.3/2).sub.0.17(PhSiO.sub.3/2).sub.0.66,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.15(PhSiO.sub.3/2).sub.0.75(SiO.sub.4/2).sub.0.10, and
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.08((HMe.sub.2SiCl.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2)Me.sub.2-
SiO.sub.1/2).sub.0.06(PhSiO.sub.3/2).sub.0.86,
wherein Me is methyl, Ph is phenyl, C.sub.6H.sub.4 denotes a
para-phenylene group, and the numerical subscripts outside the
parenthesis denote mole fractions. The sequence of units in the
preceding formulae is not to be viewed in any way as limiting to
the scope of the invention.
[0054] Specific examples of organohydrogenpolysiloxane resins
include, but are not limited to, resins having the following
formulae:
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.12(PhSiO.sub.3/2).sub.0.88,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.17(PhSiO.sub.3/2).sub.0.83,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.17(MeSiO.sub.3/2).sub.0.17(PhSiO.sub.3/2).sub.0.66,
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.15(PhSiO.sub.3/2).sub.0.75(SiO.sub.4/2).sub.0.10, and
((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2).sub.2MeSiO.sub.1/-
2).sub.0.08((HMe.sub.2SiC.sub.6H.sub.4SiMe.sub.2CH.sub.2CH.sub.2)
Me.sub.2SiO.sub.1/2).sub.0.06(PhSiO.sub.3/2).sub.0.86,
where Me is methyl, Ph is phenyl, C.sub.6H.sub.4 denotes a
para-phenylene group, and the numerical subscripts outside the
parenthesis denote mole fractions. The sequence of units in the
preceding formulae is not to be viewed in any way as limiting to
the scope of the invention.
[0055] The organohydrogenpolysiloxane resin having the formula
(III) can be prepared by reacting a reaction mixture including (a)
a silicone resin having the formula
(R.sup.1R.sup.2.sub.2SiO.sub.1/2).sub.w(R.sup.2.sub.2SiO.sub.2/2).sub.x(R-
.sup.2SiO.sub.3/2).sub.y(SiO.sub.4/2).sub.z represented by formula
(I) above and an organosilicon compound (b) having an average of
from two to four silicon-bonded hydrogen atoms per molecule and a
molecular weight less than 1,000, in the presence of (c) a
hydrosilylation catalyst and, optionally, (d) an organic solvent,
wherein R.sup.1, R.sup.2, w, x, y, and z are each as defined and
exemplified above, provided the silicone resin (a) has an average
of at least two silicon-bonded alkenyl groups per molecule, and the
mole ratio of silicon-bonded hydrogen atoms in (b) to alkenyl
groups in (a) is from 1.5 to 5. Silicone resin (a) can be the same
as or different than the specific silicone resin used as component
(A) to form the hydrosilylation-cured silicone composition.
[0056] As set forth above, organosilicon compound (b) has an
average of from two to four silicon-bonded hydrogen atoms per
molecule. Alternatively, the organosilicon compound (b) has an
average of from two to three silicon-bonded hydrogen atoms per
molecule. As also set forth above, the organosilicon compound (b)
typically has a molecular weight less than 1,000, alternatively
less than 750, alternatively less than 500. The organosilicon
compound (b) further includes silicon-bonded organic groups that
may be selected from the group of hydrocarbyl groups and
halogen-substituted hydrocarbyl groups, both free of aliphatic
unsaturation, which are as described and exemplified above for
R.sup.1.
[0057] Organosilicon compound (b) can be an organohydrogensilane or
an organohydrogensiloxane, each of which are defined and
exemplified in detail above. Organosilicon compound (b) can further
be a single organosilicon compound or a mixture comprising two or
more different organosilicon compounds, each as described above.
For example, organosilicon compound (B) can be a single
organohydrogensilane, a mixture of two different
organohydrogensilanes, a single organohydrogensiloxane, a mixture
of two different organohydrogensiloxanes, or a mixture of an
organohydrogensilane and an organohydrogensiloxane. The mole ratio
of silicon-bonded hydrogen atoms in organosilicon compound (b) to
alkenyl groups in silicone resin (a) is typically from 1.5 to 5,
alternatively from 1.75 to 3, alternatively from 2 to 2.5.
[0058] Hydrosilylation catalyst (c) can be any of the well-known
hydrosilylation catalysts comprising a platinum group metal (i.e.,
platinum, rhodium, ruthenium, palladium, osmium and iridium) or a
compound containing a platinum group metal. Typically, the platinum
group metal is platinum, based on its high activity in
hydrosilylation reactions.
[0059] Specific hydrosilylation catalysts suitable for (c) include
the complexes of chloroplatinic acid and certain vinyl-containing
organosiloxanes disclosed by Willing in U.S. Pat. No. 3,419,593,
which is hereby incorporated by reference. A catalyst of this type
is the reaction product of chloroplatinic acid and
1,3-diethenyl-1,1,3,3-tetramethyldisiloxane.
[0060] The hydrosilylation catalyst (c) can also be a supported
hydrosilylation catalyst comprising a solid support having a
platinum group metal on the surface thereof. A supported catalyst
can be conveniently separated from the organohydrogenpolysiloxane
resin represented by formula (III), for example, by filtering the
reaction mixture. Examples of supported catalysts include, but are
not limited to, platinum on carbon, palladium on carbon, ruthenium
on carbon, rhodium on carbon, platinum on silica, palladium on
silica, platinum on alumina, palladium on alumina, and ruthenium on
alumina.
[0061] The concentration of hydrosilylation catalyst (c) is
sufficient to catalyze the addition reaction of silicone resin (a)
with organosilicon compound (b). Typically, the concentration of
hydrosilylation catalyst (c) is sufficient to provide from 0.1 to
1000 ppm of a platinum group metal, alternatively from 1 to 500 ppm
of a platinum group metal, alternatively from 5 to 150 ppm of a
platinum group metal, based on the combined weight of silicone
resin (a) and organosilicon compound (b). The rate of reaction is
very slow below 0.1 ppm of platinum group metal. The use of more
than 1000 ppm of platinum group metal results in no appreciable
increase in reaction rate, and is therefore uneconomical.
[0062] Organic solvent (d) is at least one organic solvent. The
organic solvent (d) can be any aprotic or dipolar aprotic organic
solvent that does not react with silicone resin (a), organosilicon
compound (b), or the resulting organohydrogenpolysiloxane resin
under the conditions of the present method, and is miscible with
components (a), (b), and the organohydrogenpolysiloxane resin.
[0063] Examples of organic solvents (d) that are suitable for
purposes of the present invention include, but are not limited to,
saturated aliphatic hydrocarbons such as n-pentane, hexane,
n-heptane, isooctane and dodecane; cycloaliphatic hydrocarbons such
as cyclopentane and cyclohexane; aromatic hydrocarbons such as
benzene, toluene, xylene and mesitylene; cyclic ethers such as
tetrahydrofuran (THF) and dioxane; ketones such as methyl isobutyl
ketone (MIBK); halogenated alkanes such as trichloroethane; and
halogenated aromatic hydrocarbons such as bromobenzene and
chlorobenzene. Organic solvent (d) can be a single organic solvent
or a mixture comprising two or more different organic solvents,
each as described above. The concentration of organic solvent (d)
is typically from 0 to 99% (w/w), alternatively from 30 to 80%
(w/w), alternatively from 45 to 60% (w/w), based on the total
weight of the reaction mixture.
[0064] The reaction to form the organohydrogenpolysiloxane resin
represented by formula (III) can be carried out in any standard
reactor suitable for hydrosilylation reactions. Suitable reactors
include glass and Teflon-lined glass reactors. Typically, the
reactor is equipped with a means of agitation, such as stirring.
Also, typically, the reaction is carried out in an inert
atmosphere, such as nitrogen or argon, in the absence of
moisture.
[0065] The silicone resin (a), organosilicon compound (b),
hydrosilylation catalyst (c), and, optionally, organic solvent (d),
can be combined in any order. Typically, organosilicon compound (b)
and hydrosilylation catalyst (c) are combined before the
introduction of the silicone resin (a) and, optionally, organic
solvent (d). The reaction is typically carried out at a temperature
of from 0 to 150.degree. C., alternatively from room temperature
(.about.23.+-.2.degree. C.) to 115.degree. C. When the temperature
is less than 0.degree. C., the rate of reaction is typically very
slow. The reaction time depends on several factors, such as the
structures of the silicone resin (a) and the organosilicon compound
(b), and the temperature. The time of reaction is typically from 1
to 24 h at a temperature of from room temperature
(.about.23.+-.2.degree. C.) to 150.degree. C. The optimum reaction
time can be determined by routine experimentation.
[0066] The organohydrogenpolysiloxane resin represented by formula
(III) can be used without isolation or purification or the
organohydrogenpolysiloxane resin can be separated from most of the
organic solvent (d) by conventional methods of evaporation. For
example, the reaction mixture can be heated under reduced pressure.
Moreover, when the hydrosilylation catalyst (c) is a supported
catalyst, as described above, the organohydrogenpolysiloxane resin
can be readily separated from the hydrosilylation catalyst (c) by
filtering the reaction mixture. However, the hydrosilylation
catalyst (c) may remain mixed with the organohydrogenpolysiloxane
resin and be used as hydrosilylation catalyst (c).
[0067] The organosilicon compound (B) can be a single organosilicon
compound or a mixture comprising two or more different
organosilicon compounds, each as described above. For example, the
organosilicon compound (B) can be a single organohydrogensilane, a
mixture of two different organohydrogensilanes, a single
organohydrogensiloxane, a mixture of two different
organohydrogensiloxanes, or a mixture of an organohydrogensilane
and an organohydrogensiloxane. In particular, the organosilicon
compound (B) can be a mixture comprising the
organohydrogenpolysiloxane resin having the formula (III) in an
amount of at least 0.5% (w/w), alternatively at least 50% (w/w),
alternatively at least 75% (w/w), based on the total weight of the
organosilicon compound (B), with the organosilicon compound (B)
further comprising an organohydrogensilane and/or
organohydrogensiloxane, the latter different from the
organohydrogenpolysiloxane resin.
[0068] The concentration of organosilicon compound (B) is
sufficient to cure (cross-link) the silicone resin (A). The exact
amount of organosilicon compound (B) depends on the desired extent
of cure. The concentration of organosilicon compound (B) is
typically sufficient to provide from 0.4 to 2 moles of
silicon-bonded hydrogen atoms, alternatively from 0.8 to 1.5 moles
of silicon-bonded hydrogen atoms, alternatively from 0.9 to 1.1
moles of silicon-bonded hydrogen atoms, per mole of alkenyl groups
in silicone resin (A).
