Note: Descriptions are shown in the official language in which they were submitted.
"` ~2~ 3~
TITLE
ISOCYANATE ADDUCT DISPERSANTS
FOR PIGMENTED COATING COMPOSITIONS
BACKGROUND OF THE INVENTION
1. Field of the Invention
.. . . _
This invention relates to novel compounds
useful as dispersants in coating compositions.
2. Prior Art
Plke U.S. Patent 2,662,027 shows aluminum
flake in paints and discusses "two-tone" finishes.
Simms U.S. Patent 4,219,632 and Brixius and
Simms U.S. Patent 4,222,909 show isocyanato~alkyl
acrylate and methacrylate polymers of controlled low
molecular weight-
Thompson U.S. Patent 3,788,996 showscoating compositions with film-forming polymers
containing known dispersants.
BRIEF DESCRIPTION OF THE INVENTION
The novel compounds of this invention are
of the type sometimes called "AB" dispersants. Such
dispersants have the general formula A-Z-B where Z
is an organic linking radical, usually monomeric,
and A and B are substituents having different
polarities but attached to the same radical. Thus,
A can be hydrophobic radical such as that of a fatty
amine. It is then compatible with fat or grease
which may be present on aluminum flake or other
inorganic pigment. At the same time, B can be a
hydrophilic radical containing, for example, a
hydroxyl group or even, in this case, a lower alkyl
amine and hence compatible with a film-forming
polymer used as a dispersing medium. The dispersing
agent thus aids in the dispersal of the pigment by
helping maintain it in dispersion.
. ~
;~lA2G~231
The formula for the compounds of t~is inven-
tion, prepared by the direct interaction of the
precursors, may be written as
~A]a ~ I rB]b
~C]c
where Z is an organic linking radical resulting from the
reaction of a polyisocyanate, generally polymeric, with
amines as defined below yielding the moieties A and B
and, optionally,Cin the ratios a, b and c.
DETAILED D~S'CRIPTION OF THE INVENTION
As noted, the organic linking radical Z in
AB dispersants of the 'formula given above is generally
monomexic, Here,' however, it is generall~ polymeric,
res'ultins, in ~act, from the 'reaction of a polymerized
ester of an isocyanatoalkyl acryltc or methacrylic acid
having at least 10-25~ by weight of Isocyanate monomer
and a number average molecular wei'ght Mn of 500-10,000
with an amine as defined hereinafter through a urea
linkage of the formula
o
where Rl and R2 are alkyl radicals.
The polymeric isocyanate esters from which Z
is derived may be any of those of the Brixius et al and
Simms references noted above. They may be either homo-
polymers, i.e., of the isocyanatoalkyl!esters alone, or
copolymers of the esters with one or mqre other ethyleni-
cally unsaturated monomers. The Brixius et al polymers
contain sulfide end groups. The preferred isocyanate
ester is isocyanatoethyl methacrylate tIEM).
Any comonomer polymerized with the isocyanate
ester in æ is preferably at least one of the group con-
sisting of alkyl acrylates or methacrylates having up to
~2' al~23~
12 atoms in the alkyl group, styrene, ethylene, and vinyl
esters such as vinyl acetate and vinyl chloride. More
than one of these comonomers may be used together, if
desired. Butyl acrylate and styrene are preferred co-
monomers and may be employed simultaneously.
While polymeric isocyanate residues are pre-
ferred for the purpose o this invention, it is not
restricted thereto. Thus, Z can represent any of the
monomeric di-, tri-, etc., polyisocyanates shown by the
Thompson patent cited. It is understood, of course, that
when the optional component C of the formula is
employed, the isocyanate is at least a triisocyanate.
A in the formula is here the amine moiety
which results from the reaction of the amine group of a
fatty acid amine with isocyanate groups initially on the
linking radical Z. ~he fatty acid amines are the ali-
phatic amines with aliphatic ~roups having between 12 and
24 carbons. The higher amines are preferred, e.y., those
having between 16 and 24 carbons in the aliphatic groups.
These fatty acid amines are available commercially under the
trade mark Ke~amines sold by the Humko Sheffield Corporation
and described in their literature. Primary amines are pre-
ferred but secondary amines can be used. Kemamine P-997
D, distilled soya amine, 97% primary, is preferred.
