U.S. patent application number 12/097282 was filed with the patent office on 2009-01-08 for pigment dispersions containing aminated acrylic macromonomer dispersant.
Invention is credited to Alexei A. Gridnev, Steven Dale Ittel, Karyn B. Visscher.
Application Number | 20090012231 12/097282 |
Document ID | / |
Family ID | 38038517 |
Filed Date | 2009-01-08 |
United States Patent
Application |
20090012231 |
Kind Code |
A1 |
Ittel; Steven Dale ; et
al. |
January 8, 2009 |
PIGMENT DISPERSIONS CONTAINING AMINATED ACRYLIC MACROMONOMER
DISPERSANT
Abstract
A pigment dispersion useful for forming coating compositions
containing dispersed pigment, a carrier solvent and an aminated
macromonomer dispersant (binder) is disclosed. The aminated
macromonomer dispersant is preferably prepared by the reaction of
terminally unsaturated macromonomers synthesized by
cobalt-catalyzed chain transfer free radical polymerizations of
methacrylic monomers with monomeric or oligomeric amines.
Inventors: |
Ittel; Steven Dale;
(Wilmington, DE) ; Visscher; Karyn B.; (Voorhees,
NJ) ; Gridnev; Alexei A.; (Wilmington, DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
38038517 |
Appl. No.: |
12/097282 |
Filed: |
December 18, 2006 |
PCT Filed: |
December 18, 2006 |
PCT NO: |
PCT/US06/48236 |
371 Date: |
June 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60751233 |
Dec 16, 2005 |
|
|
|
Current U.S.
Class: |
524/607 ;
524/612 |
Current CPC
Class: |
C09D 4/00 20130101; C09D
17/007 20130101; C08F 290/14 20130101; C09D 17/003 20130101; C09D
17/005 20130101; C08F 290/06 20130101; C08F 290/061 20130101; C08F
290/141 20130101; C08F 8/32 20130101 |
Class at
Publication: |
524/607 ;
524/612 |
International
Class: |
C08G 63/00 20060101
C08G063/00; C08L 77/00 20060101 C08L077/00 |
Claims
1. A pigment dispersion composition useful for forming coating
compositions comprising a dispersed pigment, a liquid carrier and
an aminated macromonomer dispersant; wherein: the aminated
macromonomer dispersant comprises the structure ##STR00005##
wherein each R.sup.1 and R.sup.2 are independently H, alkyl of 1-20
carbon atoms, aryl, substituted alkyl of 1-20 carbon atoms, or
substituted aryl; R.sup.3 and R.sup.4 are independently H, alkyl of
1-100 carbon atoms, or substituted alkyl of 1-100 non-hydrogen
atoms or R.sup.3 is a polymer; R.sup.5 is methyl, hydrogen or
hydroxymethyl; n=1-100; m=1-100 or m+m'=2-100 and is equal to or
less than the number of reactive amino groups on R.sup.3, and;
R.sup.6 are independently-CN, --CO.sub.2R.sup.1, --COR.sup.1, or
--CONR.sup.1R.sup.1.
2. The dispersion of claim 1 wherein R.sup.3 is derived from a
polymeric amine.
3. The dispersion of claim 1 wherein R.sup.3 is derived from
polyethyleneimine.
4. The dispersion of claim 1 wherein R.sup.3 is derived from a
polymeric and polyfunctional amine.
5. The dispersion of claim 1 wherein R.sup.2 is derived from a
macromonomer of an alkyl methacrylate.
6. The dispersion of claim 1 wherein the weight ratio of pigment to
said aminated macromonomer dispersant is about 1/100-200/100.
7. The dispersion of claim 1 wherein R.sup.3 is derived from
polyethyleneimine and R.sup.2 is derived from a macromonomer of an
alkyl methacrylate.
8. The dispersion of claim 1 wherein R.sup.3 is derived from an
N-aminoalkylphthalimide, an N-aminoalkylsaccharin, an aminoalkyl
ester of nitrobenzoic acid or an aminoalkyl ester of benzoic acid
and R.sup.2 is derived from a macromonomer of an alkyl
methacrylate.
9. A coating composition comprising the pigment dispersion
composition of claim 1.
10. A substrate coated with a dried and cured layer of the coating
composition of claim 9.
11. A process for preparing the pigment dispersion of claim 1,
wherein said process comprises: a) reacting a macromonomer having
one terminal ethylenically unsaturated bond with an amine compound
to form an aminated macromonomer dispersant wherein: the resulting
aminated macromonomer dispersant comprises the structure
##STR00006## wherein each R.sup.1 and R.sup.2 are independently H,
alkyl of 1-20 carbon atoms, aryl, substituted alkyl of 1-20 carbon
atoms, or substituted aryl; R.sup.3 and R.sup.4 are independently
H, alkyl of 1-100 carbon atoms, or substituted alkyl of 1-100
non-hydrogen atoms or R.sup.3 is a polymer; R.sup.5 is methyl,
hydrogen or hydroxymethyl; n=1-100; m=1-100 or m+m'=2-100 and is
equal to or less than the number of reactive amino groups on
R.sup.3, and; R.sup.6 are independently --CN, --CO.sub.2R.sup.1,
--COR.sup.1, or --CONR.sup.1R.sup.1; b) forming, in an organic
solvent, a dispersion of said aminated macromonomers of step (a);
and c) dispersing pigment in the aminated macromonomer dispersion
to form said pigment dispersion.
