Note: Descriptions are shown in the official language in which they were submitted.
1~46f~4
PIGMENT DISPERSANTS FOK COATING CO POSIT[)N5
Background of the Invention
The subject invention relates to (1) pigment dispersants,
(2) their use in pigment dispersions containing pigment and liquid carrier
and (3) coating compositions containing the pigment dispersions. The
dispersants are useful in the manufacture of a wide variety of pigmented
resin-containing coating compositions.
Pigmented coating compositions are useful for their aesthetic
as well as protective features. Such compositions contain a film-forming
resin and a pigment dispersed in a liquid carrier. It is important that
the pigment be satisfactorily dispersed throughout any film which results
from the application of the coating composition. It is therefore desirable
that the pigment be well dispersed throughout the liquid coating composition.
Typically, the pigment to be used in a coating composition is first dis-
persed with only a portion of the total film-forming resin of which the
coating composition is comprised together with appropriate liquid carriers
and addi~ives. The resulting dispersion is the;l mixed with the remainder
of the film-forming re.sin and any other necessary components to produce the
coating composition. Most pigment dispersants are very specific in their
performance and are compatible with only a small number of the diverse
solvents and film-forming resins used in coating compositions. For example,
in the case of an acrylic resin based coating composition, the pigment will
be first dispersed with a portion of the acrylic resin in the presence of
an organic solvent. The resultant product is then further diluted with
the remainder of the acrylic resin and any other necessary components
-1- . ~
~66~
forming a part of the coating composition. The final color oE the coating
composition is normally adjusted by small further additions of pigment
dispersions containing the same or similar film-forming resins just prior
to use. This further addition is normally referred to as "tinting".
A number of different film-forming resins are used in the
manufacture of different coating compositions. Accordingly, heretofore
it has been necessary to predisperse pigments with a portion of the
film-forming resin or a resin compatible therewith, which is appropri-
ate to each type of coatin~ composition. That is, even though the
pigmentation of two coating compositions containing different film-
forming resins may be identical, it has been necessary to disperse each
pigment or mixture of pigments separately with the appropriate film-
forming resin. This is necessary so as to avoid any problems of incompat-
ibility in the final coating composition. In a similar manner any tinting
operation requires the use of dispersants which are compatible with the
film-forming resin being used.
One solution to the aforementioned well~known problem has
been the development of so called "multi-purpose" pigment grinding vehicles.
The polymeric dispersants contained in the multi-purpose pigment grinding
vehicles are compatible with a wide range of film-forming resins and
solvents. It can readily be recognized that a pigment grinding vehicle
which can be used in many coating systems would be of significant savings
to the coatings industry. Thus, one set of pigment dispersions could be
used with a wide variety of coating compositions.
There have now been found dispersants based on the polymer-
ization products of specific monomeric units which are capable of acting as
multi-purpose dispersants. Such dispersants are useful for dispersing
pigments and which can then be used in resin-containing coating compositions.
1~9L6~4
As used herein all percentages arld ratios are by weight unless
otherwise indicated.
Summary of the Invent;on
.. . .
A dispersant compatible with a variety of film-forming resins
is the polymerization product of (i) from about 20 percent to about 85
percent of an alkyl methacrylate having from 3 to 8 carbon atoms in the
alkyl group, (ii) from about 5 percent to about 60 percent of a hardening
monomer selected from the group consisting of a styrene, methyl methacrylate,
ethyl methacrylate and mixtures thereof, (iii) from about 1 percent to
about 25 percent of an ethylenically unsaturated carboxylic acid selected
from the group consisting of acrylic acid, methacrylic acid, itaconic acid,
crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer
having a double bond alpha-beta to a carbonyl group and which provides
carboxyl functionality when reacted with water, alcohol, amine or anhydride,
(iv) from about 1 percent to about 25 percent of a monomer having a double
bond alpha-beta to a carbonyl group and at least one hydroxyl group or a
monomer which provides such groups when further reacted with an acid or
epoxide, and (v) from about 0.1 percent to abou~ 15 percent of a compound
providing an amine or amine salt functional moiety; and wherein said
dispersant has a weight average molecular weight as determined by gel
permeation chromatography, using a polystyrene standard of from about 1,000
to about 10,000.
The above-described dispersants are especially adap~ed for
dispersing pigments to be used in coating compositions wherein the film-
forming resin is an epoxy, vinyl, alkyd, polyester, acrylic, aminoplast,
phenolplast, cellulose derivative, amide, or urethane resin or mixtures
thereof.
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~46694
Detailed Description of the Invention
_
The invention herein described relates to (I) dispersants,
(2) pigment dispersions containing the dispersant, pigment and liquid
carrier and (3) coating compositions containing the dispersant, pig-
ment, film-forming resin and a liquid carrier.
Dispersants
The dispersants described herein are the pclymerization product
of an alkyl methacrylate, a hardening monomer, an ethylenically unsaturated
carboxylic acid or a monomer having a double bond alpha-beta to a carbonyl
group and which provides carboxyl functionality when reacted with water,
alcohol, amine or anhydride, a monomer having or providing a carbonyl
group with a double bond alpha-beta to the carbonyl group and at least one
hydroxyl group and a compound providing an amine or amine salt functional
moiety. Each of the individual components used in forming the polymer is
described in the succeeding paragraphs. The percentages of the individual
components are given on the basis of the non-volatile components.
The alkyl methacrylate is used in the formation of the polymer at
a level of from about 20 percent to about 85 perceut, preferably from about
40 percent to about 80 percent, and more preferably from about 60 percent
to about 80 percent of the reaction mixture. The alkyl methacrylates
contain from 3 to 8 carbon atoms in the alkyl chain. Examples of satis-
factory alkyl methacrylates include isopropyl mèthacrylate, butyl meth-
acrylate, isobutyl methacrylate, isoamyl methacrylate, hexyl methacrylate,
2-ethylhexyl methacrylate and octyl methacrylate. The branched chain
methacrylates are preferred with isobutyl methacrylate being the most
preferred alkyl methacrylate.
