U.S. patent application number 10/515184 was filed with the patent office on 2006-03-09 for low-voc aqueous coating compositions with excellent freeze-thaw stability.
This patent application is currently assigned to BASF Corporation. Invention is credited to Terri A. Cunningham, Rolf Dersch, Joerg Leuninger, Konrad Roschmann, Cheng-Le Zhao, Li Zhuo.
Application Number | 20060052502 10/515184 |
Document ID | / |
Family ID | 29710088 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060052502 |
Kind Code |
A1 |
Zhao; Cheng-Le ; et
al. |
March 9, 2006 |
Low-voc aqueous coating compositions with excellent freeze-thaw
stability
Abstract
The present invention is an aqueous coating composition having
excellent freeze-thaw stability and a low-VOC content. The aqueous
coating composition of the invention includes at least one latex
polymer derived from at least one monomer and at least one
polymerizable alkoxylated surfactant, at least one pigment, and
water. In accordance with the invention, less than 3.0% by weight
of anti-freeze agents based on the total weight of the aqueous
coating composition are used in the composition. The present
invention also includes a method of preparing an aqueous coating
composition such as a latex paint including the above
components.
Inventors: |
Zhao; Cheng-Le; (Charlotte,
NC) ; Cunningham; Terri A.; (Concord, NC) ;
Zhuo; Li; (Fort Mill, SC) ; Roschmann; Konrad;
(Ludwigshafen-Edigheim, DE) ; Leuninger; Joerg;
(Mainz, DE) ; Dersch; Rolf; (Neustadt,
DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
BASF Corporation
3000 Continental Drive-North
mount Olive
NJ
07828
|
Family ID: |
29710088 |
Appl. No.: |
10/515184 |
Filed: |
May 13, 2003 |
PCT Filed: |
May 13, 2003 |
PCT NO: |
PCT/EP03/04975 |
371 Date: |
July 12, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10163953 |
Jun 6, 2002 |
6933415 |
|
|
10515184 |
Jul 12, 2005 |
|
|
|
Current U.S.
Class: |
524/425 ;
524/435; 524/445 |
Current CPC
Class: |
C09D 5/024 20130101;
C08K 5/42 20130101; C08K 5/49 20130101; C08K 5/04 20130101 |
Class at
Publication: |
524/425 ;
524/435; 524/445 |
International
Class: |
C08K 3/26 20060101
C08K003/26 |
Claims
1. A aqueous coating composition, comprising: (a) at least one
latex polymer derived from at least one monomer and at least one
polymerizable alkoxylated surfactant having the structure:
R.sup.1--R.sup.2 wherein R.sup.1 is an allyl group selected from
the group consisting of CH3-CH.dbd.CH-- and CH2=CH--CH2-, and R2 is
a radical comprising at least two carbon atoms and at least one
oxyethylene or oxypropylene unit; (b) at least one pigment; (c)
water; and (d) less than 3.0% by weight based on the total weight
of the aqueous coating composition of anti-freeze agents.
2. The composition according to claim 1, comprising less than 1.0%
by weight based on the total weight of the aqueous coating
composition of anti-freeze agents.
3. The composition according to claim 1, being substantially free
of anti-freeze agents.
4. The composition according to claim 1, wherein R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n---
R.sup.4; R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n--R.sup-
.4; preferably R.sup.4 is hydroxy or (--PO.sup.4M), n is from about
5 to about 100; and m is from 0 to about 100.
5. The composition according to claim 4, wherein R.sup.3 is
C.sub.7-C.sub.13 alkyl.
6. The composition according to claim 4, wherein R.sup.3 is
C.sub.9H.sub.19.
7. The composition according to claim 4, wherein n is from about 5
to about 40.
8. The composition according to claim 1, wherein the at least one
pigment includes at least one pigment selected from the group
consisting of TiO.sub.2, clay, CaCO.sub.3, aluminum oxide, silicon
dioxide, magnesium oxide, talc (magnesium silicate), barytes
(barium sulfate), zinc oxide, zinc sulfite, sodium oxide, potassium
oxide and mixtures thereof.
9. The composition according to claim 1, wherein the at least one
pigment includes TiO.sub.2, calcium carbonate or clay.
10. The composition according to claim 1, wherein the inorganic
pigment includes TiO.sub.2.
11. The composition according to claim 1, wherein the at least one
latex polymer is selected from the group consisting of pure
acrylics, styrene acrylics, vinyl acrylics and acrylated ethylene
vinyl acetate copolymers.
12. The composition according to claim 1, wherein the at least one
latex polymer includes a pure acrylic.
13. The composition according to claim 12, wherein the at least one
latex polymer is derived from at least one acrylic monomer selected
from the group consisting of acrylic acid, acrylic acid esters,
methacrylic acid, and methacrylic acid esters.
14. The composition according to claim 13, wherein the at least one
latex polymer is further derived from one or more monomers selected
from the group consisting of styrene, .alpha.-methyl styrene, vinyl
chloride, acrylonitrile, methacrylonitrile, ureido methacrylate,
vinyl acetate, vinyl esters of branched tertiary monocarboxylic
acids, itaconic acid, crotonic acid, maleic acid, fumaric acid,
ethylene, and C4-C8 conjugated dienes.
15. The composition according to claim 1, further comprising one or
more additives selected from the group consisting of dispersants,
surfactants, rheology modifiers, defoamers, thickeners, biocides,
mildewcides, colorants, waxes, perfumes and co-solvents.
16. A latex paint composition, comprising: (a) at least one latex
polymer derived from at least one monomer and at least one
polymerizable alkoxylated surfactant having the structure:
R.sup.1--R.sup.2 wherein R.sup.1 is an allyl group selected from
the group consisting of CH.sub.3--CH.dbd.CH-- and
CH.sub.2.dbd.CH--CH.sub.2--; R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n---
R.sup.4; R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m-13
(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4; preferably R.sup.4 is
hydroxy or (--PO.sup.4M), n is from about 5 to about 100; and m is
from 0 to about 100. (b) at least one latex polymer derived from at
least one acrylic monomer selected from the group consisting of
acrylic acid, acrylic acid esters, methacrylic acid, and
methacrylic acid esters; (c) at least one pigment; (d) water; and
(e) less than 3.0% by weight based on the total weight of the
aqueous coating composition of anti-freeze agents.
17. The paint composition according to claim 16, wherein R.sup.3 is
C.sub.7-C.sub.13 alkyl.
18. The paint composition according to claim 16, wherein the latex
polymer is a pure acrylic latex polymer.
19. The paint composition according to claim 18, wherein the latex
polymer is a butyl acrylate/methyl methacrylate copolymer.
