Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR OBTAINING COATING
COMPOSITIONS HAVING REDUCED VOC
[0001] This application is a continuation-in-part of and claims priority on
10/351,079, filed January 23, 2003, which is a divisional of U.S. 6,541,594,
filed
December 19, 2000.
FIELD OF THE INVENTION
[0002] The invention relates to the manufacture of thermosetting polymers
and/or oligomers for use in curable coating compositions, especially curable
coating
compositions having a low or reduced VOC.
BACKGROUND OF THE INVENTION
[0003] Curable thermoset coating compositions are widely used in the
coatings art. They are often used as topcoats in the automotive and industrial
coatings
industry. ,Such topcoats may be basecoats, clearcoats, or mixtures thereof.
Color-
plus-clear composite coatings are particularly useful as topcoats where
exceptional
gloss, depth of color, distinctness of image, or special metallic effect is
desired. The
automotive iildustry has made extensive use of these coatings for automotive
body
panels.
[0004] Color-plus-clear composite coatings, however, require an extremely
high degree of clarity in the clearcoat to achieve the desired visual effect.
High-gloss
coatings also require a low degree of visual aberrations at the surface of the
coating in
order to achieve the desired visual effect such as high distinctness of image
(DOI).
Finally, such composite coatings must also simultaneously provide a desirable
balance
of finished film properties such as durability, hardness, flexibility, and
resistance to
environmental etch, scratching, marring, solvents, andlor acids.
[0005] In order to obtain the extremely smooth finishes that are generally
required in the coatings industry, coating compositions must exhibit good flow
before
curing. Good flow is observed when the coating composition is fluid enough at
some
point after it is applied to the substrate and before it cures to a hard film
to take on a
smooth appearance. Some coating compositions exhibit good flow immediately
upon
application and others exhibit good flow only after the application of
elevated
temperatures.
[0006] One way to impart fluid characteristics and good flow to a coating
composition is to incorporate volatile organic solvents into the composition.
These
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solvents provide the desired fluidity and flow during the coating process, but
evaporate upon exposure to elevated curing temperatures, leaving only the
coating
components behind.
[0007] However, the use of such solvents increases the volatile organic
content (VOC) of the coating composition. Because of the adverse impact that
volatile organic solvents may have on the environment, many government
regulations
impose limitations on the amount of volatile solvent that can be used.
Increasing the
percentage nonvolatile (%NV) of a coating composition or decreasing the VOC
provides a competitive advantage with respect to environmental concerns, air
permitting requirements and cost.
[0008] Prior art attempts to improve the VOC of polymers and coating
compositions have generally focused on the removal of volatile organic
solvents from
polymers by methods such as vacuum distillation. However, such techniques have
significant disadvantages. First, they generally require the use of more
energy and
labor that leads to higher costs. Increased costs also result from the
disposal of
removed solvent. Finally, the viscosity of the stripped polymer often creates
processing and manufacturing challenges.
[0009] There is thus a continuing desire to reduce the volatile organic
content
(VOC) of coating compositions and the components of such coating compositions
while avoiding the problems of the prior art. This must be done without
sacrificing
the Theological properties of the coating composition required for trouble-
free
application of the composition while still maintaining the optimum level of
smoothness and appearance. Finally, any such coating composition must continue
to
provide finished filins having a good combination of properties with respect
to
durability, hardness, flexibility, and resistance to chipping, environmental
etch,
scratching, marring, solvents, and/or acids.
[0010] More particularly, it would be very desirable to provide a method of
making film-forming components for coating compositions wherein the film-
forming
component is polymerized in a material that is inert with respect to
polymerization but
does not volatilize upon exposure to elevated curing temperature. Ideally,
such a
material would enter into the film-forming reaction of a thermosetting coating
composition. The desired effect of incorporating the material into the final
filin would
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be to increase the crosslink density of the cured film and to impart positive
film
attributes such as etch resistance, flexibility, scratch and mar, or chip
resistance.
[0011] Accordingly, it would be advantageous to provide economical methods
of making binders for curable coating compositions which provide all of the
advantages of prior art binders, but that contribute lower levels of volatile
organic
solvents to the final coating composition while still providing desirable
application
properties as well as finished films having commercially acceptable appearance
and
performance properties.
[0012] It would also be advantageous to provide a method of making acrylic
oligomers and/or polymers for curable coating compositions which provide all
of the
advantages of prior art acrylic oligomers and binders, but that contribute
lower levels
of volatile organic solvents to the final coating composition while still
providing
desirable application properties as well as finished films having commercially
acceptable appearance and performance properties.
[0013] Finally, it would be especially desirable to provide a method of making
film-forming components for curable coating compositions wherein the film-
forming
component is polymerized in a material that fiznctions as a solvent with
respect to the
film forming component and that (1) is inert with respect to polymerization,
(2) does
not contribute to the VOC of a coating composition incorporating said film-
forming
component, and (3) enters into the film-forming reaction when the coating
composition is cured.
SUMMARY OF THE INVENTION
[0014] In one exemplary embodiment, the disclosed method comprises
providing a mixture (I) comprising a reactant mixture (a) and a nonvolatile
solvent
(b"~), wherein reactant mixture (a) comprises one or more polymerizable
components
and nonvolatile solvent (b"~) (i) is not a crystalline solid at 25°C,
(ii) is nonvolatile,
(iii) comprises at least one functional group (Fl) and (iv) is a fluid solid.
The reactant
mixture (a) is subjected to polymerization conditions sufficient to polymerize
reactant
mixture (a) to provide a polymer (a'). The nonvolatile solvent (b"~) is
subjected to
reaction conditions wherein the at least one functional group (F1) of
nonvolatile
solvent (b"~) is reacted with at least one reactant (e) to provide a
nonvolatile solvent
(b'"~) comprising at least two functional groups (FZ). The disclosed method
results in a
mixture (II) of a polymer (a') in a nonvolatile solvent (b'"~) comprising at
least two
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functional groups (F2). The at least one functional group (F1) is
substantially
nonreactive: (1) with the components of reactive mixture (a), (2) under the
polymerization conditions in which reactant mixture (a) is polymerized, and
(3) with
polymer (a').
[0015] Also disclosed is a reactive polymer composition, comprising an acrylic
polymer or resin (a') comprising a functional group (F3) that is at least one
of a
primary carbamate group, a primary hydroxyl group, a secondary hydroxyl group,
and
mixtures thereof, and a nonvolatile solvent (b'"~) that is not a crystalline
solid at 75°C
but is a fluid solid at the temperature at which polymer (a') was polymerized,
the
nonvolatile solvent (b') comprising (i) four or more isomers, and (ii) at
least two
reactive functional groups (F2~ that are selected from primary carbamate,
primary
hydroxyl, and secondary hydroxyl, wherein no more than 10% of the sum of
functional groups (F2) and (F3) are primacy hydroxyl groups and at least 60%
of the
sum of functional groups (F2) and (F3) are primary carbamate groups.
In one exemplary embodiment, the reactive polymer composition is made by a
disclosed method.
[0016] In another exemplary embodiment, a method of making an acrylic
polymer is provided. The disclosed method comprises providing a mixture (I)
comprising a reactant mixture (a) and a solvent mixture (b) comprising a
nonvolatile
solvent (b"~), wherein reactant mixture (a) comprises one or more
ethylenically
unsaturated monomers and nonvolatile solvent (b"~) (i) is not a crystalline
solid at
25°C, (ii) is nonvolatile, and (iii) comprises at least one functional
group (Fl),
polymerizing the reactant mixture (a) under free radical polymerization
conditions in
the solvent mixture (b) to provide an acrylic polymer (a'), and subjecting the
nonvolatile solvent (b"~) to reaction conditions wherein the at least one
functional
group (Fl) of nonvolatile solvent (b"~) is reacted with at least one reactant
(e) to result
in at least two functional groups (Fa), said method producing a mixture (II)
comprising
the acrylic polymer (a') in nonvolatile solvent (b'"~), wherein the at least
one
functional group (Fl) is substantially nonreactive: (1) with the components of
reactive
mixture (a), (2) under the polymerization conditions in which reactant mixture
(a) is
polymerized, and (3) with polymer (a').
[0017] Also disclosed are curable coating compositions comprising a mixture
(II) comprising a polymer (a') and a nonvolatile solvent (b'"~) comprising at
least two
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functional groups (F2), the mixture (II) made by the process comprising
providing a
mixture (I) comprising a reactant mixture (a) and a nonvolatile solvent (b"~),
wherein
reactant mixture (a) comprises one or more polymerizable components and the
nonvolatile solvent (b"~) (i) is not a crystalline solid at 25°C, (ii)
is nonvolatile, (iii)
comprises at least one functional group (Fl), and (iv) is a fluid solid,
polymerizing the
reactant mixture (a) to provide a polymer (a'), and subjecting nonvolatile
solvent (b"~)
to reaction conditions wherein the at least one functional group (F1) of
nonvolatile
solvent (b"~) is reacted with at least one reactant (e) to obtain at least two
functional
groups (F2), with the provisos that the functional groups (Fl) and (F2) are
not the same
and the at least one functional group (Fl) is substantially nonreactive: (1)
with the
components of reactive mixture (a), (2) under the polymerization conditions in
which
reactant mixture (a) is polymerized, and (3) with polymer (a'), and at least
one
crosslinking agent (f) comprising at least one functional group (fi) which is
reactive
with functional groups (F2) of nonvolatile solvent (b'"~).
