U.S. patent application number 11/384183 was filed with the patent office on 2007-09-20 for emulsion polymer blend coating compositions and methods for increasing chalky substrate adhesion.
Invention is credited to Yakov Freidzon, Luz Clarena Shavel, Robert Sheerin, Yong Yang.
Application Number | 20070219307 11/384183 |
Document ID | / |
Family ID | 38518778 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070219307 |
Kind Code |
A1 |
Yang; Yong ; et al. |
September 20, 2007 |
Emulsion polymer blend coating compositions and methods for
increasing chalky substrate adhesion
Abstract
The present invention relates to a coating composition
containing a polymer blend dispersion including: a first polymer
having a relatively low molecular weight and a relatively low glass
transition temperature and comprising a self-crosslinking monomer;
and a second polymer having a relatively high molecular weight and
a relatively high glass transition temperature. Latex paint
compositions and architectural coatings containing the coating
composition according to the invention are also described herein,
as well as substrates coated therewith.
Inventors: |
Yang; Yong; (Hillsborough,
NJ) ; Freidzon; Yakov; (Bridgewater, NJ) ;
Sheerin; Robert; (North Caldwell, NJ) ; Shavel; Luz
Clarena; (Budd Lake, NJ) |
Correspondence
Address: |
THE H.T. THAN LAW GROUP
WATERFRONT CENTER SUITE 560
1010 WISCONSIN AVENUE NW
WASHINGTON
DC
20007
US
|
Family ID: |
38518778 |
Appl. No.: |
11/384183 |
Filed: |
March 17, 2006 |
Current U.S.
Class: |
524/522 ;
524/523 |
Current CPC
Class: |
C09D 133/08 20130101;
C09D 133/14 20130101; C08L 2312/08 20130101; C09D 143/04 20130101;
C08L 33/14 20130101; C08L 33/08 20130101; C08L 43/04 20130101; C08L
2312/00 20130101; C09D 133/08 20130101; C09D 133/14 20130101; C09D
143/04 20130101; C08L 2666/04 20130101; C08L 2666/04 20130101; C08L
2666/04 20130101 |
Class at
Publication: |
524/522 ;
524/523 |
International
Class: |
C08L 33/00 20060101
C08L033/00 |
Claims
1. A latex composition comprising a polymer blend of a first
polymer and a second polymer, wherein: the first polymer is made
from first constituent monomers, has a number average molecular
weight less than about 100,000 Daltons, has a glass transition
temperature calculated according to the Fox equation from about
-20.degree. C. to about 60.degree. C., and comprises a
self-crosslinking monomer; the second polymer is made from second
constituent monomers, has a number average molecular weight greater
than about 100,000 Daltons, and has a glass transition temperature,
calculated according to the Fox equation, from about -20.degree. C.
to about 60.degree. C.; the glass transition temperature of the
second polymer is at least 10.degree. C. higher than the glass
transition temperature of the first polymer; and the relative
proportion of the first polymer to the second polymer is from about
1:4 to 4:3 by weight.
2. The latex composition of claim 1, wherein the self-crosslinking
monomer comprises an acetoacetoxyalkyl acrylate, an
acetoacetoxyalkyl alkacrylate, a dialkoxyalkyl vinyl silane, a
trialkoxy vinyl silane, or a combination thereof.
3. The latex composition of claim 2, wherein the amount of the
self-crosslinking monomer is from about 0.1% to about 5% by weight
of the constituent monomers of the first polymer, and wherein the
self-crosslinking monomer is a trialkoxy vinyl silane.
4. The latex composition of claim 1, wherein the relative
proportion of first polymer to second polymer is from about 1:3 to
about 5:4 by weight.
5. The latex composition of claim 4, wherein the relative
proportion of first polymer to second polymer is from about 3:7 to
about 1:1 by weight
6. The latex composition of claim 1, wherein the glass transition
temperature of the first polymer is from about -5.degree. C. to
about 20.degree. C., and wherein the glass transition temperature
of the second polymer is from about 5.degree. C. to about
25.degree. C.
7. The latex composition of claim 1, wherein the number average
molecular weight of the first polymer is from about 7,000 Daltons
to about 80,000 Daltons
8. The latex composition of claim 1, wherein the number average
molecular weight of the first polymer is from about 15,000 Daltons
to about 60,000 Daltons.
9. The latex composition of claim 1, wherein the number average
molecular weight of the second polymer is from about 100,000
Daltons to about 1,500,000 Daltons.
10. The latex composition of claim 1, wherein the number average
molecular weight of the second polymer is from about 200,000 to
about 1,000,000.
11. The latex composition of claim 1, wherein the constituent
monomers of the first polymer are substantially acrylic or the
constituent monomers of the second polymer are substantially
acrylic.
12. The latex composition of claim 1, wherein the constituent
monomers of both the first polymer and the second polymer are
substantially acrylic.
13. The latex composition of claim 1, wherein the polymer blend is
substantially free from sequentially polymerized polymers.
14. A coating composition comprising the latex composition of claim
1.
15. A paint composition comprising the latex composition of claim
13.
16. The paint composition of claim 15, having a volatile organic
compound content less than about 100 g/L.
17. A coated substrate comprising a substrate having at least one
surface on which a coating of the paint composition of claim 15 is
disposed.
18. The coated substrate of claim 17, wherein the coating exhibits
less than about 25% peeling from the crosshatch adhesion test under
ASTM D3359 Method B.
19. The coated substrate of claim 17, wherein the substrate
comprises wood, a metal, a ceramic, a transparent substrate, a
translucent substrate, a polymer, a woven fabric, a non-woven
fabric, a building material, a chalky substrate, or a combination
thereof.
20. The coated substrate of claim 17, wherein the constituent
monomers of the first polymer of the polymer blend in the paint
composition are substantially acrylic, the constituent monomers of
the second polymer of the polymer blend in the paint composition
are substantially acrylic, or both.
21. A latex composition comprising a polymer blend of a first
polymer and a second polymer, wherein: the first polymer is made
from first constituent monomers, has a number average molecular
weight less than about 100,000 Daltons, has a glass transition
temperature, calculated according to the Fox equation, from about
-20.degree. C to about 60.degree. C., and comprises a
self-crosslinking monomer; the second polymer is made from second
constituent monomers, has a number average molecular weight greater
than about 100,000 Daltons, and has a glass transition temperature,
calculated according to the Fox equation, from about -20.degree. C.
to about 60.degree. C.; the glass transition temperature of the
second polymer is at least 10.degree. C. higher than the glass
transition temperature of the first polymer; the polymer blend is
substantially free from sequentially polymerized polymers; and the
first constituent monomers, the second constituent monomers, or
both, are substantially free from phosphorus-containing pendant
groups, from polyacid-containing pendant groups, or from both.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a coating composition
containing a polymer blend dispersion including a first polymer
having a relatively low molecular weight and a relatively low glass
transition temperature, and a second polymer having a relatively
high molecular weight and a relatively high glass transition
temperature. The emulsion coating composition according to the
invention can advantageously be used in paint compositions and
architectural coating applications.
BACKGROUND OF THE INVENTION
[0002] Good adhesion properties, particularly to chalky substrates,
are important to coatings such as paints and architectural
coatings. One conventional method for improving the chalk adhesion
properties of a coating composition is to add an alkyd resin to the
conventional coating composition. However, alkyd resins produce
premature yellowing, rendering the coatings undesirable in certain
circumstances.
[0003] Another method for improving the chalk adhesion properties
is to synthesize a polymer blend in a sequential polymerization.
Examples of acrylic-based polymer blends made by sequential
polymerization processes can be found in U.S. Pat. Nos. 5,990,228
and 6,710,112 B1.