20. A method of preparing a aqueous coating composition, comprising
the step of: mixing (1) at least one latex polymer derived from at
least one monomer and at least one polymerizable alkoxylated
surfactant having the structure: R.sup.1--R.sup.2 wherein R.sup.1
is an allyl group selected from the group consisting of
CH.sub.3--CH.dbd.CH-- and CH.sub.2.dbd.CH--CH.sub.2--, and R.sup.2
is a radical comprising at least two carbon atoms and at least one
oxyethylene or oxypropylene unit; and (2) at least one pigment;
wherein the aqueous coating composition includes less than 3.0% by
weight based on the total weight of the aqueous coating composition
of anti-freeze agents.
21. The method according to claim 20, wherein R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n---
R.sup.4; R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n--R.sup-
.4; preferably R.sup.4 is hydroxy or (--PO.sup.4M), n is from about
5 to about 100; and m is from 0 to about 100.
22. The method according to claim 21, wherein R.sup.3 is
C.sub.7-C.sub.13 alkyl.
23. The method according to claim 21, wherein R.sup.3 is
C.sub.9H.sub.19.
24. The method according to claim 21, wherein n is from about 5 to
about 40.
25. The method according to claim 20, wherein the pigment is at
least one pigment selected from the group consisting of TiO.sub.2,
clay, CaCO.sub.3, aluminum oxide, silicon dioxide, magnesium oxide,
talc (magnesium silicate), barytes (barium sulfate), zinc oxide,
zinc sulfite, sodium oxide, potassium oxide and mixtures
thereof.
26. The method according to claim 20, wherein the pigment includes
TiO.sub.2, calcium carbonate or clay.
27. The method according to claim 20, wherein the pigment includes
TiO.sub.2.
28. The method according to claim 20, wherein said mixing step
comprises mixing at least one latex polymer selected from the group
consisting of pure acrylics, styrene acrylics, vinyl acrylics and
acrylated ethylene vinyl acetate copolymers.
29. The method according to claim 20, wherein the at least one
latex polymer includes a pure acrylic.
30. The method according to claim 20, wherein the at least one
latex polymer is derived from at least one acrylic monomer selected
from the group consisting of acrylic acid, acrylic acid esters,
methacrylic acid, and methacrylic acid esters.
31. The method according to claim 30, wherein the at least one
latex polymer is further derived from one or more monomers selected
from the group consisting of styrene, .alpha.-methyl styrene, vinyl
chloride, acrylonitrile, methacrylonitrile, ureido methacrylate,
vinyl acetate, vinyl esters of branched tertiary monocarboxylic
acids, itaconic acid, crotonic acid, maleic acid, fumaric acid,
ethylene, and C4-C8 conjugated dienes.
32. The method according to claim 20, wherein said mixing step
comprises further mixing at least one additive selected from the
group consisting of dispersants, surfactants, rheology modifiers,
defoamers, thickeners, biocides, mildewcides, colorants, waxes,
perfumes and co-solvents.
33. The method according to claim 20, further comprising the step
of preparing the polymer latex binder using emulsion polymerization
by feeding the at least one monomer to a reactor in the presence of
at least one initiator and the at least one polymerizable
surfactant and polymerizing the monomers to produce the latex
binder, wherein said mixing step comprises mixing the at least one
pigment with the resulting latex binder to produce the aqueous
coating composition.
34. The method according to claim 33, wherein said step of
preparing the polymer latex binder comprises: preparing an
initiator solution comprising the initiator; preparing a monomer
pre-emulsion comprising the at least one monomer and the at least
one polymerizable surfactant; adding the initiator solution to a
reactor; and adding the monomer pre-emulsion to the reactor.
35. The method according to claim 33, wherein said preparing step
comprises feeding monomers to a reactor comprising at least one
acrylic monomer selected from the group consisting of acrylic acid,
acrylic acid esters, methacrylic acid, and methacrylic acid
esters.
36. The method according to claim 35, wherein said preparing step
comprises feeding monomers to a reactor further comprising one or
more monomers selected from the group consisting of styrene,
.alpha.-methyl styrene, vinyl chloride, acrylonitrile,
methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters
of branched tertiary monocarboxylic acids, itaconic acid, crotonic
acid, maleic acid, fumaric acid, ethylene, and C4-C8 conjugated
dienes.
37. In a method for reducing the VOC content of an aqueous coating
composition comprising a polymer latex, a pigment and water,
without substantially reducing the freeze-thaw stability of the
aqueous coating composition, the improvement comprising preparing
the latex polymer used in the aqueous coating composition from at
least one monomer and at least one polymerizable alkoxylated
surfactant, the at least one polymerizable alkoxylated surfactant
having the structure: R.sup.1--R.sup.2 wherein R.sup.1 is an allyl
group selected from the group consisting of CH.sub.3--CH.dbd.CH--
and CH.sub.2.dbd.CH--CH.sub.2--, and R.sup.2 is a radical
comprising at least two carbon atoms and at least one oxyethylene
or oxypropylene unit.
38. The method according to claim 37, wherein R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n---
R.sup.4R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n--R.sup-
.4; preferably R.sup.4 is hydroxy or (--PO.sup.4M), n is from about
5 to about 100; and m is from 0 to about 100.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the use of surfactants for
reducing the VOC content of aqueous coating compositions such as
paint and paper coating compositions while still maintaining the
freeze-thaw stability of these compositions. In particular, the
present invention relates to the use of certain polymerizable
alkoxylated surfactants in latex polymers to reduce the VOC content
of aqueous paint and paper coating compositions while maintaining
the freeze-thaw stability of these compositions.
BACKGROUND OF THE INVENTION
[0002] Latex paints are used for a variety of applications
including interior and exterior, and flat, semi-gloss and gloss
applications. In order to provide latex paints with good film
formation, coalescing agents are often added to these paints.
Exemplary coalescing agents include 2,2,4-trimethyl-1,3-pentanediol
monoisobutyrate (i.e. TEXANOL.RTM. commercially available from
Eastman Chemical) and 2-ethylhexyl benzoate (i.e. VELATE.RTM. 378
commercially available from Vesicol Corporation).
[0003] In addition to coalescing agents, latex paints include
anti-freeze agents to allow the paints to be used even after they
have been subjected to freezing conditions. In addition,
anti-freeze agents typically increase the open time for latex
paints. Exemplary anti-freeze agents include ethylene glycol,
diethylene glycol and propylene glycol. These anti-freeze agents
are discussed in detail in "Antifreezes", Ulmann's Encyclopedia of
Industrial Chemistry, 5.sup.th ed., vol. A3, pages 23-31.
[0004] The additives used as coalescing agents and anti-freeze
agents are effective for their purposes but are becoming more and
more undesirable because they are volatile organic compounds
(VOC's). After application of the latex paint to a substrate, the
VOC's slowly evaporate into the surroundings. As permissible VOC
levels continue to decrease as a result of increased environmental
regulations, there has become a need in the art to produce latex
paints with lower VOC levels. However, there is also a need to
maintain the performance of latex paints even at these lower VOC
levels.
