Note: Descriptions are shown in the official language in which they were submitted.
55~3
Backgr~und o~ the Invent~on
In recent years, there has been cleveloped a group of
water-dispersible quaternary onium salt-containirlg resins which have
utllity as coating compositions in general and particularly in aqueous
electrodepositable compositions.
These quaternary ammonium group containing resins as a
class, providing highly useful cationic electrodepositable coatings, at
timeS fail to meet the highest commercial standards of film appearance,
detergent resistance and/or corrosion resistance, especially in areas
where the standards set for thesa properties are critical
Description of the Inventio
It has now been found that substantial improvements in
ilm appearance and film properties including detergent resistance and/or
salt spray resistance can be achieved by combining these quaternary
.:
onium (e.g.~ ammonium, sulfonium, phosphonium)group-containing resins
; ~ with either an amine-aldehyde condensate or a methylol-phenol ether,
1:
or a combination of both
:~ ` '
:
:
'
- 2 _
:
~L~6~ 3
The cationic resins which can be utlli~ed in preparing the compo-
sitions of this invention are characterl~ed as ungelled, water-dispersible
resins containing quaternary onium (preferably ammonium) salt groups, and
I preferably containing free epoxy groups. It has been found that the
I presently-preerred resins are based on polyepoxide resins, wherein the
~` resultant resin contains at least one free epoxy group per average molecule
and wherein the resin contains oxyalkylene groups and/or the salt forming the
quaternary onium salt of an acid having a dissociation constant greater
~l than l x lO 5O
I¦ Generally, the quaternary onium salt may be the salt of boric
acid and/or an acid having a dissociation constant greater than boric acid !
including organic and inorganic acids. Upon solubilization, at least a
portion of the salt is preferably a salt of an acid having a dissociation
constant greater than about 1 x 10 5. Preferably the acid is an organlc
carboxylic acid. The presently preferred acid is lactic acid. -
The preferred resins contain at least one epoxy group and preferably
contains about 0.05 percent to about 16 percent by weight nitrogen and at
least about one percent of said nitrogen, preferably about 20 percent, more
I preferably about 50 percent and, most preferably, substantially all of the
nitrogen being in the form of chemlcally-bound quaternary ammonium base salt
~¦ groups; preferably the remainder of said nitrogen being in the form of amino
nitrogen.
The epoxy group-containing organic material can be any monomeric
or polymeric compound or a mixture of compound~ having a 1,2-epoxy group.
It is preferred that the epoxy-con~aining materlal have a 1,2-epoxy equiva-
~ lency greater than 1.0, that is, in which the average number of 1,2-epoxy
I groups per molecule is greater than one. It is preferred that the epoxy
compound be resinous, that is, a polyepoxide, i~e. 9 containing more than one
-- 3 --
.
~655i~
.
epoxy group per molecule. The polyepoxide can be any of the well-known
epo~ides. Examples of these polyepoxides have, for example, been described
in U. S. Patents Nos. 2,467,171; 2,615,007; 2,716,123; 3,030,336; 3,053,855
and 3,075,999. A useful class of pol~epoxides are the polyglycidyl ethers
?a7a~J
of polyphenols, such as Bisphenol ~ These may be produced, for example,
by ~therificatlon of a polyphenol with epichlorohydrin or dichlorohydrin in
the pre~ence of an alkali. The phenolic compound may be bis~4-hydroxy-
phe~yl)2,2-propane, 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)l,l-
ethane, bis(4-hydroxyphenyl)l~l-isobutane; bis(4-hydroxgtertiarybutylphenyl)-
2,2-propane, bis(2-nydroxynaphthyl)methane, 1,5-hydroxynaphthalene, or the
like. Another quite useful class of polyepoxides are produced similarly from
novolak resins or similar polyphenol resins.
Al~o suitable are the similar polyglycldyl ethers of polyhydric
alcohols which ~ay 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, bis~4-hydroxy-
cyclohexyl)2,2-propane, and the like.
There can also be used polyglycidyl esters of polycarboxylic acids
which are produced by the reactio~ of epichlorohydrin or a similar epoxy com-
pound with an aliphatic or aromatic polycarboxylic acid, such as oxalic acid,
succinic acid9 glutaric acid, terephthalic acid, 2,6-naphthylene dicarboxylic
acld, di~erized linolenic acid, and the lika. Examples are diglycidyl
adipate and diglycidyl phthalate.
Also useful are polyepoxides derived frvm the epoxidation of an
olefinically unsaturated alicyclic compound. Included are diepoxides com- -
pri3ing, in part, one or more monoepoxides. These polyepo~ides are non-
phenolic and are obtained by epoxidation of alicyclic olefins, for example,
by o~ygen and selected metal catalystæ, by perbenzoic acid, by acetaldehyde
~noperacetate or by peracetic acid. Among such polyepoxides are the epoxy
~s~z~
alicyclic etherq and esterg which are well known in the art.
Another class of polyepoxides are those containing oxyalkylene
groups in the epoxy molecule. Such oxyalkylene groups are typically group~
of the general formula:
t - (CH - C~
n
where R is hydrogen or alkyl, preferably lower alkyl (e.g., having 1 to 6
carbon atoms) and where, in most instances, m is 1 to 4 and n is 2 to 50.
Such groups can be pendent to the main molecular chain of the polyepoxide
or part of the main chain itself. The proportion of oxyalkylene groups in
I the polyepoxide depends upon many factors, including the chain length of
of the oxyalkylene group, the nature of the epoxy and the degree of water
!~ solubility desired. Usually the epoxy contains at least about one percent
by weight or more, and preferably 5 percent or more of oxyalkylene groups.
¦ Some polyepoxides containing oxyalkylene groups are produced by
reacting some of the epoxy groups of a polyepoxide, such as the epoxy resins
~I men~ioned above, with a monohydric alcohol containing oxyalkylene groups.
Such monohydric alcohols are conveniently produced by oxyalkylating an
alcohol, such as methanol, ethanol, or other alkanol, with an alkylene oxide.
Ethylene oxide, 1,2-propylene oxide and 1,2-butylene oxide are especially
- uReful alkylene oxides. Other monohydrlc alcohols can be, for eaample,
de ~Q~k~)
the commercially available materialR known as Cellosolves and Carbitol~
which are monoalkyl ethers of polyalkylene glycols. The reaction of the
monohydric alcohol and the polyepoxide is generally carried out in the pre-
sence of a catalyst. Formdc acid, dimethylethanolamine, diethylethanolamineS
- 5 -
N,N-dimethylbenzylamdne and, in some cases, stannous chloride are useful
for this purpose.
Similar polyepoxides containing oxyalkylene groups can be pro-
duced by oxyalkylating the epoxy resin by other means, such as by direct
reaction with an alkylene oxide.
The polyepoxide employed to produce the foregolng epoxies con~
tsiniDg u~yalkylene groups contain a sufficient number of epoxy ~roups so that
the average number of residual epoxy groups per molecule remainlng in the
product after the oxyalkylation i~ greater than 1Ø Where oxyalkylene
groups are present, the epoxy resin preferably contains from about 1.0 to
about 9Q percent or re by weight of oxyalkylene groups.
Other epoxy-contalning compounds and r~sins include nitrogeneous
diepoxides such as disclosed in U. S. Patent 3,365,471; epoxy res:Lns from
l,l-methylene bis(5-~ubstituted hydantoin), U. S. Patent 3,391,097; bis-
imide containing diepoxides, U. S. 3,450,711; epoxylated aminomethyld$phe~yl
oxides, U. S. 3,312,664; heterocyclic N,N'-diglycidyl, compounds~ U. S.