~1~6~i99~
A hardening monotner seLected from the group consisting of
a styrene, metilyl methacrylate, e~hyl methacrylate and mixtures thereof
is used in formation of the herein described polymer at a level of from
about 5 percent to about 60 percent, preferably from about 15 percent to
about 40 percent, more preferably from about 20 percent to about 35 percent.
A styrene, as used herein, is intended to include styrene and the substi-
tuted styrenes, e.g., alpha-methyl styrene, vinyl toluene, chlorostyrene,
and tert-butylstyrene. Styrene and methyl methacrylate are the preferred
hardenîng monomers.
From about 1 percent to about 25 percent, preferably from
about 1 percent to about 20 percent, more preferably from about 1 percent
to about 15 percent, of the reaction mixture comprises the ethylenically
unsaturated carboxylic acid or a monomer having a double bond alpha-beta to
a carbonyl group and which provides carboxyl functionality when reacted
with water, alcohol, amine or anhydride. The ethylenically unsaturated
carboxylic acid is selected from the group consisting of acrylic acid,
methacrylic acid, itaconic acid, crotonic acid, maleic ac;d, fumaric acid
and mixtures thereof. Acrylic acid and methacrylic acid are ~he preferred
ethylenically unsaturated carboxylic ac;ds.
Instead of polymerizing the ethylenically unsaturated carboxylic
acid into the polymer, other monomers can be used which when further
reacted provide the carboxyl functionality. Thus, alkyl acrylates such as
methyl or ethyl acrylate can be polymerized into the polymer and thereafter
hydrolyzed~ Another technique of introducing the carboxyl functionality to
the polymer is to use an unsaturated anhydride, e.g., maleic anhydride or
substituted maleic anhydride, in the initial polymeri~ation reaction
followed by the opening of the anhydride with (l) water to yield a diacid,
~9,669~
(2) an alcohol to yield an es~er acid or (3) an amine to yiel(l an amide
acid. The alcohol and amine are alkyl, aryl or cycloal;phatic in nsture
and include methyl alcohol, ethyl alcohol, 2-ethylhexyl alcohol, the
phenols and napthols, cyclohexanol, furfuryl alcohol, ethyl amine, hexyl
amine, diethyl amine, dibutyl amine, aniline, alkyl substituted anilines,
piperidine and morpholine. Still another method of providing the carboxyl
functionality in the polymer is to use a hydroxyl or amine-containing
monomer in preparing the polymer and thereafter react it with an anhydride.
The reaction of the hydroxyl group with an anhydride gives an ester acid
while the reaction of the amine group with an anhydride gives an amide -
acid. ~onomers that provide the hydroxyl groups in the polymer include the
hydroxyalkyl acrylates and methacrylates, e.g., hydroxyethyl acrylate,
hydroxypropyl acrylate and hydroxyethyl methacrylate. Monomers that
provide the amine groups include tert-butylaminoethyl methacrylate and
aziridine reaction products which furnish amine functionality pendent from
the polymer.
The polymer reaction mixture also contains from about 1 percent
to about 25 percent of a monomer having a double bond alpha-beta to a
carbonyl group and at least one hydroxyl group or a monomer which provides
such groups when further reacted with an acid or an epoxide. The preferred
level of this component ranges from about 1 percent to about 15 percent,
with the more preferred level being from about one percent to about 10
percent. Examples of monomers having a double bond alpha-beta to a carbonyl
group and at least one hydroxyl group are the monohydroxy alkyl acrylates,
alkyl methacrylates and alkyl crotonates and the mono- and dihydroxy alkyl
fumarates, itaconates, and maleates. Preferred are the hydroxyl-containing
alkyl acrylates and methacrylates with the alkyl group containing from 2
1:~4t~6~
carbon ato,~s to ~0 carbon atoms, preferably from 2 carbon atoms to 6 carl~on
atoms. Suitable hydroxyL-containing monomers ;nclude hydroxyethyl acrylate,
hydroxypropyl acrylates, hydroxyethyl methacrylate and hydroxypropyl
methacrylate, with hydroxyethyl acrylate being preferred.
Examples of monomers which provide the carbonyl group with the
alpha-beta unsaturation and at least one hydroxyl group when reacted with
an acid are the glycidyl acrylates and glycidyl methacrylates. The glycidyl
acrylate or methacrylate is reacted with the other described monomers to
form a polymerization product, which is then reacted with an acid such as
acetic acid, lauric acid, ben~oic acid, or nicotinic acid to open the
epoxide ring. It will be recognized that a nitrogen-containing acid
used to open the epoxide ring can also be used to introduce the amine
functional moiety (as below discussed) to the dispersant. The resultant
polymeri~ation product contains a carbonyl group with alpha-beta unsatura-
tion to a carbonyl group and at least one hydroxyl group.
Monomers which provide a carbonyl group with the alpha-beta
unsaturation and at least one hydroxyl group when reacted with an epoxide
are acryl;c and methacrylic acid. I~us, a polymer which is formed as
described herein using acrylic or methacrylic acid as monomer (iv) is
formed and then reacted with an epoxide. Suitable epoxides include styrene
oxide, glycidol, ethylene oxide, propylene oxide 1,2- and 2,3-butylene
oxide, butyl glycidyl ether, phenyl glycidyl ether and a glycidyl ester of
a saturated Cg_ll tertiary monocarboxylic acid. The reaction of the
acrylic or methacrylic units of the interpolymer with the epoxide results
in the formation on the polymer of a carbonyl group with the alpha-beta
unsaturation and at least one hydroxyl group.
A fifth component used in the formation of the polymer is a
compound capable of providing an amine or amine salt functional moiety.