12. The pigment dispersion of claim 1 wherein said liquid carrier
is an aqueous medium or organic solvent.
Description
FIELD OF THE INVENTION
[0001] This invention relates to improved pigment dispersions
containing an aminated macromonomers dispersant, and pigmented
coating compositions containing the same.
BACKGROUND OF THE INVENTION
[0002] Dispersible polymers that are used as dispersants for
pigments and used to form pigment dispersions useful in formulating
both solvent-borne and water-borne coating compositions are known
in the art. Such pigment dispersions are used in the preparation of
exterior finishes for automobiles and trucks. Government mandated
reduction of volatile organic components (VOC) in these finishes
drives a quest for ever-improving coating compositions. Dispersion
of pigments is a critical feature of the composition
formulation
[0003] An exterior automotive or truck finish containing a water
sensitive component is undesirable since for example, water
spotting and acid etching will result and the finish will be
subject to degradation by weathering. A low VOC oligomeric
dispersant is needed that will adequately disperse pigments and the
dispersant should contain a segment readily dissolved in the chosen
solvent and a segment that will attach to the surface of the
pigment to be dispersed. The inventors have found that when such a
oligomeric dispersant made from a particular macromonomer is used
in a coating composition, a finish is formed that is free from the
undesirable effects of water and weathering.
SUMMARY OF THE INVENTION
[0004] Disclosed herein is a pigment dispersion composition useful
for forming coating compositions comprising a dispersed pigment, a
carrier liquid and an aminated macromonomer dispersant; wherein:
the aminated macromonomer dispersant comprises the structure
##STR00001##
wherein each R.sup.1 and R.sup.2 are independently H, alkyl of 1-20
carbon atoms, aryl, substituted alkyl of 1-20 carbon atoms, or
substituted aryl; R.sup.3 and R.sup.4 are independently H, alkyl of
1-100 carbon atoms, or substituted alkyl of 1-100 non-hydrogen
atoms or R.sup.3 is a polymer; R.sup.5 is methyl, hydrogen or
hydroxymethyl; n=1-100; m=1-100 or m+m'=1-100 and is equal to or
less than the number of reactive amino groups on R.sup.3, and;
R.sup.6 are independently --CN, --CO.sub.2R.sup.1, --COR.sup.1, or
--CONR.sup.1R.sup.1.
[0005] Also disclosed is
DETAILED DESCRIPTION OF THE INVENTION
[0006] The novel pigment dispersion is stable and in general
non-flocculated or non-agglomerated and is compatible with a
variety of polymeric, film forming binders that are conventionally
used in coating compositions and in particular, compatible with
acrylic polymers that are used in coatings. The aminated
macromonomer dispersant, upon curing of the coating composition
into which it has been incorporated, reacts with other film forming
components of the coating composition and becomes part of the film
and does not cause deterioration of the film upon weathering as may
occur if it remained an unreacted component of the film, so, since
the aminated macromonomer is an excellent dispersant. The monomer
content of the backbone of the macromonomer can readily be adjusted
to maximize dispersion properties of the aminated macromonomer
dispersant without increasing molecular weight and not detract from
the performance properties of a coating composition into which the
pigment dispersion containing the aminated macromonomer dispersant
has been incorporated. Finishes of coatings formulated with
dispersions containing these aminated macromonomer dispersants are
hard, water and humidity resistant.
[0007] The aminated acrylic macromonomer used to formulate the
dispersion of this invention is prepared from a "macromonomer"
having the structure
##STR00002##
wherein each R.sup.1 and R.sup.2 are independently H, alkyl of 1-20
carbon atoms, aryl, substituted alkyl of 1-20 carbon atoms, or
substituted aryl and R.sup.5 is methyl, hydrogen or hydroxymethyl,
and n=1-100, preferably n=1-50. These oligomers or macromonomers
are preferably prepared by the free radical polymerization of the
appropriate monomers in the presence of a macrocyclic cobalt chain
transfer catalyst. These and related species are referred to herein
interchangeably as "oligomers," or "macromonomers" and the terms
are further intended to incorporate the products of
copolymerizations of methacrylates with other methacrylates as well
as with acrylates and with other free-radically copolymerizable
monomers. These oligomers and their production are described in a
series of U.S. patents issued to DuPont that include U.S. Pat. No.
6,624,261, U.S. Pat. No. 6,388,036, U.S. Pat. No. 6,117,958, U.S.
Pat. No. 5,883,206, U.S. Pat. No. 5,587,431, U.S. Pat. No.