[0069] Hydrosilylation catalyst (C) includes at least one
hydrosilylation catalyst that promotes the reaction between
silicone resin (A) and organosilicon compound (B). In one
embodiment, the hydrosilylation catalyst (C) may be the same as the
hydrosilylation catalyst (c) described above for producing the
organohydrogenpolysiloxane resin. In addition, the hydrosilylation
catalyst (C) can also be a microencapsulated platinum group
metal-containing catalyst comprising a platinum group metal
encapsulated in a thermoplastic resin. Microencapsulated
hydrosilylation catalysts and methods of preparing them are well
known in the art, as exemplified in U.S. Pat. No. 4,766,176 and the
references cited therein, and U.S. Pat. No. 5,017,654. The
hydrosilylation catalyst (C) can be a single catalyst or a mixture
comprising two or more different catalysts that differ in at least
one property, such as structure, form, platinum group metal,
complexing ligand, and thermoplastic resin.
[0070] In another embodiment, the hydrosilylation catalyst (C) may
be at least one photoactivated hydrosilylation catalyst. The
photoactivated hydrosilylation catalyst can be any hydrosilylation
catalyst capable of catalyzing the hydrosilylation of the silicone
resin (A) and the organosilicon compound (B) upon exposure to
radiation having a wavelength of from 150 to 800 nm. The
photoactivated hydrosilylation catalyst can be any of the
well-known hydrosilylation catalysts comprising a platinum group
metal or a compound containing a platinum group metal. The platinum
group metals include platinum, rhodium, ruthenium, palladium,
osmium and iridium. Typically, the platinum group metal is
platinum, based on its high activity in hydrosilylation reactions.
The suitability of particular photoactivated hydrosilylation
catalyst for use in the silicone composition of the present
invention can be readily determined by routine experimentation.
[0071] Specific examples of photoactivated hydrosilylation
catalysts suitable for purposes of the present invention include,
but are not limited to, platinum(II) .beta.-diketonate complexes
such as platinum(II) bis(2,4-pentanedioate), platinum(II)
bis(2,4-hexanedioate), platinum(II) bis(2,4-heptanedioate),
platinum(II) bis(1-phenyl-1,3-butanedioate, platinum(II)
bis(1,3-diphenyl-1,3-propanedioate), platinum(II)
bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedioate);
(.eta.-cyclopentadienyl)trialkylplatinum complexes, such as
(Cp)trimethylplatinum, (Cp)ethyldimethylplatinum,
(Cp)triethylplatinum, (chloro-Cp)trimethylplatinum, and
(trimethylsilyl-Cp)trimethylplatinum, where Cp represents
cyclopentadienyl; triazene oxide-transition metal complexes, such
as Pt[C.sub.6H.sub.5NNNOCH.sub.3].sub.4,
Pt[p-CN--C.sub.6H.sub.4NNNOC.sub.6H.sub.11].sub.4,
Pt[p-H.sub.3COC.sub.6H.sub.4NNNOC.sub.6H.sub.11].sub.4,
Pt[p-CH.sub.3(CH.sub.2).sub.x--C.sub.6H.sub.4NNNOCH.sub.3].sub.4,
1,5-cyclooctadiene.Pt[p-CN--C.sub.6H.sub.4NNNOC.sub.6H.sub.11].sub.2,
1,5-cyclooctadiene.Pt[p-CH.sub.3O--C.sub.6H.sub.4NNNOCH.sub.3].sub.2,
[(C.sub.6H.sub.5).sub.3P].sub.3Rh[p-CN--C.sub.6H.sub.4NNNOC.sub.6H.sub.11-
], and
Pd[p-CH.sub.3(CH.sub.2).sub.x--C.sub.6H.sub.4NNNOCH.sub.3].sub.2,
where x is 1, 3, 5, 11, or 17; (.eta.-diolefin)(.nu.-aryl)platinum
complexes, such as
(.eta..sup.4-1,5-cyclooctadienyl)diphenylplatinum,
.eta..sup.4-1,3,5,7-cyclooctatetraenyl)diphenylplatinum,
(.eta..sup.4-2,5-norboradienyl)diphenylplatinum,
(.eta..sup.4-1,5-cyclooctadienyl)bis-(4-dimethylaminophenyl)platinum,
(.eta..sup.4-1,5-cyclooctadienyl)bis-(4-acetylphenyl)platinum, and
(.eta..sup.4-1,5-cyclooctadienyl)bis-(4-trifluormethylphenyl)platinum.
Typically, the photoactivated hydrosilylation catalyst is a Pt(II)
.beta.-diketonate complex and more typically the catalyst is
platinum(II) bis(2,4-pentanedioate). The hydrosilylation catalyst
(C) can be a single photoactivated hydrosilylation catalyst or a
mixture comprising two or more different photoactivated
hydrosilylation catalysts.
[0072] Methods of preparing photoactivated hydrosilylation
catalysts are well known in the art. For example, methods of
preparing platinum(II) .beta.-diketonates are reported by Guo et
al. (Chemistry of Materials, 1998, 10, 531-536). Methods of
preparing (.eta.-cyclopentadienyl)-trialkylplatinum complexes and
are disclosed in U.S. Pat. No. 4,510,094. Methods of preparing
triazene oxide-transition metal complexes are disclosed in U.S.
Pat. No. 5,496,961. And, methods of preparing
(.eta.-diolefin)(.sigma.-aryl)platinum complexes are taught in U.S.
Pat. No. 4,530,879.
[0073] The concentration of the hydrosilylation catalyst (C) is
sufficient to catalyze the addition reaction of the silicone resin
(A) and the organosilicon compound (B). The concentration of the
hydrosilylation catalyst (C) is sufficient to provide typically
from 0.1 to 1000 ppm of platinum group metal, alternatively from
0.5 to 100 ppm of platinum group metal, alternatively from 1 to 25
ppm of platinum group metal, based on the combined weight of the
silicone resin (A) and the organosilicon compound (B).
[0074] Optionally, the hydrosilylation-cured silicone composition
further includes (D) a silicone rubber having a formula selected
from the group of:
R.sup.1R.sup.2.sub.2SiO(R.sup.2.sub.2SiO).sub.aSiR.sup.2.sub.2R.sup.1;
and (i)
R.sup.5R.sup.1.sub.2SiO(R.sup.1R.sup.5SiO).sub.bSiR.sup.1.sub.2R.sup.5;
(ii)
wherein R.sup.1 and R.sup.2 are as defined and exemplified above,
R.sup.5 is R.sup.1 or --H, subscripts a and b each have a value of
from 1 to 4, from 2 to 4 or from 2 to 3, and w, x, y, and z are
also as defined and exemplified above, provided the silicone resin
and the silicone rubber (D)(i) each have an average of at least two
silicon-bonded alkenyl groups per molecule, the silicone rubber
(D)(ii) has an average of at least two silicon-bonded hydrogen
atoms per molecule, and the mole ratio of silicon-bonded alkenyl
groups or silicon-bonded hydrogen atoms in the silicone rubber (D)
to silicon-bonded alkenyl groups in the silicone resin (A) is from
0.01 to 0.5.
[0075] Specific examples of silicone rubbers suitable for use as
component (D)(i) include, but are not limited to, silicone rubbers
having the following formulae:
ViMe.sub.2SiO(Me.sub.2SiO).sub.aSiMe.sub.2Vi,
ViMe.sub.2SiO(Ph.sub.2SiO).sub.aSiMe.sub.2Vi, and
ViMe.sub.2SiO(PhMeSiO).sub.aSiMe.sub.2Vi,
wherein Me is methyl, Ph is phenyl, Vi is vinyl, and the subscript
a has a value of from 1 to 4. Silicone rubber (D)(i) can be a
single silicone rubber or a mixture comprising two or more
different silicone rubbers that each satisfy the formula for
(D)(i).
[0076] Specific examples of silicone rubbers suitable for use as
silicone rubber (D)(ii) include, but are not limited to, silicone
rubbers having the following formulae:
HMe.sub.2SiO(Me.sub.2SiO).sub.bSiMe.sub.2H,
HMe.sub.2SiO(Ph.sub.2SiO).sub.bSiMe.sub.2H,
HMe.sub.2SiO(PhMeSiO).sub.b
SiMe.sub.2H, and
HMe.sub.2SiO(Ph.sub.2SiO).sub.2(Me.sub.2SiO).sub.2SiMe.sub.2H,
wherein Me is methyl, Ph is phenyl, and the subscript b has a value
of from 1 to 4. Component (D)(ii) can be a single silicone rubber
or a mixture comprising two or more different silicone rubbers that
each satisfy the formula for (D)(ii).
[0077] The mole ratio of silicon-bonded alkenyl groups or
silicon-bonded hydrogen atoms in the silicone rubber (D) to
silicon-bonded alkenyl groups in the silicone resin (A) is
typically from 0.01 to 0.5, alternatively from 0.05 to 0.4,
alternatively from 0.1 to 0.3.
[0078] When the silicone rubber (D) is (D)(i), the concentration of
the organosilicon compound (B) is such that the ratio of the number
of moles of silicon-bonded hydrogen atoms in the organosilicon
compound (B) to the sum of the number of moles of silicon-bonded
alkenyl groups in the silicone resin (A) and the silicone rubber
(D)(i) is typically from 0.4 to 2, alternatively from 0.8 to 1.5,
alternatively from 0.9 to 1.1. Furthermore, when the silicone
rubber (D) is (D)(ii), the concentration of the organosilicon
compound (B) is such that the ratio of the sum of the number of
moles of silicon-bonded hydrogen atoms in the organosilicon
compound (B) and the silicone rubber (D)(ii) to the number of moles
of silicon-bonded alkenyl groups in the silicone resin (A) is
typically from 0.4 to 2, alternatively from 0.8 to 1.5,
alternatively from 0.9 to 1.1.
[0079] Methods of preparing silicone rubbers containing
silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms are
well known in the art; many of these compounds are commercially
available.
[0080] In another embodiment of the present invention, the
hydrosilylation-cured silicone composition comprises the reaction
product of (A') a rubber-modified silicone resin and the
organosilicon compound (B), in the presence of (C) the catalytic
amount of the hydrosilylation catalyst. The rubber-modified
silicone resin (A') may be prepared by reacting the silicone resin
(A) and a silicone rubber (D)(iii) having the following
formulae:
R.sup.5R.sup.1.sub.2SiO(R.sup.1R.sup.5SiO).sub.cSiR.sup.1.sub.2R.sup.5,
R.sup.1R.sup.2.sub.2SiO(R.sup.2.sub.2SiO).sub.dSiR.sup.2.sub.2R.sup.1,
wherein R.sup.1 and R.sup.5 are as defined and exemplified above
and c and d each have a value of from 4 to 1000, alternatively from
10 to 500, alternatively from 10 to 50, in the presence of the
hydrosilylation catalyst (c) and, optionally, an organic solvent,
provided the silicone resin (A) has an average of at least two
silicon-bonded alkenyl groups per molecule, the silicone rubber
(D)(iii) has an average of at least two silicon-bonded hydrogen
atoms per molecule, and the mole ratio of silicon-bonded hydrogen
atoms in the silicone rubber (D)(iii) to silicon-bonded alkenyl
groups in silicone resin (A) is from 0.01 to 0.5. When organic
solvent is present, the rubber-modified silicone resin (A') is
miscible in the organic solvent and does not form a precipitate or
suspension.