This compotlnd is used at a leveJ rnnging ~rom about 0.1 percent to about
15 percent, preferably from about 0.5 percent to about 3 percent of the
polymer reaction mixture. The amine salt functional moiety can be
provided by an aliphatic or alicyclic amine which forms a salt with the
carboxyl moiety of the interpolymer compound. Examples thereof include
oleylamine, cyclohexylamine, dimethylbenzylamine, dimethylethanolamine,
diethylethanolamine and stearylamine. One source of amine functional
moieties is provided by an acrylic or methacrylic compound containing amino
groups, e.g., dimethylaminoethyl methacrylate, ethyl-, propyl- and t-boutyl-
aminoethyl acrylate and t-butylaminoethyl methacrylate or 2- and 4-vinyl
pyridine. Such compounds are polymerized into the backbone of the inter-
polymer. Additionally, the amine functional moiety can be provided by the
inclusion of a nitrogen~containing ring opening compound in the polymerization
reaction mixture. Such compounds are represented by the following formula:
IR2 I3 IR4
Rl - C - (C~ ~ C - Rs
N
R6
where Rl, R2, R4, Rs, and R6 are each hydrogen; alkyl having up to
20 carbon atoms, e.g., methyl, ethyl or propyl; aryl, e.g., phenyl;
alkaryl, e.g., tolyl or xylyl; or aralkyl, e.g., benzyl or phenethyl. R3
is hydrogen or a lower alkyl having from 1 to 6 carbon atoms and n is
O or 1. Examples of suitable compounds useful herein include: ethylenimine
(aziridine), 1,2-propylenimine, 1,3-propylenimine, 1,2~-dodecylenimine,
l,l-dimethyl ethylenimine, phenyl ethylenimine, benzyl ethylenimine, tolyl
1146694
ethylenimine, hydroxyethyl ethylenimine, aminoethyl ethylenimine, 2-methyl
propylcnimine, N-ethyl ethylenimine, N-phenyl ethylenimine and ~-tolyl
ethylenimine. The preferred aziridine compounds are the alkylenimines
havi~g 2 to 4 carbon atoms, especially ethylenimine and 1,2-propylenimine.
The polymers are made by conventional solution polymerization of
the aforedescribed individual components in an inert organic solvent. A so
called "one shot" procedure can be used wherein each of the individual
monomers is present at the start of the polymerization reaction. The
reaction i~ conducted at a temperature of from about 80C. to ab~ut
160C., preferably from about 120~C. to about 145C. for from about 45 -
minutes to about 6 hours, preferably about 90 minutes to about 2 1/2
houra. Example~ oE suitable inert organic ~olvent~ include the following:
eeher-type nlcohoLs, e.g., ethylene glycol monobutyl ether, ethylene glycol
monoethyl ether and propylene glycol monobutyl ether, ethanol, propanol,
i~opropanol and butanol. The polymerization is carried out in the presence
of a vinyl polymerization catalyst. Preferred catalysts are the azo
compounds, e.g., alpha, alpha'-azobis(i~obutyronitrile), tertiary butyl
perbenzoate, tertiary butyl pivalate, isopropyl percarbonate and benzoyl
peroxide. It should be recognized that the resultant reaction product
can be isolated or have a part of the solvent removed. Preferably,
however, the solvent is retained for convenience in later forming the
pigment dispersion and the coating composition containing same.
The resultant polymers have a weight average molecular weight
determined by gel permeation chromatography, using a polystyrene standard,
of from about l,OO0 to about lO,OOO, preferably from about 2,000 to about
6,000. A molecular weight below about l,OOO i9 to be avoided inasmuch as
the resultant polymer ie too bFIttle and wi11 not pooe-e~ the desired set
g _
.
... ~ , ,
6~4
of properties. Similarly, a molecular weight above about 10,000 indicates
formation of a product which does not possess the desired set of dispersing
properties or appropriate compatibility. ~s above discussed, the molecular
weight of the po]ymer is determined by gel permeation chromatography using
a polystyrene standard. Determination of molecular weights of polymers in
this manner is well known.
The mixture of monomers used to make the above-described dis-
persant can additionally consist essentially of a monomer selected from the
group consisting of alkyl esters of acrylic acid wherein the alkyl group
contains from 3 to 20 carbon atoms, alkyl esters of methacrylic acid
wherein the alkyl group contains from 9 to 20 carbon atoms and mixtures
thereof. The level of this monomer ranges from about 1 percent to about 30
percent, preferably from about 5 percent to about 20 percent of the reaction
mixture. The inclusion of this monomer is to maintain flexibility or aid
in compatibility when so desired.
Pigment Dispersion Compositions
~le aforedescribed dispersants permit the prior preparation
of dispersions of pigments or pigment mixtures which are subsequently used
in coating compositions. Each of the dispersions can be employed for
the direct pigmentation of coating compositions. The pigment dispersions
can be prepared at any convenient time and stored for future use.
The pigment dispersions of this invention consist essentially
of from about 1 percent to about 50 percent, preferably from about 3
percent to about 30 percent of the aforedescribed dispersant, from about 10
percent to about 90 percent, preferably about 15 percent to about 80
percent of a pigment and the balance a liquid carrier. Pigments useful
-- 10 --
6~
herein include those conventionalLy used ;n the coatings i~dustry. ~xamples
of suitable pigments include the iron oxides, lead chromates, silico-
chromate, stronium chromate, lead carbonate, lead sulfate, barium car-
bonate, china clay, calcium carbonate, aluminum silica, zinc oxide, zinc
sulfide, æirconium oxide, antimony oxide, titanium dioxide, chrome green,
chrome yellow, thio-indigo red, phthalo blue, phthalo green, cobalt blue,
cadmium yellow, cadmium red, toluidene red, graphite, carbon black, metallic
aluminum, and metallic æinc.
The solvents used in the pigment dispersions are conveniently
the solvents used in the reaction of the monomers to form the inter-
polymer. Ho~ever, other solvents can be added, such as xylene or mineral
spirits.
The pigment dispersions can contain other additives commonly
used in pigment dispersions, for example, plasticizers, wetting agents,
defoamers, diluents and fLow control agents.
Pigment dispersions are made by grinding or dispersing the
pigment into the dispersant. The grinding is usually accomplished by
the use of ball mills, sand mills, Cowles dissolvers, continuous attritors
and the like, until the pigment has been reduced to the desired size.
After grinding, the particle size of the pigment is in the range of about
10 microns or less.