[0004] The '228 patent discloses aqueous coating compositions
containing at least two polymer components which supposedly provide
adhesion and improved durability, as measured in dried coatings
made from the aqueous compositions by improved gloss retention or
dirt pickup resistance. Specifically, in Comparative Example 1 of
the '228 patent, this patent discloses the use of a pre-polymerized
latex core of 60 nm particulate poly(butyl acrylate-co-methyl
methacrylate-co-methacrylic acid), upon which was further
polymerized two layers of poly(butyl acrylate-co-methyl
methacrylate-co-acrylic acid) of the same composition. The at least
two polymer components are synthesized as core-shell polymers by a
sequential polymerization process.
[0005] The '112 patent discloses aqueous polymer dispersions having
two polymer phases that have different glass transition
temperatures but that are formed by a sequential polymerization
process. In addition, the molecular weights of the two polymer
phases are different, due to the addition at some point during the
sequential polymerization of a chain transfer reagent.
[0006] Other publications disclose alternatives to alkyd resin
modification in coating compositions.
[0007] For example, U.S. Patent Application Publication No.
2004/0161542 A1 and U.S. Pat. No. 6,630,533 both disclose
compositions containing at least one fatty acid ester. In the '542
publication, the fatty acid ester is unsaturated. In the '533
patent, the fatty acid ester comprises a C.sub.12 to C.sub.40
alkyl(meth)acrylate.
[0008] U.S. Pat. No. 5,376,704 discloses aqueous coating
compositions containing a neutralized half-ester product of an
acrylic polymer containing at least two reactive anhydride groups
that is crosslinked with an epoxy crosslinker. The molecular
weights of both these components are less than 100,000 Daltons.
[0009] U.S. Patent Application Publication No. 2004/0010091 A1
discloses two component coating compositions that cure under
ambient conditions. The coating composition of the '091 publication
contains crosslinkable and crosslinking components, with both
components having molecular weights under 100,000 Daltons.
[0010] U.S. Patent Application Publication No. 2004/0010071 A1
discloses an aqueous polymer blend composition containing soft and
hard polymer particles. The hard polymer particles have a glass
transition temperature greater than 25.degree. C., while the soft
polymer particles have a glass transition temperature less than or
equal to 25.degree. C. In addition, the hard polymer particles
constitute from 2-30 wt % of the composition, while the soft
polymer particles constitute from 70-98 wt % of the
composition.
[0011] U.S. Patent Application Publication No. 2005/0009954 A1
discloses aqueous polymer compositions containing hard polymers and
soft polymers, with at least the hard polymers include
phosphorus-containing and/or polyacid-containing pendant groups.
The hard polymers have a glass transition temperature of at least
20.degree. C., while the soft polymers have a glass transition
temperature of from -20.degree. C. to 5.degree. C. In addition, the
hard polymers constitute from 2-40 wt % of the composition, while
the soft polymer particles constitute from 60-98 wt % of the
composition.
[0012] There remains a need for other varied alternatives to alkyd
resins and sequentially polymerized polymer blends for improving
adhesion.
BRIEF SUMMARY OF THE INVENTION
[0013] The present invention involves a latex composition
comprising a polymer blend of a first polymer and a second polymer,
wherein: (a) the first polymer is made from first constituent
monomers, has a number average molecular weight less than about
100,000 Daltons, has a glass transition temperature from about
-20.degree. C. to about 60.degree. C., and comprises an amount of a
self-crosslinking monomer; (b) the second polymer is made from
second constituent monomers, has a number average molecular weight
greater than about 150,000 Daltons, and has a glass transition
temperature from about -20.degree. C. to about 60.degree. C.; (c)
the glass transition temperature of the second polymer is at least
10.degree. C. higher than the glass transition temperature of the
first polymer; and (d) the relative proportion of the first polymer
to the second polymer is from about 1:4 to 4:3 by weight.
[0014] The present invention also describes coating compositions
containing the latex composition according to the invention, as
well as coatings made therefrom and coated substrates on which the
coating compositions containing the latex composition according to
the invention are disposed.
DETAILED DESCRIPTION OF THE INVENTION
[0015] One aspect of the present invention relates to a latex
emulsion composition containing a polymer blend of: (i) a first
polymer having a relatively low molecular weight and a relatively
low glass transition temperature; and (ii) a second polymer having
a relatively high molecular weight and a relatively high glass
transition temperature. Advantageously, the first polymer is
polymerized from constituent monomers that include a
self-crosslinking monomer.
[0016] As used herein, the phrase "relatively low molecular weight"
means a number average molecular weight of less than about 100,000
Daltons. Also as used herein, the phrase "relatively high molecular
weight" means a number average molecular weight of greater than
about 100,000 Daltons, preferably greater than about 200,000
Daltons.
[0017] One of the benefits of relatively low molecular weight
chains in coating compositions containing the latex polymer blends
according to the invention can be improved substrate adhesion,
whereas one of the benefits of relatively high molecular weight
chains in the latex polymer blends according to the invention can
be increased physical/mechanical strength. Combining these benefits
by creating a coating composition containing a polymer blend having
both relatively high molecular weight and relatively low molecular
weight polymer chains is therefore desirable.
[0018] When conventional paint compositions containing relatively
high molecular weight acrylic-based latexes are applied to chalky
substrates, for example, they can tend to exhibit poor adhesion to
the chalky surface. In some cases, alkyd resins are combined with
these poorly-adhering acrylic-based latex-containing paint
compositions to improve the wet and/or dry adhesion properties.
Alkyd resins, however, may negatively affect certain qualities of
the paint compositions, including, but not limited to, causing loss
of gloss, causing yellowing, causing color fading, causing
chalkiness, causing brittleness, hindering clean-up, decreasing
emulsion stability (thus increasing the need for added surfactant),
increasing sensitivity to water, and the like, and combinations
thereof.
[0019] Another method for improving adhesion of paint compositions
applied on chalky substrates and for reducing or eliminating the
need for incorporating alkyd resins with relatively high molecular
weight acrylic-based latexes includes the formation of polymers
containing multimodal molecular weight distributions. Multimodal
molecular weight distributions in polymer blends are typically
attained by sequentially polymerizing monomers and by using a
molecular weight control agent, such as a chain transfer agent, at
some point during the polymerization process. See, e.g.,
commonly-owned, co-pending U.S. patent application Ser. No.
11/323,621, filed Dec. 30, 2005, and entitled "Emulsion Polymers
Having Multimodal Molecular Weight Distributions". Such sequential
polymerization processes have been described as forming core-shell
type polymers, such as those disclosed in U.S. Pat. Nos. 5,990,228
and 6,710,112 B1, for example. However, because of the nature of
the sequential polymerization process, the different molecular
weights are typically attained for identical polymers (i.e.,
containing the same constituent monomer feeds), or for polymers
that have relatively similar constituent monomer feeds.
[0020] It is believed that the use of polymer blend compositions
according to the invention containing both low molecular weight and
high molecular weight chains in paint compositions applied on
chalky substrates can advantageously reduce or eliminate the need
for incorporating alkyd resins with high molecular weight latex
polymers, and can be an alternative to sequentially polymerized
and/or core-shell type polymers with multimodal molecular weight
distributions. Without being bound by theory, it is believed that
the presence of the first polymer in the blend having the lower
molecular weight can sufficiently improve the adhesion of paint
compositions containing them to chalky substrates. Nevertheless,
because uniformly lower molecular weight polymer particles can tend
to compromise the physical and mechanical properties of the paint
compositions and/or the surfaces of the chalky substrates coated
therewith, it is also believed that a combination of low and high
molecular weight polymers can simultaneously result in acceptable
adhesion and acceptable physical/mechanical properties.