[0081] The silicone resin (A), silicone rubber (D)(iii),
hydrosilylation catalyst (c), and organic solvent can be combined
in any order. Typically, the silicone resin (A), silicone rubber
(D)(iii), and organic solvent are combined before the introduction
of the hydrosilylation catalyst (c).
[0082] The reaction is typically carried out at a temperature of
from room temperature (.about.23.+-.2.degree. C.) to 150.degree.
C., alternatively from room temperature to 100.degree. C. The
reaction time depends on several factors, including the structures
of the silicone resin (A) and the silicone rubber (D)(iii) and the
temperature. The components are typically allowed to react for a
period of time sufficient to complete the hydrosilylation reaction.
This means the components are typically allowed to react until at
least 95 mol %, alternatively at least 98 mol %, alternatively at
least 99 mol %, of the silicon-bonded hydrogen atoms originally
present in the silicone rubber (D)(iii) have been consumed in the
hydrosilylation reaction, as determined by FTIR spectrometry. The
time of reaction is typically from 0.5 to 24 h at a temperature of
from room temperature (.about.23.+-.2.degree. C.) to 100.degree. C.
The optimum reaction time can be determined by routine
experimentation.
[0083] The mole ratio of silicon-bonded hydrogen atoms in the
silicone rubber (D)(iii) to silicon-bonded alkenyl groups in the
silicone resin (A) is typically from 0.01 to 0.5, alternatively
from 0.05 to 0.4, alternatively from 0.1 to 0.3.
[0084] The concentration of the hydrosilylation catalyst (c) is
sufficient to catalyze the addition reaction of the silicone resin
(A) with the silicone rubber (D)(iii). Typically, the concentration
of the hydrosilylation catalyst (c) is sufficient to provide from
0.1 to 1000 ppm of a platinum group metal, based on the combined
weight of the resin and the rubber.
[0085] The concentration of the organic solvent is typically from 0
to 95% (w/w), alternatively from 10 to 75% (w/w), alternatively
from 40 to 60% (w/w), based on the total weight of the reaction
mixture.
[0086] The rubber-modified silicone resin (A') can be used without
isolation or purification or the rubber-modified silicone resin
(A') can be separated from most of the solvent by conventional
methods of evaporation. For example, the reaction mixture can be
heated under reduced pressure. Moreover, when the hydrosilylation
catalyst (c) is a supported catalyst, described above, the
rubber-modified silicone resin (A') can be readily separated from
the hydrosilylation catalyst (c) by filtering the reaction mixture.
However, when the rubber-modified silicone resin (A') is not
separated from the hydrosilylation catalyst (c) used to prepare the
rubber-modified silicone resin (A'), the hydrosilylation catalyst
(c) may be used as the hydrosilylation catalyst (C).
[0087] The hydrosilylation-cured silicone composition of the
present invention can comprise additional ingredients, as known in
the art. Examples of additional ingredients include, but are not
limited to, hydrosilylation catalyst inhibitors, such as
3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne,
3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol,
2-phenyl-3-butyn-2-ol, vinylcyclosiloxanes, and triphenylphosphine;
adhesion promoters, such as the adhesion promoters taught in U.S.
Pat. Nos. 4,087,585 and 5,194,649; dyes; pigments; anti-oxidants;
heat stabilizers; UV stabilizers; flame retardants; flow control
additives; and diluents, such as organic solvents and reactive
diluents.
[0088] As an alternative to the hydrosilylation-cured silicone
composition, condensation-cured silicone compositions are also
suitable for the silicone composition of the present invention.
[0089] The condensation-cured silicone composition typically
includes the reaction product of a silicone resin (A'') having
silicon-bonded hydroxy or hydrolysable groups and, optionally, a
cross-linking agent (B') having silicon-bonded hydrolysable groups,
and optionally a condensation catalyst (C'). The silicone resin
(A'') is typically a copolymer containing T and/or Q siloxane units
in combination with M and/or D siloxane units.
[0090] The condensation-cured silicone composition may be any
condensation-cured silicone composition as known in the art.
However, certain condensation-cured silicone compositions are
particularly suitable for purposes of the present invention.
According to one embodiment, the silicone resin (A'') has the
formula:
(R.sup.1R.sup.6.sub.2SiO.sub.1/2).sub.w'(R.sup.6.sub.2SiO.sub.2/2).sub.x-
'(R.sup.6SiO.sub.3/2).sub.y'(SiO.sub.4/2).sub.z' (IV)
wherein R.sup.1 is as defined and exemplified above, R.sup.6 is
R.sup.1, --H, --OH, or a hydrolysable group, and w' is from 0 to
0.8, alternatively from 0.02 to 0.75, and alternatively from 0.05
to 0.3, x' is from 0 to 0.95, alternatively from 0.05 to 0.8, and
alternatively from 0.1 to 0.3, y' is from 0 to 1, alternatively
from 0.25 to 0.8, and alternatively from 0.5 to 0.8, and z' is from
0 to 0.99, alternatively from 0.2 to 0.8, and alternatively from
0.4 to 0.6, and the silicone resin (A'') has an average of at least
two silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable
groups per molecule. As used herein the term "hydrolysable group"
means the silicon-bonded group reacts with water in the absence of
a catalyst at any temperature from room temperature
(.about.23.+-.2.degree. C.) to 100.degree. C. within several
minutes, for example thirty minutes, to form a silanol (Si--OH)
group. Examples of hydrolysable groups represented by R.sup.6
include, but are not limited to, --Cl, --Br, --OR.sup.7,
--OCH.sub.2CH.sub.2OR.sup.7, CH.sub.3C(.dbd.O)O--,
Et(Me)C.dbd.N--O--, CH.sub.3C(.dbd.O)N(CH.sub.3)--, and
--ONH.sub.2, wherein R.sup.7 is C.sub.1 to C.sub.8 hydrocarbyl or
C.sub.1 to C.sub.8 halogen-substituted hydrocarbyl.
[0091] The hydrocarbyl and halogen-substituted hydrocarbyl groups
represented by R.sup.7 typically have from 1 to 8 carbon atoms,
alternatively from 3 to 6 carbon atoms. Acyclic hydrocarbyl and
halogen-substituted hydrocarbyl groups containing at least 3 carbon
atoms can have a branched or unbranched structure. Examples of
hydrocarbyl groups represented by R.sup.7 include, but are not
limited to, unbranched and branched alkyl, such as methyl, ethyl,
propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl,
1,1-dimethylethyl, pentyl, 1-methylbutyl, 1-ethylpropyl,
2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl,
2,2-dimethylpropyl, hexyl, heptyl, and octyl; cycloalkyl, such as
cyclopentyl, cyclohexyl, and methylcyclohexyl; phenyl; alkaryl,
such as tolyl and xylyl; aralkyl, such as benzyl and phenethyl;
alkenyl, such as vinyl, allyl, and propenyl; arylalkenyl, such as
styryl; and alkynyl, such as ethynyl and propynyl. Examples of
halogen-substituted hydrocarbyl groups represented by R.sup.7
include, but are not limited to, 3,3,3-trifluoropropyl,
3-chloropropyl, chlorophenyl, and dichlorophenyl.
[0092] Typically, at least 5 mol %, alternatively at least 15 mol
%, alternatively at least 30 mol % of the groups R.sup.6 in the
silicone resin are hydrogen, hydroxy, or a hydrolysable group. As
used herein, the mol % of groups in R.sup.6 is defined as a ratio
of the number of moles of silicon-bonded groups in the silicone
resin (A'') to the total number of moles of the R.sup.6 groups in
the silicone resin (A''), multiplied by 100.
[0093] Specific examples of cured silicone resins formed from
silicone resin (A'') include, but are not limited to, cured
silicone resins having the following formulae:
(MeSiO.sub.3/2).sub.n, (PhSiO.sub.3/2).sub.n,
(Me.sub.3SiO.sub.1/2).sub.0.8(SiO.sub.4/2).sub.0.2,
(MeSiO.sub.3/2).sub.0.67(PhSiO.sub.3/2).sub.0.33,
(MeSiO.sub.3/2).sub.0.45(PhSiO.sub.3/2).sub.0.40(Ph.sub.2SiO.sub.2/2).su-
b.0.1(PhMeSiO.sub.2/2).sub.0.05,
(PhSiO.sub.3/2).sub.0.4(MeSiO.sub.3/2).sub.0.45(PhSiO.sub.3/2).sub.0.1(P-
hMeSiO.sub.2/2).sub.0.05, and
(PhSiO.sub.3/2).sub.0.4(MeSiO.sub.3/2).sub.0.4(MeSiO.sub.3/2).sub.0.1(Ph-
MeSiO.sub.2/2).sub.0.5,
wherein Me is methyl, Ph is phenyl, the numerical subscripts
outside the parenthesis denote mole fractions, and the subscript n
has a value such that the silicone resin has a number-average
molecular weight of from 500 to 50,000. The sequence of units in
the preceding formulae is not to be viewed in any way as limiting
to the scope of the invention.
[0094] As set forth above, the silicone resin (A'') represented by
formula (IV) typically has a number-average molecular weight
(M.sub.n) of from 500 to 50,000. Alternatively, the silicone resin
(A'') may have a M.sub.n of at least 300, alternatively 1,000 to
3,000, where the molecular weight is determined by gel permeation
chromatography employing a low angle laser light scattering
detector, or a refractive index detector and silicone resin (MQ)
standards.
[0095] The viscosity of the silicone resin (A'') at 25.degree. C.
is typically from 0.01 Pas to solid, alternatively from 0.1 to
100,000 Pas, alternatively from 1 to 1,000 Pas.
[0096] Methods of preparing silicone resins (A'') represented by
formula (IV) are well known in the art; many of these resins are
commercially available. Silicone resins (A'') represented by
formula (IV) are typically prepared by cohydrolyzing the
appropriate mixture of chlorosilane precursors in an organic
solvent, such as toluene. For example, a silicone resin including
R.sup.1R.sup.6.sub.2SiO.sub.1/2 units and R.sup.6SiO.sub.3/2 units
can be prepared by cohydrolyzing a first compound having the
formula R.sup.1R.sup.6.sub.2SiCl and a second compound having the
formula R.sup.6SiCl.sub.3 in toluene, where R.sup.1 and R.sup.6 are
as defined and exemplified above. The cohydrolyzing process is
described above in terms of the hydrosilylation-cured silicone
composition. The cohydrolyzed reactants can be further "bodied" to
a desired extent to control the amount of crosslinkable groups and
viscosity.