Coating Composition
The pigment dispersions described above are added to coating
compositions either by the manufacturer and/or just prior to use by the
consumer as a tinting composition. The pigment dispersions are compatible
with a wide variety of fiim-forming resins and do not adversely affect the
-- 11 --
~66~flt
properties of a dried film made from the coating colllpositions. In particula~
films made ~rom the co~positions of this invention have good color develop-
ment and intercoat adhesion, i.e., have the ability to adhere ~o a previously
formed film. This latter feature is difficult to attain and represents an
especially important feature possessed by the compositions herein.
Useful coating compositions consis~ essentially of from about
25 percent to about 98 percent, preferably about 30 percent to about
80 percent of the film-formiDg resin, from about 1 percent to about
70 percent, preferably about 20 percent to about 60 percent of the pigment,
from about 1 percent to about 50 percent, preferably about 2 percent to
about 30 percent of the dispersant and the balance liquid carrier. Suitable
film-forming resins used in conjunction with the pigment dispersions are
described in the succeeding paragraphs. The film-forming resin can be an
epoxy, vinyl, alkyd, polyester, acrylic, aminoplast, phenolplast, cellulose
derivative, amide or urethane resin or mixtures thereof. Copolymers
derived from such resins are also useful herein.
The epoxide resins used as a film-forming resin in the coating
compositions are those compounds having a 1,2-epoxy group, i.e.,
-CH - CH-
present in the molecule. Polyepoxides contain more than one 1,2-epoxy
group per molecule. In general, the epoxide equivalent weight will range
from about 140 to about 4,000. These polyepoxides are saturated or unsat-
urated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic.
They can contain substituents such as halogen, hydroxyl and ether groups.
- 12 -
69~L
One usef~l class of polvepoxides compriqes the epoxy polyethers
obtained by reacting an epihalohydrin (such as epichlorohydrin or epibromo-
hyclrin) with a polyphenol in the presence of an alkali. Suitable poly-
phenols include resorcinol, catechol, hydroquinone, bis(4-hydroxyphenyl)-2,
2-propane, i.e.~ bisphenol A; bis(4-hydroxyphenyl)-1,1-isobutane;4,4-di- -
hydroxybenæophenone; bis(~-hydroxyphenyl)-l,l-ethane; bis(2-nydroxy-
naphenyl)-methane; and 1,5-hydroxynaphthalene. One very common polyepoxide
is a polyglycidyl ether of a polyphenol, such as bisphenol A.
Another class of epoxy resins are the polyglycidyl ethers of
polyhydric alcohols. These compounds may be derived from such polyhydric
alcohols as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-
propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol,
glycerol, trimethylolpropane, and bis(4-hydroxycyclohexyl)-2,2-propane.
Another slass of epoxide resins are the polyglycidyl esters of
polycarboxylic acids. These compounds are produced by the reaction of
epichlorohydrin or a similar epoxy compound with an aliphatic or aromatic
polycarboxylic acid such as oxalic acid, succinic acid, glutaric acid,
terephthalic acid, 2,6-naphthalene dicarboxylic acid and dimerized linoleic
acid.
Still another class of polyepoxides are derived from the epoxida-
tion of an olefinically unsaturated alicyclic compound. These polyepoxides
are non-phenolic and are obtained by epoxidation of alicyclic olefins, for
example, by oxygen and selected metal catalysts, by perbenzoic acid, by
acid-aldehyde monoperacetate or by peracetic acid. Among such polyepoxides
are the epoxy alicyclic ethers and esters well known in the art.
- 13 -
~1~66~
Useful polyepoxides also include those containin~ oxyalkylene
groups in the epoxy molecule. Such oxyalkylene groups have the general
formula:
__ _ ,
----- O tCH2-C ¦-------
m n
where R is hydrogen or alkyl, preferably a lower alkyl having from 1
to 6 carbon atoms, m is 1 to 4 and n is 2 to 50. Such groups are pendant
to the main molecular chain of the polyepoxide or are part of the main
chain itself. The proportion of oxyalkylene groups in the polyepox;de
depends upon many factors, including the chain length of the oxyalkylene
group, the nature of the epoxy and the degree of water solubility desired.
Another class of polyepoxides consists of the epoxy novolac
resins. These resins are obtained by reacting an epihalohydrin with
the condensation product of aldehyde and monohydric or polyhydric phenols.
A typical example is the reaction product of epichlorohydrin with a phenol-
formaldehyde condensate.
Any well-known curing reactant for the above-described epoxy
resins is normally included in the coating composition. It is well
known chemicals and resins containing functional groups with active
hydrogen groups are useful as curing agents for the epoxy resins. Generally,
the curing agents cause polymerization by cross-linking of the epoxy
molecules. Amine and polyamide catalysts are especially preferred curing
agents.
- 14 -
~6~9~
Vinyl resins used in the coating compositions are derived rom
monomers containing a carbon to carbon double bond. These monnmers polymerize
by linear addition to form long chain molecules. Generally, the polymeric
resins have the structure:
rH R H R ~ R--
-- C -- C -- C -- C -- C -- C --
I I I I I I
H Rl H Rl H Rl n
where R and Rl represent various pendant groups such as hydrogen, chlorine,
acetate, benzene and toluene. The vinyl resins are commcnly derived from
the monomers vinyl chloride, vinylidene chloride, vinyl acetate, the vinyl
acetals, styrene, acrylonitrile and mixtures thereof. The vinyl polymers
and copolymers range from about 100 to 10,000 carbon atoms in chain length
and can be formed by bulk, solvent, suspension or emulsion polymerization.
Copolymers derived from mixtures of any of the aforedescribed
vinyl monomers either with themselves or with other commonly used polymer-
izable monomers are used herein. Such copolymers possess a wide range of
properties and can be formulated to fit individual needs.
One class of resins especially useful herein are the alkyd
resins. Such resins are polyesters of polyhydroxyl alcohols and poly-
carboxyl acids chemically combined with various drying, semi-drying
and non-drying oils in different proportions. Thus, for example, the
alkyd resins are made from polycarboxylic acids such as phthalic acid,
maleic acid, fumaric acid, isophthalic acid, succinic acid, adipic acid,
azelaic acid, sebacic acid as well as from anhydrides of such acids, where
~466~A~
they exist. The polyhydric alcohols which are reacted with the polycar-
boxylic acid include glycerol, trimethyloLethane, trimethylolpropane,
pentaerythritol, sorbitol, mannitol, ethylene glycol, diethylene glycol and
2,3-butylene glycol.