5,028,677, U.S. Pat. No. 4,886,861, U.S. Pat. No. 4,694,054, and
U.S. Pat. No. 4,680,352.
[0008] As used herein, the term "acrylic" is a general term meant
to encompass a variety of ethylenically unsaturated monomers and
comonomers that may be copolymerized with methacrylate monomers to
form the oligomers or macromonomers employed in this disclosure.
Thus the resulting macromonomers may comprise a variety of
methacrylate ester monomers, acrylate ester monomers, styrene and
alpha-methylstyrene, acrylonitrile and methacrylonitrile monomers.
Other comonomers such as methylenebutyrolactone,
vinylpyrrolidinone, chloroprene, vinyl acetate may also be
incorporated into the macromonomers in lesser amounts.
[0009] The resulting aminated macromonomer dispersants comprise the
structure
##STR00003##
wherein each R.sup.1 and R.sup.2 are independently H, alkyl of 1-20
carbon atoms, aryl, substituted alkyl of 1-20 carbon atoms, or
substituted aryl; R.sup.3 and R.sup.4 are independently H, alkyl of
1-100 carbon atoms, or substituted alkyl of 1-100 non-hydrogen
atoms or R.sup.3 is a polymer; R.sup.5 is methyl, hydrogen or
hydroxymethyl; n=1-100; m=1-100 or m+m'=1-100 and is equal to or
less than the number of reactive amino groups on R.sup.3, and;
R.sup.6 are independently --CN, --CO.sub.2R.sup.1, --COR.sup.1, or
--CONR.sup.1R.sup.1.
[0010] As distinguished from the terms oligomers or macromonomers
that are used to describe the acrylic portion of the aminated
products described herein, the term "polymer" or "polymeric" is
used herein to refer to the portion of the aminated products
derived from the amine-containing species and is specified as
R.sup.3 in the structures above. When R.sup.3 is polymeric, the
polymer may be derived from monomers such as ethylene oxide, or
ethyleneimine. A polymeric system derived from ethylene oxide is
terminated with an amino group. A system derived from ethyleneimine
contains a plurality of amino groups. Amino-terminated polyethylene
or amine-terminated nylon are other examples of polymeric amines
suitable for use in this disclosure. R.sup.3 also includes species
with molecular weights up to a million, or more frequently having
molecular weights of hundreds to thousands. The distinction between
molecular amines and polymeric amines is based largely upon their
derivation and the two classes of species represent a continuum.
For example, decylamine may be considered to be a very low
molecular weight version of amine-terminated polyethylene,
H(C.sub.2H.sub.4).sub.nNH.sub.2 where n=5. Another family of
suitable polymeric amine is based upon polymers of 2-aminoethyl
methacrylate, so it is possible that R.sup.3 incorporates acrylic
monomers.
[0011] The substituent R.sup.1 on the ester group is selected from
alkyl or substituted alkyl groups, aryl groups, and substituted
aryl groups. The terminal substituent, R.sup.2, on the ester group
is selected from hydrogen atom, alkyl substituted alkyl aryl and
substituted aryl.
[0012] By "alkyl" is meant a linear or branched saturated
hydrocarbyl unit ranging from methyl, ethyl, propyl, to much higher
carbon numbers including polymeric species. Branched alkyl includes
isopropyl, isobutyl, sec-butyl, neopentyl, and much higher carbon
numbers including polymeric species.
[0013] A "substituted alkyl" is an alkyl having a non-hydrogen
functionality attached to or in place of any of the carbon atoms of
the alkyl. The substituents may be the same or different and
selected, for example, from carboxylic ester, hydroxyl, alkoxy,
tertiary amino, trifluoromethyl, perfluoroalkyl and other
substituted and unsubstituted alkyl, substituted and unsubstituted
aryl, substituted and unsubstituted olefin and halogen. Substituted
alkyl also includes species in which one or more of the carbon
atoms other than the first carbon atom of the alkyl are substituted
with heteroatoms such as oxygen, sulfur, silicon, tin or other
elements. Substituted alkyl groups generally do not bear
functionality that can react with amines under the conditions of
the reactions disclosed herein. If such reactions can occur, they
are taken into consideration when formulating a stoichiometry for
the reaction. For instance, a glycidyl group would be an
inappropriate choice of substituted alkyl because it is well known
to those skilled in the art that amines will cause a ring-opening
reaction of the epoxy functionality. Carboxylic acids will react
with the amines to form ammonium salts thereby inhibiting the
reaction.