[0097] The Q units in formula (IV) can be in the form of discrete
particles in the silicone resin (A''). The particle size is
typically from 1 nm to 20 Examples of these particles include, but
not limited to, silica (SiO.sub.4/2) particles of 15 nm in
diameter.
[0098] The condensation cured silicone composition can further
contain inorganic fillers such as silica, alumina, calcium
carbonate, and mica.
[0099] In another embodiment, the condensation-cured silicone
composition comprises the reaction product of a rubber-modified
silicone resin (A''') and the other optional components. The
rubber-modified silicone resin (A''') may be prepared by reacting
an organosilicon compound selected from (i) a silicone resin having
the formula
(R.sup.1R.sup.6.sub.2SiO.sub.1/2).sub.w(R.sup.6.sub.2SiO.sub.2/2).sub.x(R-
.sup.6SiO.sub.3/2).sub.y(SiO.sub.4/2).sub.z and (ii) hydrolysable
precursors of (i), and (iii) a silicone rubber having the formula
R.sup.8.sub.3SiO(R.sup.1R.sup.8SiO).sub.mSiR.sup.8.sub.3 in the
presence of water, (iv) a condensation catalyst, and (v) an organic
solvent, wherein R.sup.1 and R.sup.6 are as defined and exemplified
above, R.sup.8 is R.sup.1 or a hydrolysable group, m is from 2 to
1,000, alternatively from 4 to 500, alternatively from 8 to 400,
and w, x, y, and z are as defined and exemplified above, and
silicone resin (i) has an average of at least two silicon-bonded
hydroxy or hydrolysable groups per molecule, the silicone rubber
(iii) has an average of at least two silicon-bonded hydrolysable
groups per molecule, and the mole ratio of silicon-bonded
hydrolysable groups in the silicone rubber (iii) to silicon-bonded
hydroxy or hydrolysable groups in the silicone resin (i) is from
0.01 to 1.5, alternatively from 0.05 to 0.8, alternatively from 0.2
to 0.5.
[0100] Typically at least 5 mol %, alternatively at least 15 mol %,
alternatively at least 30 mol % of the groups R.sup.6 in the
silicone resin (i) are hydroxy or hydrolysable groups.
[0101] The silicone resin (i) typically has a number-average
molecular weight (M.sub.n) of at least 300, alternatively from 500
to 10,000, alternatively 1,000 to 3,000, where the molecular weight
is determined by gel permeation chromatography employing a low
angle laser light scattering detector, or a refractive index
detector and silicone resin (MQ) standards.
[0102] Specific examples of cured silicone resins formed from
silicone resin (i) include, but are not limited to, cured silicone
resins having the following formulae:
(MeSiO.sub.3/2).sub.n, (PhSiO.sub.3/2).sub.n,
(PhSiO.sub.3/2).sub.0.4(MeSiO.sub.3/2).sub.0.45(PhSiO.sub.3/2).sub.0.1(P-
hMeSiO.sub.2/2).sub.0.05, and
(PhSiO.sub.3/2).sub.0.3(SiO.sub.4/2).sub.0.1(Me.sub.2SiO.sub.2/2).sub.0.-
2(Ph.sub.2SiO.sub.2/2).sub.0.4,
where Me is methyl, Ph is phenyl, the numerical subscripts outside
the parenthesis denote mole fractions, and the subscript n has a
value such that the silicone resin has a number-average molecular
weight of from 500 to 50,000. The sequence of units in the
preceding formulae is not to be viewed in any way as limiting to
the scope of the invention. Silicone resin (i) can be a single
silicone resin or a mixture comprising two or more different
silicone resins, each having the specified formula.
[0103] As used herein, the term "hydrolysable precursors" refers to
silanes having hydrolysable groups that are suitable for use as
starting materials (precursors) for preparation of the silicone
resin (i). The hydrolysable precursors (ii) can be represented by
the formulae R.sup.1R.sup.8.sub.2SiX, R.sup.8.sub.2SiX.sub.2,
R.sup.8SiX.sub.3, and SiX.sub.4, wherein R.sup.1, R.sup.8, and X
are as defined and exemplified above.
[0104] Specific examples of hydrolysable precursors (ii) include,
but are not limited to, silanes having the formulae:
Me.sub.2ViSiCl, Me.sub.3SiCl, MeSi(OEt).sub.3, PhSiCl.sub.3,
MeSiCl.sub.3, Me.sub.2SiCl.sub.2, PhMeSiCl.sub.2,
SiCl.sub.4, Ph.sub.2SiCl.sub.2, PhSi(OMe).sub.3, MeSi(OMe).sub.3,
PhMeSi(OMe).sub.2, and Si(OEt).sub.4,
wherein Me is methyl, Et is ethyl, and Ph is phenyl.
[0105] Specific examples of silicone rubbers (iii) include, but are
not limited to, silicone rubbers having the following formulae:
(EtO).sub.3SiO(Me.sub.2SiO).sub.55Si(OEt).sub.3,
(EtO).sub.3SiO(Me.sub.2SiO).sub.16Si(OEt).sub.3,
(EtO).sub.3SiO(Me.sub.2SiO).sub.386Si(OEt).sub.3, and
(EtO).sub.2MeSiO(PhMeSiO).sub.10SiMe(OEt).sub.2,
wherein Me is methyl and Et is ethyl.
[0106] The reaction is typically carried out at a temperature of
from room temperature (.about.23.+-.2.degree. C.) to 180.degree.
C., alternatively from room temperature to 100.degree. C.
[0107] The reaction time depends on several factors, including the
structures of the silicone resin (i) and the silicone rubber (iii),
and the temperature. The components are typically allowed to react
for a period of time sufficient to complete the condensation
reaction. This means the components are allowed to react until at
least 95 mol %, alternatively at least 98 mol %, alternatively at
least 99 mol %, of the silicon-bonded hydrolysable groups
originally present in the silicone rubber (iii) have been consumed
in the condensation reaction, as determined by .sup.29Si NMR
spectrometry. The time of reaction is typically from 1 to 30 h at a
temperature of from room temperature (.about.23.+-.2.degree. C.) to
100.degree. C. The optimum reaction time can be determined by
routine experimentation.
[0108] Suitable condensation catalysts (iv) are described in
further detail below, and suitable organic solvents (v) are
described above in the context of rubber-modified silicone resin
(A') above. The concentration of the condensation catalyst (iv) is
sufficient to catalyze the condensation reaction of the silicone
resin (i) with the silicone rubber (iii). Typically, the
concentration of the condensation catalyst (iv) is from 0.01 to 2%
(w/w), alternatively from 0.01 to 1% (w/w), alternatively from 0.05
to 0.2% (w/w), based on the weight of the silicon resin (i). The
concentration of the organic solvent (v) is typically from 10 to
95% (w/w), alternatively from 20 to 85% (w/w), alternatively from
50 to 80% (w/w), based on the total weight of the reaction
mixture.
[0109] The concentration of water in the reaction mixture depends
on the nature of the groups R.sup.8 in the organosilicon compound
and the nature of the silicon-bonded hydrolysable groups in the
silicone rubber. When the silicone resin (i) contains hydrolysable
groups, the concentration of water is sufficient to effect
hydrolysis of the hydrolysable groups in the silicon resin (i) and
the silicone rubber (iii). For example, the concentration of water
is typically from 0.01 to 3 moles, alternatively from 0.05 to 1
moles, per mole of hydrolysable group in the silicone resin (i) and
the silicone rubber (iii) combined. When the silicone resin (i)
does not contain hydrolysable groups, only a trace amount, e.g.,
100 ppm, of water is required in the reaction mixture. Trace
amounts of water are normally present in the reactants and/or
solvent.
[0110] As set forth above, the condensation-cured silicone
composition can further comprise the reaction product of the
cross-linking agent (B'). The cross-linking agent (B') can have the
formula R.sup.7.sub.qSiX.sub.4-q, wherein R.sup.7 is C.sub.1 to
C.sub.8 hydrocarbyl or C.sub.1 to C.sub.8 halogen-substituted
hydrocarbyl, X is a hydrolysable group, and q is 0 or 1. The
hydrocarbyl and halogen-substituted hydrocarbyl groups represented
by R.sup.7, and the hydrolysable groups represented by X are as
described and exemplified above.
[0111] Specific examples of cross-linking agents (B') include, but
are not limited to, alkoxy silanes such as MeSi(OCH.sub.3).sub.3,
CH.sub.3Si(OCH.sub.2CH.sub.3).sub.3,
CH.sub.3Si(OCH.sub.2CH.sub.2CH.sub.3).sub.3,
CH.sub.3Si[O(OCH.sub.2).sub.3CH.sub.3].sub.3,
CH.sub.3CH.sub.2Si(OCH.sub.2CH.sub.3).sub.3,
C.sub.6H.sub.5Si(OCH.sub.3).sub.3,
C.sub.6H.sub.5CH.sub.2Si(OCH.sub.3).sub.3,
C.sub.6H.sub.5Si(OCH.sub.2CH.sub.3).sub.3,
CH.sub.2.dbd.CHSi(OCH.sub.3).sub.3,
CH.sub.2.dbd.CHCH.sub.2Si(OCH.sub.3).sub.3,
CF.sub.3CH.sub.2CH.sub.2Si(OCH.sub.3).sub.3,
CH.sub.3Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
CF.sub.3CH.sub.2CH.sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
CH.sub.2.dbd.CHSi(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
CH.sub.2.dbd.CHCH.sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
C.sub.6H.sub.5Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
Si(OCH.sub.3).sub.4, Si(OC.sub.2H.sub.5).sub.4, and
Si(OC.sub.3H.sub.7).sub.4; organoacetoxysilanes such as
CH.sub.3Si(OCOCH.sub.3).sub.3,
CH.sub.3CH.sub.2Si(OCOCH.sub.3).sub.3, and
CH.sub.2.dbd.CHSKOCOCH.sub.3).sub.3; organoiminooxysilanes such as
CH.sub.3Si[O--N.dbd.C(CH.sub.3)CH.sub.2CH.sub.3].sub.3,
Si[O--N.dbd.C(CH.sub.3)CH.sub.2CH.sub.3].sub.4, and
CH.sub.2.dbd.CHSi[O--N.dbd.C(CH.sub.3)CH.sub.2CH.sub.3].sub.3;
organoacetamidosilanes such as
CH.sub.3Si[NHC(.dbd.O)CH.sub.3].sub.3 and
C.sub.6H.sub.5Si[NHC(.dbd.O)CH.sub.3].sub.3; amino silanes such as
CH.sub.3Si[NH(s-C.sub.4H.sub.9)].sub.3 and
CH.sub.3Si(NHC.sub.6H.sub.11).sub.3; and organoaminooxysilanes.