3,503,979; amdno epoxy phosphonates, British Patent 1,172,916, 1,3,5-
triglycidyl isocyanurates, as well as other epoxy-containing materials known
in the art.
Another class of resins which may be employed are acrylic polymers
contain$ng epoxy groups. Preferably these acrylic polymers are polyMers
fon~ed by copolymerizi~g an unsaturated epoxy-containing monomer, such as,
for example, glycidyl acrylate or methacrylate.
Any polymerizable monomeric compound containing at least one
CH2YC~ group, preferably in terminal position, may be polymerized with the
unsat~rated glycidyl compounds. Examples of such nomers include:
(1) ~onoolefinic and dioleflnic hydrocarbons, that is, monomers
contai~i~g only atoms of hydrogen and carbon, such as styrene, alpha-methyl
r--~
styrene, alpha-ethyl styrene, isobutylene (2-methyl propene-l), 2-methyl-
butene-l, 2-methyl-pentene-1, 2,3-dimethyl-butene-1, 2,3~dimethyl-pentene-1,
2,4-dimethyl-pente~e-1, 2,3,3-trlmethyl-butene-1, 2 methyl-heptene-l,
2,3-dimethyl-hexene-1, 2,4-dimethyl-hexene-1, 2,5-dimethyl-hexene-1, 2-methyl-
3-ethyl-pentene-1, 2,3,3-trimethyl-pentene-1, 2,3,4-trimethyl-pentene-1,
2-methyl-octene-1, 2,6-timethyl-heptene-1, 2,6--dimethyl-octene-1, 2,3-
dimethyl-decene-l, 2-methyl-nonadecene-1, ethylene, propylene, butylene,
amylene, hexylene, butadiene-1,3, isopropene, and the like;
(2) Ualogenated monoolefinic and diolefinic hydrocarbons, that
is mono=ers containing carbon, hydrogen, and one or more halogen atoms,
such as alpha-chlorostyrene, alpha-bromostyrene, 2,5-dichlorostyrene,
2,5-dibromostyrene, 3,4-dichlorostyrene, ortho-, meta- and para-fluoro-
styrenes, 2,6-dichlorostyrene, 2,6-difluorostyrene, 3-fluoro-4-chlorostyrene,
3-chloro-4-fluorostyrene, 2,4,S-trichlorostyrene, dichloromonofluorostyrenes,
2-chloropropene, 2-chlorobutene, 2-chloropentene, 2-chlorohexene, 2-
chloroheptent, 2-bromobutene, 2-bromoheptene, 2-fluorohexene, 2-fluorobutene,
2-iodopropene, 2-iodopentene, 4-bromohep~ene, 4-chloroheptene, 4-fluoro-
heptene, cis- and trans-1,2-dichloroethylenes, 1,2-dibromoethylene, 1,2-
difluoroethylene, 1,2-diiodoethylene, chloroethylene (vinyl chloride), 1,1-
dichloroethylene (vinylidene chloride), bromoethylene, fluoroethylene,
iodoethylene, l,l-dibromoethyle~e, l,l-fluoroethylene, l,l-diiodoethylene,
1,1,2,2-~etrailuoroethylene, 1-chloro-2,2,2-trifluoroethylene, chlorobuta-
diene and other halogenated diolefinic compounds;
~ 3) Esters of organic and inorganic acids, such as vinyl acetate,
vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valarate, vinyl
caproate, vinyl enanthate, vi~yl benzoate, vinyl toluate, vinyl p-chloro-
benzoate, vinyl-o-chlorobenzoate and siDilar vinyl halobenzoates, vinyl-p-
methoxybenzoate, vinyl-o-methoxybenzoate, vinyl p-ethoxybenzoate, methyl
me~ha ~ylate, ethyl metha~rylate, propyl methacrylate, butyl methacrylate,
~69i6s5%3
amyl methacrylate, hexyl methacrylate, heptyl melthacrylate, octyl meth-
acrylate, decyl methacrylate~ methyl crotonate, and ethyl tiglate;
Methyl acrylate, ethyl acrylate, propy:L acrylate, isopropyl
acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate, hexyl
acrylate, 2-ethylhe~yl acrylate, heptyl acrylate, octyl acrylate, 3,5,5-
trimethylhexyl acrylate, decyl acrylate, and dodecyl acrylatei
I~opropenyl acetate, isopropenyl propionate, isopropenyl butyrate,
isopropenyl isobutyrate, isopropenyl valerate, isopropenyl caproate, i~o-
propenyl enanthate, isopropenyl benzoate, isopropenyl p-chlorobenzoate,
i~opropa~yl o-chlorobenzoate, isopropenyl o-bromobenzoate, isopropenyl m-
chlorobenzoate, isopropenyl toluate, isopropenyl alpha-chloroacetate and
isopropenyl alpha-bromopr~pionate;
Ylnyl alpha-chloroacetate, vinyl alpha-bromoacetate, vinyl alpha-
chloropropionate, vinyl alpha-bromopropionate, vinyl alpha-iodopropionate,
vinyl alpha-chlorobutyrate, vinyl alpha-chlorovalerate and vinyl alpha-
bromovalerate;
Allyl chloride, allyl cyanide, allyl bromide, allyl fluoride,
allyl iodide, allyl chlorocarbonate, allyl nitrate, allyl thiocyanate,
allyl formate, allyl acetate, allyl propionate9 allyl butyra~e, allyl
valerate, allyl caproate, allyl-3,5,5-trimethyl hexoate, allyl benzoate,
allyl acrylate, allyl crotonate, allyl oleate, allyl chloroacetate, allyl
trichloroacetate, allyl chloropropionate, allyl chlorovalerate, allyl
lactate, allyl pyruvate, allyl aminoacetate, allyl acetoacetate, allyl thio-
acetate, as well as methallyl esters corresponding to the above allyl esters,
as well as esterR from such alkenyl alcohols as beta-ethyl allyl alcohol,
beta-propyl allyl alcohols, l-butene-4-ol, 2-methyl-butene-4-ol, 2(2,2-
dimethylpropyl)-l-butene-4-ol, and l-pentene 4-ol;
Me~hyl alpba-chloroacrylate, methyl alpha-bromoacrylate, methyl
alpha-fluoroacrylate, me~hyl alpha-iodoacrylate ethyl alpha, chloroacrylate,
- 8 -
~(~65~
propyl alpha-chloroac~ylate 9 isopropyl alpha-`bromoacrylate, amyl alpha-
chloroacrylate, octyl alpha-chloroacrylate, 3,5,5-trlmethylhexyl alpha-
chloroacrylate, decyl alpha-chloroacrylate, methyl alpha-cyanoacrylate,
ethyl alphA-cyanoacrylate, amyl alpha-cyanoacrylate and decyl alpha-cyano
acrylate;
Dimethyl maleate, diethyl maleate, diallyl maleate, di~ethyl
fumarate, d~ethyl fumarate, dimethallyl fumarate a~d diethyl glutaconate;
(4) Organic nitriles, such as acrylonitrile, methacrylonitrile,
ethacrylonitrile, 3-octenenitrile, crotonitrile, oleonitrile, and the llke.
In carrying out the polymerization reaction, techniques well
kno~n ln the art may be employed. A peroxygen type catalyst is ordinarily
utilized. Diazo compounds or redox catalyst systems can also be employed as
catalysts.
The acrylic polymer may likewise be prepared with monomers of
the type such that the final polymer contains potential crosslinking si~es.
Such monomers include acrylamides or methacrylamides, their N-methylol or
N-methylol ether derivatives; unsaturated monomers containing capped iso-
cyanate groups, or aziridyl groups; and hydroxy-containing unsaturated
monomers, for example, hydroxyalkyl acrylates.