[0021] In one embodiment, the number average molecular weight of
the first polymer is less than about 100,000 Daltons and the number
average molecular weight of the second polymer is greater than
about 100,000 Daltons. For example, for the first polymer the
number average molecular weight can be from about 7,000 Daltons to
about 80,000 Daltons, preferably from about 15,000 Daltons to about
60,000 Daltons. The number average molecular weight of the second
polymer can be from about 100,000 Daltons to about 1,500,000
Daltons, preferably from about 200,000 Daltons to about 1,000,000
Daltons.
[0022] The glass transition temperatures of both polymers in the
blend are typically above about -30.degree. C. In a preferred
embodiment, the T.sub.g values of both polymers in the blend can
fall within the range from about -20.degree. C. to about 60.degree.
C., preferably from about -15.degree. C. to about 50.degree. C. In
one embodiment, the T.sub.g of the first polymer can be less than
about 25.degree. C. In a preferred embodiment, the T.sub.g of the
first polymer can be from about -15.degree. C. to about 40.degree.
C., preferably from about -10.degree. C. to about 30.degree. C.,
for example from about -5.degree. C. to about 20.degree. C. or from
about 0.degree. C. to about 10.degree. C. In another embodiment,
the T.sub.g of the second polymer can be less than about 25.degree.
C. In another preferred embodiment, the T.sub.g of the second
polymer can be from about -10.degree. C. to about 45.degree. C.,
preferably from about -5.degree. C. to about 35.degree. C., for
example from about 0.degree. C. to about 25.degree. C. or from
about 5.degree. C. to about 25.degree. C. In another preferred
embodiment, the T.sub.g of the second polymer can be at least about
0.degree. C. or at least about 80.degree. C., preferably from
10.degree. C. to 60.degree. C. and more preferably from 20.degree.
C. to 40.degree. C. Alternatively, the T.sub.g of the second
polymer is about 10.degree. C. to about 15.degree. C. greater than
the T.sub.g of the first polymer.
[0023] In one embodiment, the T.sub.g values for each of the
polymers of the blend can preferably be measured using conventional
tools and techniques known to those of skill in the art, e.g.,
differential scanning calorimetry (DSC), dynamic mechanical thermal
analysis (DMTA), or the like, or a combination thereof. In another
embodiment, the T.sub.g values for each of the polymers of the
blend can be completely calculated by applying Fox's law to known
T.sub.g values, e.g., from any edition of the Polymer Handbook such
as the 3.sup.rd ed. (1989), of the homopolymers corresponding to
each of the monomers used and their respective weight ratios. For
descriptions of this latter method, see, e.g., U.S. Pat. No.
6,723,779 and/or International Publication No. WO 94/04581, the
disclosures of both of which are incorporated herein by reference
in their entireties.
[0024] In a preferred embodiment, the relative proportion of the
first polymer to the second polymer in the polymer blend according
to the invention can be from about 1:4 to 2:1 by weight, for
example from about 1:4 to 4:3 by weight, preferably from about 1:3
to about 5:4 by weight, more preferably from about 1:3 to about 6:5
by weight, most preferably from about 3:7 to about 1:1 by
weight.
[0025] In the polymer blend of the present invention, both polymers
can be made from a mixture of constituent monomers containing (a)
diluent monomers having either no functional groups or functional
groups that are relatively unreactive and (b) functional (also
called crosslinkable) monomers having functional groups that are
relatively reactive and that are capable of crosslinking the
polymer with a crosslinking agent. The functional monomers can be
useful for later coalescence, and optionally crosslinking, if
desired, of one or both of the polymers in the blend. As a common
functional group is a carboxylic acid group, the content of the
functional monomers that are not also self-crosslinking herein can
be described as acid monomer content.
[0026] In one embodiment, the first polymer in the polymer blend
can have a self-crosslinking monomer content from about 0.1% to
about 5% by weight, preferably from about 0.2% to about 4% by
weight, for example from about 0.4% to about 3% by weight, from
about 0.2% to about 1.5% by weight, from about 0.5% to about 4% by
weight, or from about 0.5% to about 2% by weight.
[0027] In one embodiment, both of the polymers in the polymer blend
can have an average acid monomer content of less than about 10% by
weight, preferably less than about 7%, more preferably from about
0.1% to about 5%, for example from about 0.5% to about 3%. Although
the acid content is. described herein in terms of weight percent of
acid monomer, acid content can be quantified in many ways, e.g.,
acid number.
[0028] Another group of monomers also contain reactive functional
groups, but those groups are capable of crosslinking the polymer
without the presence of a crosslinking agent in the composition;
such monomers are collectively termed "crosslinking monomers"
herein and include, but are not limited to, "self-crosslinking"
monomers, which require no external crosslinking agent to form
crosslinks, "oxidatively crosslinking" monomers, which utilize
atmospheric oxygen but need no crosslinking agent in their
composition to form oxidative crosslinks, and the like.
[0029] Many different functional groups may be suitable as pendant
groups on the constituent monomers forming the polymers in the
blend according to the invention. Although the polymers in the
blend according to the invention can be described in terms of their
acid content, it should be understood that the term "acid content"
should include not merely the content of carboxylic acid-containing
monomers, but the combined content of any functional/crosslinkable
(but not crosslinking) monomers. Further, as used herein, the terms
"polymer" and "polymers" are used to refer to oligomers,
homopolymers, random copolymers, statistical copolymers,
alternating copolymers, periodic copolymer, bipolymers,
terpolymers, quaterpolymers, other forms of copolymers, adducts
thereof, substituted derivatives thereof, and combinations or
blends thereof. Such polymers can be linear, branched,
hyper-branched, crosslinked, block, di-block, multi-block, graft,
isotactic, syndiotactic, stereoregular, atactic, gradient,
multi-arm star, comb, dendritic, and/or any combination
thereof.
[0030] Examples of polymer repeat units having functional groups
can include, but are not limited to, acrylic acid, ionic acrylate
salts, alkacrylic acids, ionic alkacrylate salts, haloacrylic
acids, ionic haloacrylate salts, acetoacetoxyalkyl acrylates,
acetoacetoxyalkyl alkacrylates, polymerizable anhydrides such as
maleic anhydride, acrylamide, alkacrylamides, monoalkyl
acrylamides, monoalkyl alkacrylamides, alkacrylamidoalkyl
ethyleneureas such as those sold under the tradename Sipomer.TM.
WAM, alkenyloxyamidoalkyl ethyleneureas such as those sold under
the tradename Sipomer.TM. WAM, vinyl dicarboxylic organic acids
(e.g., itaconic acid, glutaconic acid, maleic acid, angelic acid,
fumaric acid, tiglic acid, and the like), monoalkyl esters of vinyl
dicarboxylic organic acids (e.g., methyl maleate, ethyl fumarate,
and the like), monoisopropenyl esters of saturated, vinyl
dicarboxylic organic acids, monoalkoxydialkyl vinyl silanes,
dialkoxyalkyl vinyl silanes, trialkoxy vinyl silanes, and the like,
and copolymers and combinations thereof.
[0031] As used herein, the prefix "alk" before an ethylenically
unsaturated monomer should be understood to indicate a
C.sub.1-C.sub.6 hydrocarbon side group attached to either carbon of
the olefinic pendant group, though it usually refers to a group
attached to the same carbon as the olefinic pendant group. For
example, the most basic alkacrylic acid is methacrylic acid.
