U.S. patent application number 09/733186 was filed with the patent office on 2001-12-20 for ceramer composition incorporating fluoro/silane component and having abrasion and stain resistant characteristics.
Invention is credited to Kang, Soonkun, Moore, George G. I..
Application Number | 20010053445 09/733186 |
Document ID | / |
Family ID | 27372105 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010053445 |
Kind Code |
A1 |
Kang, Soonkun ; et
al. |
December 20, 2001 |
Ceramer composition incorporating fluoro/silane component and
having abrasion and stain resistant characteristics
Abstract
A curable ceramer composition, coated articles and methods for
making and curing the composition. The curable ceramer comprises a
fluoro/silane, a crosslinkable silane, a curable binder precursor,
and a colloidal inorganic oxide. The ceramer has a long shelf life
before cure and can be used to provide cured ceramer coatings and
articles having stain resistance, abrasion resistance and
hardness.
Inventors: |
Kang, Soonkun; (Lake Elmo,
MN) ; Moore, George G. I.; (Afton, MN) |
Correspondence
Address: |
David R. Cleveland, P.A.
Suite E-1324
332 Minnesota St.
St. Paul
MN
55101
US
|
Family ID: |
27372105 |
Appl. No.: |
09/733186 |
Filed: |
December 8, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09733186 |
Dec 8, 2000 |
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09389252 |
Sep 3, 1999 |
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6245833 |
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09389252 |
Sep 3, 1999 |
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09209117 |
Dec 10, 1998 |
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09209117 |
Dec 10, 1998 |
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09072506 |
May 4, 1998 |
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Current U.S.
Class: |
428/421 ;
427/389; 427/393.5; 427/493; 427/515; 428/447; 524/786;
524/790 |
Current CPC
Class: |
Y10T 428/3154 20150401;
Y10T 428/31663 20150401; C09D 4/00 20130101; C09D 4/00 20130101;
C08F 230/085 20200201; C09D 4/00 20130101; C08F 222/103
20200201 |
Class at
Publication: |
428/421 ;
428/447; 524/790; 524/786; 427/493; 427/515; 427/389;
427/393.5 |
International
Class: |
B32B 027/00; B32B
005/16; B32B 027/00; B05D 007/12; B05D 003/02; B32B 009/02; C08K
003/22 |
Claims
We claim:
1. A method of making a curable ceramer composition, comprising the
step of combining a fluoro/silane component with an admixture
comprising colloidal inorganic oxide and curable binder precursor,
said combining step occurring in the presence of a crosslinkable
silane component; wherein the fluoro/silane component comprises a
hydrolyzable silane moiety and a fluorinated moiety, the
crosslinkable silane component comprises a hydrolyzable silane
moiety and a polymerizable moiety other than a silane moiety, and
the curable binder precursor comprises a polymerizable moiety
copolymerizable with the polymerizable moiety of the crosslinkable
silane component; said combining step further occurring under
conditions such that at least a portion of the colloidal inorganic
oxide is surface treated by the fluoro/silane component.
2. The method of claim 1, wherein the admixture comprises a sol of
colloidal inorganic oxides.
3. The method of claim 2, further comprising the step of stripping
the composition to remove water.
4. The method of claim 3, further comprising the step of adding an
organic solvent to the stripped composition to form a coatable
composition containing from about 5% to about 95% solids by
weight.
5. The method of claim 1, wherein the weight ratio of the
crosslinkable silane to the fluoro/silane is between 4:1 and
20:1.
6. The method of claim 1, wherein the crosslinkable silane
component is represented by the
formula:(S.sub.y).sub.q--W.sup.o--(R.sub.c).sub.pwhere- in S.sub.y
represents a hydrolyzable silane moiety; R.sub.c is a moiety
comprising free-radically polymerizable functionality; q is at
least 1; p is at least 1; and W.sup.o is a linking group having a
valency of q+p.
7. The method of claim 1, wherein the fluoro/silane component is
represented by the
formula:(S.sub.y).sub.r--W--(R.sub.f).sub.swherein S.sub.y
represents a hydrolyzable silane moiety; R.sub.f represents a
fluorinated moiety; r is at least 1; s is at least 1; and W is a
linking group having a valency of r+s.
8. The method of claim 1, wherein the curable binder precursor
comprises one or more (meth)acrylate or (meth)acrylamide
monomers.
9. The method of claim 1, wherein the inorganic oxide comprises a
mixture of a major amount of silica and a minor amount of at least
one other inorganic oxide.
10. The method of claim 9, wherein the other inorganic oxide
comprises alumina.
11. A curable ceramer composition, comprising: (a) curable binder
precursor; and (b) colloidal inorganic oxide surface treated with a
surface treatment agent that comprised: (i) fluoro/silane component
that comprised a hydrolyzable silane moiety and a fluorinated
moiety, and (ii) crosslinkable silane component that comprised a
hydrolyzable silane moiety and a free-radically crosslinkable
moiety.
12. The curable ceramer composition of claim 11, wherein the weight
ratio of the crosslinkable silane component to the fluoro/silane
component was from about 4:1 to about 20:1.
13. The curable ceramer composition of claim 11, wherein the
crosslinkable silane component had the
formula:(S.sub.y).sub.q--W.sup.o--(R.sub.c).sub.- pwherein S.sub.y
represents a hydrolyzable silane moiety; R.sub.c is a moiety
comprising free-radically polymerizable functionality; q is at
least 1; p is at least 1; and W.sup.o is a linking group having a
valency of q+p.
14. The curable ceramer composition of claim 11, wherein the
fluoro/silane component had the
formula:(S.sub.y).sub.r--W--(R.sub.f).sub.swherein S.sub.y
represents a hydrolyzable silane moiety; R.sub.f represents a
fluorinated moiety; r is at least 1; s is at least 1; and W is a
linking group having a valency of r+s.
15. The curable ceramer composition of claim 11, wherein the
curable binder precursor comprises one or more (meth)acrylate or
(meth)acrylamide monomers.
16. The curable ceramer composition of claim 11, wherein the
curable binder precursor comprises pentaerythritol triacrylate.
17. The curable ceramer composition of claim 16, wherein the
curable binder precursor also comprises N,N-dimethyl (meth)
acrylamide.
18. The curable ceramer composition of claim 11, wherein the
colloidal inorganic oxide comprises colloidal silica particles.
19. The curable ceramer composition of claim 11, wherein the
inorganic oxide comprises a mixture of a major amount of silica and
a minor amount of at least one other inorganic oxide.
20. The curable ceramer composition of claim 19, wherein the other
inorganic oxide comprises alumina.
21. A composite structure, comprising a polymeric or leather
substrate having a surface at least partially coated with a cured
ceramer composite composition of claim 1 1.
22. A method of making an abrasion resistant ceramer coating,
comprising the steps of: (a) coating at least a portion of a
substrate surface with the curable ceramer composition of claim 11;
(b) irradiating the coated substrate with an amount of curing
energy under conditions effective to at least partially cure the
composition, whereby an abrasion resistant cured ceramer coating is
formed on the substrate.
23. The method of claim 22, further comprising the step of heating
the coating prior to irradiating.
Description
RELATED APPLICATION INFORMATION
[0001] This application is a continuation-in-part of pending prior
application Ser. Nos. 09/209,117, filed Dec. 10, 1998, which was a
continuation-in-part of then-pending prior application Ser. No.
09/072,506, filed May 4, 1998.
FIELD OF THE INVENTION
[0002] This invention relates to abrasion resistant protective
coatings and methods of making the same. This invention also
relates to abrasion resistant coatings derived from a ceramer
composite.
BACKGROUND OF THE INVENTION
[0003] Thermoplastic and thermosetting polymers are used to form a
wide variety of structures for which optical clarity, i.e., good
light transmittance, is a desired characteristic. Examples of such
structures include camera lenses, eyeglass lenses, binocular
lenses, retroreflective sheeting, non-retroreflective graphic
displays, automobile windows, building windows, train windows, boat
windows, aircraft windows, vehicle headlamps and taillights,
display cases, eyeglasses, watercraft hulls, road pavement
markings, overhead projectors, stereo cabinet doors, stereo covers,
furniture, bus station plastic, television screens, computer
screens, watch covers, instrument gauge covers, bakeware, optical
and magneto-optical recording disks, and the like. Examples of
polymer materials used to form these structures include
thermosetting or thermoplastic polycarbonate, poly(meth)acrylate,
polyurethane, polyester, polyamide, polyimide, phenoxy, phenolic
resin, cellulosic resin, polystyrene, styrene copolymer, epoxy, and
the like.
[0004] Many of these thermoplastic and thermosetting polymers have
excellent rigidity, dimensional stability, transparency, and impact
resistance, but unfortunately have poor abrasion resistance.
Consequently, structures formed from these polymers are susceptible
to scratches, abrasion, and similar damage.
[0005] To protect these structures from physical damage, a tough,
abrasion resistant "hardcoat" layer may be coated onto the
structure. Many previously known hardcoat layers incorporate a
binder matrix formed from radiation curable prepolymers such as
(meth)acrylate functional monomers. Such hardcoat compositions have
been described, for example, in Japanese patent publication
JPO2-260145, U.S. Pat. No. 5,541,049, and U.S. Pat. No. 5,176,943.
One particularly excellent hardcoat composition is described in WO
96/36669 A1. This publication describes a hardcoat formed from a
"ceramer" used, in one application, to protect the surfaces of
retroreflective sheeting from abrasion. As defined in this
publication, a ceramer is a hybrid polymerizable composite
(preferably transparent) having inorganic oxide particles, e.g.,
silica, of nanometer dimensions dispersed in an organic binder
matrix.
[0006] Many ceramers are derived from aqueous sols of inorganic
colloids according to a process in which a radiation curable binder
matrix precursor (e.g., one or more different radiation curable
monomers, oligomers, or polymers) and other optional ingredients
(such as surface treatment agents that interact with the colloids
of the sol, surfactants, antistatic agents, leveling agents,
initiators, stabilizers, sensitizers, antioxidants, crosslinking
agents, and crosslinking catalysts) are blended into the aqueous
sol. The resultant composition is then dried to remove
substantially all of the water. The drying step may also be
referred to as "stripping". An organic solvent may then be added,
if desired, in amounts effective to provide the composition with
viscosity characteristics suitable for coating the composition onto
the desired substrate. After coating, the composition can be dried
to remove the solvent and then exposed to a suitable source of
energy to cure the radiation curable binder matrix precursor.
SUMMARY OF THE INVENTION
[0007] The manufacture of ceramer compositions can be challenging
due to the extremely sensitive characteristics of the colloids of
the aqueous sol. Particularly, adding other ingredients, such as
binder matrix precursors or other additives, to such sols tends to
destabilize the colloids, causing the colloids to flocculate, e.g.,
precipitate out of the sol. Flocculation is not conducive to
forming high quality coatings. First, flocculation results in local
accumulations of particles. These accumulations are typically large
enough to scatter light which results in a reduction of the optical
clarity of the resultant coating. In addition, the accumulation of
particles may cause nibs or other defects in the resultant
coatings. In short, flocculation of the colloids causes the
resultant ceramer composition to be cloudy, or hazy, and thus,
coatings formed from the ceramer composition could be cloudy or
hazy as well. Conversely, if colloid flocculation were to be
avoided, the resultant ceramer composition would remain optically
clear, allowing coatings containing the ceramer composition to be
optically clear as well.
[0008] Thus, the manufacture of ceramer compositions may require
special processing conditions that allow binder precursors or
additives to be incorporated into a sol to avoid colloid
flocculation. Unfortunately, the processing conditions developed to
manufacture one ceramer composition are often not applicable to the
manufacture of a ceramer containing different components.
[0009] One method of manufacturing ceramers from aqueous, colloidal
sols involves incorporating one or more N,N-disubstituted
(meth)acrylamide monomers, preferably N,N-dimethyl (meth)acrylamide
(hereinafter referred to as "DMA"), into the binder matrix
precursor. The presence of such a radiation curable material
advantageously stabilizes the colloids, reducing the sensitivity of
the colloids to the presence of other ingredients that might be
added to the sol. By stabilizing the colloids, the presence of
materials like DMA makes ceramers easier to manufacture. In
addition to enhancing colloid stability, DMA provides other
benefits. For example, ceramer compositions containing DMA show
better adhesion to polycarbonate or acrylic substrates and better
processability as compared to otherwise identical ceramer
compositions lacking DMA.
[0010] Unfortunately, the use of DMA also has some drawbacks. A
ceramer composition incorporating DMA tends to attract or bind with
acidic contaminants (coffee, soda pop, citrus juices, and the like)
in the environment. Thus, ceramers incorporating DMA tend to be
more vulnerable to staining.