SUMMARY OF THE INVENTION
[0005] It has been discovered that the use of certain polymerizable
alkoxylated surfactants in aqueous coating compositions reduces the
need to include anti-freeze agents in these compositions. In
accordance with the invention, aqueous coating compositions (e.g.
latex paints) including these polymerizable alkoxylated surfactants
can be produced having excellent freeze-thaw stabilities with the
addition of little or no anti-freeze agents. The aqueous coating
compositions of the invention include less than 3.0% by weight and
preferably less than 1.0% by weight of anti-freeze agents based on
the total weight of the aqueous coating composition. More
preferably, the aqueous coating compositions are substantially free
of anti-freeze agents. Therefore, aqueous coating compositions can
be produced in accordance with the invention that possess lower VOC
levels than conventional aqueous coating compositions and thus that
are more environmentally desirable.
[0006] The aqueous coating compositions of the invention include at
least one latex polymer derived from at least one monomer and at
least one polymerizable alkoxylated surfactant, at least one
pigment, and water. The polymerizable alkoxylated surfactant used
in the latex polymer has the structure: R.sup.1--R.sup.2 wherein
R.sup.1 is an allyl group selected from the group consisting of
CH.sub.3--CH.dbd.CH-- and CH.sub.2.dbd.CH--CH.sub.2--, and R.sup.2
is a radical comprising at least two carbon atoms and at least one
oxyethylene or oxypropylene unit. Preferably, R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3))n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)),.sub.m--(O--CH.sub.2--CH.sub.2).sub.n--
-R.sup.4; R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n--R.sup-
.4; preferably R.sup.4 is hydroxy or (--PO.sup.4M), n is from about
5 to about 100; and m is from 0 to about 100. More preferably,
R.sup.3 is C.sub.7-C.sub.13 alkyl (e.g. C.sub.9H.sub.19) and n is
from about 5 to about 40.
[0007] In a preferred embodiment of the invention, the at least one
pigment includes at least one pigment selected from the group
consisting of TiO.sub.2, CaCO.sub.3, clay, aluminum oxide, silicon
dioxide, magnesium oxide, sodium oxide, potassium oxide, talc,
barytes, zinc oxide, zinc sulfite and mixtures thereof. More
preferably, the at least one pigment includes TiO.sub.2, calcium
carbonate or clay. The at least one latex polymer in the aqueous
coating composition can be a pure acrylic, a styrene acrylic, a
vinyl acrylic or an acrylated ethylene vinyl acetate copolymer and
is more preferably a pure acrylic. The at least one latex polymer
is preferably derived from at least one acrylic monomer selected
from the group consisting of acrylic acid, acrylic acid esters,
methacrylic acid, and methacrylic acid esters. For example, the at
least one latex polymer can be a butyl acrylate/methyl methacrylate
copolymer or a 2-ethylhexyl acrylate/methyl methacrylate copolymer.
Typically, the at least one latex polymer is further derived from
one or more monomers selected from the group consisting of styrene,
.alpha.-methyl styrene, vinyl chloride, acrylonitrile,
methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters
of branched tertiary monocarboxylic acids, itaconic acid, crotonic
acid, maleic acid, fumaric acid, ethylene, and C4-C8 conjugated
dienes. In addition to the above components, the aqueous coating
composition can include one or more additives selected from the
group consisting of dispersants, surfactants, rheology modifiers,
defoamers, thickeners, biocides, mildewcides, colorants, waxes,
perfumes and co-solvents.
[0008] The present invention further includes a method of preparing
an aqueous coating composition, comprising the step of preparing
the polymer latex binder using emulsion polymerization by feeding
monomers to a reactor in the presence of at least one initiator and
the at least one polymerizable surfactant as described above and
polymerizing the monomers and the polymerizable surfactant to
produce the latex binder. The at least one pigment and other
additives can then be mixed with the resulting latex binder to
produce the aqueous coating composition. The step of preparing the
polymer latex binder can include preparing an initiator solution
comprising the initiator, preparing a monomer pre-emulsion
comprising monomers and the polymerizable alkoxylated surfactant of
the present invention, adding the initiator solution to a reactor,
and adding the monomer pre-emulsion to the reactor. The
incorporation of the polymerizable alkoxylated surfactants in the
polymer latex enables the coating composition to have a lower VOC
content while maintaining the freeze-thaw stability of the aqueous
coating composition at desirable levels.
[0009] These and other features and advantages of the present
invention will become more readily apparent to those skilled in the
art upon consideration of the following detailed description, which
describe both the preferred and alternative embodiments of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] In the following detailed description, preferred embodiments
are described in detail to enable practice of the invention.
Although the invention is described with reference to these
specific preferred embodiments, it will be understood that the
invention is not limited to these preferred embodiments. But to the
contrary, the invention includes numerous alternatives,
modifications and equivalents as will become apparent from
consideration of the following detailed description.
[0011] The present invention is an aqueous coating composition
having a low-VOC content but that has excellent freeze-thaw
stability comparable to conventional aqueous coating compositions.
The aqueous coating composition of the invention includes at least
one latex polymer derived from at least one monomer and at least
one polymerizable alkoxylated surfactant, at least one pigment and
water.
[0012] The at least one latex polymer used in the aqueous coating
composition is preferably derived from monomers comprising at least
one acrylic monomer selected from the group consisting of acrylic
acid, acrylic acid esters, methacrylic acid, and methacrylic acid
esters. In addition, the latex polymer can optionally include one
or more monomers selected from the group consisting of styrene,
.alpha.-methyl styrene, vinyl chloride, acrylonitrile,
methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl
esters_of branched tertiary monocarboxylic acids (e.g. vinyl esters
commercially available under the mark VEOVA.RTM. from Shell
Chemical Company or sold as EXXAR.RTM. Neo Vinyl Esters by
ExxonMobil Chemical Company), itaconic acid, crotonic acid, maleic
acid, fumaric acid, and ethylene. It is also possible to include
C4-C8 conjugated dienes such as 1,3-butadiene, isoprene and
chloroprene. Preferably, the monomers include one or more monomers
selected from the group consisting of n-butyl acrylate, methyl
methacrylate, styrene and 2-ethylhexyl acrylate. The latex polymer
is typically selected from the group consisting of pure acrylics
(comprising acrylic acid, methacrylic acid, an acrylate ester,
and/or a methacrylate ester as the main monomers); styrene acrylics
(comprising styrene and acrylic acid, methacrylic acid, an acrylate
ester, and/or a methacrylate ester as the main monomers); vinyl
acrylics (comprising vinyl acetate and acrylic acid, methacrylic
acid, an acrylate ester, and/or a methacrylate ester as the main
monomers); and acrylated ethylene vinyl acetate copolymers
(comprising ethylene, vinyl acetate and acrylic acid, methacrylic
acid, an acrylate ester, and/or a methacrylate ester as the main
monomers). The monomers can also include other main monomers such
as acrylamide and acrylonitrile, and one or more functional
monomers such as itaconic acid and ureido methacrylate, as would be
readily understood by those skilled in the art. In a particularly
preferred embodiment, the latex polymer is a pure acrylic such as a
butyl acrylate/methyl methacrylate copolymer or a ethylhexyl
acrylate/methyl methacrylate copolymer derived from monomers
including butyl acrylate, ethylhexyl acrylate and methyl
methacrylate. The latex polymer dispersion preferably includes from
about 30 to about 75% solids and a mean latex particle size of from
about 70 to about 650 nm. The latex polymer is preferably present
in the aqueous coating composition in an amount from about 5 to
about 60 percent by weight, and more preferably from about 8 to
about 40 percent by weight (i.e. the weight percentage of the dry
latex polymer based on the total weight of the coating
composition).