The alkyd resins are produced by reacting the polycarboxylic
acid and the polyhydric alcohol together with a drying, semi-drying
or non-drying oil in proportions depending upon the properties desired.
The oils are coupled into the resin molecule by esterification during
the manufacturing and become an integral part of the polymer. The oil
is fully saturated or predominately unsaturated. The fully saturated
oils tend to give a plasticizing effect to the alkyd, whereas the pre-
dominately unsaturated oils tend to cross-link and dry rapidly with
oxidation to give more tough and durable alkyd resins. Suitable oils
include coconut oil, fish oil, linseed oil, tung oil, castor oil,
cottonseed oil, safflower oil, soybean oil, and tall oil. Various pro-
portions of the polycarboxylic acid, polyhydric alcohol and oil are
used to obtain alkyd resins of various properties.
Also useful herein are polyester type resins. As convention-
ally used and as used herein, the term "polyester" is applied to resins
which contain no oil or fatty acid modification. That is, while the
above-described alkyd resins are in the broadest sense polyester type
resins, they are oil-modified and thus not generally considered a polyester
resin. The polyesters are of two kinds. The more common are the unsatur-
ated polyesters derived from unsaturated polyfunctional acids and polyhydric
alcohol. These polyesters are essentially linear in structure. Male;c
acid and fumaric acid are the usual unsaturated acid componen.s. Co~monly
used polyhydric alcohols are ethylene glycol, propylene glycol, diethylene
~ 16 -
6~94
glycol, dipropylene glycol, butylene glycoll glycerol, trimethylol propar~e,
pentaerythritol and sorbitol. Oftentimes a saturated acid will be included
in the reaction to provide desirable properties. Examples of saturated
acids include phthalic acid, isophthalic acid, adipic acid, azelaic acid,
sebacic acid and the anhydrides thereof where they exist. The saturated
polyesters are derived from saturated or aromatic polyfunctional acids,
preferably dicarboxylic acids, and mixtures of polyhydric alcohols having
an average hydroxyl functionality greater than 2.
Useful acrylic resins are the polymerized ester derivatives
of acrylic acid and methacrylic acid. The resins contain the units
fH3
(-CH2 - CH-)n and (-CH2 - C-)n
0=C-0-R O=C-0-R
respectively. The esters are formed by the reaction of acrylic or meth-
acrylic acid with suitable alcohols, e.g., methyl alcohol, ethyl alcohol,
propyl alcohol, butyl alcohol and 2-ethylhexyl alcohol. Generally speaking,
the larger the alcohol portion of the ester, the softer and more flexible
the resultant resin. Also, generally speaking, the methacrylate esters
form harder films than the corresponding acrylic esters. Monomers such as
styrene, vinyl toluene, vinyl chloride and vinylidine chloride may be
reacted with the acrylic and methacrylic esters so as to produce resins
with excellent properties.
Thermosetting acrylic resins are normally low molecular weight
copolymers made from 2 and sometimes 3 monomers. One of the monomers is an
acrylic compound containing pendant reactive groups such as carboxyl,
~6~
hydroxyl or amide. Another i9 an acrylic ester. The third monomer is
usually a .styrene type monomer such as styrene itself, vinyl toluene,
methyl styrene or ethyl styrene. The proportions of the three co-nponents
in the polymerization procedure are varied depending on the products in
which the copolymer will be used.
Another class oE film-forming resins useful in the coating
compositions herein is the amino resins commonly referred to as aminoplasts.
The amino resins are made by the reaction of an amine with an aldehyde.
The more important and preferred amines are urea and melamine. The aldehyde
component comprises from 1 to 4 carbon atoms, with formaldehyde being the
preferred aldehyde. Films of varying properties can be obtained by changing
the proportions of the amine and aldehyde and by adding various chemically-
reactive materials during the resin formation. Oftentimes, a lower alcohol,
especially butanol, is added during the resin formation to impart desirable
properties to the amino resin.
The phenolic resins commonly referred to as phenoplasts are
also useful film-formers in the context of the subject invention. The
phenolic resins are obtained by the condensation of phenol or substi-
tuted phenols with aldehydes. The monohydric phenols such as phenol,
cresol and xylanol are the most important since they are readily available
and relatively ine~pensive. Phenol is the most preferred monohydric
phenol. Polyhydric phenols such as resorcinol can also be used herein.
Formaldehyde is the preferred aldehyde used in the production of the
phenolic resins. Other aldehydes which are also useful include acetaldehyde,
butyraldehyde and furfuraldehyde. The preferred phenolic resin is produced
by the condensation of phenol and formaldehyde.
- 18 -
~6~
Different celluLose derivative~s useful herein incLude nitro-
ceLLulose, cellulose acetate, cellulose acetate butyrate and ethyl cellulose.
These film-~ormîng materials are well known and are commercially ava;lable
in varying degrees of substitution and molecular weight. Nitrocellulose is
the preferred cellulose derivative.
Amide resins found to be useful include those polymers made
by condensing a diamine with a dibasic acid. They are characterized
by recurring amide groups, -CONH-, as an integral part of the main polymer
chain. Examples of diamines used in producing the polyamide resins include
ethylenediamine, diethylenetriamine and hexamethylenediamine. The carboxylic
acids are the preferred dibasic acids and include adipic acid, sebacic
acid, succinic acid, glutaric acid and azelaic acid.
Another class of film-formers used in the invention herein
are the urethane resins. These are synthetic polymers that may be either
thermoplastic or thermosetting. The basic polymeric unit is RNHCOOR. The
R groups can be the same or diEferent and can contain other reactive
groups, for example, a second -NCO group, a second -OH group, etc. Typi-
cally, a polyhydric alcohol is reacted ~ith a polyisocyanate to produce the
urethane resin. Useful polyhydric alcohols include ethylene glycol,
propylene glycol, butylene glycol, glycerol~ trimethylolpropane and hexane
triol. Many variations are possible.