[0011] Accordingly, it would be desirable to find an alternative
approach for making ceramers without DMA, or with reduced amounts
of DMA, such that (1) the colloids are sufficiently stable during
ceramer manufacture, (2) the resultant ceramer is stain resistant,
or (3) the resultant ceramer retains excellent hardness and
abrasion resistance.
[0012] Fluorochemicals have low surface energy characteristics that
would satisfy at least one of the aforementioned criteria.
Specifically, because compositions with lower surface energy
generally tend to show better stain resistance, the incorporation
of a fluorochemical into a ceramer would be likely to enhance the
ceramer's stain resistance. Unfortunately, however, the
incorporation of fluorochemicals into a ceramer sol is extremely
difficult. For example, because fluorochemicals are both
hydrophobic (incompatible with water) and oleophobic (incompatible
with nonaqueous organic substances), the incorporation of a
fluorochemical into a ceramer sol often results in phase
separation, e.g., colloid flocculation. This undesirable colloid
flocculation can also result during the stripping process, when
water is typically removed from the blended aqueous sol.
[0013] Consequently, it would further be desirable to find a way to
provide ceramers with good stain resistance using fluorochemicals
or other stain resistant additives, while avoiding compatibility
and hardness problems generally associated with
fluorochemicals.
[0014] The present invention provides a method for effectively
incorporating a fluorochemical into a ceramer composition.
According to the invention, a nonionic fluorochemical containing
both a fluorinated moiety and a hydrolyzable silane moiety (the
"fluoro/silane component") can be successfully incorporated into a
ceramer sol, without causing appreciable colloid flocculation, to
provide ceramer coatings with surprisingly long shelf lives and
excellent stain resistant characteristics. Ceramers incorporating
such a fluorochemical also retain a high level of abrasion
resistance and hardness.
[0015] The present invention involved not just discovering the
advantages offered by the fluoro/silane component, but also
involved developing processing techniques that would allow the
fluoro/silane component to be incorporated into the sol without
causing flocculation of the colloids. Flocculation can be
substantially prevented if the fluoro/silane component is added to
an admixture containing a colloidal inorganic oxide and a curable
binder precursor (the "first admixture") in the presence of a
surface treatment agent containing both a hydrolyzable silane
moiety and a polymerizable moiety (a "crosslinkable silane
component"). The fluoro/silane component and the crosslinkable
silane component may be combined to form a second admixture, which
is then combined with the first admixture to form a third admixture
which after stripping will provide a curable ceramer composition of
the present invention. Alternatively, the crosslinkable silane
component may be combined with the first admixture individually,
after which the fluoro/silane component may then be added. In
contrast, if the fluoro/silane component is added to the sol
individually in the absence of, e.g., before, the crosslinkable
silane component, colloid flocculation tends to occur as soon as
the crosslinkable silane component is added or during stripping.
The effects caused by the order of addition of the crosslinkable
silane and the fluoro/silane tend to be observed in larger scale
processes rather than in bench scale processes. In bench scale
processes, it may be possible to add the fluoro/silane component to
the sol in the absence of the crosslinkable silane without
observing appreciable flocculation.
[0016] The present invention also provides ceramer compositions
containing a mixture of inorganic oxides. The oxides are present as
a major portion of one inorganic oxide and a minor portion of a
different inorganic oxide, resulting in cured ceramer coatings with
improved physical properties compared to coatings made with only
one inorganic oxide.
[0017] Accordingly, in one aspect, the present invention relates to
a method of making a curable ceramer composition by combining a
fluoro/silane component with an admixture containing one or more
colloidal inorganic oxides and a curable binder precursor. The
fluoro/silane component is added to the admixture in the presence
of a crosslinkable silane component. The fluoro/silane component
contains a hydrolyzable silane moiety and a fluorinated moiety. The
crosslinkable silane component contains a hydrolyzable silane
moiety and a polymerizable moiety other than a silane moiety. The
curable binder precursor contains one or more polymerizable
moieties copolymerizable with the polymerizable moiety of the
crosslinkable silane component. At least a portion of the colloidal
inorganic oxide is surface treated by the fluoro/silane component.
The resultant ceramer composition may be used directly if desired.
When the colloids are provided as an aqueous sol, the ceramer
composition is typically stripped and optionally diluted in an
appropriate solvent to provide a viscosity suitable for coating
onto a desired substrate.
[0018] In another aspect, the present invention relates to a method
of making an abrasion resistant ceramer coating using
free-radically-curable embodiments of the ceramer composition
described above. At least a portion of a substrate surface is
coated with the ceramer composition, after which the coated
substrate is irradiated with an amount of curing energy under
conditions effective to at least partially cure the coated
free-radically-curable ceramer composition, whereby an abrasion
resistant ceramer coating is formed on the substrate.
[0019] In another aspect, the present invention relates to a
free-radically-curable ceramer composition. The ceramer composition
includes a free-radically-curable binder precursor; and a plurality
of surface treated, colloidal inorganic oxide particles that are
surface treated with the fluoro/silane component.
[0020] In another aspect, the present invention relates to a cured,
abrasion resistant ceramer composite derived from this
free-radically-curable ceramer composition.
[0021] The ceramer composition of the present invention can be
utilized to provide substrates with durability, dry soil
resistance, long-lasting stain release properties and in some
cases, water and oil repellency. Thus, the present invention also
relates to a composite structure, comprising a polymeric substrate
having a coatable surface. A cured, abrasion resistant ceramer
coating of the present invention is provided on the coatable
surface of the substrate.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0022] The embodiments of the present invention described below are
not intended to be exhaustive or to limit the invention to the
precise forms disclosed in the following detailed description.
Rather the embodiments are chosen and described so that others
skilled in the art may appreciate and understand the principles and
practices of the present invention.
[0023] One embodiment of a preferred ceramer composition of the
present invention is prepared from ingredients containing a
compound having at least one hydrolyzable silane moiety and at
least one fluorinated moiety ("fluoro/silane component"), a
compound having at least one hydrolyzable silane moiety and at
least one polymerizable moiety other than a silane moiety
("crosslinkable silane component"), a curable binder precursor
having at least one polymerizable moiety that is co-polymerizable
with the polymerizable moiety of the crosslinkable silane
component, and one or more colloidal inorganic oxides. Preferably,
the fluoro/silane component and the crosslinkable silane component
are nonionic in embodiments of the invention in which the colloidal
inorganic oxide is provided as a sol. The use of nonionic materials
minimizes the tendency of the colloids to flocculate when the
ingredients are combined. Preferably, the polymerizable moieties of
the crosslinkable silane component and the curable binder precursor
are free-radically-curable.
[0024] A wide range of these materials may be incorporated into the
ceramer composition with beneficial results. Preferably, the
composition includes from about 4 to about 20 parts by weight of
the crosslinkable silane component per 1 part by weight of the
fluoro/silane component. It is additionally preferred that the
composition includes from about 10 to about 80 parts by weight of
the curable binder precursor per 100 parts by weight (including the
weight of the dispersant or other liquid medium) of the colloidal
inorganic oxide. It is also preferred that the composition includes
about 1 to about 20 parts by weight of the crosslinkable silane and
fluoro/silane components per 100 parts by weight of the colloidal
inorganic oxide (again including the weight of the dispersant or
other liquid medium). In embodiments of the invention in which the
colloids are provided as a sol, e.g., an aqueous sol, the sol
preferably includes about 2 to about 50, preferably about 20 to
about 50 percent by weight of the colloids.
[0025] Expressed on a solids basis, the ceramer compositions of the
invention preferably contain about 50 to about 60 weight percent
curable binder precursor and about 35 to about 40 weight percent
colloidal inorganic oxide solids, with the balance (totaling about
5 to about 10 weight percent) being crosslinkable silane and
fluoro/silane.
[0026] Suitable fluoro/silane components include those having at
least one hydrolyzable or hydrolyzed group and a fluorochemical
group. Additionally, suitable fluoro/silane components can be
polymers, oligomers, or monomers and typically contain one or more
fluorochemical moieties that have a fluorinated carbon chain having
from about 3 to about 20 carbon atoms, more preferably from about 6
to about 14 carbon atoms. These fluorochemical moieties can contain
straight chain, branched chain, or cyclic fluorinated alkylene
groups or any combination thereof. The fluorochemical moieties are
preferably free of polymerizable olefinic unsaturation but can
optionally contain catenary (in-chain) heteroatoms such as oxygen,
divalent or hexavalent sulfur, or nitrogen. Perfluorinated groups
are preferred, but hydrogen or halogen atoms can also be present as
substituents, provided that no more than one atom of either is
present for every two carbon atoms.
[0027] A class of useful fluoro/silane components can be
represented by the following general formula:
(S.sub.y).sub.r--W--(R.sub.f).sub.s (1)
[0028] In this formula, S.sub.y represents a hydrolyzable silane
moiety; R.sub.f represents a fluorinated moiety; r is at least 1,
preferably 1 to 4, more preferably 1; s is at least 1, preferably 1
to 4, more preferably 1; and W is a linking group having a valency
of r+s.
[0029] Preferably, each R.sub.f moiety of Formula (1) independently
is a monovalent or divalent, nonionic, perfluoro moiety that may be
linear, branched, or cyclic. If R.sub.f is divalent, both valent
sites of such an R.sub.f moiety preferably are linked to W directly
as illustrated by the following formula: 1
[0030] From Formula (2), it can be seen that each divalent R.sub.f
moiety bonds to two valent sites on W. Accordingly, s of Formula
(1) is incremented by 2 for each such divalent moiety.
[0031] Any of a wide variety of nonionic perfluoro moieties are
suitable for use as R.sub.f. Representative examples of suitable
perfluoro moieties include perfluoroalkyl, perfluoroalkylene,
perfluoroalkoxy, or oxyperfluoroalkylene moieties having 1 to 20,
preferably 3 to 20 carbon atoms. Perfluorinated aliphatic moieties
are the most preferred perfluoro moieties.
[0032] Preferably, each S.sub.y moiety of Formula (1) independently
is a monovalent or divalent, nonionic hydrolyzable silane moiety
that may be linear, branched, or cyclic. The term "hydrolyzable
silane moiety" refers to a hydrolyzable moiety containing at least
one Si atom bonded to at least one halogen atom or at least one
oxygen atom in which the oxygen atom preferably is a constituent of
an acyloxy group or an alkoxy group. Thus, representative examples
of preferred hydrolyzable silane moieties suitable for use as
S.sub.y may be represented by the following formulae: 2
[0033] Generally, R.sup.1 and R.sup.2 independently may be any
nonionic, monovalent substituent other than hydrogen. Additionally,
R.sup.1 and R.sup.2 may be linear, branched, or cyclic. In
embodiments according to Formula (4), R.sup.1 and R.sup.2 may be
co-members of a ring structure. Thus, representative examples of
moieties suitable for use as R.sup.1 and R.sup.2 include any alkyl,
aryl, alkaryl, acyl, alkenyl, arylene or heterocyclic moieties,
combinations thereof, or the like. Any of such moieties, if cyclic,
may include a plurality of rings if desired. For example, aryl
moieties may be aryl-aryl structures. In preferred embodiments,
each of R.sup.1 and R.sup.2 is independently an alkyl group of 1 to
4 carbon atoms or an acyl group such as acetyl (CH.sub.3CO--) or
substituted or unsubstituted benzoyl (C.sub.6H.sub.5CO--). Most
preferably each of R.sup.1 and R .sup.2independently is a lower
alkyl group of 1 to 4 carbon atoms, more preferably CH.sub.3--.
[0034] Z is preferably a halogen atom or --OR.sup.3. In embodiments
in which --OR.sup.3 is an alkoxy group, R.sup.3 preferably is an
alkyl group of 1 to 8, more preferably 1 to 4, and most preferably
1 to 2 carbon atoms. In embodiments in which --OR.sup.3is an
acyloxy group, R.sup.3preferably has the formula --C(O)R.sup.4,
wherein R.sup.4 generally may be any nonionic, monovalent moiety
other than hydrogen. Representative examples of moieties suitable
as R.sup.4include any alkyl, aryl, or alkaryl moieties, and
combinations thereof. Any of such R.sup.4 moieties, if cyclic, may
include a plurality of rings if desired. In preferred embodiments,
R.sup.4 is CH.sub.3--.
[0035] Generally, W of Formula (1) may be any nonionic moiety
capable of linking the at least one S.sub.y moiety and the at least
one R.sub.f moiety together. Preferably, W contains a backbone of 4
to 30 atoms and may contain one or more moieties such as an
alkylene moiety, an ether moiety, an ester moiety, a urethane
moiety, a carbonate moiety, an imide moiety, an amide moiety, an
aryl moiety, an alkaryl moiety, an alkoxyaryl moiety, sulfonyl,
nitrogen, oxygen, combinations of these, and the like.