[0013] The at least one polymerizable alkoxylated surfactant used
to form the polymer latex has the structure: R.sup.1--R.sup.2
wherein R.sup.1 is an allyl group selected from the group
consisting of CH.sub.3--CH.dbd.CH-- and
CH.sub.2.dbd.CH--CH.sub.2--, and R.sup.2 is a radical comprising at
least two carbon atoms and at least one oxyethylene or oxypropylene
unit. R.sup.2 is
--C.sub.6H.sub.3(R.sup.3)--(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--O--CH.sub.2--CH(CH.sub.2--O--C.sub.6H.sub.4--R.sup.3)--(O--CH.sub.2--CH-
.sub.2).sub.n--R.sup.4, --(O--CH.sub.2--CH.sub.2).sub.n--R.sup.4,
--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4,
--(O--CH.sub.2--CH.sub.2).sub.m--(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup-
.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n---
R.sup.4; R.sup.3 is an alkyl group; R.sup.4 is hydroxy or a polar
group such as sulfonate (--SO.sub.3M), sulfate (--SO.sub.4M),
phosphonate (--PO.sub.3M) or phosphate (--PO.sub.4M); M is H.sup.+,
Na.sup.+, NH.sub.4.sup.+, K.sup.+ or Li.sup.+ with the provision
that R.sup.4 cannot be (--SO.sup.4M) or (--PO.sub.4M) if R.sup.2 is
(O--CH.sub.2--CH(CH.sub.3)).sub.n--R.sup.4 or
--(O--CH.sub.2--CH(CH.sub.3)).sub.m--(O--CH.sub.2--CH.sub.2).sub.n--R.sup-
.4; preferably R.sup.4 is hydroxy or (--PO.sup.4M), n is from about
5 to about 100; and m is from 0 to about 100. More preferably,
R.sup.3 is C.sub.7-C.sub.13 alkyl (e.g. C.sub.9H.sub.19) and n is
from about 5 to about 40. The term "alkyl" as used herein includes
linear and branched alkyl groups. Suitable surfactants for use in
the invention include surfactants sold under the marks NOIGEN.RTM.
RN and HITENOL.RTM. BC and are commercially available from
Montello, Inc or the PLURIOL.RTM. A . . . R(E) grades from BASF AG.
For example, NOIGEN.RTM. RN-10, HITENOL.RTM. BC-10, HITENOL.RTM.
BC-20 and PLURIOL.RTM. A10 R can be used in the invention. The
surfactant is typically present in the aqueous polymer dispersion
in an amount from greater than 0 to about 5% by weight based on
polymer weight, more preferably from about 0.5 to about 3% by
weight based on polymer weight.
[0014] As mentioned above, the aqueous coating composition includes
at least one pigment. The term "pigment" as used herein includes
non-film-forming solids such as pigments, extenders, and fillers.
The at least one pigment is preferably selected from the group
consisting of TiO.sub.2 (in both anastase and rutile forms), clay
(aluminum silicate), CaCO.sub.3 (in both ground and precipitated
forms), aluminum oxide, silicon dioxide, magnesium oxide, talc
(magnesium silicate), barytes (barium sulfate), zinc oxide, zinc
sulfite, sodium oxide, potassium oxide and mixtures thereof.
Suitable mixtures include blends of metal oxides such as those sold
under the marks MINEX.RTM. (oxides of silicon, aluminum, sodium and
potassium commercially available from Unimin Specialty Minerals),
CELITES.RTM. (aluminum oxide and silicon dioxide commercially
available from Celite Company), ATOMITES.RTM.) (commercially
available from English China Clay International), and
ATTAGELS.RTM.) (commercially available from Engelhard). More
preferably, the at least one pigment includes TiO.sub.2, CaCO.sub.3
or clay. Generally, the mean particle sizes of the pigments range
from about 0.01 to about 50 microns. For example, the TiO.sub.2
particles used in the aqueous coating composition typically have a
mean particle size of from about 0.15 to about 0.40 microns. The
pigment can be added to the aqueous coating composition as a powder
or in slurry form. The pigment is preferably present in the aqueous
coating composition in an amount from about 5 to about 50 percent
by weight, more preferably from about 10 to about 40 percent by
weight.
[0015] The coating composition can optionally contain additives
such as one or more film-forming aids or coalescing agents.
Suitable firm-forming aids or coalescing agents include
plasticizers and drying retarders such as high boiling point polar
solvents. Other conventional coating additives such as, for
example, dispersants, additional surfactants (i.e. wetting agents),
rheology modifiers, defoamers, thickeners, biocides, mildewcides,
colorants such as colored pigments and dyes, waxes, perfumes,
co-solvents, and the like, can also be used in accordance with the
invention. For example, non-ionic and/or ionic (e.g. anionic or
cationic) surfactants can be used to produce the polymer latex.
These additives are typically present in the aqueous coating
composition in an amount from 0 to about 15% by weight, more
preferably from about 1 to about 10% by weight based on the total
weight of the coating composition.
[0016] As mentioned above, the aqueous coating composition includes
less than 3.0% of antifreeze agents based on the total weight of
the aqueous coating composition. Exemplary anti-freeze agents
include ethylene glycol, diethylene glycol, propylene glycol,
glycerol (1,2,3-trihydroxypropane), ethanol, methanol,
1-methoxy-2-propanol, 2-amino-2-methyl-1-propanol, and FTS-365 (a
freeze-thaw stabilizer from Inovachem Specialty Chemicals). More
preferably, the aqueous coating composition includes less than 1.0%
or is substantially free (e.g. includes less than 0.1%) of
anti-freeze agents. Accordingly, the aqueous coating composition of
the invention preferably has a VOC level of less than about 100 g/L
and more preferably less than or equal to about 50 g/L. Despite the
fact that the aqueous coating compositions of the invention include
little or no anti-freeze agents, the compositions possess
freeze-thaw stabilities at levels desirable in the art. For
example, the aqueous coating compositions of the invention can be
subjected to freeze-thaw cycles using ASTM method D2243-82 without
coagulation. The aqueous coating compositions can also pass a
draw-down test performed by the method discussed below.
Furthermore, the aqueous coating compositions of the invention
exhibit good heat storage stability and exhibit Stormer viscosity
increases of less than 15KU, more preferably of 10KU or lower,
after being stored for 14 days at 50.degree. C. by the method
discussed below.