The urethane coating can be made from a one-pack or two-pack
system. The one-pack urethane contains either an isocyanate prepoly-
mer or a blocked ;socyanate. The prepolymers are prepared by the re-
action of excess diisocyanate with a polyhydric alcohol. Blocked iso- -
cyanates contain no free isocyanate groups and are relatively inactive
- 19 -
11~66~
at room temperature. At elevated temperatures, the compounds dissociflte and
undergo reactions typical of isocyanates. Typical blocking agents are
phenols, thiols, tertiary alcohols and secondary aromatic amines. In a
two-pack coating system, typically a polyester polyol and an isocyanate (or
isocyanate prepolymer for safety reasons) are mixed at the time of appli- -
cation and applied immediately.
It will be recognized that a grea~ many copolymers based
upon the above~described monomers are possible. Such copolymers possess a
wide range of properties and can be formulated to fit individual needs.
The copolymers are contemplated herein as being ùseful film-forming resins
compatible with the resin dispersants of this invention.
The balance of the compositions comprises a liquid carrier
material. Many different organic solvents are suitable, examples of which
include hydrocarbons and halogenated hydrocarbons such as toluene, xylene,
mineral spirits, n-hexane, cyclohexane, chlorobenzene, and perchloroethylene.
Additives commonly used in coating compositions can be used
herein also. Such additives include plasticizers, fillers, surfactants
and stabilizers.
The coating compositions are applied by conventional coating
techniques onto a variety of substrates. Thus, the compositions can
be applied by spraying, brushing, dipping, flow coating and roll coat-
ing. Substrates that can be coated include wood, metals, glass, plastics
and wallboard.
The examples which follow are illustrative of the invention.
All molecular weights given are determined by gel permeation chromatography
using a polystyrene standard.
- 20
~L4~
EXAMPLI~ I
Isobutyl methacrylate ]117 grams
Methyl methacrylate 466.5 grams
Acrylic acid 42.1 grams
Dimethyloctadecylamine 37.2 grams
~Iydroxyethyl acrylate 42.1 grams
2-Mercaptoethanol 25 grams
Tertiary butyl perbenzoate (TBPB) 116.8 grams
~thylene glycol monobutyl ether 1525.7 grams
Denatured ethyl alcohol 30 grams
A reaction vessel is set up equipped with heating means, stirring
means, means for maintaining a nitrogen blanket throughout the reaction and
refluxing means. ~ solvent blend of 1346 grams ethylene glycol monobutyl
ether and the denatured alcohol is heated to reflux under a nitrogen
blanket. At the reflux temperature a stream of the isobutyl methacrylate,
methyl methacrylate, hydroxyethyl acrylate, acrylic acid and 2-mercapto-
ethanol and ~mother stream of 83.4 grams of TBPB and 118 grams of ethylene
glycol monobutyl ether are added to the reaction mixture over a period of
two hours. This mixture is held at reflux for one hour after .he separate
streams have been charged to the reaction vessel. Thereafter, the reaction
is cooled to 120C. at which time 33.4 grams of TBPB and 61.7 grams of
ethylene glycol monobutyl ether are added over a period of one hour.
This mixture is then held one hour at 120C. The resultant reaction
mixture contains 50 percent solids and has a Gardner-~oldt viscosity of
H-I. The amine functional salt of the resin dispersant is formed by adding
the dimethyloctadecyl amine to the reaction mixture.
The dispersant has a weight average molecular weight of 2200.
1~4ti6~4
_~MP~E II
The following components are utili~ed in forming a resin dispersant:
Isobutyl methacrylate1278.9 grams
Methyl methacrylate 302.9 gram~
Methacrylic acid 42.1 grams
Hydroxyethyl acrylate 42.1 grams
Dimethylaminoethyl methacrylate 16.8 grams
2-Mercaptoethanol 50.5 grams
Ethylene glycol monobutyl ether 1573.3 grams
Denatured ethyl alcohol33.7 grams
Tertiary butyl perbenzoate (TBPB) 84.1 grams
A reaction vessel is set up equipped with heating means,
stirring means, means for maintaining a nitrogen blanket throughout
the reaction and refluxing means. A solvent blend of 1346.1 grams of
the ethylene glycol monobutyl ether and the denatured ethyl alcohol is
heated to reflux under a nitrogen blanket. At the reflux temperature
a stream of the methacrylic acid, hydroxyethyl acrylate, isobutyl meth-
acrylate, methyl methacrylate, dimethylaminoethyl methacrylate, 2-mercapto-
ethanol and 50.5 grams of ethylene glycol monobutyl ether and another
separate stream of 75.7 grams of the TBPB and 75.7 grams of the ethylene
g]ycol monobutyl ether are added to the reaction mixture over a period of
two hours. This mixture is held at reflux for one hour after the separate
streams have been charged to the reaction vessel. Thereafter, the reaction
is cooled to 120C~ at which time 8.4 grams of TBPB and 176.7 grams of
ethylene glycol monobutyl ether are added over a period of one hour. This
mixture is then held for one hour at 120C.
- 22 -
~46694
The resultant mixture has a solid3 content o~ 49.6 percent and a
Gardner-l~oldt viscosity of R-F. The ~ispersant has a molecular weight of
llQO.
EXAMPLE III
A reaction vessel is equipped as in Example I. The following
components are used in the reaction:
Isobutyl methacrylate 1100.0 grams
Methyl methacrylate466.5 grams
Acrylic acid 42.1 grams
Hydroxyethyl acrylate 42.1 grams
Dimethylaminoethyl methacrylate 16.7 grams
2-Mercaptoethanol 16.7 grams
~A Propasol B 1521.1 grams
Denatured ethyl alcohol 30.0 grams
Ethyl alcohol 72.9 grams
Tertiary butyl perbenzoate (TBPB) 84.1 grams
Propasol B is an isomeric mixture of n-butoxy propanol available
from the Union Carbide Corp.