[0036] A preferred class of compounds according to Formula (1) is
represented by any of the formulae 3
[0037] wherein n is 1 to 20, preferably 3 to 20; R.sup.7 is a
monovalent moiety, preferably an aryl, alkyl, or alkyaryl moiety,
more preferably an alkyl moiety of 1 to 4 carbon atoms; X.sup.1 is
an alkylene group of 1 to 10 carbon atoms, and Z, R.sup.1, R.sup.2
and R.sup.3 are as defined above.
[0038] Representative specific examples of preferred compounds
according to Formula (1) include the following compounds:
[0039]
C.sub.5F.sub.11CH.sub.2OCH.sub.2CH.sub.2CH.sub.2Si(OCH.sub.2CH.sub.-
3).sub.3
[0040]
C.sub.7F.sub.15CH.sub.2OCH.sub.2CH.sub.2CH.sub.2Si(OCH.sub.2CH.sub.-
3).sub.3
[0041]
C.sub.7F.sub.15CH.sub.2OCH.sub.2CH.sub.2CH.sub.2SiCl.sub.3
[0042]
C.sub.8F.sub.17CH.sub.2CH.sub.2OCH.sub.2CH.sub.2CH.sub.2SiCl.sub.3
[0043]
C.sub.18F.sub.37CH.sub.2OCH.sub.2CH.sub.2CH.sub.2CH.sub.2SiCl.sub.3
[0044]
CF.sub.3CF(CF.sub.2Cl)CF.sub.2CF.sub.2SO.sub.2N(CH.sub.3)CH.sub.2CH-
.sub.2CH.sub.2SiCl.sub.3
[0045]
C.sub.8F.sub.17SO.sub.2N(CH.sub.2CH.sub.3)CH.sub.2CH.sub.2CH.sub.2S-
i(OCH.sub.3).sub.3
[0046]
C.sub.8F.sub.17SO.sub.2N(CH.sub.3)CH.sub.2CH.sub.2CH.sub.2Si(OCH.su-
b.3).sub.3
[0047]
C.sub.8F.sub.17SO.sub.2N(CH.sub.2CH.sub.3)CH.sub.2CH.sub.2CH.sub.2S-
i(OCH.sub.3).sub.av1.9[(OCH.sub.2CH.sub.2).sub.av6.1OCH.sub.3].sub.av1.1
[0048]
C.sub.7F.sub.15CH.sub.2O(CH.sub.2).sub.3Si(OCH.sub.2CH.sub.2OCH.sub-
.2CH.sub.2OH).sub.3
[0049] C.sub.7F.sub.15CH.sub.2CH.sub.2Si(CH.sub.3)Cl.sub.2
[0050] C.sub.8F.sub.17CH.sub.2CH2SiCl.sub.3
[0051]
C.sub.13SiCH.sub.2CH.sub.2CH.sub.2OCH.sub.2(OCF.sub.2CF.sub.2).sub.-
8CH.sub.2OCH.sub.2CH.sub.2CH.sub.2SiCl.sub.3
[0052]
CF.sub.3O(CF.sub.2CF(CF.sub.3)O).sub.4CF.sub.2C(=O)NHCH.sub.2CH.sub-
.2CH.sub.2Si(OC.sub.2H.sub.5).sub.3
[0053]
CF.sub.3O(C.sub.3F.sub.6O).sub.4(CF.sub.2O).sub.3CF.sub.2CH.sub.2OC-
(=O)NHCH.sub.2CH.sub.2CH.sub.2Si(OCH.sub.3).sub.3
[0054]
Cl.sub.3SiCH.sub.2CH.sub.2OCH.sub.2(CF.sub.2CF.sub.2O).sub.8(CF.sub-
.2O).sub.4CF.sub.2CH.sub.2CH.sub.2CH.sub.2SiCl.sub.3
[0055] C.sub.8F.sub.17CONHC.sub.6H.sub.4Si(OCH.sub.3).sub.3
[0056]
C.sub.8F.sub.17SO.sub.2N(CH.sub.2CH.sub.3)CH.sub.2CH.sub.2CH.sub.2S-
i(OCH.sub.3).sub.av1(OCH.sub.2CH.sub.2(OCH.sub.2CH.sub.2).sub.2OCH.sub.3).-
sub.av2
[0057] A particularly preferred embodiment of a fluoro/silane
component according to Formula (1), for example, is represented by
the formula 4
[0058] The compound according to Formula (11) is commercially
available from Minnesota Mining and Manufacturing Company, St.
Paul, Minn. under the trade designation FC405. Methods of making
such a compound and fluoro/silane compounds in general are
described in U.S. Pat. No. 3,787,467 to Lucking et al., the
disclosure of which is herein incorporated by reference.
[0059] Useful fluoro/silane components can be prepared, e.g., by
reacting (a) at least one fluorochemical compound having at least
one reactive functional group with (b) a functionalized silane
having from one to about three hydrolyzable groups and at least one
alkyl, aryl, or alkoxyalkyl group that is substituted by at least
one functional group that is capable of reacting with the
functional group of the fluorochemical compound(s). Such methods
are disclosed in U.S. Pat. No. 5,274,159 (Pellerite et al.).
[0060] Crosslinkable silane components suitable for use in the
ceramer composition of the present invention are commercially
available from numerous sources. Generally, suitable crosslinkable
silane components contain at least one hydrolyzable silane moiety
and at least one polymerizable moiety other than a silane moiety.
The polymerizable moiety preferably contains either (meth)acrylate,
allyl, styryl, amino, or epoxy functionalities, while the
hydrolyzable silane group is usually an alkoxy silyl moiety
(generally methoxy or ethoxy) which serves as a binding site to
hydroxy-functional inorganic substrates via displacement of the
alkoxy groups. Additional information concerning crosslinkable
silane components may be found in the book by E. P. Pleuddeman
("Silane coupling Agents", Plenum Press, New York, 1982, pp. 20-23
and 97) as well as in technical reports by S. Sterman and J. G.
Marsden entitled "Theory of Mechanisms of Silane Coupling Agents in
Glass Reinforced and Filled Thermoplastic and Thermosetting Resin
Systems", Union Carbide Corporation, New York, and "A Guide to Dow
Coming Silane Coupling Agents", Dow Corning Corporation, 1985, pp.
2-13, the disclosures of which are incorporated by reference
herein.
[0061] Crosslinkable silane components suitable for use in the
ceramer compositions of the present invention may be polymers,
oligomers, or monomers and may preferably be represented by the
formula
(S.sub.y).sub.q--W.sup.o--(R.sub.c).sub.p (12)
[0062] In Formula (12), S.sub.y represents a hydrolyzable silane
moiety as defined above with respect to Formulae (1) and (2);
R.sub.c is a moiety containing curable functionality, preferably
free-radically-curable functionality; q is at least 1, preferably 1
to 4, more preferably 1; p is at least 1, preferably 1 to 4, more
preferably 1; and W.sup.o is a linking group having a valency of
q+p. Compounds according to Formula (12) and methods of making such
compounds are described in U.S. Pat. No. 5,314,980, the disclosure
of which is incorporated by reference herein.
[0063] Generally, W.sup.o of Formula (12) may be any nonionic
moiety capable of linking the at least one S.sub.y moiety and the
at least one R.sub.c moiety together. Preferably, W.sup.o has a
backbone of 4 to 30 atoms and may contain one or more moieties such
as an alkylene moiety, an ether moiety, an ester moiety, a urethane
moiety, a carbonate moiety, an imide moiety, an amide moiety, an
aryl moiety, an alkaryl moiety, an alkoxyaryl moiety, arylsulfonyl
moiety, nitrogen, oxygen, combinations of these, and the like.
[0064] Embodiments of compounds according to Formula (12) in the
form of silane functional (meth)acrylates include, for example,
3-(methacryloxy)propyl trimethoxysilane, 3-acryloxypropyl
trimethoxysilane, 3-(methacryloxy)propyltriethoxysilane,
3-(methacryloxy)propylmethyldimethoxysilane,
3-(acryloxypropyl)methyldime- thoxysilane,
3-(methacryloxy)propyldimethylethoxysilane,
3-(methacryloxy)methyltriethoxysilane,
3-(methacryloxy)methyltrimethoxysi- lane,
3-(methacryloxy)propyldimethylethoxysilane, 3-methacryloxypropenyl
trimethoxysilane, vinyldimethylethoxysilane,
vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane,
vinyltriacetoxysilane, vinyltriethoxysilane,
vinyltriisopropoxysilane, vinyltrimethoxysilane,
vinyltriphenoxysilane, vinyltri-t-butoxysilane,
vinyltris-isobutoxysilane, vinyltriisopropenoxysilane,
vinyltris(2-methoxyethoxy)silane, and mixtures thereof. Of these,
3-(methacryloxy)propyl trimethoxysilane, 3-acryloxypropyl
trimethoxysilane, 3-(methacryloxy)propylmethyldimethoxys- ilane and
3-(methacryloxy)propyldimethylethoxysilane are preferred.
Furthermore, embodiments of crosslinkable silane components
according to Formula (18) in the form of silane functional
polyolefins can be produced from commercially available starting
materials by any of several methods.
[0065] Exemplary crosslinkable silane components are described in
the above-mentioned Pleuddeman reference and in U.S. Pat. Nos.
4,491,508 and 4,455,205 to Olsen et al.; U.S. Pat. Nos. 4,478,876
and 4,486,504 to Chung; and U.S. Pat. No. 5,258,225 to Katsamberis,
all of which are incorporated herein by reference.
[0066] In the practice of the present invention,
free-radically-curable functionality refers to functional groups
directly or indirectly pendant from a monomer, oligomer, or polymer
backbone (as the case may be) that participate in crosslinking or
polymerization reactions upon exposure to a suitable source of
radiant (e.g., UV or thermal) curing energy. Such functionality
generally includes not only groups that crosslink via a cationic
mechanism upon radiation exposure but also groups that crosslink
via a free radical mechanism. Representative examples of radiation
polymerizable moieties suitable in the practice of the present
invention include epoxy groups, (meth)acrylate groups, olefinic
carbon-carbon double bonds, allylether groups, styrene groups,
(meth)acrylamide groups, combinations of these, and the like.
Representative examples of curing energy include electromagnetic
energy (e.g., infrared energy, microwave energy, visible light,
ultraviolet light, and the like), accelerated particles (e.g.,
electron beam energy), or energy from electrical discharges (e.g.,
coronas, plasmas, glow discharge, or silent discharge).
[0067] The colloidal inorganic oxides for use in the present
invention include particles, powders, and oxides in solution. The
colloidal inorganic oxides are desirably substantially spherical in
shape, and relatively uniform in size (e.g., they have a
substantially monodisperse size distribution or a polymodal
distribution obtained by blending two or more substantially
monodisperse distributions). It is further preferred that the
colloidal inorganic oxides be and remain substantially
non-aggregated (substantially discrete), as colloidal aggregation
can result in precipitation, gellation, or a dramatic increase in
sol viscosity and can reduce both adhesion to the substrate and
optical clarity. Finally, it is preferable that the colloidal
inorganic oxides be characterized by an average particle diameter
of about 1 nanometer to about 200 nanometers, preferably from about
1 nanometer to about 100 nanometers, more preferably from about 2
nanometers to about 75 nanometers. These size ranges facilitate
ease of dispersion of the particles into coatable ceramer
compositions and provide ceramer coatings that are smoothly
surfaced and optically clear. Average particle size of the colloids
can be measured using transmission electron microscopy to count the
number of particles of a given diameter.
[0068] A wide range of colloidal inorganic oxides can be used in
the present invention. Representative examples include colloidal
titania, colloidal alumina, colloidal zirconia, colloidal vanadia,
colloidal chromia, colloidal iron oxide, colloidal antimony oxide,
colloidal tin oxide, and mixtures thereof. The colloidal inorganic
oxide can be a single oxide such as silica, a combination of oxides
such as silica and aluminum oxide, or a core of an oxide of one
type (or a core of a material other than a metal oxide) on which is
deposited an oxide of another type.
[0069] In one preferred embodiment, for example, the inorganic
oxide may be a mixture containing a major amount of a first or
primary inorganic oxide, e.g., silica, and a minor amount of a
second or additive oxide, preferably an aluminum oxide such as a
sodium aluminate. As used herein, "major amount" means that the
inorganic oxide includes a sufficient amount of the primary oxide
(preferably at least about 80% by weight, more preferably at least
about 95% by weight, and most preferably at least about 98% by
weight) such that the composite properties of the resultant ceramer
are primarily due to such primary oxide. "Minor amount" means that
the inorganic oxides include a sufficient amount of the additive
oxide to enhance at least one property of the resultant uncured or
cured ceramer composition.