[0112] The cross-linking agent (B') can be a single silane or a
mixture of two or more different silanes, each as described above.
Also, methods of preparing tri- and tetra-functional silanes are
well known in the art; many of these silanes are commercially
available.
[0113] When used, the concentration of the cross-linking agent (B')
prior to formation of the condensation-cured silicone composition
is sufficient to cure (cross-link) the condensation-cured silicone
resin. The exact amount of the cross-linking agent (B') depends on
the desired extent of cure, which generally increases as the ratio
of the number of moles of silicon-bonded hydrolysable groups in the
cross-linking agent (B') to the number of moles of silicon-bonded
hydrogen atoms, hydroxy groups, or hydrolysable groups in the
silicone resin (A'') increases. Typically, the concentration of the
cross-linking agent (B') is sufficient to provide from 0.2 to 4
moles of silicon-bonded hydrolysable groups per mole of
silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable
groups in the silicone resin (A''). The optimum amount of the
cross-linking agent (B') can be readily determined by routine
experimentation.
[0114] Condensation catalyst (C') can be any condensation catalyst
typically used to promote condensation of silicon-bonded hydroxy
(silanol) groups to form Si--O--Si linkages. Examples of
condensation catalysts include, but are not limited to, amines; and
complexes of lead, tin, zinc, and iron with carboxylic acids. In
particular, the condensation catalyst (C') can be selected from
tin(II) and tin(IV) compounds such as tin dilaurate, tin dioctoate,
and tetrabutyl tin; and titanium compounds such as titanium
tetrabutoxide.
[0115] When present, the concentration of the condensation catalyst
(C') is typically from 0.1 to 10% (w/w), alternatively from 0.5 to
5% (w/w), alternatively from 1 to 3% (w/w), based on the total
weight of the silicone resin (A'').
[0116] When the condensation-cured silicone composition is formed
in the presence of the condensation catalyst (C'), the
condensation-cured silicone composition is typically formed from a
two-part composition where the silicone resin (A'') and
condensation catalyst (C') are in separate parts.
[0117] The condensation-cured silicone composition of the present
invention can comprise additional ingredients, as known in the art
and as described above for the hydrosilylation-cured silicone
composition.
[0118] In yet another embodiment, the silicone composition may be a
free radical-cured silicone composition. Examples of free
radical-cured silicone compositions include peroxide-cured silicone
compositions, radiation-cured silicone compositions containing a
free radical photoinitiator, and high energy radiation-cured
silicone compositions. Typically, the free radical-cured silicone
composition comprises the reaction product of a silicone resin
(A'''') and, optionally, a cross-linking agent (B'') and/or a free
radical initiator (C'') (e.g., a free radical photoinitiator or
organic peroxide).
[0119] The silicone resin (A'''') can be any silicone resin that
can be cured (i.e., cross-linked) by at least one method selected
from (i) exposing the silicone resin to radiation having a
wavelength of from 150 to 800 nm in the presence of a free radical
photoinitiator, (ii) heating the silicone resin (A'''') in the
presence of an organic peroxide, and (iii) exposing the silicone
resin (A'''') to an electron beam. The silicone resin (A'''') is
typically a copolymer containing T siloxane units and/or Q siloxane
units in combination with M and/or D siloxane units.
[0120] For example, the silicone resin (A'''') may have the
formula:
(R.sup.1R.sup.9.sub.2SiO.sub.1/2).sub.w''(R.sup.9.sub.2SiO.sub.2/2).sub.-
x''(R.sup.9SiO.sub.3/2).sub.y''(SiO.sub.4/2).sub.z'',
wherein R.sup.1 is as defined and exemplified above, R.sup.9 is
R.sup.1, alkenyl, or alkynyl, w'' is from 0 to 0.99, x'' is from 0
to 0.99, y'' is from 0 to 0.99, and z'' is from 0 to 0.85, and
w''+x''+y''+z''=1.
[0121] The alkenyl groups represented by R.sup.9, which may be the
same or different, are as defined and exemplified in the
description of R.sup.2 above.
[0122] The alkynyl groups represented by R.sup.9, which may be the
same or different, typically have from 2 to about 10 carbon atoms,
alternatively from 2 to 6 carbon atoms, and are exemplified by, but
not limited to, ethynyl, propynyl, butynyl, hexynyl, and
octynyl.
[0123] The silicone resin (A'''') typically has a number-average
molecular weight (M.sub.n) of at least 300, alternatively from 500
to 10,000, alternatively 1,000 to 3,000, where the molecular weight
is determined by gel permeation chromatography employing a
refractive index detector and silicone resin (MQ) standards.
[0124] The silicone resin (A'''') can contain less than 10% (w/w),
alternatively less than 5% (w/w), alternatively less than 2% (w/w),
of silicon-bonded hydroxy groups, as determined by .sup.29Si
NMR.
[0125] Specific examples of silicone resins (A'''') that are
suitable for purposes of the present invention include, but are not
limited to, silicone resins having the following formulae:
(Vi.sub.2MeSiO.sub.1/2).sub.0.25(PhSiO.sub.3/2).sub.0.75,
(ViMe.sub.2SiO.sub.1/2).sub.0.25(PhSiO.sub.3/2).sub.0.75,
(ViMe.sub.2SiO.sub.1/2).sub.0.25(MeSiO.sub.3/2).sub.0.25(PhSiO.sub.3/2).-
sub.0.50,
(ViMe.sub.2SiO.sub.1/2).sub.0.15(PhSiO.sub.3/2).sub.0.75(SiO.sub.4/2).su-
b.0.75, and
(Vi.sub.2MeSiO.sub.1/2).sub.0.15(ViMe.sub.2SiO.sub.1/2).sub.0.1(PhSiO.su-
b.3/2).sub.0.75,
wherein Me is methyl, Vi is vinyl, Ph is phenyl, and the numerical
subscripts outside the parenthesis denote mole fractions. The
sequence of units in the preceding formulae is not to be viewed in
any way as limiting to the scope of the invention.
[0126] The free radical-cured silicone composition of the present
method can comprise additional ingredients including, but are not
limited to, silicone rubbers; unsaturated compounds; free radical
initiators; organic solvents; UV stabilizers; sensitizers; dyes;
flame retardants; antioxidants; fillers, such as reinforcing
fillers, extending fillers, and conductive fillers; and adhesion
promoters.
[0127] The free radical-cured silicone composition can further
comprise the reaction product of an unsaturated compound selected
from (i) at least one organosilicon compound having at least one
silicon-bonded alkenyl group per molecule, (ii) at least one
organic compound having at least one aliphatic carbon-carbon double
bond per molecule, and (iii) mixtures comprising (i) and (ii),
wherein the unsaturated compound has a molecular weight less than
500. Alternatively, the unsaturated compound has a molecular weight
less than 400 or less than 300. Also, the unsaturated compound can
have a linear, branched, or cyclic structure.
[0128] The organosilicon compound (i) can be an organosilane or an
organosiloxane. The organosilane can be a monosilane, disilane,
trisilane, or polysilane. Similarly, the organosiloxane can be a
disiloxane, trisiloxane, or polysiloxane. Cyclosilanes and
cyclosiloxanes typically have from 3 to 12 silicon atoms,
alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4
silicon atoms. In acyclic polysilanes and polysiloxanes, the
silicon-bonded alkenyl group(s) can be located at terminal,
pendant, or at both terminal and pendant positions.
[0129] Specific examples of organosilanes include, but are not
limited to, silanes having the following formulae:
Vi.sub.4Si, PhSiVi.sub.3, MeSiVi.sub.3, PhMeSiVi.sub.2,
Ph.sub.2SiVi.sub.2, and PhSi(CH.sub.2CH.dbd.CH.sub.2).sub.3,
wherein Me is methyl, Ph is phenyl, and Vi is vinyl.
[0130] Specific examples of organosiloxanes include, but are not
limited to, siloxanes having the following formulae:
PhSi(OSiMe.sub.2Vi).sub.3, Si(OSiMe.sub.2Vi).sub.4,
MeSi(OSiMe.sub.2Vi).sub.3, and Ph.sub.2Si(OSiMe.sub.2Vi).sub.2,
wherein Me is methyl, Vi is vinyl, and Ph is phenyl.
[0131] The organic compound can be any organic compound containing
at least one aliphatic carbon-carbon double bond per molecule,
provided the compound does not prevent the silicone resin (A'''')
from curing to form a silicone resin film. The organic compound can
be an alkene, a diene, a triene, or a polyene. Further, in acyclic
organic compounds, the carbon-carbon double bond(s) can be located
at terminal, pendant, or at both terminal and pendant
positions.
[0132] The organic compound can contain one or more functional
groups other than the aliphatic carbon-carbon double bond. Examples
of suitable functional groups include, but are not limited to,
--O--, >C.dbd.O, --CHO, --CO.sub.2--, --C.ident.N, --NO.sub.2,
>C.dbd.C<, --C.ident.C--, --F, --Cl, --Br, and --I. The
suitability of a particular unsaturated organic compound for use in
the free-radical cured silicone composition of the present
invention can be readily determined by routine experimentation.
[0133] The organic compound can have a liquid or solid state at
room temperature. Also, the organic compound can be soluble,
partially soluble, or insoluble in the free-radical cured silicone
composition prior to curing. The normal boiling point of the
organic compound, which depends on the molecular weight, structure,
and number and nature of functional groups in the compound, can
vary over a wide range. Typically, the organic compound has a
normal boiling point greater than the cure temperature of the
composition. Otherwise, appreciable amounts of the organic compound
may be removed by volatilization during cure.
[0134] Examples of organic compounds containing aliphatic
carbon-carbon double bonds include, but are not limited to,
1,4-divinylbenzene, 1,3-hexadienylbenzene, and
1,2-diethenylcyclobutane.
[0135] The unsaturated compound can be a single unsaturated
compound or a mixture comprising two or more different unsaturated
compounds, each as described above. For example, the unsaturated
compound can be a single organosilane, a mixture of two different
organosilanes, a single organosiloxane, a mixture of two different
organosiloxanes, a mixture of an organosilane and an
organosiloxane, a single organic compound, a mixture of two
different organic compounds, a mixture of an organosilane and an
organic compound, or a mixture of an organosiloxane and an organic
compound.
[0136] The concentration of the unsaturated compound is typically
from 0 to 70% (w/w), alternatively from 10 to 50% (w/w),
alternatively from 20 to 40% (w/w), based on the total weight of
the free radical-cured silicone composition prior to curing.