26 B in the formula is the am~ne moiety
which results from reaction of the amine group of a
lower primary or secondary amine (having up to 6 carbons
in the alkyl groups) or of an alkanolamine of up to 6 car-
bons in the alkanol groups with isocyanate groups
originally on Z. Preferred such compounds are butyl-
amines and ethanolamines. Mixtures of various E radicals
can be used, if desired, but to no particular purpose.
C in the formula is the optional, but
sometimes desirable, amine moiety which results from
31
reaction of the amine'group of a primary or sec'ondary
amlnosilane of the 'formula
HnN- [ (CH2 ) p-Si (Y~]m
whereln Y is alkyl of up to 6 carbons, m and n are 1 or
2 and the sum of m and n is 3,' and p is 6.
All the'isocyanate groups of the linklng radi-
cal ~hould be replaced to insure stability of the prod-
uct. Consequently, the'subscripts a, b and c should
total the value 100, representing the mole percentage
of isocyanate replaced. For the purposes o this inven-
tion, a can vary between 20 and 80 and b can vary
between 80 and 20~ The aminosilane is optional, and c
can ~ary between 0 and 40.
It will be appreciatea that, while the moiety
Z in the present compounds is associated with specific
moieties A, B and C, it need not be so associated. Thus,
it can replace the'monomeric polyisocyanates shown by -
Thompson as forming the linking radical in dispersants.
In fact, it can replace these monomeric materials gen-
erally in dispersants carrying substituents of differing
solubility.
The compounds of the formula above can be pre-
pared very simply by the direct add~tion o~ the calcu-
lated amounts of the reactants. The 'reaction is exo-
thermic, however, and reactants should be cooled.
Preferably, therefore, the isocyanate-bearing polymer
(or other polyisocyanate) is dissolved in a suitable
organic solvent such as methyl ethyl ketone and N-methyl-
pyrrolidone and cooled with ice to 5-10C. A mixture of
the other reactants is added and the reaction allowed to
proceed to completion with stirring, e.g.~ in about an
hour. The coreactant amines can be added separately to
the isocyanate in calculated amount but nothing is gained
by such procedure.
~2 13l3;~31
The compounds of this invention are solids or
li~uids~ very soluble in organic solvents and, as noted,
they tend to stabilize dispersions of inorganic materials
in organic soivents. They are particularly useful as
dispersants in dispersions containing metal flake or in-
organic pigment. They ma~ also be used with dispersIons
of magnetic ox~des such as iron or chromium oxldes in
organic liquid for magnetic tapes.
Dispersions using the novel compound may be
otherwise conventional coat~ng compositions containing
pigments. Such compositions are described, for example,
in the Thompson patent clted. Thus, polyvinyl chloride,
polyvinyl fluoride, etc., compositions can be used. Pre-
ferred, however~ as with Thompson, are acrylic composi-
tions containin~ polymers and copolymers of acrylic andmethacrylic acids. The acryl-~c coating compositions of
the Khanna and Turner~ U, 5, Patent 4,276,216 based
on acrylate polymers bearing hy~r~xyl groups and cured
with alkylated melamine formaldehyde cross~linking
20 agents are also usable with the present novel
dispersants.
The pigment employed can be any of the inorganic
materials commonly used as pigments (including carbon~.
Preferrs~d is aluminum flake, admixed with hydrocarbon and
~nitially in the form of a paste. The hydrocarbon on the
surface of the flake provides a coating compatible with
the hydrophobic radical A of the dispersants.
The amount of dispersant used in the coating
composition depends upon the amount of inorganic pigment
present. About 5% by weigh~ based on the weight of the
pigment is employed although 1-10% can be used (see Ex-
ample 3, below). Generally the dispersant is mixed with
the pigment b~fore the latter is dispersed but it can be
added separately, if desixed.
Z31
When employed in paints or enameIs, dispersants
improve the gloss of coatings as described by the term
"two-tone" or its synonym "metalllc glamour". Metallic
glamour can be objectiveIy measurea with a special
goniophotometer using the following geometrical arrange-
ment. A coated test panel is positioned hbrizontally
within the goniophotometer ~ith the coated sIde facing
up. The light from a circular, concentr~ted light source
is collimated by a lens and is directed to strike the
panel at a small angle, typically 22.5, from the normal.