[0070] It has now been discovered that it is much easier
homogeneously to disperse inorganic oxides in uncured ceramer
compositions or within sols from which the ceramers are to be
derived when the inorganic oxide includes both a primary inorganic
oxide and at least one additive inorganic oxide. For example, cured
ceramer coatings incorporating silica and aluminum oxide particles
have shown better abrasion resistance and improved processability
than otherwise identical ceramer coatings having no additive
oxide.
[0071] The optimum amount of an additive oxide to be incorporated
into a ceramer composition will depend upon a number of factors
including the type(s) of additive oxide(s) being used, the desired
end use of the ceramer composition, and the like. Generally, if too
little of an additive oxide is used, little benefit will be
observed. On the other hand, if too much of an additive oxide is
used, then the resultant cured ceramer coating may be hazier than
desired, and abrasion resistance may be reduced. As one suggested
guideline for preferred embodiments in which the corresponding
cured ceramer coating is desired to be optically clear and abrasion
resistant, the ceramer composition may include about 100 parts by
weight of silica and about 0.01 to about 10, preferably about 1 to
about 2 parts by weight of an oxide other than silica, preferably
an aluminum oxide.
[0072] The colloidal inorganic oxide is desirably provided in the
form of a sol (e.g., a colloidal dispersion of inorganic oxide
particles in liquid media), especially sols of amorphous silica.
Unlike other forms in which the colloidal inorganic oxide particles
may be supplied (e.g., fumed silica which contains irregular
aggregates of colloidal particles), colloids of such sols tend to
be substantially monodisperse in size and shape and thus enable the
preparation of ceramer compositions exhibiting good optical
clarity, smoothness, and surprisingly good adhesion to substrates.
Preferred sols generally contain from about 2 to about 50 weight
percent, preferably from about 25 to about 45 weight percent, of
colloidal inorganic oxide.
[0073] Sols useful in the practice of the present invention may be
prepared by methods well known in the art. For example, silica
hydrosols containing from about 2 to about 50 percent by weight of
silica in water are generally useful and can be prepared, e.g., by
partially neutralizing an aqueous solution of an alkali metal
silicate with base to a pH of about 8 or about 9 (such that the
resulting sodium content of the solution is less than about 1
percent by weight based on sodium oxide). Sols useful in the
practice of the present invention may also be prepared in a variety
of forms, including hydrosols (where water serves as the liquid
medium), organosols (where organic liquids are used as the liquid
medium), and mixed sols (where the liquid medium contains both
water and an organic liquid). See, e.g., the descriptions of the
techniques and forms given in U.S. Pat. Nos. 2,801,185 (Iler) and
4,522,958 (Das et al.), whose descriptions are incorporated herein
by reference, as well as those given by R. K. Iler in The Chemistry
of Silica, John Wiley & Sons, New York (1979).
[0074] Due to their low cost, and environmental considerations,
silica hydrosols (also known as aqueous silica sols) are preferred
for use in preparing the ceramer compositions of the invention. The
surface chemistry of hydrosols makes them particularly well suited
for use in the ceramer compositions of the present invention. For
example, when colloidal inorganic oxide particles are dispersed in
water, the sol is stabilized to some degree due to common
electrical charges that develop on the surface of each particle.
The common electrical charges tend to promote dispersion rather
than agglomeration or flocculation, because the similarly charged
particles repel one another.
[0075] Hydrosols are commercially available in both acidic and
basic forms and with a variety of particle sizes and concentrations
under such trademarks as "LUDOX" (E. I. DuPont de Nemours and Co.,
Inc. Wilmington, Del.), "NYACOL" (Nyacol Co., Ashland, Mass.), and
"NALCO" (Nalco Chemical Co., Oak Brook, Ill.). Additional examples
of suitable colloidal silicas are described in U.S. Pat. No.
5,126,394, incorporated herein by reference. Although either acidic
or basic sols are suitable for use in the ceramer compositions of
the present invention, it is desirable to match the pH of the sol
with that of the curable binder precursor in order to minimize the
tendency of the colloids of the sol to flocculate when the sol and
the curable binder precursor are combined. For example, if the sol
is acidic, the curable binder precursor also preferably is acidic.
On the other hand, if the sol is basic, the curable binder
precursor also preferably is basic.
[0076] In one preferred ceramer embodiment of the present invention
to be derived from an aqueous silica sol, it may be desirable to
add a minor amount of a water soluble compound such as sodium
aluminate (NaAlO.sub.2) to the sol. Addition of a compound such as
sodium aluminate provides a sol, and corresponding ceramer
composition, that include both silica colloids and aluminum oxides.
Use of an additive oxide such as aluminum oxide makes it easier to
obtain homogeneous ceramer compositions, improved abrasion
resistance, and improved adhesion in wet or dry environments. This
is believed to be attributable to the enhanced hydrolytic stability
of ceramer composites including silica colloids and aluminum
oxides.
[0077] The sols may include counterions in order to counter the
surface charge of the colloids. Depending upon pH and the kind of
colloids being used, the surface charges on the colloids can be
negative or positive. Thus, either cations or anions are used as
counter ions. Examples of cations suitable for use as counter ions
for negatively charged colloids include Na.sup.+, K.sup.+,
Li.sup.+, a quaternary ammonium cation such as NR'.sup.4+, (wherein
each R' may be any monovalent moiety, but is preferably H or lower
alkyl such as CH.sub.3), combinations of these, and the like.
Examples of counter anions suitable for use as counter ions for
positively charged colloids include HSO.sub.3.sup.-- and
R--COO.sup.-- where R represents an alkyl carboxylate.
[0078] As one option, suitable curable binder precursors can be
selected from any curable thermoplastic or thermosetting polymer
that contains moieties capable of crosslinking with the R.sub.c
(refer to Formula (12)) moiety of the crosslinkable silane
component. Examples of such polymers include polyurethane,
polycarbonate, polyester, polyamide, polyimide, phenoxy, phenolic
resin, cellulosic resin, polystyrene, styrene copolymer,
poly(meth)acrylate, epoxy, silicone resin, combination of these,
and the like. As another option, the curable binder precursor can
be in the form of prepolymeric materials which can be copolymerized
or homopolymerized in situ after the ceramer composition has been
coated onto a substrate.
[0079] As one example of an approach using prepolymeric materials,
the curable binder precursor may contain one or more
free-radically-curable monomers, oligomers, polymers, or
combinations of these having pendant free-radically-curable
functionality which allows the materials to polymerize or crosslink
using a source of curing energy such as electron beam radiation,
ultraviolet radiation, visible light, and the like. Preferred
free-radically-curable monomers, oligomers, or polymers each
include one or more free-radically-curable, carbon-carbon double
bonds such that the average functionality of such materials is
greater than one free-radically-curable carbon-carbon double bond
per molecule. Materials having such moieties are capable of
copolymerization or crosslinking with each other via such
carbon-carbon double bond functionality.
[0080] Generally, the term "monomer" as used herein refers to a
single, one unit molecule capable of combination with itself or
other monomers to form oligomers or polymers. The term "oligomer"
refers to a compound that is a combination of 2 to 20 monomers. The
term "polymer" refers to a compound that is a combination of 21 or
more monomers.
[0081] Generally, ceramer compositions including oligomeric or
polymeric free-radically-curable binder precursors tend to have
higher viscosities than ceramer compositions including only
monomeric free-radically-curable binder precursors. Accordingly, in
applications involving techniques such as spin coating or the like
in which it is desirable for the ceramer composition to have a low
viscosity, e.g., a viscosity of less than 200 centipoise measured
at 25.degree. C. using a Brookfield viscometer with any suitable
spindle operated at a spindle speed in the range from 20 to 50 rpm,
it is preferred that at least 50%, by weight, more preferably
substantially all, of any prepolymeric binder precursors are
monomeric free-radically-curable binder precursors.
[0082] Free-radically-curable monomers suitable in the practice of
the present invention are preferably selected from combinations of
mono, di, tri, tetra, penta, and hexafunctional
free-radically-curable monomers. Various amounts of the mono, di,
tri, tetra, penta, and hexafunctional free-radically-curable
monomers may be incorporated into the present invention, depending
upon the desired properties of the final ceramer coating.
[0083] For example, in order to provide ceramer coatings with
higher levels of abrasion and impact resistance, it is desirable
for the ceramer composition to include one or more multifunctional
free-radically-curable monomers, and preferably at least both di-
and tri-functional free-radically-curable monomers, such that the
free-radically-curable monomers incorporated into the ceramer
composition have an average free-radically-curable functionality
per molecule of greater than 1. Preferred ceramer compositions of
the present invention may include about 1 to about 35 parts by
weight of monofunctional free-radically-curable monomers, 0 to
about 75 parts by weight of difunctional free-radically-curable
monomers, about 1 to about 75 parts by weight of trifunctional
free-radically-curable monomers, 0 to about 75 parts by weight of
tetrafunctional free-radically-curable monomers, 0 to about 75
parts by weight of pentafunctional free-radically-curable monomers,
and 0 to about 75 parts by weight of hexafunctional
free-radically-curable monomers, subject to the proviso that the
free-radically-curable monomers have an average functionality of
greater than 1, preferably 1.1 to 4, more preferably 1.5 to 3.
[0084] One representative class of monofunctional
free-radically-curable monomers suitable in the practice of the
present invention includes compounds in which a carbon-carbon
double bond is directly or indirectly linked to an aromatic ring.
Examples of such compounds include styrene, alkylated styrene,
alkoxy styrene, free-radically-curable naphthalene, alkylated vinyl
naphthalene, alkoxy vinyl naphthalene, combinations of these, and
the like. Another representative class of monofunctional,
free-radically-curable monomers includes compounds in which a
carbon-carbon double bond is attached to an cycloaliphatic,
heterocyclic, or aliphatic moiety such as 5-vinyl-2-norbomene,
4-vinyl pyridine, 2-vinyl pyridine, 1-vinyl-2-pyrrolidinone,
1-vinyl caprolactam, 1-vinylimidazole, N-vinyl formamide, and the
like.
[0085] Another representative class of such monofunctional
free-radically-curable monomers include (meth)acrylate functional
monomers that incorporate moieties of the formula: 5
[0086] wherein R.sup.8 is a monovalent moiety, such as hydrogen,
halogen, methyl, or the like. Representative examples of such
monomers include, linear, branched, or cycloaliphatic esters of
(meth)acrylic acid containing from 1 to 20, preferably 1 to 8,
carbon atoms, such as methyl (meth)acrylate, n-butyl
(meth)acrylate, t-butyl (meth)acrylate, ethyl (meth)acrylate,
isopropyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; vinyl
esters of alkanoic acids wherein the alkyl moiety of the alkanoic
acids contain 2 to 20, preferably 2 to 4, carbon atoms and may be
linear, branched, or cyclic; isobomyl (meth)acrylate; vinyl
acetate; allyl (meth)acrylate, and the like.
[0087] Such (meth)acrylate functional monomers may also include
other kinds of reactive functionality such as hydroxyl
functionality, nitrile functionality, epoxy functionality,
carboxylic functionality, thiol functionality, amine functionality,
sulfonyl functionality, combinations of these, and the like.
Representative examples of such free-radically-curable compounds
include glycidyl (meth)acrylate, (meth)acrylonitrile,
.beta.-cyanoethyl-(meth)acrylate, 2-cyanoethoxyethyl
(meth)acrylate, p-cyanostyrene, p-(cyanomethyl)styrene, an ester of
an .alpha.,.beta.-unsaturated carboxylic acid with a diol, e.g.,
2-hydroxyethyl (meth)acrylate, or 2-hydroxypropyl (meth)acrylate;
1,3-dihydroxypropyl-2-(meth)acrylate;
2,3-dihydroxypropyl-1-(meth)acrylat- e; an adduct of an
.alpha.,.beta.-unsaturated carboxylic acid with caprolactone; an
alkanol vinyl ether such as 2-hydroxyethyl vinyl ether;
4-vinylbenzyl alcohol; allyl alcohol; p-methylol styrene,
(meth)acryloyloxyethyl trimethyl ammonium chloride,
(meth)acrylamidopropyl trimethylammonium chloride, vinylbenzyl
trimethylammonium chloride, 2-hydroxy-3-allyloxypropyl
trimethylammonium chloride, (meth)acryloxypropyl
dimethylbenzylammonium chloride, dimethylaminoethyl (meth)acrylate,
vinylbenzyl trimethylammonium chloride,
N-(3-sulfopropyl)-N-(meth)acryloxyethyl-N,N-dimethylammonium
betaine, 2-[(meth)acryloxy]ethyl trimethylammonium methosulfate,
N-(3-sulfopropyl)-N-(meth)acrylamidopropyl-N, N-dimethylammonium
betaine, N,N-dimethylamino (meth)acrylate, (meth)acryloyloxyethyl
acid phosphate, (meth)acrylamidopropyl sodium sulfonate, sodium
styrene sulfonate, styrene sulfonic acid, (meth)acrylic acid,
maleic acid, fumaric acid, maleic anhydride, vinyl sulfonic acid,
2-(meth)acrylamide-2-methyl-1-prop- anesulfonic acid, maleic
anhydride, mixtures thereof, and the like.