Another method of producing acrylic polymers which may be utilized
ln this l~vention is to react an acrylic polymer containing reactive sites,
such as carboxyl groups or hydroxyl groups, secondary amine groups or other
active hydrogen-contalning sites, with an epoxy-con~aining compound such as
the diglycidyl e~her of Bisphenol A or other polyepoxides as enumerated else-
~hare herein, to provide an epoxy group-containing acrylic polymer.
Vinyl addition polymers which contain alicyclic unsaturation can
be epoxidized to form an epoxy group-containing pol~mer.
~65~i;2~3
Yet another class of polymers which are useul in preparing the
resins of this invention are lsocyanate group-con~aining polyurethanea.
The isocyanate-terminated polyurethane prepolymers employed a~ starti~g
material~ according to the present lnvention may be obtained by the
reaction o~ a selected polymeric glycol. The polyurethane polymer~ include
those which are prepared from polyalkylene ether glycols and dil~ocyanate~.
The term "polyalkylene ether glycol" as used herein refers to a polyalkylene
ether which contains termlnal hydroxy groups. They are sometimes ~nown
as polyoxyalkylene glycol8~ polyalkylene glycol~, or polyalkylene oxide
glycols, or dihydric polyoxyalkylenes. Those useful in preparing the pro- -
ducts of this invention may be represented by the for~ula HO~R0) H, in
which R stands for an alkylene radical and n is an integer. Glycols
containing a ~ixture of radicals, as in the compound HO(CH20C2H40)nH, or
~O(C2H40)~C3H60)m(C2H40)nH, can be used. These glycols are either viscous
liquids or waxy solids. Polytetrame~hylene ether glycols, also know~ as
polybutylene ether glycols, may be e~ployed. Polyethylene ether and poly-
propylene ether glycols, haYing the above-indicated formula, are among the
preferred glycols. ~he prese~tly preferred glycols are polypropylene
glycols with a molecular weight betwaen about 300 and about 1000.
Any of a wide variety of organlc polyi¢ocyanates may be employed
in the reaction, Includi~g aromatic aliphatic, and cycloaliphatic diiso-
cyanates and combinationq of these types.
Instead of the hydrocarbon portion of the polyether glycols used
iD forming the polyurethane products being entirely alkylene, it can contain
arylene or cycloalkylene radicals together with the alkylene radicals as,
for example, in the condensation product of a polyalkylene ether glycol
with alpha, alpha'-dlbrom~-p-xylene in the presence of alkali. In such
product~, the cyclic groupR inserted in the polyester chain are preferably
-- 10 --
~ii5S;~3
phenylene, naphthylene or cyclohexylene radicals or those radicals containlng
alkyl or alkylene substituent~ as in the tolylene, phenylethylene or xylene
radicalq .
Also included in the polyurethane products are those made from a
substantially linear polyester and an organic diisocyanate of the previously
deseribed type. Products of this Rort are descrtbed in ~0 S. Patents Nos.
2,621,}66; 2~625,531 and 2,625~532. The polyesters are prepared by reac~ing
toget~er glycols a~d dicarboxylic acids. Another use~ul group of compounds
for this purpose are the polyester amide resins having terminal hydroxyl
groups. The preferred polyesters may be represented by the formula
H0-B-OOC-B'-COOn-BOH, in which B and B' are hydrocarbon radlcals derived from
the glycol and dicarboxylic acld respectively and n is an integer. In the
preparation of these polyesters, the glycol is used in at least slight excess
80 th~t the polyesters contain terminal hydroxyl groups which are available
for reaction with the isocyanates. The same polyisocyanates and reaction
conditions useful in preparing polyurethanes from the polyalkylene ether
glycols are also useful with the polyesters.
Polyurethane glycols may also be reacted with an organic polyiso-
cyanate-terminated polyurethanes for use as starting materials in the present
invention. The starting polyurethane glycol is prepared by reacting a molar
excess of 8 polymeric glycol with an organic diisocyanate. The resulting
polymer is a polyurethane containing terminal hydroxyl groups which may then
be further reacted wlth additional polyisocyanate to produce the starting
isocyanate-terminated polyurethane prepolymer.
Another starting polyurethane prepolymer may be such as disclosed
in U. S. Paten~ No. 2,861,981, namely; ~hose prepared from a polyisocyanate
and the reaction product of an ester of an organic carboxyllc acid with an
e~cess of a saturated aliphatic glycol having only carbon atoms in its carbon
1~)Ei55~3
chain and a total of 8 to 14 carbon atoms, at least one two-carbon branch
per molecule, and having terminal hydroxy groups separated by at least six
carbon atoms.
I~ is obvious, from the above-described methods by which the poly-
urethane reaction products may be prepared and from the reactants used, that
theqe products will contain a plurality of intralinear radicals of the
formula -NH-CO-O~X-O-CO-NH-, wherein the bivalent radical -O-X-O- is
obtained by re ving the terminal hydrogen atol~ls of the polymeric glycol,
said glycol bei~g selected from the group consisting of polyalkylene ether
glycols, polyurethane glycols, polyalkylene arylene ether glycols, poly-
alkylanecycloalkylene ether ~lycols, polyalkylene ether-polyth-loether
glycols, polyester amide glycols of the formula:
~10-~B-O-CO-B'-CO-O~n-B-OH
where B and B' are hydrocarbon radicals and n is an i~teger, and that a
typical isocyanate-terminatsd polyurethane polymer produced from diisocyan- -
ateR and dihydric glycols will~ on an average, contain ~at a 2:1 NCO:OH
ratio) a plurality of intralinear molecules conforming to the formula:
OCN-Y-NH-CO-O-X-O-CO-NH-Y-NCO
wherein -O-X-O- has the value given previously and Y is the polyisocyanate
hydrocarbon radical.
Polyurethane Prepolymer Preparation
In the preparation of the starting polyurethane polymer, an excess
of the organic polyisocyanate of the polymeric glycol is used, which Tay be
only a slight excess over the stoichiometric amount (i.e., one equivalent
of poly~socyanate for each equivalent of the polymeric glycol). In the
- 12 -
~o65~23
case of a diisocyanate and a dihydric polyalkylene ether,
the ratio of NCO to OH of the polyol will be at lease one
and may be up to a 3:1 equivalent ratio. lhe glycol and
the isocyanate are ordinarily reac-ted by heating with
agitation at a temperature of 50C. to 130 C., preferably
70 C. to 120 C. The ra-tio of organic polyisocyanate com-
pound to polymeric glycol is usually and preferably between
about 1.3:1 and 2.0:1.
The reaction is preferably, but not necessarily,
effected in the absence of a solvent, when the prepo:Lymer
is a fluid~ at processing temperatures. When it is not,
or when it is desired to employ a solvent, convenient
solvents are inert organic solvents having a boiling
range above about 90 C. when the reaction is to be carried
out in open equipment. Lower boiling solvents may, of
course, be used where the reaction is carried out in closed
equipment to prevent boiling off the solvent at the temper-
atures of the reaction. Solvents boiling at substantially
more than 140C. are difficult to remove from a final chain-
extended elastomer at desirable working temperatures, althoughit will be obvious that higher boiling solvents may be
employed where the excess solvent is removed by means other
-~ than by heating or distillation. The solvent, when used,
may be added at the beginning, at an intermediate point,
or at the end of the prepolymer reaction stage, or after
cooling of the formed prepolymer. The solvents to be used
are preferably those in which the reactants have some solubil-
ity but in which the final chain-extended product is insoluble.