[0018] Coating compositions of the invention comprising crosslinking agent
(f) and a mixture (II) comprising polymer (a') and nonvolatile solvent (b'"~)
comprising at least two functional groups (F2) provide coating compositions
having
low or reduced VOCs without any reduction in application or performance
properties.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The invention provides a method of making a polymer (a'), especially
a mixture (II) comprising a polymer (a') and at least one nonvolatile solvent
(b'"V)
comprising at least two functional groups (F2). The mixture (II) of polymer
(a') and at
least one nonvolatile solvent (b'"~) comprising at least two functional groups
(F2) is
especially suitable for use in coating compositions having low VOCs. In
another
exemplary embodiment, mixture (II) will comprise a polymer (a') and a solvent
mixture (b), wherein solvent mixture (b) comprises at least one nonvolatile
solvent
(b'"~) comprising at least two functional groups (FZ).
[0020] The invention also provides a reactive polymer composition, comprising
an acrylic resin (a') comprising a functional group (F3) that is at least one
of a primary
carbamate group, a primary hydroxyl group, a secondary hydroxyl group, and
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mixtures thereof, and a nonvolatile solvent (b'"~) that is a noncrystalline
solid at 75°C
and comprises (i) four or more isomers, and (ii) at least two reactive
functional groups
(F2) that are selected from primary carbamate, primary hydroxyl, and secondary
hydroxyl, wherein no more than 5% of the sum of functional groups (F2) and
(F3) are
primary hydroxyl groups and at least 60% of the sum of functional groups (Fz)
and
(F3) are primary carbamate groups. The reactive polymer composition may be
made
by the method set forth above.
[0021] A 'low VOC polymer or coating composition' as used herein refers to
polymers or coating compositions having a volatile organic content (VOC) of no
more
than about 3.2 lbs. of volatile organic solvent per gallon of polymer or
coating
composition, in some exemplary embodiments, no more than about 2.4 lbs. of
volatile
organic solvent per gallon of polymer or coating composition, and in some
especially
exemplary embodiments, no more than about 1.6 lbs. of volatile organic
solvents per
gallon of polymer or coating composition. The invention provides a reactive
polymer
composition, comprising an acrylic resin (a') comprising a functional group
(F3) that is
at least one of a primary carbamate group, a primary hydroxyl group, a
secondary
hydroxyl group, and mixtures thereof, and a nonvolatile solvent (b'"~) that is
a
noncrystalline solid at 75°C and comprises (i) four or more isomers,
and (ii) at least
two reactive functional groups (F2) that are selected from primary carbamate,
primary
hydroxyl, and secondary hydroxyl, wherein no more than 5% of the sum of
functional
groups (F2) and (F3) are primary hydroxyl groups and at least 60% of the sum
of
functional groups (F2) and (F3) are primary carbamate groups.
[0022] Mixture (II) results from a multi-step process that requires the
polymerization of a reactant mixture (a) in a solvent mixture (b). Solvent
mixture (b)
will comprise at least one nonvolatile solvent (b"~) having at least one
functional group
(F1). The polymerization of reactant mixture (a) into polymer (a') occurs
either ,
before, after, or simultaneously with the reaction of functional group (Fl) of
the
nonvolatile solvent (b"~) with at least one reactant (e) to provide a
nonvolatile solvent
(b'"~) having at least two functional groups (F2). That is, at least two
separate
reactions must occur. The reactant mixture (a) is subjected to polymerization
conditions sufficient to polymerize reactant mixture (a) to provide a polymer
(a'). The
nonvolatile solvent (b"~) is subj ected to reaction conditions wherein the at
least one
functional group (Fl) of nonvolatile solvent (b"~) is reacted with at least
one reactant
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(e) to provide a nonvolatile solvent (b'n~) comprising at least two functional
groups
(F2). In one exemplary embodiment, the two reactions will occur
simultaneously.
However, it is also possible for either of the two reactions to occur first,
so long as
both reactions occur at some point prior to the obtainment of mixture (II). It
will thus
be appreciated that the at least one functional group (F1) is not and may not
be the
same as functional groups (F2).
[0023] Solvent mixture (b) in which reactive mixture (a) is polymerized
comprises a particular nonvolatile solvent (b",,) that must be substantially
inert in three
ways to under the polymerization conditions to which reactant mixture (a) is
subjected. "Substantially inert" as used herein refers to a degree of reaction
between
the nonvolatile solvent (b"~) and the reaction mixture (a) of less than 3 % of
the total
functionality of nonvolatile solvent (b"~), preferably less than 2%, and most
preferably
less than 1 % of the total functionality of nonvolatile solvent (b,,"). Total
functionality
as used herein does not include nonaromatic alkenyl groups and reactions of
extractable hydrogens. "Extractable hydrogens" as used herein refers to
hydrogens
attached to either carbon of a carbon-caxbon double bond in a nonaromatic
alkenyl
group.
[0024] In a most preferred embodiment, any reaction between nonvolatile
solvent (b"~) and reaction mixture (a) will be attributable solely to the
presence of
unwanted impurities and/or contaminants in nonvolatile solvent (b"~).
Reactions with
any nonaromatic alkenyl groups or extractable hydrogens in nonvolatile solvent
(b"~)
are considered to be within the scope of unwanted impurities and/or
contaminants in
nonvolatile solvent (b"~).
[0025] First, the nonvolatile solvent (b"~) must be substantially inert or
nonreactive with any functional groups on components of reactant mixture (a)
under
the polymerization conditions. Thus, nonvolatile solvent (b"~) must generally
be free
of any functional groups that are reactive with one or more functional groups
of the
components of reactant mixture (a) under the conditions used to polymerize
reactant
mixture (a) including free radical reactions or otherwise. Functional groups
(Fl) of
nonvolatile solvent (b"~) will thus normally be free of any groups that are
reactive with
one or more functional groups of the components of reactant mixture (a) under
conditions used to polymerize reactant mixture (a). Functional group (Fl) of
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nonvolatile solvent (b"~) thus does not include nonaromatic alkenyl groups or
extractable hydrogens.
[0026] Second, the nonvolatile solvent (bn~) must be substantially inert or
nonreactive during the polymerization of reactant mixture (a). That is,
nonvolatile
solvent (b"~) may not polymerize under the polymerization conditions that
result in the
transformation of reactant mixture (a) into polymer (a').
[0027] Finally, the nonvolatile solvent (b"~) must be substantially inert or
nonreactive with the resulting polymer (a') while under the polymerization
conditions
used to polymerize reactant mixture (a). For example, if an epoxy functional
component and an acid functional component are polymerized to provide an epoxy
upgrade polymer, the nonvolatile solvent (b"~) may not have any functional
groups
reactive with the secondary hydroxyl formed by the ring opening of the oxirane
functional group.
[0028] In one exemplary embodiment, the functional group (F1) of nonvolatile
solvent (b"~) is limited to those functional groups which may be on one or
more
components of reactant mixture (a) but which do not enter into the
polymerization of
reactant mixture (a) or any graft polymerization processes involving reactant
mixture
(a) or polymer (a'). The at least one functional group (Fl) of nonvolatile
solvent (b"~)
does not include nonaromatic alkenyl groups or exixactable hydrogens.
[0029] Polymer (a') may be any polymer, oligomer or mixture thereof,
resulting from the polymerization of reactant mixture (a). As used herein
polymer (a')
may generally have a number average molecular weight of from 400 to 50,000
Daltons. Usually, the polymer (a') will have a number average molecular weight
of
from 1000 to 50,000 Daltons. Polymer (a') may be an acrylic polymer, a
polyurethane
polymer, a polyester polymer, an epoxy upgrade polymer, a dendrimer polymer,
or the
like. In one exemplary embodiment, polymer (a') will be an acrylic polymer, a
polyurethane polymer, or a polyester polymer. In one especially exemplary
embodiment, polymer (a') will be an acrylic polymer or a polyurethane polymer,
with
acrylic polymers being especially preferred.
[0030] It will be appreciated that the composition of reactant mixture (a)
will
depend upon the desired type of polymer (a'). In general, reactant mixture (a)
will be
comprised of one or more components, preferably two or more components that
can
be subjected to polymerization conditions to produce a polymer (a'). More
preferably
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the component of reactant mixture (a) will be monomers or compounds that can
react
with each other and/or compounds produced therefrom, to provide a polymer of
increased molecular weight relative to the initial starting reactants of
reactant mixture
(a).
[0031] The polymerization of reactant mixture (a) to polymer (a') may be
heterogenous, i.e., aqueous emulsion or nonaqueous dispersion, or homogenous,
i.e.,
solution polymerization. Homogenous polymerization process are preferred.
[0032] If polymer (a') is an acrylic polymer, reactant mixture (a) will be
comprised of ethylenically unsaturated monomers having at least one carbon-
carbon
double bond able to undergo free radical polymerization.