The light beam reflected from the surface o~ the panel
is directed by a second lens, at unity magnification,
through a circular aperture having approximately the same
diameter as ~he light source. A photocell is positioned
at a distance of about 6-10 aperture diame~ers behind the
aperture and is of sufficient size to intercept all light
reflected from the paneI through the aperture. The panel
can be rotated to different viewing angles about an axis
that is defined as the intersection of the plane of the
panel and the plane defined by the beam of light inci-
dent to and reflected from the panel in its original
horizontal position. It has been found particularly use-
ful to measure the intensity of the reflected light at
two different paneI positions, when the panel has been
rotated to positions of ~10 and +60 from its initial
horizontal position.
The goniophotometer gives unitless numerical
readings known as luminous reflectance (G) for each angle
from which the panel is viewed. The photocell is cali-
brated, with respect to the light source, to indicate aluminous reflectance of 100 for a nonmetallic, matte-
surfaced, perfect white viewed at any angle setting.
Nonmetallic coatings give equivalent reflectance readings
from any angle of view.
V82~.
In a coating having good metallic glamour, the
reflectance measured at 10 will be greater than that
measured at 60. The reflectance at a given angle A is
related to another visual characterlstic known as light-
ness (L) through the equation
L(A ~ = 25.29G(A) - 18.83
Goniophotometry, reflectance, and lightness are generally
expla~ned in The ~easurement of Appearance, Hunter, R.S~,
John Wiley and Sons, New York (1975).
An objective characterization of the metallic
glamour, the flake orientation index (F.O.I.~, is in turn
expressed as a function of the lightness of the coating
at 10 or 60. The mathematical expression is:
F.O.I. = 10 aL/~L(lOD) + L(60~
where ~L - L(10) - L(60). The denominator of this -
expression is a normalizing term empirically determined
to produce equal F.O.I. values for all coatings having
the same metallic glamour, regardless of the color of the
coating. It accounts for the color intensity of the coat- -
ing and the ability of the coating to hide the substrate,
both dependent on the amount of chromatic pigment. An
index (I or F.O.I.) of at least 40, preferably ~5, is
desirable.
EXAMPLES
There follow some Examples illustrating this
invention together with a preliminary Comparative Example.
These differ primarily in that the latter does not employ
the dispersant of the invention. In all Examples, ratios,
proportions, parts and percentages are in terms of weight
and temperatures are in degrees centigrade unless other-
wise noted. The dispersants of the invention were tested
in acrylate coating compositions of the type shown in
the above-~entioned patent of Khanna and Turner.
Z31
The ~ollowing polymers,, which form no part of
the in~ention, were employed in the examples:
Polymer I. This was the' polymer methyl methacrylate/
butyl acrylate/2-hydroxyethyl acrylate 1n the proportions
30~38~32~ Mn = ca. 3~000; Solids = 83~ in methyl ethyl
ketone (MEK~. It may be prepared, ~or exampie, as shown
in Example 3 o~ Khanna and Turner.
Polymer II. ThIs was an isocyanate-containing poly-
mer of the composition methyl methacrylate~butyl acry-
late/IEM/lauryl mercaptan residue/azobis(isobutyronitrile~residue in the proportions 56.7/9.6~28.4/2.1~1.6, prepared,
e.g., as in Example 1 of the above-identified Brixius
and Simms patent: -~CO = 7.5% on solids; Mn =
ca. 2,200.
Polymer IXI. This was an isocyanate-containing poly-
mer of the composition IEM~styrene/butyl acrylate/lauryl
mercaptan residue/azobis(isobutyronitrile) residue in the
proportions 53.27/19.1/19.6/7.14/1.01, prepared, e.g.,
according to the procedure of Example 2 of Brixius
and Simms: - NCO = 9.94%; Mn = 2,700.
Polymer IV. This was Polymer I from which sub-
stantially all MEK had been distilled off.
Polymer V. This was similar to Polymer II except
that the proportions methyl methacrylate/butyl acrylate/
IEM/mercaptan/azo were 24.6/24.2/39.7~10.2/1.3: ~NCO =
7.48 %, Mn ='ca. 12,200.