Ketones, tertiary alcohols and esters may be used. The
aliphatic hydrocarbon solvents such as the heptanes, octanes
and nonanes, or mixtures of such hydrocarbons obtained from
naturally-occur*ing petroleum sources such as kerosene, or
from synthetically prepared hydrocarbons, may sometimes be
employed. Cycloaliphatic hydrocarbons such as methyl-
cyclohexane and aromatic hydrocarbons such as toluene
~y likewise be used. Toluene and isopropyl acetate are
- 13 -
.
SSZ3
preferred solvents. The amount of solvent used may be varied widely.From 25 to 400 parts of solvent per 100 parts of glycol have been found
to be operable. The excess ~olven~, where large amounts are employed, may
be separated partially or completely from the polymer prior to emulsifi-
cation in the water solution. If an emulsion technique is to be employed
in the chain extension, sometimes the excess solvent is useful and is
allowed to re~ain during the emulsification stage.
The reactants are cooked for a period sufficient to react most,
if not all, of the hydroxy groups, whereafter the prepolymer is allowed to
stand and the free NC0 content determined.
Usual pHs are employed during preparation of the prepolymer, the
reaction preferably being maintained substantially neutral. Bases accel-
erate the reaction, acids retard the reaction, and preferably neither are
added.
These isocyanate group-containing polyure~hanes are then reacted
with an epoxy-containing compound such as glycidolJ for example~ at tempera-
tures of about 25C. to about 45C., usually in the presence of a catalyst
which promotes urethane fonmation.
In the process of the invention, the epoxy group containing com-
~P~.~ no~`~ ~7
pound is reacted with an aE~ salt to form quaternary amine salt group- -
containing resins.
The process of this invention can be used to produce essen~ially
epoxy group-free resins as well as epoxy group-containing resins. Where
the epoxide is reacted with at least about a stoichiometric amount of amine
salt, essentially epoxlde group-free resins are producPd, where resin con-
taining free epoxide groups are desired, the ratio of starting polyepoxide
to amdne salt is selected so as to provide an excess of epoxy groups, thereby
producin~ a resin containing free unreacted epoxide groups. Epoxy-free
- - 14 -
~6SS~3
resin can algo be provided by hydrolysis or post reaction of the epoxide
amine salt reaction product.
Examples of salts which may be employed include salts of ammonia;
primary, secondary and tertiary amlnes, and preferably tertiary amines;
salts of boric acid or an acid having a dissociation constant greater than
that of boric acid and preferably an organic acid having a dissociation
constant greater than about 1 ~ 10 5. The pre~ently preferred acid i8 lactic
acid. Such acids include borlc acid, lactic acid, acetic acid, formic acid,
propionic acid, butyric acid, hydrochloric acid, phosphoric acid and sulfuric
acid. The amines may be unsubstituted amines or amines substituted with non-
reactive constituents such as halogens or hydroxylamines. Specific amines
include dimethylethanolamine, salts of boric, lactic, propionic, Eormic,
butyric, hydrochloric, phosphoric and sulfurlc, or similar salts in tri-
ethylamine, diethylamine, trimethylamine, diethylamine, dipropylamine,
l-amino-2-propanol, and the like. Also included are ammonium borate,
ammonium lactate, ammonium acetate, ammonium chloride, ammonium phosphate,
as well as other amine and ammonium salts as defined above.
A di~ti~ct class of amine compounds within the broader class is
amine containing one or more secondary or tertiary amino groups and at
least one hydroxyl group.
In most cases, the hydroxyl ami~e employed corresponds to the
general formula:
Rl~
~ R3
where Rl and R2 are, preferably, methyl, ethyl or lower alkyl groups, but
can be essentially any other organic radical, so long as they do not inter-
fere with the deslred reaction. Be~zyl, alkoxyalkyl and the like are
s~
examples. Rl can also be hydrogen. The na~ure of the particular groups
i9 less important than the presence of a secondary or tertlary amino
nitrogen atom, and thus higher alkyl, aryl, alkaryl, aralkyl, and substi-
tuted groups of the types can be pre~ent. The group represented by R3 is
a divalent organic group, such a~ al~ylene or substituted alkylene, e.~., -
oxyalkylene or poly(oxyalkylene), or e~en arylene, alkarylene or substituted
arylene. R3 can also be an unsaturated group, e.g., an alkylene group such
R
as -CH~CH- or -C~-C-. Other groups represented by R3 include cyclic or
aromatic groups. One type of useful amine, for instance, is represented
by the formula: -
OH
~ ~ C 2 \
where n is 1 to 3. Dialkanolamines, of the gensral formula RlN(R30~)2,
and trialkanolamines, of the general formula N(R30~)3, are also useful.
Some e~amples of ~pecific amines are as follows: dimethyle~hanol-
amine, dlmethylpropanolamine, dimethylisopropanolamine, dimethylbutanolamine,
diethylethanol~mne, ethylethanolamine, methylethanolamlne, N-ben~ylethanol-
amine, diethanolamine, triethanolamine, dimethylaminomethyl phenol, tris(di-
methylaminomethyl)phenol, 2-12-(dimethylamino)ethoxy]ethanol, l-ll-(dimethyl-
amino)-2-propoxy]-2-propanol, 2-(2-[2-(dimethylamino)ethoxy]ethoxy)ethanol,
1-[2-(dimethylamino)ethoxy]-2-propanol, l-(l-[dimethylamlno) 2-propoxy]-2-
propoxy)-2-propanol, benzyl dime~hyl amine.
Another distinct class of amine compound within the broader class
is any amine containing one or more Recondary or tertiary amino groups and
- 16 -
~ss;~
\
NR3COOH
R2
where Rl and R2 are each preferably methyl, ethyl, or other lower alkyl
~roups, but can be essentially any other or~anic radical, 90 long as they
do not interfere with the desired reaction. Benzyl, alkoxyalkyl, and the
like are examples. Rl can also be hydrogen. The nature of ~heparticular
groups is less lmportant than the presence of a secondary or tertiary
amino nitrogen ato~, and thu3 higher alkyl, aryl, alkaryl, and subs~ituted
groups of these types can be pre~ent. The group represented by R3 is a
divalent organic group, such as alkylene or substltuted alkylene, e.g.,
oxyalkylene or poly(oxyalkylene), or less de~irably, arylene, alkarylene
or substituted arylene. R3 can also be an unsaturated group, e.g., an
alkylene group.
Such amines can be prepared by known methods. For example, an
acid anhydride, such aQ succi~ic anhydride, phthalic anhydride or maleic
anhydride, can be reacted with an alkanolaml~e, such as dimethylethanolamine
or methyldiethanolamine; the group represented by R3 in the ~mines produced
in such cases contain ester groups. Other typ2s of amines are provided,
for example, by reacting an alkylamine with an alkyl acrylate or methacrylates
such as methyl or ethyl acryl~te or methacrylate, as described in U. S.
Patent No. 3,419,525. Preferably9 the ester group is subsequently
hydrolyzed to for~ a free carboxyl group. Other methods for producing amines
of different types can also be employed.
It can be seen that the groups represented by R3 can be of widely
varying types. Some examples are: -Rl-J -R'OCOR'-, and -~-R'O)nCOR' - ,
C~3
where each R' is alkylene, such as -CH2CH2-, -CH2CH-~ e~c., or alkenylene,
- 17 -
"
S23
such as -CH~CH-such as -CH3CM-, and n is 2 to lO or hlgher. Other groups
represented by R' include cyclic or aromatic groups.