[0033] Illustrative ethylenically unsaturated monomers include, without
limitation, alpha, beta-ethylencally unsaturated monocarboxylic acids
containing 3 to
5 carbon atoms such as acrylic, methacrylic, and crotonic acids, and the
esters, nitriles,
and amides of those acids; alpha, beta-ethylenically unsaturated dicarboxylic
acids
containing 4 to 6 carbon atoms and the anhydrides, monoesters, and diesters of
those
acids; vinyl esters, vinyl ethers, vinyl ketones, and aromatic or heterocylic
aliphatic
vinyl compounds. Carbamate functional ethylenically unsaturated monomers,
cyclic
carbonate functional ethylenically unsaturated monomers, and/or isocyanate
functional
ethylenically unsaturated monomers may also be used, most preferably in
combination
with other ethylenically unsaturated monomers.
[0034] Representative examples of suitable esters of acrylic methacrylic, and
crotonic acids include, without limitation, those esters from reaction with
saturated
aliphatic and cycloaliphatic alcohols containing 1 to 20 carbon atoms, such as
methyl,
ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, lauryl,
stearyl,
cycolhexyl, trimethylcyclohexyl, tetrahydrofurfuryl, stearyl, sulfoethyl, and
isobornyl
acrylates, methacrylates, and crotonates; and polyalkylene glycol acrylates
and
methacrylates.
[0035] Representative examples of other ethylenically unsaturated
polymerizable monomers include, without limitation, such compounds as fumaric,
malefic, and itacoiuc anhydrides, monoesters, and diesters with alcohols such
as
methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and tert-
butanol.
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[0036] Representative examples of polymerizable vinyl monomers include,
without limitation, such compounds as vinyl acetate, vinyl propionate, vinyl
ethers
such as vinyl ethyl ether, vinyl and vinylidene halides, and vinyl ethyl
ketone.
[0037] Representative examples of aromatic or heterocylic aliphatic vinyl
compounds include, without limitation, such compounds as styrene, alpha-methyl
styrene, vinyl toluene, tent-butyl styrene, and 2-vinyl pyrrolidone.
[0038] Representative examples include acrylic and methacrylic acid amides
and aminoalkyl amides, acrylonitrile, and methacrylonitriles.
[0039] Other suitable examples include acrylates or methacrylates having
hydroxy, epoxy, or other functional groups, such as hydroxyalkyl acrylates and
methacrylates, glycidyl esters of methacrylic and acrylic acid such as
glycidyl
methacrylate, and aminoalkyl esters of methacrylic or acrylic acid like N,N-
dimethylaminoethyl (meth)acrylate.
[0040] Acrylic monomers having carbamate functionality in the ester portion
of the monomer are well known in the art and are described, for example in
U.S.
Patents 3,479,328, 3,674,838, 4,126,747, 4,279,833, and 4,340,497, 5,356,669,
and
WO 94/10211, the disclosures of which are incorporated herein by reference.
One
method of synthesis involves reaction of a hydroxy ester with urea to form the
carbamyloxy carboxylate (i.e., carbamate-modified acrylic). Another method of
synthesis reacts an oc,(3-unsaturated acid ester with a hydroxy carbamate
ester to form
the carbamyloxy carboxylate. Yet another technique involves formation of a
hydroxyalkyl carbamate by reacting a primary or secondary amine or diamine
with a
cyclic carbonate such as ethylene carbonate. The hydroxyl group on the
hydroxyalkyl
carbamate is then esterified by reaction with acrylic or methacrylic acid to
form the
monomer. Other methods of preparing carbamate-modified acrylic monomers are
described in the art, and can be utilized as well. The acrylic monomer can
then be
polymerized along with other ethylenically unsaturated monomers, if desired,
by
techniques well known in the art.
[0041] Ethylenically unsaturated isocyanate monomers are well-known in the
art and include meta-isopropenyl-.alpha.,.alpha.-dimethylbenzyl isocyanate
(sold by
American Cyanamid as TMI~) and isocyanatoethyl methacrylate.
[0042] Cyclic carbonate ethylenically unsaturated monomers are well-known
in the art and include (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate.
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[0043] When polymer (a') is an acrylic resin, it will generally have a number
average molecular weight of from 1000 to 50,000, preferably from 10,000 to
25,000,
with molecular weights of from 15,000 to 20,000 being most preferred.
[0044] In a preferred embodiment, polymer (a') will be a hydroxyl or
carbamate functional resin which may or may not be water dispersible. For
example,
in one preferred embodiment, polymer (a') will be a water dispersible acrylic
polymer
having a hydroxyl equivalent weight of from 250 to 1500 g/mole and an acid
equivalent weight of from 500 to 3000 g/mole. In another preferred embodiment,
the
polymer (a') will be a water dispersible acrylic polymer having a carbamate
equivalent
weight of from 250 to 1500 g/mole and an acid equivalent weight of from 500 to
3000
g/mole. In another preferred embodiment, the polymer (a') is an acrylic
polymer
having a hydroxyl equivalent weight of from 250 to 1500 g/mole and an acid
equivalent weight greater than 3000 g/mole. Finally, in another preferred
embodiment, the polymer (a') is an acrylic polymer having a carbamate
equivalent
weight of from 250 to 1500 g/mole and an acid equivalent weight greater than
3000
g/mole.
[0010] In one embodiment, the ethylenically unsaturated monomers of reactant
mixture (a) will be polymerized to provide an acrylic polymer (a') having one
or
more functional groups (Fo) that are subsequently converted to functional
groups
(F3) via reaction with one or more reactants (e'). Functional groups (Fo) in
this
embodiment must comprise at least one functional group convertible to a
primary
carbaxnate group or to intermediate a functional group (Fo) convertible to a
group
convertible to a primary carbamate group. Examples of suitable functional
groups
(Fo) include primary and secondary hydroxyl groups, acid groups, epoxy groups,
amine groups, carbonate groups, isocyanate groups, and the like. However, it
will
lie appreciated that in each case, the 'substantial inertness' of nonvolatile
solvent
(b"~), reactant mixture (a) and resin (a') must be maintained. In one
exemplary
embodiment, the ethylenically unsaturated monomers of reactant mixture (a) may
comprise primary or secondary hydroxyls as well as mixtures of both, i.e.,
hydroxyl
ethyl methyacrylate, hydroxyl propyl methacrylate, and the lilce, as well as
mixtures
thereof. In another exemplary embodiment, reactant mixture (a) will comprise
glycidyl esters of acrylic and methacrylic acid so that functional groups (Fo)
will be
epoxy.
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[0011] The conversion of functional group (Fo) to a functional group (F3) that
is at
least one of primary carbamate, primary hydroxyl, secondary hydroxyl or
mixtures
thereof may be done via reaction with a reactant (e').
[0012] For example, hydroxyl functional groups (F3) or intermediate hydroxyl
functional groups may be obtained by the ring opening of an epoxy functional
group
(Fo) with an acid functional reactant (e'). When only one epoxy functional
group (Fo)
is present, acid functional reactant (e') must have an additional functional
group such
as hydroxyl, carbamate, urea, amide, and the like.
[0013] In another example, carbamate functional groups (F3) may be obtained
via
the reaction of hydroxyl functional groups (Fo) with a reactant (e') selected
from
low molecular weight carbamate functional monomers such as methyl carbamate.
Alternatively, carbamate functional groups (F3) may be made by decomposing a
reactant (e) such as urea in the presence of hydroxyl functional groups (Fo).
Finally, in another embodiment, carbamate.functional groups (F3) may be
obtained
by reacting a first reactant (e') such as phosgene with a hydroxyl functional
group
(Fo) followed by reaction with another reactant (e') such as ammonia.
[0014] Epoxy functional groups (Fo) useful as an intermediate functional group
may be made via reaction of acid functional groups (Fo) with a reactant (e')
such as
peroxide. Alternatively, epoxy functional groups (F3) will be obtained via the
reaction of acid or hydroxyl functional groups (Fo) with a reactant (e') such
as
epichlorohydrin.
[0015] Cyclic carbonate functional groups (Fo) useful as an intermediate
functional
group may be made via reaction of an epoxy functional group (Fo) with a
reactant
(e') such as carbon dioxide.
[0016] It will thus be appreciated that in one exemplary embodiment, reactant
(e')
may be at least one of low molecular weight carbamate functional reactants
(such as
simple alkyl carbamates), urea, phosgene, ammonia, carbon dioxide, acids,
aldehydes,
alcohols, peroxides, epichlorohydrin, mixtures thereof, and the like. In
another
exemplary embodiment, when functional group (Fo) is hydroxyl, reactant (e')
may be
an allcyl carbamate, urea, or phosgene and ammonia. In one especially
exemplary
embodiment, reactant (e') will be an alkyl carbamate when functional group
(Fo) is
hydroxyl.
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[0017] The reaction conditions suitable for the reaction of functional groups
(Fo)
with at least one reactant (e') will generally be known to those of skill in
the art.
[0125] In another embodiment, the reaction mixture (a) will comprise
ethylenically
unsaturated monomers having carbamate functionality in the ester portion of
the
monomer. Acrylic monomers having carbamate functionality in the ester portion
of
the monomer are well known in the art and are described, for example in U.S.