[0088] Another class of monofunctional, free-radically-curable
monomers that may optionally be used in the practice of the present
invention, but is in no way required, includes one or more
N,N-disubstituted (meth)acrylamides. Use of an N,N-disubstituted
(meth)acrylamide provides numerous advantages. For example, the use
of this kind of monomer provides ceramer coatings which show
improved adhesion to polycarbonate substrates. Further, use of this
kind of monomer also provides ceramer coatings with improved
weatherability and toughness. Preferably, the N,N-disubstituted
(meth)acrylamide has a molecular weight in the range from about 99
to about 500, preferably from about 99 to about 200, in order to
minimize the tendency, if any, of the colloidal inorganic oxide to
flocculate and precipitate out of the ceramer composition.
[0089] The N,N-disubstituted (meth)acrylamide monomers generally
have the formula: 6
[0090] wherein R.sup.9 and R.sup.10 are each independently
hydrogen, a (C.sub.1-C.sub.8)alkyl group (linear, branched, or
cyclic) optionally having hydroxy, halide, carbonyl, and amido
functionalities, a (C.sub.1-C.sub.8)alkylene group optionally
having carbonyl and amido functionalities, a
(C.sub.1-C.sub.4)alkoxymethyl group, a (C.sub.4-C.sub.18)aryl or
heteroaryl group, a (C.sub.1-C.sub.3)alk(C.sub.- 4-C.sub.18)aryl
group, or a (C.sub.4-C.sub.18)heteroaryl group; with the proviso
that only one of R.sup.9 and R.sup.10 is hydrogen; and R.sup.11 is
hydrogen, a halogen, or a methyl group. Preferably, R.sup.9 is a
(C.sub.1-C.sub.4)alkyl group; R.sup.10 is a (C.sub.1-C.sub.4)alkyl
group; and R.sup.11 is hydrogen, or a methyl group. R.sup.9 and
R.sup.10 can be the same or different. More preferably, each of
R.sup.9 and R.sup.10 is CH.sub.3, and R.sup.11 is hydrogen.
[0091] Examples of such suitable (meth)acrylamides are
N-(3-bromopropion-amidomethyl) acrylamide, N-tert-butylacrylamide,
N,N-dimethylacrylamide, N,N-diethylacrylamide,
N-(5,5-dimethylhexyl)acryl- amide,
N-(1,1-dimethyl-3-oxobutyl)acrylamide, N-(hydroxymethyl)acrylamide,
N-(isobutoxymethyl)acrylamide, N-isopropylacrylamide,
N-methylacrylamide, N-ethylacrylamide, N-methyl-N-ethylacrylamide,
N-(fluoren-2-yl)acrylamide- , N-(2-fluorenyl)-2-methylacrylamide,
2,3-bis(2-furyl)acrylamide, N,N'-methylene-bis acrylamide. A
particularly preferred (meth)acrylamide is N,N-dimethyl
(meth)acrylamide.
[0092] Other examples of free-radically-curable monomers include
alkenes such as ethene, 1-propene, 1-butene, 2-butene (cis or
trans), compounds including an allyloxy moiety, and the like.
[0093] Multifunctional (meth)acrylate compounds suitable for use in
the curable binder precursor are commercially available from a
number of different suppliers. Alternatively, such compounds can be
prepared using a variety of well known reaction schemes. For
example, according to one approach, a (meth)acrylic acid or acyl
halide or the like is reacted with a polyol having at least two,
preferably 2 to 6, hydroxyl groups. This approach can be
represented by the following schematic reaction scheme which, for
purposes of illustration, shows the reaction between acrylic acid
and a triol: 7
[0094] This reaction scheme as illustrated provides a trifunctional
acrylate. To obtain di, tetra, penta, or hexa functional compounds,
corresponding diol, tetrols, pentols, and hexols could be used in
place of the triol, respectively.
[0095] According to another approach, a hydroxy or amine functional
(meth)acrylate compound or the like is reacted with a
polyisocyanate, or isocyanurate, or the like having 2 to 6 NCO
groups or the equivalent. This approach can be represented by the
following schematic reaction scheme which, for purposes of
illustration, shows the reaction between hydroxyethyl acrylate and
a triisocyanate: 8
[0096] wherein each W is 9
[0097] This reaction scheme as illustrated provides a trifunctional
(meth)acrylate. To obtain di, tetra, penta, or hexa functional
compounds, corresponding multifunctional isocyanates could be used
in place of the triisocyanate, respectively.
[0098] A preferred class of multifunctional (meth)acryl functional
compounds includes one or more multifunctional, ethylenically
unsaturated esters of (meth)acrylic acid and may be represented by
the following formula: 10
[0099] wherein R.sup.12 is hydrogen, halogen or a
(C.sub.1-C.sub.4)alkyl group; R.sup.13 is a polyvalent organic
group having m valencies and can be cyclic, branched, or linear,
aliphatic, aromatic, or heterocyclic, having carbon, hydrogen,
nitrogen, nonperoxidic oxygen, sulfur, or phosphorus atoms; and z
is an integer designating the number of acrylic or methacrylic
groups in the ester and has a value of 2 to 7. Preferably, R.sup.12
is hydrogen, methyl, or ethyl, R.sup.13 has a molecular weight of
about 14 to 100, and m has a value of 2 to 6. More preferably, z
has a value of 2 to 5, most preferably 3 to 4. Where a mixture of
multifunctional acrylates or methacrylates are used, z preferably
has an average value of about 1.05 to 3.
[0100] Specific examples of suitable multifunctional ethylenically
unsaturated esters of (meth)acrylic acid are the polyacrylic acid
or polymethacrylic acid esters of polyhydric alcohols including,
for example, the diacrylic acid and dimethylacrylic acid ester of
aliphatic diols such as ethyleneglycol, triethyleneglycol,
2,2-dimethyl-1,3-propane- diol, 1,3-cyclopentanediol,
1-ethoxy-2,3-propanediol, 2-methyl-2,4-pentanediol,
1,4-cyclohexanediol, 1,6-hexamethylenediol, 1,2-cyclohexanediol,
1,6-cyclohexanedimethanol; the triacrylic acid and trimethacrylic
acid esters of aliphatic triols such as glycerin,
1,2,3-propanetrimethanol, 1,2,4-butanetriol, 1,2,5-pentanetriol,
1,3,6-hexanetriol, and 1,5,10-decanetriol; the triacrylic acid and
trimethacrylic acid esters of tris(hydroxyethyl) isocyanurate; the
tetraacrylic and tetramethacrylic acid esters of aliphatic
tetraols, such as 1,2,3,4-butanetetraol,
1,1,2,2,-tetramethylolethane, 1,1,3,3-tetramethylolpropane, and
pentaerythritol triacrylate; the pentaacrylic acid and
pentamethacrylic acid esters of aliphatic pentols such as adonitol;
the hexaacrylic acid and hexamethacrylic acid esters of hexanols
such as sorbitol and dipentaerythritol; the diacrylic acid and
dimethacrylic acid esters of aromatic diols such as resorcinol,
pyrocatechol, bisphenol A, and bis(2-hydroxyethyl) phthalate; the
trimethacrylic acid ester of aromatic triols such as pyrogallol,
phloroglucinol, and 2-phenyl-2,2-dimethylolethanol; and the
hexaacrylic acid and hexamethacrylic acid esters of dihydroxy ethyl
hydantoin; and mixtures thereof.
[0101] In addition to the fluoro/silane component, the
crosslinkable silane component, the curable binder precursor, and
the colloidal inorganic oxide, the ceramer composition may further
include a solvent and other optional additives. For example, if
desired, the ceramer composition may include a solvent to reduce
the viscosity of the ceramer composition in order to enhance the
ceramer coating characteristics. The appropriate viscosity level
depends upon various factors such as the coating thickness,
application technique, and the type of substrate material onto
which the ceramer composition is applied. In general, the viscosity
of the ceramer composition at 25.degree. C. is about 1 to about 200
centipoise, preferably about 3 to about 75 centipoise, more
preferably about 4 to about 50 centipoise, and most preferably
about 5 to about 20 centipoise when measured using a Brookfield
viscometer with a No. 2 cv spindle at a spindle speed of 20 rpm. In
general, sufficient solvent is used such that the solids content of
the ceramer composition is about 5 to about 95%, preferably about
10 to about 50%, more preferably about 15 to about 30%, by weight
solids.
[0102] The solvent is selected to be compatible with the other
components included in the ceramer composition. As used in this
context, "compatible" means that there is minimal phase separation
between the solvent and the other components. Additionally, the
solvent should be selected such that the solvent does not adversely
affect the curing properties of the ceramer composition or attack
the material of the substrate. Furthermore, the solvent should be
selected such that it has an appropriate drying rate. That is, the
solvent should not dry too slowly, which would slow down the
process of making a coated substrate. It should also not dry too
quickly, which could cause defects such as pin holes or craters in
the resultant ceramer coating. The solvent can be an organic
solvent, water, or combinations thereof. Representative examples of
suitable solvents include lower alcohols such as ethanol, methanol,
isopropyl alcohol, and n-butanol; ketones such as methyl ethyl
ketone and methyl isobutyl ketone; glycols; glycol ethers;
combinations thereof, and the like. Most preferably, the solvent is
isopropanol. Using the procedure described below for making a
ceramer composition, the solvent may also include a small amount,
e.g. about 2% by weight, of water.
[0103] The ceramer compositions of the present invention also may
include a leveling agent to improve the flow or wetting of the
ceramer composition onto the substrate. If the ceramer composition
does not properly wet the substrate, this can lead to visual
imperfections (e.g., pin holes or ridges) in the ceramer coating.
Examples of leveling agents include, but are not limited to,
alkylene oxide terminated polysiloxanes such as that available
under the trade designation "DOW 57" (a mixture of dimethyl-,
methyl-, and (polyethylene oxide acetate-capped) siloxane) from Dow
Coming, Midland, Mich., and fluorochemical surfactants such as
those available under the trade designations "FC430" and "FC43 1 "
from Minnesota Mining and Manufacturing Company Co., St. Paul,
Minn.. The ceramer composition can include an amount of a leveling
agent effective to impart the desired result. Preferably, the
leveling agent is present in an amount up to about 3% by weight,
and more preferably about 0.5 to about 1%, based on the total
weight of the ceramer composition solids. It should be understood
that combinations of different leveling agents can be used if
desired.
[0104] During the manufacture of an abrasion resistant, ceramer
coating of the type including a free-radically-curable binder
precursor, the coated ceramer composition preferably is exposed to
an energy source, e.g., radiation, which initiates the curing
process of the ceramer coating. This curing process typically
occurs via a free radical mechanism, which can require the use of a
free radical initiator (simply referred to herein as an initiator,
e.g., a photoinitiator or a thermal initiator) depending upon the
energy source used. If the energy source is an electron beam, the
electron beam generates free radicals and no initiator is typically
required. If the energy source is ultraviolet light, or visible
light, an initiator is often required. When the initiator is
exposed to one of these energy sources, the initiator generates
free radicals, which then initiates the polymerization and
crosslinking.
[0105] Examples of suitable free radical initiators that generate a
free radical source when exposed to thermal energy include, but are
not limited to, peroxides such as benzoyl peroxide, azo compounds,
benzophenones, and quinones. Examples of photoinitiators that
generate a free radical source when exposed to visible light
radiation include, but are not limited to, camphorquinones/alkyl
amino benzoate mixtures. Examples of photoinitiators that generate
a free radical source when exposed to ultraviolet light include,
but are not limited to, organic peroxides, azo compounds, quinones,
benzophenones, nitroso compounds, acryl halides, hydrozones,
mercapto compounds, pyrylium compounds, triacrylimidazoles,
bisimidazoles, chloroalkytriazines, benzoin, benzoin methyl ether,
benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl
ethers and methylbenzoin, diketones such as benzil and diacetyl,
phenones such as acetophenone, 2,2,2-tri-bromo-1-phenylethanone,
2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone,
2,2,2,-tribromo-1(2-nitrophenyl)ethanone, benzophenone,
4,4-bis(dimethyamino)benzophenone, and acyl phosphates. Examples of
commercially available ultraviolet photoinitiators include those
available under the trade designations "IRGACURE.TM. 184"
(1-hydroxycyclohexyl phenyl ketone), "IRGACURE.TM. 361" and
"DAROCUR.TM. 1173" (2-hydroxy-2-methyl-1-phenyl-propan-1-one) from
Ciba-Geigy. Typically, if used, an amount of an initiator is
included in the ceramer composition to effect the desired level and
rate of cure. Preferably, the initiator is used in an amount of
about 0.1 to about 10%, and more preferably about 2 to about 4% by
weight, based on the total weight of the ceramer composition
without solvent. It should be understood that combinations of
different initiators can be used if desired.