Some examples o specific amines are as follows:
N,N-dimethylaminoethyl hydrogen maleate
N,N-diethylaminoethyl hydrogsn maleate
N,N-dimethylaminoethyl hydrogen succlnate
N,N-dimethylaminoethyl hydrogen phthalate
N,N-dimethylaminoethyl hydrogen hexahydrophthalate
2-(2-dimethylaminoethoxy)ethyl hydrogen maleate
l-methyl-2-(2-dimethylaminoethoxy)ethyl hydrogen maleate
2-(2-dimethylaminoethoxy)ethyl hydrogen succinate
1,1-dimethyl-2-(2-dimethylaminoethoxy)ethyl hydrogen succinate
2-12-(2-dimethylaminoethoxy)ethoxy]ethyl hydrogen maleate
beta-(dimethylamino)propionic acid
beta-(dimethylamino)isobutyric acid
beta-(diethylamlno)propionic acid
l-methyl-2-(dimethylamino)ethyl hydrogen maleate
2-(methylamino)ethyl hydrogen succinate
3-(ethylamino)propyl hydrogen maleate
2[2-(dimethylamino)ethoxy]ethyl hydrogen adipate
N,N-dimethylaminoethyl hydrogen azelate
di(N,N-dimethylaminoethyl)hydrogen tricarballylate
N,N-dimethylaminoethyl hydrogen itaconate
l-(l-[l(dimethylamino)-2-propoxy]-2-propoxy)-2-propyl hydrogen maleate
2-~2-(2-[2-(dimethylamino)ethoxy]ethoxy)ethoxy]ethyl hydrogen succinate.
In one embodiment, the epoxy compounds described above may be
reacted with an ester of boric acid or a compound which can be cleaved to
- 18 -
i5~
form boric acid in a medium containing water and preferably an amino-
containing boron ester and/or a tertiary amine salt of boric acid to pro-
duce the epoxy reaction products. The boron compound component utili~ed in
producing the reaction products can be, for example, any triorganoborate
in which at least one of tbe organic groups is substituted with an amino
group. Structurally, such esters are esters of horic acid or a dehydrated
boric acid such as metaboric acid and tetraboric acid, although not
necessarily produced from such acids. In most cases the boron esters
employed correspond to one of the gener~l formulas:
RO-B or RO-B R
~ OR \ o /
where the R groups are the same or different organic groups. The groups
represented by R above can be virtually any organic group, such as hydro-
carbon or 3ubstituted hydrocarbon, usually having ~ot more than 20 carbon
atoms and preferably not more ~han about 8 carbon atoms. The preferred
esters have alkyl groups or polyoxyalkyl groups. At least one of the
organic groups contains an amine gro~p, i.e., a group of the structure:
~Rl
- N \
R2
where Rl and R2 are hydrogen or preferably me~hyl, ethyl or other lower
alkyl groups, but can be essentially any other organic radical, so long as
they do not interfere with the desired reaction. The nature of the particu- -
lar groups is less importact than the presence of an amino ~itrogen atom,
and thus higher alkyl, aryl, alkaryl, aralkyl and substituted groups of
these types can be present. While both Rl and R2 can be hy~rogen (i.e.,
- 19 -
~IOil~55;;2;~
tbe a~ino group is a primary amino group), it is preferred that at lea~t
one be an alkyl or other organlc group, so that the amino group is
secondary or tertiary.
The preferred boron esters correspond to the ~ormula:
X-O-R3-N \R2
where ~ has the structure:
\ R5
\ ~ or R6
R3 and R4 being divalent organic radicals, such as alkylene or substituted
alkylene, e.g., oxyalkylene or poly(oxyalkylene), or less desirably,
arylene3 alkarylene or substituted arylene. R5 and R6 can be alkyl, substi-
tuted alkyl, aryl, alkaryl, or other residue from essentially any monohydroxy
alcohol derived by rem~val of the hydroxyl group. R5 and R6 can be the
same or different.
Examples of boron ¢sters within the above class include:
2-(beta-dimethylaminoi~opropoxy)-4,S-dimethyl-1,3,2~dioxaborolane
2-~beta-diethylaminoethoxy)-4,4,6-trimethyl-1,3,2-dioxaborinane
2-(beta-dimethylaminoethoxy~-4,4,6-trimethyl-1,3,2-dioxaborinane
2-(beta-diisopropylaminoethoxy-1,3,2-dioxaborinane
2-(beta-dibutylaminoethoxy)-4-methyl-1,3,2-dioxaborinane
2-(beta-diethylaminoethoxy)-1 J 3,2-dioxaborinane
2-(gamma-aminopropoxy)-4-methyl-1,3,2-dioxaborinane
2-(beta-methylaminoethoxy)-4,4,6-trimethyl-1,3,2-dioxaborinane
2-(beta-ethylaminoethoxy)-1,3,6-trioxa-2-boracyclooctane
- 20 ~
2-~gamma-dimethylaminopropoxy)-1,3,6,9-tetraoxa-2-boracycloundecane
2-(beta-dime~hylaminoethoxy)-4-4(4-hydroxybutyl)-1,3,2-dioxaborolane
Reaction product of (CH3)2NCH2CH20H + Lactic acid ~ B203 + neopentyl glycol
A number of such boron esters are known. Many are described, for
example, in U. S. Patents Nos. 3,301,804 and 3,257,442. They can be pre-
pared by reacting one mole of boric acid (or equivalent boric oxide) with
at least 3 ~oles of alcohol, at least one mole of the alcohol being an amino-
~ubstituted ~tlcohol. The reaction is ordinarily carried out by refluxlng
the reactants with removsl of the water formed.
The am~no salts and the epoxy compound are reacted by mlxing the
compone~ts, preferably in the presence of a controlled amount of water.
The amount of wster employed should be that amou~t of water which allows for
smooth reaction with retention o epoxy groups but not sufficient to cause
extremely slow or non-reaction. Typically, the water is employed on the
basis of about 1.75 percent to about 20 percent by weight based on the total
reaction mlxture solids and preferably about 2 percent to abou~ 15 percent
I by weight, based on total reaction 601ids.
I Another measure of the amount of water which may be employed is
I the equivalent ratio of water to amine nitrogen present in the reaction
j mixture. Typically the equlvalent ratio of water to amine nitrogen is
i
controlled between about 1.3 and about 16 equivalents of water per
equivalent of amdne nitrogen. Preferably, the ratio of water to amine
` ni~rogen is controlled betweest about 1.5 and about 10.6 equivalents
of water per equivalent of amin2 nitrcgen.
The react$on temperature may be varied between about the lowest
temperature at which the reaction reasonably proceeds~ for example, room
temperature, or in the u~ual case, sl~ghtly above ordinary room temperature
to a ~aximu~ temperature between about 100C. and about 110C.
:.
- 21 -
i
h
l~;S5~
A solvent is not necessary, although one is often used in order
to afford better control of the reaction. Aromatic hydrocarbons or
monoalkyl ethers of ethylene glycol arP suitable solvents. The proportions
of the amine salt and the epoxy compound can be varied and the optimum
proportions depend upon the particular reactants. Ordinarily, however,
from about one part to about 50 parts by weight of the salt per 100 parts
of epoxy compound are employed. The proportions are usually chosen with
reference to the amount of nitrogen, which is typically from about 0.05 to
about 16 percent based on the total welght of the amine salt and the epoxy
compound. Since the amine salt reacts with the epoxide groups of the epoxy
resin employed, in order to provide an epoxy group-containing resin, the
stoichiometric amount of amine employed should be less than the stoichiometric
equivalent of the epoxide groups present, so that the final resin is
provided with one epoxy group 2er average molecule.
;~ Phosphonium group containing resins can be prepared by reacting
the above epoxy compounds with a phosphine in the presence of an acid to
form quaternary phosphonium base group containing resins.