However, if the "alk" group is on the vinyl carbon not containing
the pendant carboxylic acid, then a methacrylic acid becomes
crotonic acid, which is contemplated as an alkacrylic acid, as
defined herein. Another example includes tiglic acid (i.e.,
2-butene-2-carboxylic acid), which is an alkacrylic acid containing
two "alk" groups, with one methyl group attached to each vinyl
carbon. As used herein, the term "alkyl" should be understood to
mean an aliphatic C.sub.1-C.sub.18 hydrocarbon moiety. For
instance, the monomer ethyl methacrylate has a methyl group
attached as an ester to the pendant carboxylate group and an ethyl
group attached to the same carbon of the vinyl moiety as the
pendant carboxylate (i.e.,
CH.sub.2.dbd.C(CH.sub.2CH.sub.3)--C(.dbd.O)O(CH.sub.3)). As used
herein, the term "alkenyl" should be understood to mean a
C.sub.2-C.sub.18 hydrocarbon moiety having a single double bond,
preferably a terminal double bond. As used herein, the term
"alkoxy" group should be understood to mean a group having a
C.sub.1-C.sub.12 hydrocarbon or oxyhydrocarbon (i.e., containing
hydrogen, carbon, and oxygen atoms) moiety attached to a terminal
oxygen atom.
[0032] In the embodiments where the polymer repeat units include
ionic salts, their counterions can include, but are not limited to,
sodium, potassium, lithium, copper, silver, ammonium, tetraalkyl
ammonium, alkyl pyridinium ions such as N-methyl pyridinium,
tetraalkyl phosphonium ions, tetraaryl phosphonium ions, aralkyl
phosphonium ions such as methyltriphenylphosphonium and
methyltriphenoxyphosphonium, trialkylsulfonium ions such as
trimethylsulfonium, aralkyl sulfonium ions, trialkylsulfoxonium
ions such as trimethylsulfoxonium, aralkyl sulfoxonium ions, and
the like, and combinations thereof. As used herein, the term "aryl"
should be understood to mean an aromatic C.sub.6-C.sub.18 moiety,
and the term "aralkyl" should be understood to mean a moiety that
is partially aryl and partially alkyl.
[0033] In one embodiment, the constituent monomers of the first
polymer, the constituent monomers of the second polymer, or both,
can be substantially free from hydroxy-functional pendant groups
such as, but not limited to, those in hydroxyalkyl acrylates,
hydroxyalkyl alkacrylates, vinyl phenols, hydroxyalkyl vinyl
benzenes, only partially esterified acrylate esters of alkylene
glycols, only partially esterified acrylate esters of non-polymeric
polyhydroxy compounds like glycerol, only partially esterified
acrylate esters of polymeric polyhydroxy compounds, and the like.
In another embodiment, the constituent monomers of the first
polymer, the constituent monomers of the second polymer, or both,
can be substantially free from conjugated diene monomers such as,
but not limited to, butadienes, hexadienes, hexatrienes,
octadienes, octatrienes, octatetrenes, as well as hydrocarbon
analogs thereof, substituted halo- and/or cyano- derivatives
thereof, and the like, and a combination thereof. In another
embodiment, the constituent monomers of the first polymer, the
constituent monomers of the second polymer, or both, can be
substantially free from phosphorus-containing pendant groups, from
polyacid-containing pendant groups, or both. As used herein, the
terms "substantially no" and "substantially free from", referring
to a component in a composition, mean that the composition
comprises not more than about 1 wt %, preferably not more than
about 0.5 wt %, more preferably not more than about 0.1 wt %, most
preferably not more than about 0.02 wt %, or in some cases
completely none (about 0%), of the component.
[0034] In addition to the monomers containing functional groups,
both the polymers in the blend according to the invention can also
comprise diluent monomers or repeat units that contain pendant
groups that do not typically react with crosslinking agents.
Examples of such diluent monomers can include, but are not limited
to, alkyl acrylates, alkyl alkacrylates, alkyl esters of vinyl
monocarboxylic organic acids other than acrylates and alkacrylates
(e.g., ethyl tiglate, methyl crotonate, and the like), dialkyl
esters of vinyl dicarboxylic acids, styrene, alkylstyrenes (e.g.,
.alpha.-ethylstyrene, .alpha.-methylstyrene, vinyl toluene,
2,4-dimethylstyrene, 4-t-butylstyrene, and the like), halostyrenes
(e.g., .alpha.-bromostyrene, 2,6-dichlorostyrene, and the like),
isopropenyl esters of saturated, monocarboxylic organic acids
(e.g., isopropenyl acetate, isopropenyl isobutyrate, and the like),
monoisopropenyl monoalkyl esters of saturated, dicarboxylic organic
acids (e.g., isopropenyl alkyl oxalate, isopropenyl alkyl
succinate, and the like), vinyl carboxylate alkyl ethers (e.g.,
vinyl acetate, vinyl propionate, vinyl butyrates, vinyl benzoates,
halo-substituted versions thereof such as vinyl chloroacetate, and
the like), vinyl alkyl ethers, acrylonitrile, alkacrylonitriles,
dialkyl acrylamides, dialkyl alkacrylamides, allyl compounds (e.g.,
allyl chloride, allyl esters of saturated, monocarboxylic acids,
allyl alkyl esters of saturated, dicarboxylic organic acids, and
the like), and the like, and combinations thereof. Preferred
diluent monomers include, but are not limited to, C.sub.1-C.sub.8
alkyl acrylates, C.sub.1-C.sub.8 alkyl C.sub.1-C.sub.2
alkacrylates, styrene, C.sub.1-C.sub.4 alkylstyrenes, vinyl
acetate, and combinations thereof.
[0035] In one preferred embodiment, both the polymers in the blend
according to the invention can be substantially acrylic. As used
herein, the term "acrylic" refers to (co)polymer compositions made
from monomers selected from the group consisting of alkyl
acrylates, alkyl alkacrylates, acrylic acid, ionic acrylate salts,
alkacrylic acids, ionic alkacrylate salts, acrylamide,
alkacrylamides, monoalkyl acrylamides, monoalkyl alkacrylamides,
acrylonitrile, alkacrylonitriles, substituted versions thereof
(e.g., hydroxyalkyl acrylates, hydroxyalkyl alkacrylates,
alkacrylamidoalkyl ethyleneureas, alkenyloxyamidoalkyl
ethyleneureas, and the like), and the like, and combinations
thereof. As used herein, the term "substantially," at least with
regard to a component in a composition, means that the composition
contains at least about 90% by weight of that component, preferably
at least about 95% by weight of that component, more preferably at
least about 97% by weight of that component, most preferably at
least about 99% by weight of that component, in some cases at least
about 99.9% by weight of that component, or completely comprises
(about 100% by weight of) that component.
[0036] Acrylic latex copolymers containing acrylonitriles are known
in the art to improve certain physical properties as compared to
non-acrylonitrile-containing acrylics, but can significantly
increase cost and can introduce undesirable environmental issues.
Thus, in one embodiment, the diluent monomers specifically exclude
acrylonitrile and alkacrylonitriles.
[0037] In a preferred embodiment, at least the second polymer
(i.e., having a relatively high molecular weight and a relatively
high T.sub.g) of the polymer blend is substantially free from
crosslinking monomers. In another preferred embodiment, the first
polymer of the polymer blend can contain an amount of a
self-crosslinking monomer but can be substantially free from
oxidatively crosslinking monomers. In one embodiment, the polymer
blend according to the invention can be used in architectural
coatings and in paint formulations. In another embodiment, the
polymer blend according to the invention can be combined with one
or more pigments/colorants in hydrophobic latex applications.