[0014] Preferred alkyl or substituted alkyl groups include methyl,
ethyl, propyls (all isomers), butyls (all isomers), 2-ethylhexyl,
isobornyl, octyl (all isomers), higher normal and branched alkyls,
and cyclohexyl. Benzyl and substituted benzyls, neophyl,
phenylethyl, and naphthylmethyl are preferred examples of
arylalkyls, a class of substituted alkyls. Preferred examples of
substituted alkyl groups include 2-hydroxyethyl, 2-hydroxypropyl,
trimethoxysilylpropyl, methoxyethyl, trimethylsilylmethyl,
11-carbomethoxyundecyl, trimethoxysilylpropyl, methylthiopropyl,
trifluoromethyl, 6,6,6-trifluorohexyl, triethoxysilylpropyl,
tributoxysilylpropyl, dimethoxymethylsilylpropyl,
diethoxymethylsilylpropyl, dibutoxymethylsilylpropyl,
diisopropoxymethylsilylpropyl, dimethoxysilylpropyl,
diethoxysilylpropyl, dibutoxysilylpropyl, diisopropoxysilylpropyl,
2-(oxyethyl hydrogen propanedioate) and trimethylsilylmethyl.
[0015] By "aryl" is meant aromatic groups, including aryl and
heteroaryl rings, examples being phenyl, naphthyl, pyridyl,
pyrimidyl, benzoxoylanthracenyl.
[0016] "Substituted aryl" refers to aromatic groups substituted
with functional substituents being the same or different and
selected, for example, from carboxylic ester, hydroxyl, alkoxy,
amino, secondary amino, tertiary amino, trifluoromethyl,
perfluoroalkyl and other substituted and unsubstituted alkyl,
substituted and unsubstituted aryl, substituted and unsubstituted
olefin and halogen.
[0017] The substituent R.sup.2 on the oligomer backbone is
generally a hydrogen atom, derived from the catalytic chain
transfer process, though it is not limited to such. R.sup.2 may be
selected from alkyls, substituted alkyls, aryls and substituted
aryls. R.sup.2 may originate from copolymerizations of methacrylic
monomers with acrylic monomers, particularly those resulting from
cobalt-catalyzed chain transfer as disclosed, for example, in U.S.
Pat. No. 6,624,261; from chain initiation with a non-polymerizable
monomer as disclosed, for example, in U.S. Pat. No. 6,117,958; or
from chain transfer in an acrylic polymerization when methacrylate
macromonomers are utilized as chain transfer reagents, as
disclosed, for example, in U.S. Pat. No. 5,773,534 and U.S. Pat.
No. 5,264,530. Finally, R.sup.2 may originate from conventional
chemical syntheses or modifications.
[0018] Amine-functionalized compounds are one of the most diverse
classes of organic molecules. Thus, a reaction with amines can
bring a wide range of new functionalities to their reaction
products. In preferred embodiments, amine functionalities include
amines
R.sup.3--NH.sub.2
and
R.sup.3R.sup.4NH
wherein the substituents R.sup.3 and R.sup.4 on the amine are
selected from a hydrogen atom, alkyl groups, and functionalized
alkyl groups. Preferred functional groups include methyl, ethyl,
propyls (all isomers), butyls (all isomers), 2-ethylhexyl,
isobornyl, benzyl and substituted benzyls, cyclohexyl,
2-hydroxyethyl, 2-hydroxypropyl, trimethoxysilylpropyl,
triethoxysilylpropyl, tributoxysilylpropyl,
dimethoxymethylsilylpropyl, diethoxymethylsilylpropyl,
dibutoxymethylsilylpropyl, diisopropoxymethylsilylpropyl,
dimethoxysilylpropyl, diethoxysilylpropyl, dibutoxysilylpropyl,
diisopropoxysilylpropyl, and higher normal and branched alkyls.
Further included in the amines are bifunctional amines,
polyfunctional amines, and polymeric amines. R.sup.3 and R.sup.4
may be combined in a cyclic structure. Examples of ring structures
include piperidine, piperazine, 4'-piperazineacetophenone. R.sup.3
and R.sup.4 may be constituents of polyfunctional amines,
bifunctional amines or diamines, polyfunctional amines or polymeric
amines.
[0019] "Bifunctional amine" or "diamine" means an organic moiety
having two amino groups that will be active in the reaction or
process described herein. Examples would include ethylenediamine,
1,6-hexamethylenediamine, 1,4-bis(aminomethyl)benzene,
diamino-terminated polyethyleneoxide, or diaminopropyl-terminated
poly(dimethylsiloxane). Hydrazine and substituted hydrazines would
be the most simple diamines.
[0020] "Polyfunctional amine" means an organic moiety having two or
more amino groups that are active in the reactions and processes
disclosed herein. Examples include tris(aminoethyl)amine,
amino-ethyl-functionalized polystyrene, and
aminopropyl-functionalized poly(dimethylsiloxane).
[0021] "Polymeric amine" means an amino-containing organic moiety
based upon a polymeric backbone. The amino group may be in the
backbone of the polymer or may be pendant to it.
[0022] The polymeric amines are a more limited but nonetheless
significant class of amines. They range from polymers terminated
with a single amine group to polymers in which amine functionality
is incorporated into each repeat group in the polymer backbone.
Examples include diamino-terminated polyethyleneoxide,
diaminopropyl-terminated poly(dimethylsiloxane),
amino-ethyl-functionalized polystyrene, aminopropyl-functionalized
poly(dimethylsiloxane), and in particular, linear and branched
polyethyleneimine.