The phosphine employed may be virtually any phosphine which
; does not contain interferring groups. For example, the phosphine may
be aliphatic, aromatic or alicyclic. Examples of such phosphines include
lower trialkyl phosphine, such as trimethyl phosphine, triethyl phosphine,
tripropyl phosphine, tributyl phosphine, mixed lower alkyl phenyl phosphines
such as phenyl dimethyl phosphine, phenyl diethyl phosphine, phenyl
dipropyl phosphine, diphenyl methyl phosphine, diphenyl ethyl phosphine,
diphenyl propyl phosphine, trlphenyl phosphine, alicyclic phosphines such
as tetramethylene methyl phosphine and the like.
The acid e~ployed may be virtually any acid which forms a
~`~ quaternary phosphonium salt. Preferably the acid is an organic carboxylic
- 22 -
SSi~3
acid. Examples of the acids which may be employed are boric acid, lactic
acid, formic acid, acetlc acid, propionic acid, butyric acid, hydrochloric
acid, phosphoric acid, and sulfuric acid. Preferably the acid is an acid
having a dissociation constant greater than about 1 x 10
The ratio of phosphine to acid is not unduly critical. Since
one mole of acid is utilized to form one mole of phosphonium group, it is
pre~erred that at least about one mole of acid be present for each mole of
desired phosphine-to-phosphonium conversion.
The phosphine/acid mixture and the epoxy compound are reacted by
mixing the components, sometimes at moderately elevated temperatures. The
reaction temperature i9 not unduly critical and is chosen depending upon
the reactants and their rates. Frequently the reaction proceeds well at
room temperature or tempe~atures up to 70C., if desired. In some cases,
temperatures as high as about 110C. or higher may be employed. A solvent
is not necessary, although one is often used in order to afford better con-
trol of the reaction. Aromatic hydrocarbons, monoalkyl ethers of ethylene
glycol, and aliphatic alcohols are suitable solvents. The propor-tions of
the phosphine and the epoxy compound can be varied and the optimum proportions
depend upon the particular reactants. Ordinarily, however, from about one
part to about 50 parts by weight of the phosphine per 100 parts of epoxy
compound i5 employed. The proportions are usually chosen with reference
to the a~ount of phosphine, which is typically from about 0.1 to about 35
percent, based on the total weight of the phosphine and the epoxy compound.
Sulfonium group containing resins can be prepared by reacting the
above epoxy compounds with a sulfide in the presence of an acid to form
quaternary sulfonium base group containing resins.
The sulfide employed may be virtually any sulfide which reacts
with epoxy groups and which does not contain interfering groups. For
example~ the sulfide may be aliphatic, mixed aliphatic-aromatic, aralkyl
- 23 -
~ E)65S2~
or cyclic. Examples oE such sulfides include dlalkyl sulfides such as
diethyl sulfide9 dipropyl sulfide, dibutyl sulficle, dihexyl sulfide,
phenyl sulfide or alkyl phenyl sulfides such a~ diphenyl sulfidel ethyl
phenyl sulfide, alicyclic sulfldes such as tetramethylene sulfide, penta-
methylene sulfide, hydroxyl alkyl sulfides such as thiodiethanol, thio- -
dipropanol, thiodibutanol and the like.
The acid employed may be virtually any acid which forms a quater-
nary sulfonium salt. Preferably the acid iQ an organic carboxylic acid.
Examples of acids which may be ~nployed are boric acid, formic acid, lactic
acid, acetic acid, propionic scid, butyric acld, hydro~hloric acid, phos-
phoric acid and sulfuric acid. Preferably the acid is an acid having a
dissociation constant greater than about 1 x 10 5.
The ratio of sulfide to acid i9 not unduly critical. Since one
mole of acid is utilized to form one le of sulfonium group, it is preferred
that at least about one mole of acid be present for each mole of desired
sulfide-to-sulfonium converslon.
The sulfide/acid mixture and the epoxy compound are reacted by
mixing the components, usually at moderately elevated temperatures such as
70-110C. A solvent is not ~ecessary, although one is often used in order
to afford better control of the reaction. Aromatic hydrocarbons, monoalkyl
ethers of ethylene glycol, aliphatic alcohols are suitable solvents. The
proportions of the sulfide to the epoxy compound can be varied and the
optimum proportions depend upon the particular reactants. Ordinarily,
however, from about one part to about SO parts by weight of the sulfide per
100 parts of epoxy compound i~ employed The proportlons are usually chosen
wlth reference to the amount of sulfur, which is typically from about 0.1
to about 25 percent, based on the total weight of the sulfide and the epoxy
compound,
- 24 -
Since the sulfide or phosphine react with the epoxy group, where
epoxy group-containing products are desired, less than an equivalent of
sulfide or phosphine should be employed so that the resultant resin has
one epoxy group per average molecule.
Where it is desired to incorporate boron into the resin molecule,
one method is to incorporate boron by means of an amine borate or nitrogen-
containing ester as described in Canadian Patent 981l848. The boron compound
reacts with available epoxy groups to provide quaternary ammonium borate
groups in the resin molecule.
The reaction of the boron compound may be concluded simultaneously
with sulfonium or phosphonium group formation since the reaction conditions
are similar.
The particular reactants, proportions and reaction conditions
should be chosen in accordance with considerations well-known in the art,
so as to avoid gelation of the product during the reaction. For exc~mplel
excessively severe reaction conditions should not be employed. Similarly,
compounds having reactive substituents should not be utilized along with
epoxy compounds with which those substituents might react adversely at the
desired conditions.
The products forming the resin of the invention may be cross linked
to some extent; however, it remains soluble in certain organic solvents and
can be further cured to a hard, thermoset state. It is significantly char-
acterized by its epoxy content and chemically-bound quaternary onium content.
Aqueous compositions containing the above reaction products are
highly useful as coating compositions and can be applied by an conventional
method, such as by dipping, brushing, etc. They are, however, eminently
suited to application by electrodeposition.
iS~3
Where the resin of the i~vention was prepared employing at least
in part a salt of an acid having a dissociation constant greater than
1 x lO 5, it i9 not necessary to add a solubilizin~ agent to the product to
ohtain a suitable aqueous electrodepositable compo~3ition, although an acid
or acidic solubilizing agent ca~ be added if desired. Where boric acid
sal~s or similar boron compounds, as described above, are employed to pre-
pare the resin without the presence of a salt of an acid having a dissocia-
tion constant greater than l ~ 10 5, compositions within the scope of this
inveneioD can be prepared by adding such an acid, the stronger acid replacing
the boron compound in the resin and the boron compound forming substantially
undissociated boric acid remaining in the aqueous media and being at least
partially codeposited with ~he resin.
The presence of a boron compound in the electrodeposited film is
of substantial benefit in that boron compounds apparently catalyze the cure
of the deposited film, allowing lower cure temperatures and/or harder fil~s.
The acid or acidic solubili7ing agent may be any acid having a
dissociation constant greater than 1 x lO 5. Preferably, the acid or
acidic solubilizing agent should be an organic acid having a dissociation
constant greater than about l x lO 5, the presently preferred acid being
lactic acid. The addition of acid aids ln stab~liæing the resln, since the
epoxy may tend to further polymerize on storage under highly alkaline condi-
tions. In some cases, the acid also helps to obtain more complete dissolution
of the resin. It is also desirable to electrodeposit these coatings from an
acidic or only slightly basic solution (e.g., having a pH between about 3
and about 8.5), and the addition of acid thus is often useful to achieve
the desired pH.