[0106] In addition to the initiator, the ceramer composition of the
present invention can include a photosensitizer. The
photosensitizer aids in the formation of free radicals that
initiate curing of the curable binder precursors, especially in an
air atmosphere. Suitable photosensitizers include, but are not
limited to, aromatic ketones and tertiary amines. Suitable aromatic
ketones include, but are not limited to, benzophenone,
acetophenone, benzil, benzaldehyde, and o-chlorobenzaldehyde,
xanthone, thioxanthone, 9,10-anthraquinone, and many other aromatic
ketones. Suitable tertiary amines include, but are not limited to,
methyldiethanolamine, ethyldiethanolamine, triethanolamine,
phenylmethyl-ethanolamine, dimethylaminoethylbenzoate, and the
like. Typically, if used, an amount of photosensitizer is included
in the ceramer compositions to effect the desired level and rate of
cure. Preferably, the amount of photosensitizer used in the ceramer
compositions of the present invention is about 0.01 to about 10%,
more preferably about 0.05 to about 5%, and most preferably about
0.25 to about 3% by weight, based on the total weight of the
ceramer composition without solvent. It should be understood that
combinations of different photosensitizers can be used if
desired.
[0107] Polymeric materials are known to degrade by a variety of
mechanisms. Common additives that can offset this are known as
stabilizers, absorbers, antioxidants, and the like. The ceramer
compositions of the present invention can include one or more of
the following: ultraviolet stabilizer, ultraviolet absorber, ozone
stabilizer, and thermal stabilizer/antioxidant.
[0108] An ultraviolet stabilizer or ultraviolet absorber improves
weatherability and reduces the "yellowing" of the abrasion
resistant, ceramer coating with time. An example of an ultraviolet
stabilizer includes that available under the trade designation
"TINUVIN.TM. 292"
(bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate) and an example
of an ultraviolet absorber includes that available under the trade
designation "TINUVIN.TM. 1130" (hydroxyphenyl benzotriazole), both
of which are available from Ciba-Geigy. The ceramer composition can
include an amount of either an ultraviolet stabilizer or an
ultraviolet absorber to impart the desired result. Preferably, the
ultraviolet stabilizer or absorber is present in an amount up to
about 10% by weight, and more preferably about 1 to about 5%, based
on the total weight of the ceramer composition without solvent. It
should be understood that combinations of different ultraviolet
stabilizers and absorbers can be used if desired.
[0109] An ozone stabilizer protects against degradation resulting
from reaction with ozone. Examples of ozone stabilizers include,
but are not limited to, hindered amines such as that available
under the trade designation "IRGANOX.TM. 1010" available from
Ciba-Geigy and phenoltriazine commercially available from Aldrich.
The ceramer composition can include an amount of an ozone
stabilizer to impart the desired result. Preferably, the ozone
stabilizer is present in an amount up to about 1% by weight, more
preferably about 0.1 to about 1.0%, and most preferably about 0.3
to about 0.5%, based on the total weight of the ceramer composition
without solvent. It should be understood that combinations of
different ozone stabilizers can be used if desired.
[0110] A thermal stabilizer/antioxidant reduces the amount of
yellowing as a result of weathering. Examples of such materials
include, but are not limited to, low melting hindered phenols and
triesters. Specific examples include
2,6-di-tert-butyl-4-methylphenol commercially available under the
trade designation "ULTRANOX.TM. 226" antioxidant from Borg Warner
Chemicals, Inc., Parkersburg, N.Y.; octadecyl
3,5-di-tert-butyl-4-hydroxy- cinnamate commercially available under
the trade designations "ISONOX.TM. 132" antioxidant (Schenectady
Chemicals, Inc., Schenectady, N.Y.) or "VANOX.TM. 1320" antioxidant
(Vanderbilt Co., Inc., Norwalk, Conn.). The ceramer composition can
include sufficient thermal stabilizer/antioxidant to impart the
desired result. Preferably, the thermal stabilizer/antioxidant is
present in an amount up to about 3% by weight, and more preferably
about 0.5 to about 1%, based on the total weight of the ceramer
composition without solvent. It should be understood that
combinations of different thermal stabilizers/antioxidants can be
used if desired.
[0111] According to one approach, a ceramer composition of the
present invention is prepared by combining ingredients including a
fluoro/silane component, a crosslinkable silane component, a
curable binder precursor, and a colloidal inorganic oxide. The
fluoro/silane component may be combined with a first admixture
containing a colloidal inorganic oxide and a curable binder
precursor in the presence of a crosslinkable silane component. The
fluoro/silane component may be premixed with the crosslinkable
silane component to form a second admixture, which second admixture
is then combined with the first admixture to form a third
admixture, namely the ceramer composition. The crosslinkable silane
component may also be premixed with the first admixture to provide
a fourth admixture which can then be combined with the
fluoro/silane component to form the ceramer composition.
[0112] The fluoro/silane component, first admixture and
crosslinkable silane component are combined under conditions such
that at least a portion of the colloidal inorganic oxides is
surface treated by the fluoro/silane component. Preferably, once so
combined, the hydrolyzable silane moieties of the fluoro/silane
component and the crosslinkable silane component are allowed to
react with and thereby functionalize (surface treat) the colloidal
inorganic oxides with pendant R, and R.sub.f functionality. By
incorporating the fluoro/silane component into the ceramer
composition in this manner, the resultant ceramer composition
remains optically clear and, therefore, is especially useful for
forming optically clear ceramer coatings.
[0113] The ceramer composition is then stripped, e.g., heated under
vacuum to remove substantially all of the water. For example,
removing about 98% of the water, thus leaving about 2% water in the
ceramer composition, has been found to be suitable. When the
curable binder precursor contains free-radically-curable
prepolymers, the resultant dried ceramer composition is a clear
liquid. As soon as substantially all of the water is removed, an
organic solvent of the type described above is added, if desired,
in an amount such that the ceramer composition preferably includes
from about 5% to about 95% by weight solids, more preferably from
about 10% to about 50% by weight solids and most preferably from
about 15% to about 30% by weight solids.
[0114] The resultant ceramer composition is then coated onto any
substrate for which it is desired to improve one or more of
abrasion resistance, impact resistance or stain resistance.
Examples of such substrates include any and all thermosetting or
thermoplastic items such as camera lenses, eyeglass lenses,
binocular lenses, automobile windows and body panels as an
automotive topcoat, building windows, bakeware, train windows, boat
windows, aircraft windows, vehicle headlamps and taillights,
display cases, eyeglasses, watercraft hulls, overhead projectors,
stereo cabinet doors, stereo covers, furniture, bus station
plastic, television screens, computer screens, watch covers,
instrument gauge covers, optical and magneto-optical recording
disks, graphic displays, and the like. Adhesion of the ceramer
coating to the substrate may vary depending on the particular
substrate and on other factors such as whether the substrate is
primed, oriented during manufacture (unoriented or oriented axially
or biaxially) or otherwise modified.
[0115] The ceramer compositions of the present invention may also
be applied to animal skin products such as leather, and to
synthetic leather products to protect such products from stains,
abrasion, scuffing, cracking, and wear. Typically, the ceramer
composition is applied to these products using spray, brush, roll,
or transfer coating methods.
[0116] Any suitable coating technique can be used for applying the
ceramer composition to the substrate, depending upon the nature of
the substrate, the viscosity of the ceramer composition, and the
like. Examples of suitable coating techniques include spin coating,
gravure coating, flow coating, spray coating, coating with a brush
or roller, screen printing, knife coating, curtain coating, slide
curtain coating, extrusion, squeegee coating, and the like. Typical
protective ceramer coatings of the present invention have a
thickness in the range from about 1 micron to about 100 microns,
preferably about 2 to about 50 microns, more preferably about 4 to
about 9 microns. Generally, ceramer coatings that are too thin may
not have sufficient abrasion or impact resistance, and tend to run,
thereby causing a waste of material. Ceramer films that are too
thick may have a greater tendency to crack.
[0117] After coating, the solvent can be flashed off with heat or
allowed to evaporate under ambient conditions. If radiation
curable, the coated ceramer composition is then cured by
irradiation with a suitable form of energy, such as visible light,
ultraviolet light or electron beam radiation. Irradiating with
ultraviolet light in ambient conditions is presently preferred due
to the relative low cost and speed of this curing technique.
Irradiation causes the curable binder precursor and the surface
treated, colloidal inorganic oxides to crosslink together to form a
ceramer coating containing a polymer matrix having the colloidal
inorganic oxides, and any optional additives, interspersed in the
polymer matrix. The resultant ceramer-coated substrate is thereby
protected against stains, abrasion, and impact.
[0118] The present invention will now be further described with
reference to the following examples.
EXAMPLES
[0119] Test Methods
[0120] Test Procedure I: Taber Abrasion Test on Plastic
[0121] This test measures the Taber abrasion of the ceramer
composition when coated on a substrate and was performed according
to ASTM D1044 (Standard Method for Resistance of Transparent
Plastics to Surface Abrasion), the disclosure of which is
incorporated herein by reference. Briefly, the test method involved
abrading a sample on a TABER ABRASER.TM. tester for 100, 300 and
500 cycles using a 500 gram load with a CS-10F wheel at room
temperature. After each cycle of exposure to the abrasive wheels
the percent change in haze was measured.
[0122] Test Procedure II: Warm Water Adhesion Test
[0123] This test was designed to test the ceramer composition's
durability when coated on a substrate and submersed in water at
elevated temperatures. The sample was completely submerged in water
at the stated temperature for the stated time period. Specifically,
the samples were submerged in water baths at about 60.degree. C.
for 11 and 13 days, at about 71.degree. C. for 6 and 8 days and at
about 82.degree. C. for 3 and 5 days. At the end of the stated time
period, the samples were removed, examined for any delamination and
subjected to a Cross Hatch Adhesion Test (Test Procedure IV
described below) and to a Tape Snap Test (Test Procedure V
described below).
[0124] Test Procedure III: Weatherability
[0125] This test assesses the ability of the ceramer composition,
when coated on a substrate, to withstand weathering conditions
(e.g., sunlight). The test was conducted according to ASTM Test
Standard G-26-88, Type B, BH (Standard Practice for Operating Light
Exposure Apparatus (Xenon-Arc Type) with and without Water for
Exposure of Nonmetallic Materials), the disclosure of which is
incorporated by reference herein.
[0126] Briefly, a sample was exposed to a 6500 Joule/second xenon
burner filter through borosilicate inner and outer filters at
0.35W/m.sup.2 in a Water Cooled Xenon Arc Model 65XWWR Weathering
Chamber, available from Atlas Electric Devices Co. (Chicago, Ill.)
for repetitive cycles of 102 minutes at about 63.degree. C.
followed by 18 minutes with a water spray. To provide a ceramer
coating passing this test for a particular substrate, the ceramer
coating must be capable of withstanding at least 1000 hours of
exposure under these conditions with no significant yellowing,
whitening, or other discoloration.
[0127] Undesirable results obtained from this weathering test
include, in particular, whitening, delamination, and "checks",
which are imperfections in the form of slight inclusions in the
coating.
[0128] Test Procedure IV: Cross Hatch Adhesion Test
[0129] The test method assesses the adhesion of coating films to
substrates by applying and removing pressure-sensitive adhesive
tape over cuts made in a film of the coating composition. A
crosshatch pattern with 3 cuts in each direction was made in the
coating on the substrate. Then a pressure-sensitive adhesive tape
was applied over the crosshatch and removed. Adhesion was evaluated
by comparing descriptions and illustrations. The cutting tool was a
sharp razor blade, scalpel, knife or other cutting device which had
a cutting edge in good condition. A cutting guide was used to
ensure straight cuts. The tape was 1 inch (25 mm) wide
semi-transparent pressure-sensitive adhesive tape with an adhesion
strength of 36 plus or minus 2.5 oz/in. (40 plus or minus 2.8 g/mm)
when tested in accordance with ASTM Test Method B 1000 incorporated
by reference herein in its entirety.