Patents
3,479,328, 3,674,838, 4,126,747, 4,279,833, 4,340,497, and 5,356,669, and WO
94/10211, the disclosures of which are incorporated herein by reference. One
method
of synthesis involves reaction of a hydroxy ester with urea to form the
carbamyloxy
carboxylate (i.e., carbamate-modified acrylic). Another method of synthesis
reacts an
a,(3-unsaturated acid ester with a hydroxy carbamate ester to form the
carbamyloxy
carboxylate. Yet another technique involves formation of a hydroxyalkyl
carbamate
by reacting a primary or secondary amine or diamine with a cyclic carbonate
such as
ethylene carbonate. The hydroxyl group on the hydroxyalkyl caxbamate is then
esterified by reaction with acrylic or methacrylic acid to form the monomer.
Other
methods of prepat~ing carbamate-modified acrylic monomers are described in the
art,
and can be utilized as well. The acrylic monomer can then be polymerized along
with
other ethylenically unsaturated monomers, if desired, by techuques well known
in the
art
[0045] If polymer (a') is a polyester, reactant mixture (a) will be comprised
of
a mixture of at least one polycarboxylic acid and/or anhydride, and at least
one polyol
and/or epoxide. Such reactants will be subjected to polymerization via
esterification.
[0046] In one embodiment, the polycarboxylic acids used to prepare a
polyester polymer (a') will generally be monomeric polycarboxylic acids or
anhydrides thereof having 2 to 18 carbon atoms per molecule. Among useful
acids are
phthalic acid, hexahydrophthalic acid, adipic acid, sebacic acid, malefic
acid, and other
dicarboxylic acids of various types. Minor amounts of monobasic acids can be
included in the reaction mixture (a'), for example, benzoic acid, stearic
acid, acetic
acid, and oleic acid. Also, higher carboxylic acids can be used, for example,
trimellitic acid and tricarballylic acid. Anhydrides of the acids referred to
above,
where they exist, can be used in place of the acid. Also, lower alkyl esters
of the acids
can be used, for example, dimethyl glutarate and dimethyl terephthalate.
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[0047] Polyols that can be used to prepare a polyester polymer (a') include
diols such as alkylene glycols. Specific examples include ethylene glycol, 1,6-
hexanediol, neopentyl glycol, and 2,2-dimethyl-3-hydroxypropionate. Other
suitable
glycols include hydrogenated bisphenol A, cyclohexanediol,
cyclohexanedimethanol,
caprolactone-based diols such as the reaction product of e-caprolactone and
ethylene
glycol, hydroxy-alkylated bisphenols, polyether glycols such as
poly(oxytetramethylene)glycol, mixtures thereof and the like.
[0048] Although the polyol component of reactant mixture (a) can be
comprised of all diols, polyols of higher functionality can also be used. In
one
exemplary embodiment, the polyol component will be a mixture comprising at
least
one diol, and at least one polyol of higher functionality such as a triol.
Examples of
polyols of higher functionality would include trimethylol ethane, trimethylol
propane,
pentaerythritol, and the like. Triols are preferred. In one exemplary
embodiment, the
mole ratio of polyols of higher functionality to diol is less than 3.3/1,
preferably up to
1.4/1. Limited amounts of monofunctional alcohols, such as ethylhexanol, may
also
be used.
[0049] Polyurethane polymers (a') may be prepared by the polymerization of
a reactant mixture (a) comprising at least one di- and/or polyisocyanate and
at least
one polyol. They are prepared by a chain extension reaction of a
polyisocyanate (e.g.,
hexamethylene diisocyanate, isophorone diisocyanate, MDI, etc.) and an active
hydrogen-containing chain extension agent, such as a polyol. They can be
provided
with active hydrogen functional groups by capping the polyurethane chain with
an
excess of diol, polyamine, amino alcohol, or the like that are included in
reactant
mixture (a).
[0050] For example, suitable polyisocyanates can be an aliphatic
polyisocyanate, including a cycloaliphatic polyisocyanate or an aromatic
polyisocyanate. Useful aliphatic polyisocyanates include aliphatic
diisocyanates such
as ethylene diisocyanate,1,2-diisocyanatopropane,1,3-diisocyanatopropane,1,6-
diisocyanatohexane,1,4-butylene diisocyanate, lysine diisocyanate,1,4-
methylene bis-
(cyclohexyl isocyanate) and isophorone diisocyanate. Useful aromatic
diisocyanates
and araliphatic diisocyanates include the various isomers of toluene
diisocyanate,
meta-xylenediisocyanate and para-xylenediisocyanate, also 4-chloro-1,3-
phenylene
diisocyanate,1,5-tetrahydro-naphthalene diisocyanate, 4,4'-dibenzyl
diisocyanate and
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WO 2005/123787 PCT/US2005/020611
1,2,4-benzene triisocyanate can be used. In addition, the various isomers of
a.', a,', a,',
a,-tetramethyl xylylene diisocyanate can be used. Also useful as the
polyisocyanate
are isocyanurates such as DESMODUR~ N 3300 from Mobay and biurets of
isocyanates such as DESMODUR~ N100 from Mobay.
[0051] Active hydrogen-containing chain extension agents generally contain
at least two active hydrogen groups, for example, diols, dithiols, diamines,
or
compounds having a mixture of hydroxyl, thiol, and amine groups, such as
alkanolamines, aminoalkyl mercaptans, and hydroxyalkyl mercaptans, among
others.
Both primary and secondary amine groups are considered as having one active
hydrogen. Active hydrogen-containing chain extension agents also include
water. In
one preferred embodiment of the invention, a polyol is used as the chain
extension
agent, to provide a polyurethane. Illustrative polyols are those as described
above
with respect to polyesters polymers (a'). In an especially preferred
embodiment, a diol
is used as the chain extension agent with little or no higher polyols, to
minimize
branching. In one exemplary embodiment, illustrative polyols include 1,6
hexanediol,
cyclohexanedimethylol, and 1,4-butanediol. While polyhydroxy compounds
containing at least three hydroxyl groups may be used as chain extenders, the
use of
these compounds produces branched polyurethane resins. These higher functional
polyhydroxy compounds include, for example, trimethylolpropane,
trimethylolethane,
pentaerythritol, among other compounds.
[0052] Monofunctional capping alcohols such as 2-ethylhexanol may also be
used. The mono- or polyfunctional alcohol may contain additional functional
groups.
Non-limiting examples are glycidol, hydroxyalkylcarbamates such as hydroxy
ethyl
carbamate or hydroxy butyl carbamate, and hydroxy acids such as 1-
hydroxybutylic
acid.
[0053) The polyurethane polymer (a') may be chain extended in any manner
using those compounds having at least two active hydrogen groups.
Accordiilgly,
reactant mixture (a) may thus include a mixture of polyisocyanate, polyol, and
multi-
functional compounds.
[0054] In one especially exemplary embodiment, the reactant mixture (a) is
present in a mixture (I) with a solvent mixture (b) that comprises a
nonvolatile solvent
(b"~). In one exemplary embodiment, the reactant mixture (a) will be soluble
in
nonvolatile solvent (b"v).
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[0055] Illustrative examples of suitable nonvolatile solvents (b"~) are
generally
those materials that may be an amorphous solid, wax, or liquid at room
temperature
but are nonetheless a fluid solid at the temperature that the polymerization
reaction of
reactant mixture (a) occurs. "Nonvolatile" as used herein refers to materials
having a
boiling point at least 100°C, preferably 200°C, most preferably
300°C, above the
polymerization temperature. A "fluid solid" refers to a nonvolatile material
that has a
viscosity similar to a traditional solvent at the polymerization temperature.
[0056] In one embodiment, the nonfunctional part of suitable nonvolatile
solvents (b"~) will have from 8 to 300 carbons. In another embodiment,
nonvolatile
solvent (b"~) will be have at least one functional group (F1), while in one
exemplary
embodiment; nonvolatile solvent (bn~) will have at least two functional groups
(F1). In
another embodiment, nonvolatile solvent (b"~) will be substantially free of
heteroatoms
as discussed below.Other illustrative examples for suitable nonvolatile
solvents (b"v )
include diethyl octanediol, neodecanoic acid, the glycidyl ester of
neodecanoic acid,
the cyclic carbonate of the glycidyl ester of neodecanoic acid, alpha
polyolefmpolyols,
alpha polyolefm polyacids, and the like.
[0057] In another embodiment, suitable nonvolatile solvents (b"~) may also
comprise heteroatom containing linking groups, i.e. containing atoms other
than
carbon or hydrogen. Illustrative examples of such heteroatom containing
linking
groups include ethers, ureas, esters, urethanes, silanes and the like.
[0058] In one especially exemplary embodiment, the nonvolatile solvent (b"~)
will be a reactive component (c). In one embodiment, the non-functional part
of
reactive component (c) will have from 12 to 72. carbons, more preferably from
18 to
54 carbons, and most preferably from 36 to 54 carbons. In one particularly
exemplary
embodiment, the nonfunctional part of reactive component (c) will have 36
carbons
and at least two functional groups (Fl).