[0023] By "reactive amino groups" is meant those amino groups that
are capable of undergoing the reactions described herein, as
opposed to "unreactive amino groups." Tertiary amines have no
reactive hydrogen atom and are thus incapable of being "reactive
amino groups." Other unreactive amino groups are those which are
too sterically encumbered to undergo reaction or chemically
deactivated by being attached to aromatic groups. A "reactive amino
group" may be rendered unreactive by being too close to another
reactive amino group in the same molecule such that when the other
reactive amino group has reacted, the sterics become too crowded
for a second reaction. Tertiary alkyl groups can render amines
unreactive as can multiple isoalkyl groups.
[0024] As used herein, the term "derived from" refers to the origin
of substituents (Q or R.sup.3) that are part of the disclosed
compositions and that originated from the diverse range of amines
that are reacted with the products of catalytic chain transfer. For
instance, in a compound derived from the amine
R.sup.3--NH.sub.2
if R.sup.3 is octyl, then the substituent octyl is said to have
been derived from the amine, octylamine or 1-aminooctane. The
products can similarly be derived from diamines H.sub.2N-Q-NH.sub.2
in which case an oligomer would add to one or preferably both amino
groups. For instance, if 1,6-hexanediamine were employed, the Q
derived from that reaction would be the hexamethylene group,
--(CH.sub.2).sub.6--. When polymeric polyamines are employed, Q
becomes the polymeric backbone without the amine groups. It is not
expected that addition will be complete; some or many of the
pendant amine groups will remain unreacted, particularly if the
amine groups are closely spaced down the polymer backbone.
[0025] The aminated macromonomers are most effective dispersants
when they have been functionalized with groups that interact with
and/or attach to the pigment surface, also known as "pigment
anchoring groups". Pigment anchoring groups selectively associate
with the surface of the pigments, thereby anchoring of the aminated
macromonomer dispersant to that pigment particle. Anchoring groups
frequently employed include but are not limited to aromatic esters,
aromatic amines, imides, aliphatic amines, aromatic nitrogen
heterocycles, and quaternary ammonium compound. The anchoring
segment can be attached to the macromonomer by reacting amine
functional groups on the anchoring molecules with the unsaturation
of the macromonomer.
[0026] The aromatic ester anchoring groups can be attached as
pendant groups to the macromonomer through pendant aminoalkyl
groups. The esters of the aromatic carboxylic acids useful herein
may be unsubstituted or may contain substituents, such as, e.g.,
nitro groups, hydroxy, amino, ester, acryloxy, amide, nitrile,
halogen, haloalkyl, alkoxy, and the like. Examples include
aminoalkyl esters of benzoic acid, 2-nitrobenzoic acid,
3-nitrobenzoic acid, 4-nitrobenzoic acid, 3,5-dinitrobenzoic acid,
1-naphthoic acid, 3-chlorobenzoic acid, 4-biphenyl carboxylic acid,
4-sulfamido benzoic acid, nicotinic acid, and the like. Useful
aminoalkyl compounds for esterification include aminoethanol and
aminopropanol. Alternatively, the reactive amino functionality may
be introduced as a substituent on the aromatic ring and then the
alkyl of the ester functionality may be chosen independently.
[0027] Alternatively, the aromatic amine anchoring groups are
preferably tertiary aromatic amines. They may contain substituents
such as, e.g., hydroxy, ester, acyloxy, amide, nitrile, halogen,
haloalkyl, alkoxy, and the like. The aminoalkyl group for reaction
with the macromonomer may be incorporated into the amine group or
it may be a substituent on the aromatic ring. Examples of
N-substituted aromatic amines include
N-benzyl(aminoethyl)methylamine, N,N-dibenzyl(aminopropyl)amine, or
N-methyl-N-aminopropylaniline. Ring-substituted alkylaminoaromatic
amines include 2-(aminoethyl)pyridine,
4-aminopropyl-N,N-dimethylaniline, and the like.
[0028] Amide anchoring groups are generally based upon phthalimide,
maleimide and saccharin. Functionalization in generally through the
heterocyclic nitrogen atom and would include species such as
N-aminoalkylphthalimide, N-aminoalkylmaleimide, and
N-aminoalkylsaccharin. Alternatively, the aminoalkyl functionality
may be attached to the aromatic ring.
[0029] Quaternary ammonium compounds are effective groups for
anchoring pigment particles. Aminated macromonomers containing
quaternary ammonium functionality will generally be prepared by the
addition of polyamines to the macromonomers followed by subsequent
quaternization. Some polyamines are rich enough in quaternary sites
that subsequent quaternization is not required. A good example
would be polyethyleneimine.
[0030] Certain pigments are effectively anchored by nitrogen
heterocycles. The nicotinic acid derivatives above would fall into
this class of anchors, but the class would also include compounds
such as 4-(3-aminopropyl)morpholine, 3-aminomethylpyridine, and
1-(3-aminopropyl)imidazole.