[0130] An area free of blemishes and minor surface imperfections on
the coating was selected. Care was taken to ensure that the surface
was clean and dry. Extremes in temperature or relative humidity
which may affect the adhesion of the tape or the coating were
avoided. Two sets of three parallel 20 mm long cuts were made in
the coating, with one set oriented at 90.degree. to cuts in the
other set and the sets intersecting near the middle of the test
panel. The cuts were made in one steady motion to penetrate through
the coating to the substrate, leaving the substrate visible through
the coating. After cutting, the film was lightly brushed to remove
detached flakes or ribbons of coatings. A piece of tape 75 mm long
was removed from the roll and placed with the center of tape at the
intersection of the cuts with the tape running in the same
direction as one set of the cuts. The tape was smoothed in place
with finger in the area of the cuts and then rubbed firmly with an
eraser on the end of a pencil. Within 90 seconds (plus or minus 30
seconds) of application, the tape was removed by creasing a free
end and pulling it off rapidly at about 180.degree., without
jerking the tape back upon itself. The cut area was then inspected
for removal of coating from the substrate and rated for adhesion
according to the following scale:
[0131] A coating was designated "pass" if:
[0132] the edges of the cuts are completely smooth; none of the
squares of the lattice is detached; or
[0133] small flakes of the coating are detached at intersections;
(less than 5% of the area is affected); or
[0134] small flakes of the coating are detached along edges and at
intersections of cuts; (the area affected is 5 to 15% of the
lattice).
[0135] The coating was designated "fail" if:
[0136] the coating has flaked along the edges and on parts of the
squares; (the area affected is 15 to 35% of the lattice); or
[0137] the coating has flaked along the edges of cuts in large
ribbons and whole squares have detached; (the area affected is 35
to 65% of the lattice).
[0138] Test Procedure V: Tape Snap Test
[0139] A section of adhesive tape was affixed to the surface of the
coating with the end of the tape overlapping the edge of the sheet.
The tape was then "snapped" off by pulling it rapidly at 90.degree.
to the surface of the coating, and the coating visually inspected
for evidence of delamination. A coating was designated "pass" if
minor or no evidence of delamination was found.
[0140] Test Procedure VI: Taber Abrasion Test on Leather
[0141] This test measures the Taber abrasion of the ceramer
composition when coated on a leather substrate and was performed
according to ASTM D3884, the disclosure of which is incorporated
herein by reference. This test method measures the abrasion
resistance of the surface coating on leather and synthetic leathers
using a rotary rubbing action under controlled pressure. The Taber
abrasion machine used was Model number 5130 available from Taber
Industries, Tonawanda, N.Y. The samples were cut to about 103.+-.3
millimeters with a 7.+-.1 millimeter hole punched in the center of
the test sample. The samples were attached to the Taber disc with
S-36 cardboard backer (available from Taber Industries). The
testing was conducted using conditioned H-22 abrasive wheels with
1000 gram weights. A sample failed when a wear area of about 2
millimeters depth was observed.
Example 1
[0142] 56.2 Parts by weight of the curable binder precursor PETA
(pentaerythritol triacrylate) was heated to about 49.degree. C. in
a one liter flask. 35.2 Parts by weight silica (88 parts of 40%
solids, 20 nanometers average particle size, commercially available
from Nalco Corp., Naperville, Ill., under the trade designation
"Nalco 2327") were added to the PETA to form a first admixture. In
a separate flask, 7.7 parts by weight of the crosslinkable silane
component 3-methacryloxypropyl-trimethoxysilane, (commercially
available from Union Carbide under the trade designation "A-174")
were mixed with 0.8 parts by weight of fluoro/silane component of
Formula (11) (commercially available from Minnesota Mining and
Manufacturing Company, St. Paul, Minn. under the trade designation
"FC-405") to form a second admixture. The first and second
admixtures were then mixed together to form a third admixture. In a
weighing tray, 0.15 parts by weight BHT (butylated hydroxytoluene)
and 0.02 parts by weight phenothiazine (both based on the 56.2
parts by weight PETA) were mixed together and then added to the
third admixture to form a fourth admixture.
[0143] The fourth admixture was then "stripped" by subjecting it to
a gentle vacuum distillation (100.+-.20 mm Hg) at 52.+-.2.degree.
C. until most of the water/methanol was removed. A residual amount
(a few weight-percent) of water remained in the dried product. At
the end of the stripping process, the admixture was diluted to 50%
solids with a 14:1 weight-ratio solvent of isopropyl
alcohol:distilled water. This 50% solids admixture was further
diluted to 25% solids with the same solvent mixture. About 0.7
parts by weight photoinitiator (commercially available from Ciba
Geigy Corp., Hawthorne, N.Y., under the trade designation "IRGACURE
184") was also added.
[0144] The ceramer composition was then coated onto PMMA
(polymethylmethacrylate) and polycarbonate substrates at a
thickness of about 4 to about 5 micrometers using conventional flow
coating techniques. Each coated substrate was then flash dried at
about 60.degree. C. for 2.5 minutes in an air circulating oven to
ensure that the majority of the isopropanol was driven off.
Finally, the coating was cured on a conveyor belt of a UV light
processor using a high pressure mercury lamp (Model QC 1202,
available from PPG Industries, Plainfield, Ill.). The process
conditions were 16.5 meters/minute, 410 volts, energy 90
mJ/cm.sup.2, and an air atmosphere.
[0145] The resulting ceramer coatings were perfectly clear and
adhered to the PMMA and polycarbonate substrates. Furthermore, the
coatings passed Test Procedures I, II and III and had excellent
shelf stability. After 6 months, sols prepared in accordance with
the above procedure were clear, with no apparent flocculation.
Example 2
[0146] Example 2 was carried out as in Example 1 except that the
crosslinkable silane component was added to the first admixture of
PETA and silica, followed by addition of the fluoro/silane
component. These steps were performed by heating 56.2 parts by
weight of PETA to about 49.degree. C. in a one liter flask. 35.2
Parts by weight silica (88 parts by weight of 40% solids NALCO.TM.
2327) was added to the flask. 7.7 Parts by weight of
3-methacryloxypropyl-trimethoxysilane were then added to the flask,
followed by addition of 0.8 parts by weight of a fluoro/silane
component of Formula (11). In a weighing tray, 0. 15 part by weight
BHT and 0.02 parts by weight phenothiazine (both based on the 56.2
parts by weight PETA) were mixed together and then added to the
flask. The resulting admixture was then stripped, diluted with
solvent, coated onto PMMA and polycarbonate substrates and cured as
in Example 1. The resulting ceramer coatings were perfectly clear
and adhered to the PMMA and polycarbonate substrates. Furthermore,
the resulting ceramer coatings passed Test Procedures I, II and
III.
Example 3
[0147] Example 3 was carried out as in Example 1 except that the
fluoro/silane component was first added individually to the first
admixture of PETA and silica, followed by addition of the
crosslinkable silane component. These steps were performed by
heating 56.2 parts by weight of PETA to about 49.degree. C. in a
one liter flask. 35.2 Parts by weight silica (88 parts by weight of
40% solids NALCO 2327) were added to the flask. 0.8 Parts by weight
of the fluoro/silane component were then added to the flask,
followed by addition of 7.7 parts by weight of
3-methacryloxypropyl-trimethoxysilane. In a weighing tray, 0.15
parts by weight BHT and 0.02 parts by weight phenothiazine (both
based on the 56.2 parts by weight PETA) were mixed together and
then added to the flask. The final mixture precipitated. Thus, the
composition was not coatable and the experiment was not
completed.
Example 4
[0148] Example 4 was carried out as in Example 1 except that 15.6
parts by weight (based on 56.2 parts by weight PETA) of
dimethylacrylamide (DMA) was added to the third admixture of
Example 1 before addition of the mixture of BHT and phenothiazine.
The resulting admixture was then stripped, diluted with solvent,
coated onto PMMA and polycarbonate substrates and cured as in
Example 1. The resulting ceramer coatings were perfectly clear and
adhered to the PMMA and polycarbonate substrates. Furthermore, the
resulting ceramer coatings passed Test Procedures I, II and III and
performed as well as the coatings of Example 1. This example thus
shows that DMA may be used in the ceramer compositions of the
present invention, if desired, but is not required.
Example 5
[0149] Example 5 was prepared as described in Example 1, except a
silica/alumina mixture was substituted for the silica. Thus, 56.2
parts by weight of PETA were preheated to about 49.degree. C. and
then combined with 35.3 parts by weight of silica (88 parts by
weight of 40% solids NALCO.TM. 2327, 20nm) and 1 part by weight
sodium aluminate (NaAlO.sub.2) to form a first admixture. A second
admixture of 7.8 parts by weight of A-174 and 0.8 parts by weight
of the compound of Formula (11) was prepared and added to the first
admixture with stirring to form a third admixture. In a weighing
tray, 0.15 parts by weight BHT and 0.02 parts by weight
phenothiazine (both based on the 56.2 parts by weight PETA) were
mixed together and then added to the third admixture to form a
fourth admixture.
[0150] The fourth admixture was then stripped, diluted with
solvent, coated onto PMMA and polycarbonate substrates and cured as
in Example 1.
Example 6
[0151] Example 6 was carried out as described in Example 5, except
dimethylacrylamide was added to the other ingredients in the second
admixture. The second admixture contained about 0.7 parts by weight
of A-174, 0.8 parts by weight of the compound of Formula (11) and
8.0 parts by weight of dimethylacrylamide. The ceramer composition
was stripped, diluted with solvent, coated onto PMMA and
polycarbonate substrates and cured as in Example 1.
Comparative Example A
[0152] This ceramer composition contained dimethylacrylamide (DMA)
as a component of the binder precursor, but no fluoro/silane
component. Specifically, 51.5 parts by weight of PETA were heated
to about 49.degree. C. 32.4 Parts by weight silica (88 parts by
weight of 40% solids NALCO 2327) were added to the PETA to form a
first admixture. In a separate flask, 8.1 parts by weight of
3-methacryloxypropyl-trimethoxysil- ane were mixed with 8.0 parts
by weight DMA to form a DMA-altered second admixture. The first
admixture was mixed with the DMA-altered second admixture to form a
third admixture. In a weighing tray, 0.15 parts by weight BHT and
0.02 parts by weight phenothiazine (both based on the 51.5 parts by
weight PETA) were mixed together and then added to the third
admixture to form a fourth admixture.
[0153] The fourth admixture was then stripped, diluted with
solvent, coated onto PMMA and polycarbonate substrates and cured as
in Example 1. Like the ceramer coating of Example 1, the ceramer
coatings of this comparative example were perfectly clear, adhered
to the PMMA and polycarbonate substrates, and passed Test
Procedures I, II and III. Thus in these tested respects, a
composition of the invention performed comparably to a ceramer made
using DMA but no fluoro/silane component.
Comparative Example B
[0154] Comparative Example B was prepared as described in Example 2
except that no fluoro/silane component was added. 56.2 Parts by
weight of PETA were heated to about 49.degree. C. (120.degree. F.)
in a one liter flask. 35.2 Parts by weight silica (88 parts by
weight of 40% solids NALCO 2327) were added to the PETA to form a
first admixture. 7.7 Parts by weight of
3-methacryloxypropyl-trimethoxysilane were then added to the flask,
followed by the addition of 15.6 parts by weight DMA (based on 56.2
parts by weight PETA). In a weighing tray, 0.15 parts by weight BHT
and 0.02 parts by weight phenothiazine (both based on the 56.2
parts by weight PETA) were mixed together and then added to the
flask.
[0155] The resulting admixture was then stripped, diluted with
solvent, coated onto PMMA and polycarbonate substrates and cured as
in Example 2. Like the ceramer coating of Example 2, the ceramer
coatings of this comparative example were perfectly clear, adhered
to the PMMA and polycarbonate substrates, and passed Test
Procedures I, II and III. Thus in these tested respects, a
composition of the invention performed comparably to a ceramer made
using DMA but no fluoro/silane component.
Comparative Example C
[0156] Comparative Example C was a hardcoating prepared using
commercially available coating material from Cyro Corp., Rockaway,
N.J., under the trade designation "CYRO AR".
Comparative Example D
[0157] A mixture was prepared as described in Comparative Examples
A and B, omitting DMA. The resulting mixture coagulated on
stripping.
Summary of Results
[0158] The ceramer coatings described above were evaluated using a
variety of test methods. As is illustrated in the following Tables
3 through 10 and in Examples 1-2 and 4, a nonionic fluorochemical
containing both a fluorinated moiety and a silane moiety (the
fluoro/silane component) can be successfully incorporated into a
ceramer sol, without causing colloid flocculation. Ceramer coatings
containing such a fluoro/silane component, whether prepared with or
without DMA, have surprisingly long shelf lives and excellent stain
resistant characteristics (See Examples 1 and 4). Additionally,
ceramer compositions of the present invention can be used to
prepare ceramer coatings that exhibit a high level of abrasion
resistance, durability and hardness (See Tables 3-10). Some of the
coatings shown in Tables 3-10 employed additives whose formulations
are set out in Table 1 and whose ingredients are further identified
in Table 2. The amounts of such additives are expressed based on
the weight of ceramer solids.