Where a carboxyl amine is employed in forming the resin of the
~nvention, the re~ultant resin con~ains a Zwitterion, or internal salt, that
- 26 -
~1655Z3
is, an interaction between the quaternary group formed and the carboxyl
group present, the carboxyl group dlsplaying a dissociation constant
greater than ~ x lO . Tbe resultant resin i9 inherently self-solubilized
without the use o axternal solubilizing agents.
The resin of the invention, when placed in a water-containing
medium, such as an electrodeposition high solids feed concentrate or the
electrodeposition bath, changes character. Since frequently the boron, if
present, i9 apparently weakly chemically-bound in the resin, it is subject
to cleavage from the resin molecule and, while the boron electrodeposits
with the resin and is found in the electrodeposited film, the boron may
be removed from the water-containing medium, in whole or in part, by
separation means, such as electrodialysis or ultrafiltration, in the form
of boric acid.
Thus, the resin in aqueous medium can be characterized as a water-
containing medium containing an ungelled water-dlspersible epoxy resin
having at least one 1,2-epoxy group per average molecule, and chemically-
bound quaternary onium base salts.
The preferred ammonium resin con~ains from about 0.05 to about
16 percent by weight of nitrogen, at least about one percent of said nitrogen
and preferably about 20 percent, more preferably about 50 percent, and most
preferably substantially all of the nitrogen being in the form of chemically-
bound quaternary ammonium base salt groups; preferably the remainder of
said nitrogen being in the form of amino nitrogen, preferably tertiary amine
nitrogen, said water-containing medium containing in the preferred embodiment
from about 0.01 to about 8 percent by weight of boron metal contained in
boric acid and/or a borate or boric acid complex.
The amine-aldehyde products employed herein are aldehyde conden-
sation products of melamine, urea, benzoguanamine, or a similar compound.
- 27 -
;~5523
They may be water-soluble or they may be organic solvent-soluble. Generally,
the aldehyde employed is formaldehyde, although useful products can be
made from other aldehydes, such as acetaldehyde, crotonaldehyde, acrolein,
benzaldehyde, furfural, and others. Condensation products of melamine,
ur~a and benzoguanamine are the mo~t common and are preferxed, but products
of other amines and amides in which at least one amino gxoup i8 present can
also be employed.
For example, such condensation products can be produced from
tria~ines, dia7ines, triazoles, guanadines, guanamines, and alkyl and aryl-
substituted and cyclic ureas, and alkyl and aryl-substituted melamines.
Some examples of such compounds are N,N'-dimethyl urea, benzyl urea, N,N'-
e~hylene urea, diazine diamide, formaguansmine, acetoguanamine, ammeline,
2-chloro-4,6-diamine-1,3,5-triazine, 3,5-diaminotriazole, 4,6-diamino-
pyrimidine, 2,4,6-triphenyltriamine-1,3,5 triazine, and the like.
These aldehyde condensation products contain methylol groups or
similar alkylol groups, depending upon the particular aldehyde employed.
Ordinarily, in producing amine-aldehyde condensation products, all or part
of these methylol groups are etherified by reaction with an alcohol to pro--
duce an alkylated product. In the present invention,there are employed
those condensation products which are substantially completely alkylated.
By this it is meant that all or substantially all of the methylol groups
have been etherified. Generally speaking, those products containing not
more than a~ average of about one unalkylated alkylol group per molecule are
utilized.
Various alcohols can be em~loyed for the etherification of the
alkylol groups. These include essentially any monomeric alcohol, with the
preferred alcohols being methanol, ethanol, propanol, butanol, and other
lower alkanols having up to about 5 carbon atoms, including isomers such as
- 28 -
1~655Z3
2-methyl-1-propanol. There can also be employed alcohols such as the lower
alkyl monoethers of ethylene glycol and the like; for instance, ethyl
Cellosolve and butyl Cellosolve. Higher alcohols can be used but are less
desirable because they tend to affect the film properties of the baked
film. When the alkylated amine-aldehyde condensate is to be utilized in
a vehicle to be e~ployed in a water-dispersed coating composition, it is
preferred to employ a water-soluble alcohol in the etherification.
The amine-aldehyde condensation products are produced in a manner
well-known in the art, using acidic or basic catalysts and varying conditions
of time and temperature~ The aldehyde is often employed as a solution in
water or alcohol, and the condensation, polymerization and etherification
reactlons may be carried out either oequentially or slmultaneously.
The methylol phenol ethers employed herein are compositions con-
sisting essentially of one or more methylol phenol ethers of the formula;
OR
~ (C~201l)D
where n i8 an integer from 1 to 3 and R is an unsaturated aliphatic group
or a halog~n-substituted unsaturated aliphatic gxoup. The groups repre-
sented by R should contain at least 3 carbon atoms and can be, for example,
allyl groups (which are preferred~ or others such as methallyl, crotyl,
bute~yl, or the like. The halogen-substituted unsaturated groups represented
by R can be various mono- and poly-halogenated derivatives of the above
unsaturated aliphatic groups, for example, 2-chloroallyl9 3-chloroallyl, 3-
chloro-2-methallyl, l-chloro-2-butenyl, and corresponding groups containing
other halogens such as bromine and fluorine.
- 29 -
10655Z3
The methylolphenol ether compositions employed herein are des-
cribed in U. S. Patent No. 2,579,330, and as disclosed therein can be
produced from sodium or barium salts or 2,4,6-tris(hydroxymethyl~phenols
which are obtained by reacting formaldehyde with phenol in the presence
of, sodium or barium hydroxide. Several methylol phenol ether compositions
of this type are commercially available and tbese generally comprise mixtures
of allyl ethers of mono-, di- and trimethylol phenols (substituted in the
ortho, para, and meta positions~. The trimethylolated derivative is
gene~ally the predominant component of the composition. Such commercially
available methylol phenol ether compositions are preferred for use in the
invention.
The proportion of amine-aldehyde products and/or phenol ether
and quaternary-containing resin in the coating composition can be varled
considerably. The optimum amount employed depends upon the particular
properties desired in the product and also depends in part on the particular
quateFnary onium group-contai~lng resin. In the preferred products, the
amine-aldehyde products or the phenol ethers comprise from about 2 to about
,. .
30 percent by weight, based on the weight of the combination with quaternary
onium group-containing re~ins, although as little as one percent give some
degree of improvement in properties of the composition and as much as about
50 percent can be utilized in some cases. Where both amine-aldehyde product
and phenol ether are utilized, generally a combined weight of between about
one percent and about 50 percent by weight may be employed, preferably
between about two percent and about 30 percent. The ratio of amine-aldehyde
product and phenol ether is generally about 100:1 to 1:100, and preferably
between about 5:1 and 1:5.
The concentration of the product in water depends upon the process
parameters to be used and is, ln general, not critical, but ordlnarily the
- 30 -
~6SSZ3
ma~or proportion of the a~ueous co~p~sition is w~ter, e.g., the composition
may contain from one to 25 percent by weight of the resin. PreEerably,
the electrodepositable compositions o~ the invention contain a coupling
solvent. The use of a coupling solvent provldes for improved deposited
film appearance. These solvents lnclude hydrocarbons, alcohols, esters,
ethers, and ketones. The preferred coupling solvents include mono-
alcohols, glycols and polyols as well as ketones and ether alcohols.
Specific coupling solvents include isopropanol, butanol, isophorone,
Pentoxone (trademark for 4-methoxy-4-methyl pentanone-2), ethylene and
propylene glycol, the ~onomethyl, monoethyl and monobutyl ethers of
ethylene glycol, 2-ethylhexanol, and hexyl Cellosolve. The presently
preferred coupling solvent is 2-ethylhexanol. The amount of solvent is
not unduly critical, generally between about 0.1 percent and about 40
percent by weight of the dispersant may be employed, preferably between
about 0.5 and about 25 percent by weight of the dispersant is employed.