[0017] The balance of the aqueous coating composition of the
invention is water. Although much of the water is present in the
polymer latex dispersion and in other components of the aqueous
coating composition, water is generally also added separately to
the aqueous coating composition. Typically, the aqueous coating
composition includes from about 10% to about 85% by weight and more
preferably from about 35% to about 80% by weight water. Stated
differently, the total solids content of the aqueous coating
composition is typically from about 15% to about 90%, more
preferably, from about 20% to about 65%.
[0018] The coating compositions are typically formulated such that
the dried coatings comprise at least 10% by volume of dry polymer
solids, and additionally 5 to 90% by volume of non-polymeric solids
in the form of pigments. The dried coatings can also include
additives such as plasticizers, dispersants, surfactants, rheology
modifiers, defoamers, thickeners, biocides, mildewcides, colorants,
waxes, and the like, that do not evaporate upon drying of the
coating composition.
[0019] In one preferred embodiment of the invention, the aqueous
coating composition is a latex paint composition comprising at
least one latex polymer derived from at least one acrylic monomer
selected from the group consisting of acrylic acid, acrylic acid
esters, methacrylic acid, and methacrylic acid esters and at least
one polymerizable alkoxylated surfactant; at least one pigment and
water. As mentioned above, the at least one latex polymer can be a
pure acrylic, a styrene acrylic, a vinyl acrylic or an acrylated
ethylene vinyl acetate copolymer.
[0020] The present invention further includes a method of preparing
an aqueous coating composition by mixing together at least one
latex polymer derived from at least one monomer and at least one
polymerizable alkoxylated surfactant as described above, and at
least one pigment. Preferably, the latex polymer is in the form of
a latex polymer dispersion. The additives discussed above can be
added in any suitable order to the latex polymer, the pigment, or
combinations thereof, to provide these additives in the aqueous
coating composition. In the case of paint formulations, the aqueous
coating composition preferably has a pH of from 7 to 10.
[0021] The latex polymer including the polymerizable alkoxylated
surfactants of the invention can be used in combination with other
ionic or non-ionic type of surfactants that are either
polymerizable or non-polymerizable, in the aqueous coating
composition. In particular, the polymer latex binder can be
prepared using emulsion polymerization by feeding the monomers used
to form the latex binder to a reactor in the presence of at least
one initiator and the at least one polymerizable alkoxylated
surfactant of the invention and polymerizing the monomers to
produce the latex binder. The monomers fed to a reactor to prepare
the polymer latex binder preferably include at least one acrylic
monomer selected from the group consisting of acrylic acid, acrylic
acid esters, methacrylic acid, and methacrylic acid esters. In
addition, the monomers can include styrene, vinyl acetate, or
ethylene. The monomers can also include one or more monomers
selected from the group consisting of styrene, .alpha.-methyl
styrene, vinyl chloride, acrylonitrile, methacrylonitrile, ureido
methacrylate, vinyl acetate, vinyl esters_of branched tertiary
monocarboxylic acids, itaconic acid, crotonic acid, maleic acid,
fumaric acid, and ethylene. It is also possible to include C4-C8
conjugated dienes such as 1,3-butadiene, isoprene or chloroprene.
Preferably, the monomers include one or more monomers selected from
the group consisting of n-butyl acrylate, methyl methacrylate,
styrene and 2-ethylhexyl acrylate. The initiator can be any
initiator known in the art for use in emulsion polymerization such
as ammonium, sodium or potassium persulfate, or a redox system that
typically includes an oxidant and a reducing agent. Commonly used
redox initiation systems are described e.g., by A. S. Sarac in
Progress in Polymer Science 24(1999), 1149-1204.
[0022] The polymer latex binder can be produced by first preparing
an initiator solution comprising the initiator and water. A monomer
pre-emulsion is also prepared comprising at least a portion of the
monomers to be used to form the latex polymer, one or more
surfactants, water, and additional additives such as NaOH. The one
or more surfactants in the monomer pre-emulsion include the
polymerizable alkoxylated surfactant of the invention. The
initiator solution and monomer pre-emulsion are then continuously
added to the reactor over a predetermined period of time (e.g.
1.5-5 hours) to cause polymerization of the monomers and to thereby
produce the latex polymer. Preferably, at least a portion of the
initiator solution is added to the reactor prior to adding the
monomer pre-emulsion. Prior to the addition of the initiator
solution and the monomer pre-emulsion, a seed latex such as a
polystyrene seed latex can be added to the reactor. The seed latex
is used to obtain a uniform particle size distribution and does not
influence the freeze-thaw stability of the paint. In addition,
water, one or more surfactants, and any monomers not provided in
the monomer pre-emulsion can be added to the reactor prior to
adding the initiator and adding the monomer pre-emulsion. The
reactor is operated at an elevated temperature at least until all
the monomers are fed to produce the polymer latex binder. Once the
polymer latex binder is prepared, it is preferably chemically
stripped thereby decreasing its residual monomer content.
Preferably, it is chemically stripped by continuously adding an
oxidant such as a peroxide (e.g. t-butylhydroperoxide) and a
reducing agent (e.g. sodium acetone bisulfite), or another redox
pair such as those described by A. S. Sarac in Progress in Polymer
Science 24(1999), 1149-1204, to the latex binder at an elevated
temperature and for a predetermined period of time (e.g. 0.5
hours). The pH of the latex binder can then be adjusted and a
biocide or other additives added after the chemical stripping
step.
[0023] The aqueous coating composition is a stable fluid that can
be applied to a wide variety of materials such as, for example,
paper, wood, concrete, metal, glass, ceramics, plastics, plaster,
and roofing substrates such as asphaltic coatings, roofing felts,
foamed polyurethane insulation; or to previously painted, primed,
undercoated, worn, or weathered substrates. The aqueous coating
composition of the invention can be applied to the materials by a
variety of techniques well known in the art such as, for example,
brush, rollers, mops, air-assisted or airless spray, electrostatic
spray, and the like.
[0024] The present invention will now be further described by the
following non-limiting examples.
EXAMPLE 1 (E1)
[0025] Example 1 illustrates the preparation of a polymer
dispersion containing 2.0% (weight percent of active material based
on dry polymer weight) NOIGEN.RTM. RN-10 surfactant (commercially
available from Montello, Inc. representing Dai-lchi Kogyo Seiyaku
Co., Ltd.). NOIGEN.RTM. RN-10 surfactant has the following
structure: ##STR1##
[0026] A monomer pre-emulsion was prepared by emulsifying 264 parts
water, 37.5 parts CALSOFT.RTM. L-40 surfactant (a sodium linear or
branched alkyl benzene sulfonate surfactant commercially available
from Pilot Chemical), 20.0 parts NOIGEN.RTM. RN-10 surfactant, 15.0
parts NaOH solution (10% solution in water), 7.5 parts itaconic
acid, 20 parts ureido methacrylate, 511.2 parts n-butyl acrylate
and 461.0 parts methyl methacrylate. The initiator solution was
prepared by dissolving 2.5 parts ammonium persulfate in 47.5 parts
water. A 2-liter stirred glass reactor filled with 272.4 parts
deionized water and 3.14 parts of a 33% polystyrene seed latex was
purged with nitrogen and heated to 85.degree. C. When the
temperature was reached, the initiator solution was continuously
fed into the reactor over 4.5 hours and the monomer pre-emulsion
was continuously fed into the reactor over 4.0 hours. The reaction
was further allowed to continue for 30 minutes before being cooled
down to 60.degree. C.