[0059] In one exemplary embodiment, reactive component (c) will be
substantially free of heteroatoms. ''Heteroatom" as used herein refers to
atoms other
than carbon or hydrogen. The phrase "substantially without" heteroatoms as
used
herein means that the portion of reactive component (c) which does not include
functional groups (F1) will generally have no more than two atoms which are
other
than carbon or hydrogen, i.e., atoms such as N, O, Si, mixtures thereof, and
the lilce.
More preferably, that portion of reactive component (c) that does not include
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WO 2005/123787 PCT/US2005/020611
functional groups (F1) will have no more than two atoms that are other than
carbon or
hydrogen. In a particularly exemplary embodiment, that portion of reactive
component (c) that does not include functional groups (F1) will have no
heteratoms,
i.e., will consist solely of carbon and hydrogen atoms. Thus, in a most
preferred
aspect of the invention, the only heteratoms in reactive component (c) will be
present
in functional groups (Fl).
[0060] In one exemplary embodiment, reactive component (c) will not be a
crystalline solid at room temperature, i.e., at temperatures of from 65 to
75°F.
"Crystalline" refers to a solid characterized by a regular, ordered
arrangement of
particles. Rather, iil this embodiment, reactive component (c) will be an
amorphous
solid, a wax or a liquid at room temperature. "Amorphous" refers to a
noncrystalline
solid with no well-defined ordered structure.
[0061] liz another exemplary embodiment, reactive component (c) will
comprise a mixture of two or more saturated or unsaturated structures selected
from
the group consisting of noncyclic structures for reactive component (c),
aromatic-
contaiiung structures for reactive component (c), cyclic-containing structures
for
reactive component (c), and mixtures thereof. Saturated structures are
preferred,
especially where durability issues are of concern. For example, a most
preferred
reactive component (c) will comprise a mixture of two or more structures
selected
from the group consisting of aliphatic structures for reactive component (c),
aromatic-
containing structures for reactive component (c), cycloaliphatic-containing
structures
for reactive component (c), and mixtures thereof.
[0062] It is particularly preferred that reactive component (c) comprise at
least
two, more preferably three, of the three cited structures. If reactive
component (c)
comprises only two of the three cited structures for reactive component (c),
then at
least one of the two structures must be present as a mixture of two or more
isomers
thereof.
[0063] For example, the mixture of reactive components (c) may comprise at
least one aliphatic structure for reactive component (c) and at least one
other structure
for reactive component (c) selected from the group consisting of aromatic-
containing
structures for reactive component (c), cycloaliphatic-containing structures
for reactive
component (c), and mixtures thereof. If the 'at least one other structure for
reactive
component (c)' is not a mixture of aromatic-containing structures for reactive
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component (c) and cycloaliphatic-containing structures for reactive component
(c),
either the aromatic-containing structures or the cycloaliphatic containing
structures
must be present as a mixture of two or more isomers.
(0064] Alternatively, the mixture of reactive components (c) may comprise at
least one aromatic-containing structure for reactive component (c) and at
least one
other structure for reactive component (c) selected from the group consistiizg
of
aliphatic structures for reactive component (c), cycloaliphatic-containing
structures for
reactive component (c), and mixtures thereof. If the 'at least one other
structure for
reactive component (c)' is not a mixture of aliphatic structures for reactive
component
(c) and cycloaliphatic-containiizg structures for reactive component (c),
either the
aliphatic structures or the cycloaliphatic containing structures must be
present as a
mixture of two or more isomers.
[0065] In a most preferred embodiment, reactive component (c) will comprise
one or more aliphatic structures for reactive component (c), one or more
aromatic-
containing structures for reactive component (c), and one or more
cycloaliphatic-
containing structures for reactive component (c). Particularly advantageous
mixtures
of reactive component (c) will comprise from 3 to 25% by weight of reactive
component (c) having an aliphatic structure, from 3 to 25% by weight of
reactive
component (c) having an aromatic-containing structure, and 50 to 94% by weight
of
reactive component (c) having a cycloaliphatic-containing structure. More
preferred
mixtures of reactive component (c) will comprise from 3 to 18% by weight of
reactive
component (c) having an aliphatic structure, from 5 to 23% by weight of
reactive
component (c) having an aromatic-containing structure, and 55 to 85% by weight
of
reactive component (c) having a cycloaliphatic-containing structure. Most
preferred
mixtures of reactive component (c) will comprise from 5 to 10% by weight of
reactive
component (c) having an aliphatic structure, from 10 to 20% by weight of
reactive
component (c) having an aromatic-containing structure, and 60 to 70% by weight
of
reactive component (c) having a cycloaliphatic-containing structure.
[0066] In one exemplary embodiment, reactive component (c) will comprise
at least two functional groups (FI) per molecule. Preferred reactive
components (c)
may have from two to six functional groups (F1) while most preferably reactive
component (c) will have two to three functional groups (Fl).
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WO 2005/123787 PCT/US2005/020611
[0067] Functional groups (Fl) of nonvolatile solvent (bn~) may be selected
from a variety of active hydrogen containing groups and groups reactive with
such
active hydrogen containing groups. Examples of illustrative functional groups
(F1) are
hydroxy, isocyanate (blocked or unblocked), epoxy, carbamate, aminoplast,
aldehyde,
acid, epoxy, amine, cyclic carbonate, urea, mixtures thereof, and the like.
[0068] Preferred functional groups (Fl) are hydroxyl both primary and
secondary, primary carbamate, isocyanate, amiizoplast functional groups,
epoxy,
carboxyl and mixtures thereof. Most preferred functional groups (F1) are
secondary
hydroxyl, primary carbamate, and mixtures thereof, with primary carbamate
groups
being particularly preferred.
[0069] Illustrative examples of suitable nonvolatile solvents (b"~) having
functional groups (F1) wluch are carboxyl are fatty acids and addition
reaction
products thereof, such as dimerized, trimerized and tetramerized fatty acid
reaction
products and higher oligomers thereof. Suitable acid functional dimers and
higher
oligomers may be obtained by the addition reaction of Cla-is monofunctional
fatty
acids. Suitable monofunctional fatty acids may be obtained from Cognis
Corporation
of Ambler, PA. Such materials will be acid functional and will contain some
unsaturation. In addition, saturated and unsaturated dimerized fatty acids are
commercially available from Uniqema of Wilmington, DE.
[0070] Hydroxyl functional nonvolatile solvents (b"~) are commercially
available as the Pripol~ saturated fatty acid dimer (PripolTM 2033) supplied
by
Uniqema of Wilmington, DE. Hydroxyl functional nonvolatile solvents (b"~) may
also
be obtained by reduction of the acid group of the above-discussed fatty acids.
[0071] Nonvolatile solvents (b"~) having two or more carbamate functional
groups may be obtained via the reaction of the hydroxyl functional nonvolatile
solvents (b"~) with a low molecular weight carbamate functional monomer such
as
methyl carbamate under appropriate reaction conditions. Alternatively,
carbamate
functional nonvolatile solvents (b"~) may be made via decomposition of urea in
the
presence of hydroxyl functional nonvolatile solvents (b"~) as described above.
Finally,
carbamate functional nonvolatile solvents (b"~) can be obtained via the
reaction of
phosgene with the hydroxyl functional nonvolatile solvents (b"~) followed by
reaction
with ammonia.
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[0072] Amine groups suitable for use as functional group (F1) may be primary
or secondary, but primary amines are most preferred. Nonvolatile solvents
(bn~)
having amine functional groups (F1) may be obtained via reaction of the acid
functional nonvolatile solvents (b"~) to form an amide, followed by conversion
to a
nitrite and subsequent reduction to an amine.
[0073] Nonvolatile solvents (b"V) having isocyanate functional groups (Fl)
may be obtained via reaction of the amine functional nonvolatile solvent (b"~)
described above with carbon dioxide.
[0074] Aminoplast functional groups may be defined as those functional
groups resulting from the reaction of an activated amine group and an aldehyde
or
formaldehyde. Illustrative activated amine groups are melamine,
benzoguanamine,
amides, carbamates, and the like. The resulting reaction product may be used
directly
as functional group (F1) or may be etherified with a monofunctional alcohol
prior to
use as functional group (Fl).
[0075] Nonvolatile solvents (b"~) having aminoplast functional groups (F1)
may be made via reaction of carbamate functional nonvolatile solvents (bn~) as
described above with formaldehyde or aldehyde. The resulting reaction product
may
optionally be etherified with low boiling point alcohols.
[0076] Nonvolatile solvents (b"~) having aldehyde functional groups (Fl) may
be made via reduction of the acid functional nonvolatile solvents (b"~)
described
above.
[0077] Nonvolatile solvents (b"~) having urea functional groups (Fl) may be
made via reaction of an amine functional nonvolatile solvent (b"~) with urea.
Alternatively, amine functional nonvolatile solvents (b"~) can be reacted with
phosgene followed by reaction with ammonia to produce the desired urea
functional
groups (F1).
[0078] Nonvolatile solvents (b",,) having epoxy functional groups (Fl) may be
made using either saturated or unsaturated fatty acids described above. If an
unsaturated fatty acid is used, reaction with peroxide will form internal
epoxy groups.