[0038] Each of the polymers in the polymer blends according to the
invention are typically polymerized in a latex system comprising
water, surfactant, the desired monomer(s), an initiator, a polymer
molecular weight control agent (in the case of the low molecular
weight polymer), optionally an organic solvent, optionally a pH
adjustor, optionally a chaser agent, optionally a coalescing agent,
and optionally a preservative, which can be added at various times.
The polymer blend according to the invention, in a preferred
embodiment, specifically excludes two polymers that are
sequentially polymerized; for instance, the polymer blend according
to the invention may advantageously contain substantially no
sequentially polymerized polymers.
[0039] Examples of surfactants useful in the compositions according
to the invention can include, but are not limited to, nonionic
and/or anionic surfactants such as ammonium nonoxynol-4 sulfate,
nonylphenol (10) ethoxylate, nonylphenol (.about.10mol %)
ethoxylate, nonylphenol (.about.40mol %) ethoxylate, octylphenol
(.about.40mol %) ethoxylate, octylphenol (9-10) ethoxylate, sodium
dodecyl sulfonate, sodium tetradecyl sulfonate, sodium hexadecyl
sulfonate, polyether phosphate esters, alcohol ethoxylate phosphate
esters, those compounds sold under the tradename Triton.TM. (e.g.,
QS series, CF series, X series, and the like), those compounds sold
under the tradename Rhodapon.TM., those sold under the tradename
Rhodapex.TM., those compounds sold under the tradename
Rhodacal.TM., those compounds sold under the tradename
Rhodafac.TM., and the like, and combinations thereof.
[0040] Examples of initiators and chaser solutions useful in the
compositions according to the invention can include, but are not
limited to, ammonium persulfate, sodium persulfate, redox systems
such as sodium hydroxymethanesulfinate (sodium formaldehyde
sulfoxylate; reducer) and t-butyl-hydroperoxide (oxidizer), and the
like, and combinations thereof, typically in an aqueous solution.
Either or both of these components can optionally contain an
additional surfactant and/or a pH adjustor, if desired to stabilize
the emulsion.
[0041] Examples of pH adjustors useful in the compositions
according to the invention can include, but are not limited to,
ammonium hydroxide, sodium hydroxide, sodium carbonate, sodium
bicarbonate, potassium hydroxide, potassium carbonate, potassium
bicarbonate, ammonia, and the like, and combinations thereof. In
certain cases, compounds that qualify as pH adjustors can be added
for purposes other than adjusting pH, e.g., emulsion stabilization,
and yet are still characterized herein as pH adjustors.
[0042] Polymer molecular weight control agents are designed to
control (usually to limit) the molecular weight of a propagating
polymer. While polymer molecular weight control agents can include
things like radiation, they are typically molecules added to the
polymerization mixture. Examples of polymer molecular weight
control agents include, but are not limited to, chain transfer
agents (CTAs), e.g., alkyl mercapto-esters such as isooctyl
mercaptopropionate, alkyl mercaptans, and the like, and
combinations thereof. Chain transfer agents typically operate as
polymer molecular weight control agent molecules, for example, by
catalytically or consumptively terminating a propagating polymer
chain in a way that also initiates a newly propagating polymer
chain. In this way, the amount of chain transfer agent(s) can be
tailored to reduce the target polymer molecular weight in a set
polymerization system, or alternately, in combination with
calculation of the amount of initiator, can be calculated to target
a particular average polymer molecular weight (e.g., within a given
range) of a polymerization system.
[0043] Examples of biocides/preservatives useful in the
compositions according to the invention can include, but are not
limited to, hydroxy-functional aza-dioxabicyclo compounds such as
those commercially available from ISP under the tradename
Nuosept.TM. 95, those compounds sold under the tradename SKANE.TM.,
isothiazolones such as those sold under the tradename Kathon.TM.,
Polyphase.TM. additives from Troy Corp. and the like, and
combinations thereof.
[0044] In another aspect of the invention, the latex polymer blend
compositions can be included in a paint or other coating
composition, which can advantageously be an emulsion further
containing water, a coalescence solvent, a pH adjustor, a
surfactant, a defoamer, a pigment, optionally but preferably a
dispersant, optionally but preferably a rheology modifier, and
optionally but preferably a biocide or preservative.
[0045] Examples of coalescence solvents and organic solvents useful
in the compositions according to the invention can include, but are
not limited to, 2-ethylhexyl ether of ethylene glycol (e.g.,
commercially available as Eastman.TM. EEH solvent), methyl
carbitol, propylene glycol, ethylene glycol, those compounds sold
under the tradename TEXANOL.TM., plasticizers such as dibutyl
phthalate, and the like, and combinations thereof.
[0046] Examples of defoamers useful in the compositions according
to the invention can include, but are not limited to,
polysiloxane-polyether copolymers such as those sold by Tego under
the tradename Foamex.TM., those sold under the tradename BYK.TM.,
those sold under the tradename Drewplus.TM., those sold under the
tradename Surfynol.TM., and the like, and combinations thereof.
[0047] Examples of anticorrosive agents useful in the compositions
according to the invention can include, but are not limited to,
sodium nitrite and the like.
[0048] Examples of dispersants useful in the compositions according
to the invention can include, but are not limited to,
2-amino-2-methyl- 1 -propanol, hydrophobic copolymers such as
Tamol.TM. 165A, carboxylated polyelectrolyte salts such as
Tamol.TM. 173A, and the like, and combinations thereof.
[0049] Examples of rheology modifiers useful in the compositions
according to the invention can include, but are not limited to,
those commercially available from Rohm & Haas under the
tradename Acrysol.TM., such as RM-8W, RM-825, RM-5000, RM-2020 NPR
and RM-825, Natrasol.TM. and Aquaflow.TM. from Aqualon Division of
Hercules Inc. and UCAR Polyphobe.TM. from Dow.
[0050] While typically multiple pigments/colorants are present in
end-use latexes that are to be used in paint or architectural
coating applications, sometimes only a white pigment, such as a
zinc oxide and/or a titanium oxide, is added in the early stages of
the formation of the paint composition (e.g., in the base
composition). In such a case, any other desired pigments/colorants
of various colors (including more white pigment) can optionally be
added at the later stages of, or after, formation of the paint
composition. Examples of pigments/colorants useful according to the
invention can include, but are not limited to, carbon black, iron
oxide black, iron oxide yellow, iron oxide red, iron oxide brown,
organic red pigments, including quinacridone red and metallized and
non-metallized azo reds (e.g., lithols, lithol rubine, toluidine
red, naphthol red), phthalocyanine blue, phthalocyanine green,
mono- or di- arylide yellow, benzimidazolone yellow, heterocyclic
yellow, DAN orange, quinacridone magenta, quinacridone violet, and
the like, and any combination thereof. These exemplary color
pigments can be added as powders, but can more conveniently be
added as aqueous dispersions to paint compositions according to the
invention.
[0051] Additionally or alternately, extender pigments/colorants can
be added, e.g., to the grind composition portion of the paint
composition. Examples of extender pigments/colorants useful in the
paint compositions according to the invention can include, but are
not limited to, silica, silicates, carbonates such as calcium
carbonates, and the like, and combinations thereof.
[0052] The coating compositions containing the blend of first and
second polymers according to the invention can exhibit a wide range
of viscosities, depending upon the application. In one embodiment,
the viscosity of the polymer blend latex composition can be from
about 65 to about 130 Krebunits (KU), preferably from about 70 to
about 110 KU, more preferably from about 75 to about 105 KU. While
coalescence, degradation, and other factors can cause the viscosity
to increase over time, it is preferable that the viscosity not
increase beyond about 130 KU, preferably not beyond about 120 KU,
more preferably not beyond about 115 KU, and in some cases not
beyond about 110 KU.