[0031] Alternatively, aromatic amine containing monomers, such as
4-aminostyrene, 2-vinyl pyridine, 4-vinyl pyridine, and the like,
may be directly copolymerized into the macromonomer to form the
aromatic amine anchoring groups, if desired.
[0032] It has been found that improved coating compositions are
obtained by using the aminated macromonomers as dispersants for
pigments. The compositions also contain a film forming binder
usually an acrylic polymer and a curing agent. Such compositions
have the advantage of providing excellent coating properties
desirable for automotive finishes.
[0033] The coatings compositions of this invention contain in
addition to the pigment dispersion a binder preferably of an
acrylic-based polymer and a crosslinking agent such as a melamine
crosslinking agent, a polyisocyanate crosslinking agent or a
blocked polyisocyanate crosslinking agent, in a liquid carrier. The
liquid carrier can be an organic solvent, water, and water and
organic co-solvent blend.
[0034] When the dispersion containing the aminated macromonomer
dispersant is used in an aqueous coating composition, the
film-forming copolymers form stable solutions or dispersions. These
coating compositions also contain about 10-70%, more typically
15-50% by weight of binder, and about 30-90%, more typically 50-85%
by weight, of the liquid carrier which is water alone or a mixture
of mainly water and customary water-soluble organic solvent or
blend. Suitable coating compositions are prepared by blending other
useful components in accordance with normal paint formulation
techniques.
[0035] The acrylic based polymer binders typically are polymers of
alkyl (meth)acrylates having 1-12 carbon atoms in the alkyl group,
hydroxy alkyl (meth)acrylates having 1-4 carbon atoms in the alkyl
group and methacrylic or acrylic acid and have a number average
molecular weight of 5,000-30,000 and are neutralized with ammonium
hydroxide or an amine to form aqueous solutions or dispersions. The
aforementioned alkyl (meth)acrylates, hydroxy alkyl (meth)acrylates
can be used to formulate these polymers.
[0036] To form a coating composition which will crosslink under
elevated baking temperatures of about 60-180.degree. C. for about
5-60 minutes, about 10 to 50%, preferably 15 to 30% by weight,
based on the weight of the binder, of an alkylated melamine
formaldehyde crosslinking agent having 1-4 carbon atoms in the
alkylated group is preferred.
[0037] These crosslinking agents are generally partially or fully
alkylated melamine formaldehyde compounds and may be monomeric or
polymeric as described above. Blocked isocyanates can also be used
as crosslinking agents. Coating compositions containing a melamine
crosslinking agent can contain about 0.1 to 1.0% by weight, based
on the weight of binder, of a strong acid catalyst or a salt
thereof to lower curing temperatures and time. Aromatic sulfonic
acids such as para-toluene sulfonic acid or its ammonium salt are
preferred catalysts. Other catalysts that can be used are dodecyl
benzene sulfonic acid, phosphoric acid and amine or ammonium salts
of these acids.
[0038] Other film forming polymers can also be used in these
coating compositions such as urethanes, polyesters and polyester
urethanes, polyethers and polyether urethanes that are compatible
with pigment dispersions containing the aminated macromonomer
dispersants of the present invention. When the dispersion of this
invention is aqueous, a solvent can be utilized, preferably in
minimal amounts, to facilitate formulation and application of the
coating compositions formulated with dispersions of the present
invention. An organic solvent is utilized which is compatible with
the components of the composition.
[0039] To form a pigment dispersion or a millbase, pigments are
typically added to the aminated macromonomer dispersant in the
customary organic solvent or blend and are dispersed using
conventional techniques such as high speed mixing, ball milling,
sand grinding, attritor guiding, or two or three roll milling.
Dispersion may also be accomplished by passing the mixture through
a plurality of nozzles within a liquid jet interaction chamber at a
liquid pressure of at least 5,000 psi. The resulting pigment
dispersion has a pigment to aminated macromonomer dispersant weight
ratio of about 0.1/100 to 2000/100.
[0040] Any of the conventional pigments used in paints can be used
to form the pigment dispersion. Examples of suitable pigments
include metallic oxides such as titanium dioxide, iron oxides of
various colors, and zinc oxide; carbon black; filler pigments such
as talc, china clay, barytes, carbonates, and silicates; a wide
variety of organic pigments such as quinacridones, phtalocyanines,
perylenes, azo pigment, and indanthrones carbazoles such as
carbazole violet, isoindolinones, isoindolons, thioindigio reds,
and benzimidazolinones; and metallic flakes such as aluminum flake,
pearlescent flakes, and the like.
[0041] When the dispersion containing the aminated macromonomer
dispersant is used in an organic solventborne coating composition,
the film-forming binder form stable solutions or dispersions.
Suitable organic solvents will generally include polar
functionality such as organic ester, ketone, alcohol, sulfoxide,
amide or ether groups to enhance the solubility of the aminated
macromonomer dispersants. The solvent may be a blend of two or more
organic solvents. The coating compositions derived therefrom also
contain about 10-70%, more typically 15-50% by weight of binder,
and about 30-90%, more typically 50-85% by weight, of the liquid
carrier which is an organic solvent or blend or organic solvents.