[0137] Methods of preparing organosilanes and organosiloxanes
containing silicon-bonded alkenyl groups, and organic compounds
containing aliphatic carbon-carbon double bonds are well known in
the art; many of these compounds are commercially available.
[0138] The free radical initiator is typically a free radical
photoinitiator or an organic peroxide. Further, the free radical
photoinitiator can be any free radical photoinitiator capable of
initiating cure (cross-linking) of the silicone resin upon exposure
to radiation having a wavelength of from 200 to 800 nm.
[0139] Examples of free radical photoinitiators include, but are
not limited to, benzophenone; 4,4'-bis(dimethylamino)benzophenone;
halogenated benzophenones; acetophenone;
.alpha.-hydroxyacetophenone; chloro acetophenones, such as
dichloroacetophenones and trichloroacetophenones;
dialkoxyacetophenones, such as 2,2-diethoxyacetophenone;
.alpha.-hydroxyalkylphenones, such as
2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexyl
phenyl ketone; .alpha.-aminoalkylphenones, such as
2-methyl-4'-(methylthio)-2-morpholiniopropiophenone; benzoin;
benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether,
and benzoin isobutyl ether; benzil ketals, such as
2,2-dimethoxy-2-phenylacetophenone; acylphosphinoxides, such as
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; xanthone
derivatives; thioxanthone derivatives; fluorenone derivatives;
methyl phenyl glyoxylate; acetonaphthone; anthraquinone
derivatives; sulfonyl chlorides of aromatic compounds; and O-acyl
.alpha.-oximinoketones, such as
1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime.
[0140] The free radical photoinitiator can also be a polysilane,
such as the phenylmethylpolysilanes defined by West in U.S. Pat.
No. 4,260,780, the disclosure of which as it relates to the
phenylmethylpolysilanes is hereby incorporated by reference; the
aminated methylpolysilanes defined by Baney et al. in U.S. Pat. No.
4,314,956, the disclosure of which is hereby incorporated by
reference as it relates to aminated methylpolysilanes; the
methylpolysilanes of Peterson et al. in U.S. Pat. No. 4,276,424,
the disclosure of which is hereby incorporated by reference as it
relates to methylpolysilanes; and the polysilastyrene defined by
West et al. in U.S. Pat. No. 4,324,901, the disclosure of which is
hereby incorporated by reference as it relates to
polysilastyrene.
[0141] The free radical photoinitiator can be a single free radical
photoinitiator or a mixture comprising two or more different free
radical photoinitiators. The concentration of the free radical
photoinitiator is typically from 0.1 to 6% (w/w), alternatively
from 1 to 3% (w/w), based on the weight of the silicone resin
(A'''').
[0142] The free radical initiator can also be an organic peroxide.
Examples of organic peroxides include, diaroyl peroxides such as
dibenzoyl peroxide, di-p-chlorobenzoyl peroxide, and
bis-2,4-dichlorobenzoyl peroxide; dialkyl peroxides such as
di-t-butyl peroxide and 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane;
diaralkyl peroxides such as dicumyl peroxide; alkyl aralkyl
peroxides such as t-butyl cumyl peroxide and
1,4-bis(t-butylperoxyisopropyl)benzene; and alkyl aroyl peroxides
such as t-butyl perbenzoate, t-butyl peracetate, and t-butyl
peroctoate.
[0143] The organic peroxide can be a single peroxide or a mixture
comprising two or more different organic peroxides. The
concentration of the organic peroxide is typically from 0.1 to 5%
(w/w), alternatively from 0.2 to 2% (w/w), based on the weight of
the silicone resin (A'''').
[0144] The free radical-cured silicone composition can further be
formed in the presence of at least one organic solvent. The organic
solvent can be any aprotic or dipolar aprotic organic solvent that
does not react with the silicone resin (A'''') or additional
ingredient(s) and is miscible with the silicone resin (A'''').
Examples of organic solvents include, but are not limited to,
saturated aliphatic hydrocarbons such as n-pentane, hexane,
n-heptane, isooctane and dodecane; cycloaliphatic hydrocarbons such
as cyclopentane and cyclohexane; aromatic hydrocarbons such as
benzene, toluene, xylene and mesitylene; cyclic ethers such as
tetrahydrofuran (THF) and dioxane; ketones such as methyl isobutyl
ketone (MIBK); halogenated alkanes such as trichloroethane; and
halogenated aromatic hydrocarbons such as bromobenzene and
chlorobenzene. The organic solvent can be a single organic solvent
or a mixture comprising two or more different organic solvents,
each as described above.
[0145] The concentration of the organic solvent is typically from 0
to 99% (w/w), alternatively from 30 to 80% (w/w), alternatively
from 45 to 60% (w/w), based on the total weight of the free
radical-cured silicone composition prior to curing.
[0146] When the free-radical cured silicone composition described
above is formed from one or more additional ingredients, for
example, a free radical initiator, the free-radical cured silicone
composition may be formed from a one-part composition comprising
the silicone resin (A'''') and optional ingredient(s) in a single
part, or a multi-part composition comprising the components in two
or more parts.
[0147] In addition to the silicone compositions set forth above,
other cured silicone compositions are also suitable for purposes of
the present invention. For example, suitable silicone compositions,
for purposes of the present invention, are disclosed in PCT
Application No. JP2006/315901, the disclosures of which, as they
relate to silicone compositions, are hereby incorporated by
reference. Further, polysilsesquioxanes may also be suitable for
purposes of the present invention.
[0148] As set forth above, the reinforced silicone layer 16
comprises the fiber reinforcement. The fiber reinforcement can be
any reinforcement comprising fibers. The fiber reinforcement
typically has a Young's modulus at 25.degree. C. of at least 3 GPa.
For example, the reinforcement typically has a Young's modulus at
25.degree. C. of from 3 to 1,000 GPa, alternatively from 3 to 200
GPa, alternatively from 10 to 100 GPa.
[0149] Moreover, the reinforcement typically has a tensile strength
at 25.degree. C. of at least 50 MPa. For example, the reinforcement
typically has a tensile strength at 25.degree. C. of from 50 to
10,000 MPa, alternatively from 50 to 1,000 MPa, alternatively from
50 to 500 MPa.
[0150] The fiber reinforcement can be a woven fabric, e.g., a
cloth; a nonwoven fabric, e.g., a mat or roving; or loose
(individual) fibers. The fibers in the reinforcement are typically
cylindrical in shape and have a diameter of from 1 to 100 .mu.m,
alternatively from 1 to 20 .mu.m, alternatively form 1 to 10 .mu.m.
Loose fibers are typically continuous, meaning the fibers extend
throughout the reinforced silicone layer 16 in a generally unbroken
manner.
[0151] The fiber reinforcement is typically heat-treated prior to
use to remove organic contaminants. For example, the fiber
reinforcement is typically heated in air at an elevated
temperature, for example, 575.degree. C., for a suitable period of
time, for example 2 hours.
[0152] Specific examples of fiber reinforcements that are suitable
for purposes of the present invention include, but are not limited
to, reinforcements comprising glass fibers; quartz fibers; graphite
fibers; nylon fibers; polyester fibers; aramid fibers, such as
Kevlar.RTM. and Nomex.RTM.; polyethylene fibers; polypropylene
fibers; silicon carbide fibers; alumina fibers; silicon oxycarbide
fibers; metal wires such as steel wires; and combinations
thereof.
[0153] As set forth above, the fiber reinforcement is typically
impregnated with the silicone composition. The fiber reinforcement
may be impregnated with the silicone composition using a variety of
methods. For example, the silicone composition, as described above,
may be applied to a release liner to form a silicone film. The
silicone composition can be applied to the release liner using
conventional coating techniques, such as spin coating, dipping,
spraying, brushing, or screen-printing. The silicone composition is
applied in an amount sufficient to impregnate the fiber
reinforcement. The release liner can be any rigid or flexible
material having a surface from which the reinforced silicone layer
16 can be removed without damage by delamination after the silicone
resin is cured. Examples of release liners include, but are not
limited to, nylon, polyethyleneterephthalate, and polyimide.
[0154] The fiber reinforcement is then embedded in the silicone
film, thereby forming an embedded fiber reinforcement. The fiber
reinforcement can be embedded in the silicone film by simply
placing the reinforcement on the silicone film and allowing the
silicone composition to impregnate the reinforcement. However, it
is to be appreciated that the fiber reinforcement may be first
deposited on the release liner, followed by the application of the
silicone composition onto the fiber reinforcement. In another
embodiment, when the fiber reinforcement is woven or nonwoven
fabric, the reinforcement can be impregnated with the silicone
composition by passing it through the silicone composition without
the used of the release liner. The fabric is typically passed
through the silicone composition at a rate of from 1 to 1,000 cm/s
at room temperature (.about.23.+-.2.degree. C.).
[0155] The embedded fiber reinforcement is then optionally
degassed. The embedded fiber reinforcement can be degassed by
subjecting it to a vacuum at a temperature of from room temperature
(.about.23.+-.2.degree. C.) to 60.degree. C., for a period of time
sufficient to remove entrapped air in the embedded reinforcement.
For example, the embedded fiber reinforcement can typically be
degassed by subjecting it to a pressure of from 1,000 to 20,000 Pa
for 5 to 60 min. at room temperature.
[0156] After degassing, additional silicone composition is applied
to the embedded fiber reinforcement to form an impregnated fiber
reinforcement. The silicone composition can be applied to the
degassed embedded fiber reinforcement using conventional methods,
as described above. Additional cycles of degassing and application
of silicone composition may also occur.
[0157] The impregnated fiber reinforcement may also be compressed
to remove excess silicone composition and/or entrapped air, and to
reduce the thickness of the impregnated fiber reinforcement. The
impregnated fiber reinforcement can be compressed using
conventional equipment such as a stainless steel roller, hydraulic
press, rubber roller, or laminating roll set. The impregnated fiber
reinforcement is typically compressed at a pressure of from 1,000
Pa to 10 MPa and at a temperature of from room temperature
(.about.23.+-.2.degree. C.) to 50.degree. C.
[0158] The impregnated fiber reinforcement is heated at a
temperature sufficient to cure the silicone composition and form
the reinforced silicone layer 16. The impregnated fiber
reinforcement can be heated at atmospheric, sub-atmospheric, or
supra-atmospheric pressure. The impregnated fiber reinforcement is
typically heated at a temperature of from room temperature
(.about.23.+-.2.degree. C.) to 250.degree. C., alternatively from
room temperature to 200.degree. C., alternatively from room
temperature to 150.degree. C., at atmospheric pressure. The
impregnated fiber reinforcement is heated for a length of time
sufficient to cure (cross-link) the silicone composition. For
example, the impregnated fiber reinforcement is typically heated at
a temperature of from 150 to 200.degree. C. for a time of from 0.1
to 3 hours.