[0053] The polymer blends and/or latex coating compositions
according to the invention can advantageously exhibit a pH from
about 6 to about 10, although the pH needs only to be sufficient to
maintain the stability of the particular blend and/or latex
composition in combination with the surfactant(s) and other
stabilizing components.
[0054] In most applications, the polymer blends and/or latex
coating compositions according to the invention are typically
applied as a coating on a substrate. The substrate may or may not
depend upon the product in which acrylic latex according to the
invention is used. For example, when the acrylic latex is used in a
stain composition, the substrate can typically be wood or the like.
Examples of substrates can include, but are not limited to: wood,
including natural wood, compressed particulate wood, faux or
artificial wood, wood composites, and the like, and combinations
thereof; metals, including metal alloys, metal composites, coated
metals, metallic surfaces, and the like, and combinations thereof;
ceramics, including metal oxides, metal nitrides, metal
oxynitrides, metal sulfides, metal carbides, and the like, and
combinations thereof; transparent and/or translucent substrates
such as glasses, polycarbonates, acrylics, styrenics, and the like,
and combinations thereof; polymers; woven and/or non-woven fabrics;
building materials such as dry wall, sheet rock, and the like, and
combinations thereof; chalky substrates; and the like; and
combinations thereof.
[0055] In one embodiment, a paint composition containing the
polymer blend composition according to the invention can be
formulated according to the following method. First, a pigment
dispersion composition, or grind, is formed by: combining an
organic solvent, water, a dispersant, a pH adjustor, a surfactant,
a defoamer, a colorant/pigment, and a biocide/preservative;
stirring and optionally grinding for a period of time to
sufficiently mix the ingredients; and, while continuing to stir
and/or grind, adding more water. To this pigment dispersion
composition can be added the first polymer and the second polymer
of the polymer blend according to the invention, followed by a pH
adjustor, if desired, and a performance additive composition
comprising an organic solvent, a surfactant, and a defoamer.
Optionally but preferably, an anticorrosive solution can then be
added. Then, a rheology modifier can be added, optionally including
more water, if desired, and also a pH adjustor, thus forming a
paint composition. Furthermore, if desired, more colorant(s) and/or
pigment(s) can be added to the paint composition either to
compliment the (white) pigment(s)/colorant(s) already in the
pigment dispersion composition or to add another desired color to
the paint composition. A coalescing agent may optionally be added
later.
EXAMPLES
[0056] The following Examples are merely illustrative of certain
embodiments of the invention and contain comparisons of
compositions and methods according to the invention with the prior
art and/or embodiments not according to the invention. The
following Examples are not meant to limit the scope and breadth of
the present invention, as recited in the appended claims.
Example 1
Low Molecular Weight, Low T.sub.g Polymer w/o Self-Crosslinking
Monomer
[0057] Example 1 describes a low molecular weight, low glass
transition temperature polymer formed without a self-crosslinking
monomer present in the constituent monomers. The number average
molecular weight of the polymer of Example 1 was found to be about
29,000 Daltons, and the glass transition temperature of the polymer
of Example 1 was found to be about -5.degree. C. The latex polymer
formulation, in order of addition, is described below in Table 1.
TABLE-US-00001 TABLE 1 Monomer Ingredients Amount (grams) content
Aqueous Surfactant Solution deionized water 845 RHODACAL DS-4
surfactant 1 Total Monomer Emulsion* deionized water 190 RHODACAL
DS-4 surfactant 40 RHODAPEX CO-436 surfactant 10 SIPOMER WAM-IV
monomer 25 3.8 wt % methacrylic acid monomer 12 1.8 wt % methyl
methacrylate monomer 460 0.6 wt % 2-ethylhexyl acrylate monomer 610
93.7 wt % isooctyl 2-mercaptopropionate CTA 5 First Initiator
Solution deionized water 20 ammonium persulfate 2.5 Second
Initiator Solution deionized water 40 ammonium persulfate 2.5
deionized water (rinse) 10 Chaser Solutions t-butyl hydroperoxide
1.4 deionized water 10 sodium formaldehyde sulfoxylate 1 deionized
water 15 pH Adjustor ammonium hydroxide (26% in H.sub.2O) 5
deionized water 10
[0058] The glass transition temperature value for the polymer of
Example 1 was calculated according to Fox's law. The molecular
weight value for the polymer of Example 1 was obtained by analyzing
the acrylic latex polymer particles using a GPC method using WATERS
410 with differential Refractomer and tetrahydrofuran as mobile
pahse at 40.degree. C.
Example 2
Low Molecular Weight, Low T.sub.g Polymer With Self-Crosslinking
Monomer
[0059] Example 2 describes a first polymer of the polymer blend
according to the invention, i.e., a low molecular weight, low glass
transition temperature polymer formed with about 0.9 wt % of a
self-crosslinking monomer present in the constituent monomers. The
molecular weight of the polymer of Example 2 was found to be about
34,000 Daltons (number average; weight average, about 95,000
Daltons; and polydispersity, about 2.8), and the glass transition
temperature of the polymer of Example 2 was calculated to be about
-5.degree. C. The latex polymer formulation, in order of addition,
is described below in Table 2. TABLE-US-00002 TABLE 2 Monomer
Ingredients Amount (grams) content Aqueous Surfactant Solution
deionized water 845 RHODACAL DS-4 surfactant 1 Total Monomer
Emulsion* deionized water 190 RHODACAL DS-4 surfactant 40 RHODAPEX
CO-436 surfactant 10 SIPOMER WAM QM1458 monomer 25 2.2 wt %
methacrylic acid monomer 12 1.1 wt % methyl methacrylate monomer
460 41.2 wt % 2-ethylhexyl acrylate monomer 610 54.6 wt % isooctyl
2-mercaptopropionate CTA 5 vinyltriethoxysilane monomer 10 0.9 wt %
First Initiator Solution deionized water 20 ammonium persulfate 2.5
Second Initiator Solution deionized water 40 ammonium persulfate
2.5 deionized water (rinse) 10 Chaser Solutions t-butyl
hydroperoxide 1.4 deionized water 10 sodium formaldehyde
sulfoxylate 1 deionized water 15 pH Adjustor ammonium hydroxide
(26% in H.sub.2O) 5 deionized water 10
[0060] The glass transition temperature value for the polymer of
Example 2 was calculated according to Fox's law. The molecular
weight value for the polymer of Example 2 was obtained by analyzing
the acrylic latex polymer particles using the same GPC method as in
Example 1.
Example 3
Low Molecular Weight, Low T.sub.g Polymer With Self-Crosslinking
Monomer
[0061] Example 3 describes a first polymer of the polymer blend
according to the invention, i.e., a low molecular weight, low glass
transition temperature polymer formed with about 1.8 wt % of a
self-crosslinking monomer present in the constituent monomers. The
number average molecular weight of the polymer of Example 3 was
found to be about 19,000 Daltons, and the glass transition
temperature of the polymer of Example 3 was calculated to be about
-5.degree. C. The latex polymer formulation, in order of addition,
is described below in Table 3. TABLE-US-00003 TABLE 3 Monomer
Ingredients Amount (grams) content Aqueous Surfactant Solution
deionized water 845 RHODACAL DS-4 surfactant 1 Total Monomer
Emulsion* deionized water 190 RHODACAL DS-4 surfactant 40 RHODAPEX
CO-436 surfactant 10 SIPOMER WAM QM1458 monomer 25 2.2 wt %
methacrylic acid monomer 12 1.1 wt % methyl methacrylate monomer
460 40.8 wt % 2-ethylhexyl acrylate monomer 610 54.1 wt % isooctyl
2-mercaptopropionate CTA 10 vinyltriethoxysilane monomer 20 1.8 wt
% First Initiator Solution deionized water 20 ammonium persulfate
2.5 Second Initiator Solution deionized water 40 ammonium
persulfate 2.5 deionized water (rinse) 10 Chaser Solutions t-butyl
hydroperoxide 1.4 deionized water 10 sodium formaldehyde
sulfoxylate 1 deionized water 15 pH Adjustor ammonium hydroxide
(26% in H.sub.2O) 5 deionized water 10
[0062] The glass transition temperature value for the polymer of
Example 3 was calculated according to Fox's law. The molecular
weight value for the polymer of Example 3 was obtained by analyzing
the acrylic latex polymer particles using the GPC method described
in Example 1.