1TABLE 1 Additive Components I 0.9 parts by weight "TINUVIN.sup.1
123" 1.6 parts by weight "SANDUVOR.sup.2 3058" 2.8 parts by weight
"TINUVIN 1130" 2.8 parts by weight "TINUVIN 400" II "TINUVIN 292"
III 2 parts by weight "TINUVIN 292" 2 parts by weight "TINUVIN 384"
IV 1.2 parts by weight "TINUVIN 123" 0.7 parts by weight "SANDUVOR
3058" 2.07 parts by weight "TINUVIN 384" 2.07 parts by weight
"TINUVIN 400" .sup.1TINUVIN, all grades, is commercially available
from Ciba-Geigy Corporation, Hawthorne, NY .sup.2SANDUVOR, all
grades, is commercially available from Clariant Corp, Charlotte,
NC
[0159]
2TABLE 2 Trade Name Chemical Name TINUVIN 123
bis-(1-octyloxy-2,2,6,6, tetramethyl-4- piperidinyl) sebacate
SANDUVOR 3058 N-acrylated HALs compound TINUVIN 400
1,3-benzenediol, 4-[4,6-bis(2,4-dimethyl)-1,3,5- triazin-2-yl] CG
TINUVIN 292 bis-(1,2,2,6,6-pentamethyl-4-piperidi- nyl) sebacate CG
TINUVIN 1130 hydroxyphenyl benzotriazole TINUVIN 384
3-(2H-benzotriazol-2-YL)-5-(tert-butyl)-4- hydroxybenzenepropanoic
acid
[0160]
3TABLE 3 Taber Abrasion Test - Coated on PMMA % HAZE Sample 100
cycles 300 cycles 500 cycles Comp. A* 2.6 3.1 4.1 Example 4* 2.0
3.0 3.6 Comp. B 1.4 3.0 3.9 Example 1 1.3 3.1 3.9 Example 4 0.9 2.4
3.2 Comp. A** 1.9 3.6 4.2 Comp. B** 1.5 2.8 3.7 Example 1** 1.6 3.3
4.1 Example 4** 1.3 2.9 3.5 Samples denoted with "*" included 4
wt-% of additive III on ceramer weight basis. Samples denoted with
"**" included 2 wt-% of additive II.
[0161]
4TABLE 4 Taber Abrasion Test - Coated on Polycarbonate % HAZE
Sample 100 cycles 300 cycles 500 cycles Example 1 1.7 3.3 4.1
Example 4 1.3 2.8 3.5 Comp. A* 3.1 3.2 3.8 Example 4* 2.8 2.7 3.1
Comp. B 1.3 2.3 3.2 Example 1 1.0 2.5 3.2 Example 4 1.0 2.3 3.1
Comp. A** 2.5 2.9 4.4 Comp. B** 3.0 2.5 3.5 Example 1** 3.0 2.6 3.3
Example 4** 2.7 2.2 3.1 Comp. C. 2.5 3.0 3.8 Samples denoted with
"*" included 6 wt-% of additive IV on a ceramer weight basis.
Samples denoted with "**" included 8 wt-% of additive I.
[0162]
5TABLE 5 Warm Water Adhesion Test - Coated on PMMA Sample 11 days @
60.degree. C. 8 days @ 71.degree. C. 3 days @ 82.degree. C. Example
1 pass Pass pass Example 4 pass Pass pass Comp. A* pass Pass pass
Example 4* pass Pass pass Samples denoted with "*" included 4 wt-%
of additive III on a ceramer weight basis.
[0163]
6TABLE 6 Warm Water Adhesion Test - Coated on PMMA Sample 13 days @
60.degree. C. 6 days @ 71.degree. C. 5 days @ 82.degree. C. Comp. B
pass pass pass Example 1 pass pass pass Example 4 pass pass pass
Comp. A* pass pass pass Comp. B* pass pass pass Example 1* pass
pass pass Example 4* pass pass pass Comp. C. pass pass pass Samples
denoted with "*" included 2 wt-% of additive II on a ceramer weight
basis.
[0164]
7TABLE 7 Warm Water Adhesion Test - Coated on Polycarbonate Sample
11 days @ 60.degree. C. 8 days @ 71.degree. C. 3 days @ 82.degree.
C. Comp. A pass pass pass Example 1 pass pass pass Example 4 pass
pass pass Comp. A* pass pass pass Example 4* pass pass pass Samples
denoted with "*" included 6 wt-% of additive IV on a ceramer weight
basis.
[0165]
8TABLE 8 Warm Water Adhesion Test - Coated on Polycarbonate Sample
13 days @ 60.degree. C. 6 days @ 71.degree. C. 5 days @ 82.degree.
C. Comp. A pass pass pass Comp. B pass pass pass Example 1 pass
pass pass Example 4 pass pass pass Comp. A* pass pass delaminated
Comp. B* pass pass delaminated Example 1* pass pass delaminated
Example 4* pass pass delaminated Comp. C. pass pass pass Samples
denoted with "*" included 8 wt-% of additive I on a ceramer weight
basis.
[0166]
9TABLE 9 Weathering Test - Coated on PMMA Sample Hours Example 1
1400 - few small checks Example 4 1400 - few small checks Comp. A
1400+ Example 1* 3700 - few long checks Example 4* not done Comp.
A* 3515+ Example 1 1800 - checks, slight whitening Example 4 1800 -
checks, slight whitening Comp. B 1800 - checks, slight whitening
Example 1** 2425+ Example 4** 2525+ Comp. A** 3515+ Comp. B** 2425+
+denotes that the test is on going Samples denoted with "*"
included 4 wt-% of additive III. Samples denoted with "**" included
2 wt-% of additive II.
[0167]
10TABLE 10 Weathering Test - Coated on Polycarbonate Sample Hours
Example 1 1000 - 20% delamination Example 4 1000 - total
delamination Comp. A .about.800 Example 1* 2400 - slight
delamination Example 4* not done Comp. A* 2200 Example 1 .about.750
Example 4 .about.750 Comp. A .about.800 Comp. B .about.900 Example
1** 2425 - slight delamination & very small checks Example 4**
2425 - slight delamination & very small checks Comp. A**
.about.2500 Comp. B** 2425 - slight delamination Samples denoted
with "*" included 6 wt-% of additive IV. Samples denoted with "**"
included 8 wt-% of additive I.
[0168] In the following Examples, coating formulations were
prepared as in Example 1 using various inorganic oxides. The
coating compositions were coated onto either acrylic (Cyro-FF.TM.,
available from Cyro Inc.) or polycarbonate (Cyro-ZX.TM., available
from Cyro Inc.) substrates and cured as previously described. The
cured coatings were then subjected to the Taber Abrasion Test on
Plastic. As a comparative test, acrylic and polycarbonate sheets
coated with a proprietary abrasion-resistant coating (Cyro-AR.TM.,
available from Cyro Inc.) were also tested. The inorganic oxides
used and the results of the abrasion tests are shown in Tables 11
and 12.
11TABLE 11 % HAZE on Acrylic Inorganic Sample Oxide 100 cycles 300
cycles 500 cycles Comp. E Cyro-AR 2.2 4.3 5.7 Example 7
SiO.sub.2/NaAlO.sub.2 1.3 3.2 4.2 99:1 Example 8
SiO.sub.2/NaAlO.sub.2 1.0 2.5 3.4 98:2 Example 9
SiO.sub.2/ZrO.sub.2 2.3 4.6 7.6 95:5 Example 10 SiO.sub.2/ZrO.sub.2
3.2 6.5 9.5 90:10 Example 11 SiO.sub.2/SnO.sub.2 1.2 3.2 4.2
95:5
[0169]
12TABLE 12 % HAZE on Polycarbonate Inorganic Sample Oxide 100
cycles 300 cycles 500 cycles Comp. F Cyro-AR 2.2 2.9 3.5 Example 12
SiO.sub.2/NaAlO.sub.2 1.0 2.4 3.4 99:1 Example 13
SiO.sub.2/NaAlO.sub.2 0.6 1.7 2.5 98:2 Example 14
SiO.sub.2/ZrO.sub.2 1.8 3.6 5.2 95:5 Example 15 SiO.sub.2/ZrO.sub.2
2.1 4.8 7.1 90:10 Example 16 SiO.sub.2/SnO.sub.2 0.7 2.0 3.0
95:5
[0170] As can be seen from the data, all the samples provide good
abrasion resistance on both acrylic and polycarbonate substrates.
In particular, the coatings containing NaAlO.sub.2 or mixed oxides
of SiO.sub.2 and SnO.sub.2 provide improved abrasion resistance
relative to commercially available coatings.
Examples 17 to 26
[0171] In the following Examples, coating formulations were
prepared as in Example 1 using various inorganic oxides. The
coating compositions were coated onto either acrylic
(Cyro-ACRYLITE.TM., available from Cyro Inc.) or polycarbonate
substrates (Cyro-CYROLON.TM., available from Cyro Inc.) and cured
as previously described. The cured coatings were then subjected to
the Warm Water Adhesion Test. The results are set out below in
Tables 13 and 14.
13TABLE 13 Warm Water Adhesion Test on Acrylic 10 days 5 days 5
days Cross Sample Inorganic oxide @ 57.degree. C. @ 68.degree. C. @
78.degree. C. Hatch test Exam- SiO.sub.2/NaAlO.sub.2 pass pass pass
pass ple 17 99:1 Exam- SiO.sub.2/NaAlO.sub.2 pass pass pass pass
ple 18 98:2 Exam- SiO.sub.2/ZrO.sub.2 pass pass pass pass ple 19
95:5 Exam- SiO.sub.2/ZrO.sub.2 pass pass pass pass ple 20 90:10
Exam- SiO.sub.2/SnO.sub.2 pass pass pass pass ple 21 95:5
[0172]
14TABLE 14 Warm Water Adhesion Test on Polycarbonate 10 days 5 days
5 days Cross Sample Inorganic oxide @ 57.degree. C. @ 68.degree. C.
@ 78.degree. C. Hatch test Exam- SiO.sub.2/NaAlO.sub.2 pass pass
pass pass ple 22 99:1 Exam- SiO.sub.2/NaAlO.sub.2 pass pass pass
pass ple 23 98:2 Exam- SiO.sub.2/ZrO.sub.2 pass pass pass pass ple
24 95:5 Exam- SiO.sub.2/ZrO.sub.2 pass pass pass pass ple 25 90:10
Exam- SiO.sub.2/SnO.sub.2 pass pass pass pass ple 26 95:5
Examples 27 to 30
[0173] In the following Examples the effect of the fluorochemical
on graffiti resistance was evaluated. Several compositions were
coated onto either acrylic or polycarbonate substrates and cured as
previously described. In the first of two tests the coated
substrate was written upon with a SHARPIE.TM. marker and the ink
was allowed to dry. Then removal of the ink was attempted by
rubbing with a paper tissue. If all of the ink was removed, the
coating was acceptable and rated as "pass".
[0174] In the second test, Rust-Oleum.TM. spray paint was applied
to the coated substrate. The spray can was held about 20 to 25 from
the sample and a one-second burst was applied to form a spot of
paint. Next the spray can was held the same distance from the
sample and a line of paint was applied with a three-second burst.
Then the paint was allowed to dry and removal of the paint was
attempted by rubbing with a paper tissue. If all of the paint was
removed, the coating was rated as a "pass". The coating composition
of Comparative Example A was similarly evaluated.
[0175] The results of the tests are shown below in Table 15.
15TABLE 15 Coating Sample Composition Substrate Ink Paint Example
27 Example 1 Polycarbonate pass pass Example 28 Example 4
Polycarbonate pass pass Comp. E Comp. A Polycarbonate fail fail
Example 29 Example 1 Acrylic pass pass Example 30 Example 4 Acrylic
pass pass Comp. F Comp. A Acrylic fail fail
[0176] The above results show that coating compositions of the
present invention benefit from the incorporation of a
fluorochemical and are useful as anti-graffiti coatings. In
contrast, coating lacking the fluorochemical remained soiled by ink
and paint.
Example 31
[0177] Two white full grain leathers (available from Sadesa, Buenos
Aires, Argentina) designated #2040 and #2059 were spray coated with
the ceramer composition of Example 1, using a commercial sprayer
and holding the leather 2 sample in a horizontal position. The
coating weight was 11 grams/meters.sup.2. The samples were then
oven dried for about 10 minutes at 70.degree. C. The samples were
then cured using a UV chamber with mercury vapor lamps (power
setting--300 Joules/seconds/meters.sup.2 ) at a speed of 6
meters/minute.
[0178] The samples were tested according to the Taber Abrasion Test
on Leather. The results are set out below in Table 16.
16TABLE 16 Sample Uncoated Coated with Ceramer #2040 75 cycles 225
cycles #2059 125 cycles 600 cycles
[0179] Other embodiments of this invention will be apparent to
those skilled in the art upon consideration of this specification
or from practice of the invention disclosed herein. Various
omissions, modifications, and changes to the principles and
embodiments described herein may be made by one skilled in the art
without departing from the true scope and spirit of the invention
which is indicated by the following claims.
* * * * *