Suitable coating compositions are prepared by blending other useful
components in accordance with normal paint formulation
techniques.
[0042] In addition, coating composition utilizing the dispersion of
the present invention may contain a variety of other optional
ingredients, including fillers, plasticizers, antioxidants,
surfactants and flow control agents.
[0043] To improve weatherability of a finish produced of such
coating compositions, an ultraviolet light stabilizer or a
combination of ultraviolet light stabilizers can be added in the
amount of about 0.1-5% by weight, based on the weight of the
binder. The stabilizer may be added for example to a dispersion of
this invention containing pigments or may be added directly to the
coating composition. Such stabilizers include ultraviolet light
absorbers, screeners, quenchers, and specific hindered amine light
stabilizers. Also, an antioxidant can be added, in the about 0.1-5%
by weight, based on the weight of the binder.
[0044] Typical ultraviolet light stabilizers that are useful
include benzophenones, triazoles, triazines, benzoates, hindered
amines and mixtures thereof. Specific examples of ultraviolet
stabilizers are disclosed in U.S. Pat. No. 4,591,533, the entire
disclosure of which is incorporated herein by reference.
[0045] Such coating composition may also include conventional
formulation additives such as flow control agents, for example,
"Resiflow" S (polybutylacrylate), BYK 320 and 325 (high molecular
weight polyacrylates); rheology control agents, such as fumed
silica and thickeners such as the Acrylsol B copolymers from Rohm
& Haas.
[0046] The coating composition of this invention can also include
any of the other conventional pigments used in paints in particular
paints such as metallic flakes like aluminum flake, bronze, nickel
stainless steel flakes and the like, pearlescent flakes like coated
mica flakes such as mica flakes coated with titanium dioxide and
the like, as well as carbon black, filler pigments such as talc,
china clay, barytes, carbonates, silicates, metallic oxides such as
titanium dioxide, opaque iron oxides of various colors, and zinc
oxide; carbon black, and a wide variety of organic pigments such as
quinacridones, phthalocyanines, perylenes, azo pigments,
indanthrones, carbazoles such as carbazole violet, isoindolinones,
isoindolones, thioindigo reds, benzimidazolinones, and the like.
Metallic flakes like aluminum flake is preferred.
[0047] Pigment dispersions of the present invention may be utilized
in a pigmented color coat or base coat over which a clear coat is
applied to provide a colorcoat/clearcoat finish. Also, small
amounts of pigment dispersion can be added to the clear coat to
provide special color or aesthetic effects such as tinting. The
coating compositions of the present invention may also be utilized
as a monocoat.
[0048] Coating compositions of this invention have excellent
adhesion to a variety of metallic or non-metallic substrates, such
as previously painted substrates, primed substrates, cold rolled
steel, phosphatized steel, and steel coated with conventional
electrodeposition primers. These coating compositions can be used
to coat plastic substrates such as polyester reinforced fiberglass,
reaction injection-molded urethanes and partially crystalline
polyamides. In particular, base coat or color coat composition of
this invention, provide improved transparency and reduced haze and
improved paint stability, which properties are very important
property for coatings used on automobiles and trucks.
[0049] Coating compositions formulated with the dispersion of this
invention can be applied by conventional techniques such as
spraying, electrostatic spraying, dipping, brushing, flowcoating
and the like. The preferred techniques are spraying and
electrostatic spraying.
[0050] In OEM applications, the composition is typically baked at
100-150.degree. C. for about 15-30 minutes to form a coating about
0.1-3.0 mils thick. When the composition is used as a clearcoat, it
is applied over the color coat which may be dried to a tack-free
state and cured or preferably flash dried for a short period before
the clearcoat is applied. The colorcoat/clearcoat finish is then
baked as mentioned above to provide a dried and cured finish. The
present invention is also applicable to non-baking refinish
systems, as be in the art.
[0051] It is customary to apply a clearcoat over a basecoat by
means of a "wet-on-wet" application, i.e., the clearcoat is applied
to the basecoat without curing or completely drying the basecoat.
The coated substrate is then heated for a predetermined time period
to allow simultaneous curing of the base and clear coats.
[0052] The following Examples illustrate the invention. All parts
and percentages are on a weight basis unless otherwise indicated.
All molecular weights disclosed herein are determined by GPC (gel
permeation chromatography) using a polystyrene standard.
EXAMPLES
Example 1
Preparation of polyBMA of Mn=2600
[0053] In 1 liter flask, 400 mL of butyl methacrylate (Aldrich), 25
mg tetrakis(4-methoxyphenyl)porphyrin-Co.sup.II (Aldrich) and
solution of 1.8 g VAZO-67.RTM. (DuPont) in 500 mL ethyl acetate
were mixed until homogeneous. Nitrogen gas was passed through the
solution for 30 min to remove oxygen. The temperature was raised to
80.degree. C. After 1 h, the temperature was raised to 85 C. At 2
h, the temperature was raised to 90 C, during which time some ethyl
acetate was stripped from the system. The reaction mixture was
chilled to room temperature after 6 h of heating. GPC analysis
showed that contained the expected macromonomer of BMA with Mn=2600
and Mw=4860. The oligomer was concentrated by evaporation under 0.1
mm Hg pressure to constant weight. The polyBMA content was found to
be 61% w/v.