More preferably, an acid or hydroxyl functional nonvolatile solvents (b"~)
will be
reacted with epichlorohydrin. Preferred epoxy functional nonvolatile solvents
(b"~)
will be obtained using saturated starting materials.
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[0079] Nonvolatile solvents (b"~) having cyclic carbonate iunctionai groups
(F1) may be made via carbon dioxide insertion into an epoxy functional
nonvolatile
solvents (b"~) as described above.
[0080] In one exemplary embodiment, nonvolatile solvents (b"~) will comprise
one or more of the following structures:
0
h ~~ NHZ NH,,
R R
NHa
p~NH2 D~NHZ
n
OII
O~NHZ NHz
R
R=C5-C$
[0081] As discussed above, in one exemplary embodiment, nonvolatile
solvent (b"~) will be substantially nonreactive under the polymerization
conditions:
(1) with the components of reactive mixture (a), (2) in the polymerization of
reactant
mixture (a) and (3) with the polymer (a'). Thus, the functional groups (Fl) of
nonvolatile solvents (b"~) discussed above must be selected so as not to
participate in
the polymerization reaction of reactant mixture (a). The functional groups
(Fl) must
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WO 2005/123787 PCT/US2005/020611
also not react with any of the functional groups of the components reactant
mixture (a)
and/or on polymer (a').
[0082] For example, when nonvolatile solvent (b"~) is used in a free radical
acrylic polymerization where reactive mixture (a) comprises an isocyanate
functional
monomer, the functional groups (Fl) of nonvolatile solvent (b"~) may not be
hydroxy
or amine. When high polymerization temperatures are used in an embodiment,
(such
as 140°C), functional group (F1) of nonvolatile solvents (b"~) may not
be acid
functional.
[0083] Alternatively, when nonvolatile solvents (b"~) is used in an
embodiment employing an ionic or similar polymerization, the level of non-
aromatic
unsaturated groups on nonvolatile solvent (b"~) must be minimized, preferably
to a
level of less than 5 weight percent, more preferably less than 2 weight
percent, based
on the total weight of nonvolatile solvents (b"~). In another example,
functional
groups (F1) should not contain any groups that would react with the isocyanate
or
active proton source (usually hydroxy) when the nonvolatile solvents (b"~) is
used in a
urethane polymerization. The typical functional groups on nonvolatile solvents
(b"~)
that should be avoided in this case are hydroxy and amine groups. Other
functional
groups on nonvolatile solvents (b"V) might also have to be avoided depending
on the
nature of any functional groups on the active hydrogen material. For example,
if
glycidol is used as a capping group in the urethane polymerization, the
nonvolatile
solvents (b"~) must be free of acid groups.
[0084] When the nonvolatile solvents (b"~) is used in a polyester
polymerization, functional groups (Fl) should not be any groups that will
react with
anhydrides, acids, and alcohols. Examples of such groups to be avoided include
acids,
hydroxy, epoxy, unblocked isocyanates and the like. In such as case, non-
limiting
examples of functional groups (Fl) of nonvolatile solvents (bn~) would be
carbamate,
vinyl or mixtures thereof.
[0085] Finally, it is within the scope of the invention that nonvolatile
solvents
(b'"~) may have functional groups that are also reactive with polymer (a')
when
exposed to cure conditions, but axe inert during polymerization conditions. A
non-
limiting example of this would be use of a ketamine functionalized nonvolatile
solvent
(b'"~) with an epoxy, cyclic carbonate and/or isocyanate functional acrylic
polymer.
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[0086] In addition to nonvolatile solvent (b"~) or nonvolatile solvent (b'"~),
solvent mixture (b) may further comprise other solvents and/or cosolvents such
as
water and/or organic solvents. Illustrative solvents include aromatic
hydrocarbons,
such as, petroleum naphtha or xylenes, ketones such as methyl amyl ketone,
methyl
isobutyl ketone, methyl ethyl ketone or acetone; esters such as butyl acetate
or hexyl
acetate; and glycol ether esters, such as propylene glycol monomethyl ether
acetate.
Other examples of useful solvents include, without limitation, m-amyl acetate,
ethylene glycol butyl ether-acetate, xylene, N-methylpyrrolidone, blends of
aromatic
hydrocarbons, and mixtures of these.
[0087] In one embodiment, solvent mixture (b) will comprise from 0 to 95
by weight of nonvolatile solvent (b"~), in another embodiment, from 0 to 75 %
by
weight, and in a particularly exemplary embodiment, from 0 to 20 % by weight,
all
based on the total weight of solvent mixture (b).
[0088] Coating compositions of the invention will comprise a mixture (II)
made by the method of the invention wherein mixture (II) comprises polymer
(a') and
the solvent mixture (b) comprising a nonvolatile solvent (b'"~). Coating
compositions
of the invention may further comprise other known film-forming binders not
made by
the method of the invention, but most preferably will not. Illustrative
examples of
other binders that bay be used in addition to polymer (a') include acrylic
polymers,
polyurethane polymers, polyester polymers, epoxy functional polymers, mixtures
thereof, and the lilce.
[0089] In general, coating compositions of the invention will comprise from
10 to 90 % by weight nonvolatile of polymer (a'), more preferably from 20 to
80 % by
weight nonvolatile of polymer (a') and most preferably from 40 to 60 % by
weight
nonvolatile of polymer (a'), based on the total weight of the total
nonvolatile of the
coating composition.
[0090] For the coating compositions of the invention, solvent mixture (b) will
generally have from 5 to 100 % by weight of nonvolatile solvent (b'"~), more
preferably from 30 to 100 % by weight of nonvolatile solvent (b'"~), and most
preferably from 80 to 100 % by weight of nonvolatile solvent (b'"~), all based
on the
total weight of solvent mixture (b).
[0091] Nonvolatile solvent (b"~) is reacted with at least one reactant (e) to
provide a nonvolatile solvent (b'"~) comprising at least two functional groups
(Fa). As
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WO 2005/123787 PCT/US2005/020611
previously indicated, such reactions may occur before, during or after the
polymerization of reactant mixture (a) to polymer (a'). W one exemplary
embodiment, the reaction of nonvolatile solvent (b"~) with at least one
reactant (e) will
occur during and after the polymerization of reactant mixture (a).
[0092] In one exemplary embodiment, functional group (F2) will be any one
of a pair of reactants that would result in a thermally irreversible chemical
linkage
upon reaction with a crosslinking agent (f). The term "thermally irreversible
liilkage"
refers to a linkage the reversal of which is not thermally favored under the
traditional
cure schedules used for automotive coating compositions. Illustrative examples
of
suitable thermally irreversible chemical linkages are urethanes, areas, esters
and
ethers. Preferred thermally irreversible chemical linkages are urethanes,
areas and
esters, with urethane linkages being most preferred. Such chemical linkages
will not
break and reform during the crosslinking process as is the case with the
linkages
formed via reaction between hydroxyl groups and aminoplast resins.
[0093] It will be appreciated that in this exemplary embodiment, if one
member of a "pair" is selected for use as functional group (F2), the other
member of
the "pair" will generally be selected as functional group (fi) of crosslinking
agent (f)
discussed below. Examples of illustrative reactant "pairs" are
hydroxy/isocyanate
(blocked or unblocked), hydroxy/epoxy, carbamate/aminoplast,
carbamate/aldehyde,
acid/epoxy, amine/cyclic carbonate, amine/isocyanate (blocked or unblocked), .
urea/aminoplast, and the like.
[0094] Thus, in one embodiment, functional groups (F2) of nonvolatile solvent
(b'"~) may be any of the functional groups discussed above with respect to
functional
group (F1) of nonvolatile solvent (b",,). However, it will be appreciated that
functional
groups (F2) may not be the same as functional groups (F1). That is,
nonvolatile solvent
(b"~) will undergo reaction with at least one reactant (e) to produce
nonvolatile solvent
(b'"~). The reaction of nonvolatile solvent (bn~) with at least one reactant
(e) produces
nonvolatile solvent (b'"~) comprising at least two functional groups (F2).
[0095] In one exemplary embodiment, functional groups (F2) of nonvolatile
solvent (b'"~) will be at least one of carbamate (especially primary
carbamate),
hydroxyl, isocyanate, carbonate, beta-hydroxy urethane, mixtures thereof, and
the like.
In another exemplary embodiment, functional groups (FZ) of nonvolatile solvent
(b'n~)
will be either primary carbamate or hydroxyl. In one especially exemplary
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WO 2005/123787 PCT/US2005/020611
embodiment, functional groups (FZ) of nonvolatile solvent (b'"~) will be
primary
carbamate.
[0096] Illustrative reactants (e) are any reactants that may be used to
convert
functional groups (F1) of nonvolatile solvent (b"~) to functional groups (F2)
of
nonvolatile solvent (b'"~). Illustrative reactions and reactants (e) are
generally
discussed above with respect to the formation of preferred reactive components
(c). It
will be appreciated that the identity of the at least one reactant (e) will be
dependent
upon the identity of functional group (Fl) and the desired functional groups
(F2).
Multiple reactants (e) may be used either simultaneously or sequentially.