Polymer VI. This was sim;lar to Polymer I with the
constituents styrene/methyl ~crylate/butyl acrylate/hy-
droxyethyl acrylate~acrylic acid in the proportions 15/
14.8/38/32/0.2: Mw = 3,000 and Mn = 1,500 (see Example
5 of Khanna and Turner).
Comparati~e Example
A. An acrylic enamel solution was prepared as
follows:
~` ~2~3Z3~
Acrylic Polymer I ~281.86 g) was ~ixed thor-
oughly for 20 minutes with a partially methylated/
butylated melamine (Resimine~ X-755; Monsanto; 118.8 g) '~ ,,
in butyl Cellosolve~ t23.2g g~. To this mixture was
added aluminum flake pigment dispersion (60.37 g),
Monastral~ Blue Pigment dispersion (44.4 g; Monastral~
is a trademark'of E. I. du Pont de Nemours and Company),
and a fumed silica dIspersant (66.75 g). The mixture
was stirred for 20 aditional minutes and an acid cata-
lyst, p-toluenesulfonic acid (4'.4 g~, mixed therein over
5 minutes. The final mixture (162 gl was dissolved in MEK
(28'83 g) to form a solution ha~ing a Zahn No. 2 viscosIty
of 35 seconds.
B, Solution from A was air sprayed onto tw~
Bonderite~ 40 steeI panels ~Parker Rust-Pr~of Co.) on (1)
one in two passes to ~uild up a final ('after b~king)
thickness of 1.45 mlls and (2) on the other in three
passes to build a f;nal thickness of 2.37 mils. The
panels were held for 10 minutes at room temperature
(21) and for 10 more at 78 and were cured by kaking at 122.
Both panels exhibited a good appeaxance. When tested
goniophotometrically, distinctness o~ image (DO~) for
both panels was 40 (on a scale ~rom 0 to 100, 100 being
excellent), and 20 gloss was 62.5 and 61.5, respec-
tively. For the second panel,~ L = 25.13 and FOI =
37.36.
EXAMPLE 1
A. Preparation of Dispersant. To a 250-mil,
4-necked flask fitted with thermometer, ice bath, stir-
rer, N2-bubbler, condenser, and addition funnel were
charged 100 g of solution of Polymer II (63~ by weight
of solids in toluene) and 2 g of N-methyl-2-pyrrolidone
additional solvent. This mixture was cooled for a 15-
minute period and to it was added, through the addition
funnel, a 1/1 molar solution in MEX
(15.0 g) of ethanolamine (3.43 g) and Kemamine~ P-997D
i2¢1 l3Z31
(15.4 g). The -CNO/-NH2 molar ratio (in the combined
amines) was also 1/1. After addition was complete (15 -
20 minutes), the ice bath was removed and the reaction
mixture was allowed to rise to room temperature and was
stirred for one hour. Tests showed that all -NCO had re-
acted. Toluene (27.5 g) was added to make up a 60.81
solids solution of the dispersant.
B. Pre~aration of Aluminum Elake Dispersion
.. . . . . . _ _
Aluminum flake (100 g ; Silberline*3141 AR ; 70~
aluminum particles in mineral spirits) was mixed
with MEK (200 ml) for about an hour and filtered to a
cake (Solids = 64.33%). To methyl Cellosolve~ (15 g)
was added 23.32 y o~ the aluminum cake and 0.2 g of
dispersant from A. This mixture was stirred 2-3 hours.
Polymer I (72.79 g) was added and stirring was continued
for 2-1/2 hours. Properties of the resulting aluminum/
acrylic dispersion were: ~olids = 71.46%; Al = 14.3%;
Ratio Dispersant/Al = 0.8/100.
C. Preparation of Paint. Polymer I (80.13 g)
and Resimine~ X-755 (33.75) were agitated together until
thoroughly mixed (20 minutes) and aluminum/acrylic
dispersion ~rom B (14.83 g) and Monastral~ Blue Pigment
dispersion (44.43 g) were added thereto and mixed for
30 minutes. Butyl Cellosolve~ (11.74 g) and
MEK (19 g) were added and mixi~g continued for 15
minutes. Acid catalyst (1.25 g; 20% p-toluenesulfonic
acid) was added and hand-mixed and the mixture reduced
to a Zahn No. 2 viscosity of 35 seconds as before
with MEK (3 g). The physical properties of
30 the paint were substantially the same as those o~ the
Comparative Example.