Example 2
Preparation of Diblock Copolymer
[0054] A sample (130 mL) of the BMA macromonomer solution from
example 1 (PBMA=0.03 mol), 60 mL of dry butyl acetate and 14.2 mL
of polyethylenimine of Mn.about.423 (Aldrich, viscosity 200 cP;
0.036 mol) were mixed under nitrogen in a 250 mL flask. After
standing for 3 weeks at room temperature, the contents were
analyzed by GPC, proton NMR and MS and found to be the adduct of
the polyethyleneimine to the BMA macromonomer. In particular, the
proton NMR of the sample showed that signals from vinylic protons
(singlets at 5.5 and 6.2 ppm) had disappeared in the addition
product of polyBMA with polyethyleneimine. MS (mass-spectrometry)
was conducted using standard MALDI techniques and the resulting
spectra of mass-distribution showed not more than 10% of unreacted
polyBMA in the samples.
Example 3
Preparation of polyBMA of Mn=3260
[0055] The macromonomer was obtained in a manner analogous to
example 1 except 360 mL BMA and 15 mg
tetrakis(4-methoxyphenyl)porphyrin-Co(II) were utilized. GPC
analysis showed that obtained product contained BMA macromonomers
with Mn=3260 Hand Mw=4860. Concentration of the macromonomers in
the solution was accomplished by evaporation under 0.1 mm Hg
pressure to constant weight. The polyBMA content was found to be
42% w/v.
Example 4
Preparation of Diblock Copolymer
[0056] A sample (236 mL) of the macromonomer from example 3
(Mn=3260, 0.03 mol) was reacted with 11.9 ml of polyethylenimine of
Mn.about.423 (Aldrich, viscosity 200 cP; 0.03 mol) under nitrogen
in 250 ml flask. After 3 weeks at room temperature the content was
analyzed by GPC, proton NMR and MS and found to be the adduct of
the macromonomer with polyethyleneimine. In particular, the proton
NMR of the sample showed that signals from vinylic protons
(singlets at 5.5 and 6.2 ppm) had disappeared in the addition
product of polyBMA with polyethyleneimine. MS (mass-spectrometry)
was conducted using standard MALDI techniques and the resulting
spectra of mass-distribution showed not more than 10% of unreacted
polyBMA in the samples.
Example 5
Pigment Dispersions
[0057] Dispersion of Magenta Pigment was carried out employing the
product of Example 2 with 12 hr grind using 10% solids and a
pigment to dispersant ratio of P/D=1.5. The general procedure for
dispersion preparation was to mix the macromonomer and butyl
acetate together until well mixed and then to mix the
polymer/solvent solution with the pigment in the 01-attritor using
the following conditions:
Media=Steel Shot
[0058] Media Size=1/8 inch
Speed=350 RPM
[0059] Media Load=1816 g (full load)
Grind Time=12 h
Batch Size=350 g
[0060] Samples were drawn down onto Mylar film at 8, 10 and 12 hrs.
The haze and transmittance were monitored starting at 8 hours and
going until 12 h.
TABLE-US-00001 Time Transmittance Haze 8 hrs 17.20 10.95 10 hr
17.78 8.14 12 hr 17.09 6.89
Example 6
Pigment Dispersions
[0061] Dispersion of Magenta Pigment was carried out employing the
product of Example 4 with 12 hr grind using 10% solids and a
pigment to dispersant ratio of P/D=1.5.
TABLE-US-00002 Time Transmittance Haze 8 hrs 17.02 10.48 10 hr
17.24 8.57 12 hr 17.57 7.03
Example 7
Pigment Dispersion
[0062] Dispersion of Magenta Pigment was carried out employing the
product of Example 2 with 12 hr grind using 25% solids and a
pigment to dispersant ratio of P/D=1.5.
TABLE-US-00003 Time Transmittance Haze 8 hrs 10.69 23.71 10 hr
11.14 19.32 12 hr 10.93 17.16
Example 8
Preparation of Diblock Copolymer
[0063] A sample of the BMA macromonomer solution from example 1 and
N-(aminoethyl)phthalimide is mixed under nitrogen in a 250 mL flask
and the mixture is heated to 80.degree. C. for 8 hours under a
nitrogen atmosphere. The resulting product is
##STR00004##
Example 9
Pigment Dispersions
[0064] Dispersion of a phthalocyanine pigment is carried out
employing the product of Example 8 with 12 hr grind using 10%
solids and a pigment to dispersant ratio of P/D=1.5. An effective
dispersion is obtained.
* * * * *