Examples 4-6
Paint Compositions Containing High Molecular Weight, High T.sub.g
Polymers
[0063] Examples 4-6 describe paint compositions each comprising a
single, relatively high molecular weight, relatively high glass
transition temperature polymer. The paint composition formulations,
in order of addition, are described below in Table 4.
TABLE-US-00004 TABLE 4 Example 4 Example 5 Example 6 Ingredients
Amount (grams) Amount (grams) Amount (grams) Grind Composition
water 133 133 90 TAMOL 731A dispersant 15 15 15 Zinc oxide pigment
23 23 23 TRONOX CR-826 pigment 292 292 292 Kaolin pigment 50 50 --
Pigment(s)/colorant(s), if desired DREWPLUS L475 defoamer 0.7 0.7
0.7 TRITON X-100 surfactant 20 20 10 SKANE M-8 microbiocide 1.9 1.9
1.9 NUOSEPT 95 microbiocide 0.9 0.9 1 DREWPLUS L475 defoamer 0.5
0.5 0.5 RHOPLEX SG-10M* polymer 550 -- -- RHOPLEX MV-23.sup.#
polymer -- 550 -- RHOPLEX VSR-50.sup.x polymer -- -- 550 pH
Adjuster, if desired Performance Additive Composition TEXANOL
coalescent 20.8 14.8 -- OPTIFILM Enhancer400 coalescent -- -- 15
propylene glycol solvent 35 35 35 Anticorrosive Solution, if
desired pH Adjuster, if desired Rheology Modifier ACRYSOL RM-2020
NPR 20 20 20 ACRYSOL RM-825 7.2 14.6 1.7 water 34 34 30 Stability
Additive DREWPLUS L-475 defoamer 4 4 4 Other colorant(s), if
desired *RHOPLEX .TM. SG-10M is an acrylic emulsion polymer
commercially available from Rohm & Haas. .sup.#RHOPLEX .TM.
MV-23 is an acrylic emulsion polymer commercially available from
Rohm & Haas. .sup.xRHOPLEX .TM. VSR-50 is an acrylic emulsion
polymer commercially available from Rohm & Haas.
[0064] The polymers used in the paint compositions of Examples 4-6
were analyzed similarly to the polymers of Examples 1-3 and were
found to have number average molecular weights of greater than
100,000 Daltons and glass transition temperatures of 25.degree. C.,
6.degree. C. and 12.degree. C. based on commercial samples and
technical specifications. In addition, the paint compositions of
Examples 4-6 exhibited as-formulated viscosities of about 85 KU,
about 88 KU, and about 95 KU, respectively. Furthermore, the paint
composition of Example 6 has a VOC content of less than about 100
g/L.
Examples 7-9
Paint Compositions According to the Invention Containing a Polymer
Blend of a First, Low Molecular Weight, Low T.sub.g Polymer and a
Second, High Molecular Weight, High T.sub.g Polymer
[0065] Examples 7-9 describe paint compositions according to the
invention, each comprising a polymer blend of a first, relatively
low molecular weight, relatively low glass transition temperature
polymer and a second, relatively high molecular weight, relatively
high glass transition temperature polymer. The paint composition
formulations of all three Examples, in order of addition, are
described below in Table 5. TABLE-US-00005 TABLE 5 Example 7
Example 8 Example 9 Ingredients Amount (grams) Amount (grams)
Amount (grams) Grind Composition water 133 133 133 TAMOL 731A
dispersant 15 15 15 Zinc oxide pigment 23 23 23 TRONOX CR-826
pigment 292 292 292 Hydrous aluminum silicate pigment 50 50 --
Pigment(s)/colorant(s), if desired DREWPLUS L475 defoamer 0.7 0.7
0.7 TRITON X-100 surfactant 20 20 20 SKANE M-8 microbiocide 1.9 1.9
1.9 NUOSEPT 95 microbiocide 0.9 0.9 0.9 DREWPLUS L475 defoamer 0.5
0.5 0.5 RHOPLEX SG-10M* polymer 275 275 -- Polymer from Example 1
275 -- -- Polymer from Example 2 -- 275 275 RHOPLEX MV-23.sup.#
polymer -- -- 275 pH Adjuster, if desired Performance Additive
Composition TEXANOL coalescent 18.8 20.8 20.8 propylene glycol
solvent 35 35 35 Anticorrosive Solution, if desired pH Adjuster, if
desired Rheology Modifier ACRYSOL RM-2020 NPR 20 20 20 ACRYSOL
RM-825 10.1 9.0 10.2 water 34 34 34 Stability Additive DREWPLUS
L-475 defoamer 4 4 4 Other colorant(s), if desired *RHOPLEX .TM.
SG-10M is an acrylic emulsion polymer commercially available from
Rohm & Haas. .sup.#RHOPLEX .TM. MV-23 is an acrylic emulsion
polymer commercially available from Rohm & Haas.
[0066] The paint compositions of Examples 7-9 exhibited
as-formulated viscosities of about 85 KU, about 88 KU, and about 85
KU, respectively.
Examples 10-12
Paint Compositions According to the Invention Containing a Polymer
Blend of a First. Low Molecular Weight. Low T.sub.g Polymer and a
Second, High Molecular Weight, High T.sub.g Polymer
[0067] Examples 10-12 describe paint compositions according to the
invention, each comprising a polymer blend of a first, relatively
low molecular weight, relatively low glass transition temperature
polymer containing a self-crosslinking monomer and a second,
relatively high molecular weight, relatively high glass transition
temperature polymer. The paint composition formulations of all
three Examples, in order of addition, are described below in Table
6. TABLE-US-00006 TABLE 6 Example 10 Example 11 Example 12
Ingredients Amount (grams) Amount (grams) Amount (grams) Grind
Composition water 133 118 118 TAMOL 731A dispersant 15 15 15 Zinc
oxide pigment 23 23 23 TRONOX CR-826 pigment 292 292 292 Hydrous
aluminum silicate pigment 50 50 -- Pigment(s)/colorant(s), if
desired DREWPLUS L475 defoamer 0.7 0.7 0.7 TRITON X-100 surfactant
20 20 20 SKANE M-8 microbiocide 1.9 1.9 1.9 NUOSEPT 95 microbiocide
0.9 -- -- Kathon LX (1.5%) surfactant -- 1 1 DREWPLUS L475 defoamer
0.5 0.5 0.5 RHOPLEX .TM. VSR-50.sup.x polymer 275 -- -- Polymer
from Example 2 275 385 -- RHOPLEX SG-10M* polymer -- 165 225
Polymer from Example 3 -- -- 225 pH Adjuster, if desired
Performance Additive Composition OPTIFILM Enhancer400 coalescent 14
-- -- ARCHER RC coalescent -- 12 8 propylene glycol solvent 35 20
12 TEXANOL coalescent -- -- 3 butyl carbitol solvent -- -- 3
Anticorrosive Solution, if desired pH Adjuster, if desired Rheology
Modifier ACRYSOL RM-2020 NPR 20 25 25 ACRYSOL RM-825 9.2 7 9.7
water 34 49 49 Stability Additive DREWPLUS L-475 defoamer 4 5 5
Other colorant(s), if desired .sup.xRHOPLEX .TM. VSR-50 is an
acrylic emulsion polymer commercially available from Rohm &
Haas. *RHOPLEX .TM. SG-10M is an acrylic emulsion polymer
commercially available from Rohm & Haas.