D. Testing of Paint. As in part B of the Com-
parative Example, paint from C was sprayed on Bonder-
ized~ 40 steel panels. The resultant coatings were held
35 10 minutes at 21, 10 at 78 and 30 at 122. Results
are shown in Table I:
*denotes trade mark
~ 32 3 ~
~ABLE I
Bu~ld
Run (mils~ 20 Gloss DOI
1 1.55 62.5 50
2 2.4S 60.~ 50
3 1.65 60.5 50
4 2~45 61.3 50
1.55 64.5 50
6 2.A5 63.5 50
For Ru~s 1 and 2, ~L = 29.81 and FOI - 43,47.
For Runs 5 and 6, ~L = 3I.01 and I = 45Ø
In comparison with'the Comparative Example,
DOI and FOI are improvea by including the dispersant
of this inventlon.
EXAMPLE 2
A. Pre'~aration of_Dlspers nt. A solution of
Polymer II~ (75 g; 71% by wet'ght of solids in 50~50
ethylene glycol monoethyl ether acetate (Cellosolve~
acetate)/ethyl acetate)and N-methyl-2-pyrrolidone (5 g)
were added to a 250-ml flask equipped as before. The
solution was cooled in an ice bath and to it was added
over 20 minutes a 35/65 molar mixture of ethanolamine
(3.85 g) and Kemamine~ P-997D (32.06 g) in
MEK (25 g), the temperature rising from 8 to 24.
The temperature was raised to 40 and held for one hour.
~he product showed: -NCO = 0~; Solids = 64%; Cellosolve~
acetate - 7.88~; Ethyl acetate = 7.88~; N-methyl-2-
pyrrolidone = 3.62%; MEK = 16.02%.
B. Prepa'ration of'Aluminum Flake Dis~ersion.
A millbase was made u~ from the following:
Ingredi'ent Weight
3Q Washed aluminum flake* 19.93
Dispersant from A 1.16
Toluene 15.66
*Silberline as above. Washed aluminum flake is
aluminum flake plus excess toluene mixed and
filtered.
These three ingredients were mixed for two hours and
~Z08Z31
:L2
mixed further with Polymer I (71.39 g) for 2-3 hours.
The millbase showed: Solids = 72.2%; Al = 14.44%.
C. Prepar ion of Paint. A paint was made up
from the following:
Ingredient Weight
Polymer I 256.40
Resimine~ X-755108.00
Butyl Cellosol~e~ 28.00
Monastral~ Blue'Dispersion 40.36
Mill~ase from B 47.08
Fumed Silica Dispersion 59.76
p-Toluene Sulfonic Acid 4.00
MEK 65.00
The'first three ingredients were mixed for 20
minutes and the last five'added with stirring, continued
for 30 minutes~ The product was diluted with methyl
ethyl ketone: Viscosity a 35 Sec. Zahn No. 2 A
D. Tes'ting of Pa t. When the paint of C was
sprayed on Bonderized~ steeI panels as in Example 1,
results were as follows:
TABLE II
.. ~, . ... .. .. .
Bu~ld (mils~ 2'0' Gl'oss ' DOI
1.1 62.3 55
2~1 64.8 55
Appearance was good.
EX~MPLE 3
Example 2 was substantially repeated except
that the level of dispersant used in the millbase prepa-
ration of Example 2 B, i.e., Dispersant/Al weight ratio
= 5/100, was raised to A. 20~50 and B. 50/50. The 20
gloss with the composition having the 5/100 ratio was
better than with either of the others and was better
with the 20/50 ratio than with the 50/50 ratio.
~Z~ 3Z31
13
EXAMPLE 4
A. Preparation of Dispers~ant. Polymer II
(25 g) dissolved in N-methyl-2-pyrrolidone (,2 g)
and ~!EK ~6 g) was cooled in ice and to it
was added, over a 15-20 minute period, a stoichiometric
mixture (-NCO/-NH2 = 1/1) of ethanolamine (0.92 g; 0.25
mol), Kemamine~ P-997D (I0.'69 g; 0.65 mol) and the
2 (C~2)3-si(c2H5)3 (1-33 g; 0.1 mol This
compound is sold by Union Carblde as A-llO0*) After the
addition of the amines, the reaction mixture was heated
to 40-45 and held at that temperature for an hour.