In most instances, a pigment composition and, if desired,
various additives such as anti-oxidants, surfactants, or wetting agents,
for example, Foam Kill 639 ~trademark for a hydrocarbon oil~containing
inert diatomaceous earth), as well as glycolated acetylenes {such as
~20 those sold under the trademark Surfynol, for example), sulfonates,
sulfated fatty amides, and alkylphenoxypolyoxyalkylene alkanols, and
the like are included. The pigment co~position may be of any conventional
type, comprising, for example, iron oxides, lead oxides, strontium
chromate, carbon black, titanium dioxide, talc, barium sulfate, as well
as color pigments such as cadmium yellow, cadmium red, chromic yellow,
and the like~
In the electrodeposition processes employing the aqueous
coating compositions described above, the aqueous composition is placed in
contact with an electrically~conductive anode and an electrically-conductive
cathode,
`` 1~655Z3
with the surface to be coated being the cathode, while in contact with the
bath contsining the coating composition, an adhereslt film of the coating
composition i~ deposited on the cathode. Thi~ i8 direc~ly contrary to the
processes utilizing polycarboxylic acid resins, as in the prior art, and
the advantages tescribed are, in large part, attributed to this cathodic
deposition.
The co~ditions under which the electrodeposition is carried out
are, in general similar to those used in elec~rodeposition of oeher types
of coatings. The applied Yoltage may be varied greatly and can be, for
example1 as low as one volt or as high as several thousand volts, although
typically between 50 and 500 volts. The current density is usually between
about 1.0 ampere and 15 amperes per square foot, and tends to decrease during
electrodeposition.
The method of the inveneion is applicable to the coa~ing of any
conductive substrate, and especially metals such as steel, aluminum,-copper,
magnesium and the like. After deposition, the coating is cured, usually by
baking at elevated temperatures. Temperatures of 250F. to 500F. for one
to 30 minutes are typical baking schedules utili~ed.
During the cure, especially at elevated temperatures, at least a
sub3tantial portion of the quaternary am~onium base decompo~es to tertiary
amine nitrogen, which aids in the crosslinking of the coating, which upon
curing i8 infusible and insoluble. The presence of boron salts and com-
plPxes ln the film increases the rate of crossli~king, reduces the tempera-
ture3 necessary for acceptabl2 curing in com~ercially-reasonable times and
produces coatings with improved hardness and corroslon resistance.
Illustrating the invention are the following examplesp which,
however, are not to be construed as limiting the invention to their details.
All parts and percentages in the examples, as well as throughout the
specification are by weight unless otherwi~e specified.
- 32 -
.
i23
EXAMPLE A
Into a reactor equipped with thermometer, stirrer, distillation
apparatus witb reflux and water trap, and means for providing an inert
gas blanket were charged 741.6 part~ of dimethylethanolamine, 714 parts
lactic acid and 300 parts toluene. The reaction mixture was heated to
between 105C. and 110C. for 4 hours. A total of 120 parts of water were
collected with an index of refractlon of nD 1.377. There was then added
245 par~s of boric oxide, and 728 parts neopentyl glycol. The reaction
mixture was heated between 115C. and 128C. for approximately 4 hours,
collecting an additional 205 parts of water of reaction n25 1.386. The
reaction product had a percent nitrogen content of 4.51 and has a proposed
structure of:
'
3 \ / 0-~~~C ~
- CH2 - C~2 - 0 - C - CH - 0 -- B ~ C (CH3)2
This product is hereinafter referred to as the product of Éxample A.
`:
'
EXAMPLE I
A quaternary ammonium salt group-containing resin was prepared as
fo~lows:
Into areactor equipped ~ith thermometer, stirrer, reflux conden-
;~ ser a~d means for provlding an ~nert gas (nitrogen) blanket were charged
~ t't~a d~
;~~ ~l 1700 parts of Epon 829~and 3Q2 parts of Bisphenol A. The reaction mixture
was heated with stirring to 180C. under nitrogen, and an exotherm was noted.
The reaction mixture was held at 180C. ~o 190C. for 45 minutes, then cooled
~;~ to 100C. There was then added 790 parts of a polypropylene glycol (molecular
weight approximately 625) and the mixture heated to 130C., at which time
,~
:
- 33 -
,
1CD655;23
five parts of dimethyl ethanolamlne was added. The reaction mixture was
held at 130C. to 140C. for about 7 hours until the reaction mixture had
a Gardner-Holdt viscosity of L~, measured at 50 percent solids in a 90/10
isophorone/toluene mixture.
The resultant product had the following analytical values
(ad~usted to 100 percent solids): epoxy equivalent 797, hydroxyl value
282.
To the above reaction product was then added a solution of 15.2
parts of Foam Kill 639 in 200 parts of 2-ethylhexanol at 119C. There was
then added 3.5 parts of 90 percent formic acid (to neutralize the amine
catalyst) and then added 135 parts of isopropanol, cooling the reaction
mixture to lOOnC.
At 87C. there was added a solution of 318 part~ of the amine
salt of Example A, 80 parts of isopropanol and 200 parts of deionized
water. The reaction mixture was then heated at 91C. to 94C. for 75
minutes and there was then added ~ mixture of 520 F~arts of deionized water
and 135 parts of isopropanol. The final reaction product contained 65.7
percent solids and had a Brookfield viscosity of 55,000 centipoises at
25C-
The final reaction product had the following analytical values(adjusted to 100 percent solids): epoxy equivalent 1335; hydroxyl value 202.
EXAMPLE II
A pigment paste was prepared by mixing the following and grinding
to a Hegmann No. 7 in a suitable pigment dispersing apparatus:
Parts by Weight
Resin of Example I 180.0
Titani~un dioxide 5b,4.0
Aluminum silicate 62.4
Red iron oxide 1.32
Yellow iron oxide 13.55
Carbon black 2.25
Deionized water 257.0
- 34 --
iZ3
EXAMPL~ III
The following materials were stirred mechanically in a
vessel until a uniform consistency was obtained: the resin of Example I,
the pigment paste of Examp:Le II and, where employed, either an amine-
aldehyde condensation product or a methylol phenol ether or the combina-
tion of the two. The deionized water was added while stirring, producing
an aqueous paint bath of approximately 10 percent non-volatile solids.
Steel panels were electrodeposited as described below.
The panels tested in salt spray we~e zinc phosphated
treated steel panels (sold under the trademark Bonderite 37) electro-
coated at a bath temperature of 80T. for 90 seconds. Voltage was varied
to achieve film build. The films were baked at 400F. for 20 minutes
and scribed in the form of an X to bare metal. The panels when removed
were scraped and tape tested for film lifting.
.
- 35 -
1~5~Z3
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36
3L~)65~3
In addition, the same compositions were coated on calcium-
zinc phosphAte ~reated steel panels (sold under the trademark Metabond-
36) and baked at 450F. for 20 minutesg with film thicknesses of 0.8-
1.0 mils and tested or detergent resistance.
One percent Tide (trademark~ detergent dissolved in
deioni~ed water was stirred mechanically at 72C.-74C. (160F.-165F.).
The electrocoated panels were hung in the detergent solution. The
panels were inspected daily and removed when blister failure occurred.
~ 11 modified films displayed improved detergent resistance~
~he films containing phenol ethers were especially improved.
According to the provislons of the Patent Statutes,
there are described above the invention and what are now considered to
be its best embodiments; however, within the scope of the appended
claims, it is to be understood that the invention can be practiced
otherwise than as specifically described.
,
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