[0097] Hydroxyl functional groups (F2) or intermediate hydroxyl functional
groups may be obtained by the ring opening of an epoxy functional group (Fl)
with an
acid functional reactant (e). When only one epoxy functional group (Fl) is
present,
acid functional reactant (e) must have an additional functional group such as
hydroxy,
carbamate, urea, amide, and the like.
[0098] For example, carbamate functional groups (FZ) may be obtained via the
reaction of hydroxy functional groups (F1) with a reactant (e) selected from
low
molecular weight carbamate functional monomers such as methyl carbamate.
Alternatively, carbamate functional groups (F2) may be made by decomposing a
reactant (e) such as urea in the presence of hydroxyl functional groups (Fl).
Finally, in
another embodiment, carbamate functional groups (F2) may be obtained by
reacting a
first reactant (e) such as phosgene with a hydroxyl functional group (Fl)
followed by
reaction with another reactant (e) such as ammonia.
[0099] Amine functional groups (FZ) may be obtained via reduction of a nitrite
via reaction with a reactant (e) such as hydrogen gas.
[00100] Isocyanate functional groups (FZ) may be obtained via reaction of an
amine functional group (Fl) with a reactant (e) such as phosgene or carbon
dioxide,
with phosgene being preferred.
[0100] Aminoplast functional groups (F2) may be obtained via the reaction of
an activated amine functional group (Fl) and a reactant (e) that is an
aldehyde such as
formaldehyde. Illustrative activated amine groups are melamine,
benzoguanamine,
amides, carbamates, and the like. Alternatively, aminoplast functional groups
(F2)
may be made via reaction of carbamate functional groups (Fl) with a reactant
(e) that
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is an aldehyde. In another embodiment, the resulting aminoplast functional
group may
be etherified via reaction with another reactant (e) such as a monofunctional
alcohol.
[0101] Aldehyde functional groups (F2) may be made via reduction of an acid
functional group (FI) via reaction with at least one reactant (e) such as
hydrogen.
[0102] Urea functional groups (F2) may be made via reaction of an amine
functional group (F1) with a reactant (e) such as urea. Alternatively, urea
functional
groups (FZ) can be obtained via reaction of amine functional groups (F1) with
a
reactant (e) such as phosgene followed by additional reaction with another
reactant (e)
such as ammonia.
[0103] Epoxy functional groups (F2) may be made via reaction of acid
functional groups (F1) with a reactant (e) such as peroxide. Alternatively,
epoxy
functional groups (F2) will be obtained via the reaction of acid or hydroxyl
functional
groups (F1) with a reactant (e) such as epichlorohydrin.
[0104] Cyclic carbonate functional groups (F2) may be made via reaction of
an epoxy functional group (F1) with a reactant (e) such as carbon dioxide.
[0105] It will be appreciated that iiz some cases, the reaction of a reactant
(e)
with a nonvolatile solvent (b"~) having ouy one functional group (Fl) will
produce a
nonvolatile solvent (b'n~) having two or more functional groups (F2). For
example, the
reaction of an epoxy functional group (Fl) with a hydroxy acid reactant (e)
results in a
diol, wlule the reaction of a cyclic carbonate (Fl) with ammonia (reactant
(e)) results
in a hydroxy carbamate (beta or higher). Finally, the reaction of a cyclic
anhydride
with a hydroxy acid results in a di-acid.
[0106] It will thus be appreciated that in one exemplary embodiment, reactant
(e) may be at least one of low molecular weight carbamate functional reactants
(such
as simple alkyl carbamates), urea, phosgene, ammonia, carbon dioxide, acids,
aldehydes, alcohols, peroxides, epichlorohydrin, mixtures thereof, and the
like. In
another exemplary embodiment, when functional group (Fl) is hydroxyl, (e) may
be
an alkyl carbamate, urea, or phosgene and ammonia. In one especially exemplary
embodiment, reactant (e) will be an alkyl carbamate when functional group (Fl)
is
3 0 hydroxyl.
[0107] The reaction conditions suitable for the reaction of functional groups
(Fl) with at least one reactant (e) will generally be known to those of skill
in the art.
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[0108] As discussed above, the polymerization of reactant mixture (a) into
polymer (a') may occur either before, after, or simultaneously with the
reaction of
functional groups (F1) of the nonvolatile solvent (b"~) with the least one
reactant (e) to
provide nonvolatile solvent (b'",,) having at least two functional groups
(FZ). In one
exemplary embodiment, the two reactions will occur simultaneously. However, it
is
also possible for either of the two reactions to occur first, so long as both
reactions
occur at some point prior to the obtainment of mixture (II).
[0109] In one exemplary embodiment, the reactant mixture (a) will be
polymerized either before or simultaneously with the conversion of nonvolatile
solvent (b"~) to nonvolatile solvent (b'"~). In this case, some or all of any
functional
groups present on polymer (a') may undergo conversion simultaneously. For
example, in one exemplary embodiment, the conversion of hydroxyl functional
monomers (a) to carbamate functional monomers (a) may occur simultaneously
with
polymerization of monomers (a) and the conversion of hydroxy functional groups
(F1)
to carbamate functional groups (FZ).
[0110] Coating compositions of the invention will also comprise at least one
crosslinking agent (f). Crosslinking agent (f) will comprise at least one
functional
group (fi) that is reactive with functional groups (F2) of nonvolatile solvent
(b'",,).
Crosslinking agent (f) may further comprise additional functional groups (fii)
that are
reactive with any functional groups of polymer (a'). The disclosed coating
compositions may comprise one or more crosslinking agents (f), wherein
functional
groups (fi) and (fii) are on the same or different crosslinking agents (f). In
one
exemplary embodiment, a disclosed coating composition will comprise at least
one
crosslinking agent (f) having both functional groups (fi) and (fii).
[0111] Illustrative examples of crosslinlcing agents (f) are those
crosslinking
agents having one or more crosslinkable functional groups. Such functional
groups
include, for example, aminoplast, hydroxy, isocyanate, amine, epoxy, acrylate,
vinyl,
silane, and acetoacetate groups. These groups may be masked or blocked in such
a
way so that they are unblocked and available for the cross-linking reaction
under the
desired curing conditions, generally elevated temperatures. Useful
crosslinkable
functional groups include hydroxy, epoxy, acid, anhydride, silane, activated
methylene
and acetoacetate groups. Preferred crosslinking agents will have crosslinkable
functional groups that include hydroxy functional groups and amino functional
groups
27
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WO 2005/123787 PCT/US2005/020611
and isocyanate groups. Di- and/or polyisocyanates and/or aminoplast resins are
most
preferred for use as crosslinking agents in coating compositions comprising
the
mixture (II) of the invention. Mixed crosslinkers may also be used.
[0112] For example, when the nonvolatile solvent (b'n~) comprises hydroxy
functional groups (F2), for example, the reactant (e) may be an aminoplast
resin, a
polyisocyanate, a blocked polyisocyanate resin (including an isocyanurate,
biuret, or
the reaction product of a diisocyanate and a polyol having less than twenty
carbon
atoms), or an acid or anhydride functional crosslinking agent.
[0113] . In one exemplary embodiment, the crosslinker (f) will have functional
groups (fi), that will react with the functional groups (F2) to form a
crosslink that is
non-reversible under cure conditions. This will help to insure that the
reactive additive
remains crosslinked in the film. Some non-limiting examples of crosslinkable
functional groups pairs that fall under this category are:
carbamate:aminoplast,
hydroxy:epoxy, acid:epoxy, vinyl:vinyl, and hydroxy:isocyanate. An example of
a
crosslink that is reversible under cure conditions is hydroxy:aminoplast, and
hydroxy:activated methylene.
[0114] The coating compositions of the invention are particularly suitable for
use in automotive coating compositions, especially primers, basecoats, and/or
clearcoats, with clearcoats being especially preferred. The coating
compositions of the
invention may be powder coatings, waterborne, power slurry, or solventborne.
[0115] Coating compositions of the present invention preferably form the
outermost layer or layer of coating on a coated substrate. Preferably, the
instant
coating compositions are applied over one or more layers of primer coatings.
For
example, the coating compositions of the invention may be used as an
automotive
topcoat coating applied over a layer of electrocoat primer and/or primer
surfacer.
(0116] When such coating compositions are used as topcoat coatings, they
preferably have a 20 degree gloss, as defined by ASTM D523-89, of at least 80
or a
DOI, as defined by ASTM E430-91, of at least 80, or both. Such gloss and DOI
are
particularly useful in providing an automotive finish that will appeal to the
buyer of
the vehicle. Topcoat coatings may be one coat pigmented coatings or may be a
color-
plus-clear composite coating.
[0117] Coating compositions of the present invention, if used as a one coat
pigmented coating or the color coating of a color-plus-clear composite
coating, will
28
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WO 2005/123787 PCT/US2005/020611
include one or more pigments well-known in the art, such as inorganic pigments
like
titanium dioxide, carbon black, and iron oxide pigments, or organic pigments
like azo
reds, quinacridones, perylenes, copper phthalocyanines, carbazole violet,
monoarylide
and diarylide yellows, naphthol orange, and the like.