The reaction vessel is initially charged with 1346.1 grams of
Propasol B and the denatured ethyl alcohol. This solvent mixture is
heated to reflux, i.e., about 145C. Thereafter over the next two hours,
separate streams of (1) the acrylic acid, hydroxyethyl acrylate, isobutyl
methacrylate, methyl methacrylate, dimethylaminoethyl methacrylate, 2-
mercaptoethanol and 50.5 grams of the Propasol B and (2) 75.7 grams of the
TBPB and 75.7 grams Propasol B are added. The temperature is adjusted to
120C. with the ethyl alcohol. Over the next one hour, 8.4 grams of TBPB
~i~ Tr~e ~rk
- 23 -
:,
6f;S~
and 103.8 grams of Propasol B are added. lhis mixture i9 then held for one
hour anci cooled.
The reaction mixture is comprised of 49.5 percent solids and has
a Gardner-~oldt viscosity of K-L. The dispersant has a molecular weight of
2200.
EXAMPLE IV
The following components are used to produce a resin dispersant:
Isobutyl methacrylate1278.9 grams
Methyl methacrylate302.~ grams
Methacrylic acid58.9 grams
Hydroxyethyl acrylate42.1 grams
2-Mercaptoethanol50.5 grams
Ethylene glycol monobutyl ether 1648.0 grams
Tertiary butyl perbenzoate ~TBPB) 84.1 grams
Propylenimine lO.ô grams
Denatured ethyl alcohol33.7 grams
A reaction vessel is set Up as in Example I. Initially, 1346.1
grams of ethylene glycol monobutyl ether and 33.7 grams of the denatured
ethyl alcohol are charged to the reaction vessel and heated to 144C.
Thereafter separate streams of (1) the methacrylic acid, hydroxyethyl
acrylate, methyl methacrylate, 2-mercaptoethanol and 50.5 grams of the
ethylene glycol monobutyl ether and of (2) 75.7 grams of TBPB and 75.7
grams of the ethylene glycol monobutyl ether are added to the reaction
vessel. The temperature during this addition is maintained at 140C. with
the addition made over a period of about 2 hours. The mixture is cooled to
120C. with ethanol and 177 grams of ethylene glycol monobutyl ether and
~ 2~ -
11~6~i~4
8.4 grams of TI~PB are added over one hour. Ihe reaction is cooled to 55C.
and when this temperature is reached, the propylenimine i8 added and the
reaction mixture held at 65-70C. for a time period of two hours.
The reaction mixture is analy~ed and found to contain 50.9
percent solids. It has a Gardner-Holdt viscosity of G-~. The dispersant's
weight average molecular weight is 2600.
EXAMPLE V
A resin dispersant is made following the procedure of Example IV
except acrylic acid is used in place of the methacrylic acid, 1100.0 grams
of the isobutyl methacrylate is used instead of the 1278.9 grams and
471.2 grams of the methyl methacrylate is used instead of the 302.9 grams.
The final reaction mixture contains 50 percent solids. The dispersant's
weight average molecular weight is 3000.
~XAMPL~ VI
A resin dispersant is made following the procedure of Example III
except 933.7 grams of 2-ethylhexyl methacrylate is used in place of the
isobutyl methacrylate and 633.6 grams, instead of 466.5 grams, of methyl
methacrylate is used. The dispersant's weight average molecular weight is
4600.
EXA~PLE VII
Example III is repeated except butyl methacrylate is used
in place of the isobutyl methacrylate, at the same level. The resultant
solution containing the resin dispersant has a solids content of 49.6
percent. The weight average molecular weight of the dispersant is 5600
- 25 -
~1~6~94
EXAMPLE VIII
Another res;n dispersant :i9 made following the procedure of
Example IV except 1083.8 grams butyl methacrylate is used in place of the
isobutyl methacrylate, 466.5 grams methyl methacrylates is used and 55.8
grams of acrylic acid is used in place of the methacrylic acid. The
dispersant's weight average molecular weight is 5800.
EX~PLE IX
A resin dispersant using butyl methacrylate and styrene in
place of isobutyl methacrylate and methyl methacrylate, respectively,
and at equal levels is made using the procedure described in Example ~ -
III. The resultant d;spersant's weight average molecular weight is 5600.
EXAMPLE X
The dispersant of Example III is used to formulate pigment
dispersions having the following compositions:
Pigment Percent Dispersant Percent Solvent Percent
Black tint (1) 20 16 64
White tint (2) 74 5.2 20.8
Yellow tint (3) 55 9 36
Red tint (4) 68 6.4 2506
Blue tint ~5) 20 16 64
Green tint (6) 18 16.4 65.6
(1) The pigment is a #6 Lamp Black available from General Carbon Co.
(2) The pigment is Titantium Dioxide R 960 available from E. I. Dupont
De Nemours & Co., Inc.
(3) The pigment is Yellow Iron Oxide 1888D available from Pfizer Inc.
(4) The pigment is Red Iron Oxide R-3098 available from Pfizer Inc.
~c rr~de mc~t k
- 26 -
(5) The pi~ment is Phthalo Blue BT 42SD available from E. I. Dupont
~e ~emours & Co., Inc.
(6) The pigment is Phthalo Green ~T 751D available from E. I. Dupont
De Nemours & Co., Inc.
The solvent is an isomeric mixture of n-butoxy propanol available
from Union Carbide Corp. as Propasol B.
The p;~ent dispersions are made by first premixing the pig-
ment, dispersant and solvent on a Cowles mixer for about 20 minutes to
form a well wetted uniform mix. Next, the premix is gro~nd on a Sussmeyer
mill until the resultant paste possesses a Hegmann ~rind Gauge reading of
+7. Optionally, a portion of the dispersant and solvent is held back from
the initial premixing step and is used to wash down the Sussmeyer mill.
The wash is added to ~he previously milled paste to form pastes having the
above compositions.
EXAMPLE XI
The pigment dispersion of this invention is tested for tint
compatibility with paints containing different film-forming resins as
described below. The pigment dispersion used in this example is the
black tint pigment dispersion of Example X.