[0027] To further reduce the residual monomer level, a chemical
stripping step was conducted. A peroxide solution was prepared
consisting of 1.43 parts of t-butylhydroperoxide solution (tBHP,
70% in water) and 6.7 parts of sodium acetone bi-sulfite solution
(SABS) and fed to the reactor over 45 minutes. After the addition
of tBHP and SABS, the reactor was maintained at 60.degree. C. for
30 minutes before being cooled down to room temperature. The pH of
the latex was adjusted to 8.3 with concentrated ammonia. The
resulting polymer dispersion had a solids content of 60.1% and a
diameter of 280 nm by photocorrelation spectroscopy.
EXAMPLE 2 (E2)
[0028] Example 2 illustrates the preparation of a polymer
dispersion containing 2.0% (weight percent of active material based
on dry polymer weight) HITENOL.RTM. BC-10 surfactant (commercially
available from Montello, Inc. representing Dai-lchi Kogyo Seiyaku
Co., Ltd.). HITENOL.RTM. BC-10 surfactant has the following
structure: ##STR2##
[0029] The ingredients and process used for synthesis were the same
as used in Example 1 except 20.0 parts of HITENOL.RTM. BC-10
surfactant was used instead of NOIGEN.RTM. RN-10 surfactant. The
resulting polymer dispersion had a solids content of 60.5% and a
diameter of 280 nm by photocorrelation spectroscopy.
EXAMPLE 3 (E3)
[0030] Example 3 illustrates the preparation of a polymer
dispersion containing 2.0% (weight percent of active material based
on dry polymer weight) HITENOL.RTM. BC-20 surfactant (commercially
available from Montello, Inc. representing Dai-lchi Kogyo Seiyaku
Co., Ltd.). HITENOL.RTM. BC-20 surfactant has the following
structure: ##STR3##
[0031] The ingredients and process used for synthesis were the same
as used in Example 1 except 20.0 parts of HITENOL.RTM. BC-20
surfactant was used instead of NOIGEN.RTM.) RN-10 surfactant. The
resulting polymer dispersion had a solids content of 59.8% and a
diameter of 280 nm by photocorrelation spectroscopy.
EXAMPLE 4a (E4a)
[0032] Example 4a illustrates the preparation of a polymer
dispersion containing 1.5% (weight percent of active material based
on dry polymer weight) PLURIOL.RTM. A1OR (commercially available
from BASF AG). PLURIOL.RTM. A10R has the following structure:
##STR4##
[0033] A monomer pre-emulsion was prepared by emulsifying 176 parts
water, 73.3 parts PLURAFAC.RTM. A-38 surfactant (C18-alkyl
ethoxylate with 25 EO units, 15% solution in water from BASF) 58.7
parts DISPONIL.RTM. FES 77 surfactant (sodium sulfonate of
C12-C14-alkyl ethoxylate with 30 EO units, commercially available
from Cognis, 30% solution in water), 16.5 parts sodium hydroxide
(10% aqueous solution), 16.5 parts PLURIOL.RTM. A10R, 5.5 parts
acrylic acid, 11 parts acrylic amide (50%), 8.25 parts itaconic
acid, 88 parts Mhoromer 6844-0
(N-(-2-Methacryloyloxy-ethyl)ethylene urea, 25% in MMA from Roehm,
Darmstadt, Germany), 333 parts methyl methacrylate and 660 parts
n-butyl acrylate. The initiator solution was prepared by dissolving
2.75 parts ammonium persulfate in 52.25 parts water. A 2-liter
stirred glass reactor filled with 340 parts deionised water and 3.3
parts of a 33% polystyrene seed latex was purged with nitrogen and
heated to 85.degree. C. When the temperature was reached, 10% of
the initiator solution was added. After 6 minutes, the remaining
initiator solution was continuously fed into the reactor over 4.5
hours and 4% of the monomer pre-emulsion was fed into the reactor
over 40 minutes. The rest of the pre-emulsion was continuously fed
over 190 min, afterwards, 44.7 parts water were added. The reaction
was further allowed to continue for 30 minutes. After cooling to
60.degree. C., the latex was partially neutralized with 6.6 parts
concentrated ammonia.
[0034] To further reduce the residual monomer level, a chemical
stripping step was conducted. 11 parts of t-butylhydroperoxide
solution (tBHP, 10% in water) and 14.6 parts of sodium acetone
bisulfite solution (SABS) were fed synchronously to the reactor
over 40 minutes. Afterwards, the reactor was maintained at
60.degree. C. for 20 minutes before being cooled down to room
temperature. The pH of the latex was adjusted to 8.5 with
concentrated ammonia. The resulting polymer dispersion had a solids
content of 60.4% and a diameter of 235 nm by photocorrelation
spectroscopy.
EXAMPLE 4b (E4b)
[0035] Example 4b illustrates the preparation of a polymer
dispersion containing 3.0% (weight percent of active material based
on dry polymer weight) PLURIOL.RTM. A10R. The ingredients and
process used for synthesis were the same as used in Example 5a
except that 33 parts of PLURIOL.RTM. A10R were used instead of 16.5
parts. The resulting polymer dispersion had a solids content of
60.5% and a diameter of 214 nm by photocorrelation
spectroscopy.
EXAMPLE 5 (E5)
[0036] Example 5 illustrates the preparation of a polymer
dispersion containing 1.5% (weight percent of active material based
on dry polymer weight) PLURIOL.RTM. A10R (commercially available
from BASF AG) and 2-ethylhexyl acrylate as main monomer.
[0037] A monomer pre-emulsion was prepared by emulsifying 240 parts
water, 39.6 parts Arylsulfonat surfactant (15% solution in water),
9.0 parts PLURIOL.RTM. A10R, 4.8 parts. methacrylic acid, 282 parts
methyl methacrylate and 313 parts 2-ethylhexyl acrylate. The
initiator solution was prepared by dissolving 2.4 parts ammonium
persulfate in 108 parts water. A 1.5-liter stirred glass reactor
filled with 217 parts deionised water was purged with nitrogen and
heated to 78.degree. C. When the temperature was reached, 10% of
the initiator solution and 1% of the monomer pre-emulsion were
added. After 20 minutes, the remaining initiator solution was
continuously fed into the reactor over 4.5 hours and the
pre-emulsion was continuously fed over 4.0 hours. The reaction was
further allowed to continue for 10 minutes and cooled down to
65.degree. C.