[0118] In a preferred embodiment, the coating composition of the present
invention is the clearcoat of a color-plus-clear composite coating. The
clearcoat may
be applied over a color coat according to the invention or may be applied over
a color
coat of a formulation already known in the art. Pigmented color coat or
basecoat
compositions for such composite coatings are well known in the art and do not
require
explanation in detail herein. Polymers known in the art to be useful in
basecoat
compositions include acrylics, vinyls, polyurethanes, polycaxbonates,
polyesters,
alkyds, and polysiloxanes. Such basecoats may comprise the polymer (a') of the
invention. Preferred polymers include acrylics and polyurethanes.
[0119] Other materials well-known to the coatings artisan, for example,
surfactants, fillers, stabilizers, wetting agents, dispersing agents, adhesion
promoters,
W absorbers, light stabilizers such as _H_AT.S, antioxidants, solvents,
catalysts, and/or
rheology control agents, may also be incorporated into the coating
compositions of the
invention. The amount of these materials used must be controlled to achieve
the
desired performance properties and/or to avoid adversely affecting the coating
characteristics.
[0120] Coating compositions can be coated onto an article by any of a number
of techniques well known in the art. These include, for example, spray
coating, dip
coating, roll coating, cut~tain coating, and the like. For automotive body
panels, spray
coating is preferred. When the coatings will be relatively thick, they are
usually
applied in two or more coats separated by a time sufficient to allow some of
the water
and/or solvent evaporate from the applied coating layer ("flash"). The coats
as applied
are usually from 1 to 3 mils of the coating composition, and a sufficient
number of
coats are applied to yield the desired final coating thickness.
[0121] Where a color-plus-clear composite coating is applied to the prepared
substrate, the color coat is usually applied in one or two coats, then allowed
to flash,
and the clear coat is then applied to the uncured color coat in one or two
coats. The
two coating layers are then cured simultaneously. Preferably, the cured base
coat
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layer is 0.5 to 1.5 mils thick and the cured clear coat layer is 1 to 3 mils,
more
preferably 1.6 to 2.2 mils thick.
[0122] Coating compositions of the invention are preferably subjected to
conditions so as to cure the coating layers. Although various methods of
curing may
be used, thermal-curing is preferred. Generally, thermal curing is effected by
exposing the coated article to elevated temperatures provided primarily by
radiative
heat sources. Curing temperatures will vary depending on the particular
blocking
groups used in the crosslinking agents, however they generally range between
93
degree C and 177 degree C. In a preferred embodiment, the cure temperature is
between 135 degree C and 165 degree C. In another preferred embodiment, a
blocked
acid catalyst is included in the composition and the cure temperature is
between 115
degree C and 140 degree C. In a different preferred embodiment, an unblocked
acid
catalyst is included in the composition and the cure temperature is between 80
degree
C and 100 degree C. The curing time will vary depending on the particular
components used and physical parameters, such as the thiclcness of the layers.
Typical
curing times range from 15 to 60 minutes, and preferably 15-25 minutes at the
target
temperature.
EXAMPLES
Example 1
Part lA
Polymerization using a reactive material (c) as a solvent and co-
tranesterification of
the reactive material and the acrylic polymer
[0123] A mixture of 650 parts of saturated a C36 fatty dimer diol and 350
parts of xylene was heated to 140°C under an inert atmosphere. Then a
mixture of
417 parts of hydroxyethyl methacrylate, 253 parts of styrene, 342 parts of 2-
ethylhexyl
methacrylate and 110 parts of t-butyl peroctoate was added over three and a
half
hours. The reaction mixture was then reduced to 110°C and a mixture of
30 parts of
toluene and 10 parts of t-butyl peroctoate was added over 30 minutes. The
reaction
was then held at 110°C for one hour.
[0124] To this reaction mixture was added 814 parts of toluene, 552.8 parts of
methyl carbamate, 3.2 parts of dibutyl tin oxide, and 6.9 parts of triisodecyl
phosphite.
The reaction mixture was brought to reflex under an inert atmosphere. Once at
reflex,
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the inert atmosphere was turned off. Methanol that was formed was removed from
the
reaction mixture with additional toluene added to keep the reflux temperature
below
120°C. After more than 95% of the hydroxy groups on both the acrylic
resin and
saturated C36 fatty diol were converted to primary carbamate groups, the
excess
methyl carbamate and toluene transcarbamation solvent was removed by vacuum
distillation. Then 715 parts of methyl propyl ketone was added. The final
resin had a
NV of 73.5%.
Part 1B
[0126] A coating composition was prepared by combining the materials in
order as set for below in Table 1 and mixing under agitation.
Table 1
Ingredient
Mixture from Part95.83
lA
Melaminel 18.04
Rhelogy Control 20.24
Agent'
LTVA' 3.16
HALS'' 1.50
PBA' 0.67
Blocked Acid Catalyst4.80
DB Acetate' 2.00
Methyl Propyl 10.58
I~etone
TOTAL 156.82
Example 2
Comparative Example
Part 2A
Preparation of a carbamate fiuictional acrylic resin
1 Resimene 747 Melamine from UCB
2 Solution of 10% Fumed Silica in Carbamate functional acrylic
3 Tinuvin 384B from Ciba-Geigy
4 Tinuvin 123
5 Lindron 22 from Lindros
6 Nacure 5225 from Ding Ind.
' From Eastman
31
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[0127] 817.4 parts of xylene was heated under an inert atmosphere to reflex.
The inert atmosphere was then turned off and a mixture of 659.5 parts of 2-
hydroxyethyl methacrylate, 394.7 parts of styrene, 533.5 parts of-ethylhexyl
methacrylate and 172 parts of t-butyl-2-ethylhexyl peroxide was added over a
three
hour period, followed by the addition of 20 parts of xylene. After holding for
30
minutes, the reaction mixture was cooled to 110°C under an inert
atmosphere. Then a
mixture of 15.6 parts of t-butyl-2-ethylhexyl peroxide and 46.8 parts of
toluene was
added over 30 minutes. Then 49 parts of toluene was added. The reaction
mixture
was then held at 110°C for an additional hour. The reactor was then set
up with a
paced column and an extractor to remove methanol, and a mixture of 3.1 parts
of
dibutyl tin oxide, 487.5 parts of methyl carbamate, 6.9 parts of triisodecyl
phosphite
and 636.6 parts of toluene was added. The system was allowed to come to
reflex.
The transcarbamation was taken to its stall point where ~95% of the hydroxy
groups
were converted into carbamate groups. The solvent and excess methylcarbamate
were
then removed by vacuum distillation. Then 500 grams of the vacuum stripped
resin
was dissolved into 214 grams of methyl propyl ketone. The final resin had a NV
of
70%.
Part 2B
Preparation of a carbamate functional C36 dimer
[0127] To a reactor set up with a packed column and an extractor to remove
methanol was added 662.4 parts of methyl carbamate, 2241 parts of Pripol 2030
(Uniqema), 872 parts of toluene, 4.2 parts of dibutyl tin oxide and 20.2 parts
of
triisodecyl phosphite. The reaction mixture was heated under an inert
atmosphere to
reflex. The inert atmosphere was then turned off and the reaction allowed to
continue
at reflex until ~99% of the hydroxy groups were converted to carbamate groups.
The
solvent and excess methyl carbamate was then removed by vacuum distillation to
form a colorless liquid that turned into a wax at room temperature.
Part 2C
[0128] A coating composition was prepared by combining the materials in
order as set for below in Table 2 and mixing under agitation.
Table 2
Ingredient
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Acrylic Resin from 57.60
Part 2A
C36 dicarbamate from 30.73
Part 2B
Melamine 17.41
Rhelogy Control Agents20.24
3.16
HALS11 1.50
PBAI' 0.67
Blocked Acid Catalysts'4.80
DB Acetates'' 2.00
Methyl Propyl Ketone 17.11
TOTAL 155.23
Example 3
Evaluation of Paint Samples
[0129] The curable coating compositions from Examples 1 and 2 were
evaluated per the following. The control was E126CG2023, a 1-component acrylic-
blocked isocyanate system available from BASF Core. of Southfield, MI. It can
be
seen that the composition of Example 1 shows improvements iiz scratch & mar
and
hardness. It also exhibits a higher cured film Tg and crossliiik density with
all other
properties essentially maintained.
Test on ro p
Wt Non-volatiles 51.2 65.04 65.71
Nanoscratch
Fracture Load 8.42 13.03 14.18
Plastic Deformation 0.49 0.32 0.27
140 QCT Humidity
~
Initial 3 1.5 2
Recovery 2 1.5 1
8 Resimene 747 Melamine from UCB
9 Solution of 10% Fumed Silica in Carbamate functional acrylic
'o Tinuvin 384B from Ciba-Geigy
11 Tinuvin 123
12 Lindron 22 from Lindros
13 Nacure 5225 from King Ind.
la From Eastman
33
Table 3
C t I Exam le 1 Example 2
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WO 2005/123787 PCT/US2005/020611
Repair Gravelometer
20 @ 275 5
50 @ 305 5 5 6
Tukon Hardness 9.8 10.4 9.3
Scratch & Mar
Crockmeter 81.55% 96.46% 95.73%
DMTA
Tg 84.54 134.02 117.04
Crosslink Density 404 1185 588
34