Percent Percent Volatile
Film-Forming Percent Pigment Carriers, Flow
Resin Type Film-Former Dispersion Control Agents, etc.
(A) 80 percent tall oil 37.2 6.2 Balance
~atty acid alkyd
resin cross-linked
with 20 percent
aminoplast (l)
(B) Acrylic resin ~2) 32.5 5.4
(C) Vinyl toluene alkyd 24.8 4.1 "
copolymer (3)
~ ' ~ r~e ~
6~'~
(D) Acrylic/epoxy co- 20.7 3.5 "
polymer (4).
(~) Plasticized acrylic 22.4 3.7 "
lacquer (5)
(F) Vinyl resin (6) 28.2 4.7 ~ _
(G) Medium oil alkyd 30.4 5.1
resin (7)
(H) Acrylic/melamine 29.7 4.9 "
copolymer (8)
(I) Nitrocellulose/ 16.7 2.8 "
alkyd lacquer (9)
(1) The aminoplast is available from Monsanto Co. as Resimine 735.
(2) The acrylic resin is an internally cross-linked acrylic resin found in
PPG Industries, Inc. DURACRON ~ 00.
(3) A vinyl toluated alkyd resin.
(4) A 90:10 blend~ of an internally cross-linked acrylic resin of Example
~j and EP~)N~1001~ available from Shell Chemical Co.
~5) An air dry lacquer acrylic resin having imine modification made by
PPG Industries, Inc.
(6) A resin blend of 78 percent of a solution vinyl resin and 22 percent of
a chlorinated paraffin.
(7) Derived from 59 percent soya oil, 29 percent phthalic anhydride
and 12 percent pentaerythritol.
(8) A hydroxy functional acrylic resin cross-linked with an aminoplast.
(9) A 35/65 blend of a nitrocellulose solution and tall oil fatty acid
glycerol alkyd resin.
Compatibility of the pigment dispersions with the film-forming
resins in the respective paints and their effect on the properties of a
formed film are determined using a series of tests. Initially, the paints
are shaken for 10 to 15 minutes and allowed to digest overnight. Then 1.0
to 1.2 mil (dry) films of the paints on steel panels are formed by spraying.
~ r~ v~
- 28 -
i69~
Compatibility is determinecl by a rub-up test. Wh;le the films on
the above-described steel panels are still wet, they are rubbed with the
forefinger. Any lighten;ng of the color is noted. A noticeable change
in color between the rubbed portion of the wet film and the unrubbed
portion is an indication of incompatibility of the pigment dispersions in
the paint. The following rub-up values are obtained based on a 0 to 10
scale with 0 being no change in color and 5 being the value above which a
significant color change and hence a compatibiLity problem is experienced.
Paint Rub-up
(A) 3
(B)
(C)
(D) 3
(E) 2
(F) 2
(G) 2
(H)
(I) 1
The above results show that the pigment dispersion of this
invention is compatible with a wide variety of film-forming resins.
The effect the pigment dispersions have on the properties of
the formed films is determined using a (1) direct and reverse impact
test, (2) pencil hardness test, and (3) intercoat adhesion test. The
impact tests are conducted using a Gardner Variable Impact Tester. The
pencil hardness test is a measure of the film's hardness. A hardness
value is assigned a film based on its ability to withstand pressure
applied by a pencil having a specified grade of lead. The intercoat
- 29 -
11~6694
adhesion test measures the ability of the forme(l ~ilm to adhere to a
previously coated substrate.
In all instances, coating compositions (A)-(I) have substantially
equivalent or better properties than controls where the above described
pigment dispersions are omitted.
EX~MP~E XII
Resin dispersants made from the compounds indicated in the
chart (expressed as percents) are tested for compatibility and their
effect on film properties of a paint containing them. Resin dispersants
A, B, C, D, E, F and G correspond with the dispersants of Examples III, V,
I, VI, VII, VIII and IX, respectively.
Resin dispersant A B C D E F G
Isobutyl methacrylate6666 66 - - - -
2-Ethylhexyl methacrylate - - - 56
Butyl methacrylate - - - - 66 65.5 66
Methyl methacrylate 28 28 27 38 28 28
Styrene - - - - - - 28
Acrylic acid 2.52.52.5 2.52.5 2.5 2.5
Hydroxyethyl acrylate2.52.52.52.5 2.5 2.5 2.5
Amino functional moiety(l)
Amino functionai moiety(2) - 1 - - - 1.5
Amino functional moietyt3) ~ ~ 2
(1) The amino functional moiety is provided by polymerizing dimethyl-
aminoethyl methacrylate into the resin dispersant's polymeric backbone.
(2) The amino functional moiety is provided by an aziridine ring opening
reaction.
(3) An amine salt of the resin dispersant is formed from the dispersant and dimethyloctodecyl amine.
-- 30 --
6~4
The above resin dispersants are tested by ndding them nt a 6
percent level to (1) an internally cross-linked acrylic resin based paint
and (2) an alkyd/melamine based paint. Values for color development,
rub-up and intercoat adhesion are obtained. The color development value is
a measure of the resin dispersant's efficiency as determined by its ability
to even]y disperse pigment throughout the dried film. A value of 1 is
excellent, 10 poor and 5 marginally acceptable.
Cross-Linked Acrylic Resin Based Paint
Resin Dispersant Color Development Rub-Up Adhesion
A 4 3 o.k.
B 4 2 o.k.
C 3 2 o.k.
D 2 1 o.k.
E 2 2 o.k.
F 2 3 o.k.
G 2 1 o.k.
Alkyd/~elamine Resin Based Paiut
Resin Dispersant Color Development Rub-Up Adhesion
A 1 3 o.k.
B 3 3 o.k.
C 2 3 o.k.
D 2 3 - o.k~
E 2 3 o.k.
F 2 3 o.k.
G 2 3 o.k.
- 31 -
6~fl~
Ihe above results show the resin dispersants of this inven-
t;on perform satisfactor;ly as pigmen~ dispersa~t3, are compatible with
the tested coating composition and do not have an adverse effect on the
formed film's intercoat adhesion.