[0159] Alternatively, the impregnated fiber reinforcement can be
heated in a vacuum at a temperature of from 100 to 200.degree. C.
and a pressure of from 1,000 to 20,000 Pa for a time of from 0.5 to
3 hours to form the reinforced silicone layer 16. The impregnated
fiber reinforcement can be heated in the vacuum using a
conventional vacuum bagging process. In a typically process, a
bleeder (e.g., polyester) is applied over the impregnated fiber
reinforcement, a breather (e.g., nylon, polyester) is applied over
the bleeder, a vacuum bagging film (e.g., nylon) equipped with a
vacuum nozzle is applied over the breather, the assembly is sealed
with tape, a vacuum (e.g., 1,000 Pa) is applied to the sealed
assembly, and the evacuated bag is heated as described above.
[0160] The thickness of the reinforced silicone layer 16 is
dependent upon the intended application for the composite article
10. Typically, the reinforced silicone layer 16 has a thickness of
at least 1 mil, more typically from 2 to 100 mils, most typically
about 5 mils.
[0161] The reinforced silicone layer 16 is disposed adjacent to and
in contact with the first window layer 14. More specifically, the
reinforced silicone layer 16 is adhered to the first window layer
14. In one embodiment, as shown in FIG. 2, the reinforced silicone
layer 16 may be formed directly upon the first window layer 14. In
this embodiment, the silicone composition includes at least one
functional group prior to curing for adhering the cured silicone
composition, and the reinforced silicone layer 16, to the first
window layer 14. The at least one functional group may be selected
from the group of, but is not limited to, silanol groups, alkoxy
groups, epoxy groups, silicon hydride groups, acetoxy groups, and
combinations thereof.
[0162] As set forth above, to form the reinforced silicone layer 16
directly upon the first window layer 14, the impregnated fiber
reinforcement is formed as described above. The impregnated fiber
reinforcement is then placed onto the first window layer 14 prior
to completely curing the impregnated fiber reinforcement. Once the
impregnated fiber reinforcement is disposed on the first window
layer 14, the impregnated fiber reinforcement is heated to cure the
silicone composition and form the reinforced silicone layer 16 and
to adhere the reinforced silicone layer 16 onto the first window
layer 14. When the reinforced silicone layer 16 is formed directly
upon the first window layer 14, it is important to ensure that the
first vitreous material used to form the first window layer 14 is
capable of withstanding the temperatures used to cure the silicone
composition without degrading or deforming. This is particularly
applicable when the first vitreous material comprises the
carbon-based polymer.
[0163] In another embodiment, as shown in FIG. 3, the first pane 12
may further include an adhesive layer 26 disposed between the
reinforced silicone layer 16 and the first window layer 14. More
specifically, the reinforced silicone layer 16 is adhered to the
first window layer 14 with the adhesive layer 26. The adhesive
layer 26 typically comprises a silicone-based adhesive; however, it
is to be appreciated that any adhesive suitable for adhering
silicone to glass is suitable for purposes of the present
invention. The silicone-based adhesive may provide further
fire-resistance to the composite article 10 that may not be
possible by using primarily carbon-based adhesives. The
silicone-based adhesive typically includes at least one functional
group for adhering the adhesive layer 26 to the reinforced silicone
layer 16, and also for adhering the adhesive layer 26 to the first
window layer 14. The at least one functional group may be selected
from the group of, but is not limited to, silanol groups, alkoxy
groups, epoxy groups, silicon hydride groups, acetoxy groups, and
combinations thereof. Such silicone-based adhesives are known in
the art. The silicone-based adhesive may be provided as a one part
or a multi-part system. In one embodiment, the adhesive may be
formed from the same silicone composition that is used to form the
reinforced silicone layer 16.
[0164] Typically, as shown in FIG. 4, the first pane 12 further
comprises an additional window layer 28 formed from an additional
vitreous material and disposed adjacent to and in contact with the
reinforced silicone layer 16 and opposite the first window layer
14. That is, the reinforced silicone layer 16 is typically
sandwiched between the first window layer 14 and the additional
window layer 28 to protect the reinforced silicone layer 16 from
scratching or other damage. The additional window layer 28 may be
the same as or different from the first window layer 14, and the
additional vitreous material may be the same as or different from
the first vitreous material. For example, the first window layer 14
and the additional window layer 28 may have different thicknesses,
and may be formed from different vitreous materials that are
described above.
[0165] As shown in FIG. 5, the first pane 12 may include an
additional adhesive layer 26 disposed between the reinforced
silicone layer 16 and the additional window layer 28. The adhesive
layer 26 is described above.
[0166] The composite article 10 further includes a second pane 18.
Typically, as shown in FIG. 6, the second pane 18 includes a second
window layer 22 formed from a second vitreous material. The second
window layer 22 may be the same or different from the first window
layer 14 and the additional window layer 28, and the second
vitreous material may be the same or different from the first
vitreous material and the additional vitreous material. For
example, the first window layer 14 and the second window layer 22
and the additional window layer 28 may have different thicknesses,
and may be formed from different vitreous materials that are
described above.
[0167] The second pane may further comprise a second silicone layer
32. The second silicone layer 32 is typically disposed adjacent to
and in contact with the second window layer 22. The second silicone
layer 32 may be adhered to the second window layer 22 in the same
manner as the reinforced silicone layer 16. More specifically, as
shown in FIG. 6, the second silicone layer 32 may be formed
directly upon the second window layer 22. Alternatively, as shown
in FIG. 7, the composite article 10 may further include the
adhesive layer 26 disposed between the second silicone layer 32 and
the second window layer 22. The adhesive layer 26 is described
above. The second silicone layer 32 may further include the fiber
reinforcement, and the second silicone layer 32 including the fiber
reinforcement may be prepared in the same manner as the reinforced
silicone layer 16 described above. Alternatively, the second
silicone layer 32 may be formed in the absence of the fiber
reinforcement. The second silicone layer 32 may be the same or
different from the reinforced silicone layer 16 in terms of
thickness, type of fiber reinforcement, or type of cured silicone
composition.
[0168] As shown in FIG. 8, the second pane 18 may further comprise
the additional window layer 28 formed from the additional vitreous
material and disposed adjacent to and in contact with the second
silicone layer 32 and opposite the second window layer 22. That is,
the second silicone layer 32 may be sandwiched between the second
window layer 22 and the additional window layer 28 to protect the
second silicone layer 32 from scratching or other damage. Another
adhesive layer 26 may be disposed between the second silicone layer
32 and the additional window layer 28 to adhere the second silicone
layer 32 and the additional window layer 28.
[0169] Referring to FIGS. 1 and 1-A, the second pane 18 is spaced
from the first pane 12 to define a gap 20 between the first pane 12
and the second pane 18. The composite article 10 further includes a
frame 24 disposed adjacent to and in contact with the first pane 12
and the second pane 18. The frame 24 encloses the gap 20 between
the first pane 12 and the second pane 18 and maintains the first
pane 12 and the second pane 18 in spaced relationship. The frame 24
is typically disposed adjacent peripheral edges of the first pane
12 and the second pane 18, and the frame 24 may comprise a
continuous strip of material extending uninterrupted adjacent the
peripheral edges of the first pane 12 and the second pane 18. While
the frame 24 is shown in the Figures as residing in the gap 20, it
is to be appreciated that other configurations of the frame 24 are
also possible so long as the frame 24 both maintains the first pane
12 spaced from the second pane 18 and encloses the gap 20. It is
also to be appreciated that the gap 20 may be in fluid
communication with the ambient atmosphere and that by enclosing the
gap 20, the frame 24 need not necessarily seal the gap 20 from the
ambient environment. As such, by "enclosing" the gap 20, partial
enclosure is contemplated in addition to complete enclosure. Thus,
the frame 24 may be discontinuous. However, in one embodiment, the
frame 24 may seal the gap 20.
[0170] In one embodiment, the frame 24 is formed from an adhesive.
As such, the frame 24 may be directly adhered to the first pane 12
and the second pane 18. The adhesive may comprise the
silicone-based adhesive as described above for the adhesive layer
26; however, it is to be appreciated that any adhesive suitable for
adhering to glass is suitable for purposes of the present
invention. Use of the silicone-based adhesive for the frame 24 may
further improve fire resistance of the composite article 10, as
compared to the use of other materials for the frame 24.
[0171] The frame 24 may be formed by providing at least one strip
of the adhesive and adhering the strip to the first pane 12 and/or
the second pane 18. That is, the adhesive is typically provided in
strips having a width of from about 0.5 cm to 10 cm wide and a
length corresponding to the length of an edge of the first pane 12
or the second pane 18. It is to be understood that the width of the
strip is dependent upon the total size of the first pane 12 and the
second pane 18. That is, a larger first pane 12 and a larger second
pane 18 may require wider strips than required for a smaller first
pane 12 and a smaller second pane 18. It is to be appreciated that
the frame 24 may be formed from one continuous strip of adhesive or
from a plurality of strips of adhesive. Thickness of the frame 24
is dependent upon the intended application for the composite
article 10. The frame 24 typically has a thickness of from about
0.1 mm to about 5 mm, alternatively from about 1 mm to about 3
mm.
[0172] Alternatively, the frame 24 may be formed from any
non-adhesive material suitable for separating the first pane 12 and
the second pane 18. Suitable materials for separating the first
pane 12 and the second pane 18 include, but are not limited to,
plastic, wood, paper, metal, foam, adhesives, and combinations
thereof. In this embodiment, the frame 24 is typically adhered to
the first pane 12 and the second pane 18 by the silicone-based
adhesive as set forth above. However, it is to be appreciated that
any adhesive may be used. Further, the frame 24 may be shaped to
mechanically connect the first pane 12 and the second pane 18. Such
configurations are known in the art.
[0173] Due to the presence of the gap 20 between the first pane 12
and the second pane 18, the composite article 10 exhibits excellent
thermal and acoustic insulation. Width of the gap 20 is dependent
upon the intended application for the composite article 10. The gap
20 typically has a width of from about 1 mm to about 30 mm,
alternatively from about 5 mm to about 25 mm, alternatively from
about 10 mm to about 20 mm. In one embodiment, a pressure inside
the gap 20 may be less than about 0.1 atm to effectively create a
vacuum within the gap 20. In another embodiment, an insulator is
disposed inside the gap 20. Any suitable insulator known in the art
for providing thermal and acoustic insulation may be disposed
inside the gap 20. For example, the insulator may be selected from
the group of air, argon, helium, nitrogen gas, and combinations
thereof.