[0038] To further reduce the residual monomer level, a chemical
stripping step was conducted. 2.4 parts of t-butylhydroperoxide
solution (tBHP, 10% in water) and 4.2 parts of Rongalit.RTM. C
(BASF) solution were fed synchronously to the reactor over 40
minutes. Afterwards, the reactor was cooled down to room
temperature. The pH of the latex was adjusted to 8.0 with
concentrated ammonia. The resulting polymer dispersion had a solids
content of 50.9% and a diameter of 287 nm by photocorrelation
spectroscopy.
COMPARATIVE EXAMPLE 1 (CE19)
[0039] Comparative Example 1 illustrates the preparation of a
polymer dispersion containing 2.0% (weight percent of active
material based on dry polymer weight) LUTENSOL.RTM. AP-10
surfactant (commercially available from BASF Corporation).
LUTENSOL.RTM. AP-10 has the following structure: ##STR5##
[0040] The ingredients and process used for synthesis were the same
as used in Example 1 except 20.0 parts of LUTENSOL.RTM. AP-10
surfactant was used instead of NOIGEN.RTM. RN-10 surfactant. The
resulting polymer dispersion had a solids content of 61.15% and a
diameter of 280 nm by photocorrelation spectroscopy.
COMPARATIVE EXAMPLE 2 (CE2)
[0041] Comparative Example 2 illustrates the preparation of a
polymer dispersion containing 2.0% (weight percent of active
material based on dry polymer weight) IGEPAL.RTM. CA 877 surfactant
(commercially available from GAF Corporation). IGEPAL.RTM. CA 877
surfactant has the following structure: ##STR6##
[0042] The ingredients and process used for synthesis were the same
as used in Example 1 except 20.0 parts of IGEPAL.RTM. CA 877
surfactant (70% activity) was used instead of NOIGEN.RTM. RN-10
surfactant. The resulting polymer dispersion had a solids content
of 60.16% and a diameter of 280 nm by photocorrelation
spectroscopy.
COMPARATIVE EXAMPLE 3 (CE3)
[0043] Comparative Example 3 illustrates the preparation of a
polymer dispersion containing 2.0% (weight percent of active
material based on dry polymer weight) EMULGATOR.RTM. 925 S
surfactant (commercially available from BASF Corporation).
EMULGATOR.RTM. 925 S surfactant has the following structure:
##STR7##
[0044] The ingredients and process used for synthesis were the same
as used in Example 1 except 20.0 parts of EMULGATOR.RTM. 925 S
surfactant (70% activity) was used instead of NOIGEN.RTM. RN-10
surfactant. The resulting polymer dispersion had a solids content
of 60.89% and a diameter of 280 nm by photocorrelation
spectroscopy.
COMPARATIVE EXAMPLE 4 (CE4)
[0045] Comparative Example 4 illustrates the preparation of a
polymer dispersion without PLURIOL.RTM. A10OR. The ingredients and
process used for synthesis were the same as used in Example 5a
except that no PLURIOL.RTM. A10R was used instead of 16.5 parts.
The resulting polymer dispersion had a solids content of 60.0% and
a diameter of 293 nm by photocorrelation spectroscopy.
COMPARATIVE EXAMPLE 5a (CE5a)
[0046] Comparative Example 5a illustrates the preparation of a
polymer dispersion containing EHA as main monomer without
PLURIOL.RTM. A10R. The ingredients and process used for synthesis
were the same as used in Example 5a except that no PLURIOL.RTM.
A10R was used instead of 9.0 parts. The resulting polymer
dispersion had a solids content of 50.8% and a diameter of 300 nm
by photocorrelation spectroscopy.
COMPARATIVE EXAMPLE 5b (CE5b)
[0047] Comparative Example 5b illustrates the preparation of a
polymer dispersion containing n-butyl acrylate as main monomer with
1.5% PLURIOL.RTM. A10OR. The ingredients and process used for
synthesis were the same as used in Example 5a except that nBA was
used instead of EHA and the relative amounts of nBA and MMA were
adjusted to get the same MFFT of the latex as in Example 5. The
resulting polymer dispersion had a solids content of 50.8% and a
diameter of 251 nm by photocorrelation spectroscopy.
Paint Formulation
[0048] The following flat paint formulation with a total VOC level
of 50 g/L was used for evaluating paint performance for examples
1-3 and comparative examples 1-3 TABLE-US-00001 Ingredients Parts
by Weight Water 193.3 PROXEL .RTM. GXL.sup.1 2.0 Propylene Glycol
7.2 NATROSOL .RTM. 330 Plus.sup.2 3.2 2-Amino-2-Methyl-Propanol
(AMP-95) 1.0 TAMOL .RTM. 1124.sup.3 6.8 TRITON .RTM. CF-10.sup.4
3.0 FOAMASTER .RTM. S.sup.5 3.0 TIONA .RTM. RCL-535.sup.6 TiO.sub.2
particles 220.1 MINEX .RTM. 4.sup.7 171.2 ICECAP .RTM. K.sup.8 63.6
Water 123.5 FOAMASTER .RTM. S 3.9 NOPCO .RTM. DSX 2000.sup.9 3.9
TEXANOL .RTM..sup.10 2.0 POLYPHASE .RTM. AF1.sup.11 6.0 Polymer
Dispersion (60% solids) 337.7 Water 20.0 The above components were
mixed in the above order using a high-speed disperser (Dispermat
from VMA-Getzmann in Reichshof, Germany). .sup.1PROXEL .RTM. GXL is
a biocide based on 1,2-benzisothiazolin-3-one commercially
available from Zeneca. .sup.2NATROSOL .RTM. 330 Plus is
hydroxyethylcellulose based polymer thickener commercially
available from Aqualon Specialties. .sup.3TAMOL .RTM. 1124 is a low
molecular weight, ammonium-based, hydrophilic polymer dispersant
comprising 50% solids and commercially available from Rohm and
Haas. .sup.4TRITON .RTM. CF-10 is a modified alkylaryl polyether
surfactant commercially available from Union Carbide.
.sup.5FOAMASTER .RTM. S is a defoamer based on a proprietary blend
of esters, oils, and silica derivatives commercially available from
Henkel Corporation. .sup.6TIONA .RTM. RCL-535 TiO2 particles
commercially available from Millennium Inorganic Chemicals.
.sup.7MINEX .RTM. 4 is a nepheline syenite extender commercially
available from Unimin Specialty Minerals. .sup.8ICECAP .RTM. K is
an anhydrous kaolin clay commercially available from Burgess
Pigment Company. .sup.9NOPCO .RTM. DSX 2000 is a thickener
commercially available from Henkel Corporation. .sup.10TEXANOL
.RTM. is a 2,2,4-trimethyl-1,3-pentanediol mono(2-methylpropanoate)
coalescing agent commercially available from Eastman Chemical.
.sup.11POLYPHASE .RTM. AF1 is a fungicide commercially available
from G. R. O'Shea Company.