[0068] The paint compositions of Examples 10-12 exhibited
as-formulated viscosities of about 86 KU, about 86 KU, and about 88
KU, respectively. In addition, the paint composition of Example 10
was a low-VOC composition (i.e., it exhibited a volatile organic
compound content of less than 50 g/L, or about 5% w/v), and the
paint compositions of Examples 11-12 both exhibited VOC content of
about 55 g/L (or about 5.5% w/v) to about 65 g/L (or about 6% w/v).
The VOC content was estimated from the formulation, based on EPA
Method 24 and the following formula: VOC content (g/L)=[weight of
VOCs (g)]/([total volume in liters]-[water volume in liters])
Viscosity Gloss, and VOC Content Values
[0069] Table 7 below shows the results of these characteristic
tests for the paint compositions of Examples 4-12. TABLE-US-00007
TABLE 7 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12
viscosity (KU) 85 88 95 85 88 85 86 86 88 ICI viscosity 1.2 1.4 1.4
1.2 1.2 1.2 1.1 1.2 1.3 (poise) Gloss (60.degree.) 36 39 60 35 36
42 38 44 36 VOC (g/L) 140 138 94 137 140 128 46 58 64
Chalk Adhesion Testing
[0070] Chalk binding tests are typically performed on chalky
substrates. Chalky substrates are commercial alkyd paints that have
been naturally weathered to achieve an ASTM chalk ratings of about
5. A suitable test method is described in U.S. Pat. No.
6,268,420.
[0071] In these cases, chalky substrates are western red cedar
panels painted with commercially available alkyd paints and
weathered to have ASTM ratings from 5 to 6 using the method
described in the '420 patent. Various 3-mil thick draw down
coatings of paint compositions were applied to these panels and let
dry for about 7 days at ambient conditions. After drying, wet and
dry adhesion of the paint coatings were evaluated using Scotch.TM.
600 tape and a 6.times.6 cross-hatch adhesion standard test, as
detailed in ASTM D3359 Method B. For wet adhesion, the coated
panels were placed in a fog box, simulating rain conditions at 100%
humidity, for about 4 hours and were dried in air at ambient
conditions for about 1 hour prior to the Crosshatch Adhesion test.
The percentage peeling (area) and an ASTM rating were tabulated for
coatings made from each of the paint compositions of Examples 4-12,
as well as Comparative Example A (a paint composition containing a
blend of an alkyd resin and a high molecular weight, high glass
transition temperature polymer, as described herein, which
composition is commercially available from Benjamin Moore, Inc., as
Benjamin Moore 0961B). Table 8 below shows those results.
TABLE-US-00008 TABLE 8 Chalk Adhesion Chalky Substrate ASTM Sample
(% peeling) Rating Example 4 100% 6 Example 5 50% 6 Example 6 40% 6
Example 7 10% 6 Example 8 15% 6 Example 9 10% 6 Example 10 10% 6
Example 11 5% 5 Example 12 0% 5 Comparative Ex. A 10% 5
[0072] The results in Table 8 show that the polymer blends
according to the invention (Examples 7-12) have at least comparable
chalk adhesion properties to an alkyd resin-containing polymer
blend (Comparative Example A) and that all the blends exhibited
superior chalk adhesion properties to the single polymer coating
compositions (Examples 4-6). Further, because the polymer blends of
Examples 7-12 contain substantially no alkyd resin, it is believed
that they all exhibit yellowing characteristics superior to those
of the alkyd resin-containing polymer blend of Comparative Example
A.
Resistance to Surfactant Leaching and Water Softening
[0073] Surfactant leaching is a test for probing the extent of
exterior water spotting on a coating. The test method for
surfactant leaching involved forming 3-mil draw down panels of each
coating composition. These panels were then allowed to dry in air
at ambient conditions for about 24 hours. Each panel was then held
so that the coating on the substrate was oriented vertically, at
which point 3-5 drops of water were applied over the coated area.
Without changing the orientation of the panels, the coatings were
allowed to dry. The presence or absence of visible staining on each
panel was noted and rated from 1 to 5, with 1 representing the most
visible stain, and with 5 representing no visible stain.
[0074] The exterior water sensitivity, or water softening, testing
method involved forming 3-mil draw down panels of each coating
composition. These panels were then allowed to dry in air at
ambient conditions for about 24 hours. Each panel was then held so
that the coating on the substrate was oriented horizontally, at
which point approximately 3 drops of water were applied over the
coated area and allowed to "soak" for about 2 minutes. The panels
were then carefully blotted dry and scratched with a fingernail to
test for any softening of the coatings, which were noted as ratings
from 1 to 5, with 1 representing the worst softening of the
coatings upon exposure to the water, and with 5 representing no
observable softening upon exposure to the water.
[0075] Table 9 below shows the results of both tests on coatings
made from the paint compositions of Examples 4-5 and 7-9. The
results indicate that the paint compositions containing polymer
blends according to the invention in which the first polymer
contains an amount of self-crosslinking monomer (Examples 8-9)
exhibited improved resistance to both surface leaching and water
softening. TABLE-US-00009 TABLE 9 Exam- Exam- Exam- Exam- Exam- ple
4 ple 5 ple 7 ple 8 ple 9 Surfact. Leach. 3 3 3 4 5 Rating Water
Resist. 3 3 3 4 4 Rating
Low Temperature Coalescence
[0076] Low temperature coalescence testing is designed to probe the
ability of a coating composition to form a uniform and smooth
coating on a substrate. The test method for low temperature
coalescence involved first cooling a number of 6''.times.6'' upson
panels to about 35.degree. F. for about 1 hour. Each panel is then
coated with draw downs of each composition having a thickness
starting at 8 mils and going to 28 mils. These panels were then
kept about 35.degree. F. in a refrigerator for about 24 hours, and
were allowed to recover for about 1 hour at room temperature. The
presence or absence of visible cracks on each panel was noted and
rated from 8 to 28+, based on the thinnest panel on which cracks
were first evident, with each number represent its mil-thickness,
and with 28+ representing that none of the panels showed
cracks.
[0077] Table 10 below shows the results of the low temperature
coalescence testing for coatings made from the paint compositions
of Examples 4, 6-8, 10, and 12. TABLE-US-00010 TABLE 10 Exam- Exam-
Exam- Exam- Exam- Exam- ple 4 ple 6 ple 7 ple 8 ple 10 ple 12 LTC
Rating 10 8 28+ 28+ 28+ 28+
[0078] While various embodiments of the present invention have been
described above, it should be understood that they have been
presented by way of illustration and example only, and not
limitation. It will be apparent to persons skilled in the relevant
art that various changes in form and detail can be made therein
without departing from the spirit and scope of the invention. Thus,
the breadth and scope of the present invention should not be
limited by any of the above-described exemplary embodiments, but
should be defined only in accordance with the appended claims and
their equivalents. It will also be understood that each feature of
each embodiment discussed herein, and of each reference cited
herein, can be used in combination with the features of any other
embodiment. All patents and publications discussed herein are
incorporated by reference herein in their entirety.
* * * * *