[0174] In another embodiment, as shown in FIG. 9, the composite
article 10 may comprise a third pane 30. The third pane 30
typically comprises a third window layer 36 formed from a third
vitreous material and a third silicone layer 34. The third window
layer 36 may be the same as or different from the first window
layer 14, the additional window layer 28, and the second window
layer 22. Likewise, the third vitreous material may be the same as
or different from the first vitreous material, the additional
vitreous material, and/or the second vitreous material. The third
pane 30 may be independently configured in the same manner as the
first pane 12 and the second pane 18 as described above. The third
silicone layer 34 may further include the fiber reinforcement, and
the third silicone layer 34 including the fiber reinforcement may
be prepared in the same manner as the reinforced silicone layer 16
described above. Alternatively, the third silicone layer 34 may be
formed in the absence of the fiber reinforcement. The third
silicone layer 34 may be the same as or different from the
reinforced silicone layer 16 and/or the second silicone layer 32 in
terms of thickness, type of fiber reinforcement, or type of cured
silicone composition.
[0175] As shown in FIG. 9, the third pane 30 may be disposed
adjacent to and in contact with the first window layer 14 to
provide additional structural rigidity and fire resistance to the
composite article 10. It is to be appreciated that the composite
articles 10 of the present invention may further comprise a
plurality of additional panes 12, 18, 30 in order to provide
additional structural rigidity and fire resistance to the composite
articles 10.
[0176] In another embodiment, as shown in FIG. 10, the third pane
30 may be spaced from the first pane 12 and the second pane 18 and
may define at least one gap 20 therebetween. That is, the composite
article 10 may comprise a plurality of gaps 20. Additional frames
24 may be used to maintain the gaps 20 as necessary. The number of
gaps 20 depends on the desired thermal and acoustic insulation,
structural rigidity, fire performance rating, and
mechanical/thermal impact resistance requirements of the composite
article 10. Generally, a greater number of gaps 20 in the composite
article 10 provides higher thermal and acoustic insulation to the
composite article 10.
[0177] A low E coating may be disposed either on or within at least
one of the panes. More specifically, the low E coating may be
disposed on an outer surface of at least one of the panes.
Alternatively, the low E coating may be disposed within at least
one of the panes, such as between a window layer and a reinforced
silicone layer.
[0178] The composite articles 10 of the present invention have
excellent thermal and acoustic insulation. More specifically, the
composite articles 10 of the present invention typically have an
acoustic insulation rating of at least STC 31 in accordance with
ASTM E90. The composite articles 10 of the present invention
typically have a thermal insulation rating (measured as "U value")
of at least 0.55 in accordance with ASTM E2188.
[0179] The composite articles 10 of the present invention have
excellent fire resistance. More specifically, the composite
articles 10 of the present invention typically have a fire rating
of at least 30 minutes in accordance with at least one of ASTM E
119-05a without a hose stream impact, ASTM E 2010-01 with a hose
stream impact, and ASTM E 2074-00. The fire rating is an indication
of the fire resistance of the composite article 10 and is a
measurement of how long it takes to form a breach in the composite
article 10 when exposed to heat provided by a furnace. To establish
a fire rating in accordance with ASTM E 119-05a, the composite
article 10 is fitted onto one opening of the furnace, and a flame
is started in the furnace to raise the temperature inside the
furnace from room temperature to about 200.degree. F., and a supply
of fuel to the flame is gradually increased to generate a
predetermined temperature profile and to reach a temperature of
about 1950.degree. F. at the end of a period of 190 minutes.
Although the breach will form in the composite article 10 during
exposure to the heat, the vitreous material used to form the window
layers of the composite article 10 typically melts, and the
reinforced silicone layer 16 typically chars.
[0180] Even once a breach forms in the composite article 10 of the
present invention, the composite articles 10 may maintain
substantial structural integrity due to the presence of the fiber
reinforcement in the reinforced silicone layer 16. More
specifically, the composite article 10 will typically not collapse
from its own weight regardless of the extent of charring due to the
presence of the fiber reinforcement.
[0181] The following examples are meant to illustrate the invention
and are not to be viewed in any way as limiting to the scope of the
invention.
Example 1
[0182] A composite article is formed by providing a first pane, a
second pane spaced from the first pane to define a gap
therebetween, and a frame disposed adjacent to and in contact with
the first pane and the second pane. The first pane, the second
pane, and the frame enclose the gap between the first pane and the
second pane.
[0183] More specifically, a first window layer, a second window
layer, and an additional window layer are formed from annealed
float glass having a thickness of about 0.125 inch. The first
window layer, the second window layer, and the additional window
layer each have a width of about 6 inches, a length of about 6
inches, and four edges. The first window layer, the second window
layer, and the additional window layer are washed with soap water,
rinsed with de-ionized water, and dried before use.
[0184] Adhesive layers are formed from an adhesive. The adhesive is
prepared by mixing 60% by weight of a vinyl-terminated
polydimethylsiloxane fluid with 40% by weight of a trimethylsiloxy
surface treated fumed silica, a
polydimethyl-methylhydrogen-siloxane with an equimolar amount of
SiH equal to that of the vinyl in the polydimethylsiloxane fluid,
and 10 ppm Pt(0) as a complex with divinyltetramethyldisiloxane.
The adhesive is commercially available from Dow Corning Corporation
of Midland, Mich. The adhesive is extruded onto a polysulfone film
and partially cured to form the adhesive layer. The adhesive layer
is peeled off from the polysulfone film and adhered to the first
window layer.
[0185] A reinforced silicone layer includes a cured silicone
composition and a fiber reinforcement. The cured silicon
composition is formed from a liquid silicone resin comprising a
vinyl-terminated phenyl silsesquioxane resin and a liquid
SiH-functional crosslinker commercially available from Dow Corning
Corporation of Midland, Mich. The fiber reinforcement comprises a
Style 106 glass fabric, commercially available from BGF Industries
of Greensboro, N.C., and has a thickness of about 1.5 mils. The
reinforced silicone layer is prepared by saturating the fiber
reinforcement with a mixture of the silicone resin and the
crosslinker and curing in an oven. The reinforced silicone layer is
adhered to the adhesive layer, opposite the first window layer.
[0186] To form the first pane, an additional adhesive layer is
adhered to the reinforced silicone layer, and the additional window
layer is adhered to the additional adhesive layer opposite the
reinforced silicone layer. The first pane is enclosed in a vacuum
bag and placed in an oven to cure under vacuum. The oven
temperature rises from ambient at a rate of about 1.degree. C./min
until the oven temperature is 130.degree. C. The oven temperature
is maintained at 130.degree. C. for 30 hours. After 30 hours, the
oven is switched off and allowed to cool. After cooling, the first
pane is removed from the vacuum bag, cleaned, and dried. The first
pane may be represented by: G.sub.1/AFA/G.sub.A, where G.sub.1=the
first window layer, A=the adhesive layer (or the additional
adhesive layer), and F=the reinforced silicone layer, and
G.sub.A=the additional window layer.
[0187] To form the frame, an adhesive is prepared according to the
method as set forth above for preparing the adhesive layer. The
adhesive is formed into a layer having a thickness of about 2 mm
and cut into four strips, each strip having a width of 1 cm. The
four strips are disposed adjacent to and in contact with the edge
of the first pane.
[0188] To form the composite article, the second pane comprising a
second window layer is disposed adjacent to and in contact with the
frame to define the gap. The composite article is annealed at
150.degree. C. for 30 minutes under a pressure applied by a weight
on the composite article to seal the gap. The resulting composite
article may be represented by:
G.sub.1/AFA/G.sub.A/B/G.sub.2
where G.sub.1=the first window layer, A=the adhesive layer, and
F=the silicone resin layer, G.sub.A=the additional window layer,
B=the frame, and G.sub.2=the second window layer.
[0189] The composite article of Example 1 provides acoustic
insulation rated as at least STC 31 according to ASTM E90. The
composite article of Example 1 has a fire rating of at least 30
minutes in accordance with ASTM E 119-05a without a hose stream
impact. To test the fire resistance of the composite article of
Example 1, the composite article is fitted onto an opening of a
furnace, with one side of the composite article exposed to the
ambient atmosphere. The furnace is heated at a rate indicated in
ASTM E119.
Example 2
[0190] A composite article is formed by providing two panes
prepared in the same manner as the first pane of Example 1, and the
frame of Example 1. To form the composite article of Example 2, the
two panes are spaced apart from each other to define a gap
therebetween. The frame is disposed between and adhered to the two
panes to enclose the gap between the two panes. The composite
article is annealed at 150.degree. C. for 30 minutes under a
pressure applied by a weight on the composite article to seal the
gap. The resulting composite article of Example 2 may be
represented by:
G.sub.1/AFA/G.sub.A/B/G.sub.A/AF.sub.2A/G.sub.2
where G.sub.i=the first window layer of Example 1, A=the adhesive
layer of Example 1, and F=the reinforced silicone layer of Example
1, G.sub.A=the additional window layer of Example 1, B=the frame of
Example 1, F.sub.2=the reinforced silicone layer of Example 1, and
G.sub.2=the second window layer of Example 1.
[0191] The composite article of Example 2 provides acoustic
insulation rated as at least STC 31 according to ASTM E90. The
composite article of Example 2 has a fire rating of at least 30
minutes in accordance with ASTM E 119-05a without a hose stream
impact. Fire resistance is tested in the same manner as outlined in
Example 1.
Example 3
[0192] A composite article is formed by providing the composite
article of Example 1, an additional reinforced silicone layer, and
an additional window layer.
[0193] To form the composite article of Example 3, the additional
window layer is formed in the same manner as the window layers of
Example 1. A laminate including the additional window layer and the
additional silicone layer is prepared by adhering the additional
silicone layer to the additional window layer through an adhesive
layer, and then adhering another adhesive layer to the additional
silicone layer opposite the additional window layer. That is, the
additional silicone layer is disposed between two adhesive layers,
with the additional window layer adhered to one of the adhesive
layers. The laminate may be represented by:
G.sub.A/AF.sub.2A
where G.sub.A=the additional window layer, A=the adhesive layer,
and F.sub.2=the additional silicone layer.
[0194] To form the composite article of Example 3, the laminate is
adhered to the composite article of Example 1 through the adhesive
layer that remains free in the laminate. The composite article of
Example 3 may be represented by:
G.sub.A/AF.sub.2A/G.sub.1/AFA/G.sub.A/B/G.sub.2
where G.sub.A=the additional window layer, A=the adhesive layer,
F.sub.2=the additional silicone layer, G.sub.1=the first window
layer, and F=the reinforced silicone layer, B=the frame, and
G.sub.2=the second window layer.
[0195] The composite article of Example 3 provides acoustic
insulation rated as at least STC 31 according to ASTM E90. The
composite article of Example 3 has a fire rating of at least 30
minutes in accordance with ASTM E 119-05a without a hose stream
impact. Fire resistance is tested in the same manner as outlined in
Example 1.
[0196] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings, and the
invention may be practiced otherwise than as specifically described
within the scope of the appended claims.
* * * * *