Paint Formulation 2
[0049] The following flat paint formulation with a total VOC level
of 0 g/L was used for evaluating paint performance for examples 4
and comparative example 4 TABLE-US-00002 Ingredients Parts by
Weight water 99.7 Natrosol .RTM. 250 HR.sup.1) 1.1 TKPP.sup.2) 1.0
Proxel .RTM. BD 20 1.6 Tamol .RTM. 731.sup.3) 3.8 Drewplus .RTM. L
475.sup.4) 2.2 Minex .RTM. 4 86.7 Omyacarb .RTM. 10.sup.5) 30.7
Ti-Pure .RTM. R 941.sup.6) 206.7 Diafil .RTM. 525.sup.7) 8.7
Dispersion (60.0%-60.5%) 203.7 Acrysol .RTM. RM 2020.sup.8) 11.0
Drewplus .RTM. L 475 1.1 Nuocide .RTM. N 40-D [404-D].sup.9) 3.8
Nopco .RTM. DSX 1550.sup.10) 1.1 water 35.9-37.6 The ingredients
were added with stirring in the order given in the formulation.
.sup.1)Hydroxyethylcellulose based thickener from Hercules Inc.
.sup.2)BK Ladenburg, Ladenburg, Germany .sup.3)Sodium salt of a
carboxylated polyelectrolyte, 25% solution in water, for use as
dispersant from Rohm & Haas Co. Philadelphia, Pa, USA
.sup.4)Defoamer from Ashland Chemical Co., Drew Industrial
Division, Boonton, NJ, USA .sup.5)Calciumcarbonate filler, typical
particle size 12 .mu.m, Omya AG, Oftringen, Switzerland
.sup.6)Titaniumdioxide slurry, 64.5% solids content, DuPont,
Wilmington, De, USA .sup.7)Diatomeous earth filler from CR Minerals
Co., Golden, Co, USA .sup.8)Polyurethane thickener, 20% solids
content, from Rohm & Haas Co. Philadelphia, Pa, USA
.sup.9)Biocide from Creanova, Piscataway, NJ, USA .sup.10)Nonionic
rheology modifier from Cognis GmbH, Dusseldorf, Germany
Paint Formulation 3
[0050] The following flat paint formulation with a total VOC level
of 0 g/l was used for evaluating paint performance for example 5
and comparative example 5 TABLE-US-00003 Ingredients Parts by
Weight water 99.7 Natrosol .RTM. 250 HR 1.1
Tetrapotassiumpyrophosphate 1.0 Proxel .RTM. BD 20 1.6 Tamol .RTM.
731 3.8 Drewplus .RTM. L 475 2.2 Minex .RTM. 4 86.7 Omyacarb .RTM.
10 30.7 Ti-Pure .RTM. R 941 206.7 Diafil 8.7 Dispersion
(50.8%-50.9%) 241.8-242.2 Acrysol .RTM. RM 2020 11.0 Drewplus .RTM.
L 475 1.1 Nuocide .RTM. N 40-D [404-D] 3.8 Nopco .RTM. DSX 1550
1.1
Test Methods
[0051] Stormer Viscosity (in KU, Krebs Units): The Stormer
viscosity was measured according to ASTM D 562-81.
[0052] ICI Viscosity (in Poise): The high shear ICI viscosity was
measured according to ASTM D 4287-94.
[0053] Heat Storage Stability: The heat storage stability of the
paints was tested by measuring the Stormer viscosity (KU) increase
after storing the paints in an 8 oz. glass jar for 14 days in a
drying oven at 50.degree. C.
[0054] Freeze-Thaw Stability: The high freeze-thaw stability of the
paints was tested according to ASTM D 2243-82. The freezer
temperature was set at -18.degree. C. Stormer viscosities were
measured after each freeze-thaw cycle, if the paint did not
coagulate.
[0055] Draw-Down of Films: After the third freeze-thaw cycle, a
draw-down of the paint was made on white sealed paper (Plain Leneta
white paper chart) with a 7 mil (about 180 .mu.m thickness) blade.
A pass or failure note was given based on the grit level in the
dried paint film. A paint film with no or sporadic microcoagulum
was rated a "pass" and a paint film with a large amount of coagulum
was rated a "fail". The rating gives information on freeze-thaw
stability of the paint to supplement the Stormer viscosity
measurement.
Paint Test Results
[0056] The test results of the flat paint formulations based on the
latices from Examples 1-5 and Comparative Examples 1-5 are
summarized in Table 1 below. TABLE-US-00004 TABLE 1 Example 1
Example 2 Example 3 Example 4a Example 4b Example 5 Stormer 86 87
76 97 98 105 Viscosity (KU) ICI Viscosity 0.64 0.65 0.54 1.0 1.1
1.2 (poise) Heat Storage 10 9 10 9 8 n.d. Stability (.DELTA.KU:KU
increase after 2 weeks at 50.degree. C. Freeze-Thaw 96/94/89/91/91
96/97/92/92/93 85/85/81/81/84 119/137/>140/>140/>140
116/127/134/136/>140 120/118/120/121/126 Stability (KU after 1,
2, 3, 4, 5 cycles) Grit in Draw Pass Pass Pass Down Films after 3
Freeze- Thaw Cycles Comparative Comparative Comparative Comparative
Comparative Comparative Example 1 Example 2 Example 3 Example 4
Example 5a Example 5b Stormer 80 72 76 90 109 106 Viscosity (KU)
ICI Viscosity 0.78 0.63 0.72 1.1 1.2 1.2 (poise) Heat Storage 16 17
26 n.d. n.d. n.d. Stability (.DELTA.KU:KU increase after 2 weeks at
50.degree. C. Freeze-Thaw Fail after 1 Fail after 1 Fail after 1
Fail after 1 Fail after 1 Fail after 1 Stability (KU cycle cycle
cycle cycle cycle cycle after 1, 2, 3, 4, 5 cycles) Grit in Draw
Fail Fail Fail Down Films after 3 Freeze- Thaw Cycles
[0057] The test results in Table 1 show that the polymerizable
surfactants of the present invention improve the freeze-thaw
stability of the paints in which they are used compared to paints
at equivalent VOC levels using conventional, non-polymerizable
surfactants. This is further evidenced by the reduced grit level in
the latex paints produced using the surfactants of the invention.
Accordingly, the amount of anti-freeze agents used in the latex
paints can be reduced when the polymerizable surfactants of the
invention are used in the manufacture of these paints without
sacrificing the freeze-thaw stability of these paints.
Additionally, freeze-thaw stability can be further enhanced by
employing EHA as soft monomer as shown in Example 5. Latex paints
produced using the surfactants of the invention also exhibit
improved heat storage stability over latex paints using
conventional additives. Furthermore, the surfactants of the
invention allow latex paints to be produced with the
above-described properties at low or zero-VOC levels. Therefore,
the latex paints produced according to the invention are more
environmentally safe than conventional paints.
[0058] It is understood that upon reading the above description of
the present invention, one skilled in the art could make changes
and variations therefrom. These changes and variations are included
in the spirit and scope of the following appended claims.
* * * * *