Upon cooling, the solution showed: Solids = 41.06%.
... .. . .. . .. . . .. . .. ..
B. Pre~aration of Aluminum Flake
Dispersion. Aluminum paste (21.43 g) and dispel-sant
from A (Solution = 1.83 g; Dispersant/Al ratio =
5/100) was mixed in methyl Celiosolve~ (12.0 g) for
2-3 hours. The resultant solution showed: Solids = --
71.42%; Aluminum = 14.28~.
C. P~para'tion of' Paint. Three acrylic
enamels were made up as follows:
Weights (g)
~5~ 1 2 3
Pol~mer I 70.51
Polymer IV --- 64.7~ 64.72
Resimine~ X-755 29.70 29.70 29.70
Butyl Cellosolve~ 5.87 5.87 5.87
Monastral~ Blue Dispersion 10.96 10.96 10.96
Al flake from B 13.09 13.09 ---
Al flake from Ex. 2B ------ 12.g5
Fumed Silica Dispersant18.58 18.58 18.58
p-Toluenesulfonic Acid1.101.10 1.10
Butanol - -15.51 15.51
Isopropanol ---5.79 5.79
MæK 10.0 -~
*denotes trade mark,
~Z~1~23~
14
The first four ingredients named were mixed for
thirty minutes. The next five were added to the mixture
with stirring, continued for thirty minutes, and the last
three added and mixed for five minutes. Paints were
diluted with: (1) 11 g of ~EK (Vis. = 35 Sec.
No. 2 Zahn); (2) 18 g of isopropanol (Vis. = 36);
and (3) 18 g of isopropanol (Vis. = 54.5). In all
cases, P/B (Pigment/Binder) = 4.7/100, Al/Binder =
1.7/100, and Blue Pigment /Binder = 2/100.
D. Testlng_of Paint. Paint was sprayed on
Bonderized~ panels as in Example lD. Results are shown
in Table III:
TABLE III
Build
Paint ~L~ 20 Gloss DOI ~ L FOI
1 1.3573.3 65
1 2~2473~0 65 26.12 46.2
2 1.3171.9 65 --- --
2 2.0372.8 50-65 31.02 50.4
3 1.3170.3 55 --- --
EXAMPLE 5
. ., .... _
A. Pre~aration of Dispersant. A solution
of Polymer V (90 g in 10 g of MEK and 5 g
of N-methyl-2-pyrrolidone) was added to a 250-ml flask
equipped as before. The solution was cooled in ice
with nitrogen bubbled through and to it was added
Kemamine P-997D (28.51 g); n-butylamtne (4.i gJ in the
mole ratio 60~40) and MEK (35 g). After the addition
was complete, the solution was heated to 40-45 and
held there ~or an hour. Upon cooling: Wt. Solids =
50.80%; -NC~ = O.
B. Preparation of Aluminum Flake Dispersion.
. .~
Aluminum flake (25 g), Polymer V (1.47 g) and Polymer VI
(73.06 g) were mixed in methyl Cellosolve~ (35.50 g)
for 2 hours. The resultant solution showed: Solids =
57.13%; Al = 11.43~).
~.208231
C. Pre~aration and Testing of Paint. An
acrylic enamel was made'up as follows:
In~redient We~ght
Polymer VI ;71.i8 g
Resimine~ X-755 300.00 g
~Lue Millbase 164,.6 g
Red Millbase 24.2 g
Green Millbase 25.1 g
Fumed Silica Dispe~sant 168.9 g
The first two ingredients and the next four
were separately mixed and then mixed together. The re-
sultant mixture (87.71 g) was further mixed wlth alumi-
num flake from B and p-toluenesul~onic acid ('0.70 g) in
xylene ~10,02 g~ and higher boiling aromatic hydrocarbon
(19.21 g).
When the pa~nt wa~s spray~d onto a Bond~rized~
steel panel to a thickness of 2.01 mils, the following
properties were found: 20 Gloss = 70.3; DOI = 65; MOI
= 50.67;~ L = 35.17.
Having described my ln~entIon
. .
